Preparation Of Ion Exchange Polymer Modified Electrodes And Its Performance For Removing Of Fluoride From Water By Capacitive Deionization

The high fluoride groundwater is widely distributed in northern China.The rural areas are restricted by economic level and water treatment conditions,so the health and safety problems of drinking water need to be solved urgently.Capacitive Deionization（CDI）is a water treatment technology based on electric double layer capacitance theory and adsorption theory.It has the advantages of low energy consumption,high energy efficiency,easy regeneration,low cost,and environmental protection.Developing electrode materials and optimizing device structure are hot research directions in the field of CDI research.This paper started from the direction of electrode material,through the Sulfonated polyp Henylene oxide（SPPO）and quaternized polysulfone（QAPSF）composite electrodes were prepared by electrospinning technology using membrane capacitor deionization technology.A series of studies were carried out to compare the performance of the SPPO and QAPSF composite electrode with the conventional MCDI.In this subject,Polyp Henylene oxide and polysulfone were used as raw materials,SPPO and QAPSF were respectively prepared by sulfonation and quaternized amination which were used to prepare ion exchange electrode.At the same time,it had been characterized,including scanning electron microscope SEM test,infrared spectrum analysis,XPS,TGA,BET,contact angle test,CV cyclic voltammetry,EIS test analysis.The surface morp Hology,element composition,thermal stability,specific surface area and pore size,hydrop Hilic and electrochemical properties of the electrode materials were systematically investigated.The study found that the electrode modified by electrospinning technology was successfully attached to SPPO and QAPSF.The hydrop Hilic performance and capacitance structure of the electrode had been greatly improved.The contact angle of the prepared electrode was reduced from 132°of the raw material to about 110°.Although the specific surface area and pore size were smaller due to the coverage of ion exchange polymers,the structure were compact and the CV curve integral area were larger than that of raw materials.It showed that the capacitance of SPPO/QAPSF electrode were larger,and the analog double-layer capacitor composed of SPPO/QAPSF electrode had better conductivity and good double-layer structure.At the same time,SPPO/QAPSF electrode had excellent thermal stability,and its ion exchange membrane was below 100℃with almost no mass loss,which met the requirements of the process.In order to better study the performance of the SPPO/QAPSF electrode,it was compared with the conventional MCDI device to investigate the desalination performance.The optimal operating parameters of the electrode preparation process were determined to be the voltage of 1.2 V,the hydraulic retention time of 45 s,and the initial concentration of the solution 50 mg/L.Among the single anions,nitrate had the greatest interference to the removal of fluoride ion,and the removal rate of fluoride ion was about 30%.Adsorption effect in mixed anions:NO₃^->SO₄^2->Cl^->F^-,the removal effect of monovalent anions had been greatly improved.The simulated groundwater distribution experiment showed that both devices preferentially adsorbed F^-and NO₃^-,and the SPPO/QAPSF composite electrode electro-adsorption device had a better removal effect.The removal rate of F^-and NO₃^-in the composite electrode electrosorption device was twice that of the conventional MCDI device,and the removal rate of Cl^-and SO₄^2-was also much higher than that of the conventional MCDI device.In the application of the SPPO/QAPSF composite electrode electro-adsorption device had certain practical application significance in the application of groundwater quality.