壳聚糖-Cu(Ⅱ)吸附条件的优化

Adsorption Conditions Optimization of Cu(Ⅱ) to Chitosan

利用多因素正交试验L16(45)研究反应物的比例、反应pH值、反应温度以及反应时间,对壳聚糖-Cu(Ⅱ)吸附作用的影响。通过定氮法测定反应产物中壳聚糖的含量,等离子发射光谱法(ICP-AES)测定样品的铜含量。结果显示:在试验范围内,壳聚糖对Cu(Ⅱ)的吸附作用,随着Cu(Ⅱ)与壳聚糖结构单元的摩尔比、体系pH值、反应温度及反应时间的增加而增强。各个因素对Cu(Ⅱ)吸附量的影响从大到小为:体系的pH值>壳聚糖结构单元与Cu(Ⅱ)的摩尔比>>反应温度>反应时间。最佳吸附条件是:壳聚糖的结构单元与铜的摩尔比1∶1,pH4·5,温度40℃,反应时间10h,但吸附作用在前4h较强。在最佳反应条件下,壳聚糖的氨基结构单元可与Cu(Ⅱ)以1·5∶1(摩尔比)的形式存在于产物中。紫外可见及红外光谱分析表明Cu(Ⅱ)与壳聚糖分子中的氨基及羟基都发生了配位作用。

Adsorption conditions of Cu （ II ） to chitosan were optimized using multi - factor orthogonal experiment L16 （4^5 ）. Chitosan and Cu （ II ） contents of the resultant product were calculated or determined by testing the nitrogen content of the sample and Inductively Coupled Plasma Emission Spectrum （ICP - AES） respectively. The results indicate that Cu （ II ） content of the resultant product increases with the increase of the mol ratio of Cu （ II ） to structural unit of chitosan, pH value, reaction temperature and reaction time. Main factors affecting the adsorption conditions could be arranged in a decreasing order according to their abilities of the effect on the adsorption amount of Cu （ II ） ： pH of the reaction system 〉 mol ratio of Cu （ II ） to structure unit of chitosan 〉〉 reaction temperature〉 reaction time. The optimal reaction conditions are ： pH 4.5, mol ratio of structure unit of copper ions to chitosan 1 ： 1, reaction temperature 40℃, and reaction time 10 h, but the absorption carries out quickly in the first 4 h. Chitosan and Cu （ II ） might form a complex with the highest chelating ratio of 1.5：1 under optimal reaction conditions. Uhro - violet visible （UV） and Fourier transform infrared spectra （FTIR） of initial chitosan and adsorption product indicate that amino group as well as both primary and secondary hydroxyl groups at C - 2, C - 3 and C - 6 positions of chitosan are chelated with Cu （II）.