Calcium Polysulfide Remotox
A proven in situ chemical reduction technology for treating hexavalent chromium and other oxidized metals in soil and groundwater — reliably converting them to less toxic, less mobile forms.
What is Remotox?
Remotox is Hepure’s calcium polysulfide (CaSₓ) product — an aqueous reducing agent specifically designed for in situ treatment of hexavalent chromium (Cr⁶⁺) and other oxidized heavy metals in soil and groundwater.
When injected into the subsurface, calcium polysulfide creates strongly reducing conditions that convert toxic hexavalent chromium to the much less toxic and far less mobile trivalent chromium (Cr³⁺). The trivalent chromium then precipitates as chromium hydroxide (Cr(OH)₃), effectively immobilizing it in the soil matrix.
Remotox has been successfully applied at industrial sites, former plating operations, and chromite ore processing residue (COPR) sites across the United States. It offers a cost-effective alternative to excavation-based remediation approaches and is well-suited for both source area treatment and plume management.
Remotox CaSₓ technical details
A concentrated aqueous calcium polysulfide solution ready for direct injection or dilution, depending on site requirements.
Remotox Calcium Polysulfide
Aqueous Reducing AgentContact Hepure for product specifications and dosing guidance tailored to your site conditions. Our team can evaluate your site data and recommend the optimal application approach.
The reduction chemistry
Calcium polysulfide provides a powerful, sustained source of reduced sulfur species that chemically reduce Cr⁶⁺ to Cr³⁺.
Electron Transfer
Polysulfide ions (Sₓ²⁻) donate electrons to Cr⁶⁺, reducing it to Cr³⁺. This changes chromium from a highly soluble, carcinogenic form to a low-solubility, low-toxicity precipitate.
Precipitation
Trivalent chromium precipitates as Cr(OH)₃ — a stable, insoluble solid that remains immobilized in the soil matrix under normal environmental conditions.
Sustained Reduction
Excess polysulfide creates a reducing buffer zone in the subsurface that continues to treat chromium migrating into the treated area, providing long-term protection.
Where Remotox excels
Calcium polysulfide is effective across a range of site conditions and delivery methods.
Source Area Injection
Direct injection into Cr⁶⁺ source zones via direct-push or injection wells to rapidly reduce contaminant concentrations at the point of highest mass.
Reactive Barrier
Injection along a transect downgradient of the source area to create a permeable reactive zone that treats the chromium plume as groundwater flows through.
Soil Mixing
Application via large-diameter auger mixing for shallow soil treatment — particularly effective at COPR sites and areas with heterogeneous chromium distribution.
Recirculation Systems
Extraction-injection recirculation to distribute CaSₓ through the aquifer over larger areas, maximizing contact with dissolved chromium in the plume.
Beyond chromium
While chromium reduction is the primary application, calcium polysulfide’s reducing chemistry is also effective against several other oxidized metals.