AIR POLLUTION CONTROL
TECHNICAL REPORT
ODOR CONTROL INVESTIGATIONS
.
B. N. Murthy and B, C, Eusebio
DCS/RLB - 71-2
March 1, 1971
^
U. S. ENVIRONMENTAL PROTECTION AGENCY
Air Pollution Control Office
Division of Control Systems
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ANNUAL RESORT
Jan. - Dec. 1970
ODOR CONTROL INVESTIGATIONS
B. N. Murthy and B, C, Eusebio
DCS/RLE - 71-2
March 1, 1971
Research Laboratory Branch
Division of Control Systems
Cincinnati, Ohio
ENVIRONMENTAL PROTECTION AGENCY
Air Pollution Control Office
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SUMMARY
The odor control investigations in the Control Device Development Section
include both in-house and contract-support research work for the develop-
ment of suitable devices & processes for control of odorous emissions from
stationary sources. DPCE started the investigations in 1968 with a lit-
erature survey on the state of the art of odor control technology, which
resulted in a report including recommendations for research and develop-
ment to be supported by DPCE.
The in-house work during 1970 consisted of laboratory studies aimed at
development of suitable wet-scrubbing reagents for odorous compounds
representing emissions from stationary sources. Two compounds in each
of three groups of odorous emissions (mereaptans, amines and aldehydes)
were treated separately with several of the possible aqueous scrubbing
reagents under identical conditions, for comparison of the reagent
capabilities for absorption of odors from air. The tests enabled the
identification of specific reagents having the maximum scrubbing
efficiency for each odorant species. Detailed kinetic studies to deter-
mine the optimum operating conditions and design data for scrubbers
have been planned.
A contract project for studies on the adsorption of odorants on activated
charcoal was started during the year at Kansas State University. The
studies are aimed at determining equilibrium adsorption conditions and
deriving mathematical models useful for the design of large scale ad-
sorption control devices for odor control. Literature survey and ap-
paratus construction were in progress at the end of 1970.
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INTRODUCTION
DPCE started the odor control investigations in 1968, with a liter-
ature survey on the state of the art of odor control technology. The
survey resulted in a. report which included recommendations for research
on odor control to be supported by DPCE (Appendix A),
Based on the recommendations, the in-house odor control project aimed
at development of suitable wet scrubbing was started in late 1969. Odorous
compounds representing those present in the emissions of the most object-
ionable stationary industrial sources were selected for the studies. A
laboratory study was planned to determine in the in-house laboratories,
the most promising set of reagents which could economically absorb
and remove odors in wet scrubbers.
Besides wet scrubbers, the control devices which were identified as
requiring detailed investigations for improvement and adaption to
odor control were:
adsorption units
catalytic converters
afterburners
combinations of control devices
A contract for Fundamental studies on the adsorption of odorants on
activated charcoal was signed with Kansas State University.
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DISCUSSION
In-house screening tests.
An experimental bench-scale apparatus including gas purifiers, metering
devices, temperature controls, absorption section and sampling ports,
was constructed. A schematic design of the screening test system is
shown in Fig. 1. The entire test system was set-up inside a large fume
hood to prevent odor pollution episodes in the laboratory. An adsorption
filter was installed in the fume discharge duct which removed odors
from the fume hood.
The following odorants were selected for studies on the comparative
efficiencies of their removal from air by adsorption in several reagents:
Odorants Common Industrial Sources
Organic sulfur compounds- Paper and pulp , agricultural chemicals ?
butyl and methyl mercaptans plasticizers , rubber products
Nitrogeneous compounds Fish processing industries, rendering
- mono, di and tri methyl plants
Aldehydes Rendering plants, Incinerators
Butraldehyde plastics
Propionaldehyde
Iso-valeraldehyde
From a knowledge of the chemistry of the odorants, and from the literature
survey, the following reagents were selected for experimental studies on
odor adsorption:
a) alkalis
- sodium hydroxide
- calcium hydroxide
- sodium carbonate
b) acids
- hydrochloric
- sulfuric
- sulfamic
c) oxidizing agents
- potassium permanganate
- sodium and calcium hypochlorices
d) other reactants
- bisulfites
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The inlet concentration of each odorant in the air stream was held
constant at 5000 ppm. The reagents were compared at concentrations
ranging from 0.5 to 5 percent in water.
Analysis of the odorant before and after treatment with the reagent
was by gas chromatography- Suitable combinations of column type,
temperature, and detector were developed for the analysis of each
odorant. The reagents were analyzed by standard wet chemical methods.
The complete results of the screening tests will be reported in a
paper being prepared for publication. Some typical results are shown
in Figs. 2, 3, and 4. The following main observations have been made
from the screening test results:
* Amines are efficiently removed by hydrochloric or sulfuric acid.
* Sodium hydroxide is the best scrubbing reagent for mercaptans,
while calcium hydroxide slurry is a promising scrubber from the
economic aspect.
* Aldehydes are scrubbed best by sodium and calcium bisulfites.
* Potassium permanganate is a uniform scrubber for all the odorants,
but is not the most efficient for any odorant. (Efficiency of odor
removal was defined as percent of inlet odor absorbed by the same
volume of reagent under identical conditions ,of contact time
and reagent concentration.)
* The efficiency of potassium permanganate depends oil the pH of the
solution, and is maximum in the pS range of 8 to 10.
The effect of operating conditions on the rate of odorant removal will
be studied in detail with the best reagents for each type of odorant.
Mathematical models useful for the design of wet scrubbers for odor
control will be derived from the kinetic studies.
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Program Plans
A proposed 5-year program plan for odor control projects to be conducted
in-house and by contract was prepared.
The in-house projects identified will include:
a) Kinetic studies for odor control
b) Pilot scale wet-scrubber development studies
c) Semi-pilot scale adsorption studies for odor control
d) Catalysis and afterburner development
e) Development of combined two-stage control devices and optimization
studies
f) Design and development work for odor control demonstration
Contract projects identified were:
a) Odor adsorption studies using activated charcoal
h) Selective sorption device development
c) Odor control devices system study
d) Follow-up R & D studies from odors control and related system studies
e) Economic analysis and development of prototype odor control programs
f) Demonstration studies
Procurement plan for the system study project to be supported on contract
is being prepared and a strong recommendation to fund the study during
FY72 will be made,
Existing Contract Activity
The in-house literature survey on the state of the art of odor control
had revealed the need for developmental work on adsorption control
devices as a high priority project.
