Study On Perovskite Sr_xLa_1-xMn_yCo_1-yO_3-δ Electrode For Efficient Electrocatalytic Oxidation Of Organic Wastewater

Electrocatalytic oxidation technology can effectively purify organic sewage,but how to prepare anode materials with high efficiency,stability and low cost has become one of the key problems restricting the development of this technology.In this thesis,perovskite Sr_xLa_1-xMn_yCo_1-yO_3-δwere prepared by sol-gel method,and then uniformly coated on a titanium plate as an anode to purify organic wastewater.This research has important theoretical significance and high application value.In this paper,11 types of perovskite named the pristine La Co O₃,La Mn_yCo_1-yO_3-δ（the molar ratio of Mn:Co=1:9,1:4,3:7,2:3,5:5）and Sr_xLa_1-xMn_0.4Co_0.6O_3-δ（the molar ratio of Sr:La=1:9,1:4,3:7,2:3,5:5）were prepared by adjusting the amount of different metal nitrates through processes such as water bath heating,air drying,and high temperature calcination.SEM,FT-IR,XRD and EDS were used to characterize the perovskites’physical properties,and EIS,CV,LSV,and Tafel curves were used to test the electrochemical performance of representative perovskite-coated electrodes.In order to optimize the electrolysis conditions such as electrolysis time,electrolysis temperature,current density,p H,chloride ion concentration,etc.,200 mg/L ammonia nitrogen（prepared with ammonium sulfate）mixed with 20 mg/L methyl orange was used as simulated wastewater.Besides,the current efficiency and the removal ratio of targeted pollutants and COD were used as indicators to judge the electrodes’performance.Under the same system,the stability,reusability,and universality of the electrode were also studied.Moreover,the radical scavenger experiment was adopted to confirm the key oxidized species.Finally,under the optimal operation conditions,the degradation of the actual organic wastewater like landfill leachate by the new electrode was investigated and the energy consumption was evaluated.The characterization results demonstrated that the synthesized materials all had obvious perovskite structure,and the elements Sr and Mn had been successfully doped into the lattice of La Co O₃according to the expected ratio.The electrochemical test and electrolysis results indicated that when the molar ratio was Mn:Co=4:6 and Sr:La=3:7,the activity of titanium-based perovskite-coated electrode Ti/Sr_0.3La_0.7Mn_0.4Co_0.6O_3-δwas the highest,with which the removal ratio of ammonia nitrogen and methyl orange in the simulated wastewater reached 98.23%and 99.61%with the contribution of·OH,·O₂^-and active chlorine under the optimal electrolysis conditions,namely T=25℃,t=60 min,i=20 m A/cm²,p H=9,C_Cl-=2000 mg/L.After five cycles of the anode,the removal ratio of ammonia nitrogen still maintained above95%,and it also showed good degradation effect on the complex system containing ammonia nitrogen and different dyes such as methylene blue,acid orange 7 and rhodamine B.After 2 hours’electrolysis for landfill leachate,the removal ratio of COD and ammonia nitrogen reached 85.43%and 96.12%,respectively,and the calculated specific energy consumption was 26.88 k Wh（Kg COD）^-1.The novel anode Ti/Sr_0.3La_0.7Mn_0.4Co_0.6O_3-δstudied in this subject showed good comprehensive performance and was expected to play a promising candidate in the treatment of organic wastewater with ammonia nitrogen.