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- ------- 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 ------- '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 ------- 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 Postage and Fees Paid Environmental Protection Agency EPA 335 Official Business Penalty for Private Use $300 RETURN POSTAGE GUARANTEED 0000329 ------- |