Development and evaluation of thiosalicylic-modified/ion-imprinted chitosan for selective removal of cerium (III) ion

Chitosan was used in this study as the bio-based product for the development of microparticles for the specifically targeted removal of cerium ions (Ce³⁺) by ion-imprinting technology. A thiosalicylic hydrazide-modified chitosan (TSCS) is produced via cyanoacetylation of chitosan, followed by hydrazidine derivatization to finally introduce the thiosalicylate chelating units. Ion-imprinted Ce-TSCS sorbent microparticles were prepared by combining the synthesized TSCS with Ce³⁺, crosslinking the polymeric Ce³⁺/TSCS complex with glutaraldehyde, and releasing the chelated Ce³⁺ using an eluent solution containing a mixture of EDTA and HNO₃. Ce-TSCS had a capacity of 164 ± 1 mg/g and better removal selectivity for Ce³⁺ because it was smart enough to figure out which target ions would fit into the holes made by Ce³⁺ during the imprinting process. The kinetic data were well suited to a pseudo-second-order model, and the isotherms were well described by the Langmuir model, both of which pointed to chemisorption and adsorption through Ce³⁺ chelation. XPS and FTIR analyses demonstrate that the predominant adsorption mechanism is the coordination of Ce³⁺ with the -NH-, -NH₂, and -SH chelating units of the thiosalicylic hydrazidine. These findings provide fresh direction for the development of sorbent materials that can effectively and selectively remove Ce³⁺ from aqueous effluents.