首页> 外文期刊>Analytica chimica acta >PSEUDOPOLAROGRAPHIC DETERMINATION OF STABILITY CONSTANTS OF LABILE ZINC COMPLEXES IN FRESH WATER
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PSEUDOPOLAROGRAPHIC DETERMINATION OF STABILITY CONSTANTS OF LABILE ZINC COMPLEXES IN FRESH WATER

机译:伪柱法测定淡水中锌络合物的稳定常数。

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The formation and distribution of labile zinc species in fresh water were investigated by using a pseudopolarographic approach. Pseudopolarograms were obtained by plotting the anodic stripping voltammetric peak current versus the deposition potential for a series of solutions containing 100 mu g/l Zn(II) and increasing amounts of Iigand, at the pH of a typical river water sample. Stoichiometry and stability constants of the complexes were evaluated from the shift of the half-wave potential of the pseudopolarogram as a function of the ligand concentration. Four major inorganic ligands occurring in river waters were examined: chloride, hydrogenphosphate, hydrogencarbonate and sulphate, but no shift was obtained for chloride at the concentration levels tested. The species ZnHPO4, Zn(HPO4)(3)(4-) ZnHCO3+, Zn(HCO3)(2) and ZnSO4 were found to occur at ligand concentrations less than or equal to 0.25 M, and their stability constants calculated. The distribution diagram of Zn in the river water investigated showed that Zn species present in concentration 2 0.1% of the total amount of metal were: Zn(H2O)(2) (aquo-ion), ZnHPO4, ZnHCO3+, Zn(HCO3)(2), ZnSO4, ZnOH+ and Zn(OH)(2). Species of higher coordination index only appear at a ligand concentration superior to that present in fresh water. [References: 27]
机译:使用伪极谱法研究了淡水中不稳定锌物质的形成和分布。通过在典型河水样品的pH值下绘制一系列阳极溶出伏安法峰值电流与一系列含100μg / l Zn(II)和增加量的Iigand的溶液的沉积电位相对应的伪极谱图。从假极谱图的半波电位随配体浓度的变化评估配合物的化学计量和稳定性常数。考察了河水中出现的四种主要无机配体:氯离子,磷酸氢根,碳酸氢根和硫酸根,但在所测试的浓度水平下,氯离子没有变化。发现ZnHPO4,Zn(HPO4)(3)(4-)ZnHCO3 +,Zn(HCO3)(2)和ZnSO4的存在浓度小于或等于0.25 M,并计算了其稳定常数。锌在河水中的分布图表明,浓度2占金属总量0.1%的锌种类为:Zn(H2O)(2)(aquo-ion),ZnHPO4,ZnHCO3 +,Zn(HCO3)( 2),ZnSO4,ZnOH +和Zn(OH)(2)。配位指数较高的物种仅在配体浓度高于淡水中的配体浓度下出现。 [参考:27]

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