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.