Three-Dimensional Electro-Fenton Degradation Of Semi-Coking Wastewater Based CNTs/Fe₃O₄

Semi-coking wastewater is a representative industrial organic wastewater with high concentration and many un-biodegradable substances, which will be discharged into water body if it is let out into river without disposing. Currently, the biochemical treatment method is widely adopted to treat tht diluted semi-coking wastewater with domestic sewage, but it needs high investment and treated water failed to meet the appropriate national standards. In this paper, 3D-E-Fenton system is used to treat simi-coking wastewater. The 3D-E-Fenton system based on Fenton, whith chold activate molecule oxygen to produce more H2O2 and ·OH. The 3D-E-Fenton system is used to treat simi-coking wastewater. The results showed that the treatment could effectively improve the biodegradability of simi-coking wastewater.First, Multi-wall carbon nanotubes/ magnetic nano-Fe₃O₄ composite（CNTs/ Fe₃O₄ NPs） was prepared by chemical co-precipitation and characterized by BET, XRD and TEM. Phenol in aqueous solution was effectively degraded by an electro-Fenton（E-Fenton） system using CNTs/ Fe₃O₄ NPs modified graphite electrode as cathode. The degradation of phenol in this E-Fenton system reached 92% in 120 min at pH =5 and when the voltage was applied at 5 V. The mechanism of the E-Fenton degradation of phenol was discussed briefly. Cyclicvoltammetry（CV） experiments revealed that nano-CNTs/ Fe₃O₄ material modified graphite electrodes accelerated the two-electron reduction of O2 to H2O2, ferrous ions dissolute from CNTs/Fe₃O₄ nanocubes reacted with H2O2 to form Fenton reaction which produced ?OH for degradation of phenol.A now 3D-E-Fenton system was bulit with CNTs/ Fe₃O₄ NPs as particle electrodes and Ti/SnO2 was used as the anode, in order to improve the efficiency of current. Ti/SnO2 electrode was characterized by Nyquist plots of impedance spectra and the cyclic voltammograms.The optimal catalytic oxidation condition of degradation pyridine in 3D-E-Fenton system was voltage 12 V,pH=3, CNTs/Fe₃O₄ =1.5 g/mL.The 3D-E-Fenton system based on CNTs/ Fe₃O₄ NPs is used to treat simi-coking wastewater. The result showed that the CODcr, BOD5 and chroma of simi-coking wastewater removed effectively. Te biodegradability of simi-coking wastewater improve from 2.3% to 10.5% after electrical stripping. The CODcr, BOD5 and chroma of simi-coking wastewater are 386mg/L, 248mg/L and 30 respectively by electrolyze 4 hour.