EPA-650/2-74-131
DECEMBER 1974
Environmental Protection Technology Series
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environ-
mental Protection Agency, have been grouped into series. These broad
categories were established to facilitate further development and applica-
tion of environmental technology. Elimination of traditional grouping was
consciously planned to foster technology transfer and maximum interface
in related fields. These series are:
1. ENVIRONMENTAL HEALTH EFFECTS RESEARCH
2. ENVIRONMENTAL PROTECTION TECHNOLOGY
3. ECOLOGICAL RESEARCH
4. ENVIRONMENTAL MONITORING
5. SOCIOECONOMIC ENVIRONMENTAL STUDIES
6. SCIENTIFIC AND TECHNICAL ASSESSMENT REPORTS
9. MISCELLANEOUS
This report has been assigned to the ENVIRONMENTAL PROTECTION
TECHNOLOGY series. This series describes research performed to
develop and demonstrate instrumentation, equipment and methodology
to repair or prevent environmental degradation from point and non-
point sources of pollution. This work provides the new or improved
technology required for the control and treatment of pollution sources
to meet environmental quality standards.
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EPA-650/2-74-131
DETERMINATION OF HAZARDOUS ELEMENTS
IN SMELTER-PRODUCED SULFURIC ACID
by
W.H. Hedluy, S.M. Metha, andP.L. Sherman
Monsanto Research Corporation
Dayton Laboratory
Dayton, Ohio 45407
Contract No. 68-02-0226, Task 8
ROAP No. 21ADE-021
Program Element No. 1AB013
EPA Project Officer: L. Stankus
Control Systems Laboratory
National Environmental Research Center
Research Triangle Park, North Carolina 27711
Prepared for
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
December 1974
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EPA REVIEW NOTICE
This report has been reviewed by the National Environmental Research
Center - Research Triangle Park, Office of Research and Development,
EPA, and approved for publication. Approval does not signify that the
contents necessarily reflect the views and policies of the Environmental
Protection Agency, nor does mention of trade names or commercial
products constitute endorsement or recommendation for use.
This document is available to the public for sale through the National
Technical Information Service, Springfield, Virginia 22161.
11
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ABSTRACT
The Control Systems Laboratory of the Environmental Protection
Agency is presently collecting data to determine whether there
are any potentially hazardous impurities in the non-ferrous
smelter produced sulfuric acid and if these materials could
present a potential threat to vegetation and life at a later
time. Therefore, potentially hazardous element composition of
the non-ferrous smelter produced sulfuric acid was determined.
There were two aspects to this study (1) to acquire sulfuric
acid samples of non-ferrous smelter produced sulfuric acid;
(2) analyze the samples by atomic absorption spectrometry for
potentially hazardous impurities. Sulfuric acid samples were
received from seven plants and were analyzed for trace elements,
including lead, copper, zinc, mercury, arsenic, cadmium, selenium,
antimony, beryllium, and other elements detected at significant
levels during screening tests. Analyses of sulfuric acid were
also received from five other non-ferrous smelters.
iii
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TABLE OF CONTENTS
Page
ABSTRACT iiJ
I. OBJECTIVES 1
II. SAMPLE COLLECTION 2
III. SAMPLE PREPARATION AND ANALYSIS 3
IV. RESULTS AND DISCUSSION 6
V. RECOMMENDATIONS FOR ANALYTICAL METHODOLOGY 12
DEVELOPMENT
VI. REFERENCES 13
Appendix A - List of Smelter Sulfuric Acid Plants 15
Appendix B - Sample Identification 17
Appendix C - Analytical Procedure 19
Cl.O Introduction 20
C2.0 Multi-Element Screening Analysis 20
C3.0 Atomic Absorption 21
C3.1 Introduction 21
C3.2 Sample and Standard Preparation 22
C3.3 Instrument Operating Parameters 22
C3.4 Sample Analysis Methods 25
C3.4.1 General Atomic Absorption Analyses 25
C3.4.2 Special Atomic Absorption Analyses 25
C3.4.2.1 Arsenic (As) and Selenium (Se) 25
C3.4.2.2 Beryllium (Be) and Cadmium (Cd) 31
C3.4.2.3 Antimony (Sb) 33
C3.4.2.4 Mercury (Hg) 33
C3.4.3 Spectral Background Interferences 34
from Non-Atomic Absorption
C4.0 Asarco Methods for Arsenic (As) and 35
Selenium (Se)
C4.1 Determination of Arsenic in Sulfuric 35
Acid - Photometric Ag-DDC Method
C4.2 Colorimetric Determination of Se in 38
Sulfuric Acid
C4.3 Colorimetric Determination of 41
Selenium and Tellurium
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LIST OF FIGURES
Page
Figure Cl. Atomic Absorption Calibration Curve for
Cu in 25% Sulfuric Acid 26
Figure C2. Atomic Absorption Calibration Curve
for Mn in 25% Sulfuric Acid 27
Figure C3. Atomic Absorption Calibration Curve
for Pb in 25% Sulfuric Acid 28
Figure C4. Atomic Absorption Calibration Curve
for Zn in 25% Sulfuric Acid 29
Figure C5. Arsine Evolution Apparatus 37
Figure C6. Arsenic Calibration Curve 39
VI
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LIST OF TABLES
Table 1. Semi-Quantitative Emission Analyses
Table 2. Summary of Analysis for Sulfuric Acid
Samples Received by MRC Analysis Results
Table 3. Sulfuric Acid Analysis by American Smelting
and Refining Co. (ASARCO) Analysis Results
Table 4. Results of ASARCO Analyses of MRC Samples
Analysis Results
Table 5. Trace Element Quantities in Sulfuric Acid
Table 6. Trace Element Quantities in Sulfuric Acid
(American Smelting and Refining Company)
Page
4
7
8
9
10
11
Table Cl. Actual Analysis of Ultrex Sulfuric Acid
by J.T. Baker Chemical Company
Table C2. Atomic Absorption Instrument Operating
Parameters Perkin-Elmer Model 303
Table C3. Instrument Operating Parameters
23
24
32
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SECTION I
OBJECTIVES
The overall objectives of this project were to:
1. Acquire samples of sulfuric acid produced at certain
non-ferrous smelters;
2. Subject these samples to a multi-element analytical
approach to provide a preliminary indication of trace
element concentrations of potentially hazardous
impurities;
3. Analyze the samples by atomic absorption spectrometry
for potentially hazardous trace elements, including lead,
copper, zinc, mercury, arsenic, cadmium, selenium,
antimony, beryllium, and other elements detected at
significant levels during screening tests; and
4. Define the end uses of the smelter-produced acid,
determine how much acid is produced by each company,
and calculate the quantity of each element contained
in the acid produced on a yearly basis.
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SECTION II
SAMPLE COLLECTION
Monsanto Research Corporation (MRC) was to acquire sulfuric
acid samples from nine companies that operate seventeen non-
ferrous smelter plants. These companies and their plants are
listed in Appendix A. All 17 plants were contacted either by
telephone or by correspondence to outline the program and to
convince their management to participate in the study. Out of
these nine companies, six (with seven plants) agreed to supply
MRC with sulfuric acid samples from their operations. American
Smelting and Refining Company (with five plants) agreed to supply
us with only analyses of their sulfuric acid. The remaining
plants declined to supply us any sulfuric acid samples.
Each company was requested to supply random samples from their
non-ferrous smelter-produced sulfuric acid plants. Companies
involved were to supply about a pint of sulfuric acid represent-
ing three days of production during the period of one week. In
order to avoid contamination, MRC supplied each plant with three
acid-washed bottles and a brief sampling procedure. The three
samples that were received from each plant were then composited
at MRC's Dayton Laboratory for analysis.
