Graus Chemicals, LLC

- In-Situ Remediation of Heavy Metal Contaminated Soils

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Lead, chromium, zinc, copper, cadmium, mercury, and arsenic are among the most common metal contaminants found on remediation project sites. REMOTOX (calcium polysulfide) has proven to be highly effective in the solidification/ stabilization of heavy metal-contaminated soils and groundwater. Engineers also found it to be more stable and persistent in subsurface environments than other reductants such as sodium dithionite, does not form nearly as much insoluble precipitate as ferrous sulfate, and is relatively safe to handle in the field. Calcium Polysulfide is a non-toxic reagent that oxidizes under aerobic conditions to form calcium, sulfate and elemental sulfur.

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  • Assay (wt. % CaSx): 29
  • Specific Gravity (g/cc): 1.27
  • Specific Gravity (lbs/gal): 10.6
  • pH: 11.5
  • Color: Ruby-red
  • Odor: Moderate sulfide (slight rotten eggs)

REMOTOX is not regulated by the US Department of Transportation. The vapor space over the solution is mainly water vapor. It is considered stable in storage and transportation.

REMOTOX is available in 5 gal plastic pails, 55 gal plastic drums, 265 gal plastic non-returnable totes and in bulk tanker loads. Materials of construction suitable for storing include stainless steel, fiberglass, polypropylene, polyethylene. If properly stored, our product has a shelf life of minimum one (1) year.

Personnel handling REMOTOX should wear Personnel Protective Equipment (PPE) to avoid exposure to the skin or eyes. Use REMOTOX in well ventilated area, and wash thoroughly after handling.

REMOTOX (calcium polysulfide solution) has proven to be highly effective in the remediation of heavy metals-contaminated soils and groundwater. Engineers also found it to be more stable and persistent in subsurface environments than other reductants such as sodium dithionite, does not form nearly as much insoluble precipitate as ferrous sulfate, and is comparatively safe to store and handle in the field. It is a non-toxic reagent that oxidizes under aerobic conditions to form calcium and sulfate.

Since the 1980s, calcium polysulfide has become increasingly popular as a cost-effective reducing agent in the treatment of hexavalent chromium (VI).Hexavalent chromium in the form of chromate is reduced to the insoluble form of trivalent chromium (Cr III), which is less toxic and tends to fall out of solution and adhere to soil.

Bench tests, case studies and dosage guidelines regarding chromium remediation by calcium polysulfide can be found in the Chromium (VI) Handbook. Book review and purchasing information available at Amazon.com or at CRC Press.

Calcium polysulfide is well-recognized and approved by regulatory agencies for environmental and agricultural applications. The US EPA (US Environmental Protection Agency) has identified calcium polysulfide as a chemical suitable for use in In-Situ Chemical Reduction of multiple toxic substances. Several abstracts and studies are available through the Hazardous Waste Clean-Up Information (CLU-IN) website sponsored by the US EPA. Furthermore, the NSF (National Sanitation Foundation) has approved its use in groundwater treatment. And the USDA (United States Department of Agriculture) has approved its use in diverse agricultural applications.

REMOTOX is our registered trade name for calcium polysulfide solution, also commonly referred to as lime sulfur solution. It is a strong, water-based precipitant and reductant consisting of multiple sulfur compounds, with the following properties.

  • Remotox (Calcium Polysulfide Solution) decomposes in water when air or carbon dioxide are introduced, generating aqueous hydrogen sulfide, thiosulfate and colloidal sulfur.
  • Heavy metal ions are precipitated as metal sulfides by thiosulfate breakdown products and aqueous hydrogen sulfide. If excess hydrogen sulfide is produced it is recycled into the system for efficient precipitation.
  • Hexavalent chromium is reduced to trivalent chromium, which is then precipitated as chromium hydroxide.

  • Remotox reacts with cyanide in wastewater treatment, a moderately exothermal reaction, to produce thiocyanate, which can then be discharged to a municipal wastewater system.
  • As thiocyanate is corrosive in higher concentrations, especially when hot, it may be necessary to decompose it by adding lime. The reaction produces calcium carbonate, gypsum and ammonia, which typically present no disposal problems.

The successful use of Remotox depends on a few points which must be considered. Be sure each of the following items are observed when bench testing for treatment:

  1. Remotox must be decomposed into its reactive products by aeration or carbon dioxide.
  2. Allow sufficient time for completion of sulfide formation through flow rate and/or tank size.
  3. While chromium treatment does not require decomposition, aeration speeds the reaction.

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Remotox is readily available in 55-gallon drums, 265-gallon totes, and in tank truck quantities.

Product is not DOT regulated. Compatible materials of construction for storing and handling Remotox at ambient temperature (up to 120ºF) include stainless steel, fiber glass, polypropylene, polyethylene.

Store containers out of direct sunlight. Avoid contact with acids or acidic materials, due to H2S evolution. Handle Remotox in enclosed containers to avoid breathing product vapors. Avoid contact with skin and eyes. Use in a well-ventilated area. Wash thoroughly after handling.

Please refer to the Safety Data Sheet for the most current Safety and Handling information.

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