Preparation And Characterization Of Al₂O₃ Composite Hollow Fiber Membranes By Sol-Gel Method

In this paper polyether sulphone (PES)-titania (TiO2) composite ultrafiltration (UF) membranes were prepared by combination of the sol-gel method and phase separation method. Ceramic (Al2O3,TiO2) hollow fiber UF membranes were prepared by the sol-gel method and then through high heat sintering. The structure and properties of the UF membranes were systemically characterized by various test methods (SEM, flux, rejection, porosity and mechanical properties, etc.). And kinds of factors that effecte the properties of separating membranes were srudied theoretically.Firstly, Al2O3 sol and TiO2 sol were prepared by the Destabilization of Colloidal solution (DSC) and the Polymerization of Molecular Units (PMU) method respectively during the initial basic research period. The factors that effected the properties of the sol were studied with different ratio and aging conditions. And the technologcial conditions were set down for further research.Secondly, TiO2 sol was prepared with Tetrabutyl titanate (TBT) as precursor and dimethyl acetamide (DMAc) as solvent. Then the sol was added to the PES/DMAc/DegOH dopes. The composite hollow fiber UF were prepared by the non-solvent induced phase separation (NIPS) method. The viscosity of the dopes decreased firstly and then increased with the increment of TiO2 sol in dopes. And the microscopic structures of the membranes were mainly depending on the content of the TiO2 sol in the dopes. The addition of the sol particles improved the permeation flux of the membranes when the content of TBT was less than 3%. However, there would be no improvement of the properties of membrans if the content of TBT was more than 3%.Subsequently, TiO2 sol was prepared with TBT as precursor and diethylene glycol (DegOH) as solvent. Then the sol was added to the PES/DMAc dopes. The composite flat membranes were prepared by the VIPS-NIPS method. The dope viscosity increased with the increment of TiO2 sol.Finally, the Al2O3,TiO2 ceramic UF membranes were prepared with hollow fiber carriers by the dipping and drawing method. And the film effect of the granular pattern Al2O3 sol was good. The effective film was made through three times'coating. The rejection of BAS was over 90%. The addition of solvent had great effect on the film effect of the coating times would increase to achieve effective separation if the solvent addition was high, which might result in high cost of production.