Advanced oxidation processes: photo-electro-Fenton remediation process for wastewater contaminated by organic azo dyes

Water pollution is a global problem that needs to be amended and assessed in water resources policies at all levels. The presence of azo dyes pollutants in the environment has become of major concern in the last decades. In this context, oxidation processes are preferred to degrade organic substances present in wastewater. Efforts presented by the scientific community in recent years towards the development of numerous green chemical processes and wastewater treatment technologies are discussed. Advanced oxidation processes are effective treatments for the purification of water and reuse. In aqueous solution, the choice of the Fenton's reagent is important, to generate enough radicals to oxidise pollutants. Novel indirect electro-oxidation methods like photo-electro-Fenton have been recently proposed to enhance the efficiency of electro-Fenton in undivided cells taking into account the catalytic action of UVA light and the alternative use of a sacrificial iron anode, respectively. Fundamentals, experimental set-ups and environmental applications of these emerging procedures, particularly photo-electro-Fenton, are discussed in this review article.