A project was initiated with the contract signed with Kansas State
University for conducting fundamental studies relating to equilibrium
conditions and kinetics of adsorption of odorants in dilute concentrations
appearing in the emissions of stationary sources. The detailed work plan
is attacked as Appendix B. '
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Literature survey, experimental apparatus construction, arid calibration
are in progress. The contract will be completed in September, 1972-
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CONCLUSIONS
The state of the art survey on odor control has pointed out the urgent
need for research and development work in the following areas:
* Wet scrubber development
* Adsorption
* Afterburners and catalysis
* System study on odor control devices
* Optimization and engineering economic studies of combined two
stage systems
In-house screening tests have shown that the following combinations
of odorant-reagent require detailed investigations for wet-scrubber
development:
Mercaptans - Sodium and calcium hydroxide
Aldehydes - Sodium and calcium bisulfites
Amines - Hydrochloric and sulfuric acids
All odorants - Potassium permanganate
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RECOMMENDATIONS
1. Follow-up work to the screening tests should be conducted in-house.
Kinetic studies for odor control by gas-liquid contacting should be
initiated to develop mathematical models correlating operating
variables with rate of reaction. Mass-transfer effects in the exper-
imental system should be kept at the least rate-limiting level to
enable the determination of chemical reaction steps.
The follow-up studies on wet-scrubber development will use the
results of the kinetic studies for developing optimum scrubber designs
for efficient and economic odor control systems.
2. Semi-pilot and pilot scale studies on adsorption and regeneration
should be conducted to determine the effect of fluid dynamic conditions
on power requirements and material costs.
The mathematical models developed from fundamental laboratory studies
should be used in the design of pilot scale fixed and fluidized bed
absorbers.
3. Though activated charcoal is widely used as an adsorbent for odor
control, it is a poor adsorbent for some odorants. Selective adsorbents,
either through modification of activated charcoal or by investigation of
other surface active materials, should be developed for efficient odor
control in specific cases. Examples of odorants not effectively con-
trolled by activated charcoal are:
Hydrogen sulfide
Carbonyl sulfide
Acetaldehyde
Amines
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4. A system study on the present application of odor control devices
and their limitations is needed to define the problems with existing
control devices, and to identify research and development needs for
eifective odor control. The potential of existing control technology
for odor control applications should be investigated.
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Purge
Purified Air
Mixer I
Mixer II
Test Scrubber
G. L, C.
Fig 1
SCREENING TESTS - SCHEMATIC DESIGN OF TEST SCRUBBER - BENCH SCALE
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mlt 3-10-70
0.5 % KMn04
ph 10
8
10
12
14
Time (min.)
Fig. 2
BUTYL MERCAPTAN SCREENING TESTS
16
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MLT 2-5-70
Time (min.)
Fig. 3
DIMETHYLAMINE SCREENING TESTS
L_ L
5
10
15
20
25
30
35
40
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mlt 5-19-70
100
5% Ca(HS03)2
2% KMn04 ph 10
w/ TCP
5% KMn04 ph 10
w/ TCP
1% KMn04 ph 10
w/ TCP
1% KMn04 ph 10
w/ TCP
Borax 5%
CaOCl2l% & 5%
Ca(OH| 1% & 5%
Dem. Dist. H 0
HC1 1% & 5%
5%
H2S04 1% & 5%
NaOCl 1%
NaOH 1% & 5%
Na2C03 1% & 5%
Sulfamic Acid 5%
Time (min.)
6 8 1Q
BUTYRALDEHYDE SCREENING TESTS
16
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APPENDIX A
ODOR CONTROL RESEARCH
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A State-Of-The-Art Report and Research Recommendations
ODOR CONTROL RESEARCH
March, 1969
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SUMMARY
This report is a review of the state of technology for odor control and
evaluation. The emission of odorous compounds forms a significant
portion of the air pollution problem. It has been established that ob-
jectionable odors produce nausea, disturb sleep, and reduce property
value.
Odor surveys indicate that the most common odor emission sources
are chemical and pulp manufacturers, petroleum and mineral refin-
eries, and food stuff waste product and animal rendering industries.
The technology of odor evaluation and control has not advanced to keep
pace with the growing problem. No suitable method or instrument is
available for measuring odors objectively. Odor measurement tech-
niques presently being used are mainly subjective. Consequently, there
is a marked deficiency of quantitative information on odor emissions
from industrial sources.
Techniques that can be used for odor control are ventilation, absorption
chemical reaction, process changes, odor modification, combustion,
and scrubbing. Of these, scrubbing offers the advantage of not being
highly specific to particular odorous emissions.
Research needs for the development of scrubbers to control odors are
discussed in this summary report. The report recommends that simple
odorous systems amenable to accurate analysis be selected initially.
Gas chromatographic equipment will be used for analysis of odorants.
The effect of operating variables on the efficiency of odor control will
be studied on a bench scale. Results from these studies will be used
to form the input for pilot-scale scrubber studies.
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INTRODUCTION
One of the major uncontrolled air pollution problems is the emission of
odorous compounds into the atmosphere as a result of industrial activity.
Although gross atmospheric pollution in the form of smoke and dust has
been subjected to appraisal, regulation, and statutary restriction, at-
tempts to control odors have been highly complicated as a result of the
lack of uniform standards for measurement and classification of odors.
The magnitude of the overall odor pollution problem, as indicated by
the number of complaints about odors in ambient air surrounding indus-
tries, is increasing.
Odor is defined as the characteristic of a substance that stimulates the
sense of smell, either pleasantly or unpleasantly. The substance is
usually airborne. V/hen a solid or liquid gives out an odor, the stimulus
is caused by the volatile molecules from the substance reaching the
sensory nerves in the nose.
The relationship between the physical and chemical property of a sub-
stance and its odor quality has not been definitely established. Our
understanding of the sense of smell is considerably less advanced than
our understanding of .other senses. Attempts to classify odors accord-
ing to molecular structure have not been very successful. For instance,
aldehydes, carbonyls, sulfur compounds, and hydroxy compounds cause
certain typical smells, but take on entirely different characteristics at
various concentrations in air. The odor of a mixture of odorous com-
pounds cannot be predicted from a knowledge of their individual odors.
The problem of classifying odors in terms of basic types is further com-
plicated by psychological and physiological factors. An odor that is of-
fensive to one person may be tolerable or even pleasant to another.
But some smells fall definitely into the class of offensive odors. These
include the putrefractive and fecal odors and some chemical odors that
are generally considered objectionable.
Until recently, odors were considered something inevitably present
around industrial areas and few attempts were made to control them.
It has now been established that objectionable odors produce nausea,
disturb sleep, and reduce property value. Some odors, like emissions
from acrylate industries, are toxic even at low concentrations. 3 Al-
though ail industrial odors are not inherently harmful by nature, some
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authorities believe that many odors may adversely affect public health^
by causing an ionic imbalance in the atmosphere. The presence of ex-
cessive positive ions in air irritates mucous membranes, interferes
with ciliary activity, and may increase general susceptibility to viral
infection.'*
Since industrial odors are a definite part of the overall air pollution
problem, people concerned with the design, supervision, or administra-
tion of chemical plants should be familiar with the latest techniques avail-
able'for controlling odors. The purpose of this report is to review the
state-of-the-art regarding odor evaluation and control methods and to
make recommendations for a plan of research that will lead to the devel-
opment of effective odor control techniques.
