Synthesis of -thiazole Schiff base modified SBA-15 mesoporous silica for selective Pb(II) adsorption

TLDR: In this article, two kinds of thiazole Schiff base modified mesoporous silica, SBA-NS and SBA -ENS, were prepared by modifying SBA 15 with aminopropyl and [2-aminoethylamino]-propyl groups, respectively, and then followed by Schiff condensation with 2-aldehyde-thiazole.

Abstract: Background The selective removal of Pb(II) ions is meaningful not only to the waste water treatment but also the lead recycling. Methods In this study, two kinds of thiazole Schiff base modified mesoporous silica, SBA-NS, SBA-ENS, were prepared by modifying SBA-15 with aminopropyl and [2-aminoethylamino]-propyl groups, respectively, and then followed by Schiff condensation with 2-aldehyde-thiazole. The effects of pH, time, ions concentration, and temperature on the Pb(II) adsorption performance were investigated. Significant Findings The kinetics analysis and adsorption isotherms revealed that the overall Pb(II) adsorption process by the two adsorbents was more consistent with the pseudo-second-order kinetic model and Langmuir isotherm model. The thermodynamic parameters showed spontaneous and exothermic Pb(II) adsorption nature onto SBA-NS and SBA-ENS. Compared with amino modified silica precursors, SBA-NS and SBA-ENS exhibited improved adsorption selectivity for Pb(II) in binary metal ion systems with co-existing cations. Besides, the adsorption behavior is not affected by the ionic strength, and the adsorbents can be easily reused without significant loss in of Pb(II) removal efficiency. The density functional theory method demonstrated that the imine N atoms on the two adsorbents played a dominant role during the Pb(II) sorption process.