Removal of nitrophenols and their derivatives by chemical redox: A review

This review intends to provide an overview of chemical redox degradation of nitrophenols (NPs) and their derivatives. The main scientific focus is on the degradation of NPs by advanced oxidation processes (AOPs, such as microwave assisted catalytic oxidation, ultrasound-enhanced oxidation, electrochemical oxidation, catalytic ozonation, photocatalytic oxidation, persulfate and peroxymonosulfate oxidation, etc.), advanced reduction processes (ARPs, such as zero valent iron, bimetals and NaBH4 with precious metal catalysts), and their synergistic processes. The strengths and weaknesses of various treatment technologies are described. The degradation mechanisms of NPs by chemical redox treatment are proposed and summarized. Other aspects such as mechanism of chemical redox, and degradation pathways of NPs, are also discussed in detail. Furthermore, pretreatment of real industrial wastewater containing NPs was introduced according to the reports. The combination of chemical redox and biological treatments for the real industrial wastewater was finally evaluated and discussed significantly.