United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S7-81-084 July 1981
Project Summary
The Analysis of Oil Shale
Wastes: A Review
John R. Wallace
This report summarizes the current
status of methods for chemical analysis
of oil shale effluents. It focuses on
inadequacies in standard methods,
adapted to oil shale analysis, particu-
larly addressing needs of chemists,
engineers, and biologists attempting
to select an analytical scheme suitable
for oil shale waste, including sampling,
analysis, and quality assurance. The
literature has been searched exten-
sively, especially for methods of
questionable validity, so that alternate
techniques could be included.
This Project Summary was developed
by EPA's Industrial Environmental Re-
search Laboratory. Cincinnati, OH, to
announce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
The report is written particularly for
chemists and engineers working in the
oil shale industry. It summarizes the
current status of methods for the chemi-
cal analyses of oil shale effluents, and
hopefully provides a valuable reference
for those who must measure and control
the effects of oil shale waste products
on the environment. It is also recom-
mended for enforcement and regulatory
personnel, since neither emission limi-
tations nor control technology require-
ments can be established without ade-
quate measurement techniques.
The discussion includes spent and
raw shale, process waters of various
types, fuel gas produced by the retorting
process (retort gas), and burned fuel
gas. Methods are considered for the
measurement of trace and minor ele-
ments, dfssolved ions, organic com-
pounds, sulfur and nitrogen species of
environmental importance, and physical
properties such as dissolved solids.
The logic that prompted this effort is
centered on the fact that when analytical
methods developed for simple, homoge-
neous material are applied to complex
samples like oil shale effluents, extra-
ordinary interferences or matrix effects
can render the method ineffective.
Results using uncorrected methods are
usually erroneous and sometimes
meaningless. This report addresses that
question, and attempts to focus on the
applicability of chemical methods to the
analysis of oil shale effluents.
Results
The second chapter of the report
discusses the elemental analysis of oil
shale samples of all types with emphasis
on trace elements. The methods evalu-
ated for this task include neutron activa-
tion, analysis X-ray fluorescence, induc-
tively coupled plasma optical emissions
spectroscopy, traditional optical emission
spectroscopy, spark source mass spec-
troscopy and atomic absorption spec-
troscopy. All the methods describe the
applicability of that method to oil shale
samples and discuss important consid-
erations like detection limit, accuracy
and precision. The use of these methods
on oil shale samples are summarized in
table form in the text of the report.
Chapter Three of the report discusses
the analysis of wastewaters and leach-
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ates. Of the species and physical
characteristics discussed in the text,
methods for determining pH, conductivity,
F-, NH3, and NH4 have been shown tobe
adequate for a limited number of waste-
waters. Methods for Cl", total P, PO*",
total S, S03", SCN~, thiosulfate and
other reduced sulfur oxides, CN~, total
N, and total dissolved solids are not
confirmed. Methods for the latter species
either lack confirmation by an indepen-
dent method or have been shown to be
inaccurate or inappropriate.
Retort waters do not appear to pre-
sent special difficulties for the measure-
ment of pH. For example, Fox et al.
(1978) completed an interlaboratory
comparison of pH measurements with
three laboratories. They reported a
value of 8.65 ± 0.26, a variation typical
for the measurement of surface and
ground waters.
The measurement of electrical con-
ductivity, because it is so easily com-
pleted, often provides the most readily
available, though indirect, indication of
total salt concentration. To the plant
operator conductivity changes may pro-
vide the first clue of changing process
conditions; to the agronomist increases
in conductivity measurements serve a
quality assurance function, since the
conductivity of dilute solutions varies
linearly with ion concentration.
However, at the concentrations of
dissolved salts found in retort water
conductivity does not necessarily vary
linearly with concentration. This com-
plication can easily be avoided by diluting
retort waters up to 100x before mea-
suring the electrical conductivity
(Wildeman and Hoeffner, 1979). Another
advantage of this approach is that the
conductivity is then within the range of
most commercially available conductivity
cells.
Fluorine (F) has traditionally been a
difficult element to measure in complex
samples for several reasons. First, in-
strumental methods, for which inter-
ferences are commonly minimized or at
least understood, are only marginally
useful for F, or can be applied only with
unusual effort. This limits the analyst to
"wet" methods.
In 1978 Fox et al. completed an inter-
laboratory analysis of F in retort water
("omega-9" water). Considering the
complexity of the sample, the results
were encouraging. At an F level of 60
mg/l the interlaboratory coefficient of
variation was 16%, comparable to what
is normally observed with ground and
surface water (Staible, 1978). These
results included seven laboratories
using either the electrode or SPADNS
method. These data therefore suggest
that for omega-9 waters and other
comparatively dilute retort waters, the
ion selective electrode and SPADNS
method are viable techniques.
