Photo-electrochemical degradation of wastewaters containing organics catalysed by phosphate-based materials: a review

Over the last few years, new advanced oxidation processes (AOPs) have been developed to the removal of organic pollutants from waters and wastewaters. The effectiveness of these AOPs as powerful way for the removal of POPs is related to the in situ production of strong oxidative species such as the hydroxyl radicals (center dot OH). Among the techniques involving AOPs, photo-electrocatalysis (PEC) has come out as a powerful AOP consisting of the combination of both photocatalytic and electrocatalytic processes for the objective to retard and/or avoid the fast recombination of the formed electron/hole pairs during the PEC. This can be achieved by the extraction of the photogenerated electrons directed to the cathode when an external bias potential is applied to the photoanode. This general and critical review deals with the application of PEC to the remediation of organic pollutants from wastewaters (i.e. dyeing effluents) using phosphate-based photoanodes namely BiPO4, Ag3PO4, Cu-2(OH)PO(4)and others. A detailed description of the PEC power of different photoanode has been discussed. The fundamentals and main applications of photo-electrochemical oxidation are reported. Finally, some critiques are proposed in order to improve and develop new effective photoanodes with perspectives to industrial applications.