| Poly (vinylidene fluoride)(PVDF) is widely used in membrane preparation because of itsoutstanding chemical, mechanical and thermal stability. Due to the low surface energy, whichleads to significant membrane fouling in membrane separation processes, PVDF membranes werelimited in application of water abd waste water treatment. At present, surface modification iswidely used in the membrane industry to improve the hydrophilicity of PVDF membranes toincrease its anti-fouling ability. The modification methods include blending, chemistry reaction,light grafting, and so on.In this paper, poly(ethylene glycol) methyl methacrylate (PEGMA), which containspolyethylene glycol (PEG) and carbonyl groups, was grafted on the hydrophobic surface of PVDFultrafiltration membranes via UV-irradiation, completing the surface hydrophilic modification.The addition of N,N-methylene bisacrylamide (MBAA) as cross-linking agent was testifiedeffective to reduce the swelling of coating layer, and UV-irradiation did not distroy the membranestructure. Moreover, the process of modification was of simplicity and low cost. This paperfocused on the effect of various modification conditions on the modified membrane perfomancethe antifouling ability which was testified by the filtration tests of emulsion oil solution and BSAsolution and the stability which was comfirmd by soaking the membrane samples in acid, alkaliand sodium hypochlorite solution.In this investigation, the modified sampleswere analyzed by fourier transform infraredspectroscopy (FTIR). The results confirmed that the PEGMA was successfully grafted on themembranes. The images from the field emission scanning electron microscopy (FESEM) showedthat pore size and porosity decreased. The hydrophilcity of PEGMA-grafted membrane wasenhanced according to contact angle (CA) measurement. The pure water flux of the modifiedmembrane declined with the addition of PEGMA concentration and grafted time The CAunmodified membrane was about77°under the condition of PEGMA concentration80g/L andgrafted time of60min, while it was about58°with PEGMA concentration40g/L and grafted timeof60min. The pure water flux of the unmodified membrane was184.9L/m2·h and162.2L/m2·h, respectively,. Water takeup of the modified membrane was increasing with the addition ofPEGMA and grafted time. On the contrary, the CA and the pure water flux slightly decreased withthe additive of MBAA. In filtration test of BSA solution, the rejection rate of the unmodifiedmembrane was lower than the modified membrane at first and higher than the modified ones in thenext stage.The filtration tests of emulsion oil solution and BSA solution were conducted to investigaedthe anti-fouling ability of the modified membranes. The results showed that the order of theanti-fouling ability was unmodified membrane <PEGMA+MBAA membrane <PEGMAmembrane. The permeability recovery of the membranes in oil emulsion filtration was less thanthat in BSA filtrtion. The stability of modified membrane was in the order of acidic aquatousenvironment, strong oxidizing aquatous environment, alkaline aqutous environment.This project research results can not only broden the preparation technology ofhigh-performance ultrafiltration, but also can provide related technical support for membranematerial explore, separation technology, membrane process operation and management. |
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