Photocatalysts synthesized via plant mediated extracts for degradation of organic compounds: A review of formation mechanisms and application in wastewater treatment

Abstract

Photocatalysis is a promising technology to remove several persistent and recalcitrant pollutants in water and wastewater. Most of the conventional chemical and physical synthesis routes of photocatalysts result in the release of toxic pollutants to the environment and hence green synthesis is a better alternative. Green synthesis of photocatalyst using plants, fungi, bacteria, yeast, and other biological sources is widely explored in recent years. The presence of various biomolecules used in green synthesis replaces conventional reducing and stabilizing agents such as hydrazine, sodium borohydride, ascorbic acids, and other polymer substitutes. This review focuses on the synthesis of photocatalysts using plant extracts through different synthesis routes and explores the efficacy of photocatalyst synthesized via plant extract mediated synthesis routes in the photodegradation of organic compounds present in water. The pathway as well as the factors affecting the formation of photocatalysts, the role of plant extract in the photocatalytic properties are explored in detail. The action of plant-mediated photocatalyst on the pollutant and the underlying predominant degradation mechanism are also discussed. Besides, this study gives an insight into the recyclability of the photocatalyst synthesized via plant extract mediated synthesis routes and addresses future perspectives and the challenges of green photocatalysts.