Development and assessment of isatin hydrazone-functionalized/ion-imprinted cellulose adsorbent for gadolinium (III)...

It is of tremendous economic and environmental significance to obtain a powerful adsorbent for the extraction of Gd³⁺ from wastewater. Adsorbents derived from cellulosic materials functionalized with specific chelators show great promise for the removal of heavy metal ions from wastewater. The selectivity of these sorbents for metal ions is, however, still rather poor. Here, we present a technique for trapping Gd³⁺ ions from wastewater by synthesizing Gd³⁺ ion-imprinted polymers based on isatinhydrazone-functionalized cellulose (Gd-ISH-CE). Not only did isatinhydrazone work as a tridentate ligand to directly provide ligand vacancies and build hierarchy pores on Gd-ISH-CE, but it also enabled cross-linking through the epichlorohydrine cross-linker thanks to its very effective NH₂ functionalization. The as-prepared Gd-ISH-CE with ISH functionality shows a high adsorption capacity of 275 mg/g and a rapid equilibration time of 30 min for Gd³⁺ due to its plentiful binding sites and hierarchical pore structure. Furthermore, Gd-ISH-CE shows very selective capture of Gd³⁺ over competing ions. By integrating the benefits of ion-imprinting and chelator functionalization methodologies in an effortless manner, this study presents a practical approach to the development of superior materials for Gd³⁺ recovery.