Highly promoted removal of Hg(ii) with magnetic CoFe2O4@SiO2 core–shell nanoparticles modified by thiol groups

Abstract

A simple and environmentally friendly material, CoFe₂O₄@SiO₂–SH, was prepared successfully with CoFe₂O₄ nanoparticles coated by SiO₂ which was further functionalized with thiol groups (–SH). CoFe₂O₄@SiO₂–SH nanoparticles were structurally and thermally characterized. The results show that the additive of 3-mercaptopropyltriethoxysilane was successfully grafted onto CoFe₂O₄@SiO₂. The affecting factors, including pH, adsorbent dosage, and the initial concentration of Hg Hg(II) and coexisting ions were fully investigated and well elucidated. The fitting of adsorption kinetics and isotherm model indicated a good match with pseudo-second-order kinetics and Freundlich models. The Langmuir adsorption capability realized 641.0 mg g⁻¹. The data of thermodynamics illustrated that the removal for Hg(II) was exothermic and spontaneous. Last, an application evaluation of the material was also carried out. The adsorbent can achieve a quick and effective separation via a magnetic field after adsorption. Hence, the CoFe₂O₄@SiO₂–SH material will be a favorable and promising adsorbent to remove Hg(II) from water.