Abstract: One aspect of the invention relates to customized thin-film composite membranes comprising: a porous support; a selective barrier; and one or more polymeric additives dispersed in the porous support in an amount from at least about 1% and about 50% by weight of the porous support. Another aspect of the invention relates to a method of fabricating a porous support comprising the steps of: preparing a polymer solution comprising a polymer, a polymeric additive, and a first liquid; contacting a surface with the polymer solution; and evaporating the liquid. Another aspect of the invention relates to the use of the thin-film composite membranes disclosed herein in osmotically driven membrane processes.

Abstract: A method of converting thermal energy into mechanical work that uses a semi-permeable membrane to convert osmotic pressure into electrical power. A closed cycle pressure-retarded osmosis (PRO) process known as an osmotic heat engine (OHE) uses a concentrated ammonia-carbon dioxide draw solution to create high osmotic pressures which generate water flux through a semi-permeable membrane against a hydraulic pressure gradient. The depressurization of the increased draw solution volume in a turbine produces electrical power. The process is maintained in steady state operation through the separation of the diluted draw solution into a re-concentrated draw solution and deionized water working fluid, both for reuse in the osmotic heat engine.