Determination of Chromium and Nickel in Water Samples by Zinc Oxide Nanoparticle–Chitosan: Equilibrium, Kinetic and Thermodynamic Studies

Abstract

This study describes the preparation of zinc oxide nanoparticle–chitosan as a solid-phase adsorbent for separation and preconcentration of trace amount of chromium and nickel from environmental water samples and their determination by inductively coupled plasma optical emission spectrometry. Important factors including pH, amount of adsorbent, amount of 1-(2-pyridylazo)-2-naphthol, sample volume, eluent concentration and extraction time were investigated and optimized. The equilibrium data according to the Freundlich’s and Langmuir models were processed. The results showed that the equilibrium data were well fitted with Langmuir isotherm model. The best fit of adsorption kinetics was attained with a second-order equation. Under the optimum conditions, the detection limits for chromium and nickel were 0.041 and 0.039 µg L−1, respectively, and the relative standard deviations (RSD %) were 1.5% and 1.3% (n = 10, c = 50 µg L−1) for chromium and nickel, respectively. This procedure was then used for preconcentration and determination of target compounds from environmental water samples.