新型高分子螯合-絮凝剂制备条件的响应面法优化

以壳聚糖为原料,采用化学合成法将二硫代羧基引入到其高分子链上,制备出一种新型高分子螯合-絮凝剂二硫代羧基化壳聚糖(R′-N-(C=S)-SNa,简称DTCTS).以水样中Cd(Ⅱ)的去除率为考察对象,在单因素实验法的基础上,选取了制备DTCTS的主要影响因素,并采用中心复合设计实验和响应面分析法对DTCTS制备条件进行了优化.结果表明,建立的二次多项式模型回归性显著而失拟项不显著,决定系数R2为0.9829,模型拟合性良好;DTCTS最佳制备条件为:反应物CTS/CS2/NaOH摩尔比1:1.5:2、预反应时间30min、主反应温度60℃,此条件下制备的DTCTS对Cd(Ⅱ)的去除率可达99.52%,与模型预测值相对偏差为0.05%,模型可靠.

Optimization of preparation conditions of novel macromolecule chelating-flocculant by response surface methodology.

A novel macromolecule chelating-flocculant dithiocarboxyl chitosan (DTCTS) was synthesized by grafting a dithiocarboxylic group onto chitosan. Taking removal rate of Cd (Ⅱ) in water samples as the main indicator, the optimal conditions for preparing DTCTS were investigated with central composite design and response surface methodology (RSM) based on single-factor experiments. A quadratic polynomial regression model was established to predict the removal efficiency. The results showed that the regression of this model was significant while the lack of fit was not significant. The determination coefficient (R2) was 0.9829, which demonstrated the model had good agreements with experimental data. Determined by optimized response surface, the optimum conditions for the preparation of DTCTS were as follows: the molar ratio of CTS/CS2/NaOH was 1:1.5:2, pre-reaction time was 30min, and main-reaction temperature was 60℃. Under the optimum conditions, the removal rate of Cd(Ⅱ) could be reached 99.52%. The relative deviation between experimental and predicted value was only 0.05%, which proved the model was reasonable and feasible.