微波消解-亮绿SF-过氧化氢体系催化动力学光度法测定铜尾矿中痕量铜(Ⅱ)

Determination of trace copper(Ⅱ) in copper tailing by catalytic kinetic spectrophotometry with microwave digestion-light green SF-hydrogen peroxide system

研究了在稀HNO3介质中,以十六烷基三甲基溴化铵(CTMAB)表面活性剂为增敏剂,痕量铜(Ⅱ)可催化过氧化氢氧化亮绿SF褪色,据此建立了催化动力学光度法测定痕量铜的新方法。对分析方法进行优化,确定褪色检测波长为635nm。同时,建立了反应动力学方程,确定此反应对亮绿SF试剂为零级反应,对痕量铜为一级反应。在最优化条件下,方法的检出限为0.23×10-9g/mL,Cu2+的质量浓度在0～20ng/mL范围内与吸光度变化值(ΔA)呈良好的线性关系。经使用掩蔽剂可以有效地消除其它共存离子的干扰。方法结合优化的微波消解技术对铜尾矿样品进行处理,并用于两种铜尾矿中痕量铜(Ⅱ)的测定,相对标准偏差分别为3.8%和2.4%,加标回收率为97%～99%。

A novel method for the catalytic kinetic spectrophotometric determination of copper（Ⅱ） was proposed based on the catalytic effects of trace copper （II） on the fading reaction of light green SF oxidized by H2O2 in the presence of dilute nitric acid with CTMAB as sensitizer. The experimental method was optimized, and the detection wavelength was selected as 635 nm. Meanwhile, the kinetic equation of the reaction was also created. The results showed that this reaction was zero order reaction for light green SF and first order reaction for trace copper. Under the optimal conditions, the detection limit of this method was 0.23×10-9 g/mL. The the changes of absorbance （ΔA） had good linearity with the mass concentration of Cu2＋ in the range of 0-20 ng/mL. The interference of other coexisting ions could be effectively eliminated by adding proper masking reagents. Combined with optimized microwave digestion technology, this method has been applied to the determination of trace copper（Ⅱ） in two kinds of copper tailings samples. The relative standard deviations （RSD） were 3.8 % and 2.4 %, respectively, and the recoveries were 97 %-99 %.