Interfacial polymerization with COF monomers and Sc(OTf) 3 afforded large-area (several cm 2) free-standing films with tunable thickness (2.5 nm to 100 mm). When the films were thick (100 mm), they exhibited X-ray diffraction corresponding to the expected crystalline structure. The films were integrated into the thin-film composite membranes for water nanofiltration, where they showed enhanced rejection of model pollutant Rhodamine WT.

Two-dimensional covalent organic frameworks (COFs) were used to create the first asymmetric, thin-film composite (TFC) nanofiltration (NF) membrane with a COF active layer. NF membrane active layers of polyimine COF were synthesized via the interfacial polymerization (IP) of terephthalaldehyde and tris(4-aminophenyl)benzene monomers on top of a poly(ether sulfone) (PES) ultrafiltration membrane support. Rutherford backscattering spectrometry and Fourier transform infrared spectroscopy analyses confirmed the presence of an imine-linked film with a thickness of ∼10 nm that was formed reproducibly. The rejection efficiencies of the COF NF membrane for a model organic compound, Rhodamine-WT, and a background electrolyte, NaCl, were higher than those of the PES support without the COF film. This enhanced solute rejection is the first successful demonstration of a TFC membrane with a thin COF active layer. However, this work also demonstrates the need for COF NF membranes with smaller active layer pores and alternative support materials. The former should result in greater solute rejection, and the latter is key because the PES used for support in the COF membranes is incompatible with the organic solvents used for the COF IP process.

This paper discusses the environmental effects of incorporating wind energy into the electric power system. We present a detailed emissions analysis based on comprehensive modeling of power system operations with unit commitment and economic dispatch for different wind penetration levels. First, by minimizing cost, the unit commitment model decides which thermal power plants will be utilized based on a wind power forecast, and then, the economic dispatch model dictates the level of production for each unit as a function of the realized wind power generation. Finally, knowing the power production from each power plant, the emissions are calculated. The emissions model incorporates the effects of both cycling and start-ups of thermal power plants in analyzing emissions from an electric power system with increasing levels of wind power. Our results for the power system in the state of Illinois show significant emissions effects from increased cycling and particularly start-ups of thermal power plants. However, we conclude that as the wind power penetration increases, pollutant emissions decrease overall due to the replacement of fossil fuels.

Electrodeionization (EDI) is an electrically driven separations technology that employs ion-exchange membranes and resin particles. Deionization occurs under the influence of an applied electric field, facilitating continuous regeneration of the resins and supplementing ionic conductivity. While EDI is commercially used for ultrapure water production, material innovation is required for improving desalination performance and energy efficiency for treating alternative water supplies. This work reports a new class of ion-exchange resin-wafers (RWs) fabricated with ion-conductive binders that exhibit exceptional ionic conductivities-a 3-5-fold improvement over conventional RWs that contain a non-ionic polyethylene binder. Incorporation into an EDI stack (RW-EDI) resulted in an increased desalination rate and reduced energy expenditure compared to the conventional RWs. The water-splitting phenomenon was also investigated in the RW in an external experimental setup in this work. Overall, this work demonstrates that ohmic resistances can be substantially curtailed with ionomer binder RWs at dilute salt concentrations.