Efficient removal of Pb(II)/Cu(II) from aqueous samples by a guanidine-functionalized SBA-15/Fe3O4

Abstract

A mesoporous guanidine functionalized Santa Barbara Amorphous-15(SBA-15)/Fe3O4 magnetic nanoadsorbent (Fe3O4@SBA-15-Gd) was prepared for decontamination of aqueous solutions from Pb(II) and Cu(II) heavy metals. The multistep fabrication route, including hydrothermal SBA-15 synthesis process, in situ magnetization by Fe3O4 magnetic nanoparticles (MNPs) (Fe3O4@SBA-15), post-synthetic method for composites’ modification by 3-aminopropyltriethoxysilane (APTES) (Fe3O4@SBA-15-NH2), and nucleophilic addition to cyanimide to prepare the magnetic Fe3O4@SBA-15-Gd nanoadsorbent was conducted. Moreover, the mesoporous SBA-15 was utilized to support Fe3O4 to diminish the MNPs agglomeration, and the guanidine functional group played a significant role in heavy metal adsorption. Various analyzing approaches were applied to validate the precise structure procedure. The novel adsorbent structure owes to the formation of bidentate chelating agent, guanidine groups, on the mesoporous SBA-15 support through a facile nucleophilic addition. An enhanced adsorption capability was acquired in this study. Hence, the Cu(II) and Pb(II) maximum adsorption capacity in optimized conditions reached ca. 344.82 mg/g and 303.03 mg/g. The obtained spherical-shaped MNPs in Fe3O4@SBA-15-Gd magnetic mesoporous nanoadsorbent presented average particles size ascertained to be ca. 63 nm. The Fe3O4@SBA-15-Gd nanoadsorbent rendered high porosity, high surface area, and abundant adsorption sites fabricated by cost-effective and accessible substance materials. Furthermore, the Freundlich model has explained the adsorption process, and the pseudo-second-order model describes the adsorption kinetics. The Fe3O4@SBA-15-Gd adsorbent was conveniently separated by an external magnet and regenerated three times without a notable decline in adsorption efficiency. Therefore, the prepared magnetic mesoporous nanoadsorbent is a privileged material for heavy metal elimination since it achieved remarkable adsorption capacity, yet more selectivity toward Cu(II) and Pb(II) adsorption via binding to the adsorbent’s chelating groups, and consequently, enhanced heavy metal ion amount decontamination.