Studies on Ternary Heteropoly Acids in Analytical Chemistry

点击翻译按钮获取中文摘要

An inorganic heteropoly anion produced through the reaction of an isopoly molybdate anion with a phosphate one was found to have very specific character acting as an analytical reagent for heavy elements and alkali elements. Each of group 4A elements such as Ti( <IV> ), Zr( <IV> ), Hf( <IV> ), Th( <IV> ) and Ce( <IV> ) and group 5A elements such as V( <V> ), Nb( <V> ) and Ta( <V> ), in the periodic table, could be substituted for one of the molybdenum elements so as to form a ternary heteropoly anion. The nuclear magnetic resonance spectrum of each ternary heteropoly anion shows a specific chemical shift for each substituted heavy element in its resonance peak position. This fact is quite useful for simultaneous quantitative analysis of the group 4A and group 5A elements in the aqueous medium.The solute-solvent interaction was investigated to find out the empirical parameters for the extraction of each ternary heteropoly anion in organic solvents. These parameters were applied to the selective separation of 12-molybdosilicate and 12-molybdophosphate and also to that of the binary heteropoly anion and the ternary one.The local structure around the molybdenum atom in the binary heteropoly anion and the ternary one and that around the vanadium atom in the 11-molybdo-vanado-phosphate vanado-phosphate ternary heteropoly anion were examined by extended X-ray absorption fine structure analysis.