Designing an energy-efficient multi-stage selective electrodialysis process based on high-performance materials for lithium extraction

Membrane technologies demonstrate great promise for treating salt lake brines with high Mg/Li mass ratios. However, current coupled membrane processes suffer from many obstacles, including poor membrane separation performance, high energy consumption, noncontinuous processes, large space occupation, and process complexity. Herein, we designed the multi-stage selective electrodialysis (S-ED) process with high-performance monovalent cation exchange membranes (MCEMs) to treat simulated penetration water from a one-stage nanofiltration (NF) process. The mussel-inspired gallic acid/polyethyleneimine assembled membrane (M-GA/PEI) with specific architecture and charge properties demonstrated better separation performance than CSO (a commercial MCEM) during the multi-stage S-ED process. The first-stage and second-stage S-ED processes with high-performance M-GA/PEI showed lower energy consumption (0.029–0.039 kWh·mol−1Li and 0.011–0.014 kWh·mol−1Li, respectively) than those with CSO and other processes with commercial MCEMs for lithium extraction (0.040–3.795 kWh·mol−1Li). This indicated that M-GA/PEI could be deployed as a substitute for commercial MCEMs to reduce the operation costs. This study provides new insights into the design of a multi-stage coupled membrane process (one-stage NF + first-stage S-ED + second-stage S-ED) based on high-performance materials for energy-efficient lithium extraction from salt lake brines towards a sustainable energy-water nexus.