Benching of a real Chinese salt lake environment to achieve lithium ion concentration and osmotic power generation through ionic equilibrium concentration in the forward osmosis process

Abstract

Salt lake brines with high osmotic pressures can be used as natural draw solutions for the Li⁺ concentration process in forward osmosis. However, the problem of low Li⁺ concentrations (a few hundred milligrams per liter) has always prevented forward osmosis from being upscaled from the laboratory. Therefore, in this study, a bench-scale 0.5–1.5 g/L Li⁺ concentration process was carried out, and an equilibrium concentration of approximately 0.2 g/L was reached on the draw solution side. This process was utilized to achieve a low Li⁺ concentration process with a long cycle recovery of 94 % and no attenuation, the average water flux was 28 LMH, and the equipment was successfully operated 30 times in one month. In addition, the focus of this study was on the effect of the operating conditions on the concentration process. The parameters included the temperature, flow rate, and initial feed solution concentration. The temperature varied among 0, 15, and 25 °C since the salt lake area in China is mostly characterized by high altitudes and cold weather. In addition, this study presents a process to recover the osmotic energy of the draw solution during forward osmosis and increase the Li⁺ concentration. Our work lays the foundation for the forward osmosis Li⁺ concentration process in saltwater to move from the laboratory to large-scale production.