微乳液增敏催化光度法测定痕量铬的研究

研究了在微乳液(溴化十六烷基三甲基胺(CTMAB)/正戊醇/正庚烷/水)介质中,痕量铬(Ⅵ)催化过氧化氢氧化茜素红的褪色反应,建立了测定痕量铬的催化动力学新方法。在微乳液体系中,方法的灵敏度比在表面活性剂CTMAB体系中提高了72.5%,催化反应的表观活化能为55.7 kJ.mol-1。水浴温度升高,灵敏度显著提高,校准曲线在不同的反应温度下线性范围不同,在80℃反应温度下,线性范围为2.4~75μg.L-1,检出限达4.27×10-10g.mL-1,相对标准偏差为1.84%(n=11)。该法已应用于电镀废水中铬(Ⅵ)的测定,结果令人满意。

Kinetic Spectrophotometric Determination of Trace Chromium (Ⅵ) with Sensitized Function of Microemulsion

A sensitive catalytic spectrophotometric method for determining microg x L(-1) of chromium(VI) has been developed. The method, based on the catalytic effect of Cr(VI)on the oxidation of aligarin red with hydrogen peroxide, was monitored spctrophotornetrically in the medium of microemulsion which consists of CTMAB, n-pentanol, n-heptane and water. The variables affecting the rate of the reaction were investigated. The linearity range of the calibration graph is dependent on the reaction temperature. The sensitivity of this method is 72.5% higher in the microemulsion medium than in CTMAB medium. The apparent active energy of the catalytic reaction is 55.7 kJ x mol(-1). The calibration graph is linear for 2.4-75 microg x L(-1) Cr(VI)at 80 degrees C, the detection limit is 4.27 x 10(-10) g x mL(-1), and the relative standard deviation of eleven determinations of 60 microg x L(-1) Cr(VI)was 1.84%. The method has been successfully applied to the determination of chromium(IV) in the electroplating waste water.