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              AIR POLLUTION ASPECTS

                       OF

                HYDROCHLORIC ACID
                Prepared for the
  National Air Pollution Control Administration
Consumer Protection & Environmental Health Service
   Department of Health, Education, and Welfare
           (Contract No. PH-22-68-25)
        Compiled by Quade R. Stahl, Ph.D,
              Litton Systems, Inc.
         Environmental Systems Division
               7300 Pearl Street
            Bethesda, Maryland 20014

                 September 1969

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                          FOREWORD


       As the concern for air quality grows, so does the con-

cern over the less ubiquitous but potentially harmful contami-

nants that are in our atmosphere.  Thirty such pollutants have

been identified, and available information has been summarized

in a series of reports describing their sources, distribution,

effects, and control technology for their abatement.

       A total of 27 reports have been prepared covering the

30 pollutants.  These reports were developed under contract

for the National Air Pollution Control Administration  (NAPCA) by

Litton Systems, Inc.  The complete listing is as follows:


    Aeroallergens (pollens)       Ethylene
    Aldehydes (includes acrolein  Hydrochloric Acid
      and formaldehyde)           Hydrogen Sulfide
    Ammonia                       Iron and Its Compounds
    Arsenic and Its Compounds     Manganese and Its Compounds
    Asbestos                      Mercury and Its Compounds
    Barium and Its Compounds      Nickel and Its Compounds
    Beryllium and Its Compounds   Odorous Compounds
    Biological Aerosols           Organic Carcinogens
      (microorganisms)            Pesticides
    Boron and Its Compounds       Phosphorus and Its Compounds
    Cadmium and Its Compounds     Radioactive Substances
    Chlorine Gas                  Selenium and Its Compounds
    Chromium and Its Compounds    Vanadium and Its Compounds
      (includes chromic acid)     Zinc and Its Compounds


       These reports represent current state-of-the-art

literature reviews supplemented by discussions with selected

knowledgeable individuals both within and outside the Federal

Government.  They do not however presume to be a synthesis of

available information but rather a summary without an attempt

to interpret or reconcile conflicting data.  The reports are

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necessarily limited in their discussion of health effects for

some pollutants to descriptions of occupational health expo-

sures and animal laboratory studies since only a few epidemic-

logic studies were available.

       Initially these reports were generally intended as

internal documents within NAPCA to provide a basis for sound

decision-making on program guidance for future research

activities and to allow ranking of future activities relating

to the development of criteria and control technology docu-

ments.  However, it is apparent that these reports may also

be of significant value to many others in air pollution control,

such as State or local air pollution control officials, as a

library of information on which to base informed decisions on

pollutants to be controlled in their geographic areas.  Addi-

tionally, these reports may stimulate scientific investigators

to pursue research in needed areas.  They also provide for the

interested citizen readily available information about a given

pollutant.  Therefore, they are being given wide distribution

with the assumption that they will be used with full knowledge

of their value and limitations.

       This series of reports was compiled and prepared by the

Litton personnel listed below:

       Ralph J. Sullivan
       Quade R. Stahl, Ph.D.
       Norman L. Durocher
       Yanis C. Athanassiadis
       Sydney Miner
       Harold Finkelstein, Ph.D.
       Douglas A.  Olsen, Ph0D.
       James L. Haynes

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       The NAPCA project officer for the contract was Ronald C.




Campbell, assisted by Dr. Emanuel Landau and Gerald Chapman.




       Appreciation is expressed to the many individuals both




outside and within NAPCA who provided information and reviewed




draft copies of these reports.  Appreciation is also expressed




to the NAPCA Office of Technical Information and Publications




for their support in providing a significant portion of the




technical literature.

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                         ABSTRACT







       Hydrochloric acid irritates the membranes of the eye




and upper respiratory tract, and prolonged exposure to low




concentrations can cause erosion of the teeth.  Severe expo-




sures can result in pulmonary edema and laryngeal spasm, both




of which can be fatal.  There are no known chronic or acute




systemic effects of hydrochloric acid.  Hydrochloric acid is




also a phytotoxicant, and its emissions have been responsible




for plant damage in several instances.  Recent data indicate




that it is a stronger phytotoxicant than reported in the




earlier literature.




       The acid is strongly corrosive to most metals.  Hydro-




gen chloride gas emissions are read.ily converted to hydrochlo-




ric acid by the moisture in the air.  Hydrogen chloride is a




by-product of many organic chlorinating reactions; in some




instances the hydrogen chloride is collected for use, but in




small operations it may not be economically feasible to recover




the gas.  Hydrogen chloride emissions result from the burning




of coal, chlorinated plastics,  and paper.  No information has




been found on the concentration of hydrochloric acid in the




atmosphere.   The major uses of hydrogen chloride or hydrochlo-




ric acid are in manufacturing chemicals, producing metals, and




acidizing oil wells.  Effective control of emissions can be

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accomplished by the use of water scrubbing equipment.



       No information has been found on costs for obtaining



and maintaining the control equipment and economic losses due



to hydrochloric acid emissions.  Methods of analysis for hydro-



chloric acid are based on determining the acidity or the chlo-



ride content of samples, and therefore, other strong acids or



chloride salts may cause interference.

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                         CONTENTS
FOREWORD
ABSTRACT

1.  INTRODUCTION 	  1

2.  EFFECTS	3

       2.1  Effects on Humans	3
            2.1.1  Toxic ity	3
            2.1.2  Sensory Thresholds  	  5
            2.1.3  Synergistic Effects 	  5
       2.2  Effects on Animals	5
            2.2.1  Commercial and Domestic Animals ....  6
            2.2.2  Animal Experiments  	  6
       2.3  Effects on Plants	7
            2.3.1  Phytotoxicity 	  7
            2.3.2  Incidents of Plant Damage 	 10
       2.4  Effects on Materials	11
       2.5  Environmental Air Standards  	 12

3.  SOURCES	14

       3.1  Natural Occurrence 	 15
       3.2  Production Sources 	 15
            3.2.1  By-Product Process  	 16
            3.2.2  Salt-Acid Process 	 18
            3.2.3  Chlorine-Hydrogen Synthesis 	 20
       3.3  Product Sources	21
            3.3.1  Manufacture of Chemicals	21
            3.3.2  Metal Production  	 22
            3.3.3  Other Uses	23
       3.4  Other Sources	  . 23
            3.4.1  Coal	24
            3.4.2  Fuel Oil	26
            3.4.3  Automobile Exhaust	26
            3.4.4  Burning of Chloride-Containing
                     Plastics	27
            3.4.5  Burning of Paper Products 	 28
            3.4.6  DDT Production	29
            3.4.7  Lemon Pulp Extraction	29
       3.5  Environmental Air Concentrations 	 30

4.  ABATEMENT	31

5.  ECONOMICS	34

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                   CONTENTS (Continued)
6.  METHODS OF ANALYSIS	35

       6.1  Sampling Methods 	  35
       6.2  Qualitative Methods  	  35
       6.3  Quantitative Methods 	  36

7.  SUMMARY AND CONCLUSIONS	39

REFERENCES	43

APPENDIX	52

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                       LIST OF TABLES
 1.  "Ethyl" Antiknock Compound-Tel Motor 33  Mix  ....   27

 2.  Properties of Hydrogen Chloride and Hydrochloric
     Acid	52

 3.  Summary of Reported Effects of Inhalation of Hydrogen
     Chloride by Humans	54

 4.  Summary of Reported Effects of Inhalation of Hydrogen
     Chloride in Animals	56

 5.  Summary of Reported Toxic Effects of Hydrogen
     Chloride Exposure on Plants  	   60

 6.  Emissions of Hydrochloric Acid in Selected Areas of
     Niagara County, New York	64

 7.  Hydrochloric Acid Production in the United States/
     1958-1967	65

 8.  Production of Hydrochloric Acid by Process and
     State	66

 9.  Major Producers of Hydrochloric Acid (Muriatic Acid)
     in the United States	67

10.  Consumption of Hydrochloric Acid by Uses,  1963 ...   69

11.  Consumption of Hydrochloric Acid by Selected
     Industries, 1963 and 1958	70

12.  Chlorine Content of Selected United States Coals .  .   71

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1.   INTRODUCTION




           Hydrogen chloride (HC1) is a hygroscopic, colorless gas




    with a strong, pungent, and irritating odor.  Because of its




    high solubility in water, the gas fumes in moist air.  An aque-




    ous solution of hydrogen chloride is called hydrochloric acid.




    Emissions of hydrogen chloride are readily converted to hydro-




    chloric acid fumes and droplets in air or when inhaled into




    the lungs.  The strong dehydrating properties of hydrogen chlo-




    ride can result in serious burns of the skin or mucous mem-




    branes.  Hydrochloric acid is extremely corrosive to most




    materials.  (See Table 2 in the Appendix for the properties




    of hydrogen chloride and hydrochloric acid.)




           Inhalation of hydrochloric acid causes coughing and




    choking, as well as inflammation and ulceration of the upper




    respiratory tract.  Irritation of the eye membranes is another




    effect, and exposure to high concentrations can cause clouding




    of the cornea.  The teeth can also be affected, and erosion




    may result.  Hydrogen chloride and hydrochloric acid are also




    phytotoxicants that damage the leaves of a great variety of




    plants.  Several episodes of plant damage from hydrochloric




    acid emissions have been reported.




           The possible sources of emissions of hydrogen chloride




    or hydrochloric acid are not only their commercial production

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and use, but also the burning of paper products and fossil




fuels.  Many industries also produce hydrochloric acid as an




unwanted by-product in the manufacture of chemicals.  The




emissions can be effectively controlled with the available




methods, which usually involve the use of water scrubbing




equipment.

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2.   EFFECTS

    2.1  Effects on Humans

           Little information is available on the toxicity of

    hydrogen chloride or hydrochloric acid when inhaled by humans.

    Most of the information cited in the literature was obtained

    from studies conducted 30 to 80 years ago pertaining to occu-

    pational exposure.

    2.1.1  Toxicity

           Hydrochloric acid primarily irritates and attacks the

    membranes of the eyes and upper respiratory tract. 34,73  i>ne

    effects increase in severity from irritation to pulmonary

    edema, and even to death in extreme cases, depending upon the

    concentration and duration of exposure.  No organic damage

    results from exposure to 7,000 |-ig/m3 (5 ppm*).113  Irritation

    of mucous membranes occurs at 15,000 ug/m3 (10 ppm),113 although

    workers accustomed to hydrochloric acid exposure can work undis-

    turbed, at this concentration.45'72  Work becomes difficult, but

    not impossible, in the concentration range of 15,000 to 75,000

    ug/m3  (10 to 50 ppm),  '   and irritation of the throat mem-

    branes has been reported at exposures of 50,000 (j.g/m3  (35 ppm).87

    Work becomes impossible at levels above 75,000 (jg/m3 ,72 and

    exposure to levels of 75,000 to 150,000 [ig/m3  (50  to 100 ppm)

    cannot be tolerated, by humans for longer than 60 minutes. 44,45,52
           *Conversion factor used  in this  report:   1  ppm  is  approxi-
    mately equal to 1,470 ug/m3.

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Exposure for only a  few  minutes  at  1,300  to  2,000 ppm may be




lethal;52/87 the acid neutralizes the  alkali of  the tissues




and causes inflammation  of the upper respiratory tract,  pul-




monary edema, or laryngeal spasm, with death possibly resulting.




       Mists of hyd.rochloric  acid, are  not as dangerous to humans




as hydrogen chloride gas because the acid has no strong dehy-




d.rating effect on the tissues.^7 However, acid  mists from




heated metal-pickling solutions  may cause bleeding of the nose




and gums, ulceration of  the nasal and  oral mucosae,  and  tender-




ness of the facial skin  so that  shaving becomes  painful.45  A




study conducted by Toyama et  al..112 of  an electrical  appliance




factory indicated that people not accustomed to  hydrochloric




acid mists showed a  9 percent decrease in the pulmonary venti-




latory peak flow rate when exposed  for  1  hour to hydrochloric




acid mists (6 |_i in d.iameter), whereas  the workers exhibited no




change.




       Prolonged, exposure to  low concentrations  of hydrochloric




acid causes erosion  of the teeth. ->  However,  there are no known




systemic effects, either acute or chronic, from  inhalation of




hyd.rochloric acid or hydrogen chloride.-  ' °'




       The effects of hydrogen chloride on humans are summarized




in Table 3  in the Appendix.

