Electrochemical Oxidation And Advanced Oxidation Processes For Organic Pollution Decomposition Coupled With Simultaneous CO₂ Conversion To Liquid Fuels

With the rapid economic development in past few decades,the discharge of wastewater and the emission of greenhouse gases have determined to be the most two serious environmental problems that humans are facing.Accordingly,extensive studies have focused on the oxidation of organic compounds in wastewaters into CO₂and the reduction of CO₂ into liquid fuels.Recently,Advanced oxidation processes?AOPs?are promising technologies to degrade organic compounds in aqueous media because they can generate highly reactive species such as·OH and SO₄^·-radicals that quickly oxidize a broad range of organic pollutants.On the other hand,Electrochemical oxidation?EO?is an excellent technology for organic pollutants degradation in wastewater owing to its high stability,high efficiency and easy to recycle.Despite great many reports on degradation of organic pollutants by AOPs or electrocatalysis,there are no reports on the coupling of organic pollutants degradation with AOPs and electrocatalysis in a catalytic system.In this article,we prepared novel anode materials based on transition metal oxides for construction of electrocatalytic coupled advanced oxidation processes system.In this system,the degradation efficiency of organic pollutants can be improved.Generally,the current of the cathode is not well utilized,which leads to the higher cost and less efficiency of the electrocatalytic treatment of organic pollutants.In order to save costs and improve efficiency,we proposed a new catalytic system,the current of the cathode is utilized to CO₂ reduction,so as to realize the efficient mineralization of organic pollutants in wastewater removal and resource recovery.Based on the this discussion,we prepared Co₃O₄ arrays or Co₃O₄@C arrays as anode for the electrocatalytic degradation of organic pollutants 4-NP,and flower-like CuO or nanosheet SnO₂ as cathode for the electrocatalytic CO₂ reduction.Firstly,we obtained a new 3D hexagonal Co₃O₄ array and flower CuO by hydrothermal method.Degradation of 4-NP by electrocatalysis and AOPs was carried out under potentiostatic conditions at room temperature?25°C?in H-type cell,while a as-prepared Co₃O₄ was used as the anode,and CuO was used as cathode for CO₂electroreduction.According to the experimental results revealed that the Co0.5 has higher removal efficiency for 4-NP,92%of 4-NP was degraded within 60 min in the PMS/Co0.5 system.In a electrocatalytic oxidation and AOPs system,nearly 100%of4-NP was degraded by the Co0.5/PMS system at different bias potentials after 60 min.In single CO₂ reduction system,the formation yield of CH₃OH and C₂H₅OH is up to125.8 and 22.22?mol/L,respectively,for 0.1 M KHCO₃ at-0.8 V and 120 minutes of reaction time.According to the experimental results that Catalytic degradation of4-NP coupled with electrocatalytic reduction of CO₂.The removal efficiency of 4-NP?>99%?,and the yield of CH₃OH and C₂H₅OH decreases,and the maximum yield of methanol and ethanol is 98.29?mol L^-11 and 40.95?mol L^-11 at-0.8 V after 120 min,respectively.Secondly,we try to combine carbon materials with 3D hexagonal Co₃O₄ in a composite system to obtain a new 3D hexagonal Co₃O₄@C array,we also obtained nanosheet SnO₂ by hydrothermal method.Degradation of 4-NP by electrocatalysis and AOPs was carried out under potentiostatic conditions at room temperature?25°C?in H-type cell,while a as-prepared Co₃O₄@C array was used as the anode,and SnO₂ was used as cathode for CO₂ electroreduction.According to the experimental results revealed that the Co0.5 has higher removal efficiency for 4-NP,74.5%of 4-NP was degraded within 60 min in the PMS/Co0.5 system.In a electrocatalytic oxidation and AOPs system,85.1%of 4-NP was degraded by the Co0.5@C/PMS system at different bias potentials after 60 min.According to the experimental results that Catalytic degradation of 4-NP coupled with electrocatalytic reduction of CO₂.The removal efficiency of 4-NP?>99%?,and the Faraday efficiency of HCOOH is 24.08%at-1.3 V after 120 min.Improving voltage to-1.5V,The removal efficiency of 4-NP?63.4%?,and the Faraday efficiency of HCOOH is 33.82%at-1.5 V after 120 min.Thirdly,we proposed a mechanism explain the electrocatalytic steps involved in the conversion of 4-NP to CO₂ and the synergetic effects between AOPs and electrocatalysis,as well as electrocatalytic oxidation and electrocatalytic reduction.These works provides an ideal scenario that couples the AOPs and electrocatalysis of organic pollutants with electrocatalytic reduction of CO₂ and opens a new avenue to realize the degradation and recycling of organic pollutants.