Thermo-osmotic membrane distillation-crystallization for enhanced dehydration of lithium brines and sustainable SWRO brine management

Lithium (Li) is a strategically critical material for the global energy transition, with nearly 50 % of global production derived from hypersaline brines. Conventional pre-concentration via evaporation ponds is time-consuming, leads to substantial water loss, and raises environmental concerns. Simultaneously, the global expansion of seawater reverse osmosis (SWRO) desalination presents growing challenges related to the disposal of hypersaline brines that threaten marine ecosystems. This study introduces Thermo-Osmotic Membrane Distillation-Crystallization (T-OMD-Cr) as an integrated process to enhance Li recovery and promote sustainable brine management. Using synthetic Li-rich solutions, T-OMD-Cr utilized SWRO brine as a stripping agent, achieving a water flux of 4.3 kg·m −2 ·h −1 at 60 °C, 27 % higher than conventional Membrane Distillation. This approach enabled selective halite crystallization, representing the first step of salt fractionation from a solution mimicking the composition of salars from the Atacama Desert (Chile). Crystallization kinetics indicated that the elevated supersaturation induced by the SWRO brine significantly enhanced nucleation, yielding smaller and more uniform crystals. Thermodynamic modeling using PHREEQC accurately predicted NaCl precipitation, validating the experimental results. These findings highlight the potential of T-OMD-Cr to intensify Li extraction, reduce brine discharge, and contribute to more circular, environmentally responsible desalination–mining systems. • SWRO brine used in T-OMD-Cr enhances water flux by 27 % over distilled water. • High flux raises supersaturation, boosting crystal nucleation and slowing growth. • Phreeqc model predicts salt precipitation, confirming NaCl fractionation. • T-OMD-Cr produces high-quality halite with a purity of 80 % from Li-brine. • SWRO brine dilution to seawater salinity mitigates environmental disposal risks.