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从三磷酸钠的碱性溶液中,用臭氧氧化镨(Ⅲ)获得了四价镨的棕黄色溶液。研究了Ag~+及Ce~(3+)对镨氧化率的影响,观察到Ag~+对镨的氧化无催化作用,而Ce~(3+)却有明显的“带同氧化作用”。氧化前后溶液、氧化后放置的溶液和加还原剂后溶液的吸收光谱证实位于332nm 附近的吸收峰与Pr(Ⅳ)的存在有关。利用分光光度法测定了四价镨溶液的还原动力学,指出Pr(Ⅳ)的还原反应为一级反映;求得了不同pH时的速率常数和半还原期。
From the alkaline solution of sodium tripolyphosphate, praseodymium (Ⅲ) was obtained as a brownish yellow solution of tetravalent praseodymium. The effect of Ag ~ + and Ce ~ (3+) on the oxidation rate of praseodymium was studied. It was observed that there was no catalytic effect of Ag ~ + on the oxidation of praseodymium, while the obvious “banding” effect was observed on Ce ~ (3+). The absorption spectra of the solution before and after oxidation, the solution after oxidation and the solution after the addition of a reducing agent confirmed that the absorption peak at around 332 nm is related to the presence of Pr (IV). The reduction kinetics of tetravalent praseodymium solution was determined by spectrophotometry. The reduction reaction of Pr (Ⅳ) was first order reaction, and the rate constant and half-reduction period at different pH were obtained.