摘要
采用pH电位滴定方法,运用先进的配位常数计算程序,通过恰当配位化学模型(H4L)的建立,研究了水溶液中环境友好聚合物聚天冬氨酸(PASP)自身的解离平衡及其与Ca2+、Mg2+离子间的配位化学作用,测定了相应的各级酸解离常数和配合物稳定常数,所得配位常数及稳定常数结果合理,计算及实验结果可以很好地吻合,并得到了各配合物物种在不同pH值条件下的分布。得到PASP的各级解离常数pKai分别为2.27、3.66、4.22和5.40,误差为0.006 1;PASP对溶液中Ca2+、Mg2+离子具有良好的配位能力,形成的配合物稳定常数lgβ值在2.97~13.15之间。
By means of pH potentiometric titration, the dissociation equilibrium of polyaspartic acid （PASP） and its complexation with two divalent cations（ Ca^2＋ , Mg^2＋ ） were studied. Considering the complexity of the dissociation of polyaspartic acid in aqueous solution, a proper model of PASP （H4 L） was constructed to simulate the dissociation process of PASP. The computer program BEST developed by A. E Martell was used to determine the dissociation constants of PASP and the stability constants of the related PASP complexes with Ca^2＋ or Mg^2＋. According species in aqueous solution 2.27, 3.66, 4.22, andS. with Ca^2＋ or Mg^2＋ ranged to the experimental and computation results, the distributions of PASP complex at different pH values were given out. The dissociation constants pKai of PASP were 40 respectively with an erroe of 0. 006 1. The stability constants（lgβ） of PASP from 2.97 to 13.15. The results show that PASP is a good ligand for forming different complexes with Ca^2＋ or Mg^2＋ under a wider range pH .
出处
《应用化学》
CAS
CSCD
北大核心
2006年第4期366-369,共4页
Chinese Journal of Applied Chemistry
基金
国家自然科学基金(50478103)
科技部-小城镇科技发展重大项目(2003BA808A17)资助课题
关键词
pH电位滴定
聚天冬氨酸
配位化学
钙离子
镁离子
pH potentiometric titration,polyaspartic acid（ PASP）, coordination chemistry, calcium sium ion
