An Evaluation of Phosphogypsum (PG) -Derived Nanohydroxyapatite (HAP) Synthesis Methods and Waste Management as a Phosphorus Source in the Agricultural Industry

As a raw material, phosphorus availability in agriculture has been a critical concern in terms of phosphate rock consumption related to a price-dependent supply-demand chain. Novel approaches have been proposed for alternative phosphorus sources in agricultural applications. Although nano-hydroxyapatite (nHA) is a commonly used bioceramic material, its utilization as an alternative phosphorus fertilizer is an emerging field. Phosphogypsum (PG), a by-product of wet process phosphoric acid production, is a promising raw material for nHA production. With an approximate 300 Mton annual accumulation rate of PG puts pressure on the research for introducing alternative strategies for the resource utilization of legacy PG piles in an environment-friendly and cost-efficient manner. Valorization of PG as the calcium and phosphorus precursor in nHA production would both provide an efficient waste management strategy and low-cost raw material. This study gives a brief review of the various synthesis routes on PG-derived nHA and criticizes nHA utilization as a phosphorus fertilizer.