The present invention relates to a hydrogen gas production method, which includes: a first step of concentrating an aqueous solution containing an alkali metal formate; a second step of protonating at least a part of the alkali metal formate by electrodialysis to produce a formic acid; and a third step of decomposing the formic acid to produce a hydrogen gas.

Disclosed are electrochemical systems that include an electrodialyzer and a vapor-fed CO.sub.2 reduction (CO.sub.2R) cell to capture and convert CO.sub.2 from ocean water. The electrodialyzer includes a stack of bipolar membrane electrodialysis (BPMED) cells between end electrodes. The electrodialzyer incorporates monovalent cation exchange membranes (M-CEMs) that prevent the transfer of multivalent cations between adjacent cell compartments, allowing continuous recirculation of electrolytes and solutions, and thus providing a safer and more scaling-free electrodialysis system. In some embodiments, the electrodialyzer may be configured to replace the water-splitting reaction at end electrodes with one-electron, reversible redox couples in solution at the electrodes. As a result, in the entire electrodialyzer stack, there is no bond-making, bond-breaking reactions and there is no gas generation, which significantly simplifies the cell design and improves operational safety. The systems provide a unique technological pathway for CO.sub.2 capture and conversion from ocean water with only electrochemical processes.

Disclosed is a process for enriching silicate content in drinking water that includes separating raw water via reverse osmosis into a permeate comprising demineralised raw water and a retentate comprising mineral enriched raw water. The permeate is mixed with a water glass solution comprising sodium silicate and/or potassium silicate. An ion exchange process is used to reduce the concentration of sodium and/or potassium ions in at least part of the mixture. At least part of the retentate is supplied to the mixture after reducing the concentration of sodium and/or potassium ions to provide a silicate-enriched drinking water. Also disclosed is an apparatus for producing a drinking water enriched with silicate. The apparatus includes a reverse osmosis unit, a mixing unit, an ion exchanger, and a feed unit for feeding at least part of the retentate to the mixture after reducing the concentration of sodium and/or potassium ions.

A carbon dioxide electrolytic device includes: a carbon dioxide electrolysis cell having a cathode and an anode flow path, a cathode, an anode, and a first diaphragm; a first current regulator to supply a first current; a first gas/liquid separator to separate a first fluid from the anode flow path into a first liquid and gas; an electrodialysis cell having, first and second electrodes, first to fourth rooms, and second to fourth diaphragms; a second current regulator to supply a second current; at least one detector out of a first detector to detect a flow rate of the first gas or a concentration of carbon dioxide in the first gas, and a second detector to detect a pH or a concentration of at least one ion in the first fluid; and a first controller to regulate a second current, in accordance with at least one detection signal.

The present disclosure provides devices and methods of using same for cleansing a solution (e.g., a salt or used dialysis solution) of urea via electrooxidation, and more specifically to cleansing a renal therapy solution/dialysis solution of urea via electrooxidation so that the renal therapy solution/dialysis solution can be used or reused for treatment of a patient. In an embodiment, a device for the removal of urea from a fluid having urea to produce a cleansed fluid includes a urea decomposition unit and an electrodialysis unit.

A method of cleaning used dialysis fluid having urea to produce a cleaned dialysis fluid, the method including passing the used dialysis fluid having urea through a combination electrodialysis and urea oxidation cell, the cell including (i) a first set of electrodes for separation of the used dialysis fluid having urea into an acid stream and a basic stream, wherein the first set of electrodes includes an anode and a cathode; (ii) one or more second set of electrodes positioned to contact the basic stream with an electrocatalytic surface for decomposition of urea via electrooxidation, wherein the one or more second set of electrodes includes an anode and a cathode; and (iii) at least one power source to provide the first and second sets of electrodes with an electrical charge to activate the electrocatalytic surface.

A dual-membrane on-line generator for an acid or alkali solution is provided, including an upper electrolytic cell body (3), a middle electrolytic cell body (4) and a lower electrolytic cell body (5) which are clamped by an upper fastening steel plate (1) and a lower fastening steel plate (2), an upper regeneration liquid channel (A), a middle eluent channel (B) and a lower regeneration liquid channel (C) being provided on the middle electrolytic cell body (4).

This invention relates to an improved electrodialysis method for preparing an amino acid from a salt of the amino acid utilizing a three-compartment bipolar membrane electrodialysis process wherein an aqueous electrolyte comprising an exogenous acid is added to the acid compartment of a three-compartment bipolar membrane apparatus. The exogenous acid is different than the amino acid and typically has a pKa less than the pKa of the amino acid.

A method of cleaning used dialysis fluid having urea to produce a cleaned dialysis fluid, the method including passing the used dialysis fluid having urea through a combination electrodialysis and urea oxidation cell, the cell including (i) a first set of electrodes for separation of the used dialysis fluid having urea into an acid stream and a basic stream, wherein the first set of electrodes includes an anode and a cathode; (ii) one or more second set of electrodes positioned to contact the basic stream with an electrocatalytic surface for decomposition of urea via electrooxidation, wherein the one or more second set of electrodes includes an anode and a cathode; and (iii) at least one power source to provide the first and second sets of electrodes with an electrical charge to activate the electrocatalytic surface.

An acid component removal device for removing an acid component from an acid gas absorbent containing an amine, comprising: an anode; a cathode; and an electrodialysis structure having four compartments formed by arranging an first membrane which is either an anion exchange membrane or a cation exchange membrane, a second membrane which is a bipolar membrane, and a third membrane which is either an anion exchange membrane or a cation exchange membrane and which is the other of the first membrane, in this order, from the anode end to the cathode end between the anode and the cathode, with a space each between the membranes.