NH3 is typically one of the major
species in retort water and as such has
been determined frequently. Common
methods include (1) direct measurement
by ion selective electrode, (2) distillation
from a basic medium followed by titra-
tion with H2SO.t, and (3) automated
colorimetric procedures (Skougstad,
1979; EPA, 1979; APHA, 1976). For
example, Wildeman and Hoeffner (1979)
and Prien et al. (1977) both determined
t-NH3 in Paraho wastewaters using
method 2. Haas (1979) employed method
(1) for the analysis of TOSCO II retort
water. Wildeman's data suggested that
t-NH3 measurements were reproducible
within approximately ± 10%. The other
investigators reported no operational
problems such as irreproducible results
or drifting electrode potentials.
F-ox et al. (1978) compared three
methods for the analysis of omega-9
wastewaters: (1) basic distillation into
H3B03 followed by titration with H2SO4,
(2) basic distillation into H3B03followed
by the automated phenolate finish, and
(3) direct measurement by ion selective
electrode with no distillation. A total of
five analyses yielded an average of
3800 mg/l ± 10% RSD. This data sug-
gests that any of these methods are
adequate for retort water. Thus the
selection of a technique could be based
primarily on ease of application and
availability of equipment.
The analysis of the gases associated
with the retorting of oil shale is the
subject of Chapter 4.0.
Burned flue gases from oil shale
retorting should be similar in composi-
tion to utility and industrial sources
which are already widely monitored for
regulated pollutants such as S02 and
N0>. Existing monitors should therefore
be appropriate for this application.
However, methods for the analysis of
product (retort) gas have not been
widely investigated. The analysis of
retort gas is important from the gas
cleanup point of view, in that the gas
must be accurately characterized so
that the proper control technology can
be selected.
Hydrogen sulfide (H2S) and other
reduced forms of sulfur in the retort gas
have received some extra attention!
because, if oxidized to sulfur dioxide
(S02), they will become a regulated
emission and subject to control.
Most manual (i.e. "wet chemical")
methods for H2S are based on the
collection of sulfide as a stable precipi-
tate, followed by an analysis for sulfide.
One example is the EPA Method 11,
which is designated for compliance
monitoring of point sources. In this
method the sample stream is bubbled
through a suspension of Cd(OH)2 and is
thereby collected as CdS. The CdS is
dissolved and the sulfide is measured
with an iodometric titration (PEDCO,
1977).
Owens and McDonald (1979) employed
the EPA Method 11 for measuring H2S
during the in-situ sideburn at site 12 at
Rock Springs. They recommended adding
an empty impinger after the H202 im-
pinger in order to prevent carryover,
since they claimed that "prior experience
had shown that even minute amounts of
this screening solution could drastically
affect the outcome of this test".
There are numerous instrumental
methods for hydrogen sulfide, and many
of them are summarized in Table 1. The
drawback with instrumental methods
for H2 determinations in retort gases is
the excessive dilution required to main-
tain concentrations within the dynamic
range of the instrument.
Ammonia and other nitrogen contain-
ing gases are important in the retort gas
because of their commercial value and
their deleterious effects on certain
types of sulfur control equipment. In
addition, the presence of ammonia and
other nitrogen compounds in the retort
gas could increase the amount of oxides
of nitrogen (NO,) formed during com-
bustion. Many of the methods described
in the text are optimized for ambient or
near ambient levels of NH3 with the
corresponding emphasis on low detec-
tion limits and preservation of sample
integrity. However, when the sampling
and interference problems associated
with retort gas are properly accounted
for, it is likely that at least some of these
methods can be adapted.
The most common manual methods
begin by adsorbing NH3 in a dilute acid,
typically 0.1 n H2SO«, followed by a
variety of possible finishes. For example,
the NIOSH (1977) calls for the collection
of NH3 in 0.1 N H2S04, followed by the
potentiometric (i.e. ion selective elec-
trode) detection of the collected NH3.
Assuming a working range of 0.1-1000
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'able 1. Commercial Instruments for Measuring HaS and Related Species
Manufacturer/Model Range Principle
Comments
Sierra Labs
AID, Inc.
CEA Instruments. Inc.
Thermal Electron Corp.
InterScan Corp.
Energetic Science
Tracer Instruments
Wilks Scientific Corp.
