Preparation and characteristics of cross-linked cellulose acetate ultrafiltration membranes with high chemical resistance and mechanical strength

Cellulose acetate (CA) membranes, which are highly hydrophilic, have the advantage of being highly resistant to fouling phenomena and economically affordable. However, as material they pose the problem of low chemical resistance and mechanical strength. In this study, cross-linked cellulose acetate (CCA) was prepared using trimesoyl chloride (TMC) in order to overcome this material weakness. Cross-linking of CA was confirmed both directly and indirectly using FT-IR and viscosity of dope solution. In particular, viscosity of dope solution gradually increased as TMC concentration was increased, but rose sharply from 2.1 wt.%. CCA membranes thus prepared showed four times the tensile strength of existing CA membranes, and improved chemical resistance against polar solvents (ethanol, acetone, DMAc). The morphology of membranes was confirmed using SEM, and CCA membranes displayed more even pore size and dense cross-section than those of existing CA membranes. It was also shown that CCA membranes can also significantly reduce compaction phenomena, which may occur in the use of membranes, due to their improved mechanical property and dense structure. CCA membranes showed definite possibility for use in ultrafiltration (UF) by removing over 99.85% of kaolin.