Disclosed herein are methods and systems that relate to oxidizing a metal ion of a metal oxyanion or a non-metal ion of a non-metal oxyanion from a lower oxidation state to a higher oxidation state at an anode and generate hydrogen gas at the cathode. The metal oxyanion with the metal ion in the higher oxidation state or the non-metal oxyanion with the non-metal ion in the higher oxidation state may be then subjected to a thermal reaction or a second electrochemical reaction, to form oxygen gas as well as to regenerate the metal oxyanion with the metal ion in the lower oxidation state or the non-metal oxyanion with the non-metal ion in the lower oxidation state, respectively.

An electrochemical reactor system adapted for producing a chemical product from a reactant includes (a) separate electrochemical and production cells and (b) a charge carrier compound in a catholyte adapted to effectively decouple the charging of the charge carrier compound in the electrochemical cell with the electrochemical conversion of a reactant to a desired chemical product in the production cell.

This publication relates to a method and a system for producing freshwater through a reverse osmosis process in a submerged membrane system requiring a differential pressure over the membrane system. The differential pressure is provided by introducing gas bubbles in the riser device (2) downstream the outlet (7) for fresh water in the riser device (2). The system comprises at least one submerged, reverse osmosis unit (1), with an inlet (4) for water and an outlet (7) for fresh water, a riser device (2) extending from the outlet (7) of the submerged membrane system to at, above or below sea level and a system for providing a low pressure side for the reverse osmosis process.

In one embodiment, a system includes a purification stage configured to purify an input gas stream prior to delivering the input gas stream to a reaction stage; and a collection stage configured to collect at least some ammonia from the reaction stage. The reaction stage is configured to reduce nitrogen into nitride; and convert at least some of the nitride into ammonia. In another embodiment, a separation membrane includes: an anode; a cathode electrically coupled to the anode; and a porous support material positioned between the anode and the cathode. The separation membrane is configured to reduce nitrogen into nitride; and facilitate hydrogenation of the nitride to form ammonia. In another embodiment, a method includes delivering an input gas stream comprising nitrogen to a separation membrane; reducing at least some of the nitrogen into nitride; and reacting at least some of the nitride with hydrogen-containing compound(s).

In one embodiment, a system includes a purification stage configured to purify an input gas stream prior to delivering the input gas stream to a reaction stage; and a collection stage configured to collect at least some ammonia from the reaction stage. The reaction stage is configured to reduce nitrogen into nitride; and convert at least some of the nitride into ammonia. In another embodiment, a separation membrane includes: an anode; a cathode electrically coupled to the anode; and a porous support material positioned between the anode and the cathode. The separation membrane is configured to reduce nitrogen into nitride; and facilitate hydrogenation of the nitride to form ammonia. In another embodiment, a method includes delivering an input gas stream comprising nitrogen to a separation membrane; reducing at least some of the nitrogen into nitride; and reacting at least some of the nitride with hydrogen-containing compound(s).

A method of preparing metal hydroxides from industrial wastes or alkaline rocks is provided. The method comprise subjecting a mixture comprising a solvent and a solid substrate to a stimulus in order to leach a metal cation from the solid substrate into the solvent, thereby forming a solution comprising the metal cation in the solvent; and contacting the solution of comprising the metal cation with a cathode, thereby electrolytically precipitating the metal hydroxide from the solution. The stimulus may be chemical, mechanical, or both.

A method of preparing metal hydroxides from industrial wastes or alkaline rocks is provided. The method comprise subjecting a mixture comprising a solvent and a solid substrate to a stimulus in order to leach a metal cation from the solid substrate into the solvent, thereby forming a solution comprising the metal cation in the solvent; and contacting the solution of comprising the metal cation with a cathode, thereby electrolytically precipitating the metal hydroxide from the solution. The stimulus may be chemical, mechanical, or both.

An alkaline water electrolysis system includes: a plurality of reaction chambers, each including a main electrode and an auxiliary electrode; a piston provided in each reaction chamber to change a volume of the reaction chamber through reciprocating motion; a drive motor; a connecting rod and a crankshaft installed to change rotational motion of the drive motor into reciprocating linear motion of the piston; a plurality of gas valves installed on an upper side of the reaction chamber to discharge hydrogen and oxygen generated in the reaction chamber through different paths, respectively; a pressure sensor installed in the reaction chamber; a controller configured to open and close the gas valves in response to a signal received from the pressure sensor; and an electrolyte supply apparatus provided to supply an electrolyte to the reaction chambers.

Disclosed are a carbon dioxide utilization system capable of producing electricity, hydrogen, and bicarbonate by utilizing carbon dioxide, which is a greenhouse gas, through a spontaneous electrochemical reaction without a separate external power source, and producing magnesium hydrogen carbonate by reacting the hydrogen carbonate ions with magnesium ions generated at an anode.

An alkaline water electrolysis system includes: a plurality of reaction chambers, each including a main electrode and an auxiliary electrode; a piston provided in each reaction chamber to change a volume of the reaction chamber through reciprocating motion; a drive motor; a connecting rod and a crankshaft installed to change rotational motion of the drive motor into reciprocating linear motion of the piston; a plurality of gas valves installed on an upper side of the reaction chamber to discharge hydrogen and oxygen generated in the reaction chamber through different paths, respectively; a pressure sensor installed in the reaction chamber; a controller configured to open and close the gas valves in response to a signal received from the pressure sensor; and an electrolyte supply apparatus provided to supply an electrolyte to the reaction chambers.