A Novel Method for Obtaining a High-Concentration Chitosan Solution and Preparing a High-Strength Chitosan Hollow-Fiber Membrane with an Excellent Adsorption Capacity

The biopolymer chitosan (CS) has been widely studied for various environmental and biomedical applications. However, the production of homogeneous CS solutions with high concentrations and the preparation of CS hollow-fiber membranes with high mechanical strengths for practical applications have been a great challenge so far. In this study, a novel dilute-dissolution and evaporating-concentration method was developed to allow highly concentrated homogeneous CS solutions to be easily prepared (up to 18 wt % as compared to <= 5 wt % prepared by the conventional method). CS hollow-fiber membranes prepared from high-concentration CS solutions showed greatly improved mechanical strengths (with tensile strengths up to 3.4 MPa), comparable to or even better than other hollow fibers made from many conventional industrial synthetic polymers. The prepared hollow-fiber membranes were found to possess very high adsorption capacities for heavy-metal ions (up to 206.6 mg of Cu2+/g of CS fiber at pH 5), which were attributed to the low crystallinity of CS and the porous structure achieved in the hollow-fiber membranes. As a potential application example, the performance of the prepared hollow fibers for the adsorption of copper ions in real wastewater from a wafer fabrication factory in Singapore was also examined. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 115: 1913-1921, 2010