Title Synergistic sorption of gallium(III) and scandium(III) ions by the interpolymer system of poly(acrylic acid)/poly(4-vinylpyr-idine) hydrogels: kinetics, selectivity, and mechanism
Authors Totkhuskyzy, Bakytgul ; Jumadilov, Talkybek ; Khimersen, Khuangul ; Akhmetova, Arailym ; Haponiuk, Józef ; Gražulevičius, Juozas Vidas
DOI 10.3390/molecules31183324
Full Text Download
Is Part of Molecules.. Basel : MDPI. 2026, vol. 31, iss. 18, art. no. 3324, p. 1-36.. ISSN 1420-3049
Keywords [eng] Langmuir isotherm ; gallium(III) sorption ; hydrometallurgy ; intergel hydrogels ; poly(4-vinylpyridine) ; poly(acrylic acid) ; scandium(III) sorption ; selective separation
Abstract [eng] Selective recovery of critical metals such as gallium and scandium from dilute, multicomponent process streams remains challenging due to their low concentrations and complex matrices. Here we investigate a remotely interacting intergel system based on crosslinked poly(acrylic acid) (hPAA) and poly(4-vinylpyridine) (hP4VP) hydrogels across seven mass ratios (6:0-0:6) for sorption of Ga(III) and Sc(III) from binary sulfate solutions. Inductively coupled plasma optical emission spectroscopy shows that mutual activation of the weak polyacid/polybase pair markedly enhances metal uptake, with maximum sorption degrees of 73.17% for Ga(III) at hPAA:hP4VP = 3:3 and 56.00% for Sc(III) at 2:4, corresponding to distribution coefficients up to 2726.7 mL g-1 and Ga/Sc selectivity factors β up to 6.41. Sorption is well described by Langmuir-type isotherms, and desorption with 2 wt.% HNO3 reveals an inverse sorption-release relationship, indicating stronger binding at compositions of maximal mutual activation. FTIR spectroscopy evidences inner-sphere complexation through bidentate carboxylate coordination in hPAA and M←N dative bonding in hP4VP, while TGA/DSC shows that metal-loaded hydrogels retain their structural integrity up to approximately 320-340 °C, with the onset of significant decomposition occurring at ~350 °C for hP4VP-containing samples. The composition-dependent magnitude of Ga(III)-over-Sc(III) preferential uptake-with selectivity coefficients β = Kd(Ga)/Kd(Sc) remaining greater than 1 across all seven compositions studied-is rationalized using Hard-Soft Acid-Base considerations and demonstrates that hPAA:hP4VP intergels constitute a composition-tunable platform for enhancing Ga(III) recovery and partial Ga/Sc separation from simplified sulfate media, motivating future validation in real hydrometallurgical liquors and in the presence of competing multivalent cations.
Published Basel : MDPI
Type Journal article
Language English
Publication date 2026
CC license CC license description