Study On The Protein Adsorption Of Functionalized Nanoparticles TiO₂/PVDF Composite Membranes

TiO2 nanoparticles were widely used as food additives and cosmetic, which shows good biocompatibility and bonding biological activity of the protein. Polyvinylidend fluoride (PVDF) membrane has the strong hydrophobicity and stable chemical feature, but it is more easily to be polluted when used for the separation or purification of protein and protease, and the selectivity of the membrance needs to improve. The oleic acid (OA) was used to modify TiO2 nanoparticals and enhance bind ability with the organic molucalars. The functionalization OA/TiO2 nanoparticles were bleded with PVDF and OA/TiO2/PVDF composite membranes were prepared, which were used in the protein separation research. The OA/TiO2/PVDF composite membranes combined the advantage properties of nanoparticles and polymer’s excellent characteristics, which might have excellent adsorption performances in the field of protein adsorption separation.In the sol-gel process of TiO2, the OA was added in the TiO2 sol-gel and OA/TiO2 functionalized nanoparticles were prepared. Then, the OA/TiO2 nanoparticles were used in the adsorption experiments of bovine hemoglobin (HB) and bovine serum albumin (BSA). The results showed that, compared with original nano-TiO2,OA/TiO2 nanoparticles show significantly improved adsorption capacity of HB, and decreased adsorption capacity of BSA. Under the optimal conditions:the initial concentration of the protein is 150 μg·mL-1, OA/TiO2 dosage is 0.8 mg·mL-1, absorption time is 80 min (HB) or 100 min (BSA), the pH value is 6 (HB) or 5 (BSA), the maximum adsorption capacity of HB is 180 mg·g-1, while of BSA, is 34.43 mg·g-1.The blend membranes of OA/TiO2/PVDF were prepared. Some means such as SEM, XRD, TG-DTA, FT-IR and contact angle measurement were used to character the composite membranes. The results of adsorption experiments showed that, compared with TiO2/PVDF membranes, the OA/TiO2/PVDF composite membranes have enhanced adsorption activity toward HB and decreased adsorption activity toward BSA. Under the optimal conditions:the initial protein concentration is 150 μg·mL-1, contact time is 70-90 min, concentration of NaCl is 0.20 mol·L-1, the pH value is 6 (HB) or 4 (BSA), the loading amount of OA/TiO2 is 8 wt %, the maximum adsorption percent of HB is 100%, while which of BSA is 36.8%; the maximum adsorption capacity of HB is 146.38 μg·cm-2 and of BSA is 47.5 μg·cm-2. Finally, the adsorption isotherms and kinetics model of the process were discussed too.