Chlorinated Lime

chlorinated lime [′klȯr·ə‚nād·əd ′līm]

(materials)

bleaching powder

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Chlorinated Lime 

(also chloride of lime, bleaching powder), a complex mixture of calcium hypochlorite, Ca(ClO)₂, calcium chloride, CaCl₂, slaked lime or calcium hydroxide, Ca(OH)₂, and water of crystallization. It is obtained as a white, hygroscopic powder, with a chlorine odor. Its dry weight is about 500 kg/m³. The composition of commercial chlorinated lime is approximately 1.5Ca(ClO)₂ · 1.5(CaCl₂ · 3Ca(OH)₂ · nH₂O; it contains 28 to 38 percent active chlorine (that is, the chlorine released during the reaction of lime with hydrochloric acid) and about 10 percent water.

Chlorinated lime is produced by the interaction of chlorine gas and slaked lime. It slowly decomposes during storage, losing about 10 percent of the active chlorine per year; in air, the decomposition is accelerated by the absorption of moisture and carbon dioxide. Chlorinated lime decomposes vigorously in the presence of organic impurities or salts of certain metals (Fe, Ni, and Co) that act as catalysts; it also decomposes when heated vigorously. It is a strong oxidizing agent.

Stable chlorinated lime containing 2 percent water is also produced (the loss of active chlorine is 7 to 9 percent in eight years). Obtained by chlorinating slaked lime in a fluidized bed at an elevated temperature, it is a strong oxidizing agent and is used in medicine as an antiseptic to disinfect rooms and dishes and to chlorinate water and decontaminate waste matter.

To a limited extent, chlorinated lime is used for bleaching wood pulp and fabrics and in chlorination.

REFERENCES

See references under .