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Synthesis, characterisation and application of 4-Aminoazobenzene functionalised multiwalled carbon nanotubes as a novel and uniquely selective solid-phase extraction for determination of lead(II) in water samples

Multiwalled carbon nanotubes modified with 4-Aminoazobenzene was prepared and applied to the separation, preconcentration and determination of Pb(II) in aqueous solutions by inductively coupled plasma optical emission spectrometry. Characterisation of the surface modiﬁcation was performed on the basis of transmission electron microscopy, Fourier transform infrared spectra and elemental analysis. The effects of pH, the sample flow rate and volume, the elution condition and the interfering ions were examined using batch and column procedures in detail. Under the optimised conditions (pH 5.0, flow rate 2.0 mL min−1), Pb(II) retained on the column can be quantitatively eluted by 2.0 mL 0.1 mol L−1 HCl. An enrichment factor of 150 was accomplished. Common interfering ions did not interfere in both the separation and determination. The maximum adsorption capacity of the adsorbent at optimum conditions was found to be 46.8 mg g−1. The detection limit (3σ) was 0.28 μg L−1, and the relative standard deviation (RSD) was 2.1% (n = 11). The method was validated using certified reference materials, and has been applied for the determination of trace Pb(II) with satisfactory results.