Quantum-chemistry guided extractant screening and direct CO2 stripping for recovering lithium from high Na/Li ratio brine

The efficient extraction of lithium from high Na/Li ratio brines remains a critical challenge for sustainable resource utilization. This study develops a trioctyl phosphate (TOP)-dibenzoylmethane (DBM)-kerosene synergistic extraction system guided by density functional theory (DFT) calculations, which reveal complementary electrostatic interactions between the enol oxygen of DBM and the P O group of TOP, facilitating the formation of stable coordination sites for Li + . Under optimized conditions, the system achieves a single-stage lithium extraction efficiency of 97%. Furthermore, an innovative CO 2 -based stripping process eliminates the need for conventional acids by in situ generation of H + via the reaction of CO 2 with H 2 O forms carbonic acid, enabling simultaneous lithium stripping and direct precipitation of Li 2 CO 3 . The integrated process demonstrates high efficiency under ambient conditions, achieving >99% stripping within 4 min and concentrating lithium over 10-fold. The resulting Li 2 CO 3 product exhibits high purity (>99.9%) and well-defined crystallinity, suitable for battery applications. The system maintained excellent stability over ten extraction-washing-stripping cycles with consistent performance. This work offers a green and efficient strategy for lithium recovery from challenging brine sources, combining theoretical molecular design with sustainable process engineering.