Hemimicelle capped functionalized carbon nanotubes-based nanosized solid-phase extraction of arsenic from environmental water samples

The end functionalization of CNTs can introduce oxygen-containing negatively functional groups such as -COOH, -OH, or -C=O on their surface site. If cationic surfactant such as cetyltrimethylammonium chloride (CTAC) was added to the functionalized CNTs, then interactions such as hydrophobic and ion may lead to formation of hemimicelle/admicelle aggregates on the CNTs, a new kind of adsorbent namely, the hermimicelle capped CMMWCNTs, is obtained. The application of the hemimicelle cappe carbon nanotubes-based nanosized solid-phase extraction (SPE) adsorbents in environmental analysis reported for the first time using arsenic as model target. The effect of adsorption and desorption conditions for arsenic including the amount of surfactant, initial pH of sample solution, the ultrasonic time of sample solution, the amount of electrolyte, flow rate, eluent and its amount were investigated an optimized prior to its determination by atomic fluorescence spectrophotometry (AFS). Arsenic can be quantitatively retained on the hernimicelle capped CMMWCNTs at pH 5-6 from sample volume up to 500 mL and then eluted completely with 2 mol L-1 HNO3 in the presence of 10 mg L-1 CTAC.The method detection limit for arsenic determination with AFS detection was 2 ng L-1, and the relative standard deviation (RSD, n = 11) was 5.3% at the 0.5 mu,g L-1 level. The recoveries of arsenic in the spiked environment water samples ranged from 94% to 104.29% with 500 mL of water sample. The proposed method has been applied successfully to the analysis of arsenic in aqueous environmental samples, which demonstrated the hernimicelle capped CMMWCNTs can be an excellent SPE adsorbents for arsenic pretreatment are enrichment from real water samples. (C) 2008 Elsevier B.V. All rights reserve.