Preparation Of PVDF/PGS-g-PDMAEMA Composite Ultrafiltration Membrane

Poly(vinylidene fluoride)(PVDF)has been well known as a kind of promising membrane materials because of its excellent properties,and it is widely used in food,medicine,sewage treatment and other application fields.However,due to the low surface energy,the PVDF membrane has a strong hydrophobic performance.When they are applicated in aqueos systems,the organic matter is easily adsorbed to the membrane surfaces,thereby causing serious membrane fouling.To improve the anti-fouling and easy-cleaning properties,the nanofiber PGS-g-PDMAEMA(palygorskite-g-poly(N,N-dimethylaminoethyl methacrylate))was fabricated and was incorporated into PVDF matrix to prepare PVDF/PGS-g-PDMAEMA composite membranes.The PGS was surface modified with PDMAEMA by chemical grafting,and the influence of monomer amount on grafting rate was investigated.The BSA adsorption onto PGS-g-PDMAEMA with a graft ratio of 8.48%was less than that of PGS.The adsorption capacities were about 5.03 mg/g and 23.89 mg/g,respectively.The PVDF/PGS-g-PDMAEMA composite membranes were prepared by blending PGS-g-PDMAEMA with PVDF matrix.The mechanical strength,elongation and porosity were improved.Experimental results show that the defect holes of composite membrane were less than that of the original one.When the additive amount of PGS-g-PDMAEMA is 1 wt.%,the composite membrane had the narrowest pore size distribution,and the minimum contact angle at about 75.8°.The antifouling performance was investigated by using BSA solution as the evaluation system.The BSA static adsorption on the modified membrane was lower than that of the original one.The minimum adsorption amount was only about 256.06 μg/cm2.During the filtration of BSA solution,the permeate fluxes of the modified PVDF membranes were much higher and declined more slowly than that of the pristine one.When the additive amount of PGS-g-PDMAEMA is 1 wt.%,the membrane rejection reached 100%,and the stable permeation flux of BSA was 17.92 L·m-2h-1.Moreover,the modified membrane with 1 wt.%dosage had the highest flux recovery rate(about 54.17%)and exhibited excellent antifouling and easy-cleaning performance.