Modification of Magnetic Graphene Oxide By An Earth-Friendly Deep Eutectic Solvent To Preconcentrate Ultratrace Amounts Pb(II) In Oil Seeds

Abstract

The aim of this article is presenting an earth-friendly deep eutectic solvent (DES) to preconcentrate ultratrace amounts of Pb(II) prior to its quantification by flame atomic adsorption spectroscopy. The synthesis of adsorbent started by preparing graphene oxide according to the modified Hammer’s method, followed by magnetization by Fe3O4 nanohemispheres. Magnetic graphene oxide was dispersed in a mixture of LiCl and urea at 60° via ultrasonication. All the materials are environmentally-friendly and the preparation strategy is energy efficient. X-ray diffraction, scanning electron microscopy, alternating gradient force magnetometer and Fourier-transform infrared spectroscopy were applied to characterize the products. Graphene oxide has a large surface area and could be functionalized with DESs through π-π interaction and electrostatic force. Urea has active negative sites, which garb heavy metals due to the interaction between negative and positive agents. Accordingly, this adsorbent (UreaLiCl-mGO) could be offered as a capable adsorbent to preconcentrate ultratrace amounts of Pb(II). Conditions were optimized, and under the optimum situation, (a) limit of detection of 99 × 10-8 g L-1, (b) relative standard deviation (n=5) of 1.3%, (c) preconcentration factor of 100 (d) linearity of dynamic range of 5.0 × 10-6 – 23 × 10-6 g L-1, (e) durability of 6 months and (f) reusability of 7 times prove applicability of the adsorbent. The tests of selectivity, effect of interference ions, swelling property, isotherm of adsorption, kinetic of adsorption and thermodynamic of adsorption were completely investigated. Four different oil seeds were successfully applied as real samples.