borate

Borate refers to salts and esters of boric acid, B(OH)3, and to the borate anions derived from it. In aqueous solution, boric acid acts as a weak acid and is converted to the borate anion B(OH)4−; borates also include polyborate species with complex three- and four-coordinate boron. In solid form they appear as salts such as sodium borate (borax, Na2B4O7·10H2O), sodium metaborate, and calcium borate.

Natural occurrence and minerals: Borates occur in evaporite deposits and are mined worldwide. The best-known borate mineral is borax (sodium borate decahydrate); others include kernite (NaBO2·3H2O) and colemanite (Ca2B6O11·5H2O). They are often found with boron-rich brines and other borate minerals.

Production and processing: Industrially, borates are obtained from natural deposits or produced by treating boric acid with bases to form borate salts. They are also produced as byproducts of other boron-containing minerals. In the laboratory, borates serve as buffers and as precursors to boron-containing esters.

Uses: Borates are widely used in glass and ceramics manufacturing to improve thermal resistance and lower melting temperatures. They serve as flame retardants and as components in detergents, cleaners, cosmetics, and pesticides. They also function as buffering agents and stabilizers in various chemical formulations.

Safety and regulation: Borates generally exhibit low acute toxicity, but ingestion or prolonged exposure can be harmful. Dust can irritate the respiratory tract; some boron compounds have reproductive toxicity in animals at high doses. Proper handling and disposal are advised, and use in consumer products is subject to regulatory limits in many jurisdictions. See also boric acid and borax.