A new nano-sorbent for fast and efficient removal of heavy metals from aqueous solutions based on modification of magnetic mesoporous silica nanospheres

Highlights: • Magnetic mesoporous silica nanospheres were functionalized with bis(3-triethoxysilylpropyl)tetrasulfide. • The functionalized mesoporous silica nanospheres had high surface areas. • High removal efficiencies of Hg(II), Pd(II), and Pb(II) were achieved with MSCMNPs-S₄. • The MSCMNPs-S₄ nanospheres show a good regeneration and reusability performance after five-cycle regenerations. - Abstract: In the present study, a new and efficient nanosorbent for the fast removal of heavy metal ions was prepared. The proposed nanosorbent was fabricated using Fe₃O₄ magnetic core shelled by mesoporous silica, and cetyltrimethylammonium bromide (CTAB) as surfactant template through a sol-gel process. The magnetic nanomaterial was further modified with bis(3-triethoxysilylpropyl)tetrasulfide (MSCMNPs-S₄). The final nanosphers were characterized by FT-IR, XRD, TGA, BET, SEM, TEM, DLS, VSM, EDX, and UV–Vis. The potential of the resultant mesoporous magnetite nanomaterials was investigated as a convenient and effective adsorbent for the removal of toxic heavy metal ions from aqueous solutions in a batch system. The effect of essential parameters on the removal efficiency including initial pH of sample solution, adsorbent amount, metal ion concentration, contact time and type and quantity of the eluent on the adsorption characteristics of the MSCMNPs-S₄ were studied. Under the optimized conditions, the proposed nanosorbent exhibited high adsorption capacity of 303.03, 256.41 and 270.27 mg g⁻¹ and maximum removal percentages of 98.8%, 96.4%, 95.7% for Hg(II), Pd(II) and Pb(II) ions, respectively. The mechanism of the adsorbtion was found to be in good agreement with the Langmuir isotherm model. Furthermore, the reusability investigation indicated that the MSCMNPs-S₄ could be used frequently at least for five cycles without any significant loss in its performance.