Ca2+对SiO2-BSA混合体系膜污染行为的影响

Effect of Ca2+ on membrane fouling in SiO2-BSA mixture

为研究Ca2+对SiO2-BSA混合污染物膜污染行为的影响,针对SiO2与牛血清蛋白(BSA)共存体系,在不同Ca2+浓度下,使用原子力显微镜测定各污染物与聚偏氟乙烯(PVDF)超滤膜及各污染物之间的作用力,结合膜污染实验,探讨Ca2+对SiO2-BSA混合污染物膜污染行为的影响.结果表明:随着Ca2+浓度的增大,SiO2-BSA引起的膜污染逐渐减小,主要是因为Ca2+改变了SiO2-BSA混合体系中各污染物与膜及污染物之间的相互作用力.针对污染物与膜之间的相互作用力,Ca2+的加入触发了PVDF膜与BSA及SiO2之间的水合排斥力,从而削弱BSA在膜表面的吸附累计速率,有效减缓了运行初期的膜污染速率;针对污染物之间的作用力,Ca2+浓度的增加使得SiO2-SiO2及SiO2-BSA之间作用力增大,从而导致污染物团聚形成大尺寸聚集体,在膜面形成松散多孔的污染层,进而伴随着膜污染速率以及污染幅度的减小.

To analyze the effect of Ca2+ions on the membrane fouling behavior in the mixture of SiO2 and bovine serum albumin(BSA),atomic force microscope(AFM)technique was used to measure the interaction between foulant-membrane and foulant-foulant under different Ca2+ion contents.Combined with PVDF membrane fouling and cleaning experiments,effects of Ca2+ions on the membrane fouling behavior in the mixed SiO2-BSA system were investigated.Results showed that with the increase of Ca2+ion content,the membrane fouling caused by SiO2-BSA gradually decreased,owing to that the Ca2+ions changed the interaction between the foulant-membrane and the foulant-foulant.The addition of the Ca2+ions could effectively trigger the hydration repulsion between PVDF membrane and BSA or SiO2,which weakened the adsorption rate of BSA on the surface of PVDF and ultimately reduced the membrane fouling rate at the initial stage of operation.As the Ca2+ion content increased,the interaction force between SiO2-SiO2 and SiO2-BSA increased,resulting in the formation of large aggregates and a loose porous fouling layer on the surface of the membrane,accompanied by minor membrane fouling.