Epigrammatic progress on the photocatalytic properties of ZnO and TiO2 based hydroxyapatite@photocatlyst toward organic molecules photodegradation: A review

Hydroxyapatite (HA), Ca10(PO4)6(OH)2, is a phosphate material widely used in biomedicine, especially for bone implant manufacture, due to its biocompatibility and environmental management. It is a very promising candidate for the treatment of air, water, and soil pollution because of its capability of effectively adsorbing many pollutants on its surface, its ion-exchange capability, and its good thermal stability. HAs are known for their good photocatalytic properties that stimulate their involvement in polluted water treatment. Thus, several studies reported on HA being used as a photocatalyst, either on its own or combined with other photocatalyst materials. This literature review will first provide a general overview of HA structure, properties, synthesis methods, and applications. Then, it will focus on its role alone as an adsorbent and as catalytic supports for metals in synergy with metal oxides to improve their catalytic efficiency in the wastewater treatment process.