Modification And Properties Of SGO/PVDF-g-PSSA Proton Exchange Membrane

With the depletion of fossil fuels,climate change and environmental pollution have been rapidly increasing,many researchers have devoted to develop new environmentally friendly energy sources.In recent years,microbial fuel cells(MFCs)have attracted widespread attention as potential technologies for generating clean energy and additional advantages in bioremediation,particularly,the organic waste in wastewater has been degraded by microbial metabolism to obtain energy.The proton exchange membranes have become an indispensable part of MFC,and its comprehensive performance have a direct impact on the electricity production efficiency of the entire MFC system.Therefore,the preparation of a proton exchange membrane with high efficiency and low performance have become an important measure to improve the electricity production performance of the MFC system.In this research,SGO/PVDF-g-PSSA(abbreviated as SGO/PSSA)composite proton exchange membrane was prepared by mixing sulfonated graphene oxide(SGO)with polyvinylidene fluoride grafted styrene sulfonic acid(PVDF-g-PSSA).The physicochemical properties,structural characteristics and anti-membrane pollution properties of the composite membranes with different amounts of SGO were studied.The main results are as follows:(1)The surface structure and microscopic morphology of GO and SGO were determined by Fourier diffuse reflectance infrared spectroscopy(FTIR),X-ray diffractometry(XRD),transmission electron microscopy(TEM)and X-ray photoelectron spectroscopy(XPS),which confirmed that GO was successfully sulfonated into SGO.The prepared SGO particles were doped into PVDF-g-PSSA homopolymer,and the new modified composite proton exchange membranes of SGO/PSSA were successfully prepared by solvent evaporation method.(2)The physicochemical properties such as hydrophilicity,proton conductivity,ion exchange capacity and mechanical properties of the composite membranes with different SGO additions were tested.The results showed that the SGO addition amount increased from 0% to 1.0%,the overall performance of the SGO/PSSA composite film was significantly improved.The 1.0% SGO/PSSA composite membrane had the highest water content(44.34%),proton conductivity(0.085 S/cm)and ion exchange capacity(1.25 mmol/g),because the sulfonic acid groups introduced by SGO have provided a smoother ion channel for proton transfer,while the-OH in SGO was replaced by a more hydrophilic sulfonic acid group,enhancing the hydrophilicity of the composite membrane and providing more transport carrier,Grotthuss and Vehicle mechanism synergistically have enhanced the proton conductivity of the composite membrane.However,when the SGO doping amount exceeded 1.0%,the water content and proton conductivity of the composite membrane decreased,which was due to the effect of the "steric hindrance".(3)The surface functional groups,morphology and crystal morphology of the composite membrane were characterized by FTIR,SEM and XRD.It was detected that the 1.0% SGO/PSSA composite membrane newly appeared C=O group in the FTIR chart,the surface and cross-section morphology were relatively uniform in the SEM image,and the crystallinity in the XRD pattern was the lowest,indicating that the 1.0%SGO/PSSA composite membrane has a good microstructure.(4)The dissipative quartz crystal microbalance(QCM-D)was used to analyzed the anti-pollution performance and mechanism of the composite membrane in pure water and 50 m M PBS.The results showed that the adsorption of BSA on the surface of 1.0%SGO/PSSA composite membrane was the least,and the structure of the adsorption layer was loose,because a hydrogen bond network structure was easily formed by the functional group in the SGO particles and the sulfonic acid group in the PVDF-g-PSSA homopolymer,and the water molecules easily entered the inside of the adsorption layer to make the adsorption layer more loose.Under the condition of 50 m M PBS,the surface of the composite membrane showed a larger adsorption amount,because the enhancement of the ionic strength enhanced the action of the compressed electric double layer,resulting in a decrease in the charge of the membrane surface and BSA,thereby reducing the electrostatic repulsion between the membrane surface and BSA,and BSA and BSA,which caused the deposition of BSA on the surface of the membrane.(5)Using sodium acetate as the substrate,1.0% SGO/PSSA composite membrane,1.0% GO/PSSA composite membrane and Nafion membrane were used as the separation materials of MFC,and the electricity production performance of MFC was investigated.The study found that 1.0% SGO/PSSA membrane had the highest maximum power density,minimum internal resistance and COD removal rate.And after running MFC for three months,the system of SGO/PSSA composite membrane showed the lowest maximum power reduction rate,the smallest internal resistance increase rate and the smaller COD removal reduction rate,which were compared with the other two composite membranes.It showed that SGO/PSSA composite membrane had better anti-pollution ability.