Cobalt hydroxide, chemical formula Co(OH)2. It is a rose red monoclinic or tetragonal crystal, insoluble in water, slightly amphoteric, difficult to dissolve in strong alkali, but soluble in acid and ammonium salt solution. The density is about 3.6 g/cm3. The melting point of 1100-1200 ° C is an amphoteric hydroxide. Mainly used as a coloring agent for glass and enamel, as a raw material for other cobalt compounds, and as a desiccant for varnishes and coatings.
There are two crystal phases of cobalt hydroxide:
a-Co(OH)2 has a hydrotalcite-like structure, and is typically characterized by a layered bishydroxy-complex metal oxide structure. Because of its large layered structure, its conductivity is good. Blue cyan. However, this phase is not stable, is in metastable state, and is easily converted to the β phase.
β-Co(OH)2 has a brucite structure, hexagonal packing of hydroxyl ions is closely packed, and cations are filled in all octahedral spaces between adjacent two hydroxyl ions; a structural layer constituting a coordination octahedron. The structural layer is an ionic bond, and the structural layers are phase-dimensional. Its color is often brick red, or rose red.
The maximum allowable concentration of metallic cobalt and cobalt oxide is 0.5 mg/m3. Respiratory masks, dust-proof overalls, and protective gloves should be used during work to protect the respiratory organs and skin. When working with metal cobalt dust at work, it is recommended to wash your hands with a paste. Dust and dust should be paid attention to during production, and wet operation should be adopted.