Numerical simulation of Lithium extraction from salt Lake brines through force environment modulation in microfluidic channels with ion concentration polarization

Force-environment-modulated microfluidic devices possess significant potential for the efficient lithium extraction from salt-lake brines. This paper proposes a novel force-environment-modulated system for the simultaneous Li⁺ concentration and Mg²⁺ removal from high Mg²⁺/Li⁺ ratio (MLR) brines. In this system, multiple parallel barriers are positioned within a microchannel to regulate the flow of fluids. The differentiated horizontal fluid flow velocities implement a localized region of force balance for Li⁺ exclusively, enabling Li⁺ to be collected at the upward outlet while continuously expelling other ions. In addition, a vertical barrier in front of the balance region will increase Li⁺ enrichment and decrease it on the opposing side, thus further enhancing the concentration of Li⁺ and the removal of Mg²⁺ to a greater extent. The results obtained through two-dimensional simulation using a diluted model brine demonstrate that this system has the capability to concentrate Li⁺ by 4.5 times and achieve an 89% removal of Mg²⁺, where the MLR decrease to 3.45, and the separation factor reaches 6.17. The modulation of force environments for differently charged particles provides a new approach to achieve their simultaneous concentration and separation.