Preparation Of Polypyrrole Composites By Electrodeposition And Its Application In Capacitive Deionization Technology

In recent years,capacitive deionization（CDI）technology,as a new technology that is easy to operate,environmentally friendly and recyclable,has become one of the ways to solve the problems of heavy metal wastewater pollution.At present,the research core of CDI technology is still high-performance electrode materials Of preparation.Polypyrrole（PPy）is a common conductive polymer.It has the advantages of high specific capacitance,low cost,and good chemical stability.PPy can prepare electrode materials with excellent performance by compounding with carbon materials and metal oxides,and has good application prospects in CDI technology.In this paper,the PPy composite electrode was prepared by electrodeposition.The effect of the electrodeposition process and the addition of components（chitosan,graphene oxide,and manganese dioxide）on the surface characteristics,electrochemical performance,and adsorption performance of the composite electrode was explored.Preparation process parameters of PPy composite electrode with adsorption performance.This thesis mainly includes the following:（1）PPy/CS/GO composites with sandwich structure were successfully prepared by layered electrochemical deposition,and their morphology and structure were studied.PPy and CS were spherical and surrounded by GO sheets.Chemical bonds are bonded to each other.The electrochemical characteristics and adsorption/desorption properties of PPy/CS/GO composites were tested and analyzed.The results show that compared with PPy electrodes,PPy/CS/GO composite electrodes have higher capacitance（165.03F/g）and lower charge transfer resistance（1.959Ω·cm²）.The adsorption capacity of the PPy/CS/GO composite electrode is35.53 mg/g,which is about 2.03 times（17.46mg/g）of the PPy electrode.After 5adsorption/desorption processes,the adsorption capacity remains at 96%.（2）PPy/GO composite material was successfully prepared by anode electrochemical co-deposition method,and its morphology and structure were studied.The PPy/GO composite exhibits a dense sheet structure,and PPy is spherical and evenly distributed on the GO sheet.The electrochemical characteristics and adsorption/desorption performance of PPy/GO composites were tested and analyzed.The results show that PPy/GO electrode has higher capacitance（186.67F/g）and lower charge transfer resistance（1.626Ω·cm²）than PPy electrode.The adsorption capacity of PPy/GO electrode for Cu²⁺reached 41.51mg/g.After 5 adsorption/desorption processes,the adsorption capacity was maintained at 98%,which could indicate good cycle stability.In addition,the adsorption capacity for different metal ions is:Ag⁺<Cd²⁺<Cu²⁺<Pb²⁺<Fe³⁺.（3）PPy/GO/MnO₂ nanocomposites were successfully prepared by anode electrochemical co-deposition,and their morphology and structure were studied.PPy encapsulates MnO₂ nanoparticles and distributes them evenly in the GO sheet.Electrochemical test results show that PPy/GO/MnO₂ nanocomposites have a specific capacitance of 376.58F/g,a charge transfer resistance of 0.8435Ω·cm²,and excellent electrochemical performance.The adsorption test results show that the PPy/GO/MnO₂nanocomposite electrode has an adsorption capacity of 36.77 mg/g.After 5adsorptions/desorptions,the adsorption capacity remains at 99%,and after 10adsorptions/desorptions,the adsorption capacity remains At 97%.The adsorption kinetics of PPy/GO/MnO₂ nanocomposite electrode for Cd²⁺,Cu²⁺and Pb²⁺is in line with the quasi-secondary model,and the adsorption method is chemisorption.The isothermal adsorption model is more in line with the Freundlich model.