4-(5-氯-2-吡啶)-偶氮-1,3-二氨基苯光度法测定电镀废水中的微量镍(Ⅱ)

Spectrophotometric Determination of Nickel(Ⅱ) in Electroplating Wastewater with 4-(5- Chloro-2-Pyridyl)-Azo-1,3-Diaminobenzene

4-(5-氯-2-吡啶)-偶氮-1,3-二氨基苯(5-Cl-PADAB)可与镍发生灵敏的显色反应,生成稳定的配位化合物。基于此建立了一种测定电镀废水中微量镍的光度法。结果表明:在2.0 mol/L HCl介质中,5-Cl-PADAB与Ni(Ⅱ)反应生成摩尔比2∶1的稳定配位化合物,其最大吸收波长为565 nm,表观摩尔吸光系数为6.42×104 L/(mol.cm),Ni(Ⅱ)含量在0～1.0 mg/L内符合比尔定律;该方法用于测定电镀废水中微量镍,结果与催化-分光光度法相符,相对标准偏差小于4.0%,加标回收率为98.5%～101.8%。

A spectrophotometric method was established to determine Ni(II) in electroplating wastewater, based on the sensitive coloring reaction of Ni(II) with 4-(5-chloro-2-pyridyl)-azo-1,3-diaminobenzene (5-Cl-PADAB) to generate stable coordination compound. It was found that, in 2.0 mol/L HCl medium, 5-Cl-PADAB reacted with Ni(II) to form a stable complex with a molar ratio of 2∶1. The complex had a maximum absorption at 565 nm and an apparent molar absorptivity of 6.42×104 L/(mol·cm). Beer’s law was obeyed in a Ni(II) concentration range of 0~1.0 mg/L. When the present method was applied to determine amounts of nickel in electroplating wastewater, results comparable to those determined by catalytic spectrophotometric method were obtained, with the relative standard deviation being less than 4.0% and the recoveries of samples being within 98.5%~101.8%.