Alkali induced changes in spatial distribution of functional groups in carboxymethylated cellulose – comparison of cotton and viscose fibers

Abstract

AbstractThe aim of the work was to compare the levels of carboxymethylation on cotton with what was obtained previously on viscose fibers under the same treatment conditions. In addition to carboxymethylation levels, their performance was also compared in terms of their propensity for sorption of methylene blue, a cationic dye that is a putative wastewater contaminant. Under comparable conditions of treatment, the degree of carboxymethylation in cotton was 30–90% of that in viscose but the molar ratio of dye sorption to carboxyl groups was 100–230% of that in viscose. In other words, as compared to cotton, viscose fibers showed higher degrees of carboxymethylation but lower accessibility of the carboxyl groups to dye molecules. The divergence between the fiber types is attributed to differences in the spatial distribution of substituted carboxymethyl groups within their structures, as well as the inherently greater swelling propensity of the viscose as compared to cotton. Further work is under way to determine if the order of performance as measured through dye sorption (cotton better than viscose) will also hold true if the performance metric is changed to water and moisture sorption.