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

摘要:

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.

Abstract:

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.