STTR Phase I: COF-based Membrane for Refrigeration

The broader impact of this Small Business Technology Transfer (STTR) Phase I project would come from the successful development of a nano-porous membrane-based filtration technology enabling lower-energy, low-cost, and rapid molecular separations in gas and liquid phases. The proposed technology is to develop new materials for membranes used to separate liquid or gas samples into their components. Although the primary focus of the current project is a new type of refrigeration system, the core technology has a wide range of potential applications including desalination of agricultural and potable water sources, blood dialysis, industrial liquid-liquid separations, CO2 removal from air, and separation of oxygen from air. The intellectual merit of this STTR Phase I projct is to advance a 2-dimensional (2D) molecular sieve, based on a Covalent Organic Framework (COF), to enable a new type of refrigeration system using water and endothermic salts. The closed-cycle refrigeration system requires a nano-porous membrane to regenerate the used coolant into two streams (water and brine) so that a subsequent recombination will again provide a cooling effect. High flux and high rejection of hydrated NH4 cations at low pressures are critical to successful operation. The project will explore the condensation of diamines with dicarbonitriles in COF formation, study how hydrogen substitution in NH groups can optimize rejection of NH4(H2O)4 ions, and investigate how charge works as a rejection mechanism in 2D COFs. Benchmarks include at least 60% rejection of NH4(H2O)4 ions at a flux of 2 L/m2/hr and a cost-effective synthesis of the final COF. The specific goals of the project are to: 1) explore at least 11 variations using a pre-COF formation route, 2) create at least 4 pore variations using a post-COF formation route, and 3) produce and analyze permeate and retentate samples using COF/AAO membranes. The resulting nanoporous COF and its associated rational design process will not only enable the proposed refrigeration application, but will also serve as a guide for future membrane applications. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.