Recent advances in photocatalytic materials and their applications for treatment of wastewater: A review

Recent transition in chemicals used in industries has resulted in increased non-biodegradable refractory compounds in effluents, adversely affecting water quality of receiving streams. Enforcement of stringent effluent discharge standards time and again has called for newer and more efficient technologies. Advanced Oxidation Processes (AOPs) are therefore crucial for efficient degradation of these refractory compounds. Photocatalysis is a promising AOP for treatment of various effluents due to its efficient and cost-effective application. This paper is a critical review of performance of various potential photocatalytic materials such as metal oxides, metal sulphides, magnetic materials, carbon-based materials and some other materials. Their performance for treatment of real wastewater has been reviewed, including surface area, operating conditions (catalyst dose, reaction time, pH, flow rate, oxidizing agents used), influent parameters and removal of pollutants. It has been distinctly identified which materials and heterojunctions are suitable for which applications. However, most studies have been done at lab-scale. Also, efficiency of most materials such as SnO2, CuO, WO3, BiFeO3 etc., has been evaluated for only a single application. Based on this review, it has been observed that many photocatalytic materials are available for the process; however, scalability and robustness of the system are major challenges.