Abstract

Due to the common use of chromium in many industrial applications, as well as its potential release into water sources, the quantification of chromium in environmental samples has great importance. In this work, a novel and fast salt-assisted bulk membrane extraction (SA-BME) combination with flame atomic absorption spectrometry (FAAS) was proposed for the separation and preconcentration of Cr(VI) in water samples. The transport of Cr(VI) was performed using cetyltrimethylammonium bromide (CTAB) as the mobile carrier dissolved in kerosene/chlorofrom organic membrane at room temperature. After this process, Cr(VI) was reduced to Cr(III) in a receiving phase using an acidified iron(II) sulfate. In aqeous solutions, total chromium was determined as Cr(VI) after the oxidizing Cr(III) to Cr(VI) using potassium permanganate in acid medium and finally total chromium was measured by FAAS. The analytical parameters affecting the separation and mass transfer of Cr(VI) were optimized. With 20 µg L⁻¹ of Cr(VI) in the feed phase, the extraction efficiency was quantitative using a 50 minute extraction time. Under the optimum conditions, the linearity (R² = 0.9994) was from 7 to 290 µg L⁻¹, the limit of detection 2.3 µg L⁻¹ and the enrichment factor 35 for Cr(VI). Common cation and ions in water samples did not interfere with the separation and determination of Cr(VI). The developed SA-BME method has been successfully applied for the determination of Cr(VI) in stream, sea and waste water with good recoveries.

摘要

由于铬在许多工业应用中的普遍使用以及其潜在的释放到水源中的能力，因此对环境样品中的铬进行量化非常重要。在这项工作中，提出了一种新颖，快速的盐辅助大体积膜萃取（SA-BME）与火焰原子吸收光谱法（FAAS）的组合，用于水样品中Cr（VI）的分离和预富集。Cr（VI）的运输是使用十六烷基三甲基溴化铵（CTAB）作为移动载体在室温下溶解于有机膜中的煤油/氯中进行的。此过程之后，在接收阶段，使用酸化的硫酸铁（II）将Cr（VI）还原为Cr（III）。在水溶液中，在酸性介质中使用高锰酸钾将Cr（III）氧化为Cr（VI）后，将总铬确定为Cr（VI），最后通过FAAS测定总铬。优化了影响Cr（VI）分离和传质的分析参数。含20 µg L进料相中的Cr（VI）^-1，使用50分钟的萃取时间可定量地提取萃取效率。在最佳条件下，线性度（R ² = 0.9994）为7至290 µg L ^-1，检出限为2.3 µg L ^-1，Cr（VI）的富集系数为35。水样品中的常见阳离子和离子不会干扰Cr（VI）的分离和测定。所开发的SA-BME方法已成功地用于测定溪流，海水和废水中的Cr（VI），回收率高。