The Anion Exchange Chromatographic Studies on the Polymerization Equilibria of Molybdate and Tungstate and the Production of APT

[摘要] The elution behaviour of molybdate and tungstate through anion exchange column has been studied at the various pH. A discussion is made to evaluate the equilibrium constants of the polymerization of these acids comparing with the behaviour of chromate ion and dichromate ion. The eqailibrium constants found at 20¡É are K = 4¡¿1053 for 7MoO42- + 8H+ ¡ê Mo7O246- + 4H2O K = 3¡¿1054 for 6WO42- + 7H+ ¡ê HW6O215- + 7H2O referring to this results the conditions of separation of tungstate and molybdate are obtained. iThe quantitative separations of carbonate, molybdate and tungstate from the pregnant solution have been established by anion exchange chromatography, using the 22 cm¡¿44.27 cm2 column of Rexyn 201. The optimum eluents for the quantitative separation of those ions are as follows; 0.2M solution of sodium chloride at pH 8 for carbonate, the mixture of 0.5 M ammonium chloride and 0.05 M sodium sulfate at pH 5 for molybdate and 0.5 M solution of ammonium chloride at pH 10 for tungstate. Tungstate is directly recovered from the pregnant solution as a form of ammonium paratungstate, by eluting with ammonium chloride solution.

[学科分类] 化学（综合）