Ion-imprinted mesoporous silica/magnetic graphene oxide composites functionalized with Schiff-base for selective Cu(II) capture and simultaneously being transformed as a robust heterogeneous catalyst

Abstract

Ascribing to the risk on public health and environment, as well as the extensive applications of copper, the highly selective capture and effective utilization of the recovered Cu(II) ion by using a multifunctional material are of significant practical interest. However, there remains an arduous challenge to the fulfillment of such tasks. In this study, using the mesoporous silica/magnetic graphene oxide composites (MS/MGO) as the support, 2-((2-(3-(trimethoxysilyl)propylamino)ethylimino)methyl)phenol (TPEMP) bearing Schiff-base as the functional monomer, surface Cu(II) ion-imprinted polymers (Cu(II)-IIPs) were fabricated and applied for the selective capture Cu(II) ion from aqueous media. Additionally, the reuse of the spent Cu(II) loaded adsorbent (SMS/MGO-Cu) to the catalytic application was also explored. The obtained samples were characterized by various techniques. The uptake of Cu(II) by Cu(II)-IIP-2 was tested through the study of pH effect, sorption isotherms and uptake kinetics, selective sorption, adsorbent regeneration. The results indicated the Cu(II)-IIP-2 had high selectivity and faster kinetic over reported adsorbents, with an equilibrium adsorption capacity of 195.3 mg/g at 298 k within 30 min. Sorption isotherms were well described by the Langmuir model, while the uptake kinetics was fitted by the pseudo-second order rate equation. In addition, the Cu(II)-IIP-2 could be recycled six times without any significant loss in adsorption capacity. Importantly, the best catalysis efficiency of SMS/MGO-Cu for the synthesis of 1-methyl-4-(p-tolyloxy)benzene was 95%. These results indicate the Cu(II)-IIP-2 can not only be applied to effectively remove Cu(II) ion from aqueous media, but also be used in heterogeneous catalytic organic synthesis reactions after sorption.