Studies On Chemical Modifications Of Chitosan Under Microwave Radiation And Applications Of Their Products

Chitin is a natural polymer extracted from Crustacea Shell, such as Praws, Crabs, Insects and Shrimps, with very abundant of sources in nature. Chitosan, a poly(D-glucosamine), is prepared from chitin by deacetylating its acetoamide groups with a strong alkali solution. Chitosan has already been described as a suitable natural polymer for collection of metal ions through chelating, due to the presence of an amino group of the 2-amino-2-deoxy -D-glucose(glucosoamine) unit, in which the amino group of the 2-amino-2-deoxy -D-glucose (glucosamine) unit plays an important role. The amino group is also responsible for dissolution of chitosan in acidic media. This is one serious disadvantage from the practical viewpoint; thus, chitosan must be made into resins with dissolution in acidic media through chemical modification.The enhancement reactions of microwave radiation and its characteristics have received considerable attentions from a number of researchers in fields of Microwave and Chemistry. Through recent developments, Microwavechemistry, a new kind of crossing dicipline has been founded. Microwave radiation was firstly used to chemical modifications of chitosan by us, and the adsorption properties of chemically modified chitosan resins were investigated. Thereby, the effects of microwave radiation on some reactions have been discussedAt first, in the sealed reactor made from Teflon container and under condition of microwave radiation, direct cross-linking reaction with aldehyde, and the adsorption properties of the resins obtained by cross-linking reaction with aldehyde were investigated, as compared with that of resins prepared by using water-bath heating. The results show that obtained resins can be reused with dissolution in acidic media; and the equilibrium adsorption capacities of obtained resins under microwave radiation are bigger than that of obtained resins by water-bath heating at the same crossing percent. To reach the same crossing percent, it took 3 minutes for microwave radiation, and 2 hours for water-bath heating, and rate enhancements up...