Fast Coadsorption and Selective Separation of Gallium(III) and Germanium(IV) from Aqueous Solutions by 3D Hierarchical Porous Hoya-like α-FeOOH

In order to selectively separate and fast recover gallium(III) and germanium(IV), 3D hierarchical porous hoya-like alpha-FeOOH (3D-alpha-FeOOH) was obtained via a facile one-step synthesis process. Meanwhile, rod-shaped alpha-FeOOH and beta-FeOOH were also prepared for systematically clarifying the excellent adsorption ability of 3D-alpha-FeOOH. The adsorption experiments indicated that the 3D-alpha-FeOOH exhibited fast sorption kinetics, superior adsorption capacities, and preferable affinities toward gallium(III) and germanium(IV) compared to the rod-shaped alpha-FeOOH/beta-FeOOH mainly because of more adsorption sites on the surface of the 3D hierarchical porous structure. Interestingly, the as-prepared 3D-alpha-FeOOH as the adsorbent can coadsorb and selectively adsorb two targets through regulating solution pH. Furthermore, the thermodynamics experiments showed that the Langmuir model could be adequately describe the sorption data for gallium(III) and germanium(IV) and the curves of adsorption kinetics followed the pseudo-second order equation. These results exhibit that 3D-alpha-FeOOH absorbent could be a promising candidate for synchronously recovering and selectively separating gallium(III) and germanium(IV) in aqueous systems and has important application value and prospect in the industrial effluents and acid leaching solution of zinc refinery residues in the future.