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2.1.2  Sensory Thresholds

       The odor perception threshold values for hydrochloric

acid given in the literature include 100 to 200 |-ig/m3 (0.067 to

0.134 ppm), 28'29 1,500 to 7,500 iag/m3 (1 to 5 ppm),45 and 14,700

Hg/m3 (10 ppm).105

       Elfimova28'29 has studied the threshold reflex of the

eyes, respiratory action, and vascular reaction upon exposure

to hydrochloric acid aerosols.  The results are summarized in

Table 3 in the Appendix.

2.1.3  Synergistic Effects

       Stayzhkin85'102 investigated the effect of chlorine and

hydrogen chloride gas mixtures on man.  In his study of the odor

threshold, the effect on reflex reactions of eye sensitivity

to light and of optical chronaxy were examined.  His results

indicated that the two gases acted in combination in an

additive manner to produce a perceivable odor when neither gas

could be detected alone.  The effect is expressed by the following

relationship where X must equal one or greater to have a

perceivable odor:

    x  _  Concentration Clp   +   Concentration HC1
          Odor threshold C12      Odor threshold HC1

Furthermore,  the physiological and neurological effects of the

mixtures were also in the nature of arithmetical summation.

2.2  Effects on Animals

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2.2.1  Commercial and Domestic Animals




       No reports were found in the literature describing




injury to domestic, commercial, or wild animals from exposures




to hydrogen chloride or hydrochloric acid in rural or urban




environments or near factories that produce or use the acid.




2.2.2  Animal Experiments



       Mackle et_ _a_l_.69 exposed one monkey, three rabbits, and




three guinea pigs to 50,000 ug/m3 (33 ppm) of hydrogen chloride




for a period of 4 weeks (6 hours per day, 5 days per week).




None of these animals exhibited immediate toxic effects or




pathological changes.  However, the authors commented that




inhalation of hydrogen chloride daily for one month at 50,000




l_ig/m3 (33 ppm) may be dangerous.  Rabbits and guinea pigs were




not killed at a concentration of 100,000 ug/m3 (67 ppm) for 5




days (6 hours per day).  However, it was noted that the guinea




pigs were more sensitive to irritant properties of hydrogen




chloride than the rabbits, but the rabbits exhibited more pul-




monary and nasal damage than the guinea pigs.  At higher con-



centrations, repeated exposures resulted in a weight loss that




was proportional to the degree of exposure.  A concentration of




1,000,000 ug/1™3 (670 ppm) of hydrogen chloride for 2 to 6 hours




was lethal to rabbits and guinea pigs.  Furthermore, 30 minutes'




exposure at approximately 6,400,000 ug/m3  (4,300 ppm) was lethal




to all the animals.  At these concentrations, hydrogen chloride




causes necrosis of the tracheal and bronchial epithelia and also




pulmonary edema, atelectasis, emphysema, and pulmonary blood

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vessel damage.  '     Production of lesions in the liver and




other organs by hydrogen chloride is also described. "




       After Lehmann°4 exposed cats, rabbits, and guinea pigs




to 150,000 to 210,000 ug/m3 (100 to 140 ppm) of hydrogen chlo-




ride for 6 hours, he found slight corrosion of the cornea and




upper respiratory irritation in the animals.  Clouding of the




cornea occurred after exposure to a concentration of 2,000,000




|_ig/m3 (1,350 ppm) for approximately 90 minutes.  After approxi-



mately the same exposure time to a concentration of 5,000,000




M.g/m3 (3,400 ppm), death occurred in 2 to 6 days.




       Leitz -* found that when the respiratory rate is increased




by an elevation in environmental temperature, the amount of




hydrogen chloride absorption is also increased, thereby height-



ening the danger of exposure to low concentrations.



       Table 4 in the Appendix summarizes the reported effects




of hydrogen chloride inhalation by animals.




2.3  Effects on Plants




2.3.1  Phytotoxicity




       Haselhoff and Lindau   studied the effects of hydrogen




chloride and hydrochloric acid on plants after an incident in




which plant life was damaged near a factory manufacturing




alkali (see Section 2.3.2).  Their studies demonstrated that




damage to plants from hydrogen chloride resulted from the direct




action of the gas itself on the above-ground parts of the plants




and not from the conversion products produced in the soil.  Fumi'




gation experiments with viburnum and larch seedlings indicated

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                                                             8
that approximately 7,500 to 30,000 ug/m3 (5 to 20 ppm) of




hydrogen chloride could kill the plants within 2 days.  More-




over, after 1 day at this concentration, the viburnum leaves




remained rolled up at the edges, withered, shrunk, faded, and




necrotic, even after they were placed in fresh air.  Similar




injuries resulted from chlorine gas, but a higher concentration




of 750,000 i-ig/m3 (500 ppm) was necessary to produce damage.




Hydrochloric acid fumes (approximately 6 percent acid) required




only a few hours to damage the plants, primarily producing bleached




spots on the tips or margins of the leaves.  At low concentrations




of hydrochloric acid (approximately 1 to 10 percent acid), the




plants remained healthy for several days.




       Further experiments showed that a 1-hour exposure to




1,500,000 |-ig/m3 (1,000 ppm) hydrogen chloride produced local



lesions in fir, beech,  and oak leaves.  Marginal leaf scorch




was found on the leaves of maple, birch, and pear trees exposed




to hydrogen chloride.  Tipburn of the fir needles resulting from




two exposures to 1,500,000 ag/m3 (1,000 ppm) was still visible




3 weeks later.  The experiments also indicated that spruce was




not visibly affected at daily 1-hour exposures to 3,000,000




ug/m3 (2,000 ppm) hydrogen chloride for 80 days.  However,




recent studies by Lacasse^l showed that spruce seedlings died




from exposure to less than 50 ppm of hydrogen chloride for only




20 minutes.




       Hydrogen chloride injury in broad-leaf plants is indi-




cated by a marginal leaf burn that progresses basipetally with

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                                                             9
prolonged exposure .^2   In grasses, the tips become brown-




colored after exposure to low concentrations.  The threshold




concentration for plant marking was suggested to be generally




75,000 to 1,500,000 ng/m3 (50 to 100 ppm) hydrogen chloride,




but these values were obtained with no air circulation over




the plants.  Thomas107 found that the marking threshold for



sugar beets was a few hours' exposure at 15,000 i-ig/m3  (10 ppm).



       Lacasse _et_ aJ^.62,74,93 have recently studied the effects




of low concentrations of hydrogen chloride on plants.  Tomato




plants were exposed to 7,500 ng/m3 (5 ppm) hydrogen chloride




for 2 hours at 31°C, with a relative humidity between 65 and




75 percent, and a light intensity of 3.9 X 104 ergs/cm2-sec.



The leaves developed interveinal bronzing and bleaching, fol-




lowed by necrosis, within 72 hours after exposure.  The middle-




aged leaves were affected more severely than the younger leaves.



Furthermore, the hydrogen chloride-exposed plants contained 300




percent more chloride than the unexposed control plants.  The




immature leaves showed the greatest increase in chloride, while




the roots and stems showed little or no significant increase.




The increase in chloride was not found beyond 24 hours.  In




fact,  there was a slight decrease in chloride content after




the first 24 to 72 hours.




       Experiments were also conducted to determine the thresh-




old for visible damage of 12 species of coniferous and broad-



leaf seedlings. "74  ip-^g experimental conditions were as follows:




exposure to 4,500 to 64,500 |-ig/m3 (3 to 43 ppm) hydrogen chloride

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                                                              10
for 4 hours at 27°C, relative humidity between 78 to 85 percent,




and light intensity of 1.4 X 104 ergs/cm2-sec.  A summary of




the threshold values determined by these experiments is given




in Table 5 in the Appendix.  The results indicate that the




coniferous plants were more resistant to incipient injury than




the broadleaf plants.  Symptoms found in the broadleaf plants




included marginal and interveinal necrosis and necrotic flecking.




The only symptom observed for the coniferous species was tip




necrosis.  The period of time for the first appearance of injury




varied between 8 and 24 hours.



       Lacasse^2 found that the relative humidity of the sur-




rounding area is a very important factor in the damage to plants




exposed to hydrogen chloride.  Thus, when the relative humidity




was increased from 40 to 65 percent, the rate and severity of




damage was observed to suddenly increase.




       Thomas    reported in 1951 that hydrogen chloride is less



toxic to plants than sulfur dioxide.  Plant responses at high




concentrations of hydrogen chloride may resemble acute sulfur




dioxide injury.




       A summary of the reported effects of hydrogen chloride




on plants is given in Table 5 in the Appendix.




2.3.2  Incidents of Plant Damage



       Hindawi ° reported recently that emissions from a glass




manufacturing factory injured shrubs, trees, and plants in the




surrounding area.  Specimens severely injured included maple




and cherry trees, rose bushes together with the buds, and begonias,

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                                                             11
Factory stack emissions analyzed after the incident contained




178,500 to 709,500 |ag/m3 (119 to 473 ppm) hydrochloric acid




and 1,560 to 2,760 |Jg/m3 (0.52 to 0.92 ppm) chlorine.  Analy-




sis of injured silver maples showed a chloride content of




4,700 ppm, compared to 3,800 ppm for uninjured silver maple




trees.




       Although no other incidents in the United States have




been reported, several other countries have reported damage



to plants from exposures to hydrochloric acid.  The best-known




case happened in England. °7  Extensive damage to plants occurred



near a factory that used the Leblanc soda process to make alkali




and emitted hydrogen chloride as an unwanted by-product.  Between




1836 and 1863, scrubbers were installed at various alkali factories




which removed 95 percent of the hydrogen chloride in the emis-



sions so that less than 450 ng/m3 (30 ppm) of hydrogen chloride




remained in the stack effluent.  This control eliminated the




plant damage.




       Bohne13 reported two examples of damage to plants by emis-



sions of hydrogen chloride from incinerators of nearby hospitals.




These incinerators were burning 80 to 90 percent paper and card-




board packing material.  In one case, incineration for only 2 to




3 hours per day, 5 days a week, completely ruined the plants in




a nursery located 450 meters from the incinerator.




2.4  Effects on Materials




       In the literature reviewed, no information was found de-




scribing corrosion or damage to materials from exposure to

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                                                             12
environmental concentrations of hydrochloric acid.  However,




it is well-known that hydrochloric acid mists and solutions




are extremely corrosive to most metals and alloys.49,75




Mellor^S has summarized 24 studies on corrosion of various




forms of hard and mild steel and cast iron by hydrochloric




acid.  He noted that corrosion of cast iron and steel increases




regularly as the concentration of the acid increases.




2.5  Environmental Air Standards




       The American Conference of Governmental Industrial Hygien-



ists (ACGIH) has adopted 7,000 ug/m3  (5 ppm)  as the threshold




concentration for hydrogen chloride for an 8-hour day, 5-day



week .HI




       West Germany has also established 5 ppm as the permis-




sible work-station concentration. 5  West Germany has also




established an ambient air quality standard of 0.5 ppm (approxi-




mately 700 Ug/m3 ) of hydrogen chloride for a 30-minute mean




average, with a maximum of 1.0 ppm (1,400 ug/m3) of hydrogen



chloride for a 30-minute mean average. 5




       Russia has established 15 ug/m3 (0.009 ppm) as a 24-




hour maximum average for ambient air concentration of hydrogen




chloride and a maximum of 50 Ug/m3 of hydrogen chloride (0.03



ppm) for a single exposure.^5,73.   The standard for a 24-hour




average is below the concentrations which might cause reflexive




reaction of the sensory organs.




       Czechoslovakia has established a maximum ambient air con-




centration which is different from that of Russia.  The 24-hour

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                                                              13
mean was set at 0.02 ppm, with a one-time exposure maximum of



0.07 ppm.84

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                                                                 14
3.   SOURCES




           Hydrochloric acid may be emitted from a wide variety




    of sources.  Emissions from some sources may go unnoticed




    because the hydrochloric acid is generated as an unpredicted




    product.  The sources may be classified as follows:




           (1)  Direct manufacturing of hydrochloric acid (e.g.,




    acid-salt and synthesis processes),



           (2)  A predicted by-product of a chlorination process




    in indirect manufacturing (e.g., by-product process),




           (3)  Unpredicted or undesired product of a manufacturing




    process (e.g., thermal decomposition of chloride-containing




    reactants or products),



           (4)  Use of hydrochloric acid in the production or manu-




    facturing of other products (e.g., pickling of metals),




           (5)  Burning or combustion of chloride-containing materials




    (e.g., fossil fuels, plastics, paper),




           (6)  Heating of chloride-containing materials (e.g.,




    heating of organic matter).