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SECTION III
SAMPLE PREPARATION AND ANALYSIS
Seven commercial-grade sulfuric acid samples from seven plants
comprising three types of non-ferrous smelters were analyzed by
atomic absorption spectrometry for 14 elements. The samples
are identified in Appendix B. The elements analyzed were
dictated either by the work statement for this project or by
the results of emission analysis of the samples. A portion of
sample was evaporated in a heated graphite electrode. The
electrode was then analyzed by emission spectroscopy. Evaporation
of the samples in the graphite electrode could have resulted in
the loss of more volatile species, such as metal halides. This
was not a problem in that ASARCO found less than 1 ppm of chloride
in the samples they analyzed. The work statement for the project
required analysis by atomic absorption for Pb, Cu, Zn, Hg, As,
Cd, Se, Sb,and Be. Pb, Zn, Hg, As, Cd, Se, and Sb cover fairly
well the elements that are volatile and have volatile compounds
which might be found in concentrated sulfuric acid. The results
of the emission analyses are shown in Table 1.
Twenty-five ml of each sample (entire sample shaken to ensure
uniformity) was diluted to 100 ml with deionized-distilled
water. This operation was performed to permit the aspiration
of the diluted samples directly into the flame of a Perkin-
Elmer Model 303 atomic absorption spectrometer. The Perkin-
Elmer was fitted with a triple slot burner. The elements
analyzed in this manner were As, Cr, Cu, Fe, Mg, Mn, Ni, Pb,
Se, and Zn. The instrument conditions were standard as set
forth in the Perkin-Elmer manual1 except for Ni, where the
352.4 run line was used as recommended by Perkin-Elmer for iron-
containing matrices, and for Fe, where the 252.7 nm line was
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Table 1. SEMI-QUANTITATIVE EMISSION ANALYSES
(ppm by wt)
Impurity
Aluminum (Al)
Chromium (Cr)
Copper (Cu)
Iron (Fe)
Magnesium (Mg)
Manganese (Mn)
Nickel (Ni)
Lead (Pb)
Silicon (Si)
Zinc (Zn)
Sample No. 1 Sample No. 2
St. Joe New Jersey Zinc
Lead Smelter Zinc Smelter
0.032
0.93
>1.5 0.33
11.9 4.5
0.03 <0.005
0.03
4.5 0.1
0.43
0.43
4.5
Sample No. 3 Sample No. 4
City Service Missouri Lead
Copper Smelter Lead Smelter
1.19
>1.5 >3.0
0.76 2.1
0.02
<0.03
0.92 1.2
<0.32
0.32
1.52 9.2
Sample No. 5
National Zinc
Zinc Smelter
»1.5
3.0
0.01
1.52
0.16
4.5
Sample No. 6
Bunker Hill
Zinc Smelter
>1.5
9.2
0.01
0.03
1.2
<0.16
0.32
3.04
Sample No. 7
Bunker Hill
Lead Smelter
>1.5
0.76
<0.005
1.03
0.32
0.32
3.04
Note: As, Be, Cd, Hg, Sb, and Se are at a level that was not
detectable by the semi-quantitative emission analysis
method used for any of these seven samples.
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used due to higher concentrations. (Possible Hg interference of
this line is low because of the low sensitivity of Hg in a flame
[1*10 yg/m£]). Hg was analyzed by the now widely accepted cold
vapor flamelss method.2 Sb was determined using a Perkin-Elmer
model 303-0849 volatile hydride generator and methods developed
by Perkin-Elmer and others. 3ft* Be and Cd were analyzed using a
Varian Model 61 carbon rod flameless atomic absorption atomizer
power supply and a Model 63 Varian carbon rod head assembly. The
micro tube furnace was used in both cases. The micro tube furnace
is made of pyrolytic graphite and is sheathed from oxidation at
high temperatures by a flow of argon or nitrogen. Extremely high
atomization temperatures are obtainable with this furnace
(>3000°C).
All standards were prepared from regular atomic absorption stock
solutions in matrices matching the sample matrices as far as acid
concentration is concerned. Ultrex, ultra high purity acid, sold
by J. T. Baker, Co. was used to prepare standards.
Appendix C presents in detail the analytical procedure for
analysis of potentially hazardous trace element impurities in
concentrated sulfuric acid from non-ferrous smelters.
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SECTION IV
RESULTS AND DISCUSSION
Table 2 summarizes the results of atomic absorption spectrometric
analysis for potentially hazardous trace metals along with annual
production and end uses of sulfuric acid from the seven non-
ferrous smelters. The annual production and end uses of sulfuric
acid were obtained from the operators of seven non-ferrous
smelters. American Smelting and Refining Company (ASARCO)
supplied typical analyses of sulfuric acid produced at five of
their smelters and these are summarized in Table 3.
A review of the data in Tables 2 and 3 shows fairly good agree-
ment between MRC data and ASARCO for samples from similar plants.
Arsenic and selenium data were not reported in Table 2 because
their concentrations were below the MRC detection limit. MRC
contacted Mr. L. W. Anderson, Superintendent, Analytical Services
at ASARCO's Central Research Laboratories. Mr. Anderson gra-
ciously agreed to analyze our seven samples via the methods they
normally use for arsenic and selenium in concentrated sulfuric
acid samples from non-ferrous smelters. The results of these
analyses are shown in Table 4. These values are similar to the
values reported earlier by ASARCO for their acids. Anderson
stated, "These levels of both arsenic and selenium are well below
the detection limits by normal flame atomic absorption using
EDL (electrodeless discharge lamps). Atomic absorption could
possibly be used for these levels of arsenic and selenium using
hydride evolution methods." The procedures used by ASARCO for
these two analyses are reproduced in their entirety in Section
C4.0.
Tables Sand 6 show the pounds of each trace metal contained in
the sulfuric acid produced on a yearly basis and analyzed by
MRC and ASARCO respectively. The majority of the non-ferrous
smelter-produced sulfuric acid is used in fertilizer and ore
processing.
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Table 2. SUMMARY OF ANALYSIS FOR SULFURIC ACID SAMPLES RECEIVED BY MRC
ANALYSIS RESULTS
(ppra by wt.)
Sample No. 1 Sample No. 2 Sample No. 3 Sample No. 4 Sample No. 5 Sample No. 6 Sample No. 7
St. Joe New Jersey Zinc City Service Missouri Lead National Zinc Bunker Hill Bunker Hill
Trace Metals Lead Smelter Zinc Smelter Copper Smelter Lead Smelter Zinc Smelter Zinc Smelter Lead Smelter
Atomic Absorption
Method Used
Beryllium (Be)
Cadmium (Cd)
Chromium (Cr)
Copper (Cu)
Iron (Fe)
Mercury (Hg)
Magnesium (Mg)
Manganese (Mn)
Nickel (Ni)
Lead (Pb)
Antimony (Sb)
Zinc (Zn)
Annual Acid
Production
(tons/yr)
Major End
Uses
<0.001
0.11
3.28
0.47
167
0.029
0.21
1.35
1.63
2.78
0.032
0.24
70,000
Fertilizer
<0.001
0.017
0.28
0.11
22
O.OS6
0.15
0.24
<0.11
0.38
0.010
1.83
150,000
Batteries,
Plastic & Paper
<0.001
0.001
0.30
0.13
9
0.046
0.03
0.15
c
0.11
0.33
0.012
0.05
135,000
Fertilizer
Textile
<0.001
0.002
2.83
0.36
124
0.009
1.33
0.76
1.68
0.48
0.018
0.1
50,000
Fertilizer
<0.001
0.005
0.39
0.14
37
2.28
0.15
0.28
0.18
<0.13
0.003
0.07
73,500
Detergent,
Vfeter Treatment
<0.001
0.005
1.85
0.21
183
0.20
1.74
1.35
0.28
<0.13
0.026
1.1
220,
<0.001
0.114
0.78
0.18
52
0.161
0.22
0.48
0.37
2.0
0.02
0.08
000
Carbon Rod
Carbon Rod
Flame-Air-C2H2
Flame-Air-C2H2
Flame-Air-CjHj
Flameless
Flame-Air-C2H2
Flame-Air-C 2H2
Flame-Air-C 2H 2
Flame-Air-C 2H 2
Hydride Generator
Flame-Air-C 2H2
Fertilizer
Estimated accuracy of analytical procedures used to determine results listed above ±5% or better.
