Novel method for treatment of hollow fiber membranes using hypochlorite

Abstract

A novel hypochlorite treatment method that enhances hydraulic permeability of hollow fiber membranes used in ultra-filtration was successfully devised and tested. Dope containing polysulfone/poly vinyl pyrrolidon (PVP-K90)/N-methyl-2-pyrrolidone (NMP) in mass ratio of 15:5:80, respectively, were used to produce hollow fibers via dry-jet wet spinning process. NMP in 1:1 ratio and distilled water were used as bore fluid. Hollow fiber membrane samples were post-treated using the novel, 95°C water and traditional hypochlorite treatments. State of membranes before and after post-treatment were morphologically compared using SEM microphotographs of fiber cross-section in conjuncton with image proceesing techniques. It was observed that in general both the novel and the traditional methods results in elimination of PVP swelling alone with alteration of pore size and pore distribution. This was confirmed by an increase in water flux of the hollow fibers that were subjected to these two post-treatment methods. Atomic force microscopy analysis vividly pointed to an intense increase in the roughness of the inner and outer surfaces of the membranes. This was attributed to the effect of post-treatment methods. It was found that in general post-treatments involving hypochlorite, increases the surface roughness of the membranes. However, increase in rate of the roughness of inner surface of traditionally hypochlorite treated hollow fiber membrane was found to be much higher than those subjected to the novel treatment method. It was established that the developed novel hypochlorite treatment method can be successfully used for production of high permeable hollow fiber membranes which have vast potential in therapeutic applications.