Solid-supported photocatalysts for wastewater treatment: Supports contribution in the photocatalysis process

Recalcitrant and dangerous organic contaminants can be degraded using photocatalysis, a green and environmentally friendly method. Photocatalytic wastewater treatment by employing UV or solar-active photocatalyst (PC) particles immobilized on/in solid supports provides new avenues for energy-efficient purification processes compared to using slurry. Fortunately, PC immobilization on/in solid supports can avoid the costly and inefficient post-treatment recovery of wasted photocatalysts on a wide scale. Encouraged by the advantages of this type of photocatalyst, this review focuses on the usage of various supporting mediums to immobilize photocatalysts (PCs) for the degradation of wastewater pollutants. Since photocatalysis is a complex process where optical, electronic, and chemical phenomena occur together to degrade the pollutants, it is shown how the PCs and their supports are chosen to provide the requirements. This work searches the contribution of the utilized organic and inorganic solid supports in the optical, electronic, and chemical steps of photocatalysis, emphasizing the issues. It shows that as the results of a lot of studies regarding solid supports, more stability, reusability, and lowering cost have been achieved while they still suffer from the lack of efficient participation in the optical, electronic, and chemical steps of photocatalysis. From a perspective, opto and electro-active solid supports would be promising candidates for the future development of solid-supported PCs.