典型一价阳离子对蛋白质膜污染的影响特性

Effect of monovalent cations on ultrafiltration membrane fouling of protein

通过耗散型石英晶体微天平结合自制的聚偏氟乙烯(PVDF)芯片,考察离子强度为0mmol/L及Li Cl、Na Cl、KCl离子强度为100mmol/L条件下,牛血清蛋白(BSA)在PVDF界面的微观吸附过程及吸附层结构特征,结合宏观膜污染及膜性能恢复试验,从微观角度阐述了膜污染过程中离子水合作用的产生过程及其影响因素,进一步解析了一价阳离子对超滤膜蛋白质污染行为的影响机制.结果表明:与离子强度为0mmol/L时相比,无论是Li^+、Na^+或K^+离子的存在,皆可有效触发PVDF-BSA及BSA-BSA之间的水合排斥力,进而减缓BSA在PVDF膜面的吸附累积速率,形成松散的BSA吸附层,相应膜污染减缓.但是Li^+、Na^+及K^+3种阳离子对膜污染的缓减幅度并不相同,离子半径越小,BSA在膜面的吸附累积速率越慢,吸附层越松散,相应膜不可逆污染越小,说明膜污染幅度与离子半径成正相关关系,这主要是因为上述3种阳离子所产生的水合排斥力不同所致.

A quartz crystal microbalance with dissipation monitoring(QCM-D)combined with a self-made PVDF-coated sensor crystal was used to investigate the deposition and adsorption behavior of BSA on the PVDF surface and the structure of the BSA adsorption the layers at ionic strengths of0and100mmol/L,of LiCl,NaCl,KCl.These results were combined with t fouling experiments and the flux recovery rate(at corresponding ionic strengths)to give a deep insight into the effect mechanism of monovalent cation on protein fouling of ultrafiltration membrane.The cause and influence factors of the action of hydrated ion in the process of pollution were described in a microcosmic view.Results showed that,compared with ionic strength0mmol/L,the hydration repulsive forces between PVDF membrane and BSA or between BSA and BSA could produce effectively by Li+,Na+or K+,which leading to decrease in the adsorption amount and rate of BSA on PVDF surface,more nonrigid and soft BSA layer was formed and accompanied by a decrease in membrane fouling.However,membrane fouling rate were different at Li+,Na+and K+environment.The smaller radiu of ion,the slower adsorption rate of BSA on PVDF surface,the more loosely BSA layer was formed,and lesser membrane fouling was occured.These results indicated that there was a positive relationship between membrane fouling rate and the sizes ofions,which mainly due to the difference of hydrated ability of Li+,Na+and K+.