Pb(II)-imprinted chitosan beads to enhance the adsorption property and selectivity: characterization, kinetics, and thermodynamics

An effective and selective ion-imprinted biosorbent was prepared from chitosan, using Pb(II) ions as templates and ethylene glycol diglycidyl ether as the crosslinker. The resultant Pb(II)-imprinted chitosan beads (Pb-ICB) were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, and thermogravimetric analysis. The adsorption property and selectivity of Pb-ICB were evaluated for the adsorption of Pb(II). The results showed that Pb-ICB had more cavities, but lower crystallinity and thermal stability than non-imprinted chitosan beads (NICB). Much higher adsorption capacity in the single metal system and better selectivity in the binary metal system for the adsorption Pb(II) were achieved with Pb-ICB than NICB. The maximum adsorption capacity of Pb(II) on Pb-ICB reached 177.62 mg/g. The kinetic and isothermal analyzes showed that the adsorption process of Pb(II) onto Pb-ICB well-fitted pseudo-second-order kinetic and Langmuir isotherm models. The thermodynamic analysis revealed that the adsorption of Pb(II) onto Pb-ICB was a spontaneous and endothermic process. Furthermore, Pb-ICB showed good reusability within five cycles of adsorption–desorption.