Precipitation of Heavy Metals

REMOTOX® is a calcium polysulfide based liquid consisting of multiple sulfur compounds that strongly bond to heavy metals in water. The metal sulfides formed have a very low solubility and persist as stable solids, which allows for a more environmentally sound disposal.

Application advantages:

  • High reactivity with heavy metal ions and extremely low solubility of resulting metal sulfides over a wide pH range.
  • Can break and precipitate chelated metals without pretreatment.
  • Removes chromates and dichromates without preliminary reduction of the chromium to its trivalent state.
  • Reduces mercury to low parts per billion.
  • Better settling and dewatering aspects of the metal precipitate.
  • Dissolved calcium ions form a coagulant/flocculant aid.
  • REMOTOX can be adapted to enhance any existing system.
  • Converts waste cyanides into the relatively non-toxic thiocyanate ion.

Product features:

  • Its residues are inert and non-toxic.
  • REMOTOX is relatively inexpensive.
  • It is not DOT regulated.
  • Unlike dithiocarbamate or its related salts, it does not contain or release carbon disulfide.
  • REMOTOX ions provide more stability in acidic medium as compared to other sulfides. It also presents a lower H2S exposure potential and it is noticeably less malodorous.

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.

For general application and dosage guidelines, samples or pricing information, please email us at or call us at 623-328-5175.

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