壳聚糖离解平衡常数的测定

Determination of the dissociation constants of chitosan

用电位滴定法研究了水溶液中壳聚糖的离解平衡常数 ,可用Katchalsky’s方程描述 ,壳聚糖的pKa 与溶液中离子强度及种类有关 ,其值分别为 :6 170、6 382 (0 1mol/LNaCl)、6 390 (0 1mol/LKCl)、6 5 92 (0 5mol/LNaCl)、6 72 5 (0 5mol/LKCl)。壳聚糖pKa 值及变化规律解释了壳聚糖与金属离子配位和回收有毒金属离子过程中的盐效应机理 。

The dissociation constants of chitosan in aqueous solutions were investigated by potentiometric titration. It is shown that the potentionmetric behavior is well described by the Katchalsky's equation, and the p K a varys with the ionic strength and is dependent on the added salts, and its corresponding value is 6 170,6 382(0 1 mol/L NaCl),and 6 390(0 1 mol/L KCl),6 592(0 5 mol/L NaCl),and 6 725(0 5 mol/L KCl)respectively. The varing rule of p K a explained the coordination of chitoson with metal ions and interpreted the mechanism of salt effect in the removal of heavy metal ions. Some basic parameters of chitosan were provided.