In-suit ion-imprinted bio-sorbent with superior adsorption performance for gallium(III) capture

A superior persimmon peel-based imprinted material (Ga-IIP-PP-OP) was obtained by optimizing the preparation conditions such as cross-linking agent dosage, type of solvent, addition amount of template ions, polymerization temperature and polymerization time. The internal and external morphology and structure of Ga-IIP-PP-OP were examined by SEM, TEM and BET, and the adsorption mechanism of gallium ions on Ga-IIP-PP-OP was analyzed by FTIR, XPS and DFT calculation. The results showed that under the optimum conditions (methanol-water (3:7) as solvent, addition amount of template ions = 1.42 μmol, cross-linking agent dosage = 0.351 mg/g pp powder, polymerization temperature = 80 °C, polymerization time = 6 h), the adsorption capacity of Ga-IIP-PP-OP can reach 352.64 mg/g under pH = 3, which is significantly higher than other reported gallium adsorbents. Moreover, Ga-IIP-PP-OP with abundant porous structure and dense cross-linking network exhibited a strong affinity for Ga (III) even in binary systems with similar competitive ions. The remarkable adsorption capacity of Ga-IIP-PP-OP is attributed to electrostatic attraction of phenoxy negative ions to Ga (III) and chelation of phenolic hydroxyl and ester groups with Ga (III), with an ester group in the tannin structural unit and adjacent hydroxyl groups on another structural unit as the most stable adsorption site. These results revealed that the optimization of the synthesis conditions allowed the imprinted material to demonstrate greater potential for selective adsorption and efficient recovery of Ga (III).