Solid phase extraction of chromium(VI) using Aliquat336 immobilized on a thin film of multiwall carbon nanotubes

Abstract

We report on a novel and selective method for the preconcentration and determination of Cr(VI) in aqueous samples. Cr(VI) is adsorbed - in a "batch mode" - on multiwalled carbon nanotubes covered with Aliquat 336 and then determined directly, i. e., on the solid, by X-ray fluorescence spectrometry. This reduces the number of reagents and minimizes sample handling. The method combines the advantages of solid-phase extraction with the benefits of the XRF method in that the large areas required by the carbon nanotubes make them a promising solid sorbent for preconcentration. The enrichment factor was calculated after considering that the thin film obtained from the 10 mL solution of 1 mg L -1 of Cr(VI) has a real thickness of 0. 04 mm and a final diameter of 16. 7 mm, so that the volume deposited on the pellet is 0. 0088 cm 3 and the preconcentration factor is 1000.