E.I. DuPont
Bendix
Bendix
Meloy
0-50 ppm
>30ppb
0.003-10 ppm
0-5000 ppm
0.01-100 ppm
0-250 ppm
0-2%
0-1%forSOa
0-1 ppm
0.005-10.0 ppm
Solid slate sensor
GC/FPD
Automated wet chemical
Pulsed fluorescence after
conversion to SOz
Electrochemical cell-polarographic
Electrochemical cell-polarographic
GC/HECD
Dispersive IR Absorption (filters)
Non-dispersive UV Absorption
FPD
NDIR
FPD
For industrial hygiene
Also COS, SOa, mercaptans
Modules available for
several other gases
SOa and total S
Measures SOa, H2S, or total
with appropriate filters
Selectivity gained through
chemical filters
FPD: flame photometric detector
NDIR: non-dispersive infrared absorption
GC: gas chromatography
HECD: hall electrolytic detector
mg/ml for the ammonia electrode, a
solution volume of 10 ml, a sample flow
rate of 100 ml/min, and a sampling time
of 100 minutes leads to a working range
of 0.1-1000 mg/m3 in the gas sample,
adequate for retort gas, especially since
the absorbing solution can be diluted.
Major advantages of the ion selective
electrode (ISE) are ease of use and
relative freedom from interferences.
(The major interferences with the ISE
are volatile amines, whteh are insignifi-
cant compared to NH3 in retort gas.)
However, the membrane in the ammonia
is easily fouled by oils and tars, and this
feature remains a potential problem.
Coatter et al. (1978) did describe in
detail the sampling and analysis pro-
cedures which they used for NH3 at the
Paraho retort. They employed four
impingers in series cooled in an ice
bath. The first typically contained d.i.
HZ0, the second 5% HCI, the third was
empty to catch any spill-over, and the
last implnger contained silica gel to dry
the gas stream. Sampling rate was 200
ml/min. They reported that the analyti-
cal error in measuring the captured NH3
was much less than the total ammonia
concentration. No data was available on
the precision of the total sampling and
analysis scheme.
Quality assurance (QA) is of utmost
importance when dealing with analytical
methods for the chemical determination
of oil shale samples. QA has found its
way into the legal and management
aspects of oil shale as well as in the
traditional technical role. Emphasis and
technique may vary, but quality assur-
ance can be described and practiced in
terms of aware personnel, proper in-
strumentation, analytical methods,
quality control, record keeping and
management support.
Conclusions and
Recommendations
Of the methods discussed in the text,
some have been evaluated for oil shale
wastes and have been proven adequate;
others have been proven inadequate
and most have not yet been completely
tested. As the summaries in the follow-
ing paragraphs indicate, additional
evaluation and development of analyti-
cal methods is still required.
Trace Elements
The status of analytical methods for
trace elements in oil shale wastes is
similar to that of most other complex
samples. The total concentration of
essentially every element can be deter-
mined by the proper combination of
readily-available instrumental tech-
niques such as neutron activation, X-
ray fluorescence, spark source mass
spectroscopy, inductively coupled
plasma optical emission spectroscopy,
traditional optical emission spectroso-
copy, and atomic absorption spectros-
copy. As described in the text, for a
specific sample and set of elements a
combination of instrumental techniques
can be selected by comparing their
elemental coverage, accuracy, preci-
sion, and mode of operation.
Wastewaters
For a few parameters, methods de-
scribing the characteristics of pH, con-
ductivity, F~, NH3 and NH< have been
shown to be adequate for wastewaters
tested to date. Methods for other dis-
solved inorganics such as CI", PO/,
* US GOVERNMENT PRINTING OFFICE 1981-757-012/7209
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total P, S, SOV, SOs", SCN", S203~ and
other sulfur oxides need additional
confirmation.
Gases
The composition of gases derived
from the combustion of oil shale retort
products are similar to other industrial
and utility gases and established meth-
ods for monitoring these compounds
are presently thought to be acceptable.
Methods for the analysis of retort
gases have not been widely investigated,
and require additional development,
especially in the area of reduced sulfur
and nitrogen compounds.
Quality Assurance
Although the number of reference
standards available for oil shale analysis
are quite similar, quality assurance can
be practiced by management and ana-
lytical personnel working together.
-I
John R. Wallace is with the Charles H. Prien Center for Synthetic Fuel Studies.
Denver Research Institute, University of Denver. Denver. CO 80208.
Robert Thurnau is the EPA Project Officer (see below).
The complete report, entitled "The Analysis of Oil Shale Wastes: A Review,"
(Order No. PB 81-190 522; Cost: $21.50. subject to change) will be available
only from:
National Technical Information Service
5285 Port Royal Road
Springfield. VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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