Solid phase extraction of Mercury from aqueous solutions byfunctionalized magnetic core-shell

The objectives of this study are to prepare the thiol functionalized Fe3O4@SiO2 core/shell magnetic nanoparticles for removal of ultra-trace amount of Hg2+ from aqueous samples. The Fe3O4 nanoparticles synthesized by the facile co-precipitation method[1] were coated with SiO2 via the stober method[2] and further modified by the 3-(Trimethoxysilyl)-1-propantiol to prepare Fe3O4/SiO2–Si- (CH2)3-SH nanoparticles[3]. The morphology of this nanoparticle was characterized by scanning electron microscopy (SEM), and FT-IR. The adsorption of Hg2+ ions was examined by batch equilibrium technique. The effect of initial Hg2+ concentration, pH value, eluent concentration and volume, contact time, and coexisting ions on the efficiency of Hg2+ removal have been investigated. This nanosorbent can be easily dispersed in aqueous samples and separated from aqueous solution by applying an external magnet. The mercury analysis was performed by continuous-flow cold vapor atomic absorptionspectrometry. Each parameter affecting the extraction and preconcentration processes was carried out. The optimum conditions were found to be 55 mg of sorbent, pH of 6.5, 12 min for adsorption time, 5 mL of HCl (0.1 mol L−1)/thiourea (2% w/v) as the eluent and 1000 mL for breakthrough volume. An excellent linearity was achieved in the range of 0.10–90 ng mL–1 (R2 = 0.987) at a preconcentration factor of 175.The limit of detection and quantification were achieved as 0.09 ng mL−1 and 0.17 ng mL−1, respectively. A good repeatability was obtained with the relative standard deviation (RSD) of 4.7%.