SOURCE OF ODOR
Before an effective odor control program can be launched, the sources
and nature of odorous emissions must be identified. At present, there
is a marked deficiency of published literature on the quantities, types,
and concentrations of odorous emissions.
In 1955 an opinion survey was conducted by Pendray and Company in
67 major industrial cities. 5 Members of the communities v/ere ques-
tioned about the sources of odors. This survey resulted in an estimate
of the qualitative nature of the problem, and indicated that the most
common sources of odors were the chemical manufacturers (Appendix A).
More recently, in 196S the U.S. Public Health Service conducted an odor
survey in the St. Louis communities bordering Missouri and Illinois.
This survey again was a qualitative assessment of the frequency and ob-
jectionability of odors as sensed in ambient air by volunteers geograph-
ically distributed over the area. The survey showed that 80 percent of
the chemical odors and 98 percent of the animal odors (from rendering
plants and stockyards) were considered to be objectionable (Table 1).
The magnitude of the odor problem and an estimate of the quantity of
odorants to be removed at their source can be determined by the ob-
jactionability, odor threshold, and physiological effects of odors at
ambient concentrations. An objectionability scale ranging from "like
extremely" to "dislike extremely" has been proposed by Turk^ to
determine subjective reactions to odors., Objectionability alone cannot
be a sufficient criterion for control. For example, hydrogen sulfide at
concentrations sufficient to produce harmful effects loses its character-
istic offensive odor and produces a pleasant smell. The characteristic
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smells and odor thresholds for some of the commonly occurring pol-
lutants are given in Table 2.4 The odor threshold for an odorous sub-
stance in the atmosphere is the minimum concentration that can be
detected by the human sense of smell.
In this review the common sources and compositions of odorous emis-
sions have been compiled from the literature and are listed in Appendix
B. To assess the relatrve contributions of the sources of air pollution,
the major types and quantities of pollutants emitted have to be classified.
The U.S. Public Health Service has published a compilation of air pol-
lutant emission factors,8 along with quantitative estimates of a few
odorous emissions. An emission factor is defined as the statistical
average of the rate at which pollutants are emitted from the processing
of a given quantity of raw material. We may conclude from the study
of emission factors that the major chemical source contributing to the
odor problem is the pulp and paper industry. The characteristic odor
from a pulp mill results mainly from a group of organic sulfur com-
pounds of which the most important are methyl rnercaptan and its oxi-
dation products, dimethyl sulfide and dimethyl disulfide. 10
A survey of the odor complaints received by the Intercommunity Air
Pollution Control Program of the city of Cincinnati indicated that most
of the complaints were about odors from rendering plants, asphalt proc-
essing, and plastics industries. No quantitative information on these
sources is available, however.
As part of its contract program, the Division of Economic Effects Re-
search of the National Air Pollution Control Administration is conduct-
ing a study of the odor problem in the nation in terms of sources,
description of odorants (character, acceptability, and other measures),
population- affected, and geographic distribution. ^ The study is aimed
primarily at the promulgation of air quality criteria. Phase I of the
study is expected to identify the industrial processes and other sources
and describe major odorants. Phase n includes an estimation of the
socio-economic impact of odors on the community. There is a great
need for quantifying the type of data expected to be obtained in the study
mentioned above, so that the results can be used to develop control
techniques.
ODOR MEASUREMENT
The most effective odor control methods are those that prevent the re-
lease of odorous pollutants into the atmosphere. Accurate assessment
of the odor problem and control equipment performance requires adequate
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techniques for measuring odors over a wide range of concentrations. At
this time, however, there are no fully satisfactory techniques for deter-
mining the character and intensity of an odor. This defficiency is undoubt
edly due in part to the lack of a satisfactory theory or even a-working
hypothesis covering the physiology, psychology, physics, chemistry,
and other aspects of the sense of smell.4
v,
Measurement of Character and Intensity of Odors
Some attempts have been made in the past to characterize odors in terms
of basic odor qualities. The number of suggested basic odor types varies
from four upwards. Crocker and Henderson*2 have used (1) fragrant,
(2) sour (acid), (3) burnt, and (4) goaty (caprylic). The object of this
kind of classification is to simulate an odor by mixing the basic types.
Henning1^ has suggested six basic types: (1) spicy, (2) flowery, (3)
fruity, (4) balsamic (resinous), (5) burnt (empyreumatic), and (6)foul
(offensive). Zwaardemaker- and others have suggested from six to
eighteen basic odor types. For practical use in the development of con-
trol technology, none of these classifications has been generally accept-
able.
Most industrial odors are complicated mixtures of several chemical
components. Since instruments have not been perfected to analyze odors
objectively, subjective evaluation by human observers is often used to
estimate the character and intensity of industrial odors. There are
mainly two methods by which the subjective (or sensory) evaluation is
practiced: (1) dilution and (2) suprathreshold or matching standard. *
In both methods the intensity of an odor is measured in terms of 'odor
units'. An odor unit is defined as the amount of odor necessary to con-
taminate 1 cubic foot of clean odor-free air to the threshold level.13:14,15
The number of times a given volume of the sample gas has to be diluted
with clean odorless air to bring it to the threshold level (detected by 50
percent of a panel of observers) is the value of the intensity in odor units.
The product flow rate times the odor intensity gives the rate of odor
emission.
Dilution Methods
Four major techniques are used to apply the "dilution" method of meas-
uring odor intensity in terms of odor units:
1. Cdorant air mixture with odor-free air in a container is brought
to an opening and sniffed.
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2. Part or all of the diluted mixture in a container is injected into
the nose.
3. The diluted mixture is ducted into a hood or chamber enclosing
the observer or only his face.
4. Odor-free and odorous air are inhaled in controlled proportions.
Of these methods, those in which the nose is immersed in the diluted
mixture give more accurate results than the injection or inhalation
method, because in the immersion method the dilution rates and the rate
of odor delivery are exactly controlled by an unbiased operator. In the
injection method the panel member himself controls the rate of release,
the rate of injection, and the amount of inhalation. Also, it is impossible
to measure dilution by air that is displaced by the sample injected into
the nose.
Several devices for diluting gases for odor measurement have been de-
" C 9 v 99
scribed in literature. i°~<" Among these, the ASTTvI syringe technique-^
is widely used to measure the strength of odors at effluent sources for
rough evaluations of the performance of control devices. The method
consists of drawing the odorous gas into a graduated I00-ml syringe,
sampling it into a 2-ml syringe, and diluting it with odor-free air in
another 100-ml syringe. A special sampling and diluting device is con-
structed for the method from standard hypodermic needles, which fit the
syringes. The method is simple and gives rapid approximate measure-
ments of odor intensity.
