Study On The Synthesis And Adsorption Behaviour Of Chitosan Derivative

China is a big country of aquatic products, with abundant marine resources, including shrimp crab shells resources which are the main raw material for industrial production of chitin and chitosan. Chitosan is an N-deacetylated product of chitin and its chemical name is (1-4)-2-acetamido-2-deoxy-β-D -glucose. Chitosan possesses widely application such as medicine, food, paper, chemical, and enzyme immobilization carriers fields and so on due to its non-toxic, biocompatibility and biodegradability. However, chitosan has a dense crystal structure which limiting its activity and applications. The modification of chitosan is armed to increase its application performance. Therefore, chemical modification of chitosan was studied to gain new chitosan derivative. Then its application for the treatment of heavy metal and aniline and nitrite nitrogen by adsorption was studied for exploiting new chitosan derivative used for water treatment agent provides the foundation research data. The main research contents and results are as follows:1. Synthesis of chitosan derivativeBy orthogonal experimental design, the influence of factors, such as amount of chitosan, the initial concentration of Fe²⁺, pH were studied. Results showed that the best conditions of the reaction were: for 50 mL reaction system, the amount of chitosan was 0.1 g with initial concentration of Fe²⁺ 16 mg/mL, pH=2. CTS coordination of Fe²⁺ could reach 413.54 mg/g.HPCS-Fe(Ⅱ) was synthesized in constant temperature water bath and the influence of factors such as reaction temperature, time, concentration of dispersants and catalyst were investigated. The experimental results of the optimumation for preparation of HPCS-Fe(Ⅱ) were as follows: the ratio of volumn of epoxypropane and isopropyl alcohol and catalyst and the ratio of gram of chitosan-Fe(Ⅱ) was 10 ml:8 ml:10 ml:1 g, at the etherify temperature 60℃, etherify time 6 h. The substitution degree of the production was 0.61.2. Characterization of chitosan derivativeTwo Main performance figures of the raw material chitosan were measured. The degree of deacetylation was 91.3% and the viscosity average molecular weight was M_w=1.189×10³. By UV absorption it indicated that -NH2 was the main adsorption site of Fe(Ⅱ) on chitosan. Through reaction with dissooform, it showed that there existed structure of [-CH2CH(OH)CH3-] in HPCS-Fe(Ⅱ). After dissolution experiments, the product had good water solubility.3. Adsorption characteristics of aniline and nitrite nitrogen on HPCS-Fe(Ⅱ)The adsorption characteristics of aniline and nitrite nitrogen on HPCS-Fe(Ⅱ) were studied by comparing tests at different conditions. The results showed that the adsorbility capacities and adsorption rate of HPCS-Fe(Ⅱ) was higher than chitosan by the adsorption tests of aniline and nitrite nitrogen with HPCS-FE and CTS. The adsorbance on HPCS-Fe(Ⅱ) to aniline came to the maximum when pH was 4, adsorption time for 150min, dose of adsorbent 0.05 g with adsorbility capacities of 5.401 mg/g and adsorption rate of 26.019%. The adsorbance on HPCS-Fe(Ⅱ) to nitrite nitrogen came to the maximum when pH was 5, adsorption time for 90min and dose of adsorbent was 0.05 g with adsorbility capacities of 0.139 mg/g and adsorption rate of 19.892%.4. Adsorption kinetics of heavy metals on HPCS-Fe(Ⅱ)Through moving adsorption process, adsorption kinetics and adsorption isotherms of Cu²⁺, Pb²⁺, Cd²⁺ on HPCS-Fe(Ⅱ) was studied. The adsorption reaction could not be described by the first order reaction, but could be well described using second order rate model. The adsorption isotherms of HPCS-Fe(Ⅱ) to Cu²⁺ and Pb²⁺ corresponded well with Langmuir equation. However, its not suitable for HPCS-Fe(Ⅱ) to Cd²⁺.