           The first two are described in Section 3.2 as production




    sources.  The fourth source is discussed in Section 3.3 as a




    product source.  Those remaining are discussed in Section 3.4




    as other sources.



           In a study'    of air contaminant emissions in Niagara




    County, N.Y., it was found that 4,083 tons of hydrogen chloride




    were emitted into the atmosphere per year.  Of this total, 2,911




    tons originated from processing plants and 1,172 tons from the

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                                                             15
consumption of coal and oil for heating purposes.   Table 6  in




the Appendix lists the total emissions by urban areas within




the county-




3.1  Natural Occurrence




       Natural occurrences of hydrochloric acid are rare.




Almost all of this acid, particularly as an atmospheric pollu-




tant, is produced by man, either from manufacturing processes




or burning or heating of chloride-containing substances.  Minute




quantities of hydrochloric acid are present in nature in volcanic




fumes and in some rivers. 58  Qf course, it is also present in the




gastric juices of the body.




3.2  Production Sources



       In the United States, hydrochloric acid is produced by




three processes:7'50'106   (1)  the by-product process from



chlorination of organic compounds, (2)  reaction of chloride




salt with sulfuric acid, and (3)  synthesis via reaction between




chlorine and hydrogen gas.  In 1934,  86 percent of the production




of hydrochloric acid was by the salt-acid process, 14 percent by




the synthesis process, and none from the by-product process.91




However, in recent years, the by-product process has become the




major production source, accounting for over 84 percent of the



hydrochloric acid production in 1967.23   This process has also




shown a continuing growth pattern (see Table 7 in the Appendix).




In contrast, the other two processes have shown very little




increase over the past few years.  A more detailed description




of these processes can be found in other references.7'58'88'106

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                                                             16
       According to 1962 data,88 60 plants use the by-product


process, 22 plants use the synthesis process, and 15 plants use


the salt-acid process.  However, there are a total of only 88


plants producing hydrochloric acid, since some plants use more


than one process.  Production by State and process is given in


Table  8  in the Appendix.  The major producers of hydrochloric


acid are listed in Table  9 in the Appendix.


3.2.1  By-Product Process


       The major commercial source of hydrochloric acid is the


chlorination of organic compounds by chlorine gas.  Thus, in


any manufacturing process  in which chlorine gas is used to


replace hydrogen with chlorine in a compound, hydrogen chloride


is produced as a by-product.  Examples of such processes are


the preparation of carbon  tetrachloride using methane (Equation 1)


and of chlorobenzene using benzene (Equation 2).  The chlorination


process may be used to prepare a desired end product, such as


carbon tetrachloride or chlorobenzene, or may be used to pre-


pare an intermediate for a non-chloro-containing end product,


as in the preparation of phenol from benzene using chlorobenzene


(Equations 2 and 3).


       CH4 + 4C12 	> CC14 + 4HC1               ,      .     ,
(Methane)                      (Carbon tetrachloride)    t^uation j.;



       CsHs + Cla	> CSH5C1 + HC1              (Rmiatinn 7)
(Benzene)                      (Chlorobenzene)           liquation 2)



       CSH5C1 + NaOH 	> C6H5OH + NaCl             (Fnn^inn ^ >
(Chlorobenzene)                (Phenol)                  (Equation 3)



Therefore, it is not possible to determine from the end products

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                                                            17
of a company whether by-product hydrochloric acid is being




produced if one is not familiar with each of the processes




used to obtain the final product.  Numerous chlorinated and




nonchlorinated organic compounds are made in which hydrogen




chloride is evolved as a by-product.  In fact, approximately




70 percent of the chlorine produced today is used in the manu-




facture or preparation of organic compounds.   The ever-




increasing use of chlorinated organic compounds is reflected



in the production of hydrochloric acid using by-product



recovery (see Table 7 in the Appendix).




       The effluent gas from the chlorination of an organic




compound contains not only hydrogen chloride but also various




amounts of air, chlorine gas, and organic products, depending




on such factors as initial organic reactant and conditions




used.  Therefore, the recovery system for the hydrogen chlo-



ride or hydrochloric acid varies with the nature of the other



impurities present in the effluent gas.  For example, if the




organic contaminants are low-boiling, the hydrogen chloride




is removed first by means of a water absorption system (see




Section 4).  On the other hand, if the organic impurities are




high-boiling, they are removed by condensation before the hydro-




gen chloride is absorbed.  To obtain anhydrous hydrogen chloride,




the effluent gas is fed into a condenser or distillation appa-




ratus for separation of the different products.  Several recovery




systems are reported in the literature.16'47'63'77'98  Normally,




the hydrochloric acid produced by this method contains organic




impurities and may require further purification.

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                                                            18
       Although hydrochloric acid produced as a by-product is




collected for use and sale by some companies, in other cases




the acid emissions may only be treated to avoid air pollution;




and in still others, nothing may be done about the emissions.




3.2.2  Salt-Acid Process




       In this process, common salt (sodium chloride,  NaCl)



is reacted with sulfuric acid (60° or 66° Baume).   The reac-




tion takes place in two steps:  first, hydrogen chloride and




sodium acid sulfate are formed,  and second, sodium acid sul-




fate is further reacted with sodium chloride to yield more




hydrogen chloride and sodium sulfate (normal sulfate).  (See




Equations 4 and 5.)  In cases in which sodium acid sulfate is




available—-e.g., as a by-product in the manufacture of nitric




acid—the acid sulfate is used directly as shown in Equation 5.




       NaCl + HSS04	»NaHSO4 + HC1        (Equation 4)




       NaHSO4 + NaCl	»Na2SO4 + HC1        (Equation 5)




       Generally, the salt and a slight excess of acid are




heated to 1,400 to  1,600°F in a Mannheim oven.  The reactants




are continuously fed into the center of the furnace, and the




salt cake that forms is removed at the periphery,  where it is



discharged continuously through a chute for transfer to storage,




The effluent gas contains 30 to 70 percent (by volume) hydrogen




chloride, as well as salt dust,  air, and small traces of chlo-




rine.  This gas is  passed through dust removal equipment, such




as settling chambers or cyclones, and then cooled to approxi-




mately 100°F by means of tube coolers or packed towers.50,58

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                                                           19
A further purification system, usually coke filtering, is




used to remove sulfuric acid mist and the remaining fine dust




particles.  After this final step, the hydrogen chloride is




collected by absorption methods described in Section 4.



       One of the major producers of hydrochloric acid in



the United States uses the Hargreaves process.58,92  jn this




process the salt, sodium chloride, is reacted directly with




sulfur dioxide in the presence of steam and air  (Equation 6).




The sulfur dioxide, obtained by burning sulfur, is passed




into a series of vertical chambers which have perforated trays




for the salt.  The system is designed so that the sulfur diox-




ide stream is first passed through a chamber containing nearly




spent salt and lastly through a chamber containing the raw




salt.  The system temperatures vary from 1,000°C initially to




800°C in the final chambers of raw salt.  The end gas then is




passed through the absorption system to obtain the hydrochloric




acid.




       4NaCl + 2S02 + O3 + 2H20	>2Na3SO4 + 4HC1  (Equation 6)



       Hydrogen chloride emissions from the salt-acid process




are higher than those from either of the other two processes.




In the Mannheim furnace operations, losses of hydrogen chlo-




ride can occur through leaks at the furnace, removal of hot




salt cake, or from the tail gas emissions. 1' ^2  jn ^he more




modern furnaces, emissions are controlled by use of an exhaust




fan installed after the absorber system to maintain the pres-




sure slightly below atmospheric level at the furnace; the hot

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                                                           20
salt cake is also precooled in a water-cooled screen conveyor



before dumping.  However, if large leaks occur in the system,



the system becomes blocked, or the exhaust fan fails, the



furnace can lose its draft, and emissions into the atmosphere



can occur around the furnace, particularly at the doors and



at the salt cake discharge. -*0   Short periods of emissions



can occur if the furnace door is opened to break up large



lumps of salt that interfere with proper operation of the



furnace.



      Emissions resulting from upsets in the hydrogen chlo-



ride absorption system, which is common to all three processes,



are discussed in Section 4.



3.2.3  Chlorine-Hydrogen Synthesis



      The advantage of the chlorine-hydrogen synthesis process



is that a hydrochloric acid is produced that is very pure,



depending on the purity of the reactants.  In this process,



chlorine is burned in a slight excess of hydrogen in a reac-



tor or combustion chamber.50,106  T^Q resulting product is



98 to 99,7 percent pure.106  Since a mixture of hydrogen and chlo-




rine is explosive, several safety provisions are incorporated



into the system, which is completely enclosed.  Thus, there is



very little emission of hydrogen chloride in this process.



The product gas is passed through a gas-cooling system and then



an absorption system similar to that used for the salt-acid



process to give hydrochloric acid.  If hydrogen chloride is



desired, only gas-cooling equipment is necessary-

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                                                             21
3.3  Product Sources



       Hydrochloric acid and hydrogen chloride have a wide



variety of uses;58'^6 major uses are in the manufacture of



organic and inorganic chemicals, production of metals, the



cleaning of metal and other materials,  food processing, and



acidification of oil wells.  The consumption of hydrochloric



acid for these uses in 1963 is given in Table 10 in the Appen-



dix.  The consumption by certain industries for 1958 and 1963



is given in Table 11 in the Appendix.  As shown by the latter



table, the demand for hydrochloric acid is increasing (see also



Table 7, Appendix).  The use of hydrochloric acid in steel pick-



ling, vinyl plastics, oil well acidizing, and industrial cleaning



and chemical products is also increasing.



       However, even with the growing demand, there has been an



oversupply of hydrochloric acid in recent years.58'88  This fact,



plus the increase in stream pollution by the acid, has made dis-



posal of hydrochloric acid an expanding problem.  One possible



solution for the oversupply problem is the use of hydrochloric



acid to manufacture chlorine.58  According to reports by trade



sources, the oversupply has shown a gradual decline.20



3.3.1  Manufacture of Chemicals



       Nearly half of the hydrochloric acid produced is used in



the manufacture of organic chemicals, such as chlorinated organic



compounds, including the manufacture of alkyl chlorides from



olefins and chlorides from alcohols.  It is also used in



the presence of oxygen (oxyhydrochlorination) to prepare

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                                                           22
polychlorinated alkyl compounds and chlorinated aromatic




compounds.  Other uses occur in the production of dyes and




dye intermediates and in the preparation of pharmaceutical




chemicals, such as various amine hydrochloride salts, aconi-




tic acid, adipic acid, and citric acid.  In the production




of chlorinated polymers, hydrochloric acid is used in the




preparation of intermediate monomers, such as chloroprene



and vinyl chloride.  In addition, it is used as a solvent




and a catalyst in organic reactions involving isomerization,




polymerization, and alkylation.



      Only about 5 percent of the hydrochloric acid pro-




duced is used for preparing inorganic chemicals, such as




metal chlorides, alumina, phosphoric acid, titanium dioxide,




silica gel, and paint pigments.58'76'88'96  Recently, hydrochloric




acid has been used to manufacture chlorine by electrolysis or




oxidation methods.



3.3.2  Metal Production




      Metal production consumes approximately 17 percent of




the hydrochloric acid produced.  It is used in many metallur-




gical extraction processes for treating various high-grade




ores, including those which yield germanium, manganese, radium,




tantalum, tin, and vanadium.  Hydrochloric acid is also being



considered as a substitute for sulfuric acid in treating low-




grade ores.  The Dron process for obtaining magnesium from




seawater uses hydrochloric acid.  This acid is also used as




an etching medium for chemical milling of metals such as alu-




minum, magnesium, steel, and titanium.

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                                                           23
3.3.3  Other Uses



      Another major use, accounting for approximately 18 per-



cent of the production of hydrochloric acid, is in the Dowell



process for activating petroleum wells.  Inhibited hydrochlo-



ric acid is used to improve oil well porosity and well flow



or production by acidizing the formation.



