REMOTOX® precipitates highly soluble metals as less soluble, less toxic metal sulfides. In the case of chromium, the metals precipitates as a hydroxide.
Effective against a wide range of heavy metals, chlorinated compounds, and other contaminants. See bench test results on Metal Removal from Groundwater Contaminated by Zinc Smelter.
Converts hexavalent and trivalent chromium to chromium hydroxide in a one-step reaction. See Overall Effectiveness of Water Treatment Process for Cr(III) and Cr(VI) and Summary of Studies on Cr(VI) Reduction by Calcium Polysulfide.
Delivers more stability in subsurface environments than other reductants, such as sodium dithionite. See In-Situ Remediation of a Chromium-Contaminated Site Using Calcium Polysulfide.
Has proven to provide greater persistence and lateral transport away from injection wells because of its slower reaction rates.
May be applied to in-situ and ex-situ media.
The US EPA has identified Calcium Polysulfide as a reagent suitable for use in in-situ chemical reduction (ISCR), stabilization and solidification of multiple contaminants. Several abstracts and studies are available through CLU-IN Technologies, the Hazardous Waste Clean-Up Information website, sponsored by the US EPA.
Bench scale evaluation, case studies and dosage guidelines on Calcium Polysulfide for the remediation of hexavalent chromium can also be found in the Chromium (VI) Handbook, available for purchase at Amazon.com or at Routledge.com.
REMOTOX®, a Calcium Polysulfide Solution, has proven to be effective under various site conditions. In in-situ remediation of soil and groundwater, it has shown to be more stable and persistent than other reductants in subsurface environments.
Over the past 40 years, this versatile multivalent ion sulfur chemistry has been well studied and successfully applied for the environmental remediation of heavy metals and other contaminants.
Calcium Polysulfide is fairly safe to handle out in the field. It is a non-toxic remedial amendment that oxidizes under aerobic conditions to form calcium, elemental sulfur and sulfate. When introduced into the environment, Calcium Polysulfide breaks down to form bisulfide, aqueous hydrogen sulfide and other sulfur compounds. Heavy metal ions are precipitated as less soluble, less toxic metal sulfides by these breakdown products. Metal hydroxides change solubility with changes in pH, whereas metal sulfides remain insoluble within a wide pH range. See Solubility of Metal Hydroxides and Sulfides as a Function of pH.
While effective treatment by Calcium Polysulfide can be achieved over a wide pH range, best results are typically obtained within pH 7-10. Adjustments to the pH of the treatment system can enhance the metal precipitation process. See pH Guidelines for Treatment of Soluble Metal Streams.