Matching Standard Methods
For the matching standard method, a set of standards is calibrated to
indicate objectionability and odor intensity on a scale. Odor ants of
known concentrations are prepared as standards. A nine-point scale of
the type shown in Figure 1 was used by Duffee and co-workers1 to rep-
resent both objectionability and intensity.
An advantage of this method is that a concentration above the threshold
level can be directly matched against a standard mixture. The method
is rapid, but not very accurate since the intensity of odor from a com-
plex mixture is easily affected by extraneous factors like impurities
(even in traces), humidity of ambient air, and temperature.
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None Slight Moderate Strong Extreme
I i i i i | I i I
Figure 1
Analytical Methods
For developing or evaluating a control device, the best method of odor
measurement is one that gives absolute concentrations of odorous com-
pounds in emission streams. The analytical methods used for measure-
ment of odorant concentrations are chemical or instrumental. In many
practical situations the composition of the odorous effluent can be deter-
mined from a knowledge of the chemistry of the process or by analysis
of emission samples. The odor intensities of pure compounds have
largely been found to follow the Weber-Fechner equation:1
P = K log S
where P = odor intensity
K = a constant
and S = concentration of the odorant in air
For a mixture of compounds whose odor threshold data are available
through previous determinations, gas chromatographic analysis has been
successfully employed to estimate the odor intensity directly. 20-26 Q^LS
chromatography offers an accurate method for analyzing complex mixtures
over a wide range of concentrations.
-«» *
In some cases, a correlation between the concentration of a particular
constituent and the odorant concentration or odor intensity can be estab-
lished. An example of the application of this approach involves the use
of devices to measure the concentration of carbon monoxide as an index
of the intensity of domestic incinerator effluent odor. 23 This approach
assumes a constant relationship between the components of the effluent
stream.
ODOR CONTROL
The development of devices specifically suitable for odor control has
not received sufficient attention in the past because of the diverse nature
of the problem. The total quantity of gaseous emissions that must be
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handled for the removal of odorants usually is large and results in high
energy consumption and equipment costs. Thus, the choice of a partic-
ular odor control method depends on economic as well as technical con-
siderations.
There are four major ways to control odors;
1. Ventilation and diffusion.
2. Chemical conversion - combustion, chemical reaction, or
change of process.
3. Odorant capture - adsorption and absorption.
4. Masking or counteraction.
^ i
Ventilation and Diffusion
Ventilation is the most common method of removing odorous air from en-
closed spaces. Industrial effluents are often diffused through stacks into
the atmosphere so that the odorous effluent is substantially diluted and
reduced to below the threshold level in the ambient air. This method
cannot be successful if a large quantity of odorant is discharged or if the
quality of the outdoor air is unsatisfactory.
Chemical Conversion
Combustion is the most commonly used method for odor control. This
method of control can be attained by direct incineration or,catalytic oxi-
dation. Direct incineration is usually accomplished by supplementing the
odorous effluent with a fuel such as natural gas to provide incineration
temperatures of 1200 to 1500°F. Odorants can be incinerated at sub-
stantially reduced temperatures (600-900°F) if combustion catalyst is
used. Oxy-cat Company^ ^^ developed catalysts to reduce the inciner-
ation temperature of odorants to less than 600°F. The main advantages
claimed for the catalytic combustion method are low energy requirement
and nearly complete elimination of odors. For both modes of incineration
however, when the concentration of combustible odorant in the effluent
stream is low, the need to heat the large quantity of admixed air and
water vapor to the combustion temperature of the odorant makes incin-
eration economically unattractive.
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A number of processes employed by industries fall in the category of
chemical reaction. Examples include the kraft pulping industry, where
sulfate black liquor is oxidized to prevent the emission of mercaptans
and hydrogen sulfide into the atmosphere. 31,32
Scrubbing may be used to remove odorous pollutants from a gas stream
by condensing or absorbing the pollutants in a liquid. Water is widely
used for this purpose. If an odor ant can be reacted with a liquid to form
soluble compounds or precipitates, chemical reaction accompanying
correlation or adsorption completely removes odors. Examples of
aqueous scrubbing include the work of Borger,36 wno has described
the development of a method for successfully eliminating dimethylamine
odors by scrubbing with water and dilute acid in absorption towers.
Many odorous pollutants can be reacted with aqueous permanganate solu-
tion to eliminate the odors. 33 This method is economically applicable
under conditions where effluents with high moisture contents are to be
treated. Rendering plant odors can largely be controlled by use of scrub-
bing devices.35
Essentially all kinds of scrubbing equipment (spray towers , cyclone
scrubbers, packed beds, venturi, etc.) can work at high efficiencies
when the odorant is absorbed easily. If the reaction or solubility in the
liquid is slow, packed towers or plate towers provide the residence time
needed to achieve the required mass transfer. Designs using free liquid
jet or spray are useful when simultaneous adsorption of odorous compo-
nents and precipitation of solids are required. Packed towers and tanks
are not suitable for this purpose, however, because the solids remain
suspended. In general, pressure drop is high in plate towers and agitated
tanks, moderate in packed towers, and low in spray towers and cyclone
s crubbers.
The'advantage of using scrubbers is that large quantities of odorous ef-
fluent can be handled continuously and economically.
Odorant Capture
Active carbon is widely used to adsorb odorous components from air.
When the carbon is saturated with the odorous component, it is deacti-
vated and must be reactivated. Carbon adsorption is used to control
enclosed atmospheres and to eliminate solvents and vapors from effluents.
Other substances like silica gel and activated alumina are used as ad-
sorbents in some cases. 34
8
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Masking
Odor masking can be employed to cover up non-toxic pollutants. In this
method a pleasant smelling or counteracting reagent is injected into the
odor-contaminated air. The masking agent acts in one or more of the
following ways: (1) overwhelms the odor, (2) modifies the properties of
the odorant to produce a less objectionable odor, or (3) numbs the sense
of smell momentarily so that the odor does not seem offensive. Masking
agents are usually aromatic compounds like benzyl acetate and phenyl-
ethyl alcohol. The advantage of this method is its low capital investment.
Masking generally cannot be recommended where odor ants in large quanti-
ties are emitted.
RESEARCH AND DEVELOPMENT OF ODOR CONTROL
As noted earlier in this paper, odor control problem definition and
quantification, odor measurement, and odor control are largely unde-
veloped technologies. Very little research and development to bridge the
gaps in this air pollution control area are underway. Limited work is
being done to identify and deal with the problems of odor control from
motor vehicles; however, no analogous programs can be identified for
the equally or more important problem of odor control from stationary
sources.
