A kinetic study of nickel complexation in model systems by adsorptive cathodic stripping voltammetry.
A kinetic study of nickel complexation in model systems by adsorptive cathodic stripping voltammetry.
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通过吸附阴极溶出伏安法研究模型系统中镍络合的动力学。
DOI：
10.1021/es001203q
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发表时间：
2001
影响因子：
11.4
通讯作者：
C. L. Chakrabarti
中科院分区：
文献类型：
--
作者：
V. Celo;J. Murimboh;M. Salam;C. L. Chakrabarti
研究了吸附阴极溶出伏安法（AdCSV）结合竞争配体交换法（CLEM）作为测量模型体系中镍配合物解离速率系数的工具。二甲基乙肟（DMG）作为竞争配体。以柠檬酸（CA）和表征良好的黄腐酸（FA）为模型配体。计算了速率系数，并讨论了平衡和动力学数据的一致性。研究了析取途径（通过初始配合物的解离进行）和辅助途径（通过竞争配体直接攻击初始配合物而形成中间配合物）对整个反应的贡献。Ni-CA或Ni-FA配合物与DMG的反应可以通过分离和辅助途径进行。整个反应的主要途径取决于镍与初始配体的比例和dmg与初始配体的比例。当[DMG] >或= 3 mM和Ni /溶解有机碳（DOC）比大于10 nM Ni 2+/g DOC时，反应主要遵循析取途径。由于淡水中游离镍离子有毒性，其形成的速率和途径引起了人们的关注。
Adsorptive cathodic stripping voltammetry (AdCSV) in conjunction with the competing ligand-exchange method (CLEM) was investigated as a tool for measuring dissociation rate coefficients of nickel complexes in model systems. Dimethylglyoxime (DMG) was used as the competing ligand. Citric acid (CA) and a well-characterized fulvic acid (FA) were used as model ligands. The rate coefficients were calculated, and the consistency of equilibrium and kinetic data was discussed. The contributions of the disjunctive pathway (proceeding by the dissociation of the initial complex) and the adjunctive pathway (proceeding by the formation of an intermediate complex as a result of direct attack of the competing ligand on the initial complex) on the overall reactions were investigated. The reactions of Ni-CA or Ni-FA complexes with DMG were demonstrated to proceed by both disjunctive and adjunctive pathways. The predominant pathway for the overall reaction depends on the nickel-to-initial ligand and the DMG-to-initial ligand ratios. The reactions follow predominantly the disjunctive pathway for [DMG] > or = 3 mM and Ni-to-dissolved organic carbon (DOC) ratios greater than 10 nM Ni 2+/g of DOC. Since free nickel ion in freshwaters is reported to be toxic, its rate and pathway of formation are of environmental concern.