Primary, secondary (1°,2°) alkylethylenediamine- and alkylpropylenediamine-appended variants of metal-organic framework are provided for CO.sub.2 capture applications. Increasing the size of the alkyl group on the secondary amine enhances the stability to diamine volatilization from the metal sites. Two-step adsorption/desorption profiles are overcome by minimzing steric interactions between adjacent ammonium carbamate chains. For instance, the isoreticularly expanded framework Mg.sub.2(dotpdc) (dotpdc.sup.4−=4,4″-dioxido-[1,1′:4′,1″-terphenyl]-3,3″-dicarboxylate), yields diamine-appended adsorbents displaying a single CO.sub.2 adsorption step. Further, use of the isomeric framework Mg-IRMOF-74-II or Mg.sub.2(pc-dobpdc) (pc-dobpdc.sup.4−=3,3-dioxidobiphenyl-4,4-dicarboxylate, pc=para-carboxylate) also leads to a single CO.sub.2 adsorption step with bulky diamines. By relieving steric interactions between adjacent ammonium carbamate chains, these frameworks enable step-shaped CO.sub.2 adsorption, decreased water co-adsorption, and increased stability to diamine loss. Variants of Mg.sub.2(dotpdc) and Mg.sub.2(pc-dobpdc) functionalized with large diamines such as N-(n-heptyl)ethylenediamine have utility as adsorbents for carbon capture applications.

The present disclosure relates to a system and method for treating wastewater, the method comprising the steps of: providing a vessel for receiving wastewater and a gas, wherein the gas comprises one or more constituent gas components; directing the wastewater and a first gas component of the gas to the vessel; reducing the temperature of the contents of the vessel from a first temperature to a second temperature to facilitate the formation of clathrate hydrates comprising the wastewater and the first gas component; increasing the temperature of the contents of the vessel with respect to the second temperature to facilitate melting of the clathrate hydrates; and removing clean water and/or the first gas component from the vessel.

Separation of a gas mixture comprising first and second gases may be improved using three stages of gas separation membrane modules that includes the additional techniques of cooling the feed gas stream that is fed to the feed stage and using a portion of the permeate stage retentate as a sweep gas on the permeate stage.

Separation of a gas mixture comprising first and second gases may be improved using four stages of gas separation membrane modules that includes the additional techniques of cooling the feed gas stream that is fed to the first (feed) stage and using a portion of the fourth (second permeate) stage retentate as a sweep gas on the permeate stage.

Membranes, methods of making the membranes, and methods of using the membranes are described herein. The membranes can comprise a gas permeable support layer, an inorganic layer disposed on the support, the inorganic layer comprising a plurality of discreet nanoparticles having an average particle size of less than 1 micron, and a selective polymer layer disposed on the inorganic layer, the selective polymer layer comprising a selective polymer having a CO.sub.2:N.sub.2 selectivity of at least 10 at 57° C. In some embodiments, the membrane can be selectively permeable to an acidic gas. The membranes can be used, for example, to separate gaseous mixtures, such as flue gas.

A low cost, high selectivity asymmetric polyimide/polyethersulfone (PES) blend hollow fiber membrane, a method of making the membrane and its use for a variety of liquid, gas, and vapor separations such as deep desulfurization of gasoline and diesel fuels, ethanol/water separations, pervaporation dehydration of aqueous/organic mixtures, CO.sub.2/CH.sub.4, CO.sub.2/N.sub.2, H.sub.2/CH.sub.4, He/CH.sub.4, O.sub.2/N.sub.2, H.sub.2S/CH.sub.4, olefin/paraffin, iso/normal paraffins separations, and other light gas mixture separations. The polyimide/PES blend hollow fiber membrane is fabricated from a blend of a polyimide polymer and PES and showed surprisingly unique gas separation property with higher selectivities than either the polyimide hollow fiber membrane without PES polymer or the PES hollow fiber membrane without PES polymer for gas separations such as for H.sub.2/CH.sub.4, He/CH.sub.4, H.sub.2S/CH.sub.4, CO.sub.2/CH.sub.4 separations.

The present invention relates to a micro-bubble pump apparatus for a water treatment, and the micro-bubble pump apparatus for a water treatment comprises: a motor for generating rotatory power; and a micro-bubble pump connected to the motor and for mixing a feed liquid which flows into one side thereof and a feed gas which is injected into the other side thereof.

A biogas plant includes a fermenter, a biogas processing unit and a thermal engine. The biogas processing unit includes a gas separation unit and a compression unit for the separation of raw biogas from the fermenter into two gas streams, whereby the first gas stream includes a product gas that is enriched in biomethane with respect to the composition of the raw biogas and the second gas stream includes a residual gas that is enriched with carbon dioxide with respect to the composition of the raw biogas and has a biomethane concentration of less than 20%. The thermal engine produces energy that is used for operation of the compression unit.

A thermo-electrochemical reactive capture apparatus includes an anode and a cathode, wherein the anode includes a first catalyst, wherein the cathode includes a second catalyst, a porous ceramic support positioned between the anode and the cathode, an electrolyte mixture in pores of the ceramic support, and a steam flow system on an outer side of the cathode. The outer side of the cathode is opposite an inner side of the cathode and the inner side of the cathode is adjacent to the ceramic support. In addition, the electrolyte mixture is configured to be molten at a temperature below about 600° C.

At least some VOCs are removed from a feed gas in an adsorption unit comprising at least three adsorbers following a pressure cycle with a phase shift, wherein the feed gas comprises at least methane, carbon dioxide and volatile organic compounds (VOCs). The VOC depleted gas is fed to at least one membrane separation to produce a carbon dioxide-enriched permeate and a methane-enriched retentate. The flow of the feed gas stream is adjusted based upon one or both of a pressure or methane concentration of the gas stream entering the membrane separation unit and/or a pressure in the adsorption unit.