Characterization and mechanism of p-nitrophenol removal based on modified nanoscale zero-valent iron electrocoagulation

Abstract

p-Nitrophenol (PNP) is a toxic chemical and is difficult to degrade naturally when it enters the environment. It is of great importance to develop methods to remove PNP efficiently and safely. Electrocoagulation has been widely used for the removal of PNP, but challenges remain in the improvement of anode materials and solid-liquid separation of PNP-containing precipitates. In this work, the characteristics and mechanism of activated biochar (ABC) and sulfide dual-modified nanoscale zero-valent iron (nZVI) electrocoagulation anode for the removal of PNP were systematically investigated. The synergistic effect of magnetic iron oxide generated by zero-valent iron oxidation and electrochemical oxidation technique was used to rapidly reduce the PNP concentration for water purification. The results showed that the modified nZVI anode had higher electrocoagulation activity than the iron sheet anode, and the S-nZNI/ABC anode had the highest PNP removal efficiency. The main component of the precipitate after the reaction was Fe3O4, which facilitated the magnetic solid-liquid separation of the precipitate and scum. The seed germination test confirmed that the electrocoagulation material synthesized in this work had almost no adverse effects on the ecological environment. The electrocoagulation process had good degradation performance for PNP, which could significantly attenuate the ecotoxicity of PNP in the aquatic environment and thus improve the water quality. It is expected that this work may provide design references and ideas for the efficient degradation of PNP and the application of electrocoagulation.