Design of high efficiency polymeric cation exchange fibers

In this study we have been exploring a new ion exchange material in the for m of a fiber that could yield a number of important advantages over convent ional ion exchange beads. In this approach, ion exchange fibers are prepare d by 1) coating low-cost glass fiber substrates with a polystyrene/divinylb enzene oligomer, 2) curing, and 3) sulfonating. The sulfonation process and effects of varying degrees of crosslinking were characterized through diff use reflectance infrared spectroscopy and acid-base neutralization titratio ns. Capacities of 4.7 meq/g (on a per resin basis) were easily obtained. Ki netics experiments showed the contact efficiencies of the new systems were greatly improved over the traditional beads due to greater surface associat ed with the pm morphology and shorter diffusion lengths. This translated in to an order of magnitude increase in ion exchange rate. As a result of the thin coatings, the use of solvents prior to functionalization, and preswell ing of the finished product prior to end-use were eliminated. Scanning elec tron microscopy was used to image the fibers and track their mechanical int egrity through various stages of the process. Finally, repetitive regenerat ions proved the long-term stability of the spent fibers. Copyright (C) 2001 John Wiley & Sons, Ltd.