Some odor control research relating to kraft mill effluents has been going
on for more than 10 years under the sponsorship of the Public Health
Service6,37 ancj the British Columbia Research Council. 38 TO a large
extent, research in this field has been oriented to a detailed study of the
reactions that contribute to odor pollution so that processes may be
changed to overcome this problem. The principal control methods de-
veloped'are incineration, alkaline absorption (scrubbing), heat recovery,
black liquor oxidation, and chlorine treatment. The problem of krafc
mill odors has not been completely solved; further research on basic
changes in both the pulping and recovery stages would aid in overcoming
the odor problem.
Research and development is urgently needed to control chemical and
rendering plant odors, since the methods now being employed are in-
adequate. The large number of complaints received in surveys on odor
problems attest to this need. ^
A well-supported research program extending over the next 5 to 10 years
will be required to develop technology for control of odor pollution to a
level comparable to ihose for control of particulate and many gaseous
colluiants.
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RECOMMENDATIONS FOR DPCE RESEARCH AND
DEVELOPMENT ON ODOR CONTROL
A. Simple odorous gases and vapors that are known to be present as
objectionable effluents from industries should be selected for control
research. Examples of pure compounds that have been identified in
complaints include
Acrylates (
Acrolein < Plastic industries
Acrylonitirile (
Methyl mercaptan(.
Dimethyl sulfide < Pulp mills, rendering plants
Dimethyl disulfide (^
1,5 diaminopentane (cadaverine) - Rendering
plants
The Manufacturing Chemists Association has very recently published
their latest findings on odor threshold research on 53 odorous com-
mercial compounds (Appendix C). This information should provide a
basis for evaluating odorant removal efficiency.
B. Selected odorant compounds should be analyzed directly by instru-
mental methods. A gas chromatographic analyzer appears to be most
suitable for accurately analyzing mixtures of odorant compounds over a
wide range of concentrations (pure compound to < 0.5 ppm).
C. A screening study of scrubber reactants for controlling odorant
compounds should be conducted:
1. The effectiveness of various scubbing liquids or catalysts in
removing odorants from gas streams should be determined in
bench-scale screening tests. Gas bubblers and liquid-gas re-
action vessels should be employed.
2. Rates of reaction or absorption under variable conditions of
composition of scrubbing reagent, pH of the liquid, temperature,
and inlet gas concentration should be suited.
10
-------
3. Results of the screening test should be used in the selection of
a scrubber system for further research.
D. A preliminary pilot- or bench-scale odor control process design
should be developed. The economics of the process should be evaluated.
E. Different types of scrubbers should be evaluated for their efficiency
in separation of odorants from effluent streams.
1. The design features of the scrubber unit should be developed
from studies of the effect of operating conditions on efficiency
of odor control.
2, Scrubbers as gas-liquid chemical reactors should be evaluated
on a pilot scale.
3. Economically advantageous related phenomena like condensation
should be incorporated in scrubber designs.
F. Fundamental principles and relationships that guide the improve-
ment of scrubber systems as control devices should be investigated. For
example, combined adsorption of odorants.on solid particles and removal
in scrubbers may lead to the development of systems that would remove
particulate and gaseous pollutants in a single unit.
A proposed work schedule for the above program is attached as
Appendix D.
11
-------
Table 1
ST. LOUIS SURVEY: FREQUENCY
OBJECTIONABILITY OF ODOR TYPES6
Odor Type
Chemical
Food
Combustion
General industrial
Animal
Combustion waste
Decomposition
Vegetation
Miscellaneous
No description
% Frequency
17.8
2.7
30.7
5.3
4.4
22.8
4.3
2.5
3.7
6.3
Averages
% Objectionability^
80.9
12.1
65.3
62.0
98.-0
50.6
83.2
8.7
51.7
60.7
% frequency = positive observations -rtotal positive observations, %.
% objectionability = unpleasant observations -i-positive observations, %.
12
-------
Pollutant
Vanillin
Skatole
Musk, synthetic
Ethyl Scleno
mercaptan
Ethyl mercaptan
Allyl mercaptan
Ethyl selenite
Propyl mercaptan
Allyl disulfide
Hydrogen sulfide
Ethyl sulfide
Butyric acid
Idodoform
Valeric acid
Methyl mercaptan
Apiolc
Chlorine
Pyridine
Formula
CH3OCgH3(O?I)CHO-
CgH4-C(CH3)-CH-NH
C-CEL-CH,-CHQ-C
o <5 o
C0H,-SeH
/ 5
CH2-CH-CH -SH
C9H,-Se-C9H,
2, 5 25
CH9-CH-
£1
H.S
CH-
CH3-CH2'CH2'COOH
CHI3
(CHJ9-CH-CHo'COOH
O & £*
CH3O-CH2-CH-CH2CH3O-O-CH2'O
C19
£j
C5H5'N'
Odor
Sweet, aromatic
Fecal
Musk
Foul, foetid
Decayed cabbage
Garlic
Putrid, nauseating
Unpleasant
Garlic
Rotten eggs
Foul, garlic
Rancid, perspiration
Antis eptic
Unclean body odor
Decayed cabbage
Parsley
Pungent
Empyreumatic
Odor Threshold,
ppm
32.10'
75
42.10
18.10
_Q
-8
-7
16.10
5.10
62.10
75
1.10
11
25.10
28
37
62
11.10
63
1.10
12.10
-6
-5
-6
-5
-4
-2
-3
-------
Table 2. Cont'd
Pollutant
Formula
Odor
Odor Threshold,
Dimethyl sulfide
Diacetyl
Ammonia
Ozone
Hydrogen selenide
Phenol
Dimethylamine
Carbondisulfide
Acrolein
Camphor
Sulfur dioxide
