STUDIES ON HYDROPHILIC POLYSULFONE ULTRAFILTRATION MEMBRANES

Ultrafiltration membranes were produced from carboxylated polysulfone polymers having different degrees of substitution (DS). Solute separation was found to increase with increasing DS. The techniques of single solute permeation and permoporometry were used to determine the pore size of these membranes. Permoporometry measurements indicated that pore size decreased with increasing DS. Solute separation was predicted by inserting the distribution of pore sizes obtained from permoporometry into a restricted transport model. Similar results were obtained from a nonlinear least squares fit of the restricted transport model to the experimental data. Both techniques produced similar sieving curves. It was concluded that pore size decreases were not due to the increasing repulsion of solute molecules by hydrophilic polysulfone but to changes in polymer solution properties as the DS increased.