      Approximately 7 percent of the hydrochloric acid pro-



duced is used primarily for pickling and cleaning metal prod-



ucts and removing oxides and scale from boilers and heat-



exchange equipment.



      A small amount of hydrochloric acid is used in food



processing, including hydrolysis of proteins and starch in



the preparation of dextrose and starch syrups, manufacture



of monosodium glutamate, and reactivation of bone char and



charcoal in sugar refining.



      It is also used in chlorinating and reclaiming rubber,



coagulating latex, fluxing babbitt metals, detanning hides



following depilation, and etching airport runways in prepara-



tion for resurfacing with bonded concrete.  It is also an



ingredient in tanning and dye liquors.



3.4  Other Sources



      Atmospheric emissions of hydrochloric acid result from



a large number of sources other than the manufacture and use



of this acid.  These other sources include heating or burning



of chloride-containing materials in the presence of organic



compounds or other hydrogen-containing substances.  Chlorides

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                                                          24
are also widespread in nature and in many natural products.



Moreover, many manufactured products contain chloride, such



as polyvinyl chloride plastics.  When these materials are



burned, incinerated, or perhaps just heated, hydrochloric



acid can be evolved as a predicted or unpredicted product.



The examples discussed in this section give an indication of



some of the possible emission sources.



3.4.1  Coal



      Burning coal may be one of the major contributors to



hydrochloric acid air pollution.  Chlorine is present in coals,



mostly in the form of inorganic chloride salts27 that are solu-



ble in water.22  when coal burns, most of the chloride salts



are converted to hydrogen chloride,^'*^° which is then emitted



into the atmosphere.



      Analysis of United States coals shows that the chlorine



content ranges from 0.01 to 0.56 percent.I/51'78»89  Table 12



in the Appendix indicates the chlorine content of some



selected coals in the United States.  The Central and Appala-



chian areas, which have high-chlorine-content coals, are also



the areas which consume most of the coal for heat and energy.51



      Piper and Van Vliet8^ found that in burning coal con-



taining 0.066 percent chlorine, 49 ppm of hydrogen chloride



were emitted at the stack, meaning that 60 percent of the



chlorine originally in the coal was converted to hydrogen



chloride.  lapalucci, Demski, and Bienstock^l performed



experiments with pulverized coal containing 0.1 to 0.4 percent

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                                                           25
chlorine at carbon combustion efficiencies of 94 to 98 per-
cent.  Under these conditions, they found that 93 to 98
percent of the chlorine was emitted as hydrogen chloride
and the remainder left in the ash.  To verify these results
under actual conditions, the stack of a local power plant
was sampled after burning a bituminous coal containing 0.087
percent chlorine,,  Analysis showed that only 1.5 percent of
the chlorine was retained in the ash, and the balance was
emitted in the stack gas as hydrogen chloride.
      Furthermore, the amount of hydrochloric acid pollution
by burning coal may be increased when calcium chloride is
added to the coal as an antifreeze or dust-proofing agent.53
      A potentially large amount of hydrochloric acid pollu-
tion may result from coal burning.  For example, it is esti-
mated that 671 million short tons of bituminous coal will be
consumed in 1975.H   Assuming that the average chlorine con-
tent of the coal is 0.2 percent and that 95 percent of this
is converted to hydrochloric acid, then approximately 1.3
million short tons of hydrochloric acid will be produced
from coal burning in 1975.  For comparison, manufacture of
hydrogen chloride and hydrochloric acid was 1.6 million short
tons in 1967. 3   lapalucci, Demski, and Bienstock^l estimated
on a similar basis (i.e., 0.2 percent chlorine coal) that an
800-MW power plant will emit from the stack 11,300 standard
cubic feet of hydrogen chloride each hour, or 4,560 tons each
year.

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                                                           26
3.4.2  Fuel Oil




      Fuel oils contain small amounts of chlorides and can




therefore emit hydrogen chloride when burned.  A recent study




on fuel oils   cited two 1938 reports on chloride emissions.




In one report-^-® the chloride content of the ash was given as




0.1 and 4.6 percent by weight for oils found in Kansas and




Texas, respectively.  The other report-^-^ indicated that the




maximum hydrogen chloride content in emissions was approxi-




mately 46 ppm in the stack gas, or approximately 1 pound per




1,000 pounds of oil.  It has been reported that 500 pounds




of hydrogen chloride per day per 100,000 persons is produced



by using oil for domestic heating.30  in comparison, the value




is four times higher for domestic heating using coal.




3.4.3  Automobile Exhaust




      Gasolines which contain tetraethyl lead (TEL), tetra-




methyl lead (TML), or other lead additives also usually con-




tain ethylene chloride or ethylene bromide.  These organic




halide compounds are used as lead scavengers; that is, these




halides will react with the lead to form volatile lead halides




which can be emitted with the exhaust gases and, therefore,




prevent lead deposits in the automobile engine.  An example




of an additive mixture for gasoline is given in Table 1.

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                                                           27
                         TABLE 1

       "ETHYL" ANTIKNOCK COMPOUND-TEL MOTOR 33 MIX101
                                          Weight
     Compound	(percent)

     Tetraethyl lead                       57.5

     Methyl cyclopentadieny-
        manganese tricarbonyl               7.0

     Ethylene dibromide                    16.7

     Ethylene dichloride                   17.6

     Other (dye, inerts)                    1.2
      During gasoline combustion, hydrogen chloride or hydro-

chloric acid can form and be emitted into the air.  Rose ^

feels that hydrochloric acid is present in automobile exhaust

but did not know of any quantitative data available.  He men-

tioned that the exhaust condensates were very acidic, about

pH 2.

3.4.4  Burning of Chloride-Containing Plastics

      Several of the plastics used today contain organically

bound chlorine; examples of some of the more common ones are

polyvinyl chloride (approximately 57 percent chlorine), poly-

vinylidene chloride (approximately 73 percent chlorine), and

neoprene (approximately 40 percent chlorine).  In addition,

organic chlorides are added to other types of plastics and

materials as fire-retardants.  Chloride-containing plastics

are used in making plastic films, containers, seat covers,

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                                                           28
wire insulation, and many other materials.  When these chlo-
ride plastics are heated or burned, hydrogen chloride is
evolved.12'18'54,71,81 studies have been conducted with poly-
vinyl chloride films12'81 to determine the type and quantity
of gases evolved.   In one investigation,12 a sample was heated
at a rate of 3°C per minute; upon reaching 280°C a rapid
weight loss started and continued until about 300°C.  During
this period a 60 percent weight loss was found, and analysis
showed that almost  all the chloride had been evolved as hydro-
gen chloride.  In another study,81 it was found that hydrogen
chloride evolved at 100°C; moreover, the rate of evolution
depended on the  length of the heating period.  The rate of
hydrogen chloride evolution for 1 hour at 100°C was 8,000
|ag/m3 ; after 2 hours, 12,000 |ag/m3 ; and after 3 hours, 20,000
|_ig/m3 •
      Thus, open burning or incineration of chlorinated plas-
tics is a probable  source of hydrochloric acid pollution.
Without effective control measures, this problem will inten-
sify with the increased use of plastics projected for the
future.
3.4.5  Burning of Paper Products
      Analysis of paper products  indicates that the chloride
content is low,10*'13 approximately 0.03 to 0.16 percent by
weight.  Nevertheless, two examples cited in the literature
demonstrate that the amounts of hydrochloric acid emissions
from the incineration of paper can cause injury to plants.13

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                                                          29
In both examples  (see Section 2.3.2), the plant injury was

caused by hydrochloric acid emissions from a hospital incin-

erator burning trash consisting of 80 to 90 percent paper

products.  Additional studies indicated that 53 to 95 percent

of the chloride in paper products is lost on heating at 900°C.

3.4.6  DDT Production

      DDT (dichlorodiphenyltrichloroethane) is a common pesti-

cide manufactured from chloral, chlorobenzene, and sulfuric

acid2  (see Equation 7).
                            H2SO4
       CClgCHO +  2CSH5C1	» CC13CH(C6H4C1)2 + HSO
        (Chloral)                                  (Equation 7)


As seen from the  reaction equation, hydrochloric acid is nei-

ther a reactant nor a product of the desired reaction.  How-

ever, the primary contaminate in the emissions is hydrochloric

acid from decomposition of chloral.  The total amount of ef-

fluent gases has been estimated as about 1 percent of the

weight of DDT produced.

      This is an example of a manufacturing process in which

hydrochloric acid is considered neither a reactant nor a prod-

uct but, nevertheless, is part of the effluent gas stream.

In this case, the hydrochloric acid emissions are due to the

decomposition of the chloride compounds used in the reaction.

3.4.7  Lemon Pulp Extraction

      One company has reported on the extraction of lemon pulp

with isopropyl alcohol at 120°F.   Besides the predictable

emissions of the alcohol, the effluent vapor also contained

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                                                           30
hydrochloric acid droplets.  In this case, the company was



aware of the content of the emissions and used an appropriate



treatment system to control the emissions.



      Although probably only a very minor source, this repre-



sents an example of the heating of organic matter at a low



temperature (120°F) with the evolution of small quantities



of hydrochloric acid.



3.5  Environmental Air Concentrations



      No information has been found on environmental air con-



centrations of hydrochloric acid.  However, Gorham40 observed



that in Great Britain, precipitation samples from urban areas



exhibited a distinct correlation between chloride content and



acidity in samples of pH less than 5.7.

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                                                               31
4„   ABATEMENT



          The high solubility of hydrogen chloride in water and



    the low vapor pressures of even 20 percent hydrochloric acid



    solutions make collection of hydrogen chloride in water an



    effective and inexpensive method of control.



          Thus in the manufacture of hydrochloric acid (or hydro-



    gen chloride)/ the emission control system, which is also part



    of the system for obtaining hydrochloric acid from the hydro-



    gen chloride, consists mainly of water absorption facilities.



    Different types of absorbers are used, but the systems gen-



    erally consist of a packed tower or a cooling absorption



    tower followed by a packed tail tower .->0 ' 58f106  r^e pac;keci



    tower systems-^-58  normally include a connected set of S-



    bend tubes, followed by one or more towers in series.  Cold



    water is added at the last or tail tower and flows over into



    the previous tower.  The concentration of hydrochloric acid



    in this water is thus increased from tower to tower until



    it reaches the S-bend tubes, where the acid solution attains



    its final strength.  However, the packed tower systems are



    rapidly being replaced by cooled absorption systems because



    the latter are more efficient, economical, and compact.  The



    cooled absorption tower designs may consist of either a



    countercurrent or co-current flow of gas and water.  One type



    uses water-jacketed packed tantalum towers with countercurrent



    flow.     The most common system is the co-current falling film



    absorbers.49,58,59   jn this system, gas and weak acid solution

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                                                           32
from the packed tail tower flow downward over vertical,



water-cooled, wetted-wall columns.  Where anhydrous chloride



is the desired product, absorption systems are not used.50



      It has been reported that the use of water scrubbing



systems can reduce the emissions to less than 0.1 pound of



hydrogen chloride per ton of acid produced, although emis-



sions can be 30 times that amount with less effective equip-




ment.7  According to Faith et _al. ,31 hydrogen chloride



emissions can be reduced to a range of 0.1 to 0.3 percent



by volume by the use of two or more tail towers in series.



The emissions of hydrochloric acid may be high if an upset



occurs in the absorption system due to either improper tem-



perature control or insufficient feed water.106



      Other systems that appear to be effective for the con-



trol of hydrochloric acid or hydrogen chloride emissions are



the rotary brush scrubber^ anc| the ejector venturi scrubber.



With the former system, collection efficiencies of 99.995 per



cent have been reported with an initial hydrogen chloride



content of 610 g/m3.  In the latter system, scrubbing effi-



ciency as high as 99 percent has been given for a single-



stage unit for fumes containing up to 20 percent hydrogen



chloride.  The high solubility of hydrogen chloride in water



accounts for the high degree of efficiency of these systems.



      Dry solid adsorbents have also been studied for removal



of hydrogen chloride vapors.9'7!  Adsorbents investigated



include chromium oxinate  and basic salts36 such as Beralyme,

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                                                           33
soda lime, lithium carbonate, and silica-alumina mixtures.



Chromium oxinate or tris-(8-hydroxyquinolinato)chromium(III)



exhibited physical adsorption with anhydrous hydrogen chlo-



ride, but the adsorbing bed showed a tailing effect a long



time before the exit gas concentration reached the entering



concentration.



