Leaching test method

IN Allowable Concentration Using Leaching Test Method Class IV 0.2 mg/L Class III 2 mg/L Class II 5 mg/L... 

Mendel, J. E., "A Review of Leaching Test Methods and Leachability of Various Solid Media Containing Radioactive Wastes," Battelle Northwest Laboratory, Rept. BNWL-1765, (1973). 

The classical leach test methods currently in use, (the Soxhlet, Paige, Kelley, procedures described above in Description of Leach Rate Measurement Procedures as well as those described in... 

US-EPA provides two leaching test methods. One is the Toxicity Characteristic Leaching Procedure (EPA SW 846 Method 1311), and is called the TCLP for short. The other is the Synthetic Precipitation Leaching procedure (EPA SW—846 Method 1312), and is called the SPLP. The TCLP is intended to simulate dissolution of waste materials inside a landfill, and is the only leaching test specified by the regulation for characterization of the hazardous waste (40 CFR 261.24 Toxicity Characteristic, waste code D004-D043) under the Resource Conservation and Recovery Act (RCRA). 

Several kinds of leaching test methods are provided in the Netherlands from the viewpoint that the single batch leaching test shows one side of the elution behavior of the waste. Because the behavior of elution for powdery samples is different from those for a molded body, the leaching tests are different depending on the form of each sample. In addition, three kinds of test methods for the powdery waste are prepared to investigate the time dependency of dissolution behavior, as listed in Table 4. 

However, given that other, supposedly stable and leach-resistant catalysts that we had previously studied seemed to operate solely by a leaching mechanism, with no supported Pd apparently active for the reaction (vide supra) and that other authors had found precatalysts of this type to operate by solely a leaching mechaiusm in Heck conversions of aryl iodides (19), we decided to investigate this system further using the solid poison testing method. 

Gainesville, FL with individual fractions of three individual petroleum products at 24-25 °C for 24 h. The aqueous phase was analyzed for organic compounds via U.S. EPA approved test method 625. Average 2,4-dimethylphenol concentrations reported in water-soluble fractions of unleaded gasoline, kerosene, and diesel fuel were 50, 99, and 108 pg/L, respectively. 2,4-Dichlorophenol may also enter groundwater by leaching from coal tar, asphalt runoff, plastics, and pesticides (quoted, Verschueren, 1983). 

One of the more important factors affecting the isolation of radioactive waste is the rate of release of the radioactivity from the solid waste form to the environment. The most probable mechanism for release and transport of radioactivity from a solid waste form is by leaching of radioactive isotopes with groundwater. The objective of leach-testing various waste forms is to evaluate the rate at which specific hazardous radionuclides migrate from waste if and when the waste form comes in contact with groundwater. In this paper, measurement of leach rates of radioactive waste by a method which incorporates neutron activation is described. 

The basic technique established for leach testing involves exposure of a solid sample of known composition and having a premeasured surface area to a leaching medium for a fixed time interval. This is followed by analysis of the leaching medium for the mass of a specific material which has dissolved in the leaching medium. Difficulties arise in trying to duplicate in the laboratory the leaching medium and conditions present in the natural environment. The physical conditions under which the measurements are made differ widely for the various methods. 

A standard method for leach-testing immobilized radioactive waste solids and for reporting results has been proposed(10). 

Other workers, however, consider this proposed method of testing unduly tedious and offer constructive suggestions for accelerating leach tests ( ). Many of these proposed methods involve physical destruction of the waste form in order to increase the surface area exposed to the leachant. Such a procedure not only can alter the physical characteristics of the surface exposed to leaching but also can require the measurement of the surface areas of finely divided solids with the concomitant difficulties mentioned above. 

Leach rates for elements other than those listed in Table II can also be determined by this method. In fact, any element in the periodic table that is solid at room temperature and has an activation product with a half-life sufficiently long to allow leach testing can be studied with this technique. This method can also be applied to the study of the leach rates of alpha emitting actinides present in waste. In this case, standard carrier-free radiochemical procedures, coupled with low background alpha counting, would be invoked. 

The solidified SSM sample at the optimum reagent ratio was tested for metal leachability by the Toxic Characteristic Leaching Procedure as per 51 FR 21685-21693.(7) The target metals were analyzed by atomic absorption spectrometer using USEPA SW-846 "Test Methods for Evaluating Solid Wastes," 1986(8) as required by 40 CFR Part 261.( ... 

A test method for the batch extraction of treated or untreated solid waste or sludge, or solidified waste, to provide an indication of the leaching potential (ASTM D-5233) is also available. The goal of this test method is to provide an extract for measurement of the concentration of various analytes and therefore may be applied to a study of the smaller molecules that reside within the coal matrix. This test method, as written, is intended to provide an extract suitable for measurement of the concentration of analytes that will not volatilize under the conditions of the test method and may appear to offer limitations on the use of coal, but the test method does describe a procedure for performing a batch extraction of a solid. Again, the sampling and handling requirements that may be associated with the analysis of coal should also be applied to the method. 

As stated by Sahuquillo et al. (2003), there is an increased use of widely different leaching tests. Again, selection of appropriate and cost-effective methods used to assess environmental impact must provide a basis for long-term prediction of hazard and ecocompatibility. 

ASTM F 1534 Standard Test Method for Determining Changes in Fire-Test-Response Characteristics of Cushioning Materials after Water Leaching... 

American Society for Testing of Materials, Standard test method for static leaching of monolithic waste forms for disposal of radioactive waste, ASTM C 1220-98, 1998. 

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