Nickel in water is generally reported as dissolved or total nickel, not as a single intact salt. Nickel salts dissolve to nickel ions and counter-ions; the forms actually present depend on pH, redox conditions, chloride, sulfate, carbonate, organic ligands and other constituents.
How to read this page: The salts below are common reagents, products or process chemicals associated with water-bearing streams. Their listing does not mean that each salt occurs in natural water. Routine analyses quantify nickel and usually do not identify the original salt or source.
Common nickel salts and compounds in water-related streams
| Salt or nickel form | Formula / description | Typical application / industry / where used | Typical aqueous streams where encountered |
|---|---|---|---|
| Nickel sulfate | NiSO4, commonly supplied as a hydrate such as NiSO4·6H2O | Electroplating, electroless nickel plating, battery-material manufacture and nickel-chemical production. | Spent plating baths, rinse waters, bath-dragout, process liquors and wastewater from nickel finishing or chemical manufacture. |
| Nickel chloride | NiCl2, often supplied as NiCl2·6H2O | Electroplating and electroless plating; precursor for other nickel compounds. | Plating baths and rinses, metal-finishing wastewater and process water from nickel-compound production or use. |
| Nickel nitrate | Ni(NO3)2, commonly hydrated | Specialty nickel-compound manufacture, catalysts and laboratory or industrial process use. | Manufacturing solutions, rinse waters and wastewater where nickel nitrate is used. It is not a typical salt naturally identified in routine water analyses. |
| Nickel acetate | Ni(CH3COO)2, often supplied as a hydrate | Specialty chemical production, catalysts, textile and surface-treatment applications. | Process solutions and wash waters associated with nickel acetate manufacture or use. |
| Dissolved nickel in natural or impacted water | Primarily Ni2+ with counter-ions and sometimes complexes; the analysis may be reported as dissolved or total Ni. | Weathering of nickel-bearing minerals and human activities such as metal processing, alloy production and electroplating. | Groundwater and surface water, mine drainage, industrial discharges and water affected by corrosion or metal finishing. Speciation depends on the water chemistry. |
| Nickel carbonate and basic nickel carbonate | NiCO3 is sparingly soluble; commercial “basic nickel carbonate” is a family of hydrated, composition-variable materials. | Intermediate in nickel chemical production, catalysts and ceramic or pigment manufacture. | Slurries, solids and process waters from nickel-compound manufacture or use. In acidic water, carbonate solids may dissolve; do not treat the commercial material as a single defined dissolved salt. |
| Nickel hydroxide | Ni(OH)2; a sparingly soluble solid rather than a dissolved salt. | Precipitate formed during alkaline treatment of nickel-bearing water; also used in battery materials. | Metal-treatment sludge, precipitates and battery-manufacturing process streams. Its formation and residual dissolved nickel depend on pH, complexants and other ions. |
Nickel removal and treatment options
The suitable process depends on nickel concentration and speciation, pH, complexing agents, competing metals, salinity, flow and the required treated-water quality or recovery objective. Assess the complete water matrix and residuals rather than choosing a process from the salt name alone.
| Water-treatment challenge | Potential approach | Important design considerations |
|---|---|---|
| Dissolved Ni(II) in metal-finishing or industrial wastewater | Hydroxide or carbonate precipitation followed by clarification and filtration. | Final dissolved nickel depends on pH, reagent dose, competing ions and complexants. Sludge handling and any local discharge limit must be considered; testing can establish achievable performance. |
| Nickel recovery from a relatively concentrated, suitable stream | Selective ion exchange or other recovery process may be assessed. | Competing ions and complexants affect selectivity and capacity. Evaluate regeneration or eluate handling and whether recovered material meets the intended reuse specification. |
| Nickel with high total dissolved solids or strict product-water targets | Reverse osmosis or nanofiltration may be considered, often with pretreatment. | Membranes transfer nickel to a concentrate rather than destroy it. Assess scaling, fouling, recovery and concentrate management for the specific feed. |
| Fine precipitates, colloids or nickel associated with suspended solids | Coagulation/flocculation and solid-liquid separation, with filtration where needed. | Nickel removal depends on whether it is dissolved, adsorbed or particle-bound; verify dissolved and total residuals and manage treatment sludge. |
For background on nickel in water and general treatment, see Nickel in water and Lenntech’s pages on coagulation and flocculation, ion exchange and reverse osmosis.
Discuss a nickel-bearing water or process stream
Share the available analysis, flow, operating conditions and treatment objective. These details help determine whether precipitation, selective recovery, membrane treatment or a combined process should be assessed.
Discuss a water-treatment challenge
To discuss a specific nickel-bearing water or process stream, contact Lenntech at info@lenntech.com.
Last reviewed: 7 November 2026 by Lenntech.
Sources and further reading
- World Health Organization: Nickel chemical fact sheet in the Guidelines for Drinking-water Quality.
- European Union: Drinking Water Directive (EU) 2020/2184.
- UK Health Security Agency: Nickel — general information and environmental occurrence.
- U.S. EPA: Electroplating pretreatment document — nickel salts in plating baths.
- U.S. EPA: Guidance on treatment of nickel in industrial wastewater.