Conducting polymers-based photocatalysis for treatment of organic contaminants in water

Aqueous organic contaminants, including dyes, disinfection by-products (DBPs), pharmaceuticals and personal care products (PPCPs), and other emerging contaminants, have been under research lens due to their potential ecotoxicological and adverse health impacts. Semiconductor-based photocatalysis has been considered as one of the most promising approaches to treat organic contaminants in water. Recently, conducting polymers (CPs) and their nanocomposites (CPNs) have attracted much attention due to their tunable electrochemical properties, low costs, and efficacy. The nanocomposites of conducting polymers, with metals and metal oxides, have shown excellent photocatalytic efficiencies for removing organic contaminants, including dyes and PPCPs. This paper presents a critical review of the recent advances in the photocatalysis of aqueous organic contaminants using CPs and CPNs. We have discussed different strategies to prepare CPs and CPNs, characterization of CPs, and factors affecting CP-based photocatalysis. This review also highlights the potential and the promise offered by CPs for the next generation water treatment by discussing unsolved questions, technical challenges, and future directions for CP-based photocatalysis. Although our review highlights CPs as one of the most promising photocatalytic materials to degrade trace organics, most of the CP-based photocatalysis studies to date have been conducted in a batch-scale mode and with dye as a model contaminant. There is a need for more CP-based photocatalytic research, involving real-world water matrices, UV treatment, stability and reusability of catalysts, continuous flow reactor design, cost-benefit analysis, and pilot-scale testing before CPs could find their application in the real-world treatment systems.