过硫酸铵-丁二酮肟光度法测定红土镍矿中的镍

红土镍矿样品用适宜比例的HCl-HNO3-HF-HClO4混合酸低温消解,待样品溶解完全后在NaOH介质中,以过硫酸铵作氧化剂将Ni2+氧化为Ni4+,使Ni4+与丁二酮肟生成可溶性酒红色络合物,采用分光光度法测定镍的含量。样品溶液中仅通过加入酒石酸钾钠作掩蔽剂,就可消除红土镍矿中其他基体元素对镍测定的干扰,避免了萃取分离操作和有机试剂对环境的污染。在优化的酸碱度、试剂加入顺序及用量、显色时间等实验条件下,镍的线性范围为0～2.0μg/mL,方法检出限为0.1 mg/g,精密度为(RSD)为0.75%～1.69%,加标回收率为95.4%～102.7%。方法用于分析红土镍矿中镍的含量,测定结果与电感耦合等离子体发射光谱法相符。该方法简便,稳定性好,仪器价格低廉,可用于批量红土镍矿样品中镍的快速准确测定。

Determination of Ni in Nickel Laterite Ores by Ammonium Persulfate-Dimetylglyoxime Spectrophotometry

A spectrophotometry has been developed for determination of Ni content in nickel laterite ores.The sample was dissolved by mixed acids of HCl,HNO3,HF and HClO4 with appropriate proportions.After being completely dissolved,the salt was dissolved with 50% HNO3.Ni2+ and was oxidized to Ni4+ by ammonium persulfate in a NaOH medium.Ni4+ reacted with dimetylglyoxime to form a soluble red-wine complex compound which was measured by spectrophotometry to obtain the Ni content.Interferences of other matrix elements in the nickel laterite ores were eliminated by using potassium sodium tartrates as the masking agent.Experimental conditions including pH value,sequence of adding reagents,reagent consumption and coloration time were studied.Under the selected experimental conditions,the linear range was 0-2.0 μg/mL,and the limit of detection was 0.1 mg/g.The determination results were in agreement with those obtained by Inductively Coupled Plasma-Atomic Emission Spectrometry(ICP-AES).The relative standard deviations(RSD) were 0.75%-1.69% and the recoveries for Ni were 95.4%-102.7%.The experimental results indicate that this method is stable and reliable,and it can be applied to rapidly and accurately determine Ni in nickel laterite ores.