Using laser-induced fluorescence, measurements have been made of metastable argon-ion, Ar + * (3d 4 F 7/2 ), velocity distributions on the major axis of an axisymmetric magnetic-mirror device whose plasma is sustained by helicon wave absorption. Within the mirror, these ions have sub-eV temperature and, at most, a subthermal axial drift. In the region outside the mirror coils, conditions are found where these ions have a field-parallel velocity above the acoustic speed, to an axial energy of ∼ 30 eV, while the field-parallel ion temperature remains low. The supersonic Ar + * (3d 4 F 7/2 ) are accelerated to one-third of their final energy within a short region in the plasma column, ≤ 1 cm, and continue to accelerate over the next 5 cm. Neutralgas density strongly affects the supersonic Ar + * (3d 4 F 7/2 ) density.

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We develop a nonlinear optimization model to identify minimum cost designs for osmotically assisted reverse osmosis (OARO), a multi-staged membrane-based process for desalinating high salinity brines. The optimization model enables comprehensive evaluation of a complex process configuration and operational decision space that includes nonlinear process performance and implicit relationships between membrane stages, saline sweep cycles, and make-up, purge, and recycle streams. The objective function minimizes cost, rather than energy or capital expenditures, to accurately account for the tradeoffs in capital and operational expenses inherent in multi-staged membrane processes. Generally, we find that cost-optimal OARO processes minimize the number of stages, eliminate the use of saline make-up streams, purge from the first sweep cycle, and successively decrease stage membrane area and sweep flowrates. The optimal OARO configuration for treating feed salinities of 50-125 g/L total dissolved solids to a water recovery of 30-70% results in process costs less than or equal to $6 per m3 of product water. Sensitivity analysis suggests that future research to minimize OARO costs should focus on minimizing the membrane structural parameter while maximizing the membrane burst pressure and reducing the membrane unit cost.

The proton-coupled electron transfer (PCET) reaction of a quinone has been used to create a pH gradient capable of the active pumping of CO2 through a liquid membrane. The quinone redox couples, hydroquinone/benzoquinone and 2,6-dimethylbenzoquinone/2,6-dimethylhydroquinone, have been investigated in the proton transfer mechanisms associated with electron transfer in sodium bicarbonate solutions. These same conditions have then been applied to an active liquid membrane for proton pumping across a membrane electrode assembly under potential bias, acting as an active membrane for CO2 separation. Qualitative results are reported toward the development of an active redox membrane for CO2 separation from flue gas.