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CO
Table 3. SULFURIC ACID ANALYSIS BY AMERICAN SMELTING AND REFINING CO. (ASARCO)
ANALYSIS RESULTS
(ppm by wt.)
Trace Metals
Arsenic (As)
Cadmium (Cd)
Copper (Cu)
Iron (Fe)
Mercury (Hg)
Manganese (Mn)
Nickel (Ni)
Lead (Pb)
Antimony (Sb)
Selenium (Se)
Zinc (zn)
Annual Acid
Production
(tons/yr)
Major End Uses
Tacoma ,
Washington
Copper Smelter
0.44
<0.005
0.20
51.0
0.003
0.25
0.15
0.25
0.18
<0.04
0.06
44,000
Explosives, Pulp
& Paper, Fertilizer
Hayden ,
Arizona
Copper Smelter
0.08
NA
0.28
32.3
0.010
0.38
0.48
1.6
<0.01
0.04
0.94
210,000
Ore Processing
El Paso,
Texas
Copper Smelter *
0.5
NA
0.1
8.0
0.003
0.06
0.10
1.0
<0.1
0.06
0.84
168,000
Ore Processing,
Fertilizer
Corpus Christi,
Texas
Zinc Smelter
0.13
0.01
<0.06
11.5
0.20
0.11
0.07
0.27
<0.05
0.48
0.14
53,000
Ore Processing,
Petroleum Refining
Columbus,
Ohio
Zinc Smelter
0.03
<0.005
0.07
24.2
0.16
0.15
0.08
<0.07
0.12
<0.04
0.11
70,000
Ore Processing,
Fertilizer
* Also smelt zinc and lead at this plant
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Table 4. RESULTS OF ASARCO ANALYSES OF HRC SAMPLES
ANALYSIS RESULTS
(ppm wt.)
Sample No. 1 Sample No. 2 Sample No. 3 Sample No. 4 Sample No. 5 Sample No. 6 Sample No. 7
St. Joe New Jersey Zinc City Service Missouri Lead National Zinc Bunker Hill Bunker Hill
Trace Elements Lead Smelter zinc Smelter Copper Smelter Lead Smelter Zinc Smelter Zinc Smelter Lead Smelter
Arsenic (As)
Selenium (Se)
•Sample lost
0.02
*
0.12
<0.02
0.02
<0.02
0.02
<0.02
0.03
0.17
0.03
<0.02
0.03
0.03
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Table 5. TRACE ELEMENT QUANTITIES IN SULFURIC ACID
Produced on a Yearly Basis
Quantities of Trace Elements in Sulfuric Acid
flb/yr)
Trace Metals
Arsenic (As)
Beryllium (Be)
Cadmium (Cd)
Cromium (Cr)
Copper (Cu)
Iron (Fe)
Mercury (Hg)
Magnesium (Mg)
Manganese (Mn)
Nickel (Ni)
Lead (Pb)
Antimony (Sb)
Selenium (Se)
Zinc (Zn)
Annual Acid
Production
(tons/yr)
Sample No. 1
St . Joe
Lead Smelter
2.8
<0.14
15.4
459.2
65.8
23,380.0
4.1
29.4
189.0
228.2
389.2
4.5
—
33.6
70,000
Sample No. 2
New Jersey Zinc
Zinc Smelter
36.0
<0.3
5.1
84.0
33.0
6,600.0
16.8
45.0
72.0
<33.0
114.0
3.0
<6.0
549.0
150,000
Sample No. 3
City Service
Copper Smelter
5.4
<0.27
0.27
81.0
35.1
2,430.0
12.4
8.1
40.5
29.7
89.1
3.2
<5.4
13.5
135,000
Sample No. 4
Missouri Lead
Lead Smelter
2.0
<0.1
0.2
283.0
36.0
12,400.0
0.9
133.0
76.0
168.0
48.0
1.8
<2.0
10.0
50,000
Sample No. 5
National Zinc
Zinc Smelter
4.4
<0.15
0.74
57.3
20.6
5,439.0
335.2
22.1
41.2
26.5
<19.1
0.44
25.0
10.3
73,500
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Table 6. TRACE ELEMENT QUANTITIES IN SULFURIC ACID
Produced on a Yearly Basis
Produced by American Smelting and Refining Co.
db/yr)
Tacoma, Hayden, El Paso, Corpus Christi, Columbus,
Washington Arizona Texas Texas Ohio
Trace Metals Copper Smelter Copper Smelter Copper Smelter* Zinc Smelter Zinc Smelter
Arsenic (As)
Cadmium (Cd)
Copper (Cu)
Iron (Fe)
Mercury (Hg)
Manganese (Mn)
Nickel (Ni)
Lead (Pb)
Antimony (Sb)
Selenium (Se)
Zinc (Zn)
38.7
<0.44
17.6
4,488
0.26
22
13.2
22
15.8
<3.5
5.3
33.6
NA
117.6
13,566
4.2
159.6
201.6
672
<4.2
16.8
394.8
168
NA
33.6
2,688
1.0
20.2
33.6
336
<33.6
20.2
282.2
13.8
1.06
<6.4
1,219
21.2
11.6
7.42
28.6
<5.3
50.9
14.8
4.2
<0.7
9.8
3,388
22.4
21.0
11.2
<9.8
16.8
5.6
15.4
Annual Acid 44,000 210,000
Production
(ton/yr)
*Also smelt zinc and lead at this plant
168,000
53,000
70,000
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SECTION V
RECOMMENDATIONS FOR ANALYTICAL METHODOLOGY DEVELOPMENT
As a result of the detailed analytical procedure described in
Appendix C, the following investigations are recommended:
1. Development of a solvent extraction procedure for As and Se
in concentrated sulfuric acid from non-ferrous smelters.
(See Section C3.4.2.1 for description of procedure recom-
mended for investigation).
2. Check a series of samples of each element using the known
addition method of analysis: This is done as follows:
four aliquots of the samples are taken. The first aliquot
is diluted to volume with solvent. The other three aliquots
are made to volume using suitable quantities of known stand-
ards. Each of the latter three should have different quan-
tities of the element being analyzed.
Determine the absorbance (or peak height for scale expanded
samples) of each of the four solutions. Plot absorbance
versus concentration and extrapolate the resulting straight
line through zero absorbance. The intercept on the concen-
tration axis gives the concentration of the element in the
diluted sample solution.
This method allows for variations in sample matrix composi-
tion and would serve as a cross check on the answers obtained
for the sample using a standard curve.
3. A synthetic sample could be prepared with various concentra-
tions of potentially hazardous trace elements. This sample
would serve as a check on the accuracy of the methods
employed by the analyst.
12
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SECTION VI
REFERENCES
1. "Analytical Methods for Atomic Absorption," Perkin-Elmer
Corporation, Norwalk, Connecticut, 06586, USA, #303-0152
March 1973, Supplement of March 1971 edition.
2. "Methods for Chemical Analysis of Water and Wastes," EPA,
NERC, AQCL, Cincinnati, Ohio 45268, 1971, pp 121-130.
3. Fernandez, F. J. and Manning, D. C., "The Determination of
Arsenic at Sub-Microgram Levels by Atomic Absorption,"
Atomic Absorption Newsletter, 10^(4): 86-88, July-August,
1971.
4. Fernandez, F. J., "Atomic Absorption Determination of Gaseous
Hydrides Utilizing Sodium Borohydride Reduction," Atomic
Absorption Newsletter, 12^(4): 93-97, July-August, 1973.
5. "Instruction Manuals for Model 61 and Model 63 Carbon Rod
Atomizer," Varian Techtron, April 1972.
6. Kahn, H. L., Advances in Chemistry Series, Number 73, "Trace
Inorganics in Water," Chapter 12, "Prinicples and Practice
of Atomic Absorptions," pp 183-229, 1968.
7. Ramlerez-Munoz, J., Atomic Absorption Spectroscopy, Elsevier
Publishing Co., New York, New York, 493 pages, 1968.
