Chitosan-based adsorbents & nanocomposite membranes for separation applications

• Main Author: Xu, Dan
• Other Authors: Wang Kean
• Format: Theses and Dissertations
• Language: English
• Published: 2011
• Subjects: DRNTU::Engineering::Materials::Biomaterials; DRNTU::Engineering::Chemical engineering::Biotechnological production
• Online Access: https://hdl.handle.net/10356/42894
• Institution: Nanyang Technological University

Chitosan (CS) is an important biomaterial widely used in purification and separation applications. This project has developed two novel CS-based materials for industrial applications, i.e. (1) CS hydrogel beads for wastewater treatment, and (2) CS nanocomposite membranes for pervaporation separations. In application (1), native CS beads were modified with ammonium sulfate to remove anionic dyes in aqueous solutions at a high pH of 8.2, which was designated for direct treatment of wastewater discharged from textile plants. The adsorption capacities of the modified CS beads towards acid orange-7 (AO-7) and acid red-18 (AR-18) in a fixed bed were 445.6 mg/g and 427.2 mg/g, respectively, which were about 7.4 and 14.4 times of those of the native CS beads at pH 8.2 (60.4 mg/g for AO-7 and 29.7 mg/g for AR-18), respectively. The ion-exchange mechanism of dye adsorption on the modified beads was proposed and verified experimentally. The modified beads were found to be easy to regenerate (with common chemicals) and possessed excellent re-use capability (up to 20 cycles without significant loss in capacity). The fixed bed breakthrough kinetics of AO-7 was measured on the modified beads and was modeled successfully by the Wheeler-Jonas equation with a ‘two-segmented’ approach.