CALCIUM HYPOCHLORITE

What is Calcium hypochlorite?

Calcium hypochlorite is an inorganic compound with formula Ca(ClO)2. It is the main active ingredient of commercial products called bleaching powder, chlorine powder, or chlorinated lime, used for water treatment and as a bleaching agent. This compound is relatively stable and has greater available chlorine than sodium hypochlorite (liquid bleach). It is a white solid, although commercial samples appear yellow. It strongly smells of chlorine, owing to its slow decomposition in moist air. It is not highly soluble in hard water, and is more preferably used in soft to medium-hard water. It has two forms: dry (anhydrous); and hydrated (hydrous).

Application

For Bleaching purpose of wood pulp, silk, cloth and fiber-

Disinfectant for water treatment and swimming pools-

Disinfectant for chemical poisonous and radioactive substance-

Disinfectant in aquaculture, Livestock etc-

Normal Packing: 45kg/50kg plastic drum or 50kg iron drum

Usage

100kg of calcium hypochlorite 65% into 1 MT of water. The solution will be bleaching liquid at a density of 6.5% effective chlorine.

1% disinfection liquid can be formulated by adding 1.7 g of calcium hypo 65% into 1 MT of water.

Advantages

High effective chlorine content

Good stability. Can be stored a long time at normal temperature with little chlorine loss

Good solubility, less water-insoluble matters

Sanitation

Calcium hypochlorite is commonly used to sanitize public swimming pools and disinfect drinking water. Generally the commercial substances are sold with a purity of 65% to 73% with other chemicals present, such as calcium chloride and calcium carbonate, resulting from the manufacturing process. As a swimming pool chemical, it is blended with other chemicals less often than other forms of chlorine, due to dangerous reactions with some common pool chemicals. In solution, calcium hypochlorite could be used as a general purpose sanitizer, but due to calcium residue, sodium hypochlorite (bleach) is usually preferred.

Organic chemistry

Calcium hypochlorite is a general oxidizing agent and therefore finds some use in organic chemistry. For instance the compound is used to cleave glycols, α-hydroxy carboxylic acids and Keto acids to yield fragmented aldehydes or carboxylic acids.

Calcium hypochlorite can also be used in the halo form reaction to manufacture chloroform. Calcium hypochlorite can be used to oxidize thiol and sulfide byproducts in organic synthesis and thereby reduce their odour and make them safe to dispose of.

Calcium hypochlorite is a white solid that is added in granular or tablet form to pool water to kill germs that can make swimmers sick. Used properly, by well-trained pool operators, this compound destroys germs that are capable of causing numerous health problems for pool users--diarrhea, swimmer's ear (a nasty earache) and various respiratory, skin and wound infections. Spa and hot tub waters are also disinfected with calcium hypochlorite--it's a chemical wonder that makes healthful water recreation possible. But there is much more to the story of this chlorine compound.

Usage of Calcium hypochlorite

Calcium hypochlorite may be doses as a solution into a flow of water at a constant rate. It can be used for disinfecting installations. It is also used for disinfection of water in batches, typically in disaster situations and for disinfection of water in the home.

Storage and handling

Chemicals should be stored in accordance with manufacturers’ instructions and local safety regulations. This is to ensure both the safety of the operator and that the chemical does not deteriorate.

Bleaching powder and HTH are both commonly supplied in sealed plastic bags or in drums or sometimes jars. Individually sealed plastic bags containing a suitable volume for immediate use (for example 1, 2 or 5 kg) are preferable. Calcium hypochlorite will, however, deteriorate even in such bags, and should be stored properly.

All forms of calcium hypochlorite should be stored in a cool, dark, dry place in closed, corrosion-resistant containers (for instance wood, plastic, ceramic, dark glass or cement). In hot climates, containers may burst if not stored correctly.

When stored in a container opened daily for 10 minutes, calcium hypochlorite loses about 5 per cent of its initial available chlorine in 40 days. If left open for 40 days, about 18 per cent loss is suffered.

As with other disinfecting chemicals, stocks should be dated and controlled, and used in rotation to minimize the effects of deterioration.

Calcium hypochlorite which has been stored badly or which may have deteriorated with time may be tasted to determine its available chlorine content as described below.

Making chlorine solution

For many disinfection purposes it is necessary to dissolve calcium hypochlorite in water, and the clear chlorine solution produced is used as the disinfectant.

All forms of calcium hypochlorite contain some insert material which is insoluble. This must be separated otherwise it may cause clogging and blockage. In general, therefore, the powder is mixed with water in one tank, left to settle and the clear supernatant decanted off into a storage tank. The preparation of calcium hypochlorite solution is shown in figure 1.