Insight into the gallium selectivity mechanism of in-suit ion-imprinted material in multi-ion systems

In order to confirm the selectivity and mechanism of self-synthesized imprinted materials (Ga-IIP-PP) for Ga ions in mixed solutions, the adsorption experiments of bimetallic and polymetallic systems, material characterization (SEM-EDS, XPS) and Density Functional Theory (DFT) calculations were applied to examine and reveal the selective adsorption performance and mechanism of Ga-IP-PP for Ga ions. The results showed that Ga-IIP-PP exhibited excellent selectivity for Ga ions in both Ga/Al binary system and multi-ion systems, and the adsorption efficiency of Ga ions is more than 70 %. XPS analysis indicated that the phenolic hydroxyl groups in the imprinted cavity were the main adsorption sites, and the superior selectivity of the imprinted material for Ga ions derived from the stronger complexation of the imprinted sites to Ga(III), stronger electrostatic attraction of Ga-IIP-PP to Ga(III) and the high matching degree of the imprinted cavity to Ga(III). In addition, the binding energy (E ad ), Molecular Electrostatic Potential (MEP), total electron density, Mulliken charge and Frontier Molecular Orbitals (FMOs) analysis of the Ga-IIP-PP + Ga(III)/Al(III) system pointed to more electron exchange, larger absolute value of binding energy, higher electron cloud overlap, and larger orbital energy gap (E gap ) between Ga-IIP-PP and Ga ions, which confirmed a stronger adsorption affinity of Ga-IIP-PP for Ga ions than Al ions.