Properties and uses of nickel sulphate

Nickel sulphate is an inorganic compound with the chemical formula NiSO4, usually found in the form of a hexahydrate, NiSO4-6H2O.

Nickel sulphate is yellow to green crystalline, decomposes at 848°C, generating sulphur trioxide and nickel monoxide toxic fumes. Nickel sulfate is a kind of electroplating nickel and the main nickel salt of chemical nickel, which is widely used in electroplating industry, catalytic industry, pharmaceutical industry, inorganic industry, national defence industry and printing and dyeing industry, etc., and has high economic value.

Properties

When nickel sulphate is crystallised from solution, the crystallisation product is affected by temperature. In 30.7 ℃ precipitated green orthorhombic crystal system of nickel sulfate heptahydrate, in 30.7 ℃ - 53.8 ℃ precipitated blue-green tetragonal crystal system of α - nickel sulfate hexahydrate, 53.8 ℃ above the precipitation of green monoclinic crystal system of β - nickel sulfate hexahydrate, which will be in the room temperature phase change back to the blue-green and opaque. The commercial product is mostly α-hexahydrate.

Heating the hydrated salt results in the removal of water molecules, of which the tetrahydrate and monohydrate are stable, and the bright yellow anhydrous nickel sulphate has to be made above 330°C. It decomposes to oxidised nickel at about 800°C. It decomposes to nickel oxide and sulphur trioxide at about 800 °C. Crystallisation in higher concentrations of sulphuric acid also gives low hydrates which are slowly soluble in water.

Alkaline solutions of nickel sulphate convert carbon monoxide to nickel tetracarbony.

Preparation

From the reaction of metallic nickel with mixed sulfuric/nitric acid.

3Ni+8HNO3→3Ni(NO3)2+2NO↑+4H2O

Ni(NO3)2+H2SO4→NiSO4+2HNO3

Usage

In electroplating industry, it is used as the main raw material of electroplating nickel and chemical nickel. In printing and dyeing industry, it is used as the mordant of reducing dyes, and used in the production of phthalocyanine blue complexing agent. In the pharmaceutical industry, it is used as the catalyst for the oxidation step in the production of vitamin C. In addition, also used as other nickel salts such as nickel oxide, nickel ammonium sulfate, nickel carbonate raw materials, the production of hardened oil when the catalyst for hydrogenation of fats and oils, also used in the production of nickel-cadmium batteries and the production of cemented carbide. Using 10 volts of electricity, connected to a 0.5M aqueous nickel sulphate solution can be plated on a 2 * 5 (cm) copper sheet in just 10 minutes.