Chromium, zinc, copper, lead, cadmium, mercury, and arsenic are among the most common metal contaminants found on remediation project sites. REMOTOX® (Calcium Polysulfide Solution), which is water soluble, precipitates the highly soluble metals as less soluble and non-toxic sulfides.
The US EPA has identified calcium polysulfide as a reagent suitable for use in in-situ chemical reduction, stabilization and solidification of multiple contaminants. Several abstracts and studies are available through CLU-IN, the Hazardous Waste Clean-Up Information website, sponsored by the US EPA.
Bench scale evaluation and case studies on in-situ Cr(VI) remedial methods, using calcium polysulfide, can also be found in the Chromium (VI) Handbook. Book purchasing information available at CRC Press Online or at Amazon.com.
*Quick Links to Case Studies:
Calcium Polysulfide is relatively safe to handle in the field, Numerous applications, especially for Cr(VI), have been successfully conducted at industrial sites, domestically and abroad, over the past 30 years. It is also widely used in agricultural applications to fruit trees, berries and as a soil conditioner.
When mixed with water, Calcium Polysulfide dissociates to form bisulfide, aqueous hydrogen sulfide and other sulfur compounds, Heavy metal ions are precipitated as metal sulfides by these breakdown products. Metal sulfides are far less soluble than metal hydroxides. Metal hydroxides change solubility with changes in pH. Metal sulfides remain insoluble within a wide pH range. See Solubility of Metal Hydroxides and Sulfides as a Function of pH. While effective treatment can be achieved over a wide pH range, best results are typically obtained within pH 7-10. Adjustments to pH of the treatment liquids can enhance the metal precipitation process. See Treatment of Soluble Metal Streams by Calcium Polysulfide.
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