Research On Preparation And Adsorption Characteristic Of Aminated Chitosan

Chitin and its derivative as well as Chitosan have many useful features, for example, hydrophilicity, biocompatibility, biodegradability, antibacterial property, and remarkable affinity for many proteins. As it is harmless to humans and abundantly available, ion exchangers or adsorbents made from chitosan may also have potential as separators in life sciences, medical and agricultural drugs, environment engineering and other industrial applications. In recent twenty years, scientists in many countries have all attached importance to the research on chitosan and its derivatives. As an adsorbent of heavy metal ions, chitosan has strong chelating ability and can be used to dispose heavy metal ions in industrial waste water or reclaim costly metal. It can't engender pollution again and the resources are reclaimed too. So the research on chitosan has important significance both in entironment protection and the development of country economy. Based on the investigations of literatures, we find that when we use chitosan as an adsorbent in an industrial scale column, flake and gel chitosan do not give a high efficiency and are soluble in acid solutions. Its adsorption capability is not high enough. All of these restrict the applications of chitosan. Therefore, preparation and adsorptive characteristic of porous aminated - chitosan resin have been studied in this paper. The research work could be divided into the following two parts.1. Preparation and adsorptive characteristic of porous polyethyleneimine -chitosan resinWe prepared porous chitosan microsphere by spraying solution of chitosan in acetic acid and ethanol into a diluted NaOH aqueous solution through a thin burette. We discussed the effect of concentration of solution of chitosan in acetic acid and ethanol, NaOH aqueous solution and ethanol on the shape and structure of the pores. After experiences, we find the appropriate preparation condition is: 3-4 %(m/V)chitosan solution, 20%(V/V) ethanol and 10%(m/V) NaOH=In order to make the chitosan microspheres insert to acid and have preferable adsorption capability, we cross-linked them with epichlorohydrin. Then a novel porous chitosan (PEI-CTS), which has higher concentration of amino group, was synthesized by polyamination with poly(ethylene imine) on cross-linking chitosan. The preparation conditions are discussed. The size distribution of porous chitosan spherical particles is symmetrical, it is about 300~400um and the pore diameter is 3.5nm. The specitic surface area is 1.03m~2·g~-1. The SEM photo shows the micropore is not penetrable.The adsorption capacity of PEI-CTS for Cu~2+and Ni~2+ was also investigated. It is best described by the second-order kinetic equation. The equilibrium isotherms for the adsorption of Cu ~+ and Ni ~+ were correlated by the Langmuir equation and Freundlich equation respectively. The results show that the spherical resins have maximum adsorption capacity for the ions at pH=5.0 and the saturation capacity of the resin has no obvious change after regeneration times.2. Preparation and adsorptive characteristic of porous diethylenetriamine -chitosan resinA novel porous chitosan (DETA-CTS), which has higher concentration of amino group, was synthesized by animation with diethylenetriamine on cross-linking chitosan. The best preparation condition is 50%(V/V)diethylenetriamine, 60℃, 7h. The size distribution of porous chitosan spherical particles is about 50~100μm and the pore diameter is 2.0~3.0nm. The specitic surface area is 1.30m~2·g~-1 and the resin has preferable durability in the acid solution.The adsorption capacity of DETA-CTS for Cu~2+, Ni~2+ and Pb~2+ was also investigated. The saturated adsorption capacity of DETA-CTS for Cu~2+ and Ni~2+ increased 45% and 88% respectly than the saturated adsorption capacity of PEI-CTS and the time used to achieve adsorption balance is also about 10h which less than PEI-CTS. The adsorption behavior is best described by the second-order kinetic equation. The equilibrium isotherms for the adsorption of Cu~2+, Ni~2+ and Pb~2+ were...