Salt-Assisted Bulk Liquid Membrane and Flame Atomic Absorption Spectrometry for the Separation and Determination of Chromium(VI)

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.

Keywords:

• Bulk membrane
• cetyltrimethylammonium bromide
• chromium
• flame atomic absorption spectrometry