分光光度法测定铀矿冶废水中微量总铬和六价铬

SPECTROPHOTOMETRIC DETERMINATION OF TOTAL CHROMIUM AND HEXAVALENT CHROMIUM IN WASTE WATER FROM THE URANIUM MINING AND HYDROMETALLURGICAL MILL

摘要: 本法采用二苯碳酰二肼试剂在酸性条件下与六价铬反应.生成二苯碳酰二肼铬,化合物呈紫红色。在波长540nm处有最大吸收峰。对总铬测定则采用高锰酸钾氧化,使铬全部转化为六价,然后再与二苯碳酰二胼反应。实验在大量钙、镁、硫酸根、硝酸根,铵根,以及ppm级的砷、铅、镉、汞、铝、铜、铁、锰、硅、氟等离子存在下测定铬无干扰,测定铬范围为0.020—0.200mg/l,精密度±5％。样品重加回收率95-105％,对样品稍加处理便能测定,方法简便。

Abstract: Hexavalent chromium is determined by reaction with diphenylcarbazide in acid condition, producing a red violet color compound. There is a sharp absorbency at 540nm. If total chromium is to be determined, it is necessary to oxidize the Cr(Ⅲ) to Cr(Ⅵ) by potassium permanganate before reacting with diphenylcarbazide. The concentration of Ca(Ⅱ) , Mg(Ⅱ) , SO42--, NO3-, and NH4+ up to 500mg/l, and the concentration of As(Ⅴ) , Pb(Ⅱ) , Hg(Ⅱ), Al(Ⅲ) , Cu(Ⅱ) , Fe(Ⅲ) , Mn(Ⅱ) , Si(Ⅳ) and F- up to lmg/ml can be tolerated. The range of chromium from 0.02-0.200mg/ml can be determined. The precision of the method is ±5%. The recovery of added standard sample is 95-105%.