8. Private communication with L. W. Anderson, ASARCO, February
8, 1974.
9. Stary, J., The Solvent Extraction of Metal Chelates, The
MacMillian Company, New York, New York, pp 164-167 (1964).
10. Bode, H., Neumann, F., Z. Analyst Chem. 172, pp 1-21 (1960)
11. Wyatt, P. F., Analyst 80, pp 368-379 (1955).
12. "Instruction Manual for Model 63 Carbon Rod Atomizer,"
Varian Techtron, April 1972.
13. Pustinger, J. V., Shaw, D. A., Sherman, P. L. and Snyder, "'
A. D., "Instrumentation for Monitoring Specific Particulate
Substances in Stationary Source Emissions," EPA Contract
No. 68-02-0216, EPA-R2-73-252, 415 pages, September 1973.
13
-------
References - cont'd
14. "Instructions - High Sensitivity Arsenic-Selenium Sampling
System," Perkin-Elmer Corporation, Publication 990-9832,
12 pages (1973).
15. "Determination of Mercury by Atomic Absorption Spectro-
photometric Method," The Dow Chemical Company Method CAS-AM-
70.13, Midland, Michigan 48640, June 1970.
14
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APPENDIX A
«
List of Smelter Sulfuric Acid Plants
15
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COPPER SMELTERS WITH SULFURIC ACID PLANTS
Smelter Location
Asarco Tacoma, Washington**
Asarco Hayden, Arizona**
Asarco El Paso, Texas*** t
Phelps Dodge Morenci, Arizona
Kennecott Hayden, Arizona
Kennecott Garfield, Utah
City Service Copper Hill, Tennessee*
LEAD SMELTERS WITH SULFURIC ACID PLANTS
Bunker Hill Kellogg, Idaho*
Missouri Lead Boss, Missouri*
St. Joe Herculaneum, Missouri*
ZINC SMELTERS WITH SULFURIC ACID PLANTS
Asarco Corpus Christi, Texas**
Asarco Columbus, Ohio**
Asarco Amarillo, Texas***
National Zinc Bartlesville, Oklahoma*
Bunker Hill Kellogg, Idaho*
St. Joe Monaca, Pennsylvania
New Jersey Zinc Palmerton, Pennsylvania*
* Supplied MRC with their sulfuric acid samples
** Supplied only analysis of their sulfuric acid
*** No sulfuric acid plant
t Also smelt zinc and lead at this plant
16
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APPENDIX B
Sample Identification
17
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Sample
No.
1
2
3
4
5
6
7
Type of
Smelter
Lead
Zinc
Copper
Lead
Zinc
Zinc
Lead
Company
Location
St. Joe
New Jersey Zinc
City Service
Missouri Lead
(Amex Lead Co.)
National Zinc
Bunker Hill
Bunker Hill
Herculaneum, Mo.
Palmerton, Pa.
Copper Hill, Te.
Boss, Mo.
Bartlesville, Ok.
Kellogg, Id.
Kellogg, Id.
18
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APPENDIX C
ANALYTICAL PROCEDURE
19
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ANALYTICAL PROCEDURE FOR ANALYSIS OF
POTENTIALLY HAZARDOUS TRACE ELEMENT IMPURITIES IN
CONCENTRATED SULFURIC ACID FROM NON-FERROUS SMELTERS
Cl.O INTRODUCTION
The samples of sulfuric acid from non-ferrous smelters were
screened by emission spectroscopy to establish which trace
elements were present in the samples and their approximate con-
centrations. The samples were then analayzed by atomic absorption
spectrometry to quantitatively determine the concentrations of
the potentially hazardous trace elements of interest.
C2.0 MULTI-ELEMENT SCREENING ANALYSIS
Samples of concentrated sulfuric acid from three types of non-
ferrous smelters; lead, zinc and copper; were screened by emission
spectroscopy. Two milliliters of each sample were vaporized by
dropwise addition to a heated graphite electrode. The electrodes
were heated in a metal plate holder on a laboratory hot plate.
When the evaporation was completed, ten milligrams of lithium
carbonate was added to each electrode. Standards were prepared
by weighing ten milligrams of 0.1%, 0.01% and 0.001% emission
standards, containing seventy elements in a lithium carbonate
matrix, into graphite electrodes. Sample and standard electrodes
were arced using a Spex Industries arc/spark stand with an Applied
Research Laboratories (ARL) power supply. Optical emission from
the electrodes was passed through a Bausch and Lomb (B&L) dual
illuminator to a 1.5-meter B&L grating spectrograph. Emission
spectra in the region of 250-350 nm were recorded on a 4" x 10"
Kodak photographic plate (Spectrum Analysis Plate, Type #1).
Concentrations of elements found to be present in the samples
were determined by visual comparison of emission lines in the
samples with emission lines in the standard. An ARL densitometer
20
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was used for the visual comparison. Elements of a potentially
hazardous nature found to be present by emission spectroscopy
in the samples were then quantified by atomic absorption spec-
troscopy.
C3.0 ATOMIC ABSORPTION
C3.1 INTRODUCTION
Atomic absorption spectroscopy (AAS) has come to the forefront
as an analytical tool for the quantitative determination of
trace elements in environmental samples. The advantages of
adoption of AAS for analysis of environmental samples include
minimal sample preparation, specificity and relative freedom
from interferences, usefulness for both low and high concentra-
tion of metals, speed, and accuracy. A number of reviews have
been written containing information on the basic principle of
AAS. The reviews of Kahn6 and Ramirez-Munoz7 are excellent
sources of background information for AAS.
Most instrument manufacturers of atomic absorption spectrometers
supply cookbook manuals outlining basic instrument operating
parameters for the various trace metals. In addition, these
manuals include specific methodology or references for the
determination of the various trace elements in different matrices.
The term matrix in this case refers to the gross compostion of
the sample, i.e., seawater, ground water, petrochemicals,
geological samples, biological samples, or agricultural samples.
When methods of analysis for trace elements in a particular
type of sample have not been defined, as is the case for con-
centrated sulfuric acid from non-ferrous metal smelters, the
methods must be developed by the analyst to the best of his
ability within the time and cost restraints placed by the sub-
mitter of the samples. With the information outlined above as
21
-------
a guideline, the following sections describe analytical proced-
ures for the analysis of specific, potentially hazardous, trace
elements in concentrated sulfuric acid samples from non-ferrous
smelters by atomic absorption spectroscopy.
C3.2 SAMPLE AND STANDARD PREPARATION
A sample to be analyzed by AAS must in some way be vaporized to
give a significant population of atoms in the ground state then
passed through a beam of light. Three main devices for pro-
ducing the vapor needed are a flame, cold vapor generation, and
carbon rod atomization. A flame is the most general type of
vaporization. The sample is normally nebulized into the flame
as an aerosol from an aqueous solution. The nebulizer of our
P. E. Model 303 atomic absorption spectrometer will accept acid
concentration up to approximately 25%. The concentrated sulfuric
acid samples from non-ferrous smelters were diluted to 25% of the
origianl concentration with deionized-distilled H20 so they could
be nebulized directly into the flame. Standards and blank were
prepared by proper dilution of atomic absorption stock solutions
(made by Harleco, 60th and Woodbine Ave., Philadelphia, Penn.,
19143) with sulfuric acid to match the matrix (25% sulfuric
acid) of the samples. The sulfuric acid used was Ultrex, J. T.
Baker, Co. with low trace elements content. The actual analysis
of sulfuric acid is given in Table Cl.
