Degradation Of Rhodamine B Wastewater By ?-PbO₂/SnO₂-Sb₂O₃/Ti Anodic Oxidation Coupling With Persulfate

In recent years,the advanced oxidation technology based on sulfate radical?SR-AOPs?has attracted much attention.The oxidation and stability of SO₄^·-are stronger than·OH.At present,SO₄^·-is mainly produced by activating persulfate.The mature activation methods include thermal activation,photoactivation,transition metal activation,alkali activation,and so on.However,these activation methods have some shortcomings,such as low energy utilization and catalytic efficiency.The electrochemical activation can ensure environmental friendliness and improve economy while activating efficiently.Therefore,this paper aims to achieve the degradation of organic pollutants by electrochemical activation of persulfate.At the same time,in order to further enhance the degradation efficiency of electrochemically activated persulfate system,the anode materials of the electrochemical system were optimized and screened,and?-PbO₂/SnO₂-Sb₂O₃/Ti was prepared and used as anode material,due to its high oxygen evolution potential,strong electrocatalytic activity and mechanical properties.The pollutants were degraded by anodic oxidation coupled with persulfate oxidation.The main contents and conclusions of this paper are as follows:?1?The modified anode material,?-PbO₂/SnO₂-Sb₂O₃/Ti,was prepared by thermal decomposition-electrodeposition method,and the electrodeposition conditions of lead dioxide surface active layer were optimized.Scanning electron microscope?SEM?showed that Sn-Sb interlayer adhered uniformly without cracks and agglomeration,and the modified active layer had relatively small grain size and complete and compact crystal.X-ray diffraction?XRD?spectra indicated that SnO₂ and Sb₂O₃ are the main components of the intermediate layer,and according to the JCPDS card?#41-1492?,the preferential orientation of the diffraction peaks of the surface layer is?-PbO₂.The electrochemical properties of?-PbO₂/SnO₂-Sb₂O₃/Ti electrodes were investigated by electrochemical tests.?2?The degradation of rhodamine B?RhB?simulated wastewater was investigated by electrochemical advanced oxidation system?EAOP?using?-PbO₂/SnO₂-Sb₂O₃/Ti as anode and Ti as cathode.Under the optimum conditions of 40 mmol/L Na₂SO₄,pH=9,20 mA/cm²and 25?,the degradation rate of RhB can reach more than 98%after 60 min.The free radical inhibitor experiment and electron paramagnetic resonance?EPR?analysis suggested that the main active free radical in the system was^·OH;cyclic voltammetry results indicated that RhB could be oxidized directly on?-PbO₂/SnO₂-Sb₂O₃/Ti anode surface.The stability test show that the prepared anode material has good reusability.?3?On the basis of EAOP,the electrochemical coupled persulfate?EC-PS?advanced oxidation system was constructed by adding persulfate.The factors affecting the degradation of RhB in EC-PS system were investigated.After optimizing the degradation conditions,the degradation rate of 10 mg/L RhB wastewater could reach more than 95%in 30 minutes.The degradation efficiency of RhB and TOC in EC-PS coupled system was significantly higher than that in the single electrochemical?EC?and persulfate?PS?systems.Radical inhibitor experiments and EPR analysis confirmed that the main active free radicals in EC-PS system are^·OH and SO₄^·-.In addition,the degradation performance of EC-PS,Fe²⁺-PS and EC-Fe²⁺-PS systems were also compared.Results showed that the synergistic activation of PS by EC and Fe²⁺could enhance the degradation efficiency significantly,due to the electrochemical recycling of iron ions.The effect of Fe²⁺dosage was further investigated and the optimal dosage of n(Fe²⁺):n(S₂O₈^2-)=1 was obtained.