This review discusses reverse osmosis (RO) as an energy–efficient approach for concentrating and recovering organic solvents from aqueous solutions, with particular emphasis on ultra–high–pressure RO using organosilica membranes. Although RO has an inherent energy advantage over conventional distillation because it does not involve phase change, its application to high–concentration solutions is limited by increasing osmotic pressure. Process design strategies, including multistage operation, internal recycling, and osmotic–pressure–assisted configurations, can mitigate this limitation by controlling the osmotic pressure difference across the membrane. The second half of this review focuses on the development of organosilica membranes for ultra–high–pressure RO. Organosilica membranes possess tunable subnanometer pore structures, high chemical stability, and sufficient mechanical strength for operation under high–pressure conditions. Atmospheric–pressure plasma treatment enables selective densification of the membrane surface, improving organic–solvent rejection while maintaining high water permeability. Optimization of the multilayer membrane structure further enhances RO performance by reducing transport resistance in the intermediate layer and controlling molecular transport and adsorption in the separation layer. Finally, the advantages of ultra–high–pressure operation are discussed from the perspectives of permeate flux, membrane area, and process configuration. Ultra–high–pressure RO can extend the applicable concentration range of RO and simplify the overall process, providing a promising option for energy–efficient and compact organic solvent recovery.
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