      Studies by lapalucci, Demski, and Bienstock^l indicate



that hydrochloric acid emissions from coal burning can be



reduced by adding basic salts, such as sodium carbonate,



potassium carbonate, calcium carbonate, and dolomite.  Chlo-



rine retention in the ash when a small amount of basic salt



was added was 8.8 to 37.8 percent, compared to 7.9 percent



without an additive.

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                                                               34
5.   ECONOMICS




          No information has been found on the damage costs or




    economic losses due to the effects of hydrochloric acid air




    pollution on humans, animals/ plants/ or materials.   In




    addition, no information has been found on the economic




    costs of abatement (installation and operation costs of




    control equipment and cost benefits of usable emissions).




          Data on the production and consumption of hydrochloric




    acid are presented in Section 3.

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                                                               35
6.  METHODS OF ANALYSIS
          All of the common methods of analysis for hydrochloric
    acid in air depend upon (1) measurement of acidity, (2) mea-
    surement of chloride ions/ or (3) combination of the two
    measurements.  Therefore,  other strong acids (e.g., sulfuric
    acid, nitric acid) or other chloride salts (e.g., sodium chlo-
    ride) can cause serious interference.
    6.1  Sampling Methods
          In most methods, hydrochloric acid is collected in
    impingers containing water.4'25'105 The high solubility of
    hydrochloric acid in water yields excellent absorption effi-
    ciency. 66
          The results of one investigation indicate that certain
    phosphate salts, particularly silver phosphate, have a high
    collection efficiency for  hydrochloric acid but do  not absorb
    sulfur dioxide.17  However, hydrobromic acid is also absorbed.
          Preliminary studies  indicate that liquid  crystals may
    make effective and selective collection materials for hydro-
    chloric acid and other gaseous  pollutants.33  Acid  mists have
    also been collected on paper,19  gelatinous film,38'68'114 thin
    metal films,67  and metal-coated  glass  slides.43,48
    6.2   Qualitative Methods
          The presence of hydrochloric acid or any  other strong
    acid in air  can be determined by passing the air over moist
    pH indicators such as methyl orange, congo red,  or  blue lit-
    mus  papers.   Hydrochloric  acid or other chlorides can also

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                                                           36
tie detected by bubbling the air through water and adding


silver nitrate.  Depending on the concentration of chloride,


the solution may show a slight turbidity, or yield a white


to grayish precipitate which will not change on addition of


nitric acid but will dissolve or disappear upon addition of


ammonia.


6.3  Quantitative Methods


      In the absence of other strong acids, hydrochloric acid


samples which have been collected in water may be determined


quantitatively by the usual direct titration methods with

                oc
standard bases.


      A spectrophotometric method for determination of strong


acids has been reported.  9/0  After the air sample is passed


through water, methyl red is added to the acidic solution and


the optical density at 530 mp. is determined.  Normal concen-


trations of carbon dioxide and 1,000 Pg of sulfur dioxide per

 2
m  of air do not interfere.


      The size and quantity of acid mists have been deter-


mined by the use of both gelatinous films 38,68,114  an<^ metal-


coated glass slides.43'48  The latter method is not affected


by relative humidity.  Through use of an electron microscope,


it is possible to detect acid droplets with diameters of less


than 0.1 p..48


      In the absence of soluble chloride salts, hydrochloric


acid samples dissolve in water and may be determined by the


standard methods for chloride determination,"  including the

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                                                            37
Mohr method,99'100  absorption indicator method,32'60 and
the modified Volhard method.    These methods have a sensi-
tivity of approximately 18,000 |jg of chloride per liter.
For very small amounts of chloride in air, the determination
can be made turbidimetrically or nephelometrically.2^'^9/"
The hydrochloric acid solution is treated with silver nitrate
and the turbidity determined spectrophotometrically; sensi-
tivity is in the microgram range.  Recently, a method has
been developed for determining chloride colorimetrically.   '
This method is based on the yellow color produced by the iron(IH)
chloro complex in perchloric acid with a sensitivity of
approximately 1,000 ng/m3  of chloride.  This method suffers
from interference from mercury and sulfate ions and is af-
fected by the relative humidity of the air.  There is a
neutron activation technique for determining chloride in
particulates with a sensitivity of approximately 0. 06 |j.g/m3 ,56
      An automated analysis method for chloride is used by
the National Air Sampling Network.110  This method is based
on the reaction of chloride with mercury thiocyanate to yield
thiocyanate ions.  Thiocyanate ions react with ferric ions to
form the stable red complex, hexacyanatoferrate ion, which can
be determined spectrophotometrically at 460 m[a.  The relative
standard deviation for chloride is 1.0 _+ 0.1 |ag/mlo
      Since air samples usually contain other acids as well
as chlorides, these methods are not generally applicable.
There are no methods available that are free from interference

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                                                           38
by all other possible pollutants.  However, an air sample



containing a mixture of sulfur oxides, hydrochloric acid,



and other chlorides can be analyzed by combining the methods



reported in two papers.^'105 The air sample is passed through




an aqueous solution of hydrogen peroxide.  The aqueous solu-



tion is then divided into three parts for three separate



analyses:  sulfate, chloride, and hydrogen ion.  From these



results the amount of each component can be determined.

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                                                               39
7.  SUMMARY AND CONCLUSIONS




          Hydrogen chloride reacts rapidly with the moisture in



    the air and is generally found in the ambient atmosphere as



    hydrochloric acid.  The acid at low concentrations, 15,000



    to 75,000 Lig/m3 (10 to 50 ppm) , irritates primarily the



    mucous membranes of the eyes and upper respiratory tract in



    both humans and animals.  Prolonged exposures to low con-



    centrations of hydrochloric acid can also erode the teeth.



    Work is intolerable after more than 60 minutes in atmospheres



    containing approximately 75,000 to 150,000 M.g/m3 (50 to 100



    ppm) of hydrochloric acid.  Higher concentrations (approxi-



    mately 1,500,000 |~ig/m3 or 1,000 ppm) can attack the mucous



    membranes, causing inflammation of the upper respiratory



    system and resulting in pulmonary edema or spasm of the lar-



    ynx, which can be fatal.  A wide variety of plant life is



    susceptible to the toxic effects of hydrogen chloride or



    hydrochloric acid.  Several examples of plant damage due to



    hydrochloric acid emissions have been reported in the litera-



    ture.  The primary effect on plants is a discoloration or



    bleaching of the leaves.  The threshold for visible damage



    was originally reported as 75,000 to 150,000 [ag/m3  (50 to



    100 ppm) of hydrogen chloride.  However, recent studies indi-



    cate that the threshold for many plants is less than 10 ppm



    for 4-hour exposures.  The strong acidic properties of hydro-



    chloric acid make it extremely corrosive to most metals.

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                                                           40
      Some countries have established ambient air quality



standards for hydrochloric acid, including West Germany



(approximately 750 |ag/m3 or 0.5 ppm as a mean 30-minute



average) and Russia (approximately 15 \j.g/m3 or 0.009 ppm



as a 24-hour average).



      The production rate since 1961 has shown a general



increase of approximately 9 percent.  Hydrogen chloride is



produced by three main processes in the United States:  acid-



salt, direct synthesis, and the by-product process from



chlorination of organic compounds.  The latter process, the



major production source, has shown a steady increase.  Many



organic chlorinating processes and other organic processes



involving chlorinated compounds may produce hydrogen chloride



as a by-product, but it may not be economically feasible to



recover the product for other uses.  Hydrochloric acid is



produced by absorbing the hydrogen chloride gas into water.



      Hydrochloric acid (or hydrogen chloride) is primarily



used to manufacture inorganic and organic chemicals, the



latter accounting for almost 50 percent of the production



in 1963.  Other major uses include metal production, oil-



well acidizing, metal and industrial cleaning, and food pro-



cessing.



      Another potential source of emissions of hydrochloric



acid is the heating or burning of chlorinated materials.



The burning of coal appears to be a possible major source of



hydrochloric acid pollution, since the chloride in coal is

-------
                                                           41
converted to over 90 percent hydrogen chloride during the



burning process.  Similarly, the burning of chlorinated



plastics and paper can be an emission source, and possibly



the burning of fuel oil and gasoline as well.



      No information has been found on the concentrations



of hydrochloric acid in the atmosphere.  Hydrogen chloride



emissions from commercial processes can be effectively con-



trolled by the equipment that is available today.  Systems



now in use include packed water scrubbing towers and cooled



absorption towers.  Emissions from coal burning may be de-



creased by the addition of basic salts to the coal before



burning.



      No information has been found on costs for the control



of hydrochloric acid pollution or for costs incurred by damage



to humans, animals, plants, and materials as a result of hydro-



chloric acid emissions.



      No continuous monitoring methods are available for mea-



suring the hydrochloric acid content of environmental air.



The common methods used measure either the acidity or chlo-



ride content of the air sample, and therefore suffer from



interference from other acids and chlorides present in the



environmental air.



      Based on the material presented in this report, further



studies are suggested in the following areas:



      (1)  Determination of the amount of hydrochloric acid



present in the atmosphere of heavily populated areas,

-------
                                                           42
particularly near the source of production and near coal-



burning establishments and incinerators.



      (2)  Evaluation of the effects of low concentrations



of hydrochloric acid on humans, animals, plants, and materials,



      (3)  Determination of the contribution of automobile



exhausts, incinerators, and other combustion sources to hydro-



chloric acid air pollution.

-------
                                                          43
 REFERENCES

 1.  Abernethy, R. p., and F. H. Gibson, Rare Elements in Coal,
     U. S. Bur. Mines Inform. Circ. 8163 (1963).

 2.  Air Pollution Control in Connection with DDT Production,
     J. Air Pollution Control Assoc. 14 (3) :49 (1964).

 3.  Air Pollution—Niagara County (Comprehensive Area Survey
     Report No. 3), New York State Air Pollution Control Board,
     Albany, N.Y. (1964).

 4.  Alekseyeva, M. V., and E, V. Elfimova, Fractional Determina-
     tion of Hydrochloric Acid Aerosol and of Chlorides in
     Atmospheric Air, Giqiena i Sanit. 23 (8) :71 (1958).

 5.  Altman, P. L., and P. S. Dittmer, (Eds.), Environmental
     Biology (Bethesda, Md.:  Federation of American Societies
     for Experimental Biology, 1966).

 6.  Atmospheric Emission from Chlor-Alkali and Related Manu-
     facturing Processes, Joint National Air Pollution Control
     Administration and Manufacturing Chemists'  Association,
     Inc. (To be published).

 7.  Atmospheric Emissions from Hydrochloric Acid Manufacturing
     Processes, Joint National Air Pollution Control Administra-
     tion and Manufacturing Chemists' Association, Inc. (To be
     published).

 8.  Barnebey, H. L., Removal of Exhaust Odors from Solvent
     Extraction Operation by Activated Charcoal Adsorption,
     J. Air Pollution Control Assoc. 15 (9):422 (1965).

 9.  Berkau, E. E., G. T. Fisher, and M. M. Jones, The Influence
     of Axial Dispersion on the Fixed Bed Adsorption of the
     Hydrogen Chloride-Chromium Oxiante System,  Preprint (1964).

10.  Bethge, P. O., and T. Troeng, Determination of Chlorine in
     Wood, Pulp and Paper, Svensk Papperstid. 62 (17):598 (1959).

11.  Bituminous Coal Facts (Washington, D. C.: National Coal
     Association, 1964).

12.  Boettner, E. A., and B. Weiss, An Analytical System for
     Identifying the Volatile Pyrolysis Products of Plastics,
     Am. Ind. Hyg. Assoc. J. 28;535 (1967).

13.  Bohne,  H., Immission Damage Caused by Hospital Waste Incin-
     eration, Staub. (English Transl.) 27(10) :28 (1967)„

-------
                                                              44
14.  Bureau of the Census, U. S. Department of Commerce,
     Washington, B.C. Personal communication (1968).

15.  Caldwell, J. R., and H. V. Moyer, Determination of Chloride,
     Ind. Eng. Chem. 7:38 (1935).

16.  Campbell, D. H., U. S. Patent 2717199 (1948).

17.  Chaigneau, M.,  and M. Santarromana, Dosage de 1'acide
     chlorhydrique en presence d'anydride sulfureux a 1'aide de
     reactifs  solides, Mikrochim. Acta 1965:976 (1965).

