A method of scrubbing a gas, such as flue gas or exhaust gas, comprising carbon dioxide to deplete the gas of carbon dioxide (CO.sub.2), the method comprising the steps of: scrubbing the gas in a scrubber (210) with a first alkaline, aqueous scrubbing liquid to dissolve carbon dioxide (CO.sub.2) as hydrogen carbonate (HCO.sub.3.sup.−) and/or as carbonate (CO.sub.3.sup.2−) in the first alkaline, aqueous scrubbing liquid, thereby providing a first spent aqueous scrubbing liquid comprising hydrogen carbonate (HCO.sub.3.sup.−) and/or carbonate (CO.sub.3.sup.2−), the first spent aqueous scrubbing liquid having a pH from about 7 to about 9; feeding the first spent aqueous scrubbing liquid to an anode chamber of an electrolytic cell (310) comprising the anode chamber (313) and a cathode chamber (312) separated by a membrane (311); regenerating the first spent aqueous scrubbing liquid in the electrolytic cell (310) by electrolysis, the electrolysis increasing the pH of the first spent aqueous scrubbing liquid in the cathode chamber (312), the electrolysis further depleting the first spent aqueous scrubbing liquid of hydrogen carbonate (HCO.sub.3.sup.−) and of carbonate (CO.sub.3.sup.2−) in the anode chamber (313) by decreasing the pH, the regeneration further comprising generating gaseous hydrogen in the cathode chamber (312) and a gaseous mixture of oxygen and carbon dioxide (CO.sub.2) in the anode chamber (313) by electrolysis; and withdrawing regenerated alkaline, aqueous scrubbing liquid from the cathode chamber (312) and re-circulating it to the scrubber (210); wherein: the gaseous hydrogen is withdrawn from the cathode chamber (312); and the gaseous mixture of oxygen and carbon dioxide is withdrawn from the anode chamber (313).

A process for removing hydrogen sulfide from a sour gas stream is presented. The method oxidizes hydrogen sulfide to sulfuric acid by reducing aqueous bromine to hydrobromic acid in solution. The aqueous bromine solution does not react with hydrocarbon components common to natural gas including methane and ethane. This allows the process to both sweeten sour gas and convert its hydrogen sulfide content to sulfuric acid in a single step. In the present process, sulfuric acid is concentrated to eliminate its bromine content prior to being removed from the system, while the remaining hydrobromic acid solution is electrolyzed to regenerate aqueous bromine and produce hydrogen. Hydrobromic acid electrolysis requires less than half the energy required by water electrolysis and is an inherently flexible load that can shed or absorb excess power to balance supply and demand.

A method for separating and recovering carbon dioxide from ambient air includes continuously bringing ambient air into contact with a basic aqueous solution; electrodialysis of the solution using bipolar and anion-selective ion exchange membranes as well as recycling the depleted solution; separating CO.sub.2 from the enriched solution and recycling the solution depleted of CO.sub.2. The absorption is performed in an absorber, open basin, or a combination thereof. Separation is achieved by thermal desorption of CO.sub.2 by steam stripping to obtain a carbon dioxide/steam mixture; and/or by chemical reaction of the (hydrogen-) carbonate ions, in which the CO.sub.2 contained is converted into a water-insoluble salt or a gas and simultaneously removed from the solution. The pH of either obtained solution is measured before the recycling or before the separation, and is adjusted to a predetermined value. pH is measured and adjusted based on how absorption and separation are performed.

A carbon dioxide treatment apparatus includes: a capturing device that captures carbon dioxide; and an electrochemical reaction device that electrochemically reduces the carbon dioxide captured by the capturing device, and the electrochemical reaction device includes a first electrolytic cell that electrochemically reduces the carbon dioxide to carbon monoxide, and a second electrolytic cell that electrochemically reduces the carbon monoxide produced by the first electrolytic cell to ethylene.

Integrated systems comprising both i) heat and mass exchange systems and ii) electrolysis stacks are disclosed, together with related methods of use. The disclosed systems cool and/or dehumidify air using two streams of salt solutions as liquid desiccants.

The present disclosure provides systems and methods useful in capture of one more moieties (e.g., carbon dioxide) from a gas stream (i.e., direct air capture). In various embodiments, the systems and methods can utilize at least a scrubbing unit, a regeneration unit, and an electrolysis unit whereby an alkali solution can be used to strip the moiety (e.g., carbon dioxide) from the gas stream, the removed moiety can be regenerated and optionally purified for capture or other use, and a formed salt can be subjected to electrolysis to recycle the alkali solution back to the scrubber for re-use with simultaneous production of one or more further chemicals.

Provided herein are methods of removing carbon dioxide from an aqueous stream or gaseous stream by: contacting the gaseous stream comprising carbon dioxide, when present, with an aqueous solution comprising ions capable of forming an insoluble carbonate salt; contacting the aqueous solution comprising carbon dioxide with an electroactive mesh that induces its alkalinization thereby forcing the precipitation of a carbonate solid from the solution and thereby the removal of dissolved inorganic carbon by electrolysis; and removing the precipitated carbonate solids from the solution, or the surface of the mesh where they may deposit. Also provided herein are flow-through electrolytic reactors comprising an intake device in fluid connection with a rotating cylinder comprising an electroactive mesh, and a scraping device and/or liquid-spray based device for separating a solid from the mesh surface.

A controller unit is configured to control a recovery unit, an expeller unit, a collector unit and a connector unit. The controller unit is configured to place each of a first collector opening and closing device, a second collector opening and closing device and an expeller opening and closing device in a closed state and place a connector opening and closing device in an opened state and thereafter operate the expeller unit to expel a remaining gas from a collector pipe through a connector pipe and an expeller pipe to execute an exhausting process before the controller unit executes a recovering process by desorbing carbon dioxide from an electrochemical cell device and collecting the carbon dioxide at a utilization unit through the collector pipe after the desorbing of the carbon dioxide from the electrochemical cell device.

Systems and methods for at least partially removing carbon dioxide (CO.sub.2) from a feed gas comprising CO.sub.2 are generally provided.

A scrubber, an exhaust gas purification system comprising the scrubber, and an air purification method. The treatment water of the scrubber is plasma electrolytic water. The plasma electrolytic water is obtained after water is electrolyzed. The process of electrolysis is carried out in an electromagnetic water treatment device. The electromagnetic water treatment device comprises a cation exchange film, a water flow passage, at least one positive pole panel, at least one negative pole panel, and a magnetic device.