Calcium Hypochlorite

Chemical Description

Calcium hypochlorite is a white solid that is commonly used as a swimming pool disinfectant.

Preparation

Calcium hypochlorite is manufactured by two main processes, the socalled “calcium process” and the “sodium process”. These are essentially the same as described for the Mg(ClO)2 salt method given above except that a sodium hypochlorite salt is used in one case and a calcium chloride salt in the other. The products are nearly the same. Calcium hypochlorite is manufactured by the calcium process: 2Ca(OH)2＋2Cl2→Ca(ClO)2＋CaCl2＋2H2O In another method developed for the manufacture of Ca(ClO)2, chlorine gas is reacted with calcium hydroxide: Ca(OH)2＋ 2Cl2→Ca(ClO)2＋ 2HCl In this method, it is claimed that the excess HCl is neutralized by excess Ca(OH)2 to form CaCl2. The product is said to be more “neutral” chemically and more stable than that produced by other methods.

Reactions

As strong oxidant, calcium hypochlorite may react with vigor in combination with carbon compounds, and combination with finely divided carbon particles forms an explosive mixture. Reaction with acetylene leads to creation of explosive chloroacetylenes. Contact with organic matter, oil, hydrocarbons and alcohols such as methanol or ethanol may cause a violent explosion. Reaction with nitromethane causes a delayed violent reaction. Organic sulfur compounds such as sulfides react by self-ignition and explosion. Iron oxide in metal containers catalyze oxygen-evolving decomposition of the oxidant.

Reactivity Profile

CALCIUM HYPOCHLORITE is a powerful oxidizing agent, particularly in the presence of water or at higher temperature as Calcium hypochlorite decomposes to release oxygen and chlorine gases. As strong oxidant Calcium hypochlorite may react with vigor in combination with carbon, especially finely divided is explosive; acetylene, leads to creation of explosive chloroacetylenes; organic matter, oil, hydrocarbons; alcohols may cause explosion, methanol, ethanol, etc.; nitromethane caused delayed violent reaction; organic sulfur compounds, sulfides tend toward ignition and sometimes explosion; with iron oxide in metal containers catalyze oxygen evolving decomposition of the oxidant. Calcium hypochlorite forms highly explosive NCl3 on contact with urea. Produces highly toxic gaseous chlorine gas when heated or on contact with acids [Sax, 9th ed., 1996, p. 1905]. Mixture of damp sulfur with hypochlorite caused a violent reaction, that ejected molten sulfur, Chem Eng. News, 1965, 46(29), 6.

Health Hazard

Inhalation, ingestion or contact (skin, eyes) with vapors or substance may cause severe injury, burns or death. Fire may produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may cause pollution.

Fire Hazard

These substances will accelerate burning when involved in a fire. Some may decompose explosively when heated or involved in a fire. May explode from heat or contamination. Some will react explosively with hydrocarbons (fuels). May ignite combustibles (wood, paper, oil, clothing, etc.). Containers may explode when heated. Runoff may create fire or explosion hazard.

Shipping

UN1748 Calcium hypochlorite, dry or Calcium hypochlorite mixtures dry with .39% available chlorine (8.8% available oxygen), Hazard Class: 5.1; Labels: 5.1- Oxidizer. UN2208 Calcium hypochlorite mixtures, dry, with .10% but not .39% available chlorine, Hazard Class: 5.1; Labels: 5.1-Oxidizer. UN2880 Calcium hypochlorite, hydrated or Calcium hypochlorite, hydrated mixtures, with not ,5.5% but not .16% water, Hazard Class: 5.1; Labels: 5.1-Oxidizer

Incompatibilities

A powerful oxidizer. Decomposes in heat or sunlight; becomes explosive above 100C/212F. Incompatible with strong acids; water and other forms of moisture, reducing agents; combustible materials; all other chemicals, especially acetylene, aniline and all other amines, anthracene, carbon tetrachloride, iron oxide, manganese oxide, mercaptans, diethylene glycol monomethyl ether, nitromethane, organic matter; organic sulfides, phenol, 1-propanethiol, propyl mercaptan, sulfur, turpentine, organic sulfur compounds. Attacks various metals, releasing flammable hydrogen gas.

Waste Disposal

Dissolve the material in water and add to a large volume of concentrated reducing agent solution, then acidify the mixture with H2SO4. When reduction is complete, soda ash is added to make the solution alkaline. The alkaline liquid is decanted from any sludge produced, neutralized, and diluted before discharge to a sewer or stream. The sludge is landfilled

Chemical Composition

Calcium hypochlorite (Ca(ClO)2) is an inorganic calcium salt containing hypochlorite. It is a strong oxidant and its aqueous solution is alkaline.

Role as a Bleaching Agent

Calcium hypochlorite has a role as a bleaching agent and is commonly used for industrial sterilization, water treatment, and bleaching processes.

Postharvest Disinfection

Calcium hypochlorite is utilized for postharvest disinfection of fruits and vegetables due to its strong sterilization ability and minimal impact on human health. It is effective in sterilizing produce surfaces while preserving their quality.

Properties and Uses

Properties and Uses of calcium hypochlorite are similar to those of sodium hypochlorite. It is shipped in dry form and needs to be dissolved in water for use in postharvest produce treatment, making shipping more cost-effective compared to sodium hypochlorite, which is only stable in solution.

Water Purification

Calcium hypochlorite is dissolved in distilled water for industrial sterilization and water treatment purposes. It is relatively stable and has a higher available chlorine content compared to sodium hypochlorite.

Antimicrobial Action

Studies have shown that calcium hypochlorite solutions have antimicrobial action against bacteria such as Enterococcus faecalis, making it effective for disinfection purposes.

Industrial Applications

Calcium hypochlorite is utilized in various industrial processes, including flotation separation of sulfide minerals, disinfection of swimming pools and food containers, and bleaching of cellulose due to its strong oxidizing properties.

Physical properties

White crystalline solid; density 2.35 g/cm3; decomposes when heated to 100°C; soluble in water and alcohol (with decomposition).

Definition

A white solid that can be regarded as a mixture of calcium chlorate(I) (calcium hypochlorite), calcium chloride, and calcium hydroxide. It is prepared on a large scale by passing a current of chlorine through a tilted cylinder down which is passed calcium hydroxide. Bleaching powder has been used for bleaching paper pulps and fabrics and for sterilizing water. Its bleaching power arises from the formation, in the presence of air containing carbon dioxide, of the oxidizing agent chloric(I) acid (hypochlorous acid, HClO): Ca(ClO)2.Ca(OH)2.CaCl2 + 2CO2 → 2CaCO3 + CaCl2 + 2HClO.

General Description

Calcium hypochlorite, hydrated is a white granular solid or tablets compressed from the granules having an odor of chlorine. Calcium hypochlorite is noncombustible, but Calcium hypochlorite will accelerate the burning of combustible materials. Calcium hypochlorite is decomposed by water with evolution of chlorine gas and heat. Prolonged exposure to fire or heat may result in the vigorous decomposition of the material and rupture of the container. Material containing less than 39% available chlorine may undergo reactions as described above though Calcium hypochlorite may take longer to initiate, and the resulting reactions may not be as vigorous. Calcium hypochlorite is used for water purification, disinfectant for swimming pools, for bleaching paper and textiles, and for many other uses.

Industrial uses

Calcium hypochlorite Ca(OCl)2 can be found in swimming pool disinfectants, in bleaching agents, in deodorants and in fungicides.