催化动力学光度法测定工业废水中的Cr(Ⅵ)

Determination of Cr(Ⅵ) in industrial wastewater by catalytic kinetic spectrophotometry

采用β-环糊精作为H_2O_2氧化茜素红褪色反应的增敏剂,建立了催化动力学光度法测定工业废水中Cr(Ⅵ)的新方法。该方法最佳反应条件为:反应体系总体积25 m L,0.1 mol/L的H_2SO_4溶液加入量2.0 m L,1.0×10^(-3) mol/L茜素红溶液加入量1.5 m L,30%的H_2O_2溶液加入量4.0 m L,100 g/L的β-环糊精溶液加入量3.0 m L。在最大吸收波长554 nm处测定反应前后溶液的吸光度,Cr(Ⅵ)的质量浓度与吸光度差值(ΔA)在4.0×10^(-4)~5.4×10^(-2) mg/L范围内符合比尔定律,线性回归方程为:ΔA=18.52ρ+0.018,相关系数为0.996 6,检出限为3.5×10^(-4) mg/L,加标回收率为99.46%~101.3%,6次测定的相对标准偏差小于等于2.4%。该法的测定结果与GB/T 7467—1987中的二苯碳酰二肼分光光度法相近。

A new method for determination of Cr （Ⅵ） in industrial wastewater by catalytic kinetic spectrophotometry was developed using 13-cyclodextrin as sensitizer for alizarin red fading reaction by H202 oxidation. The optimum reaction conditions are as follows： system volume 25 mL, H2SO4 solution （0.1 mol/L） dosage 2.0 mL, alizarin red solution （1.0 × 10.3 mol/L ） dosage 1.5 mL, H2O2 solution （30%） dosage 4.0 mL, 13-cyclodextrin solution （100 g/L） dosage 3.0 mL. The absorbances of the solution before and aRer reaction were determined at the maximum absorption wavelength 554 nm. The relation of Cr （Ⅵ） mass concentration and the absorbance difference （AA） accords with Beer＇ s law in the range of 4.0 × 104-5.4 × 10.2 mg/L with the linear regression equation of AA=18.52p＋ 0.018 and the correlation coefficient of 0.996 6. The detection limit of the method is 3.5 × 10-4 mg/L. The recovery of added standard material is 99.46%-101.3%. The relative standard deviation is no more than 2.4% （n=6）. The determination results are similar to those of diphenylcarbazide spectrophotometric method in GB/T 7467-1987.