Facile Strategy for Fabricating an Organosilica-Modified Fe3O4 (OS/Fe3O4) Hetero-nanocore and OS/Fe3O4@SiO2 Core–Shell Structure for Wastewater Treatment with Promising Recyclable Efficiency

The development of a sustainable process for heavy metal ion remediation has become a point of interest in various fields of research, including wastewater treatment, industrial development, and health and environmental safety. In the present study, a promising sustainable adsorbent was fabricated through continuous controlled adsorption/desorption processes for heavy metal uptake. The fabrication strategy is based on a simple modification of Fe3O4 magnetic nanoparticles with organosilica in a one-pot solvothermal process, carried out in order to insert the organosilica moieties into the Fe3O4 nanocore during their formation. The developed organosilica-modified Fe3O4 hetero-nanocores had hydrophilic citrate moieties, together with hydrophobic organosilica ones, on their surfaces, which facilitated the further surface coating procedures. To prevent the formed nanoparticles from leaching into the acidic medium, a dense silica layer was coated on the fabricated organosilica/Fe3O4 (OS/Fe3O4). In addition, the prepared OS/Fe3O4@SiO2 was utilized for the adsorption of cobalt(II), lead(II), and manganese(II) from the solutions. The data for the adsorption processes of cobalt(II), lead(II), and manganese(II) on OS/(Fe3O4)@SiO2 were found to follow the pseudo-second-order kinetic model, indicating the fast uptake of heavy metals. The Freundlich isotherm was found to be more suitable for describing the uptake of heavy metals by OS/Fe3O4@SiO2 nanoparticles. The negative values of the ΔG° showed a spontaneous adsorption process of a physical nature. The super-regeneration and recycling capacities of the OS/Fe3O4@SiO2 were achieved, comparing the results to those of previous adsorbents, with a recyclable efficiency of 91% up to the seventh cycle, which is promising for environmental sustainability.