Charge transfer-driven enhanced lithium extraction using poly(acrylic) acid-modified layered double hydroxide

This study presents an advanced strategy for developing a novel poly(acrylic) acid-modified layered double hydroxide (PAA@LDH) for enhanced lithium adsorption. The optimal modification conditions include the use of a 2.5 % PAA solution in deionized water, an LDH powder dosage of 90 mL/g, and direct mixing at 333 K. Under these conditions, additional negatively charged functional groups were introduced into the material structure, thereby improving charge transfer, increasing electron cloud density, and lowering equipotential charge, as determined by DFT calculations. Consequently, the modified adsorbent exhibited a substantial rise in lithium adsorption capacity, increasing from 2.08 mg/g to 3.41 mg/g in produced water with low lithium concentration. Adsorption kinetics were rapid, reaching equilibrium within 40 min, and the adsorption behavior conformed to the Langmuir isotherm model. Besides, the adsorbent exhibited excellent selectivity for Li⁺ ions and maintained its performance at approximately 3.40 mg/g over seven cycles when regenerated under neutral conditions. The findings establish a robust framework for designing innovative adsorbent systems for lithium recovery from aqueous sources like produced water.