C3.3 INSTRUMENT OPERATING PARAMETERS
Table C2 is a listing of all of the trace elements analyzed in
the concentrated sulfuric acid samples from non-ferrous smelters
and the instrument operating parameters for each. The instru-
ment used was a Perkin-Elmer Model 303.l The operating param-
eters listed include: hollow cathode lamp manufacturer (all
of the hollow cathode lamps are single element cathode except
Cr, Cu, Fe, Mn and Ni which were in one multicomponent lamp);
22
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Table Cl. ACTUAL ANALYSIS OF ULTREX SULFURIC ACID SOLD BY
J. T. BAKER CHEMICAL COMPANY
Formula: H2SOi* ACTUAL ANALYSIS
FW 98.08
Assay (H2SOit) 95.3%
Residue after Ignition 1 ppm
Specific Gravity at 60°/60°F 1.84
NON-METALLIC IMPURITIES
in parts per million (ppm)
Ammonium (NH4) 0.8
Arsenic (As) 0.001
Boron (B)* 0.02
Chloride (Cl) <0.05
Nitrate (N03) 0.2
Phosphate (PO^) <0.05
Selenium (Se) 0.2
Silicon (Si)* 0.04
METALLIC IMPURITIES*
in parts per billion (ppb)
Aluminum (Al) 3
Barium (Ba) <1
Bismuth (Bi) <1
Cadmium (Cd) <1
Calcium (Ca) 20
Chromium (Cr) 1
Cobalt (Co) <1
Copper (Cu) 2
Iron (Fe) 3
Magnesium (Mg) 3
Manganese (Mn) 0.4
Mercury (Hg) <10
Nickel (Ni) < 1
Potassium (K) <10
Sodium (Na) 90
Strontium (Sr) < 1
Zinc (Zn) < 1
*Average value for three samples vaporized and analyzed spec-
trographically (DC-arc, indium internal standard in graphite
matrix against commercial standards), reading of lines in
2450-3875 A region; strontium, calcium, and barium determined
on a single composite sample, reading at 4078 A, 4227 A, and
4554 A, respectively; key elements found absent are reported
as < (less than) the detection limit.
23
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Table C2. ATOMIC ABSORPTION INSTRUMENT OPERATING PARAMETERS PERKIN-ELMER MODEL 303
Element
Arsenic (As)
Berryllium (Be)
Cadmium (Cd)
Chromium (Cr)
Copper (Cu)
Iron (Fe)
Mercury (Hg)
Magnesium (Mg)
Manganese (Mn)
Nickel (Ni)
Lead (Pb)
Antimony (Sb)
Selenium (Se)
Zinc (Zn)
Hollow
Cathode
Lamp Mfq.
Perkin-Elmer
Perkin-Elmer
Westinghouse
Westinghouse
Westinghouse
Westinghouse
Perkin-Elmer
Perkin-Elmer
Westinghouse
Westinghouse
Perkin-Elmer
Jarrell-Ash
Westinghouse
Perkin-Elmer
Lamp
Current
ma.
18
30
12
25
24
25
10
12
25
25
30
20
14
15
Wave
Length
run.
193.7
235.0
228.8
357.9
324.7
252.7
253.6
285.2
279.5
352.4
283.3
217.0
196.0
213.9
Gain
4.6
3.0
1.0
3.0
3.9
4.5
3.0
1.0
4.5
3.4
1.3
4.8
4.0
2.8
Slit
Width
nm.
2.0
0.14
0.2
0.7
0.2
0.2
0.2
0.7
0.2
0.2
0.7
0.2
2.0
0.7
Air
Flow
1/min.
—
—
26.5
25.2
25.2
—
26.5
26.5
26.5
25.7
—
—
25.2
Acetylene
Flow
t/min.
—
—
4.8
4.2
3.9
~
4.0
4.1
4.1
4.9
~
—
4.2
Scale
Expansion
Factor
10
1
3
10
10
10
1
3
1
3
3
10
10
1
10
3
Noise
Suppression
3
1
2
3
3
3
1
2
1
2
3
2
3
2
3
3
-------
lamp operating current in milliamps; wavelength used for the
analysis in nanometers; amplifier gain potentiometer setting;
slit width in nanometers; the air flow rate in liters/minute
and the acetylene flow in liters/minute, where these are appli-
cable; scale expansion factor, and noise suppression setting.
C3.4 SAMPLE ANALYSIS METHODS
C3.4.1 General Atomic Absorption Analyses
Cr, Cu, Fe, Mg, Mn, Ni, Pb, and Zn were analyzed in the concen-
trated HaSOit samples using an air-acetylene flame by nebulizing
the dilute samples described in section C3.2 directly into the
flame. The calibration curves for Cu, Mn, Pb and Zn are shown
in Figures Cl, C2, C3, and C4. The calibration curves are
typical of the curves developed for the elements listed above.
The eight elements listed above were all easily analyzed by
conventional atomic absorption techniques. The remaining six
elements (As, Se, Be, Cd, Sb, and Hg) are more difficult to
analyze by this technique. Each requires some special treat-
ment; therefore, they are described separately.
C3.4.2 Special Atomic Absorption Analyses
C3.4.2.1 Arsenic (As) and Selenium (Se)
Arsenic and selenium are probably the two most difficult elements
of the fourteen elements listed to analyze. Their primary
resonance wavelengths are 193.7 and 196.0 nm, respectively.
These wavelengths are in the vacuum ultraviolet region where
almost all chemical species have at least some absorption char-
acteristics. These absorptions and the noise associated with
flickering within the flame increase the lower detection limits
for these elements. Five methods of analysis were attempted:
25
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40-
N)
0 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20 0.22 0.24
Copper, micrograms / milliliter
Figure Cl. Atomic Absorption Calibration Curve for Cu in 25% Sulfuric Acid
-------
90
80
70
60
E
E
50
• 40
S
QL.
30
20
10
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
Manganese, micrograms / milliliter
Figure C2. Atomic Absorption Calibration Curve
for Mn in 25% Sulfuric Acid
27
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no
100
90
80
70
E 60
E
c.
en
« 50
03
O)
O_
30
20
10
1.0 2.0
Lead, micrograms / milliliter
3.0
Figure C3. Atomic Absorption Calibration Curve
for Pb in 25% Sulfuric Acid
28
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240
220
200
'180
160
140
120
.2-100
CJ
X
s
80
60
40
20
.1 .2 .3 .4 .5 .6 .7
Zinc, micrograms / milliliter
.8 .9
1.0
Figure C4. Atomic Absorption Calibration Curve
for Zn in 25% Sulfuric Acid
29
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1. Flame absorption - Air-acetylene flame
2. Flame Absorption - Argon-hydrogen-entrained air flame
3. Carbon Rod Atomization - (See Be and Cd analyses)
4. Hydride formation followed by flame absorption -
(See Sb analyses)
5. Addition of 1 ml of 10% hydroxylamine hydrochloride to 40 ml
of 25% sulfuric acid samples, standards and blanks followed
by flame absorption - argon-hydrogen-entrained air flame.
In the arsenic analyses using Method 5, average signal for the
samples was 15-27 mm above the average signal observed for the
blank solution. However, since the width of the noise in the
signal is ^25 mm, the minimum detection limit would be ^50 mm
if the rule, that the minimum detection limit is a signal twice
as large as the width of the average noise, is applied. For
selenium average signal for the samples was 9.5-34 mm, average
noise was 18 mm and minimum detection limit was 36 mm. There-
fore, since the results were below the detection limit of the
method, they will not be reported. The values obtained by
ASARCO for these samples are shown in Table 4. The author
recommends a solvent extraction procedure for separating As
and Se from sulfuric acid be investigated. Diethylammonium
diethyldithiocarbamate has been found to form quantitatively
extractable chelates with As and Se from sulfuric acid samples
as concentrated as 10 N9'10/11.
The extracted chelate in an organic solvent could be analyzed
by a number of techniques. The organic solvent may be atomized
directly into the flame or applied to the carbon rod and
analyzed by flameless absorption. The organic solvent can
be evaporated and the As and Se containing chelate residue
analyzed by x-ray fluorescence. By shaking the organic solvent
30
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with a basic solution (pH > 8), the chelate is destroyed and
the As and Se are transferred to the aqueous layer. This
aqueous layer may then be used for flame or flameless atomic
absorption. The aqueous layer could also be analyzed via a
colorimetric analysis.