18.  Coleman,  E. H., and C. H. Thomas, The Products of Combustion
     of Chlorinated  Plastics, J. Appl. Chem. 4;379 (1954).

19.  Commins,  B. T., Determination of Particulate Acid in Town
     Air, Analyst 88:364  (1963).

20.  Commodity Notes, Chemicals, U. S. Dept. of Commerce (March,
     1968).

21.  Cralley,  L. V., The  Effect of Irritant Gases Upon Rate of
     Ciliary Activity, J. Ind. Hyg. Toxicol. 2_4:193 (1942).

22.  Crumley,  P. H. , A. W. Fletcher.- and D. S. Wilson, The
     Formation of Bonded  Deposits in Pulverized-Fuel-Fired
     Boilers,  J. Inst. Fuel 28(168)ill?  (1955).

23.  Current Industrial Reports, Inorganic Chemicals and Gases,
     U. S. Department of Commerce, Bur. of the Census, Washington,
     D.C. (1962, 1966, 1967).

24.  Demidov, A. V.,  and L. A. Mokhov, Rapid Methods for the
     Determination of Harmful Gases and Vapors in the Air,
     Translated by B. S. Levine, U.S.S.R. Literature on Air
     Pollution and Related Occupational Diseases 10:32(1962).

25.  Devorkin, H. ,  _ejt aJL. , Air Pollution Source Testing Manual,
     Air Pollution Control District,  Loe Angeles County,
     Calif. (1965).

26.  Documentation of Threshold Limit Values,  American Conference
     of Governmental  Industrial Hygienists,  Committee on Thresh-
     old Limit Values,  Rev.  ed. (1962).

27.  Edgcombe, L. J., State of Combination of  Chlorine in Coal-
     Extraction of Coal with Water,  Fuel 35:38 (1956).

-------
                                                              45
28.  Elfimova, E. V., Determination of Limit of Allowable
     Concentration of Hydrochloric Acid Aerosol (Hydrogen
     Chloride) in Atmospheric Air, Giqiena i Sanit. 24(1) :13
     (1959).

29.  Elfimova, E. V., Data for the Hygienic Evaluation of
     Hydrochloric Acid Aerosol (Hydrochloride Gas) as an Atmo-
     spheric Pollutant, Translated by B. S. Levine, U.S.S.R.
     Literature on Air Pollution and Related Occupational Diseases
     9_:18 (1962).

30.  Eliassen, R., Domestic and Municipal Sources of Air Pollution,
     Proc. Natl. Conf. Air Pollution, Public Health Service
     (1958).

31.  Faith, W. L., D. B. Keyes, and R. L. Clark, Industrial
     Chemicals (New York:  Wiley, 1957).

32.  Fajans, K., and H. Wolff, The Titration of Silver and
     Halogen Ions with Organic Dyestuff Indicators, Z. Anorg.
     Allgem. Chem. 137;221 (1924).

33.  Fergasom J. L., _ejt a_l_. ,  Detection of Liquid Crystal Gases
     (Reactive Materials), Westinghouse Electric Corp., Pitts-
     burgh Research Laboratories (Tech. Kept.  RADC-TR-64-569,
     1965).

34.  Ferris, B. G., and N. R.  Frank, Air Pollution and Disease,
     Anesthesioloqy 25:470 (1964).

35.  Flury, F., and F. Zernik, Schadliche Gase (Berlin;  Springer,
     1931).

36.  Gadomski, S. T., Dry-Packed Beds for the Removal of Strong
     Acid Gases from Recycled Atmospheres,  Chemistry Division,
     Naval Research Laboratory, Washington, D.C.,  NRL Rept.
     6399 (1966).

37.  Gaylord, W. M.,  and M. A. Miranda, The Falling-Film Hydro-
     chloric Acid Absorber, Chem. Eng. Prog. 53:139-M (1967).

38.  Gerhard, E. R.,  and H. G. Johnstone, Microdetermination of
     Sulfuric Acid Aerosol, Anal. Chem. 27:702 (1955).

39.  Goldberg, E. K., Photometric Determination of Small Amounts
     of Volatile Mineral Acids (Hydrochloric and Nitric) in the
     Atmosphere, Hyg. Sanitation 31(9):440 (1966).

-------
                                                              46
40.  Gorham, E.,  Atmospheric Pollution by Hydrochloric Acid,
     Quart. J. Rov. Meteorol.  Soc. 84;274 (1958).

41.  Harris, L. S., Fume Scrubbing with the Ejector Venturi
     System, Chem. Enq. Prog.  62(4):55 (1966).

42.  Haselhoff, E., and G. Lindau, Beschadigung der Vegetation
     durch Rauch. (Leipzig:  Verlag von Gebruder Borntraeger,
     p. 203, 1903).

43.  Hayashi, H., S. Koshi, and H. Sakabe, Determination of Mist
     Size by Metal Coated Glass Slide, Bull. Natl.  Inst. Ind.
     Health 6.:35 (1961).

44.  Henderson, Y., and H. W.  Haggard, Noxious Gases (New York:
     Reinhold, 1943).

45.  Heyroth, F.  F.,"Hydrogen Chloride,"in Industrial Hygiene
     and Toxicology, vol. II,  2nd ed., F. A. Patty, Ed. (New
     York:  Interscience, 1963).

46.  Hindawi, I.  J., Injury by Sulfur Dioxide, Hydrogen Fluoride
     and Chlorine as Observed and Reflected on Vegetation in the
     Fields, J. Air Pollution Control Assoc. 18(5)  ;307 (1968).

47.  Hooker, T.,  U.S. Patent 2841243 (1953).

48.  Horstman, S. W., Jr., and J. Wagman, Size Analysis of Acid
     Aerosols by a Metal Film Technique,  Amer. Ind. Hyg. Assoc. J.
     .28:523 (1967).

49.  Hydrochloric Acid, Aqueous and Hydrogen Chloride, Anhydrous,
     Chemical Safety Data Sheet SD-39, Manufacturing Chemists
     Association, Washington,  D.C. (1951).

50.  Hydrochloric Acid Manufacture, Report No. 3,Air Pollution
     Control Association, TI-2 Chemical Committee  (1962).

51.  lapalucci, T. A., R. J. Demski, and D. Bienstock, Chlorine
     in Coal Combustion, Pittsburgh Coal Research Center, U.S.
     Bureau of Mines, in press.

52.  Jacobs, M. B., The Analytical Toxicology of Industrial
     Inorganic Poisons, (New York:  Interscience, p. 140, 1967).

53.  Johnson, A.  J., and G. H. Auth, Fuels and Combustion Hand-
     book, 1st ed. (New York:   McGraw-Hill, 1951).

-------
                                                              47
54.  Kaiser, E. R., and J. Tolciss, Control of Air Pollution from
     the Burning of Insulated Copper Wire, J. Air Pollution
     Control Assoc. 13(1 ):5 (1963).

55.  Katz, M.,  Quality Standards for Air and Water, Occupational
     Health Rev. 17(1);3 (1965).

56.  Keans, J.  R.,  and E.  M. R. Fisher, Analysis of Trace Elements
     in Air-Borne Particulates, by Neutron Activation and Gamma-
     Ray Spectrometry, Atmospheric Environ, 2:603 (1968).

57.  Kear, R. W., and H. M. Menzies, Chlorine in Coal, Its
     Occurrence and Behavior During Combustion and Carbonization,
     Brit. Coal Util. Res. Assoc. Monthly Bull. 20(2) ;53 (1956).

58.  Kleckner,  W. R.,"Hydrochloric Acid,"in Kirk-Othmer Encyclopedia
     of Chemical Technology, vol. 11 (New York:  Interscience,
     p. 307, 1966).

59.  Knott, K.  H.,  and S.  Turkolmez, Krupp Rotary Brush Scrubber
     for the Control of Gas, Vapour, Mist and Dust Emissions,
     Krupp Technical Review (Essen) .2_4(1):25 (1966).

60.  Kolthoff,  I. M., and V. A. Stenger, Volumetric Analysis, 2
     (New York:  Interscience, 1947).

61.  Lacasse, N., Open Burning and Our Forests, A New Threat,
     Forest Notes,  p. 23 (Summer 1968).

62.  Lacasse, N., Plant Pathology, Environmental Division Center,
     Pennsylvania State University, University Park, Pa., personal
     communication.

63.  Latchum, J. W., Jr.,  U. S. Patent 2433996 (1948).

64.  Lehmann, K. B., Arch. Hyg. 5:16 (1886), cited in F. Flury and
     F. Zernik, Schadliche Gase (Berlin:  Springer, 1931).

65.  Leites, R., Arch. Hyg. 102:91 (1929), cited in F. Flury and
     F. Zernik, Schadliche Gase (Berlin:  Springer, 1931).

66.  Leithe, W., and G. Petschl, Comparative Absorption Tests
     for Determination of Gaseous Air Contaminants in Wash
     Bottles, Fresenius' Z.. Anal. Chem. 226(4) ;352 (1967).

67.  Lodge, J.  P.,  and B.  R. Havlik, Evaporated Metal Films as
     Indicators of  Atmospheric Pollution, Intern. J. Air Water
     Pollution  3:249 (1960).

-------
                                                              48
68.  Lodge, J. P., J. Ferguson, and B. R. Havlik, Analysis of
     Micron-Sized Particles, Anal. Chem. 32:1206 (1960).

69.  Machle, W. , _et al_. , The Effect of the Inhalation of Hydrogen
     Chloride, J. Ind. Hyg. Toxicol . 24:222 (1942).

70.  Manita, M. D. , and V. P. Melekhina, A Spectrophotometric
     Method for the Determination of Nitric and Hydrochloric
     Acids in the Atmospheric Air in the Presence of Nitrates
     and Chlorides, Hyq. Sanitation 29(3) ;62 (1964).

71.  Mastromatteo, E. , Health Aspects in Fire Fighting, Firemen
     J33_(6):20 (1966).

72.  Matt, L., Dissertation, Wurzburg, 1889, cited in F. Flury
     and F. Zernik, Schadliche Case (Berlin:  Springer, 1931).

73.  Maximum Permissible Concentration of Harmful Substances in
     Atmospheric Air  in Populated Places, Hyg. Sanitation 29:5
     (1964).

74.  Means, W. E. , Jr., and N. L. Lacasse,  Relative Sensitivity of
     Twelve Tree Species to Hydrogen Chloride Gas, Presented at
     the Annual Meeting of the Northeastern Division, American
     Phytopatho logical Society, University of Massachusetts,
     Amherst, Mass. (Nov. 7-8, 1968).

75.  Mellor, J. W. , Inorganic and Theoretical Chemistry — Suppl. II,
     Part 1 (New York:  Longmans, Green and Co., 1956).

76.  The Merck Index, 8th ed. (Rahway, N.J. :  Merck, 1968).

77.  Meyers, L. A., U. S. Patent 2490454 (1949).
78.  Nelson, H. W. , .§£ ^1. , Corrosion and Deposits in Coal-
     and Oil-fired Boilers and Gas Turbines, American Society of
     Mechanical Engineers (1959).

79.  Pimenova, Z., Absorption of Hydrogen Chloride in Air Analysis,
     Giqiena i Sanit. 13(11) ;31 (1948).

80.  Piper, J. D. , and H. Van Vliet, Effect of Temperature
     Variation on Composition, Foul ing Tendency, and Corrosiveness
     of Combustion Gas from A Pulverized-Fuel-Fired Steam
     Generator, Trans. ASME 80:1251 (1958).

81.  Papov, L. A., and V. D. Yablochkin, Characteristics of
     Gases Released by Polyvinyl Chloride Film, Hyq.  Sanitation
     11:114 (1967).

-------
                                                             49
82.  Ronzani, E., Ueber den Einfluss der Einatmungen von reizenden
     Gasen der Industrien auf die Schutzkrafte des Organismus
     gegenuber den infektiven Krankheiten, Arch. Hyg. 70:217
     (1909).

83.  Rose, A., National Air Pollution Control Administration,
     Public Health Service, U. S. Department of Health,
     Education and Welfare, Cincinnati, Ohio,  personal communi-
     cation (Jan. 1969).

84.  Rossano, A. T. , Analysis and Comparison of Available Data
     on Air Quality Criteria in Member Countries, Inter-Regional
     Symposium on Criteria for Air Quality and Method of
     Measurement; Geneva  (Aug. 1963).

