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Abstract Bovine serum albumin (BSA) was selected to represent the organic foulant, and the adsorption behavior of BSA on PVDF membrane surface and the features of the changes of the structure of the adsorption layers change at different pH was investigated by the quartz crystal microbalance with dissipation monitoring (QCM-D), and the quantitative determination of the interaction forces between BSA-BSA and PVDF-BSA at relevant pH values were measured by atomic force microscope (AFM), and the mechanism of the influences of pH on the membrane fouling behaviors of organic foulant were analyzed combined with the membrane fouling experiment. According to the results, at the isoelectric point of BSA, there was the minimal value of the electrostatic repulsive forces between BSA-BSA and between PVDF-BSA, a higher deposition rate of BSA was resulted on the membrane surface, and a denser BSA layer was formed, so the flux was declined most severely. As pH deviated from the isoelectric point, the membrane fouling and the deposition rate of BSA onto the membrane surface were mitigated, which was mainly due to the increase of electrostatic repulsion forces, accompanied by a “loose” BSA layer was formed. Therefore, it is important to adjust pH to control the net charges of foulants and membranes positively or negatively to the same level together with the increase of the net charges of the both, because it is one of the effective strategies for mitigation of membrane fouling.
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Received: 11 May 2015
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