分散液液微萃取-分光光度法测定电镀废水中铬(Ⅵ)

Determination of Trace Chromium(Ⅵ) in Electroplating Wastewater by Spectrophotometry with Dispersive Liquid-liquid Microextraction

用三氯甲烷作萃取剂,无水乙醇作分散剂,依据二苯碳酰二肼分光光度法与铬(Ⅵ)能形成紫红色可溶性络合物,建立分散液液微萃取-分光光度法测定痕量铬(Ⅵ)的分析方法,优化了分散液液微萃取富集条件和分光光度法的测定参数。在最佳实验条件下,铬(Ⅵ)质量浓度在5~60 ng/mL时与吸光度服从比尔定律,回归方程为A=0.011 7ρ+0.005 6,相关系数r=0.999 3,检出限为0.46 ng/mL。实验讨论了20多种共存离子的影响。采用实验方法测定电镀废水中铬(Ⅵ),相对标准偏差(RSD,n=6)为1.6%~2.1%,加标回收率为97.8%~103.0%,测得电镀废水中六价铬含量与原子吸收光谱法的测定结果基本一致。

Taking trichlorom ethane as the extraction solvent and waterless ethanol as the disperser,based on the principle that chromium(Ⅵ)can form a fuchsia soluble complex with dibenzene carbon diazepam,a method-spectrophotometry with dispersive liquid-liquid microextraction is proposed,which optimizes the parameters for both the enrichment of dispersive liquid-liquid microextraction and the determination of spectrophotometry.Under the optimal conditions,the mass concentration of chromium(Ⅵ)within the range of5~60 ng/m L and the absorbance conform to Beer’s law,with linear equation A=0.0117ρ+0.0056,correlation coefficient of 0.9993 and the detection limit of 0.46 ng/mL.The interferences of more than 20 foreign ions are tested.Using the proposed method,the test results show that the relative standard deviations(RSD,n=6)are1.6%~2.1%,the recovery rates are 97.8%~103.0%,and the content of chromium(Ⅵ)in electroplating wastewater is basically the same with that obtained by using atomic absorption spectrometry.