C3.4.2.2 Beryllium (Be) and Cadmium (Cd)
Beryllium and cadmium were analyzed using a Varian Model 61
carbon rod flameless atomic absorption atomizer power supply
and a Model 63 Varian carbon rod head assembly. The reader
is referred to Varian instruction manuals5*12 for a complete
description of the carbon rod assembly. The microtube furnace
was used in both cases. The micro tube furnace is made of
pyrolytic graphite and is sheathed from oxidation at high tem-
peratures by a flow of argon. Extremely high atomization
temperatures are obtainable with this furnace (>3000°C). The
methodology for analysis of Be and Cd in strongly acid solutions
had been developed by MRC on an earlier EPA contract13. The
carbon rod assembly is used for Be analyses because the refrac-
tory nature of Be compounds requires a very high temperature to
atomize the compounds. Lower detection limit for Be is 5x 10"10
gram/milliliter using the carbon rod assembly to analyze 25%
sulfuric acid samples. Dry, ash, and atomize times and voltages
for Be analysis using the carbon rod assembly are shown in Table C3<
Cadmium analyses of the 25% H2SOU samples and standards were per-
formed using both an argon-hydrogen-entrained air flame for
higher concentration samples and the carbon rod assembly. The
lower detection limit using the flame was 1.6 x 10~8 gram/
milliliter and 1 x 10~10 gram/milliliter using the carbon rod
31
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Table C3
Instrument Operating Parameters
For a Varian Model 63 Carbon Rod Atomizer
Used with a Perkin-Elmer Model 303
Atomic Absorption Spectrometer
Dry Cycle Ash Cycle Atomize
Cut-Off
Time Voltage Time Voltage Ramp Voltage
Element (sec) (volts) (sec) (volts) Rate (volts)
Be 12 5 10 7 4 9
Cd 12 5 10 7 6 5
32
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assembly. Operating parameters for the carbon rod are shown
in Table C3. Flow rate of argon when using the carbon rod
assembly was 4.5 liters/minute.
C3.4.2.3 Antimony (Sb)
Antimony was determined using a Perkin-Elmer Model 303-0849
volatile hydride generator and methods developed by Perkin-
Elmer. 3/11* Forty milliliters of 25% sulfuric acid sample is
reacted first with a reducing agent such as stannous chloride
then with a source of nascent hydrogen. The hydrogen produced
reacts with Sb to form stibine, SbH3, a gas. The hydrogen and
stibine are collected in a balloon-type reservoir after the
reaction is complete, two minutes for Zn, 30 seconds for sodium
borohydride. The gas is swept from the generator and reservoir
to the argon-hydrogen-entrained air flame by argon. Standards,
blanks and samples are all treated in the same manner. Note:
Although the hydrides of arsenic and selenium can be formed in
a similar manner, attempts at using this method for arsenic and
selenium were not successful.
C3.4.2.4 Mercury (Hg)
The basic method for analysis of Hg is based on a procedure
originally developed by Dow Chemical Company15 for analysis of
Hg in water. An aliquot of sample is placed in an erlenmeyer
flask, 1 milliliter of 5% potassium permanganate is added and
a watch glass is placed on the top of the flask. The sample
is heated on a hot plate until the sample boils for two minutes.
After the sample is cooled to room temperature, 10% hydroxylamine
hydrochloride is added dropwise to destroy excess permanganate.
An aliquot of the sample is transferred to a bubbler flask and
2 ml of 40% stannous chloride in 9N hydrochloric acid is added
33
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to the flask. This reduces all Hg present to Hg°. A flow of
argon is then diverted through the bubbler and carries Hg vapor
through a 10-crn gas cell in the beam of the atomic absorption
spectrometer.
C3.4.3 Spectral Background Interferences from
Non-Atomic Absorption
Non-atomic absorption is due to molecular absorption and/or
light scattering by solid particles in the flame or other form
of atomization. Molecular absorption is caused by the presence
of molecular species in the flame which absorb light at the
same wavelength as the element resonance line. Light scatter-
ing by particles in the flame results when solutions of high
total solids are aspirated into a burner. Both types of non-
atomic absorption occur over wide spectral bands (>10 nm)
compared with the 0.01 nm absorption for atomic lines in the
flame.
Corrections for non-atomic absorption interferences can be made
by comparing the absorption at a specific wavelength obtained
with a hollow cathode lamp versus the absorption values obtained
with a continuum lamp (hydrogen or deuterium). The absorption
measurement obtained with a hollow cathode line source is the
sum of an element's atomic absorption and the non-atomic
absorption. The absorption measured with the continuum lamp
is, to a close approximation, the non-atomic absorption only.
The sample's true atomic absorption is the absorption measured
using the hollow cathode line source less the absorption
measured using the continuum source.
A hydrogen continuum lamp was used to check for non-atomic
absorption during the analyses described in the previous
sections. No non-atomic absorption was observed for any of
the elements analyzed.
34
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C4.0 ASARCO METHODS FOR ARSENIC (As) AND SELENIUM (Se)
The methods described in this section are the procedures ASARCO
normally uses for measurement of low levels of arsenic and
selenium in concentrated sulfuric acid samples. MRC has not
tried these methods, therefore MRC cannot substantiate the
validity of these methods. The methods are reproduced exactly
as submitted to MRC by ASARCO. With the selenium procedure, an
additional pretreatment of "black acid" samples should be made
by cautiously mixing 5 ml of 30% H2O2 with the H2SOt| aliquot in
a 250 ml beaker and heating until the acid is decolorized and
the H202 decomposed. After cooling, mix with the calculated
amount of water in step 4 of the procedure and proceed from
there.
C4.1 DETERMINATION OF ARSENIC IN SULFURIC ACID - PHOTOMETRIC
Ag-DDC METHOD
Principle
Arsine is evolved with granulated zinc and hydrochloric acid
and absorbed in a silver diethyldithiocarbamate-pyridine
solution. The red color is measured photometrically at 540 nm.
Reagents
Standard Arsenic - Dissolve 0.132 g of arsenic trioxide (As203)
in 50 mil water containing 5-6 pellets of NaOH. Transfer to a
1-liter volumetric flask and dilute to the mark with water.
(1 ml = 0.1 mg As). Transfer by pipet 5.00 ml of this solution
to a 100-ml volumetric flask and dilute to the marks with water.
(1 ml - 0.005 mg As).
Ag-DDC - Dissolve 0.5 g of silver diethyldiethiocarbamate
(Fisher #5-666) in pyridine and dilute to 100 ml with pyridine.
35
-------
15% KI solution - 15 g KI dissolved in 100 ml water.
40% SnCl2 solution - 40 g SnCl2 dissolved in concentrated HC1.
Dilute to 100 ml with concentrated HC1.
Apparatus
This procedure is written for use with a photometer employing
a 2-cm cell. See Figure C5.
0.001 mg to 0.25 mg As.
Procedure
Transfer a 5 ml aliquot (^9.2 g) of the sulfuric acid sample to
a 125 ml Erlenmeyer flask. Add cautiously 5 ml HN03 and heat
to dense fumes. If charring of any organics present begins to
occur, add additional HNC>3 to prevent any losses of arsenic.
Heat to dense fumes. Cool to room temperature. Wash down
walls of flask with a small amount of water and refume. Cool.
Add 50 ml of water and cool again. Add 10 ml HC1.
Add 2 ml of 15% KI solution and then decolorize with 1 ml of
SnCl2 solution. Let stand at room temperature 15-20 minutes.
Assemble the apparatus. Have the 15 ml of Ag-DDC solution in
the tall graduate ready. Quickly add 5.0 gm of 40 mesh granu-
lated Zn (low in As), restopper the flask and evolve arsine
for 20-30 minutes.
Disconnet apparatus, transfer Ag-DDC pyridine solution to a
dry photometer tube and determine % T. at 540 nm. Calculate %
As. Run blanks through entire procedure. Large amounts of Sb
interfere Sb reads ^8% of the As.
