The present invention can provide a new method for fixing carbon dioxide. The method for fixing carbon dioxide of the present invention includes a contact step of bringing a mixed liquid containing sodium hydroxide and further containing at least one of a chloride of a Group 2 element or a chloride of a divalent metal element into contact with a gas containing carbon dioxide, wherein in the contact step, the mixed liquid and the gas are brought into contact with each other by feeding the gas into the mixed liquid.

The present invention provides a new method for fixing carbon dioxide. The method for fixing carbon dioxide of the present invention includes: a first contact step of bringing a solution containing sodium hydroxide into contact with a gas containing carbon dioxide; and a second contact step of adding at least one of a chloride of a Group 2 element or a chloride of a divalent metal element to the solution after the first contact step.

Shippable modular units configured for use in sequestering CO.sub.2 are provided. Aspects of the units include a support having one or more of: a CO.sub.2 gas/liquid contactor subunit, a carbonate production subunit and an alkali enrichment subunit; associated therewith. Also provided are systems made up of one or more such modular units, and methods for using the units/systems in CO.sub.2 sequestration protocols.

Shippable modular units configured for use in sequestering CO.sub.2 are provided. Aspects of the units include a support having one or more of: a CO.sub.2 gas/liquid contactor subunit, a carbonate production subunit and an alkali enrichment subunit; associated therewith. Also provided are systems made up of one or more such modular units, and methods for using the units/systems in CO.sub.2 sequestration protocols.

Methods and systems for producing hydrogen substantially without greenhouse gas emissions, one method including producing a product gas comprising hydrogen and carbon dioxide from a hydrocarbon fuel source; separating hydrogen from the product gas to create a hydrogen product stream and a byproduct stream; injecting the byproduct stream into a reservoir containing mafic rock; and allowing components of the byproduct stream to react in situ with components of the mafic rock to precipitate and store components of the byproduct stream in the reservoir.

The invention relates to a process for preparing alkali carbonate/bicarbonate salts, comprising continuously feeding aqueous alkali hydroxide solution into a gas-liquid contactor; forcing incoming CO.sub.2-containing gas stream through a sparging device submerged in the gas-liquid contactor below the surface level of the aqueous alkali hydroxide solution, to generate bubbles and/or microbubbles; adding hydrogen peroxide in proximity to orifices of the sparging device, from which the bubbles and/or microbubbles evolve, wherein the supply of hydrogen peroxide is adjusted to decrease alkali carbonate formation and increase alkali bicarbonate formation; and continuously discharging an effluent from the gas-liquid contactor and recovering therefrom carbonate and bicarbonate alkali salts predominated by the bicarbonate component. A gas liquid-contactor and an apparatus are also provided by the invention.

The invention relates to a process for preparing alkali carbonate/bicarbonate salts, comprising continuously feeding aqueous alkali hydroxide solution into a gas-liquid contactor; forcing incoming CO.sub.2-containing gas stream through a sparging device submerged in the gas-liquid contactor below the surface level of the aqueous alkali hydroxide solution, to generate bubbles and/or microbubbles; adding hydrogen peroxide in proximity to orifices of the sparging device, from which the bubbles and/or microbubbles evolve, wherein the supply of hydrogen peroxide is adjusted to decrease alkali carbonate formation and increase alkali bicarbonate formation; and continuously discharging an effluent from the gas-liquid contactor and recovering therefrom carbonate and bicarbonate alkali salts predominated by the bicarbonate component. A gas liquid-contactor and an apparatus are also provided by the invention.

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.

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 method of preparing a transparent zinc carbonate is disclosed. The method includes dissolving a zinc source in aqueous ammonium carbonate, removing metal impurities from the solution, injecting CO.sub.2 into the zinc ammonia carbonate solution, heating a resulting slurry to a temperature of about 100° C. or more until the ammonia is substantially absent from the solution, and drying the resulting zinc carbonate at a temperature from around 150° C. to 300° C. for a length of time that removes water, but retains a significant part of the CO.sub.2 content. The ammonia and the carbon dioxide are present in the aqueous solution in a ratio by moles or by weight effective to dissolve the zinc. A nano zinc oxide can be prepared by drying the zinc carbonate at a temperature of 300-400° C. for a length of time sufficient to remove substantially all of the CO.sub.2.