Construction Of Bio-electro-fenton System Based On ?-FeOOH Nanocomposites For Treatment Of Environmental Wastewater

With the rapid development of industrialization,environmental pollution caused by the discharge of all kinds of industrial wastewater has become more and more serious,and increasing demand for water treatment technology have been proposed.Bio-electro-Fenton system is an advanced oxidation technology without additional electrical energy or chemical input.It overcomes the defects of traditional Fenton processes and has gained wide attention as a green and sustainable water treatment technology.The cathode is the limiting factor of the system's power generation and Fenton degradation performance.Therefore,it is an effective strategy to develop cathode materials that can not only promote the in situ generation of H₂O₂,but also activate the decomposition of H₂O₂into·OH.The?-FeOOH is an ideal heterogeneous Fenton catalyst because of its high abundance,low cost,high catalytic activity and stability.In this paper,composite cathode materials were prepared based on?-FeOOH nanorods to construct BEF system for treatment of environmental wastewater.The conditional factors were investigated,and the mechanism of enhanced degradation of pollutants by cathode materials in BEF system was explored.The main research contents are as follows:(1)The?-FeOOH nanorods were prepared by hydrothermal method,and the BEF system was constructed with the?-FeOOH modified cathode for pollutants degradation.The removal rates of MB and TC were 89.31%and 76.28%when the?-FeOOH dosage was 0.035g,initial concentration of MB was 10 mg/L,pH=6 and under the light illumination.The system can be applied to the simultaneous oxidation of MB and reduction of Cr(VI).It has obvious advantages over homogeneous Fenton of Fe²⁺.The·OH was identified as the main active radical in MB degradation process by radical quenching experiment and fluorescence spectrometry.Furthermore,the reaction mechanism in the BEF system was proposed:dual electron reduction of O₂generate H₂O₂,and Fe²⁺generated on?-FeOOH surface activate H₂O₂to produce·OH which finally degrade MB.(2)Two-dimensional Mo S₂nanosheet dispersion was prepared by stripping natural molybdenite in liquid phase and doped into?-FeOOH by in situ hydrothermal method to prepare binary composite catalyst,and the 1wt%Mo S₂/?-FeOOH was used as a modified cathode in BEF system for the degradation of pollutants.Its power density can reach to 292.38m W/m~2.The degradation rates of MB,Rh B and TC were 94.72%,85.43%and 72.34%,respectively.And the simultaneous removal rates of MB and Cr(?)can still reach 94.53%and 100%.The electrode materials have shown the good reusability.The introduction of Mo S₂accelerates the electron transfer to facilitate the in-situ generation of H₂O₂.Moreover,Mo⁴⁺on the electrode surface promoted the redox cycle of Fe(III)/Fe(II)to increase the production of·OH,thus enhancing the degradation of pollutants.(3)The ternary composite electrode material Ce_0.2Fe_0.8OOH/10wt%TiO₂was prepared by doping TiO₂nanoparticles into the?-FeOOH of Ce isocrystal substitution,which was used as the modified cathode of BEF system.The removal rates of MB and TC at 10 mg/L can reach 100%and 99.81%,respectively under light conditions,and corresponding mineralization rates were 70.35%and 75.69%,which were significantly higher than that of Ce_0.2Fe_0.8OOH and?-FeOOH cathodes.This is mainly attributed to the excellent photoelectrocatalytic and Fenton catalytic performance of Ce_0.2Fe_0.8OOH/10wt%TiO₂.The·OH produced in the system was the main ROS to remove MB with synergistic oxidation effect of·O₂^-and h⁺.The introduction of TiO₂improves the utilization rate of light,and the photo-generated electrons and holes participate in the degradation reaction.The cycle between Fe²⁺/Fe³⁺and Ce³⁺/Ce⁴⁺on the surface of the catalyst was promoted by the isomorphic substitution of Ce and Fe,which can promote the decomposition of H₂O₂to produce more·OH,thus enhancing the degradation and mineralization of pollutants.