Enhanced selective extraction of indium and gallium using mesoporous sorbents

Gallium (Ga) and Indium (In) are essential elements in numerous industries, most notably in the rapidly evolving field of optical electronics. Due to their scarcity in natural resources coupled with escalating demand, there is an urgent need to develop sustainable technologies for extracting these elements from secondary sources. This study presents the innovative application of two highly efficient sorbents–mesoporous silica (SBA-15) and ligand-modified mesoporous silica–for the selective extraction of critical elements like indium and gallium from various multi-element solutions. The SBA-15 sorbent showcased remarkable efficiency in adsorbing gallium at a pH of 3, achieving an excellent adsorption capacity of approximately 90 mg/g, which surpasses previously reported values. Conversely, the ligand-modified silica demonstrated significant effectiveness in extracting indium, with an adsorption capacity of ∼ 32 mg/g at pH 3. Furthermore, SBA-15 exhibited remarkable selectivity for gallium in solutions containing Ga, In, and Zn, thereby significantly enhancing the recovery of Ga from In/Ga/ZnO semiconductor target. Additionally, the sorbent displayed exceptional separation efficiency between Ga and Al as well as Ga and In. Similarly, ligand-modified silica showed high selectivity for indium in solutions containing Ga, In, and Zn, achieving excellent separation between In and Zn. Moreover, it effectively extracted indium in binary solutions of In and Sn ions, thereby advancing the recovery of indium from ITO (indium tin oxide) films. After ten cycles of reuse, the sorbents maintained their adsorption capacities, underscoring their potential for industrial applications.