4-(5-氯-2-吡啶偶氮)-1,3-苯二胺分光光度法测定火法冶炼镍基体料中的钴

Determination of cobalt in fire smelting nickel substrate material by 4-(5-chloro-2-pyridylazo)-1,3-phenylenediamine spectrophotometry

研究了以4-(5-氯-2-吡啶偶氮)-1,3-苯二胺(5-Cl-PADAB)分光光度法测定火法冶炼镍基体料中钴的最佳实验条件。探讨了合适的样品溶液制备方法,对比了不同酸度下络合物的生成情况,确定了最适宜的检测波长,以及显色液加入量等。实验表明,以合适量的柠檬酸铵溶液作为掩蔽剂,可以消除Ni 2+、Cr3+、Cu2+等元素对钴的干扰;Fe3+由于含量太高,消除其干扰时,除柠檬酸铵掩蔽外,还需在绘制校准曲线时向标准溶液中加入与样品中相当量的Fe3+予以消除。在优化条件下,钴的浓度在0.005%～0.5%内符合比尔定律。将本方法应用于实际样品分析,所得结果与原子吸收光谱法(AAS)一致,实验室内平行测定11次结果的相对标准偏差在1.6%～3.2%之间。该法可应用于火法冶炼镍基体料中钴的分析,为行业标准的制定奠定了一定基础。

The optimal determination conditions of cobalt in pyrometallurgical nickel-based materials by 4-（5-chlor-2-pyridineazo）-1,3-phenylenediamine（5-Cl-PADAB） spectrophotometry were studied.The proper sample solution preparation method was investigated.The generation of complex under different acidity conditions was compared,and the optimal determination wavelength and dosage of coloring solution were obtained.The results showed that the interference of Ni2＋,Cr3＋ and Cu2＋ to cobalt could be eliminated by adding proper amount of ammonium citrate solution as masking agent.Since the content of Fe3＋ was too high,besides of the addition of ammonium citrate solution,equivalent Fe3＋ in sample solution should be added into standard solution to plot calibration curve to eliminate its interference.Under the optimal conditions,the Beer＇s law was obeyed for the concentration of cobalt in range of 0.005%-0.5%.The proposed method was applied to the analysis of actual sample,and the results were consistent with those obtained by atomic absorption spectrometry（AAS）.The relative standard deviation（RSD,n=11） was 1.6 %-3.2 %.This method could be used for the analysis of cobalt in pyrometallurgical nickel-based materials,and it laid a certain foundation for the establishment of industrial standard.