Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/13306
Title: Study of Chitosan-based biopolymer adsorbents and their applications in heavy metal removal
Authors: LI NAN
Keywords: chitosan, biopolymers, adsorbents, heavy metal, modification, application
Issue Date: 7-Aug-2007
Source: LI NAN (2007-08-07). Study of Chitosan-based biopolymer adsorbents and their applications in heavy metal removal. ScholarBank@NUS Repository.
Abstract: Biopolymers have attracted great research interest in their use as effective adsorbents in recent years. Chitosan, a natural biopolymer, has been found to be capable of chemically or physically adsorbing various heavy metal ions. In this study, chitosan-based biopolymer adsorbents were prepared for improved material properties and enhanced performance in the removal of heavy metal ions. The research included synthesis and characterizations of mechanically strong chitosan-cellulose hydrogel beads through polymer blending, improvement of chitosan hydrogel beads for acid resistance through a novel amine-protected crosslinking method, functionalization of chitosan beads with polyacrylamide through surface initiated grafting for selective adsorption of heavy metal ions, and modification of chitosan beads with polyacrylic acid through surface grafting for enhanced adsorption performance of heavy metal ions. It was found that the addition of cellulose into chitosan made the hydrogel beads materially denser and mechanically stronger, crosslinking extended the chemical stability of the chitosan-cellulose beads in solutions with pH values from 4 down to 1. Amine-shielded crosslinking method significantly improved the metal adsorption capacity of the crosslinked chitosan beads. Chitosan-g-polyacrylamide beads showed excellent selectivity for the adsorption of mercury ion over lead ions. Chitosan-g-poly(acrylic acid) beads displayed greatly enhanced adsorption capacity for lead ions. The mechanisms involved in material modification and metal ion adsorption were also examined.
URI: http://scholarbank.nus.edu.sg/handle/10635/13306
Appears in Collections:Ph.D Theses (Open)

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