TEPA-functionalized magnetic mesoporous composites as a novel adsorbent for the removal Cr(III)-EDTA in complex solution

A novel tetraethylenepentamine (TEPA) functionalized magnetic mesoporous silica adsorbent (FNMs/TEPA) was prepared for adsorption of Cr(III)-EDTA from wastewater. Characterization of the prepared adsorbent certified that TEPA was modified onto the magnetic mesoporous silicon (FNMs), while FNMs/TEPA maintained the ordered mesoporous and pristine magnetic properties. The batch adsorption experiments demonstrated that TEPA significantly enhanced the removal capacity of the adsorbent for Cr(III)-EDTA. FNMs/TEPA exhibited an excellent adsorption property (13.84 mg∙g–1) at pH 4.0. Even in the existence of high concentrations of coexisting ions and organic acids, the adsorption performance of FNMs/TEPA was stable. Experimental characterization and density functional theory (DFT) demonstrated that the adsorption of Cr(III)-EDTA was ascribed to the electrostatic interaction, hydrogen bonding, and complexation between Cr(III)-EDTA and amino groups on the adsorbent surface. The analysis of the Independent Gradient Model (IGMH) shown that electrostatic interaction is the main mode of action in the adsorption process. Moreover, FNMs/TEPA demonstrated remarkable reusability in three regeneration cycles. These findings indicated that FNMs/TEPA possessed excellent application prospect in the disposal of wastewater containing Cr(III)-EDTA.