Modifying PVDF-g-PSSA Proton Exchange Membrane By Doping With SGO@SiO₂ And Its Property In Microbial Fuel Cells

As an important part of microbial fuel cells,proton exchange membranes directly affect the battery's electricity production efficiency and sewage purification results.Due to the working environment of the proton exchange membrane,the proton exchange membrane needs to meet the requirements of low cost,good hydrophilicity,high mechanical strength,high temperature resistance,corrosion resistance and high pollution resistance.The proton exchange membrane used in the market is a Nafion membrane,but the membrane has high preparation cost,high fluorine content,and easily to pollute the environment after degradation.Therefore,it is considered to replace the Nafion membrane with a membrane material PVDF which is relatively inexpensive and has high mechanical strength,stable chemical properties,and good thermal stability.Due to the hydrophobic nature of the PVDF material,it does not meet the requirements of the MFC system for the hydrophilicity of the PEM.It is therefore necessary to modify the PVDF membrane material to obtain a proton exchange membrane that meets the requirements.?1?In order to improve the comprehensive performance of proton exchange membrane?PEM?in microbial fuel cells,the SiO₂ was interspersed into sulfonated graphene oxide?SGO?by in situ hydrolysis using ethyl orthosilicate to obtain hydrophilic three-dimensional nano-particle SGO@SiO₂.The hybridized particles were characterized by TEM,FTIR,XRD,Raman,and BET to determine the preparation of SGO@SiO₂ was successful.?2?A new composite proton exchange membrane SGO@SiO₂/PVDF-g-PSSA was prepared by blending SGO@SiO₂ with self-made PVDF-g-PSSA homopolymer.The effects of different SGO@SiO₂ particleaddition percentage on the physicochemical properties and anti-contamination properties of the composite membrane were investigated.The crystallinity of the membrane material was measured by XRD.The roughness of the membrane surface was analyzed by AFM.The membrane section was characterized by SEM.It is concluded that when the addition amount of SGO@SiO₂particles is 1.0%,the hydrophilic contact angle of the composite proton exchange membrane is reduced by 22%,the water content is increased by 40%,the swelling ratio is increased by 28%,the breaking strength is increased to 37.3 MPa,and the IEC is reached.2.2 mmol/g,the proton conductivity increased to 0.069 S/cm,and the oxygen permeability decreased to 0.02 mg/?L·m²·d?,that is,the comprehensive physical and chemical properties of the composite membrane were optimized.?3?The contamination resistance of the membrane was analyzed by QCM-D technology.The results of QCM-D showed that the adsorption of BSA on the composite membrane was weak in pure water,the structure of the contaminated layer was loose,and the anti-pollution ability of the membrane was enhanced.The main reason is that the performance of the composite film incorporating hydrophilic SGO@SiO₂ composite particles is affected by both SiO₂ and SGO.The introduction of-SO₃H in SGO improves the proton conductivity of the composite membrane.The hydrophilic-SO₃H increases the water content of the composite membrane,while the higher specific surface area of?SGO is beneficial to the agglomeration between the dispersed inorganic particles SiO₂.The introduction of SiO₂ can improve the moisture retention of the composite membrane,inhibit the swelling of the membrane,and enhance the mechanical strength and anti-pollution ability of the composite membrane.However,when the amount of the composite particles added exceeds 1.0%,the overall performance of the composite proton exchange membrane deteriorates due to the presence of the"steric effect"of the particles.?4?The MFC system using 1.0%SGO@SiO₂/PVDF-g-PSSA membrane has good performance in terms of electricity generation performance and COD removal rate,the maximum power density is 185 mW/m²,the internal resistance is 152?,and the COD?5?removal rate is 75%.The CE value is 8.1%.Compared with the performance of the commercial Nafion-117 membrane,the composite membrane has improved physical and chemical properties,so it is expected to replace the high cost Nafion-117membrane.