36
-------
00
One Hole
Rubber Stopper
6 mm I.D. Glass Tubing
Lead Acetate Impregnated
Glass Wool Plug
Glass Wool Plug
(unimpregnated)
Glass Tubing with
Constricted Lower End
15 ml Ag-DDC/ Pyridine
125 ml Erlenmeyer Flask
25 ml Graduate
Figure C5. Arsine Evolution Apparatus
-------
Calibration
Transfer 0.0, 1.0, 2.0, 3.0 and 5.0 ml of Standard Arsenic
Solution (1 ml = 0.005 mg As) to each of five 125-ml Erlenmeyer
flasks, respectively. Add 50 ml water, 5 ml I^SO/t and 10 ml HC1
to each flask, cooling between additions. Add 2 ml of 15% KI
solution, and 1 ml of 40% SnCl in HC1. Let stand 15-20 minutes.
Transfer 15.0 ml of Ag-DDC solution to a 25-ml graduate. Add 5 g
of 20 mesh zinc and quickly assemble the apparatus. After 20-30
minutes, disassemble and transfer the absorbing solutions to
photometer tubes and measure photometrically. Plot mg As versus
transmittance on semi-log paper (Figure C6).
C4.2 CQLORIMETRIC DETERMINATION OF Se IN SULFURIC ACID
Principle
A 50-ml aliquot of the sulfuric acid is diluted with enough water
to give a 6 normal solution. An amount of ammonium chloride
equivalent to the amount of H2SOit present is added, yielding a
solution that is 6BN in H+ and Cl~. An arsenic separation is
done on this solution, and the Se determination is completed in
the usual manner.
Procedure
1. If the normallity of the I^SOit is unknown, determine it by
titrating a 1.0-ml aliquot with IN NaOH, using methyl orange
or any other appropriate indicator. The reading on the buret
will be the normality of the acid.
Example: A 35.0 ml reading is equivalent to 35.0 N acid.
38
-------
.005
.010 .015 .020 .025
Milligrams of Arsenic per 15 ml
.030
Figure C6. Arsenic Calibration Curve
39
-------
2. Calculate the volume to which 50 ml of the acid must be
diluted to give a 6N solution, using the formula ml x N =
ml x N.
Example: (for 35.0 N
50 x 35.0 = ml x 6
vol. = 292 ml
3. With a graduated cylinder measure a volume of distilled
water about 100 ml less than that calculated in Step 2 and
add it to a 800 ml beaker.
4. Add 50.0 ml of the B^SOi, to the distilled water by pipet,
swirling the tip of the pipet in the water and cooling, if
necessary, to prevent the water from boiling excessively.
5. Sometimes E^SOj, samples contain S02. If there is any odor
of S02 in the sample, boil the solution from Step 4 until
no more odor of SO 2 can be detected. (If this is not done,
the S02 will react with the hypophosphorus acid in step 8
to form sulfur) .
6. Calculate the weight of NH^Cl that will be equivalent to
50 ml of the acid.
Example: Normality x liters = number of equivalents
No. of equivalents x equivalent wt. of NHitCl = grams
of NH^Cl
35.0 x .050 = 1.75 equivalents
1.75 x 53.8 = 94.2 grams of NH,,C1
7. Add the NH^Cl to the 800 ml beaker and add enough hot dis-
tilled water to bring the volume up to that calculated in
Step 2. (Sometimes it is necessary to add a little more
water to get all the NHi,Cl into solution, especially if
the acid is strong.)
40
-------
8. Add 5 ml of arsenic solution (1.0 mg As/ml) and 25 ml of
hypophosphorous acid to the 800 ml beaker. Cover, place
on the hot place, and boil for 10 minutes.
9. Remove from the hot plate and add 50 ml of H20. Cool and
filter through a No. 42 filter paper or a 1.2y Millipore.
If NH^ salts come out during the filtration, add a little
hot water.
10. Finish the Se determination in the usual manner.
11. Calculate the ppm Se in the H2SOt, according to the formula:
mg Se _ _
.050 x sp.gr. of I^SOi, ~ Ppm Se
C.4.3 COLORIMETRIC DETERMINATION OF SELENIUM AND TELLURIUM
Discussion
The following methods for Se and Te both begin in the same way:
The sample dissolution is the same for both and both are separated
from other constituents by an arsenic co-precipitation. If a
substance is to be analyzed for both Se and Te, a single sample
can often be used as the starting point for both determinations,
at a great saving of time and effort. This is done by dissolving
the arsenic precipitate containing the Se and Te and diluting it
to 100 mis. Then appropriate sized aliquots are drawn for Se and
Te and the determinations completed individually.
SELENIUM
Application
The method applies to the analysis of concentrates, matte, speiss,
slags, dusts, sinters, calcines, blister copper, anode copper
and copper tankhouse electrolytes. For the determination of Se
41
-------
in cathode copper, lead bullion, refined lead, arsenic, tellurium,
etc., and solders, see methods applying specifically to these
substances.
The Method in Brief
The sample is decomposed with HMOs, HF, and HClOi*. The first
two acids and Si02 are expelled by taking to HClOi* fumes. The
resulting mixture is taken up with 1:1 HC1, arsenic solution is
added, and the Se (together with any Te present) co-precipitated
with the As by reduction with hypophosphorous acid. The arsenic
precipitate is dissolved and treated with 3,3'-diaminobenzidine
at pH 2-3. The intensely yellow-colored compound of Se and
diaminobenzidine is extracted with toluene at pH 8 and measured
photometrically at 420 my.
Interferences
This method is specific for Se. There are no known interferences.
Reagents
Arsenic Solution - Dissolve 0.25 g of arsenious oxide (As2O3)
plus 10 pellets of NaOH in 10 ml of distilled water by warming.
Dilute to 200 ml and mix.
META Cresol Purple Indicator Solution (MCP) - Dissolve 0.10 g
of meta cresol purple plus 1 pellet of NaOH in 10 ml of dis-
tilled water by warming. Dilute to 100 ml and mix.
EDTA Solution (2%) - Dissolve 20.0 g of disodium ethylenediamine-
tetraacetate, dihydrate, in 900 ml of distilled water. Dilute
to 100 ml and mix.
Formic Acid Solution (1:9) - Mix 20 ml of formic acid with 180 ml
of distilled water.
42
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Diaminobenzidine Solution (0.5%) - Dissolve 0.100 g of 3,3'-
diaminobenzidine (tetra) hydrochloride in 20 ml of distilled
water. Prepare fresh daily and store under refrigeration.
Only enough solution should be prepared at a time as will be
used immediately, as the reagent in aqueous olution is not very
stable and is quite costly.
Standard Selenium Solution (1 ml = 0.02 mg Se) - Dissolve 0.5000 g
of high purity selenium in 20 ml of nitric acid and boil to expel
oxides of nitrogen. Cool and dilute to 500 ml with distilled
water and mix. Transfer a 10.0-ml aliquot to a 500 ml volumetric
flask, dilute to volume and mix. 1 ml = 0.02 mg Se.
Preparation of Calibration Curve
(a) Transfer 0.00, 0.50, 1.00, 2.00, 3.00 and 4.00 ml of standard
selenium solution (1 ml = 0.02 mg Se) to each of six 250 ml
copper assay flasks respectively, using Mohr pipettes. (3)
To each flask add 3 ml of HClOi, and evaporate to not less
than 2 ml volume. Cool somewhat, add 50 ml of distilled
water, and boil for about 1/2 to 1 minute. Cool to room
temperature.
(b) Add 5.0 ml of 2% EDTA solution and 2 drops of MCP indicator
solution. Neutralize with NH^OH dropwise just to the yellow
color of the indicator. (2) Add 2.0 ml of formic acid
(1:9) and 2.0 ml of freshly prepared diaminobenzidine solu-
tion. Heat for 5 min. in a boiling water bath. A 600 ml
beaker with approximately 200 ml of water makes an ideal
bath. Cool to room temperature.
