中文摘要：

N，O-羧甲基化度为85．6％的羧甲：基壳聚糖（CM-CTS）为原料，w=0．40的NaOH水溶液为催化剂，3-氯-2-羟丙基三甲氯化铵（CTA）为接枝改性剂，在异丙醇介质中刳备了具有良好水溶性的两性壳聚糖-季铵化N，O-羧甲基壳聚糖；分别以产物对模拟废水中的Cd＋和Cr（Ⅵ）的絮凝去除奉为基准对两性壳聚糖的合成条件进行了优化，用IR和1H NMR对产物的结构进行了表征。研究结果表明产物Cr（Ⅵ）的去除率更适宜作为合成紊件的优化基准，且对应的优化条件为：季铵化反应时间为10．0h，反应温度为60．0℃，mNaOH／mCM-CTS=0．50，mCTAS/mCM-CTS=1．5，在此条件下合成产物对Cr（Ⅵ）的最大絮凝去除率为93．16％，对Cd2＋的最大絮凝去除率98．52％。

英文摘要：

A amphoteric chitosan with a higher solubility in water was prepared with 2-propanol as solvent, w= 0. 40 NaOH aqueous solution as catalyst, 3-chloro-2-hydroxypropyl trimethlyammonium chloride （CTA） as grafting agent and N,O-carboxymethylchitosan（CM-CTS） with carhoxymethyl degree of 85.6 as starting material. The synthetic conditions were optimized according to orthogonal experimens that based on the removal rate of Cd2＋ and Cr（Ⅵ）, respectively. The product was characterized by iR and 1H NMR. The experimental resuls showed the removal rate of Cr（Ⅵ ） could more suitably be regarded as the basis for the optimization of synthetic conditions. The optimized conditions were as follows the reaction time was 10. 0 h, the temperature was 60. 0℃ ,mNaOH/mCM-CTS=0.50,mCTAS/mCM-CTS=1.5. The maximum removal ratio of Cr（ VI ）and Cd2＋ for the product prepared under these conditions could reach up to 93.16% and 98.52;, resrpectively.