Trimethylamine
Trichloroethylene
CH3-CO-CO-CJI3
°3
H-SeH
p-
6 5
CH -
o
cs
CH2'CH-CHO
S0
(CH3)3N
CH-C1-C-C1,
Decayed cabbage
Sweet butter
Pungent
Irritating
Putrid
Empyseumatic
Fishy
Rotten
Hot fats
Aromatic
Pungent
Fishy-ammoniacal
Aromatic
2.10
25.10
37
1.10
3
3
6
7.7
15
16
30
4
250
-2
-3
-1
-------
APPENDIX A
RESULTS OF AN OPINION SURVEY CONDUCTED IN 19555
Source ^Frequency, %
Chemicals 62
Vehicles 52
Paint and Varnish 49
Food Processing 47
Domestic (homes, etc.) 45
Rendering Plants 43
Plastics 33
Oil Refineries 31
Coke Works 31
Rubber 27
Steel 25
Insulation 21
Fish 21
Gas Works 19
Pharmaceutical 19
Soaps and detergents 17
Breweries 15
a/ _ no. of times the source was mentioned
Frequency - total nQ> Qf questi0nnaries
15
-------
APPENDIX B
SOURCES OF ODORS AND THEIR COMPOSITION
Source
Chemical manufacturers:
Organic chemicals byproduct,
electrolysis
Dye-making, explosives, lacquers,
refrigeration, textiles, chemicals
Soal making, fats, oils, glycerine,
thermal decomposition, food
processing
Resins, adhesives, rubber,
paints, varnish coatings
Petroleum, petrochemicals
Pulp and paper manufacture
Fertilizers, fish wastes, spent acids
Food products, canning
Rendering, tanneries
Pharmaceuticals, breweries,
fermentation
Municipalities, dumps, lagoons,
settling ponds
Textiles, paper
Composition
Chlorine
Ammonia, hydrogen cyanide
Aldehydes, dimethyl amine
Phenolics, sulfur compounds,
formaldehyde, solvents
Hydrogen sulfide, organic sulfur
compounds, hydrocarbons
Hydrogen sulfide, organic sulfur
compounds
Amines, mercaptans, reduced
sulfur compounds
Decomposition products of nitro-
genous compounds
Amines, reduced sulfur compounds,
caproic acids, ammonia
Amines, reduced sulfur compounds
Decomposition products of nitro-
geneous compounds
Urea, starch decomposition products
16
-------
APPENDIX B Cont'd
Source
Coal gas manufacture
Natural gas
Diesel exhaust
Coffee and chicory roasting
Domestic incinerators
Composition
Sulfur compounds (hydrogen suliide,
carbon disulfide , thiophene, thiols,
carbon oxysulfide)
Hydrogen
Aldehydes
Aldehydes , hydrogen sulfide, mer-
captans, phenols, organic acids,
hydrocarbons
Organic acids ; aldehydes , hydro-
carbons , nitrogen oxides, ammonia
17
-------
APPENDIX C
Table 1.
CHEMICAL
Acetaldehyde
Acetic acid
Acetone
Acrolein
Acrylonitrile
Allyl chloride
Amine, dimethyl
Amine, monomethyl
Amine, trimethyl
Ammonia
Aniline
ODOR THRESHOLDS IN AIR
(ppm by volume)
RESPONSE
100%
Benzene
Benzyl chloride
Benzyl sulfide
Bromine
Butyric acid
2.14
0.01
0.0021
0.047
0.00047
4.68
0.047
0.0021
0.047
0.001
Carbon disulfide
Carbon tetrachloride
(chlorination of CSj
Carbon tetrachloride
(chlorination of CHj
Chloral 4
Chlorine
p-Cresol
0.1
10.0
46.8
0.047
0.314
0.00047
0.21
21.4
100.0
0.047
0.314
0.001
Dimethylacetamide
Dimethylformamide
Dimethyl sulfide
Diphenyl ether
(perfume grade)
Diphenyl sulfide
21.4
21.4
0.001
0.1
0.0021
46.8
100.0
0.001
0.1
0.0047
18
-------
Table 1. Cont'd
CHEMICAL
Ethanol (synthetic)
Ethyl acrylate
Ethyl mercaptan
Formaldehyde
Hydrochloric acid gas
Hydrogen sulfide (from Na?S)
Hydrogen sulfide gas
RESPONSE
4.68
0.0001
0.00047
1.0
10.0
0.001
0.00021
100% •
10.0
0.00047
0.001
1.0
10.0
0.0047
0.00047
Methanol
Methyl chloride
Methylene chloride
Methyl ethyl ketone
Methyl isobutyl ketone
Methyl mercaptan
Methyl methacrylate
Monochlorobenzene
Nitrobenzene
Perchloroethylene
Phenol
Phosgene
Phosphine
Pyridine
Styrene (inhibited)
Styrene (uninhibited)
Sulfur dichloride
Sulfur dioxide
Toluene (from coke)
Toluene (from petroleum)
Tolylene diisocyanate
Trichioroethylene
p-Xylene
100.0 100.0
[Above 10 ppm]
214.0 214.0
4.68 10.0
0.47 0.47
0.001 0.0021
0.21 0.21
0.21 0.21
0.0047
4.68
0.021
0.47
0.021
0.01
0.047
0.047
0.001
0.47
2.14
2.14
0.21
21.4
0.47
0.0047
4.68
0.047
1.0
0.021
0.021
0.1
0.047
0.001
0.47
4.68
2.14
2.14
21.4
0.47
19
-------
REFERENCES
1. Duffee, R.A. J. Air Pollution Control Assoc. 18, pp. 472-474. 1968.
2. Lund, H. F. Factory. October, 1965.
3. Brewer, G. L. Odor control for kettle cooking. 1962.
4. Summer, W. Methods of air deodorization. New York, Elseiver.
1963.
5. Bergen, J.J. Chemical Engineering, pp. 23,9-250. August, 1957.
6. Kenline, P. A. In quest of clean air for Berlin, New Hampshire.
US DHEW, PHS, Div. Air Pollution, Tech. Rept. A62-9, 1982.
7. Turk, A. Heating, Piping and Air Conditioning, p. 207. January,
1968.
8. Duprey, R. L. Compilation of air pollutant emission factors. US
DHEW, PHS. Natl. Center for Air Pollution Control, Publ. No. 999-
AP-42, 1968.
9. City of Cincinnati, Intercommunity Air Pollution Control Program,
Activities for 1966 and 1967.
10. Wright, R. H. Paper presented at the 55th Annual Meeting of APCA,
Chicago,. Illinois, May 20-24, 1962.
11. Studies to assess the social and economic impact of odors. Request
for Proposal, PH 22-68- Neg. 7.
12. Crocker, E.G. , and Henderson, L.F. Amer. Perfumer. 50, p. 164,
1947.
13. Byrd, J. F. , Mills, H.A. , Schellhase, C.H. , and Stokes, H.E. J.
Air Pollution Control Assoc. 14, pp.509-516. 1964.
14. Byrd, J. F. J. Air Pollution Control Assoc. 7, pp. 58-59. 1957.
15. Gex, N. F. , and Fox, F.A. J. Air Pollution Control Assoc. 7,
pp. 60-61. 1957.
22
-------
16. Prince, R.G.H. , andlnce, J, H. J. Appl. Chem. 8, pp.314-321.
1958.
17. Byrd, J. F. , and Phelps, A. H. , Jr. In: Air pollution. Vol. 2.
Analysis, monitoring, and surveying. Ed. byA.C. Stern. 2nd ed.
New York, Academic, pp. 305-327, 1968.
