Efficient osmotic energy recovery from organic wastewater using a two-dimensional porphyrin-based metal-organic frameworks membrane

Harvesting osmotic energy plays a crucial role in addressing the global depletion crisis of fossil energy and achieving a structural transformation in energy. However, current research predominantly focuses on osmotic energy stored in natural seawater, with relatively little attention given to other saline sources such as industrial wastewater. In this study, a two-dimensional Cu-TCPP metal-organic framework (MOFs) nanosheet was prepared, and a nanofluidic membrane with high osmotic energy recovery efficiency from industrial organic saline wastewater was constructed. In a LiCl methanol solution system with a 100-fold salinity gradient, the Cu-TCPP membrane achieved a stable power density of 4.87 W/m2. Simulation analysis suggests that the membrane's efficient ion-selective transport in the organic system can be primarily attributed to abundant diffusion pathways, including intrinsic pores in the nanosheet and two-dimensional nanochannels between adjacent nanosheets. Furthermore, the physicochemical properties of the nanochannel membrane and the type of solvent and ions significantly impact osmotic energy recovery efficiency in organic solvents. This work provides a novel approach to the treatment and resource utilization of industrial organic wastewater in the chemical and pharmaceutical industries.