An alkaline aqueous ferric iron salt solution is disclosed. Generally, the alkaline aqueous ferric iron salt solution comprises ferric ions (Fe.sup.3+), potassium ions (K.sup.+), carbonate ions (CO.sub.3.sup.2−), bicarbonate ions (HCO.sub.3.sup.−), hydroxide ions (OH.sup.−), optionally nitrate ions (NO.sub.3.sup.−). Further, a molar ratio of the potassium ions to the ferric ions is generally at least 5.0. The ferric iron is complexed with carbonate, bicarbonate or both to form a water-soluble complex that is anionic in nature and highly soluble in the alkaline aqueous ferric iron salt solution at pH above 8.5, and a pH of the alkaline aqueous ferric iron salt solution is at least 8.5.

The removal of acid gases (e.g., non-carbon dioxide acid gases) using sorbents that include salts in molten form, and related systems and methods, are generally described.

Novel methods for pretreating a rare-gas-containing stream exiting an etch chamber followed by recovering the rare gas from the pre-treated, rare-gas containing stream are disclosed. More particularly, the invention relates to the pretreatment and recovery of a rare gas, such as xenon or krypton, from a nitrogen-based exhaust stream with specific gaseous impurities generated during an etch process that is performed as part of a semiconductor fabrication process.

A system for removing undesirable compounds from contaminated air includes a biofilter having an alkaline material introduction system and a fuzzy-logic based controller. A contaminant, such as hydrogen sulfide, is removed from contaminated air by passing the contaminated air through the biofilter.

A method for preparing hydrogen sulfide from sulfur dioxide by electrochemical reduction includes electrochemically reducing sulfur dioxide absorbed in an aqueous solution into gaseous hydrogen sulfide with a membrane electrode, resulting in efficient and selective conversion of the sulfur dioxide absorbed in the aqueous solution into the hydrogen sulfide to avoid a deactivation of a cathode due to colloidal sulfur produced on the cathode and adhesion onto a surface of the cathode, wherein the method is carried out at ambient temperature and normal pressure without addition of a reducing agent, having no waste salts produced, and is simple in operation, and is convenient for large-scale application.

Methods and apparatus incorporating porous metallic electrodes for electrolytic conversion of carbon-containing ions are disclosed. A electrochemical cell has an anode, a porous metallic electrode which serves as a cathode, and an ion exchange membrane between the anode and the porous metallic electrode. Water dissociates into hydroxide ions and hydrogen ions at the ion exchange membrane. The hydroxide ions permeate towards the anode, and the hydrogen ions permeate towards the porous metallic electrode. A carbon-containing solution is supplied to the porous metallic electrode. The carbon-containing solution reacts with the hydrogen ions to form one or more carbon-containing intermediate products. One of the carbon-containing intermediate products participate in a reduction reaction at the porous metallic electrode to form one or more carbon-containing resulting products. In some embodiments, the carbon-containing solution comprises a solution containing bicarbonate. One application of the methods and apparatus is in the field of carbon capture.

An oxidation resistant absorbent for capturing carbon dioxide from a gas stream. The oxidation resistant absorbent includes an alkanolamine with a weight percent in a range of 10 wt. % to 35 wt. % to a total amount of the oxidation resistant absorbent, a base with a weight percent in a range of 1 wt. % to 15 wt. % to a total amount of the oxidation resistant absorbent, a plurality of nanoparticles with a weight percent in a range of 0.1 wt. % to 3 wt. % to a total amount of the oxidation resistant absorbent, and water.

The present disclosure provides a system for capturing carbon from air based on bipolar membrane electrodialysis, which includes a first cation exchange membrane, a bipolar membrane and a second cation exchange membrane arranged in sequence, where a desorption chamber is arranged between the first cation exchange membrane and the bipolar membrane, and an absorption chamber is arranged between the bipolar membrane and the second cation exchange membrane; and a cathode reaction chamber is arranged on the other side of the first cation exchange membrane, and an anode reaction chamber is arranged on the other side of the second cation exchange membrane. The system improves carbon capture rate and capture purity, and can be adapted to various scenarios.

The present disclosure relates to a device and method based on an electrically-driven chemical carbon pump combined cycle for a diluted carbon source. The device includes: an electrolytic cell and a cell structure. The electrolytic cell includes a cathode reaction chamber, a CO.sub.2 desorption chamber, a CO.sub.2 absorption chamber, and an anode reaction chamber that are connected in sequence. The CO.sub.2 desorption chamber and the CO.sub.2 absorption chamber are communicated through a bipolar membrane (BPM). The cell structure includes: a negative electrode, a positive electrode, a positive region, and a negative region. The negative electrode is arranged in the negative region, and the positive electrode is arranged in the positive region. The negative electrode is connected with the cathode reaction chamber, and the positive electrode is connected with the anode reaction chamber. A liquid outlet of the negative region is communicated with a liquid inlet of the cathode reaction chamber. A liquid inlet of the negative region is communicated with a liquid outlet of the cathode reaction chamber. A liquid outlet of the positive region is communicated with a liquid inlet of the anode reaction chamber.

The present invention relates to an air purifier (1) comprising a body (2) having an inlet opening (I) through which the air in the environment is sucked and an outlet opening (O) through which the cleaned air is released, and a CO.sub.2 adsorption unit (3) which is provided on the body (2), which chemically adsorbs the carbon dioxide in the air taken into the body (2) by being supplied with air together with a basic solution and which has an inlet tube (5).