Adsorption of gallium from bauxite Bayer liquor using acrylonitrile–Divinylbenzene–Amidoxime resin and deactivation after multiple cycles due to aluminum hydroxide layer

AN-DVB-AO amidoxime resin, widely used for industrial Ga recovery in China, was synthesized. • AN-DVB-AO resin was employed for Ga adsorption from bauxite Bayer liquor in Southwest China. • The failure mechanism of the AN-DVB-AO amidoxime resin in bauxite Bayer liquor was elucidated. In recent years, the rapid development of high-tech industries including semiconductors and new energy has boosted the demand for gallium (Ga), a critical strategic metal. Bayer liquor derived from bauxite processing is the major primary source of Ga. Given increasing resource scarcity and environmental restrictions, developing efficient and eco-friendly Ga recovery technologies has attracted extensive interest. In this study, an acrylonitrile–divinylbenzene (AN–DVB) resin was synthesized via suspension polymerization and further amidoxime (AO)-functionalized with hydroxylamine hydrochloride to obtain AN–DVB–AO resin. Adsorption–desorption behavior and deactivation mechanism of the resin were systematically investigated in real bauxite Bayer liquor. Results demonstrated that the AN–DVB–AO resin exhibited high selectivity for Ga. The maximum adsorption capacity reached 13.1 mg/g after 12 h of amidoximation. After 14 reuse cycles, the Ga adsorption capacity decreased to 6.22 mg/g, representing 52.6% reduction. The primary reason for resin deactivation was the formation of a dense aluminum hydroxide (Al(OH) 3 ) layer after multiple cycles, which blocked active sites and degraded selective Ga adsorption. The aluminum (Al) content on the resin surface increased by 42.7% after 14 cycles, confirming that Al precipitation was the dominant cause of deactivation. The adsorption mechanism was clarified, providing a theoretical basis and technical support for practical Ga recovery from Bayer liquor using AO-modified resin.