| Refractory organic wastewater has become a great issue for the environment due to its high environmental hazards and intractability.Advanced oxidation process based on in-situ free radical production is one of the most effective methods for treating refractory organic wastewater.However,the practical application has been restrained by its high energy consumption and cost.On the one hand,it is necessary to develop high-performance and practical advanced oxidation methods,among which electrochemical advanced oxidation process?EAOPs?demonstrates broad practical prospects due to the advantages of high efficiency,multi-function,simple operation and easy expansion.The cost,performance and stability of the anode largely determine the cost,efficiency and service life of EAOPs,however,the lack of practical anode is the key factor limiting the application of EAOPs.On the other hand,it is necessary to develop low-cost coupling treatment technology of advanced oxidation method and biological method.Among the developed anode materials,antimony-doped tin dioxide?Ti/Sn O2-Sb?electrode holds great promise for application in EAOPs due to the advantages of hydroxyl radical production capability,low cost,environmental friendliness,and easy preparation.However,Ti/Sn O2-Sb electrode suffers from short service life.Given the deactivation process of Ti/Sn O2-Sb electrode is still unclear,this article firstly explores the deactivation mechanisms of undoped and Pd-doped electrodes.The peeling and dissolution loss of catalytic layer,the formation of tin hydroxide layer,the selective dissolution of doped Sb atoms are the main failure causes.Strategies such as Pd-doping can prolong the electrode service life by slowing down these factors.However,Pd-doping will hinder the radical production ability of electrode,and the selective dissolution of doped Pd atoms causes Pd-doped electrode failure.The predicted service life of the traditional Ti/Sn O2-Sb electrode is 0.016 years.To improve the coating quality of electrodeposition prepared Ti/Sn O2-Sb electrode,strategies including deep eutectic solvent electrodeposition and stannous citrate complex treatment are proposed to reduce the coating defects,respectively during the electrodeposition and post-treatment process.The as-prepared electrodes respectively show 0.7and 1.5 times increased kinetic rate constant for methylene blue?MB?degradation,and 2.2 and10.9 times increased service lives.The predicted service lives of prepared electrodes are increased to 0.058 years and 0.23 years,respectively.Both the two strategies are facile,green and efficient.However,the service life of the prepared electrodes still cannot meet the application requirements.The low load capacity of the two-dimensional titanium sheet substrate and the low load efficiency of the traditional preparation methods are the key limiting factors of the electrode service life.To solve this problem,an innovative solvothermal preparation method was proposed and titanium foam is selected as the substrate to prepare a three-dimensional electrode named f-Ti/ATO-3D which has high catalysts loading,high stability and high electrochemical activity.This electrode performed 1.2 times increased rate constant for MB degradation and its predicted service life reached 1.57 years,which is about 98 times that of the traditional p-Ti/ATO electrode.Further,Ni doping was introduced and the as-prepared f-Ti/ATO-Ni electrode shows excellent OH·and O3production performance.The OH·production performance is better than the commercial boron-doped diamond electrode,and the coulombic efficiency for O3 production reaches 21%.The First-principles calculation results demonstrate that Ni-doping can increase the electronic density of states near the Fermi level of the doped Sb atoms,that improves the electrochemical activity of the electrode,and the overpotential for O3 production decreased from 2.79 e V to 0.89 e V,that contributes to the excellent O3production ability of Ni-doped electrode.In addition,Ni-doping increases the release energy of surface Sn,Sb atom of Sn O2-Sb,contributing to the higher stability of Ni-doped electrode.The predicted service life of f-Ti/ATO-Ni electrode reaches 17.6 years.It is the longest reported service life of antimony-doped tin dioxide electrode,that can meet the practical application requirments.To reduce the energy consumption of single advanced oxidation process for treating complex refractory organic wastewater,this article proposes three coupling strategies of advanced oxidation and biological method.?1?Using the developed high-efficiency and long-life anode to deeply treat the effluent discharged from the actual dyeing wastewater plant to meet the discharge standard of recyclable industrial water?GB/T19923-2005?,and the processing energy consumption is only 1.36 KWh m-3.Continuous flow operation in the sewage treatment plant for180 days,the performance remains stable.?2?Microbial fuel cell?MFC?and EAOPs are coupled to treat landfill leachate.The enhanced MFC process reduces the landfill leachate COD from an initial value of about 28742 mg L-1 to about 2192 mg L-1.Subsequently,the EAOPs process degrades COD below 200 mg L-1 with the processing energy consumption of about 85 KWh m-3.?3?Plasma oxidation process coupled with MFC is proposed for treating high concentration MB wastewater.With the plasma treated for 10 min,the BOD5/COD ratio of 300 mg L-1 MB wastewater increases from 0.04 to 0.38,and the inhibition rate on E.coli growth decreased from85.5%to 27.9%.The following MFC process increases the TOC removal efficiency from 23.2%to 63%.The mineralization energy consumption of the coupling process was 0.143 KWh g TOC-1,which was only 41.8%of the plasma oxidation process.The coupling strategies of advanced oxidation process and MFC can achieve high-efficiency treatment of refractory organic wastewater with reduced energy consumption. |
PDF Full Text Request