Amino-functionalized chitosan-polyethyleneimine porous material for iodide removal: Adsorption performance, synergistic mechanism and application.

A lightweight, compressible amino-functionalized porous adsorbent, prepared through glutaraldehyde (GA)-mediated crosslinking of chitosan (CS) and polyethyleneimine (PEI), was denoted as CS-PEI-GA for efficient iodide (I-) removal. The structural and physicochemical characteristics were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). CS-PEI-GA exhibited a maximum adsorption capacity of 1.12 ± 0.01 mmol g-1. The adsorption kinetics and equilibrium isotherms were best described by the pseudo-second-order and Freundlich models, respectively. Thermodynamic analysis, together with FT-IR and X-ray photoelectron spectroscopy (XPS) results, suggested that iodide adsorption involved electrostatic attraction between protonated amino groups and iodide ions, with additional contributions from hydrogen bonding. Application to concentrated seaweed juices achieved 21.52 ± 0.74%-45.77 ± 2.73% iodide removal, with minimal impact on color. These findings highlight the potential of the CS-PEI-GA porous material as an efficient adsorbent for iodide removal.