Nickel Sulfate

What is Nickel Sulphate?

  • Nickel sulphate or Nickel (II) sulphate is an inorganic compound. It is highly soluble in aqueous solutions.

  • This sulphate compound is a green coloured salt or ester of sulphuric acid. 

  • It is formed by replacing one or both of hydrogen atoms with Nickel (metal) atoms.

  • The chemical formula for Nickel Sulphate is NiSO4.

  • Nickel (II) Sulphate is available naturally in the form of mineral morenosite. It is usually unstable in the air.

  • It is also called,

  1. Nickel (II) Sulphate,

  2. Nickel monosulphate,

  3. Nickelous Sulphate.

  4. Nickel Sulphate hexahydrate.

  5. Nickel (2+) Sulphate.

  • Nickel Sulphate can be formed in laboratories by dissolving Nickel oxide in Sulphuric acid. The reaction gives a concentrated solution of Nickel Sulphate Heptahydrate. On heating the concentrated solution, crystalline Nickel Sulphate hexahydrate is derived for commercial use. 

  • It is a carcinogenic compound as exposure to its fumes can cause cancer. 

Physical Properties of NiSO4

  1. It occurs in yellow solid when in anhydrous form, green-blue crystals when in heptahydrate form and in blue crystals when in hexahydrate state.

  2. It is odourless. 

  3. Its molecular weight is 154.75 g/mol.

  4. It is having a density of 3.68 g/cm3 

  5. Its boiling point is 840 °C

  6. Its Melting point is > 100 °C in anhydrous state and >53 °C for hexahydrate form.

  7. The linear chemical formula is given as NiSO4(H2O)6.                 

  8. It is soluble in water and methanol. Solubility in water is 293 g/L at 0°C. 

  9. Its CAS registration number is 7786-81-4.

  10. Though it has a sweet, astringent taste, it is recommended not to taste.

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Chemical Properties of NiSO4

  1. It is non-flammable.

  2. It is insoluble in alcohol and ether.

  3. It is not compatible with strong acids.

  4. After dissolving in water, it forms an acidic corrosive solution. On corrosion, it emits fumes of oxides of sulphur.

  5. When it is dissolved in water, and the solution is heated to decompose, liberates fumes of nitrous oxide. Fumes of Nickel Sulphate are highly toxic.

  6. As its aqueous solution is acidic, the pH value is 4.5. 

  7. On heating at 103°C, aqueous Nickel Sulphate loses the water molecules. And heating up to 848°C, the anhydrous form decomposes to form sulphur trioxide and nickel oxide. The chemical expression is  

  8. NiSO4 → NiO + SO3 

  9. Nickel Sulphate gives double by-products of salts on reacting with alkali metals or ammonium sulphates. These sulphates are isomorphous.

  10. Reacting with hydrochloric acid gives Sulphuric acid and Nickel Chloride. The chemical reaction is as shown,

NiSO4 + HCl → NiCl + HSO4

While reacting with sodium hydroxide, it forms Sodium Sulphate and Nickel hydroxide. The chemical equation is 

NiSO4 + NaOH → Ni(OH)2 + Na2SO4

Production of Nickel Sulphate

The Nickel Sulphate is usually prepared by dissolving nickel oxide into hot, dilute Sulphuric acid. The general steps involved in the process are,

  • The metal, Nickel, is supplied in an enclosed reactor along with Sulphuric acid solution.

  • Oxygen is introduced into the reactor.

  • During this process, temperature and pressure in the reactor are kept constant.

  • In an enclosed environment, the chemical process (oxidation) gives rise to concentrated Nickel Sulphate solution.

  • On further heating and increasing the pressure in the reactor, blue crystalline Nickel Sulphate is formed.

  • By treating the crystals with a diluted solution of Barium carbonate, elimination of impurities takes place.

  • This process is widely used for mass production of Nickel Sulphate.

Uses of Nickel Sulphate

Nickel Sulphate is widely used 

  1. As the electrolyte for surface finishing processes of metals such as metal plating and electrorefining.

  2. In the preparations of many Nickel catalysts and compounds. 

  3. As a reducing agent for flashing on steel surfaces, imparting Nickel coating from the surface.

  4. For blackening Brass and Zinc.

  5. As a mordant in dyeing and printing metals, textiles and ceramics.

  6. As a coating for many metals.

  7. In the production of driers that are used in protective shields.

  8. They are occasionally used as calibrant to measure magnetic susceptibility. 

Effects of NiSO4 on Human Health

Nickel Sulphate can be assimilated in the human body by inhalation or ingestion. Once it is absorbed in the body, it concentrates in the lungs, gut, kidneys and liver. Exposure to NiSO4 causes,

  1. Skin irritations

  2. Giddiness

  3. Lassitude

  4. Headache

  5. Myalgia

  6. Gastrointestinal effects such as abdominal pain, nausea, vomiting, diarrhoea

  7. Hemorrhagic gastritis

  8. Transient hyperbilirubinemia and albuminuria

  9. Bronchial asthma

  10. Dyspnoea

  11. Mild cyanosis

  12. Chronic obstructive airways syndrome

  13. Chronic urticaria

  14. Dermatitis

FAQ (Frequently Asked Questions)

1. What Are The Safety And Packaging Specifications While Handling NiSO4?

While treating Nickel Sulphate, toxic fumes and heat are generated. It has hazardous effects on health. To avoid its adverse effects on health, it should be handled, packed and shipped cautiously. Following are the Safety measures while handling NiSO4,

  • Proper training should be given before handling NiSO4

  • The area where treatment, storage of NiSO4 is going to take place should be marked and isolated from other activities.

  • As it is not compatible with oxidising agents, it should not be treated or kept near them.

  • Use masks, gloves, goggles and aprons while handling NiSO4

  • In case containers catch fire, use a fire extinguisher and use water sprays to keep them cool.

For storage and shipping of Nickel Sulphate cold, tightly closed, made up of antioxidant material containers should be used.  

2. How To Dispose Of Nickel Sulphate Waste?

As Nickel Sulphate is a carcinogenic compound, it can not be disposed of in water drains. Following methods are used to dispose of,

  1. It can be destroyed by introducing into the strong solution of sodium dichromate and sulphuric acid. It takes one to two days to destroy Nickel Sulphate completely. The residue is later flushed with a large amount of water to the sewer. 

  2. Another method to destroy it is by reacting it with nucleophiles such as ammonia, thiosulphate and hydroxyl ions. Dissolving Nickel Sulphate in ethanol before the treatment accelerates the process.

  3. By adding a saturated solution of potassium permanganate with acetone destroys Nickel Sulphate.

  4. Potassium hydroxide dissolved in methanol destroys NiSO4

  5. By using sodium dichromate and sulphuric acid solution, Nickel Sulphate is decomposed. Further, the waste is disposed of in a large water body.