Dual-modification engineering of Al-based Li adsorbents for enhanced sulfate resistance and anion-selective lithium recovery

Microemulsion-enabled interfacial design with graphene oxide incorporation and polycarboxylate intercalation. • Sulfate-tolerant design enables lithium recovery from natural sulfate-rich salt-lake brines. • Integrated experiments and DFT/MDsimulations reveal cooperative Li + selectivity. • Column operation demonstrates stable, environmentally benign brine treatment. Adsorption-based lithium extraction provides a convenient, efficient, and environmentally friendly route for recovering lithium from liquid resources. Among existing materials, aluminum-based adsorbents are the only systems that have achieved industrial-scale deployment; however, they still suffer from insufficient lithium uptake and structural deactivation during long-term dynamic cycles in sulfate-type salt-lake brines. To address these limitations, a dual-modified lithium–aluminum layered double hydroxide (PGLH) was synthesized via microemulsion-assisted coprecipitation.Structural characterization and computational analyses reveal that the intercalation of polycarboxylates within the interlayer galleries, coupled with graphene oxide (GO) surface modification, synergistically reinforces the layered framework and enhances Li + selectivity. In gradient-concentration real sulfate-type brines, PGLH delivers a lithium adsorption capacity of 17.8 mg·g −1 . Sulfate resistance experiments and molecular dynamics simulations demonstrated a 260% increase in lithium uptake compared to unmodified adsorbents, along with 96.1% capacity retention after fifty cycles, which is attributed to steric hindrance and electrostatic repulsion that effectively suppress sulfate intercalation. Continuous-flow column tests further verified the material's durability, achieving more than tenfold Li + enrichment and reducing the Mg/Li ratio from 2938:1 to 10:1. These findings provide mechanistic insights and design guidelines for developing robust, selective Al-based lithium adsorbents suitable for sulfate-rich brines. A polycarboxylate and graphene oxide co-modified layered alumina adsorbent (PGLH) was synthesized via a microemulsion-assisted method. Interlayer engineering and surface modification synergistically enhanced Li + selectivity in authentic sulfate-rich brines. Structural characterization, adsorption tests, and DFT/MD simulations demonstrate that interfacial modification stabilizes the layered structure and tunes competitive anion sorption, providing mechanistic insight into selective lithium recovery from complex multi-ion environments. Download: Download high-res image (183KB) Download: Download full-size image