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银对锰—过硫酸盐反应的催化作用是熟知的.本文经试验查明,在一定条件下,其反应速度(体现为反应生成的MnO_4~-浓度)与银离子浓度成正比,利用此反应成功地测定了高纯铝中超微量银.当确定锰离子浓度为6×10~(-4)M、过硫酸钾浓度为1.85M、保持磷酸酸度为1.44M、总体积为10毫升并在沸水浴中加热7分钟,则反应速度与限定的银离子浓度成正比,当C_(Ag)为0～4×10~(-7)M保持直线关系.铝中银的分离富集采用双硫腙萃取法.在pH～1的硝酸介质,以2×10~(-4)M双硫腙四氯化碳溶液萃取二次,回收率可达90%以上.本法可测定铝中2×10~(-6)%以上的银.
The catalytic effect of silver on manganese-persulfate reaction is well known.In this paper, it was found through experiments that under certain conditions, the reaction rate (reflected by the concentration of MnO 4 - produced by the reaction) is proportional to the silver ion concentration. By this reaction Successfully determined ultra-trace silver in high-purity aluminum.When the concentration of manganese ions was determined to be 6 × 10 -4 M, the potassium persulfate concentration was 1.85 M, the acidity of phosphoric acid was kept at 1.44 M, the total volume was 10 mL, When the bath is heated for 7 minutes, the reaction rate is proportional to the concentration of silver ions, and when the Ag value is in the range of 0-4 × 10 -7 M, the separation and concentration of silver in aluminum is extracted by dithizone Method in the pH ~ 1 nitric acid medium, with 2 × 10 ~ (-4) M dithizone solution of carbon tetrachloride extracted twice, the recovery rate of up to 90%. This method can be determined aluminum 2 × 10 ~ (-6)% of silver above.