MBfR中PVDF／pDOPA改性膜耐污染性能研究

Anti-fouling Property of PVDF/pDOPA Modified Membrane for MBfR

针对膜生物膜反应器(MBf R)研究中疏水性微孔膜供氧能力不足、耐污染性较差等问题,采用自聚合法对自制疏水性聚偏氟乙烯(PVDF)中空纤维膜进行表面改性,研究制备适用于MBf R技术的PVDF/p DOPA中空纤维复合膜。选取典型有机污染物牛血清白蛋白(BSA),考察原膜及表面改性膜的抗污染性能,并采用XDLVO理论定量解析BSA对PVDF原膜及PVDF/p DOPA改性膜的污染行为。研究结果表明,改性膜对BSA的吸附速率低于原膜,最终BSA吸附量为原膜的62.1%,进一步的氧传质实验表明BSA污染后,改性膜的氧总转移系数衰减率(14.0%)低于原膜(21.9%),显示出优于原膜的抗污染性能。XDLVO理论所涉及到的三种界面自由能中,粘附阶段和粘聚阶段的极性力界面自由能均起主导作用,决定总界面自由能的性质,范德华力界面自由能和静电力界面自由能绝对值相对较小,对膜污染影响较为微弱;PVDF/p DOPA改性膜与BSA之间的总表面自由能(10.53 m J/m2)远大于PVDF原膜(-12.52 m J/m2),较好的解释了原膜与改性膜耐污染性能的差异。

Aiming at the shortcomings of hydrophobic PVDF hollow fiber microporous membrane, such as insufficient oxygen supply capacity and poor antifouling property, surface modified composite membrane was prepared used self-made hydrophobic PVDF hollow fiber membrane by the method of L-DOPA self-polymerization for MBfR technology. Bovine serum albumin （BSA） was selected as a typical organic pollutant to evaluate anti-pollution ability of PVDF original membrane and PVDF/pDOPA modified membrane. Results showed that, the adsorption capacity of modified membrane was less than that of original one, and its BSA adsorption quantity was 62.1% of original membrane. The further oxygen mass transfer experiments showed that the total oxygen transfer coefficient attenuation rates of the modified membrane （14.0%） was lower than that of the original one （21.9%） after BSA pollution, which indicated that anti-fouling capability of modified membrane was better than that of the original one. And the extended Derjaguin Landau Verwey Overbeek （XDLVO） approaeh was applied for better understanding of the contamination behavior of PVDF original membrane and PVDF/pDOPA modified membrane. During the adhesive and the cohesive stage, acid base interfacial free energy played a dominant role in determining the nature of the total interfacial free energy, Van der Waals forces interracial free energy and static electricity interracial free energy were relatively small, less impacting membrane fouling. The difference between the total interfacial free energy of the modified membrane and original membrane （10.53 mJ/m^2 and -12.52 mJ/m^2） was consistent with membrane pollution trend of BSA adsorption experiment, the XDLVO theory could reasonably predict BSA fouling behavior of PVDF/pDOPA modified membrane.