2014 : Degradation of chitosan by sonication in very-low-concentration acetic acid

Prof. Dr. Ir. Achmad Roesyadi M.Sc
Dr. Ir. Sumarno M.Eng.
Dr. Ir. Sri Rachmania Juliastuti M.Eng


Abstract

Chitosan is a linear copolymer composed of (1 → 4)–linked 2-acetamido-2-deoxy-β-D-glucan (GlcNAc) and 2-amino-2-deoxy-β-D-glucan (GlcN) units in varying proportions, having a high molecular weight and strong intra- and intermolecular hydrogen bondings. Sonication has become an alternative for degrading chitosan into low-molecular-weight chitosan (LMWC), chitosan oligomers and glucosamine. In this study, chitosan was treated with sonication at 40 °C and 60 °C for 30 min and 120 min with various acetic acid concentrations (0.2% v/v–1% v/v); the very-low-concentration acid solution functioned both as a solvent and catalyst. After sonication, the samples were tested for changes in molecular weight, water soluble proportion of chitosan (chitosan oligomers and glucosamine), degree of deacetylation, degree of crystallinity, and morphology. The soluble and insoluble product yields at low concentration (0.5 …