Topography and structural regulation-induced enhanced recovery of lithium from shale gas produced water via polyethylene glycol functionalized layered double hydroxide

Recovering lithium from wastewater generated during shale gas operations is essential for promoting sustainable resource utilization and safeguarding the environment. This study aimed to develop a lithium adsorbent by modifying lithium-aluminum layered double hydroxide (Li/Al-LDH) using varying concentrations of polyethylene glycol (PEG) of two distinct molecular weights. Remarkably, the application of a 10 % solution of PEG400 at 293 K and a liquid-to-solid ratio of 20 mL/g yielded a substantial enhancement in the lithium adsorption capacity, increasing from 2.50 mg/g to 3.61 mg/g. Characterization studies revealed positive alterations in the physicochemical attributes of Li/Al-LDH after the integration of PEG long chains, particularly in its surface and structural properties. Moreover, DFT calculations demonstrated an increase in Li⁺ binding energy from −1.05 eV to −3.24 eV. The lithium adsorption process in produced water using the modified material reached equilibrium within 15 min through a spontaneous chemical reaction. Its capability to release Li⁺ under neutral conditions offers an environmentally friendly advantage. With a stable cyclic adsorption capacity of around 4.00 mg/g over eight rounds, the material demonstrated remarkable recyclability. This research presents a pioneering advanced lithium adsorbent for the sustainable extraction of lithium from shale gas produced water, thereby advancing the new energy sector.