Preparation of graphene-based surface ion-imprinted adsorbent for Ga(Ⅲ) selective extraction from acid leaching of fly ash

Abstract

To meet the requirements of Ga(Ⅲ) selective adsorption from acid leaching of fly ash, a grapheme-based Ga(Ⅲ) imprinted polymer is developed by combining adsorption method with surface ion imprinting technology. The obtained Ga(Ⅲ) imprinted polymer can effectively adsorb Ga(Ⅲ) with a maximum adsorption capacity of 221.56 mg g−1 at an initial concentration of 200 mg/L within 240 min. The pseudo-second order model (R2 = 0.9882) and Langmuir isotherm (R2 = 0.9628) fitted the Ga(Ⅲ) adsorption data well. In addition, the imprinted adsorbent exhibits significant selectivity towards Ga(Ⅲ) in a simulated acid leaching of fly ash. The selectivity coefficients of Ga(Ⅲ) with respect to Al(Ⅲ), Fe(Ⅲ), Mg(Ⅱ), and Ca(Ⅱ) are 10.09, 3.36, 18.50, and 55.50, respectively. The synthesized imprinted adsorbent exhibits excellent regeneration ability, maintaining 85.71% of its initial adsorption capacity after 5 adsorption-regeneration cycles. The binding energy of Ga(Ⅲ) to functional monomers is calculated as −16.79 kJ mol−1, which confirms that Ga(Ⅲ) can be effectively adsorbed. The theoretical simulated calculation results are basically in consistence with the experimental results, which confirms the selective adsorption mechanism of Ga(Ⅲ). Therefore, it provides a new idea for the extraction of Ga(Ⅲ) from acidic environments.