Common mercury salts and compounds in water
Mercury salts must be distinguished from elemental mercury and organic mercury compounds. Their different solubilities and reactions affect transport and treatment. A dissolved-mercury result alone may miss mercury carried by particles.
See also mercury in water and the mercury element page.
Selected salts and compounds
This is a practical selection, not a ranking of abundance in every water. Qualitative solubility descriptions refer to the stated compound; hydration, temperature, pH and complexation can change its behaviour. A soluble starting salt does not necessarily remain unchanged after addition to water.
| Compound | Formula or form | Behaviour in water | Practical relevance |
|---|---|---|---|
| Mercury(II) chloride | HgCl2 | Soluble; the ILO/WHO card reports 69 g/L at 20 °C. | A soluble inorganic mercury source; chloride complexation affects aqueous behaviour. |
| Mercury(I) chloride | Hg2Cl2 | Very low water solubility. | A different oxidation state and compound from mercury(II) chloride. |
| Mercury(II) nitrate | Hg(NO3)2 · variable hydration | Dissolves with hydrolysis depending on acidity. | The starting nitrate salt does not fully specify the mercury species in the treated water. |
| Mercury(II) sulfide | HgS | Very low water solubility. | Relevant to mercury-bearing minerals and precipitation products; long-term stability depends on conditions. |
Removal, purification and recovery
Characterise total and dissolved mercury and identify whether elemental or organic forms are relevant. Precipitation/co-precipitation, suitable adsorbents and membrane separation are options for inorganic mercury, with selection dependent on concentration, ligands and other contaminants. Sulfur-containing sorbents may be considered for polishing after appropriate evaluation.
Solids separation is essential after precipitation. A low-solubility precipitate does not mean mercury has been destroyed: it remains in sludge, media or concentrate. Avoid assuming that treatment for inorganic salts also controls methylmercury or elemental mercury. Design residual handling and monitoring alongside the water-treatment process.
Information for process selection
Useful inputs include flow, pH, temperature, salinity, total and dissolved mercury, other metals, suspended solids and known complexing constituents. Define the treated-water target and whether recovery is an objective. Laboratory or pilot testing can establish performance for the actual feed rather than a simplified salt solution.
Discuss your water-treatment application
Contact Lenntech at info@lenntech.com to discuss your water composition and treatment objective.