Non-fertilizer uses of phosphorus: an overview

Phosphorus is a non-substitutable element required for the storage of genetic information, energy transfer and the structural integrity of biological systems. Agricultural use of phosphorus fertilizers and supplements aims to balance the biological phosphorus stoichiometry, for optimal growth and yield of crops and animals. Most of the commercial phosphorus industry aims to produce phosphates and polyphosphates for agricultural sector, particularly for fertilizer, animal feed and the food/beverage industries. However, about 10% of the mineral resources are allocated for non-fertilizer uses via thermal processing of phosphate rock to elemental phosphorus as the tetrahedral P4 molecule, which is then stabilized as P4 derivatives for controlled production of hundreds of phosphorus-containing compounds with diverse chemistry and practical uses. True P4 derivatives are made only from P4 and include intermediates such as phosphorus pentoxide (P2O5), phosphorus trichloride (PCl3), phosphorus oxychloride (POCl3), phosphorus pentachloride (PCl5), phosphorus pentasulphide (P2S5), phosphines (containing PH3), red P (amorphous elemental P designated P21), hypophosphites (ionic form H2PO2-) and phosphides (reduced form P3-). This review explains the synthesis and applications of these non-fertilizer phosphorus compounds as flame retardants and plastic stabilizers, for metal sequestration and extraction, in catalyst ligands, as electrolytes in batteries, as crop protection agents and as anti-wear substances.