(c) Neutralize with concentrated ammonium hydroxide dropwise to
the purple color of the indicator pH = 8 (11-12 drops of
cone. NHijOH are required.) Pour each solution into a 125 ml
separatory funnel. (3) Drain well but do not wash. From a
43
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burette, add 12.0 ml of toluene, stopper and shake
vigorously for 30 seconds. Allow the layers to separate
and drain and discard the lower aqueous layers. Filter
the organic layers through dry, folded, 9 cm Whatman No. 41
H papers into colorimeter tubes. Measure at 420 my
against the reference blank.
(d) Plot the photometer readings against milligrams of
selenium on semi-logarithmic paper.
Procedure
Transfer a 1-g sample (1) to a 250 ml copper assay flask (3).
Add 10 ml of HNO3, 5 ml of HC10U/ and 4-6 drops of HF (1-2 ml
of HF for slags). Heat on a hot plate until brown fumes have
subsided, then swirl the flask over a Meker burner until heavy
fumes of HClOi, appear. If beads of sulfur remain, set the flask
on the hot plate until they are oxidized or burn off. Cool some-
what. Add 3-4 ml of water and swirl to break up the cake. Add
100 ml of 1:1 HC1, 2 ml of arsenic solution, and 1 or 2 Hengar
granules. Mix. (If a clear solution is not obtained at once,
the solution may be warmed, but should not be boiled.) Add 15 ml
of 50% hypophosphorous acid (H3P02) and swirl to mix. Place the
flask on the hot plate and simmer gently for approximately 10
minutes until the arsenic precipitate coagulates. CAUTION:
Do not allow any of the solution to splash or leak on to the
hot plate (4). After the precipitate has coagulated, cool to
about 70°F by allowing the flask to stand on the bench top for
10-15 minutes (5).
Filter the warm solution through an 11 cm Whatman No. 42 filter
paper. Wash the flask three times with a hot solution of 1-1
HC1 containing about 3-4 ml of H3PO2 per 100 ml of solution,
pouring the washings into the filter. Wash the paper two
additional times with small portions of the HC1-H3P02 wash
44
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solution. Wash the flask three times with small portions of hot
distilled water, pouring the washings into the filter. Wash the
paper 10 additional times with small portions of hot distilled
water. Test this water coming out of the funnel with pH paper;
if it is still acid, continue washing until it is neutral.
Transfer the paper and precipitate back to the original flask.
Wipe out the funnel with a small piece of damp filter paper to
gather any precipitate adhering to the funnel and add to the
flask. Add 10 ml of nitric acid and 5 ml of perchloric acid
to the flask. Place the flask on the hot plate and boil until
the paper is destroyed (6). Swirl the flask over the Meker
burner until dense fumes of perchloric acid appear, but do not
evaporate to less than 2 ml. Cool somewhat, add 50 ml of dis-
tilled water and boil for 1/2 to 1 minute. Cool to room
temperature. (If the Se in the sample is higher than 0.007%,
dilute to volume and pipet an aliquot (1). Add enough distilled
water to the aliquot to bring it up to 50 ml).
Prepare a blank from 10 ml of HN03 and 5 ml of HClOi, fumed down
to 2 ml in a copper assay flask. Add 50 ml of distilled water
and boil for 1/2 to 1 minute. Cool to room temperature.
Continue in accordance with paragraphs (b) and (c) under Prep-
aration of Calibration Curve.
By referring to the calibration curve, determine the milligrams
of Se present and compute the percentage of Se in the sample:
Milligrams of Se
•"• IB 06
grams of sample x 10
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Notes
(1) The useful range of the colorimetric curve is from about
0.005 mg Se to about 0.07 mg Se. For a 1-g sample, this
corresponds to 0.0005% Se to 0.007% Se. If the Se present
in the sample is in the 0.005% to 0.07% range, use a 1-g
sample but dilute the dissolved arsenic precipitate to
100 ml in a volumetric flask and pipet a 10 ml aliquot.
This corresponds to a 0.1 g sample.
If the Se present is in the 0.05% to 0.7% range, use a
1-g sample but dilute the arsenic precipitate to 500 ml
in a volumetric flask and pipet a 5 ml aliquot, corres-
ponding to a 0.01-g sample. Amounts of Se higher than
0.5% are within the range where they can be done by atomic
absorption which is much faster and easier.
Samples of copper tankhouse electrolyte need not be given
the preliminary decomposition with HNOs, HC101+, and HF,
but may be combined directly with the 100 ml of 1:1 HC1.
(2) The indicator color at this point must be just barely
yellow, so that when the formic acid is added, the color
will change from yellow to orange or pinkish-orange.
(3) A set of flasks and separatory funnels should be cleaned
thoroughly and set aside for use only in this selenium
determination to avoid contamination. It should be kept
in mind, however, that repeated use with HF results in
gradual erosion of the copper assay flasks and the devel-
opment of thin spots, especially on the bottom. Cases are
known where thin copper assay flask have developed leaks
while on the hot plate resulting in loss of samples and
even explosions (See Note 4). To avoid this, it is
46
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essential that the copper assay flasks be tested prior to
each use by tapping the bottoms on a pointed wooden object
such as the corner of a beaker tray or cabinet door. This
treatment will crack or break flasks with thin bottoms.
(4) If the solution containing hypophosphorous acid and per-
chloric acid should leak, bump, or be spilled so that
the solution comes into direct contact with the hot plate,
spontaneously flammable phosphine is formed. With the
oxidant, concentrated perchloric acid, also present, a
small but violent explosion may result.
For this reason, the solutions should not be boiled hard,
one or two Hengar granules should be present, and flasks
with thin bottoms should not be used.
(5) Cooling to about 70°C is mandatory; if the 1:1 acid solu-
tion is much hotter than 70°C, the filter paper may break.
(6) Destruction of filter paper with HN03 and HCIO^ is done by
boiling the mixture at a moderate (not fast) rate. Oxida-
tion of the last traces of organic matter occurs in about
10 - 15 minutes and is indicated by a rather sudden onset
of vigorous bubbling. The bubbling subsides in 5 - 10
seconds leaving a colorless solution of HClOit which may
then be fumed over a Meeker burner. If, instead of bub-
bling, the solution turns suddenly dark, more HN03 should
be added. The need for this arises only when the
and the paper are boiled too fast.
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TECHNICAL REPORT DATA
(Please read Inunctions on the reverse-be fore-completing)
1. REPORT NO.
EPA-650/2-74-131
3. RECIPIENT'S ACCESSION>NO.
4. TITLE AND SUBTITLE
Determination of Hazardous Elements in Smelter-
Produced Sulfuric Acid
S. REPORT DATE
December 1974
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
W. H.Hedley, S.M.Mehta, and P.L.Sherman
8. PERFORMING ORGANIZATION REPORT NO,
MRC-DA-419
9. PERFORMING OR6ANIZATION NAME AND ADDRESS
Monsanto Research Corporation
Dayton Laboratory
Dayton, Ohio 45407
10. PROGRAM ELEMENT NO.
1AB013; ROAP 21ADE-021
11. CONTRACT/GRANT NO.
68-02-0226, Task 8
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
NERC-RTP, Control Systems Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final; Through 11/74
14. SPONSORING AGENCY CODE
IS. SUPPLEMENTARY NOTES
is. ABSTRACT
repOrt presents results of analyses of potentially hazardous impur-
ities (trace elements) in sulfuric acid produced by non-ferrous smelters. Sulfuric
acid samples were obtained from acid plants attached to copper, lead, and zinc
smelters. Results of analyses provided by some smelters are also included. Trace
elements subjected to qualitative and quantitative determinations in this study
include: Pb, Cu, Zn, Hg, As, Cd, Se, Sb, and Be, as well as other elements
detected in significant concentrations during screening tests. Based on this
analytical data, the report indicates yearly outputs of hazardous trace elements
contained in smelter-produced acid for possible consumption in a variety of
industries. The report also presents information on analytical methods and
procedures used in acquiring the reported data.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Croup
Air Pollution
Sulfuric Acid
Smelters
Copper
Lead (Metal)
Zinc
Chemical Analysis
Air Pollution Control
Stationary Sources
Trace Elements
13B , 07D
07B
11F
8. DISTRIBUTION STATEMENT
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
54
Unlimited
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
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