Ion-imprinted chelating resin for targeted adsorption of lanthanum ions: synthesis, characterization, and application

BACKGROUND

Lanthanum ions (La³⁺) are of great importance in many applications, so development of effective sorbents for selective recovery of La³⁺ is urgently required. In this work, an ion-imprinted polymeric sorbent of La-RSPY with secondary amine, phenolic, and pyridyl groups was synthesized through a Schiff base reaction between 4-aminoresorcinol and pyridine-2-carboxaldehyde, followed by reduction, La³⁺ complexation, and base-catalyzed polymerization with resorcinol/formaldehyde.

RESULTS

La-RSPY showed impressive selectivity to La³⁺ from competitive ions like Gd³⁺, Ru³⁺, Pr³⁺, Eu³⁺, Nd³⁺, Cd²⁺, Zn²⁺, and Cu²⁺ in mixed-ion systems with an adsorption capacity of 200 ± 1 mg g⁻¹. Its adsorption behavior was successfully modeled using the Sips isotherm, while the pseudo-second-order kinetics further confirmed the efficiency of the process. Spectroscopic analysis using NMR, FTIR, and SEM also confirmed that the integrity of the sorbent was unaffected. Such better performance is due to the CN, NH, and OH groups that give rise to stable La³⁺ complexes and imprinted spatial configurations tailored for La³⁺ binding.

CONCLUSION

La-RSPY has great promise for applications in analytical chemistry, food safety, wastewater treatment, and environmental remediation. Scaling up synthesis, optimizing processes, and collaboration with industries specializing in rare earth recovery or water treatment would increase its practical deployment and widen its commercial circle. © 2025 Society of Chemical Industry (SCI).