Magnetic Mn2O3 nanocomposite covered with N,N'-bis(salicylidene)ethylenediamine for selective preconcentration of cadmium(II) prior to its quantification by FAAS.

Abstract

This article describes a method for highly selective preconcentration of Cd(II) via magnetic Mn2O3 coated by N,N'-bis(salicylidene)ethylenediamine (BSED). The metal oxide components were prepared via combining sol-gel and precipitation methods. Then, BSED was added as the third component of the composite. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, alternating gradient force magnetometry, and Fourier transform infrared spectroscopy were applied to characterize the materials. BSED selectively forms a complex with Cd(II), and the sorbent can then be magnetically separated. The preconcentration conditions were optimized as pH value (4.0 ± 0.5), sorbent amount (30mg), adsorption time (20min), eluent 2 MHNO3), eluent volume (1.5mL) and desorption time (4min). The quantification of Cd(II) was done by flame atomic absorption spectroscopy. Themethod has the following figures of merit: (a) a detection limit of 320µgL-1, (b) a relative standard deviation of 1.1%, (c) an enhancement factor of 36, (d) a preconcentration factor of 33, and (e) a linear dynamic range that extends from 10 to 120μgL-1. Other features include the use of safe reagents, fast and simple preparation, high selectivity and reliable analytical performance. The effects of potentially interfering ions were examined. The Dubinin-Radushkevich model and the pseudo second-order model are found to fit the adsorption behavior. The absorption is spontaneous and exothermic. The method was successfully applied to the determination of Cd(II) in (spiked) fruit samples. Graphical abstract Schematic presentation of a nanocomposite (Fe3O4 - Mn2O3 - Schiff base) that was prepared from MnCl2, H2O2, FeCl2, FeCl3, NH3, salicylaldehyde, ethylenediamine and tetraethylammonium hydroxide for the magnetic solid phase extraction of cadmium at trace levels.