Explanation Of The Adsorption Mechanism Of Protein Adsorbed On Polymer Membranes By Surface Tension Components Theory

The pollution problem on the ultrafiltration membrane has been concerned in membrane separation field. It is necessary to establish an effective mechanism of membrane fouling theory to develop anti-fouling membranes. At present, the theory of hydrophilic-hydrophobic interaction was adopted to explain adsorption behavior between contamination and membrane. As this is one single parameter theory, it often can not accurately explain the behavior of membrane fouling. Thus it is necessary for unsing more accurate theory to analyze the membrane fouling mechanism. The surface tension components theory was considered to accurately explain surface and interface interaction of materials, but this theory has not been widely used for studying membrane fouling mechanism. And the surface tension components values of many polymer materials have not been determined. Therefore, in this dissertation, the surface tension components theory was used for researching the membrane fouling behavior. Bovine serum albumin was taken as the pollutants. Dynamic cycling contact angle technique was adopted to measure the surface tension components values of the polymer materials (PES,PBT,PEI,POM,PPO,PC,PSF,PVDF,SAR, etc.) and self-made ultrafiltration membranes (PES,PVDF and PSF). Egg white was blended with PES to fabricate the antifouling ultrafiltration membrane. The relationship between preparation conditions of fabricating membrane and membrane fouling has been investigated.The non-porous homogeneous films were fabricated from polymer materials. It was found that there were some relationships between the BSA adsorption amount, surface tensions of the polymer films and the interfacial tensions between the BSA and the polymers. When the Lifshitz-van der Waals force value of the polymers increased, the BSA adsorption amount increased. For the electron donor component value, increase of electron donor component value induced weak adsorption on the polymers for BSA. When the interfacial tension value between the polymer materials and BSA increased, the BSA adsorption amount increased. It has some relationships between surface tension components and the molecular structure of the polymer materials. For PBT,PC,PPO and POM, their structures contained the ether groups, consequently, their electron donor values were large. The position of benzene ring had a big influence on the adjacent group. Benzene ring could significantly reduce the electron donor-acceptor values of ether group. Therefore, the electron donor values of PEI, PES and PSF were small.The ultrafiltration membranes were fabricated from PES,PSF and PVDF. It was found that when the Lifshitz-van der Waals force value of ultrafiltration membrane increased, BSA adsorption amount on the ultrafiltration membrane increased. Increase of electron donor component values induced weak adsorption on the ultrafiltration membrane for BSA. When the interfacial tension values between ultrafiltration membrane and BSA increased, the BSA adsorption amount increased. On the whole, the adsorption behavior on the porous ultrafiltration membranes for BSA was similar with the adsorption behavior on the non-porous polymer materials for BSA.The egg white was blended with PES to modify the ultrafiltration membranes. The proper conditions of preparing the PES/EW membranes were:the concentration of PES in the casting solution was 18wt.%. The concentration of egg white in the casting solution was 4wt.%. The concentration of PEG in the casting solution was 10wt.%. The temperature of coagulation bath was 20℃, and the evaporating time was 10 seconds. The order from high to low for the antifouling performance of the blended membrane was:PES/EW (4wt.%)＞PES/EW (6wt. %)＞PES/EW (2wt.%)＞PES (pure). The flux attenuation coefficient value decreased from 52.36% for the PES/EW (4wt.%) membrane to 45.6% for the pure PES membrane. The adsorption behavior on the blended ultrafiltration membrane for BSA was similar with the adsorption behavior on the non-porous polymer materials for BSA.This research work will play an important role in systemically understanding the relationship between molecular structure and surface tension components for polymer materials, and it will also have a significant value for deeply understanding the relationship between polymer materials and membrane fouling from protein.