Effect Of Capacitive Deionization MXenes Electrodes On The Removal Of Copper Ions From Water

With the rapid development of industrialization,the chemical company has a heavy metal wastewater treatment problem.During the production of acrylamide,a large amount of divalent copper ions is dissolved in the wastewater due to the oxidation of catalyst copper,and the concentration of copper ions reaches 20～100mg/L,far exceeding the discharge standard of 0.5 mg/L.It is urgent to find removal technology to solve the actual discharge problem.Capacitive deionization technology（CDI）is considered a promising method for removing charged ions from aqueous solutions due to the advantages of environmental friendliness,high energy efficiency and easy regeneration of electrodes.The selection of an inexpensive electrode material with good performance has been a hot research topic in the application of CDI technology.MXenes,a two-dimensional nanomaterial with a unique layered structure,has attracted great attention from the materials science community because of its good electrical conductivity,hydrophilicity,high specific surface area,large layer spacing,and fast ion embedding and de-embedding.Therefore,this study systematically investigated the application performance of Ti₃C₂T_x MXenes in CDI system with Cu²⁺in water as the indicator pollutant and Ti₃C₂T_x MXenes as the cathode and anode of the capacitive deionization system,in order to provide a reference for the related research of Ti₃C₂T_x MXenes in CDI system.The research in this thesis includes three main aspects as follows.（1）Preparation and condition optimization of capacitive deionization electrode.The electrodes were assembled into CDI modules by preparing different material combinations and different coating qualities,and the adsorption tests were carried out with 50 m L of Cu SO₄ solution with an initial concentration of 20mg/L as the treated object.The adsorption capacity of Ti₃C₂T_x MXenes as both cathode and anode of the capacitive deionization module was found to be up to 4.9 mg/g at a coating mass of 160 mg.The Cu²⁺removal efficiency was 79.0%at a voltage of 0.8 V,a circulation flow rate of 10 m L/min and a p H of 4.0.（2）Influence factor optimization test.The main influencing factors and optimal conditions for the adsorption of Cu²⁺by Ti₃C₂T_x MXenes capacitive deionization system were determined by the test.The effects of adsorption time,initial concentration,applied voltage,circulation rate and p H on the adsorption performance were investigated sequentially for one-way analysis.The test was conducted with 50 m L of Cu SO₄ solution,with 0.8 V voltage,initial concentration of 20.0 mg/L,circulation rate of 10.0 m L/min and p H of 4.0 as the initial conditions.The best experimental operating conditions for Cu²⁺removal were finally obtained:adsorption time of 360 min,initial concentration of 100 mg/L,working voltage of 1.0 V,and circulation rate of 25.0 m L/min,at which the electroabsorption capacity of Cu²⁺was 49.4 mg/g and the removal rate was 98.6%.The Ti₃C₂T_x MXenes-based electrode was found to be suitable for a relatively wide p H range（3.0～5.0）.the Ti₃C₂T_x MXenes-based electrode had good stability after three electrosorption-desorption cycle tests,indicating that the electrode has good cycle reversibility performance.The real Cu-containing wastewater samples were studied by electrosorption under optimal adsorption conditions,and the Cu²⁺removal efficiency was 97.7%.（3）Characterization and mechanistic study of capacitive deionized MXenes electrodes.In order to investigate the mechanism of Cu²⁺adsorption by Ti₃C₂T_x MXenes-based electrodes,the physical and chemical properties as well as the electrochemical properties of Ti₃C₂T_x MXenes-based electrodes before and after Cu²⁺adsorption were characterized by SEM,TEM,XPS,BET,CV and GCD.The results showed that the organ-like layer structure of Ti₃C₂T_x MXenes provided effective channels and attachment sites for adsorption,while a portion of Cu²⁺was oxidized to Cu⁺ions on the surface of Ti₃C₂T_x MXenes-based electrodes after saturation of adsorbed Cu²⁺.The adsorption mechanism was determined as capacitive electroadsorption（double layer and pseudocapacitance synergy）and cathodic electrodeposition.It provides theoretical guidance for the application of MXenes in electrochemical removal of heavy metal ions in water.