Silane-modified photothermal membrane with enhanced interfacial evaporation for high-efficiency lithium extraction from salt lake brines

Existing solar-driven interfacial evaporation systems for lithium extraction are limited by insufficient evaporation rates and poor Li + /Na + separation. Here, silane-modified acrylic resin (SMA) is introduced to fabricate carbon nanotube/carbon black composite photothermal membranes (CCS) with enhanced interfacial evaporation. Under 1 sun illumination, the optimized CCS-9 membrane achieves an evaporation rate of 1.73 kg·m −2 ·h −1 , exceeding the theoretical evaporation limit of pure water (1.48 kg·m −2 ·h −1 ). This superior performance originates from synergistic heat management and interfacial water regulation: the thermally insulated substrate limits total heat loss to 6.78%, while surface Si O Si groups tailor the hydrogen-bonding network of interfacial water, increase the fraction of intermediate-state water, and reduce the equivalent evaporation enthalpy to 1918.6 J·g −1 . Integrated into a multistage spatial crystallization evaporator, the CCS-9 membrane delivers a LiCl/NaCl separation factor of 38.5 and a LiCl crystallization rate of 8.7 g·m −2 ·h −1 . Pilot-scale outdoor experiments further demonstrate stable evaporation and ion separation under an average solar irradiance of 0.68 kW·m −2 , while preserving the intrinsic separation mechanism. Thermodynamic analysis confirms the phase transition-driven ion partitioning process, and techno-economic evaluation indicates an equivalent energy consumption of 0.086 kWh·g −1 for LiCl recovery, corresponding to an 18.6% reduction in production cost compared with conventional evaporation ponds. This work provides an effective strategy for high-efficiency solar-driven lithium extraction and promotes the practical application of sustainable brine resource recovery.