分光光度法测定电镀废水中的痕量Cr(Ⅵ)

Spectrophotometric determination of trace chromium(Ⅵ) in electroplating wastewater

研究了硝酸介质中 ,Cr2 O2 -7氧化偶氮胂Ⅲ褪色反应的最佳条件 ,如测量波长、反应介质、试剂用量、反应温度及时间等和工作曲线 ,给出了相应的测定方法。结果表明 :该褪色反应具有很高的灵敏度 ,摩尔吸光系数达 3 9× 10 6L/ (mol·cm) ,最大吸收波长 5 2 5nm ,线性范围为 :0～ 4 .0 μg/ 2 5mL ,检出限为 6 6× 10 -9g/mL。从而建立了光度法测定痕量Cr(Ⅵ )的新方法。

The fading reaction of arsenazo Ⅲ with Cr 2O 2- 7 in the nitric acid was studied, and a new spectrophotometric method with high sensitivity for Cr(Ⅵ) determination was established. The molar absorptivity was 3.9×10 6 L/(mol·cm), the absorption maximum was at 525 nm, the linear rang was 0～ 4 μg/(25mL), and the detection limit was 6.6×10 -9 g/mL. The optimal reaction conditions such as maximal absorption wavelength, medium, reagent dosage, tempreture, time and standard curve were studied, and satisfactory results were obtained in the trace Cr(Ⅵ) determination of electroplating wastewater.