Cobalt hydroxide chemical formula Co(OH)2. It is a rose-red monoclinic or tetragonal crystal, insoluble in water, slightly amphoteric, insoluble in strong alkali, but soluble in acid and ammonium salt solution. The melting point is 1100-1200 C , which is amphoteric hydroxide.
Cobalt hydroxide has the following production methods:
1. The purified chloride solution is purified by hydrogen peroxide and iron is removed by adding sodium carbonate or ammonia water when necessary to ensure complete purification. The purified cobalt chloride is purified by nitric acid and hydrochloric acid. Solution is added to NaOH to produce cobalt hydroxide, which is then washed and centrifuged to produce cobalt hydroxide products. Its Co+2HCl=CoCl2+H2_, CoCl2+2NaOH=Co(OH)2_+2NaCl
2. Electrolysis: The solution of salt is obtained by electrolysing cobalt as anode.
3. The sulfate or nitrate of cobalt divalent reacts with alkali to form cobalt hydroxide. A nearly saturated solution was formed by dissolving 100g CoSO4.7H_2O in water. Alkali solution formed by dissolving 42g sodium hydroxide in 60mL water was added under heating and stirring conditions The precipitation reaction is carried out in a long beaker, which is conducive to the clarification of the mixture. The precipitation formed at the beginning is blue. When heated in a water bath, the precipitation rapidly turns red. After clarification, it is washed Several times by water precipitation, then filtered on the Brinell funnel, and washed with water until the washing water is neutral. Finally, it is dried in a vacuum dryer with concentrated H2SO4. Because cobalt hydroxide will be oxidized slowly in air, the preparation operation Is best carried out in an inert gas protected operating box.
4. Reaction of cobalt metal with dilute nitric acid at 60-70 C. When the reaction basically stops, the water lost is replaced, and the surplus metal is separated. The solution is nearly neutral by adding CoCO3. At this temperature, the solution Is kept warm for time 2-3 hours, and the insoluble matter is removed by filtration. Then slowly add 2% ammonia water under the condition of continuous stirring and heating, so that the blue precipitation can be transformed into purple in time, and then into Pale rose-red precipitation. After the reaction is completed and clarified, the solution is sucked out by a straw and washed with water until the solution is neutral. The precipitation is quickly filtered out and dried in a vacuum dryer with concentrated H2SO4.