|Stabilization and Testing of Mercury Containing Wastes: Borden Catalyst (PDF) (42 pp, 3.89 MB) (EPA/600/R-02/019) September 2001
This report was submitted by the University of Cincinnati (UC) in fulfillment of Contract No. 68-C7-0057 under the sponsorship of EPA. This report covers June 1999 through July 2000; laboratory work was completed in July 2000. This report evaluates the chemical stability of spent mercuric chloride catalyst in an aqueous environment before and after treatment with stabilizing agents. The stabilizing agents evaluated in this study are sulfide and phosphate.
Samples obtained by UC and EPA personnel at the Borden Chemicals and Plastics plant on June 10, 1999, were characterized for total mercury content, pH, and acidity prior to performing the leaching tests on untreated waste. Leaching tests and analytical work performed by UC and their contract laboratories included the toxicity characteristic leaching procedure, solid stability in water, and leaching at constant and variable pH values.
After completing the baseline tests on untreated waste, the spent mercuric chloride catalyst was treated with sulfide and phosphate binders to evaluate the effectiveness of these additives on reducing the concentration of mercury in the leachate. The mercuric chloride waste was crushed and combined with the binders at various molar ratios and pH ranges prior to performing the identical leaching tests noted above.
Measured mercury concentrations in the generated leachates indicate that sulfide treatment lowers the aqueous mercury concentration, while phosphate treatment has little effect on decreasing the mercury concentration. Analytical results for individual leaching methods carried out over a pH range of 2 to 12 do not define a consistent trend for mercury concentrations as a function of pH. However, samples treated with moderate to large amounts of sulfide (i.e., a sulphur/mercury molar ratio greater than 3) released less mercury.
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