Fouling of anion exchanger by image and FTIR analyses
Paweł Wiercik, Barbara Frączek, Przemysław Chrobot
Abstract
Organic fouling of an anion exchange resin results from the adsorption of the organics on its surface which block the diffusion of mobile ions inside the resin beads. As a result a decrease in a total capacity is observed. Generally the performance of anion exchangers is determined based on the breakthrough curves and studies of the adsorption kinetics. To the authors’ knowledge, the application of Fourier-transform infrared (FTIR) spectroscopy and image analysis to examine the surface changes of anion exchangers is a novel approach to this issue. The image analysis provides information about the size and the shape of the particles based on the morphological parameters and FTIR spectroscopy enables identification of the foulants. In this paper, image and FTIR analyses were applied to assess the effect of organic compounds on changes of the size and shape of a strongly basic anion exchanger in the process of treating of partially nitrificated digester reject water. The digester reject water resulted from dewatering of sludge and subjected to partial nitrification was subsequently fed through the anion exchange resin. FTIR analyses enabled identification of the foulant as humic substances, which accumulated on the beads surface and remained after regeneration. The image analyses helped to observe the changes of beads shapes from smooth and circular to uneven and oval.