Assessment of nanocomposite alumina supported on multi-wall carbon nanotubes as sorbent for on-line nickel preconcentration in water samples

Abstract

The performance of Al 2O 3/MWCNT nanocomposite as a new sorbent for Ni(II) preconcentration from water samples, using a flow injection system coupled to flame atomic absorption spectrometry, is described in this study. The characterization of the nanocomposite was carried out by using thermogravimetric analysis (TG), BET surface area, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The analytical procedure involved the preconcentration of 20 mL Ni(II) solution buffered with 0.24 mol L −1 amoniacal buffer at pH 9.0 through 50 mg of the nanocomposite packed into a minicolumn, followed by the elution in countercurrent using 1.0 mol L −1 HNO 3 solution at flow rate of 5.0 mL min −1. Factors involved in the flow and chemical performance of the system were optimized by means of factorial design. The method provided a preconcentration factor of 20.9, linear range varying from 13.6 up to 230.0 μg L −1 and detection limit of 4.1 μg L −1 under optimized conditions. The proposed method was validated from recovery tests for Ni(II) determination in water samples, whose values ranged from 95.7 up to 99.1%, thus confirming the accuracy of the proposed method and the feasibility of Al 2O 3/MWCNT nanocomposite in the field of solid-phase preconcentration procedures.