85.  Ryazanov, V. A., New Data on Limits of Allowable Atmo-
     spheric Air Pollutants, U.S.S.R. Literature on Air Pollu-
     tion and Related Occupational Diseases 9;1 (1961).

86.  Ryazanov, V. A., Sensory Physiology as Basis for Air
     Quality Standards, A.M.A. Arch. Environ. Health _5_ :480
     (1962).

87.  Sax, N. I., Dangerous Properties of Industrial Materials
     (New York:  Reinhold, 1963).

88.  Sconce, J. S., Chlorine - Its Manufacture, Properties and
     Uses, American Chemical Society, Monograph Series (New
     York:  Reinhold, 1962).

89.  Selvig, W. A., and F. H. Gibson, Chlorine Determination
     in Coal, Ind. Eng. Chem. 5;189  (1933).

90.  Sextion, A. H., and W. B. Davidson, Fuel and Refractory
     Materials (London:  Blackie and Son, Ltd., 1923).

91.  Shreve, R. W., The Chemical Process Industries, 1st ed.
     (New York:  McGraw-Hill, 1957).

92.  Shreve, R. W., The Chemical Process Industries, 2nd ed.
     (New York:  McGraw-Hill, 1967).

93.  Shriner, D. S., and N. L. Lacasse, Distribution of Chloride
     in Tomato Following Exposure to Hydrogen Chloride Gas,
     Presented at Northeastern Division, American Phytopatho-
     logical Society (Nov. 7-8, 1968).

94.  Smith, W. S., Atmospheric Emissions from Fuel Oil Combustion,
     U. S. Public Health Service (1962).

-------
                                                              50
 95.  Smith, W. S.,  and C. W. Grueber, Atmospheric Emissions
      from Coal Combustion	An Inventory Guide, U. S. Public
      Health Service, Cincinnati, Ohio (1966).

 96.  Snell, F. D.,  and C. T. Snell, Dictionary of Commercial
      Chemicals, 3rd ed. (New York: Van Nostrand, 1962).

 97.  Spector, W. S.  (Ed.), Handbook of Toxicology, vol. 1
      (Philadelphia:  Saunders, 1956).

 98.  Spranger, J. W.,  and A. Peschko, U. S. Patent 2558011
      (1951).

 99.  Standard Methods for the Examination of Water and Waste-
      Water , llth ed. (New York:  American Public Health Associa-
      tion, 1960).

100.  Standard Methods of Test for Ammonia in Industrial Water
      and Industrial Waste Water, ASTM Designation D1426-58,
      American Society for Testing Materials, Philadelphia,
      Pa. (1958).

101.  Standen, A. (Ed. ). "Manganese and Manganese Compounds ",in
      Kirk-Othmer. Encyclopedia of Chemical Technology, 2nd ed.
      (New York:  Interscience, 1967).

102.  Stayzhkin, V.  M. ,  Hygienic Determination of Limits of
      Allowable Concentrations of Chlorine and Hydrochloride
      Gases Simultaneously Present in Atmospheric Air, Translated
      by B. S. Levine,  U.S.S.R. Literature on Air Pollution
      and Related Occupational Diseases 9:55 (1962).

103.  Steere, N. V.  (Ed.), CRC Handbook of Laboratory Safety
      (Cleveland:  The Chemical Rubber Co., p. 498, 1967).

104.  Stern, A. C. (Ed.),  Air Pollution, I, 2nd ed. (New York:
      Academic Press, p. 419, 1968).

105.  Stern, A. C. (Ed.),  Air Pollution, II, 2nd ed. (New York:
      Academic Press, pp.  101, 325, 1968).

106.  Stern, A. C. (Ed.),  Air Pollution, III, 2nd ed. (New
      York:  Academic Press, pp. 192-197, 1968).

107.  Thomas, M. D., Gas Damage to Plants, Ann. Rev. Plant
      Phvsiol. 2:293 (1951).

108.  Thomas Register of American Manufacturers (New York:
      Thomas Publishing  Co., 1968).

-------
                                                              51
109.  Thomas, W. H.,  Science of Petroleum, II (London:  Oxford
      Press, pp. 1053-1056, 1938).

110.  Thompson, Dr. R. J.,  Acting Chief, Laboratory Services
      Section, Division of Air Quality and Emission Data,
      National Air Pollution Control Administration, Cincinnati,
      Ohio,  personal communication.

111.  Threshold Limit Values for 1967, Adopted at the 29th
      Annual Meeting of the American Conference of Governmental
      Industrial Hygienists, Chicago, 111. (May 1-2, 1967).

112.  Toyama, T., H.  Kondoh, and K. Nakamura, Pulmonary Peak
      Flow Response to Acid Aerosols and Bronchodilator in
      Industrial Workers, Japan. J. Ind. Health (Tokyo) _4(8):15
      (1962).

113.  VDI 2106, Part 2 (February 1963), cited in A. C. Stern (Ed.),
      Air Pollution III (New York:  Academic Press, p. 660, 1968).

114.  Waller, R. E.,  Acid Droplets in Town Air,  Intern. J. Air
      Water Pollution 7:733 (1963).

115.  West, P. W., and H. Coll, Direct Spectrophotometric
      Determination of Small Amounts of Chloride, Anal. Chem.
      28:1834 (1956).

116.  West, P. W., and H. Coll, Spectrophotometric Determination
      of Chloride in Air, Proceedings of the Symposium on Atmo-
      spheric Chemistry of Chlorine and Sulfur Compounds,
      Cincinnati, Ohio. 1957 (1959).

117.  Yeau, J. S., and L. Schnidman, Flue Products of Industrial
      Fuels, Ind. Eng. Chem. 28:999 (1936).

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APPENDIX

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APPENDIX
                                       TABLE  2




             PROPERTIES OF HYDROGEN CHLORIDE  AND HYDROCHLORIC ACID49'76
Properties
Color, odor, normal
state
Boiling point
Melting point
Hygroscopicity
Density
Heat of fusion
Heat of vaporization
Hydrogen Chloride
(HCl)a
Colorless gas, pungent,
irritating odor, fumes
in air
-85°C (-121°F)
-111°C (-168°F)
Very hygroscopic
1.6397 g/1 (0°C, 760 mm)
476-504.5 g-cal/mole
3860_+4 g-cal/mole
Hydrochloric Acid
(HC1, aqua)b
Colorless liquid; sometimes yellowish
due to impurities (iron, arsenic,
chlorine, and organic matter) ; pungent
and irritating odor
Aqueous solution containing 20
HC1: 110°C (230°F)
.24%
27.92% HC1: -42°C (-43.6°F)
37.14% HC1: -74°C (-101.2 F)
Hygroscopic
20.04% HC1: 1.1006 g/1
37.14% HC1: 1.1885 g/1


                                                                            (continued)
                                                                                              Ul

-------
                                TABLE 2 (Continued)

            PROPERTIES OF HYDROGEN CHLORIDE AND HYDROCHLORIC ACID49'76
Properties
   Hydrogen Chloride
        (HCl)a
                                Hydrochloric Acid
                                   (HC1, aqua)b
Reactivity
Non-corrosive when dry.
Reacts rapidly with
organic materials
                      Highly corrosive to moist metals with
                      evolution of hydrogen gas.  Reacts
                      with basic salts (metallic oxides and
                      carbonates)
Solubility in H30)
   (g/lOOg H30)
82
67
63
,3  ( 0°C)
.3  (30°C)
,3  (40°C)
                     59.6 (50°C)
                     56.1 (60°C)
       aAlso called hydrochloric acid, anhydrous.

        Also called muriatic acid.

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APPENDIX
                                       TABLE 3




     SUMMARY OF  REPORTED EFFECTS OF INHALATION OF HYDROGEN CHLORIDE  BY HUMANS
Concentration
( ppm ) *
50-100
10-50
10
1,300-2,000
1,000-1,300
50-100
35
1,000-2,000
10
5
Exposure
Time



Few min
30-60 min
60 min




Effects or Comments
Work is impossible
Work is difficult but possible
Work is undisturbed
Lethal
Dangerous
Intolerable
Irritation of throat after short exposure
Brief exposures are dangerous
Irritation
No organic damage
Reference
45,72
45,72
45,72
52,103
52
35,44,52,87
87
87
113
113
                                                                                              Ul
                                                                           (continued)

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APPENDIX
                                  TABLE 3  (Continued)




     SUMMARY OF REPORTED  EFFECTS OF INHALATION OF HYDROGEN CHLORIDE BY HUMANS
Concentration
( ppm ) *
10
0.067-0.134
0.402
0.134
0.335
0.067-0.134
1-5
Exposure
Time







Effects or Comments
Odor threshold value
Odor threshold value
Concentration for threshold reflex effect
on optical chronaxie
Concentration for threshold reflex effect
on eye sensitivity to light
Concentration for threshold effect on
digito-vascular toxicity
Threshold concentrations of change in the
rhythm and depth of respiratory movement
Odor threshold value
Reference
105
28,29
28,29
28,29
28,29
28,29
45
*1 ppm = 1,470
                             at 25°C.
                                                                                             Ul

-------
APPENDIX




                                       TABLE 4




     SUMMARY OF REPORTED  EFFECTS OF INHALATION OF HYDROGEN CHLORIDE ON ANIMALS
Species
Rabbits
Guinea pigs
Cats
Rabbits
Guinea pigs
Cats
Rabbits
Concentra-
tion (ppm)*
4,300
4,300
3,400
3,400
3,400
1,350
1,350
Exposure
Time
30 min
30 min
90 min
90 min
90 min
90 min
90 min
Effects or Comments
Fatal in some cases, due to
laryngeal spasm, laryngeal
edema, or rapidly developing
pulmonary edema
Fatal in some cases, due to
laryngeal spasm, laryngeal
edema, or rapidly developing
pulmonary edema
Death after 2 to 6 days
Death after 2 to 6 days
Death after 2 to 6 days
Severe irritation, dyspnea,
and clouding of the cornea
Severe irritation, dyspnea,
and clouding of the cornea
Reference
45,69
45,69
45,64
45,64
45,64
45,64
45,64
                                                                           (continued)

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APPENDIX


                                 TABLE 4 (Continued)


     SUMMARY OF  REPORTED EFFECTS OF INHALATION OF HYDROGEN  CHLORIDE ON ANIMALS
Species
Guinea pigs
Rabbits
Guinea pigs
Rabbits
Guinea pigs
Rabbits
Guinea pigs
Concentra-
tion (ppm)*
1,350
670
670
300
300
100-140
100-140
Exposure
Time
90 min
2 hr
2 hr
6 hr
6 hr
6 hr
6 hr
Effects or Comments
Severe irritation, dyspnea,
and clouding of the cornea
Fatal in some cases
Fatal in some cases
Corrosion of the cornea and
upper respiratory irritation
Corrosion of the cornea and
upper respiratory irritation
Only slight corrosion of the
cornea and upper respiratory
irritation
Only slight corrosion of the
cornea and upper respiratory
irritation
Reference
45,64
45,69
45,69
45,64
45,64
45,64
45,64
(continued )
                                                                                              Ul
                                                                                              -J

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APPENDIX


                                 TABLE 4  (Continued)


     SUMMARY  OF  REPORTED EFFECTS OF INHALATION OF  HYDROGEN CHLORIDE ON ANIMALS
Species
Rabbits
Guinea pigs
Pigeons
Monkey
Rabbit
Guinea pig
Concentra-
tion (ppm)*
100
100
100
33
33
33
Exposure
Time
6 hr/day for
50 days
6 hr/day for
50 days
6 hr/day for
50 days
6 hr/day
5 days/week
for 4 weeks
6 hr/day
5 days/week
for 4 weeks
6/hr/day
5 days/week
for 4 weeks
Effects or Comments
Slight unrest and irritation of
the eyes and nose
Slight unrest and irritation of
the eyes and nose
Slight unrest and irritation of
the eyes and nose
No immediate toxic effects and
no pathological changes
No immediate toxic effects and
no pathological changes
No immediate toxic effects and
no pathological changes
Reference
45,82
45,82
45,82
69
69
69
                                                                            (continued)
                                                                                               Ul
                                                                                               oo

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APPENDIX




                                 TABLE 4 (Continued)




