Ion-imprinted magnetic adsorbents for the selective capture of Cu(II) and their cascade application as heterogeneous recyclable catalysts for Ullmann and Glaser coupling reactions

The selective capture and efficient reuse of Cu(II) from contaminated seawater requires a multifunctional adsorbent with a high Cu(II) selectivity and magnetic properties to facilitate recycling. Moreover, the cascade application of the recycled adsorbent is important but has not been extensively investigated. Accordingly, in this study, ion-imprinted magnetic adsorbents, particularly, copper ion-imprinted polymers (Fe3O4@mSiO2@CIIP) were prepared using magnetic mesoporous silica microspheres (Fe3O4@mSiO2) as carriers, with organosilicon containing hydroxyl and Schiff bases as the polymer backbone to selectively collect Cu(II) from aqueous media. The adsorption isotherms, kinetics, selectivity, and mechanisms were examined under various adsorption conditions. Fe3O4@mSiO2@CIIP-2 shows high selectivity and fast adsorption kinetics, and the equilibrium adsorption amount of Cu(II) is 263.2 mg/g within 30 min. The pseudo-second-order model and the Langmuir model are supported by the adsorption kinetics and isotherms, respectively. Particularly, the adsorption amount of Fe3O4@mSiO2@CIIP-2 could be reused eight times without substantial loss. Additionally, specific functional monomers bound to Fe3O4@mSiO2@CIIP-2 could both selectively adsorb Cu and serve as functional ligands for catalysts that can heterogeneously catalyze the Ullmann and Glaser coupling reactions after adsorbing Cu(II).