Research On The New Organic Silicon Coating Modifird PVDF Membrane And Its Anti-fouling Performance

Membrane filtration has the advantages of low energy consumption,short treatment time,high efficiency,and simple operation.It is widely regarded as one of the most effective methods for treating water and various wastewater.However,one of the main challenges faced by membrane technology is the negative impact of membrane fouling.In particular,irreversible pollution caused by biological and organic pollutants may cause a significant drop in permeation flux and separation efficiency.In addition,irreversible membrane fouling hinders the effective recovery of these membranes by common cleaning methods,greatly increasing costs and limiting the applicability of membrane separation techniques in practice.In this study,based on a simple sol-gel flow-through coating process and the antipollution properties of zwitterions,a new membrane modification strategy was proposed.To this end,a new zwitterionic siloxane precursor was synthesized.The effects of reaction temperature,raw material ratio and reaction time on the synthesis products were studied,and then the optimal synthesis conditions were determined.On this basis,the membrane is modified with zwitterionic silicone by sol-gel method to give the membrane surface anti-pollution performance and anti-protein and E.coli adhesion performance,namely PVDF-POSS-SO3 H and PVDF-POSS-COOH.The chemical changes of the modified film surface were analyzed by Fourier transform infrared spectroscopy(FTIR),EDX(energy dispersive X-ray spectroscopy),XPS(Xray photoelectron spectroscopy).It is proved that zwitterions are successfully introduced into the membrane surface.The hydrophilic and hydrophobic properties of the membrane surface before and after modification were determined by a contact angle measuring instrument.The influence of different coating amount,membrane surface composition,electrical neutrality,hydrophilicity and hydration ability on the antifouling ability of the film was determined.The bovine serum protein adsorption and E.coli adhesion experiments,as well as the dynamic filtration experiments of BSA(bovine serum albumin)and SA(sodium alginate),proved that the modified two zwitterionic membranes have good anti-pollution performance and excellent antibacterial properties.Studies comparing sulfonic acid zwitterionic membranes and carboxylic acid zwitterionic membranes have shown the performance of PVDF-POSS-SO3 H membrane is better than PVDF-POSS-COOH membrane.First,both membranes have good hydrophilic properties and water absorption properties.The contact angles of PVDF-POSS-SO3 H membrane and PVDF-POSS-COOH membrane are 32° and 40°,respectively.The water absorption rate is 240% and 180% respectively.The experimental results of anti-protein adsorption experiments show that even a slight charge bias on the surface of the zwitterionic membrane can induce electrostatic interaction between the protein and the membrane surface,resulting in surface protein adsorption.The dynamic filtration test results show that the optimized PVDF-POSSSO3 H membrane has excellent long-term anti-pollution ability for proteins and polysaccharides.In the BSA and SA flux tests,the FRR values of the original PVDF were 18.6% and 23.5%,respectively,and the FRR values of the PVDF-POSS-SO3 H membrane were 86.32% and 94.9%,respectively.The FRR values of the PVDF-POSSCOOH film are 74.76% and 85.88%,respectively.Both membranes on the surface of E.coli adsorption test and dynamic filtration test have good antibacterial adhesion properties.In addition,the coating stability results show that zwitterionic membranes have good solvent-resistant cleaning stability and excellent mechanical stability.In addition,PVDF-POSS-SO3 H membrane has better acid stability.