A cartridge comprising layers of adsorbent sheet is described. The cartridge includes an indicator that characterizes the consumption state of the adsorbent within the cartridge. The indicator is applied in a way such that discrete areas of indicator are visible. These discontinuous areas of indicator may be applied to the outside surface of the cartridge. Alternatively, the discontinuous areas may be formed by cutting windows in the outermost layer of the cartridge and either coating indicator on the layer beneath the window, placing an indicator layer between the window and the layer beneath it or filling the window with an indicating plug of material so that the indicator is visible from the outside of the cartridge. The indicator layer and indicator plug embodiments allow the use of any indicator with any adsorbent.

An air revitalization system may include a humidity control device configured to remove water vapor from air within a pressurized enclosed volume. The system may further include an inlet duct configured to transport the air from the pressurized enclosed volume to the humidity control device. The system may also include an outlet duct configured to transport the air from the humidity control device to the pressurized enclosed volume. The system may include a sublimator configured to cool the air within the pressurized enclosed volume while generating additional water vapor. The system may further include a vacuum vent duct configured to transport the water vapor from the humidity control device and the additional water vapor from the sublimator to an exterior of the pressurized enclosed volume.

Separating oxygen from a gas includes contacting an oxygen-selective sorbent with a gas stream, adsorbing oxygen in the gas stream with the sorbent, heating the sorbent to greater than 400° C., and desorbing a majority of the oxygen. The sorbent is selective for oxygen, and adsorbing occurs at a temperature between 275-325° C. An oxygen separation system includes a sorption bed, a heater configured to heat the sorption bed, an oxygen analyzer, a first conduit configured provide an input gas to the sorption bed, a second conduit configured to provide processed input gas from the sorption bed to the oxygen analyzer, a third conduit configured to provide a purge gas to the sorption bed, and a fourth conduit configured to provide processed purge gas to the oxygen analyzer. The first and third conduits are configured to flow the input gas and the purge gas flow in opposite directions through the sorption bed.

An adsorbent composition for capturing pollutants includes a porous composition that includes a plurality of ferric oxyhydroxide particles and an additional component in the porous composition. The additional component includes one of copper chloride (CuCl.sub.2), zinc chloride (ZnCl.sub.2), polyvinylpolypyrrolidone, silicon carbide, silicon dioxide, activated carbon or other carbonaceous material, and a combination thereof.

Systems and methods for heat exchange during gas adsorption and desorption cycling, one method including removing heat from an adsorbent material during gas adsorption to the adsorbent material; storing the removed heat for later use during desorption of gas from the adsorbent material; heating the adsorbent material during desorption of gas from the adsorbent material using at least a portion of the removed heat; and recycling heat during the step of heating to prepare a working fluid for the step of removing heat via temperature reduction of the working fluid.

A system for capturing CO.sub.2 gas comprising: a gaseous feed stream having an initial concentration of the CO.sub.2 gas; wherein the gaseous feed stream is provided to a first reactor as a gaseous reaction stream; the first reactor comprising a sorbent composition and the gaseous reaction stream flowing therein, the gaseous reaction stream being in contact with the sorbent composition; and a first gaseous output stream having a concentration of CO.sub.2 being less than the initial concentration of CO.sub.2; wherein: the gaseous reaction stream comprises the CO.sub.2 gas and is characterized by a relative humidity of at least 5%; the sorbent composition comprises a metal carbonate material that reacts with the CO.sub.2 gas of the gaseous reaction stream thereby reducing CO.sub.2 gas concentration; and the first reactor comprises 35 wt. % or less of liquid water by weight of sorbent and liquid water.

A carbon dioxide adsorbent may include a double salt having a first metal salt and a second metal salt. The first metal salt may include a first metal selected from Ca, Sr, and Ba. The second metal salt may include a second metal selected from Li, Na, K, Rb, and Cs. The present disclosure also discloses a process for preparing the carbon dioxide adsorbent and a method of separating carbon dioxide using the same.

The present invention provides processes for filtering undesired chemicals in streams of contaminated air for supply to confined areas. The processes provide (1) contacting air with a filter comprising by volume from about 5% to about 95% impregnated zirconium hydroxide, from about 5% to about 95% activated impregnated carbon, and optionally, up to about 50% ammonia removal material; and (2) supplying the contacted air to a confined area.

Dry processes, apparatus, compositions and systems are provided for reducing emissions of sulfur oxides, and sulfur dioxide in particular, and/or HCl and/or Hg in a process employing a combination of a lime-based sorbent, in particular hydrated lime and/or dolomitic hydrated lime, and a sorbent doping agent administered to achieve coverage of a three-dimensional cross section of a passage carrying SO.sub.x and/or HCl and/or Hg-containing gases with a short but effective residence time at a temperature effective to provide significant sulfur dioxide and/or HCl and/or Hg reductions with high rates of reaction and sorbent utilization. The once-through, dry process can advantageously introduce the sorbent and sorbent doping agent dry or preferably as a slurry to enable uniform treatment. Preferred sorbent doping agents include water-soluble or water-dispersible copper and/or iron compositions which can be heated to an active form in situ by the flue gases being treated.

Compositions that can be used to adsorb low concentration, of unwanted or target substances from a dynamic fluid stream or from an enclosed static vapor phase. Such adsorbency can be obtained with thermoplastic materials used in the form of bulk polymer or a film, fiber, web, woven fabric, non-woven fabric, sheet, packaging and other such structures including or surrounding the enclosed volume. The concentration should be reduced to non-offensive sensed limits or a limit that does not produce a biological response.