Electro-Fenton oxidation of printing and dyeing wastewater with CO2 activated CuFeC and CuMnC aerogel cathode

Abstract

An electro-Fenton (EF) system with CuFeC and CuMnC aerogel cathodes was proposed without an additional Fe2+ or H2O2 for the efficient degradation of actual printing and dyeing wastewater (PDW). The CO2 activated CuFeC aerogel as the cathode showed the highest chemical oxygen demand (COD) removal efficiency compare to other cathodes. Structural characterization revealed that CO2 activation significantly enlarged the cathode porosity and surface area to increase the exposure of active sites to catalysis. During a 60 min experiment, the COD removal in the EF system with CO2–activated CuFeC and CuMnC aerogel cathodes reached 72.8 % and 51.5 %, respectively. The high COD removal of PDW with CO2-activated CuFeC aerogel could be achieved at a wide range of pH values (3~8). The enhanced mineralization efficiency of the CuFeC aerogel was mostly attributed to the synergistic effect between Fe and Cu, which benefited the oxygen reduction reaction (ORR) ability to produce more H2O2 and generate more in-situ ·OH. The possible oxidation pathway of 2, 4, 6-trichlorophenol was proposed via an intermediate study. Moreover, the CO2–activated CuFeC aerogel presented low Fe and Cu leaching in an acidic solution and a long operational life span. This material can provide a feasible way for actual PDW purification through the EF process.