Dye adsorption and desorption characteristics of CM-chitin/chitin whisker bionanocomposite films

Abstract

Carboxymethyl chitin (CM-chitin)/chitin whisker (CTW) bio nanocomposite films were fabricated by solution casting technique. Glyoxal was used as a crosslinking agent for retaining shape of the films in wet state. The effects of crosslinking concentrations on physical properties of the films were evaluated in terms of swelling behaviour and weight loss. Methylene blue, a cationic dye and methyl orange, an anionic dye, were selected as model compounds in order to examine the adsorption and desorption characteristics of the films. The effects of solvent of dye, blend composition and types of dye on the dye adsorption of the films were investigated as a function of adsorption time. The CM-chitin film crosslinking with glyoxal could form hydrogel in wet state and had high degree of swelling with low percentage of weight loss. The presence of CTW in the crosslinked CM-chitin films resulted in the improvement in shape stability. Furthermore, CM-chitin films had higher adsorption capacities for the methylene blue than methyl orange because of the interaction between carboxymethyl group and cationic group of the dye. The existence of chitin whisker in composite films exhibited the lower adsorption and desorption due to the low degree of swelling.