18. Mills, J.L. , Walsh, R.T. , Luedtke, K.D. , and Smith, L.K. J.
Air Pollution Control Assoc. 13, pp. 467-475. 1963.
19. Cederlof, R. , Edfors, M. L. , Friberg, L. , and Lindvall, T.
TAPPI, 48, p. 405. 1965.
20. Springer, K. J. An investigation of diesel powered vehicle odor
and smoke, Part II. National Air Pollution Control Adm. Final
Report, Contract No. PH 86-67-72. February, 1968.
21. Sullivan, D. C. , Adams, D. F. , and Young, F.A. Atmospheric
Environment. 2, pp. 121-133. 1958.
22. Standard method for measurement of odor in atmospheres (dilution
method). ASTM Designation D-1391-57, ASTM, Philadelphia.
pp. 185-188, 1959.
23. Duffee, R.A. , Schultz, E.G. , and Ray, H.W. Development of an
odor measurement technique for domestic gas incinerators. Pro-
ject DAG-4-M, Catalog No. 140/DR, New York, Amer. Gas Assoc.
1961.
24. Grune, W. N. Chueh, C.-F. , and Hawkins, J.M. J. Water Pollution
Control Federation, 32, pp. 942-948. 1960.
i
25. Jerman, R.I. , and Carpenter, L.R. J. Gas Chromatography. 6(5):
298-301. 1968.
26. Schneider, R.A. , Costiloe, J.R. , Vega, A. , and Wolf, S. J. Applied
Physiol. 18, pp. 414-417. 1963.
27. Ettre, L.S. J. Air Pollution Control Assoc. 11, pp. 34-42. 1961.
28. Adams, D.F. , and Koppe, R.K. TAPPI. 42, pp. 601-605. 1959.
29. May, J. Staub (English). 25(4):19-23. 1965.
30. Dravnieks, A., and Kroloszynski, B. F. J. Gas Chromatography. 5,
pp. 144-149. 1968.
23
-------
31. Wright, R.H. TAPPI. 35, pp. 276-280. 1952.
32. Douglass, I.E. J. Air Pollution Control Assoc. 18, pp. 541-544.
1968.
33. Possett, H.S. , and Reidies, A. H. I&EC, Product Res. & Dev.
4, pp. 48-50,, 1965.
34. American Soc. Heating, Refrigerating, Air-Cond. Engineers.
Tech. Com. 1.6. ASHRAE Handbook of Fundamentals, ch. 12,
pp. 173-178. 1968.
35. Walsh, R.T. J. Air Pollution Control Assoc. 17, pp. 94-97.
1B67.
36.. Borger, H. F. The solution of a major odor problem. Clean Air
Week Conf. , Cincinnati, Ohio. October, 1963.
37. Shulman, H. US DHEW, PHS, Natl. Air Pollution'Control Adm. ,
Grant No. AP 00246-04. (Project title: Kinetics of Adsorption by
Molecular Sieves.) Clarkson College of Technol. , Potsdam, N.Y.
1967.
Calvert, S. US DHEW, PHS, Natl. Air Pollution Control Adm. ,
Grant No. AP 00320-04. (Project title: Basic Study of Air Pol-
lution Control Wet Scrubbers.) Pennsylvania State Univ., University
Park, Pa. 1967.
Vaska, L. US DHEW, PHS, Natl. Air Pollution Control Admin. ,
_, Grant No. AP 00574-01. (Project title: Reversible" Metal Com-
plexes with Air Pollutants.) Clarkson College of Technol., Potsdam,
N.Y. 1967.
Hendrickson, E.R. US DHEW, PHS, Natl. Air Pollution Control
Adm. , Grant No. AP 00256-05. (Project title: Manual of Methods
for Ambient Air Sampling and Analysis.) American Public Health
Assoc. , New York, N.Y. 1967.
38. Adams, D.F. TAPPI. 48(5):83A-87A. 1965.
24
-------
APPENDIX B
WORK PLAN
Odor Pveinoval from Air by Adsorption
on Charcoal
Contract No, EHSD 71-4
Submitted by
Benjamin G. Kyle
Professor of Chemical
Engineering
N. Dean Eckhoff
Assistant Professor of
Nuclear Engineering
Kansas State University
Manhattan, Kansas 66502
September 1970
-------
WORK PLAN
In delineating the work plan for this contract research several distinct
tasks can be identified. These tasks are described below and are
scheduled on the accompanying "Milestone Chart."
1. Construction of Experimental Apparatus. A volumetric type of
adsorption system will be constructed which utilizes radioactive tracers
for measurement of the extremely low concentration of odorous compounds
in the gas phase. The gas containing the tagged odorous compound will be
circulated through a shallow bed of charcoal while the concentration of
the tagged compound in the gas phase is continuously monitored with a
radiation detector. A material balance calculation gives the adsorbent
loading corresponding to any adsorbate partial pressure. Because the
output of the radiation detector is continuous, both kinetic and equil-
ibrium data may be obtained.
Initially a gas flow cell filled with powdered anthracene crystals
will be used in conjunction with a Model 3375 Packard TRI-CARB Scintil-
lation Spectrometer, A portion of the tagged (with C, S, or H) gas
being tested will flow throagh the cell. The anthracene crystals will
serve to detect the beta particles resulting from the decay of the
radioactive isotope disintegration. The signal from the anthracene crystal
scintillator is analysed by a pulse height analyzer and the result is
stored in one or more memory units. The Model 3375 TRI-CARB system
consists, basically, of three single channel analyzers which have the
capability of varying the lower level discriminator as well as the window
-------
width for each channel. This variability allows one to discern between
three different beta particles emitting radio-isotopes, provided their
maximum energies are well separated. For example, it is quite easy to
discern H from C, but not as easy to discern C from S. However,
it should be possible to tag three compounds with H, C, and S and
to determine the relative concentration of each compound which flows
through the cell.
If the flow cell scintillation detector yields unusable data, a thin
window barrier Si semiconductor detector will be inserted in place of it.
These dectectors are not as efficient as the flow cell scintillation
detector nor can different isotopes be discerned, but they are compact,
rugged, inexpensive, and can be used as a beta particle detector.
Finally if neither of these systems work we will have to purchase the
Johnson Laboratory TRITON flow ionization chamber as listed in the
proposal. A copy of the specifications of this detector is attached.
2. Literature Search. A literature survey will be donducted covering
the following topics:
Equilibrium and kinetic data for the adsorption of odors on charcoal.
General gas phase adsorption equilibrium — theoretical treatment and
engineering correlations.
General gas adsorption kinetics — theoretical treatment and
engineering correlations.
3. Testing and Evaluating the Experimental Apparatus. The apparatus
will be tested by determining the adsorption equilibrium data for Ethyl
Mercaptan (tagged with Carbon 14) on Pittsburgh BPL activated carbon.
