Calcium Hydroxide

About This Product

Calcium hydroxide, Ca(OH)2 with CAS number 1305-62-0, is a white powder produced by slaking quicklime with water. It is only sparingly soluble, around 1.7 grams per litre at 20 degrees Celsius, and a saturated solution is limewater at about pH 12.4. That low solubility is a functional advantage rather than a limitation. Dosed as a slurry into an effluent stream, only as much lime dissolves as the acidity present can consume; the remainder stays as suspended solid and dissolves progressively as more acid arrives. The result is a self-limiting reagent that is very difficult to overdose into dangerous alkalinity, unlike caustic soda, which dissolves completely and will overshoot with a moment's inattention. At a fraction of the cost per tonne of alkalinity, that makes lime the default for bulk neutralisation, water softening and flue gas desulphurisation. In construction it is the binder in lime mortar and plaster, which set by reabsorbing carbon dioxide to return to calcium carbonate, a slow process that gives lime mortar its characteristic flexibility and self-healing behaviour. It is also used in soil stabilisation and sugar refining. It is used in water and wastewater treatment, flue gas desulphurisation, construction mortars and plasters, soil stabilisation, sugar refining and paper manufacture. Bio Green Chem supplies calcium hydroxide to specification on available Ca(OH)2, calcium carbonate, magnesium, insolubles, fineness and heavy metals.