Synopsis
Nylon-6-grafted polyacrylamide (NYgAM) membranes were modified by crosslinking and/or annealing with 65% aqueous solution of formic acid at room temperature. The permselectivity properties of the treated NYgAM membranes to a number of ionic solutes of varying molecular size ranging from HBr to tetrabutylammoniumbromide (Bu,NBr) were studied in the temperature range of 27-47OC. The temperature dependence of the permeation coefficients through the cross linked membranes indicates an apparent energy of activation of 6.6 and 11.3 kcal/mol for HBr and Bu,NBr, respectively. In the crosslinked and annealed membranes the corresponding activation energy values were found to range from 4.4, to 5.6 kcal/mol, reflecting the increased water uptake of the annealed membranes. The flux of water and bromide solutes through the 135 pm thick crosslinked and annealed NYgAM membranes at 332% graft yield was found to be approximately equal to that of 18 pm thick cellophane films. The permeability coefficients of urea, uric acid, r&ase, and inulin through the crosslinked annealed NYgAM membranes were determined in order to establish the potential applicability of the modified membranes to clinical separation of metabolites. The flux of all four solutes, especially that of uric acid, through the modified NYgAM merLbranes at 100% graft yield was found to be higher than through the cellophane films. In addition, the flux of inulin was found to be strongly affected by variation in graft yields.