Calcium hypophosphite (CHP) is an inorganic compound with formula Ca(H2PO2)2. It is a colourless crystalline solid that is widely used in various industrial applications.
Physical and Chemical Properties
Calcium hypophosphite has a molecular weight of 162.09 g/mol. It is soluble in water and slightly soluble in ethanol. CHP decomposes above 130°C to release phosphine gas (PH3). It is stable under normal storage conditions but can ignite or detonate upon contact with strong oxidizing agents. Calcium hypophosphite has a role as a reducing agent due to the presence of the hypophosphite ion H2PO2-. It is also slightly acidic with a pH of around 5-6 in water solution.
Production
On an industrial scale, Calcium Hypophosphite
is produced through the reaction of calcium hydroxide with phosphorous acid. Phosphorous acid is produced by oxidizing white phosphorus. The chemical reactions are as follows:
P4 + 5O2 → 4H3PO3 (Oxidation of white phosphorus to phosphorous acid)
Ca(OH)2 + 2H3PO3 → Ca(H2PO2)2 + 2H2O
(Reaction of phosphorous acid with calcium hydroxide to form calcium hypophosphite)
The white phosphorus is first oxidized to produce phosphorous acid. Then calcium hydroxide and phosphorous acid are reacted in a batch process with continuous stirring to precipitate calcium hypophosphite. The product is filtered, washed and dried.
Uses in Industry
Some major industrial applications of calcium hypophosphite include:
– Flame Retardant: CHP is used as a flame retardant in plastics, textiles, paper etc. due to its endothermic decomposition and reducing properties. It helps absorb heat and slows down combustion.
– Wood Treatment: Calcium hypophosphite solutions are used as wood preservatives and protectants. It protects wood from fungal decay, rot and insect attacks.
– Leather Treatment: The compound is employed in leather tanning and dressing processes. It acts as a buffering agent, reduces pollution and improves quality.
– Welding Rod Coating: CHP protects welding rods from moisture by its hygroscopic nature. It prevents hydrogen embrittlement in welds.
– Pharmaceuticals: It has applications as a stabilizer in certain pharmaceutical formulations due to its antioxidant effects.
– Water Treatment: Calcium hypophosphite finds use as a sequestrant in boiler feedwater and industrial cooling water treatment.
– Agriculture: Low concentrations of CHP are used as a fertilizer supplement for plants. It supplies phosphorus and has some antibacterial properties.
Safety and Handling
As calcium hypophosphite may cause irritation to eyes and skin, protective equipment should be worn while handling. It is non-toxic by ingestion but the dust can cause respiratory issues if inhaled. Calcium hypophosphite powder is hygroscopic and may spontaneously ignite when exposed to air. Care must be taken to store and transport the compound away from heat and moisture. Proper ventilation is advised while working with calcium hypophosphite in industrial facilities. In case of any exposure, eyes must be flushed with water and medical assistance sought immediately.
calcium hypophosphite is a versatile reducing agent and inorganic compound used across many industries ranging from flame retardants and wood treatment to welding and pharmaceuticals. With proper safety precautions during production, storage and handling, it serves as an important industrial chemical due to its hygroscopic and antioxidant properties. Further research continues to explore new applications of this multifunctional compound.
*Note:
1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it