     SUMMARY OF  REPORTED EFFECTS OF INHALATION OF HYDROGEN  CHLORIDE ON ANIMALS
Species
Rabbits
Rabbits
Concentra-
tion (ppm)*
60
30
Exposure
Time
5 min
10 min
Effects or Comments
Cessation of ciliary activity
without recovery
Cessation of ciliary activity
without recovery
Reference
21
21
       *1 ppm « 1,470 |-tg/m3  at 25°C.
                                                                                              ui

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APPENDIX




                                       TABLE 5




     SUMMARY OF  REPORTED TOXIC EFFECTS OF HYDROGEN CHLORIDE  EXPOSURE ON PLANTS
Species
Plants
Plants
Sugar beets
Viburnum
seedlings
Beech
Oak
Maple
Birch
Pear
Concentra-
tion (ppm)*
10-50
100-1,000
10
5-20
1,000
1,000
2,000
2,000
2,000
Exposure
Time


Few hr
24 hr
1 hr
1 hr



Effects or Comments
No leaf damage
Leaf damage
Threshold for marking
Leaves rolled at the edges,
withered, shrunk, faded, and
necrotic
Local lesions produced
Local lesions produced
Marginal leaf scorch
Marginal leaf scorch
Marginal leaf scorch
Reference
113
113
107
42
42
42
42
42
42
                                                                           (continued)

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APPENDIX




                                TABLE  5  (Continued)




     SUMMARY OF REPORTED TOXIC EFFECTS OF HYDROGEN CHLORIDE EXPOSURE ON PLANTS
Species
Viburnum
seedlings
Larch
Fir
Spruce
Tomato plants
Liriodendron
tulipifera

Alnus
fl,lutinosa

Prunus
serotina
Concentra-
tion (ppm)*
5-20
5-20
1,000
2,000
5
3
6
6
Exposure
Time
48 hr
48 hr
1 hr
1 hr/day for
80 days
2 hr
4 hr
4 hr
4 hr
Effects or Comments
Plants died
Plants died
Local lesions formed
No apparent injury
Developed interveinal bronzing
followed by necrosis within 72
hours after exposure
Threshold for visible injury
Threshold for visible injury
Threshold for visible injury
Reference
42
42
42
42
93
74
74
74
                                                                          (continued)

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APPENDIX




                                 TABLE  5  (Continued)




     SUMMARY OF REPORTED TOXIC EFFECTS OF  HYDROGEN CHLORIDE EXPOSURE  ON PLANTS
Species
Acer saccharus

Acer
platanoides

Quercus rubus

Pinus strobus

Psaudotsuqa
mantissii
Abies
balsamea

Pinus abies

Pinus niqra

Concentra-
tion (ppm)*
7
7
13
8
10
10
19
18
Exposure
Time
4 hr
4 hr
4 hr
4 hr
4 hr
4 hr
4 hr
4 hr
Effects or Comments
Threshold for visible injury
Threshold for visible injury
No visible injury
Threshold for visible injury
Threshold for visible injury
Threshold for visible damage
Threshold for visible damage
No visible damage
Reference
74
74
74
74
74
74
74
74
                                                                           (continued)
                                                                                               tsj

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APPENDIX




                                 .TABLE 5 (Continued)




     SUMMARY OF  REPORTED TOXIC EFFECTS OF HYDROGEN CHLORIDE EXPOSURE ON PLANTS
Species
Thuja occi-
dentalis

Spruce
seedlings
Concentra-
tion (ppm)*
43
<50
Exposure
Time
4 hr
20 min
Effects or Comments
No visible damage
Plants died
Reference
74
61
        *1  ppm = 1,470 |ag/m3  at 25°C.
                                                                                              U)

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APPENDIX
                           TABLE 6

      EMISSIONS OF HYDROCHLORIC ACID  IN SELECTED AREAS
                 OF NIAGARA COUNTY, N.Y.3
                                           HC1  Emitted
       Community	(tons/year)

       Cities:
          Lockport                               187
          Niagara Falls                       3,436
          North Tonawanda                        149

       Towns:
          Cambria                                  5
          Hartland                                 5
          Lewiston                               191
          Lockport                                 9
          Newfane                                 16
          Niagara                                 11
          Pendleton                                4
          Porter                                  10
          Royalton                                 7
          Somerset                                 3
          Wheatfield                             24
          Wilson                                   6

       Villages:
          Barker                                   3
          Lewiston                                 3
          Middleport                              8
          Wilson                                   3
          Youngstown                              3

              Total                            4,083

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APPENDIX
                                            TABLE 7




               HYDROCHLORIC ACID PRODUCTION IN THE UNITED STATES,  1958-196723
Hydrochloric
Acid*
Total HC1
Year (short tons)
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
826,
955,
970,
910,
1,052,
1,053,
1,236,
1,370,
1,519,
1,597,
022
914
167
967
116
502
824
092
372
682
i
i (short
107,
100,
90,
87,
105,
128,
136,
138,
139,
(preliminary) 137,
Process
Salt- Ac id
tons) (percent)
036
008
461
073
830
652
051
121
778
515
13.0
10.4
9.3
9.5
10.1
12.2
10.0
10.1
9.2
8.6
Synthesis
(short tons) (percent)
162,
165,
148,
118,
92,
92,
95,
99,
108,
114,
282
751
304
059
117
276
606
043
028
003
19.6
17.3
15.3
13.0
8.8
8.8
7.7
7.2
7.1
7.1
By-Product
and Others
(short tons) (percent )
556,
690,
731,
705,
854,
832,
1,005,
1,132,
1,271,
1,346,
704
155
402
835
169
574
167
928
566
164
67.4
72.3
75.4
77.5
81.8
79.0
82.3
82.7
83.7
84.3
     * Includes anhydrous  hydrogen chloride.
                                                                                                  en

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                                                              66
APPENDIX
                            TABLE 8




   PRODUCTION OF HYDROCHLORIC ACID BY PROCESS AND STATE88
State
Massachusetts
New Hampshire
New Jersey
New York
Pennsylvania
Alabama
Delaware
Georgia
Kentucky
Louisiana
Maryland
Tennessee
Texas
Virginia
West Virginia
Illinois
Indiana
Kansas
Michigan
Missouri
Ohio
California
Nevada
New Mexico
Washington
Total
Number
Salt-
Acid
1

3



1

1
2


1
1

1
1



2


1

15
of Plants
Direct
Synthesis

1

3



1
3
2


3
1



1
2

1
2


2
22
Using Each
By-
Product
1

7
5
1
2

2
3
3
1
1
8

6
2
2

6
1
4
3
1

1
60
Process
Total
2
1
10
6*
1
2
1
3
5*
5*
1
1
11*
2
6
3
3
1
7*
1
6*
5
1
1
3
88*
        *Some plants use more than one process,

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                                                             67
APPENDIX
                           TABLE 9

    MAJOR PRODUCERS OF HYDROCHLORIC ACID (MURIATIC ACID)
                    IN THE UNITED STATES
                                        108
Company
        Location
Allen, L. B., Co., Inc.
Allied Chemical Corp.,
  Industrial Chemicals Div.
American Cyanamid Co.,
  Industrial Chemicals Div.
American Oil & Supply Co.
Baker, J. T., Chemical Co.
Bay Chemical Co.
Berg Chemical Co., Inc.
Big Ben Chemicals & Solvents, Inc,
Calcine Chemical Co.
Celanese Corp. of America,
  Chemical Div.
Central Chemical Div.
Diamond Alkali Co.
Dover Chemical Corp.
Dow Chemical Co.
Dowell Div.
Essex Chemical Corp.
General Aniline & Film Corp.
Globe Chemical Co., Inc.
Haviland Products Co.
Hooker Chemical Corp.
  Industrial Chemicals Div.
Hubbard-Hall Chemical Co.
International Minerals &
  Chemical Corp.
International Minerals &
  Chemical Corp.
Johnson Mfg. Co.
Jones Chemicals, Inc.
Knight, Maurice A., Co.
Kraft Chemical Co.
McKesson & Robbins, Inc.,
  Chemical Dept.
Mercury Chemical Corp.
Monarch Chemical Works, Inc.
Monsanto Inorganic Chemicals Div.
National Zinc Co., Inc.
Neville Chemical Co.
Nitine Inc.
Octagon Process Inc.
Schiller Park, 111.

Morristown, N.J.

Wayne,  N.J.
Newark,  N.J.
North Phillipsburg, N.J.
Chicago, 111.
New York, N.Y.
Chicago, 111.
Jersey City, N.J.

New York, N.Y.
Calumet City, 111.
Cleveland,  Ohio
Dover,  Ohio
Midland, Mich.
Tulsa,  Okla.
Clifton, N.J.
New York, N.Y.
Cincinnati, Ohio
Grand Rapids, Mich.

Niagara Falls, N.Y.
Waterbury,  Conn.

Skokie,  111.

Chicago, 111.
Princeton,  Iowa
Caledonia,  N.Y.
Akron,  Ohio
Chicago, 111.

New York, N.Y.
Metuchen, N.J.
Omaha,  Nebr.
St. Louis,  Mo.
New York, N.Y.
Pittsburgh, Pa.
Whippany, N.J.
Edgewater,  N.J.
                                                  (continued)

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                                                             68
APPENDIX
                     TABLE 9  (Continued)

    MAJOR PRODUCERS OF HYDROCHLORIC ACID (MURIATIC ACID)
                    IN THE UNITED STATES108
Company
        Location
Olin Mathieson Chemical Corp.
Pennsalt Chemical Corp.
Phillipp Brothers Chemicals Inc.
Potash Co. of America
PPG Industries Chemical Div.
Riverside Chemical Co., Inc.
Robinson Bros. Chemicals  Inc.
Rohm & Haas Co.
Seaway Chemical  Corp.
Siegel Chemical  Co., Inc.
Solvent Chemical Co.
Smith-Douglass Co., Inc.
Stauffer Chemical Co.
  Industrial Chemical  Div.
Tenneco Chemicals Inc.
Triple-X Chemical Laboratories,
  Inc.
United States Rubber Co.,
  Chemical Div.
Velsicol Chemical Corp.,
  Tennsyn Div.
Vulcan Materials Co.,
  Chemicals Div.
Wittichen Chemical Co.
New York, N.Y.
Tulsa, Okla.
New York, N.Y.
Carlsbad, N. Mex.
Pittsburgh, Pa.
North Tonawanda, N.Y,
Brooklyn, N.Y.
Philadelphia, Pa.
Buffalo, N.Y.
Brooklyn, N.Y.
Maiden, Mass.
Norfolk, Va.

New York, N.Y.
New York, N.Y.

Chicago, 111.

Naugatuck, Conn.

Chattanooga, Tenn.

Wichita, Kans.
Birmingham, Ala.

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                                                           69

APPENDIX




                         TABLE 10


    CONSUMPTION OF HYDROCHLORIC ACID BY USES, 196358
Uses Approximate %
Organic chemicals
Inorganic chemicals
Metal production
Metal and industrial cleaning
Food processing
Oil well acidizing
Total
49
5
17
7
4
18
100
100% HC1
(Short Tons)*
516,500
52,600
179,000
73,700
42,200
189,500
1,053,500
       *Approximately calculated  on basis  of  1963 total pro-
 duction  of  1,053,502 short  tons  (see  Table 7, Appendix).

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                                                             70
 APPENDIX
                           TABLE 11

             CONSUMPTION OF HYDROCHLORIC ACID BY
            SELECTED INDUSTRIES, 1963 and 1958
Industry
Organic chemicals3
Intermediate coal tar products
Inorganic chemicals9-'*3
Alkalies and chlorine
Plastics material and resins
Total
100% HC1
1963
438,746
79,505
51,200
44,557
13,993
628,001
(Short Tons)
1958
280,822
18,802
24,400
12,280
36,754
373,058
       aNot elsewhere classified.

       ^Estimated from total money spent in 1958 and 1963 by
inorganic chemical industries and prices paid during those
periods by other industries.

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APPENDIX                                                    71
                         TABLE  12




   CHLORINE CONTENT OF  SELECTED UNITED  STATES  COALS95
Source of
State
Ohio
Illinois
Indiana
West Virginia
Pennsylvania
Illinois
Oklahoma
Coal
Bed
Sharon
No. 6
No. 4
Pittsburgh
Lower Freeport
Central Illinois
Henryetta
Chlorine Content
(percent)
0.01
0.01
0.06
0.07
0.14
0.35
0.46

-------