Study On The Electrochemical Remediation Of Heavy Metal And Total Petroleum Hydrocarbon Combined Polluted Water By Manganese Oxide

As China’s urbanization process advances,industrial firms are demolished and transferred,leaving a large number of contaminated sites in the existing urban areas.In terms of ecological function,soil and groundwater are intertwined and mutually causative in the processes that cause pollution,which also contributes to the complexity of shallow groundwater pollution and the predominance of organic-heavy metal complex pollution.δ-MnO₂’s layered structure and chemical characteristics(ample Mn³⁺/Mn⁴⁺ion pairs)make it suitable for use as an electrode for the electro adsorption removal of heavy metal pollutants and the electrocatalytic removal of organic pollutants.Therefore,in this study,δ-MnO₂ active electrode materials with large specific surface area and perfect pore size distribution were created by reducing and boiling potassium permanganate with strong hydrochloric acid,and their performance in the adsorption of heavy metal cadmium（Cd）and catalytic degradation of petroleum hydrocarbons（TPH）was explored,as well as their performance as electrode materials for the electro adsorption of Cd and TPH.Additionally,the reaction conditions for the electrocatalytic system based onδ-MnO₂were improved in order to examine its potential for cleaning up Cd-TPH complex-polluted water bodies.This essay’s primary topics are as follows.Preparation ofδ-MnO₂ and performance analysis of Cd²⁺electro adsorption.The material characterization results revealed that the producedδ-MnO₂was a nano-flake generated by random accumulation and aggregation of nanosheets.Its high specific surface area and ordered mesoporous structure exhibited an excellent electron transfer rate in the electro adsorption experiments,and it was able to remove nearly 91%of Cd²⁺by adsorption at 1.2 V.Theδ-MnO₂electrode’s surface had the most adsorbed Cd²⁺.The adsorption efficiency was strongly influenced by the pH of the solution and the anions in the solution,with lower and higher pH values inhibiting the electro adsorption efficiency and capacity of Cd²⁺.The findings of the remediation studies with simulated groundwater demonstrated that Cl^-had a substantial impact on adsorption efficiency.The Cd²⁺concentrations in the three different electrolyte solutions were below the V water quality level(0.01 mg L^-1)stipulated in the groundwater environmental quality standard after 1h and 4h of treatment with initial Cd²⁺values of 1 mg L^-1 and 5 mg L^-1.The electro adsorption cycling studies further showed that theδ-MnO₂electrode had good cycling stability.A study on the performance of electrically activated persulfate（PS）based onδ-MnO₂electrode for the degradation of TPH.It was shown that aqueous sodium manganese ore aided persulfate’s degradation of petroleum hydrocarbons,and preliminary research revealed that the reaction system was able to achieve a greater degradation rate of TPH（38%）with a smaller catalyst dosage of 0.05 g at a mass ratio of 1:2.5 betweenδ-MnO₂ and PS.The TPH removal rate was further dramatically increased when the PS dosage was increased from 0.05 g to 0.2 g.In the electrocatalytic experiments,the removal of petroleum hydrocarbons was further improved on this basis（63%）for 6 h at a current density of 10 m A cm²,and the solution showed a higher removal of petroleum hydrocarbons under neutral conditions than under acidic（pH=3）or alkaline conditions（pH=11）.The highest Cd removal efficiency（91%）was obtained based on the parameters of 1.2 V and pH 5.5 in the electro sorption experiments and the best oxidative degradation of petroleum hydrocarbons in the electrocatalytic experiments at a current density of 10 m A cm² and an optimum ratio of 1:2.5 betweenδ-MnO₂ and oxidant potassium persulphate.The best experimental conditions of electro adsorption experiment and electrocatalysis experiment were applied to the remediation of petroleum hydrocarbon Cd complex polluted water respectively.It was found that under the current density of 10 m A cm² and solution pH=7,the removal efficiency of Cd by electro adsorption and the oxidative degradation efficiency of TPH were higher than those under the voltage of 1.2 V and pH=5.5.The concentration of heavy metal Cd inhibited the degradation of TPH byδ-MnO₂ activated potassium persulfate to some extent.Based onδ-MnO₂ electrode synchronously realizes the electro adsorption removal of Cd in water and the electrocatalytic degradation of TPH by electrochemical method.The adsorption removal of Cd by current density and the catalytic oxidation degradation of TPH are mainly achieved by anodic oxidation of TPH and cathodic adsorption of Cd.This study can be based onδ-MnO_2。The application of the electro catalytic technology of MnO₂ electrode in the remediation of actual composite polluted water body provides scientific data and useful reference.