Impedimetric Determination of Uranyl Based on a Modified Electrode by Magnetic Hydroxyapatite Nanocomposite

Abstract

Herein, impedimetric determination of uranyl ions (UO22+) by using a modified magnetically carbon paste electrode (MCPE) with hydroxyapatite magnetic nanoparticles (MNP/HAP) was reported for the first time. Firstly, magnetic nanoparticles were synthesized and then hydroxyapatite nanoparticles were precipitated on them via the chemical precipitation method. After that, the MCPE electrode was modified by MNP/HAP to collect UO22+ from an aqueous solution. Modification of the electrode and its interaction with UO22+ ions were studied by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) in the presence of a Fe[(CN)6]3-/4- and PBQ/H2Q, as a redox probe. Electrochemical impedance change against the concentration of UO22+ ions in the presence of electrochemical probes was selected as an analytical signal of this procedure. Optimized response for modified electrode with 100 µg MNP/HAP was observed after preconcentration of UO22+ for 30 min at pH 7, and for 35 min at pH 6 for Fe[(CN)6]3-/4- and PBQ/H2Q as a redox probe, respectively. The applicability of the impedimetric method in the determination of uranyl by using the proposed electrode was shown by drawing a linear calibration curve in the concentration range between 1×10-10 to 4×10-4 M of UO22+ in the presence of both probes. Detection limits as 7.58×10-11 M and 9.12×10-11 M and relative standard deviation (RSD) for n = 5 as %0.82 and % 1.05 were observed for Fe[(CN)6]3-/4- and PBQ/H2Q as a redox probe, respectively.

Keywords

• impedimetry
• determination of uo22+
• magnetic nanoparticles
• hydroxyapatite