-------
These data can be compared with those of Grant, Manes, and Smith (1) who
report the adsorption isotherm for this system in the range 10 to 10
atmospheres.
4 Experimental Study -- Adsorption of Specific Odorous Compounds. When
the experimental apparatus and technique have been perfected, adsorption
equilibrium and kinetic data will be obtained for certain selected compounds
The specific compounds chosen for study will be selected on the basis of
their importance as air pollutants (e.g. mercaptans, disulfides5 and
aldehydes). To better understand the adsorption equilibrium behavior
of odorous compounds it will be necessary to study several compounds
within a homologous series. Adsorption equilibrium data for mercaptans
on charcoal have been reported (1) for the moderate to low pressure
range and a study of these systems should indicate whether adsorption
equilibrium data at ultra low pressure can be obtained from data at
moderate pressures.
5. Correlation of Adsorption Equilibrium Data. Concurrent with the
experimental study work will be directed toward obtaining an under-
standing of the theromodynamics of adsorption at low concentrations, and
developing correlations for the adsorption phase equilibrium data
required for design of systems for adsorption of odorous compounds. The
work of Grants Manes, and Smith (1) implies that adsorption forces depend
mainly on the nature of the functional groups comprising the adsorbate
molecule and suggests that separate adsorption equilibrium correlation
curves may be expected for each homologous series. Such a development
would allow the prediction/of adsorption equilibrium data for any member
-------
of a homologous series once these data have been determined experimentally
for one member of the series. This approach might be extended to adsor-
bates with several types of functional groups by means of a "group con-
tribution" approach similar to that employed by Pierotti et al. (2) for
correlating liquid phase solution behavior. It is also possible that
the corresponding states principle (3), which has proved useful in dealing
with gas phase interactions, would allow the correlation of adorption
equilibrium data if the significant molecular parameters can be identified.
6. Modeling of Experimental Kinetic Data. The experimental kinetic
data will be analysed using both the differential and integral approaches.
With the differential approach one determines the instantaneous rate of
adsorption at various times from the quantity adsorbed versus time data
and uses this to test rate expressions arising from various proposed
mechanisms. The appropriate mechanism is established from the condition
that for a single run parameters determined from the instantaneous rate
of adsorption evaluated at different times should be identical. In
addition to this, these parameters should be physically realistic. The
integral approach is based on integrating these various rate expressions
and comparing the resulting quantity adsorbed - time relationships with the
experimentally determined relationship. If an integrated rate expression
can be fitted to the experimental data and the evaluated parameters appear
realistic, that mechanism is said to be valid. Both the differential
and integral approaches will be considered in analyzing the kinetic data.
The differential approach has the advantage of being capable of testing
any postulated mechanism, while the integral approach is restricted to
those simpler mechanisms whose rate expressions are integrable.
-------
The object of the modeling study is to establish the rate mechanism
and to determine the dependence of the parameters in the rate expression
upon the system variables so that design of adsorption systems for odor
removal can be accomplished.
References
1. Grant, R. J, , Manes, M. , and Smith, S. 3., A.I.Ch.E.J. , j>s 403(1962),
2, Pierotti, G. J. „ Deal, C, H., and Derrs E. L., Ind. Eng. Chem., 51,
95 (1959).
3. Prausnitz, J. M. 5 "Molecular Thermodynamics of Fluid-Phase Equilibria,
Chapter 4S Prentice-Hall, Englewood Cliffs, N. J. 1969.
-------
i I U
H3
v^yr^'tsms ( Acci-jj^iortos
Low Leve! Detection •• (VIccGMrement
for Radioactive Gsces
C14 / A41 r Rn222 ( S35 c Kr05 r
C
Sensitivity: H3: 10 |j.Ci/M3 F.S. °
Accuracy ± IOX c
Sensitivity. Gamma: 50^R/hour F.S. •
Input Filter: 0.5 I'nicron Electrostatic Precipiiator °
-•••-ll--- -*'* '''••- J •"
^~-*Ht*^y
iia Compensation: to 5 mR/liour •
Flo\v Chambers: 10 liter volume • Cleanable o
Po:;i'.ive Displaccnicnt Air Pump: 1 to 10 liters/mil. <>
Alarm: N'ariablc Set Point ' Visual •• Aural «
Closed and Open Loop Operation : Gas Tigiit *
Recorder Output Remote Accessory Connector o « "
TRITON r.'odel 755C
similar to 935B except:
Sensitivity. II3: 100 (,LCi/M3 F.S. •
Sensitivity. Gamma: 0.5 mR/hour F.S. o
Flow Chanib''1)-: 1.2 liter volume «-
Flow Rate: 9 liters/ruin. »
ir,n"---
'.cTcC^-1*
TRITON l-'Gciel 10-55B
-~™^^^
similar to 755C except:
Sensitivity. H3: 50 (iCi/M3 F.S. •
Sensitivity. Gamma: 0.25 mR/hour F.S. «
Portable ' Rechargeable Ni-Cad Batteries °
Flow Rate: 2 liters/min. •
TRITOW CALIBRATOR Morfel CM
!iO:^ nZ,V;OTE ALArJ.1 Model RA-1
' Visual and Aural Alarm
irercd frojn main instrument •
•cwtcs to 500 feet or more
ion main instrument c '
Accurately Assayed ,f.., .^^
Radioactive Gas e [, .-.-:
Convenient: ^•'."T'vF'l
Self-Containcd t ^' ^_';. ~
Portable o /'? ^
Rapid Calibration: '^s--*^
3 to 5 minutes «
Low User Cost: 1000 or more calibrations '•
No Special AEC License Required «
A For wore information, caU or write. Ash far file TM.
^S2717 TT-V T T
' 1 ) I . ' f\ T..T TVT C! T' f^ T-tT ; • A TV f\ T> A O^ /^ T
-------
Contract: Odor Removal from Air by Adsorption
on Charcoal
Contractor: Kansas State University
Manhattan, Kansas
Milestones
Ml Construction of Experimental
Apparatus
M2 Testing the Experimental
Apparatus
M3 Experimental Study
M4 Literature Survey _
M5 Correlation of Adsorption
Equilibrium Data
M6 Modeling of Experimental
Kinetic Data
M7 Preparation of Final
Report
Contract No.
EHSD 71-4
Contract Dates Project(Officer
8/27/70 - 8/27/72 Dr. Belur N. Murthy
Time
J Actual
22223 Estimated
f//
1370
1172.
435- .
rt
3o
Z5-
•3
4J
ti
CJ
w
0)
•H
o
C'j..--< Ir-.tion Dntc
Actual
Kr, (. l.nuitrd
A A
2. 4
MILKfiTONK CHART
~A /\ A
3 7
------- |