Selective leaching of indium from spent LCD screens by siderophore desferrioxamine E

Given the criticality of indium (In) in high-tech applications, spent LCD screens can represent a viable secondary In resource. In this work, an innovative and alternative technology to selectively leach In from spent LCD screens using a microbial chelating agent, desferrioxamine E (DFOE), was developed. Indium was concentrated from spent LCD screens by implementing an adapted pre-treatment procedure, allowing the isolation of an indium-rich glassy fraction. During leaching, the competition between aluminum (Al) and In for complexation with DFOE leads to the precipitation of In(OH)3 at low DFOE concentration (12-240 µM). After adjusting the optimal conditions (fraction size: 0-36 μM, pH: 5.5, S/L ratio: 1 g/L, 25 °C), the In leaching yield reached 32%, ten times higher than Al over 90 days with 5 mM DFOE. Thus, achieving high In recoveries is possible through i) prolonged leaching durations, ii) selective leaching, and iii) minimizing Al interference. This is the first attempt to selectively leach In using a selected siderophore from end-of-life products with high concentrations of non-targeted elements (i.e. Al, Si, and Ca). This study demonstrates the potential of generating indium-rich leachates, which can be subsequently processed through the GaLIophore technology for In refining. Improper disposal of e-waste can result in the release of hazardous materials, causing environmental pollution. Waste LCDs, containing significant indium concentration, provide a secondary resource for indium recovery, thereby enhancing e-waste utilization and reducing its environmental footprint. Indium recovery is essential for resource sustainability, yet existing recycling technologies lack comprehensive solutions. Our innovative approach, employing the siderophore DFOE, facilitates the selective leaching of indium even in the presence of highly concentrated non-target elements. This method integrates hydrometallurgy and biohydrometallurgy, presenting an eco-friendly and efficient strategy. Moreover, the used DFOE can be recycled to maintain the integrity of the recycling chain.