A regenerable ion-imprinted magnetic biocomposite for selective adsorption and detection of Pb²⁺ in aqueous solution

A regenerable ion-imprinted magnetic biocomposite (IIMB) was successfully synthesized for simultaneous removal of Pb²⁺ using Serratia marcescens and carboxymethyl chitosan (CMC) as functional carriers, Pb²⁺ was utilized as the imprinted ion, while Fe₃O₄ served as the magnetic component. The structure and properties of IIMB were characterized by various techniques. The adsorption kinetics, isotherms and thermodynamics were applied to interpret the Pb²⁺ adsorption process on IIMB. The results showed the IIMB possessed prominent uptake ability toward Pb²⁺. The pseudo-second-order kinetic (R² = 0.9989) and Langmuir models (R² = 0.9555) fitted the data well. Adsorption thermodynamics revealed that the adsorption was a spontaneous endothermic reaction. The possible adsorption mechanisms involved physical adsorption, electrostatic attraction and complexing. Moreover, because Pb²⁺ can be specifically and strongly adsorbed on IIMB, a simple method for detection of Pb²⁺ was established by coupling IIMB with flame atomic absorption spectrometry (IIMB-FAAS). The developed IIMB-FAAS assay can sensitively detect Pb²⁺ with a linear range from 5.0 to 500.0 μg/L. The detection limit (LOD) of 0.95 μg/L as well as a quantification limit (LOQ) of 3.20 μg/L were obtained. This work proved that the IIMB could selective and efficient adsorb Pb²⁺, which provided some insights into wastewater treatment, water quality inspection and environmental remediation.