- Nickel(II) carbonate (NiCO₃) is an inorganic compound composed of nickel in the +2 oxidation state and carbonate anions (CO₃²⁻). It appears as a pale green, odorless solid, typically encountered in its basic hydrated forms rather than as the pure, anhydrous compound.
- Nickel(II) carbonate is sparingly soluble in water but readily reacts with acids, releasing carbon dioxide gas and forming the corresponding nickel salt. This compound is of interest both in fundamental inorganic chemistry and in various industrial processes due to its role as a precursor to other nickel compounds.
- Structurally, NiCO₃ adopts a trigonal planar geometry around the nickel ion, with the carbonate ion coordinating through its oxygen atoms. In many commercial preparations, nickel carbonate exists as a basic carbonate, such as nickel(II) carbonate hydroxide [NiCO₃·Ni(OH)₂·xH₂O], which has a more complex and variable structure. The pure form can be synthesized by the precipitation reaction of a soluble nickel(II) salt, such as nickel sulfate (NiSO₄), with a soluble carbonate like sodium carbonate (Na₂CO₃), under controlled conditions to avoid formation of basic carbonates or hydroxides.
- Nickel(II) carbonate is widely used in the preparation of nickel-based catalysts and pigments, as well as in electroplating and ceramics. It is also employed as an intermediate in the production of nickel oxide (NiO) by calcination. Due to the potential release of toxic nickel ions, proper handling is essential. Exposure can lead to skin sensitization or respiratory issues, and nickel compounds are classified as carcinogenic in some jurisdictions. Hence, its industrial use is subject to regulatory controls to ensure safe handling and environmental protection.
- Environmentally, NiCO₃ can pose a risk due to the mobility of nickel ions in soil and water. In natural settings, it may form under specific geochemical conditions, particularly in nickel-rich ultramafic rocks. However, its natural occurrence is rare, and most commercially available material is synthesized. Research continues into the reactivity of nickel carbonate in environmental and biological systems, including its role in soil chemistry and potential effects on microbial activity.
