Removal of arsenic(V) ions from aqueous media by adsorption on multiwall carbon nanotubes thin film using XRF technique

Abstract

A solid phase extraction using multiwalled carbon nanotubes, modified with a tertiary amine, ALIQUAT 336, has been developed as a preconcentration technique for the determination of trace amounts of As(V) in water samples. After "batch-based mode" As(V) adsorption on ALIQUAT 336-Multiwalled carbon nanotubes, determinations were made directly on the solid by X-Ray Fluorescence spectrometry, which reduces the number of reagents used and minimizes the sample handling. The method herein described combines the advantages of solid phase extraction with the benefits of any X-Ray Fluorescence method associated to the large areas held by the carbon nanotubes, which make them a promising solid sorbent for preconcentration procedures. The enrichment factor was calculated considering that the thin film obtained from the 100 mL solution of 1000 μg L-1 As had a final thickness of 0.04 mm and a final diameter of 16.7 mm, the volume deposited on the pellet was 0.0088 cm3. Thus the preconcentration factor obtained was 104 fold, which represented a highly satisfactory value for trace analysis by X-Ray Fluorescence. Satisfactory results were obtained for the determination of arsenic in samples of the standard reference material "NIST 1643e - Trace Elements in Water and drinking water".