An Iron-doped Cathode with PEI/MWCNT Modified Carbon Felt Outer Layers for Dyeing Wastewater Treatment by Electro-fenton System

TAO Huchun†, SHI Gang, YU Taian, Li Jinlong, LI Jinbo, XU Nan

Shenzhen Key Laboratory for Heavy Metal Pollution Control and Reutilization, School of Environment and Energy, Peking University Shenzhen Graduate School, Shenzhen 518055; † E-mail: taohc@pkusz.edu.cn

Abstract An iron-doped (using limonite as the source of iron) cathode with PEI/MWCNT (polyethylenimine/ Multiwalled carbon nanotube) modified carbon felt outer layers was prepared for Electro-fenton systems. PEI/MWCNT multi-layers could significantly increase the production of H2O2. The highest H2O2 accumulation was achieved up to 66.5 ± 2.4 mg/l at −0.95 V, neutral ph and 200 ml/min of aeration rate, which increased about 56.8% than the carbon felt at the same condition. The PEI/MWCNT multi-layers were stable enough that there was no obvious decrease in H2O2 accumulation after 20 recycles. This study tested the performance of the prepared cathode in treating the simulated dyeing wastewater. The results were as follows: Orange II with initial concentration of 20 mg/l at neutral ph (ph0=67) was discolored completely after 60 min electrolysis process, and the decolorizing efficiency was up to 96.8%. In addition, the prepared cathode was stable enough and could be reused without catalytic activity decrease. This study also tested the performance of the prepared cathode in treating the actual dyeing wastewater. The chroma, COD and ammonia-nitrogen removal efficiency after 120 min electrolysis process were 91.7%, 69.4%, and 56.2% respectively. Key words Electron-fenton; MWCNT; limonite; Orange Ⅱ dye; dyeing wastewater