Disclosed is a system for producing magnesium hydroxide including: a generation unit; and a recovery unit connected to the generation unit, wherein the generation unit has a reaction tank in which a calcium hydroxide slurry is added to water to be treated containing magnesium ions to crystallize magnesium hydroxide and to obtain a reaction slurry containing particles of magnesium hydroxide, and a sedimentation tank in which the reaction slurry is reserved to sediment the particles and to separate the reaction slurry into a separation slurry containing the particles at a high concentration and a separation liquid containing the particles at a low concentration, and wherein, in the recovery unit, an alkaline aqueous solution is added to the separation liquid to crystallize magnesium hydroxide and to obtain the reaction slurry and then the reaction slurry is reserved to sediment the particles and to recover the sedimented particles.

Disclosed is a system for producing magnesium hydroxide including: a generation unit; and a recovery unit connected to the generation unit, wherein the generation unit has a reaction tank in which a calcium hydroxide slurry is added to water to be treated containing magnesium ions to crystallize magnesium hydroxide and to obtain a reaction slurry containing particles of magnesium hydroxide, and a sedimentation tank in which the reaction slurry is reserved to sediment the particles and to separate the reaction slurry into a separation slurry containing the particles at a high concentration and a separation liquid containing the particles at a low concentration, and wherein, in the recovery unit, an alkaline aqueous solution is added to the separation liquid to crystallize magnesium hydroxide and to obtain the reaction slurry and then the reaction slurry is reserved to sediment the particles and to recover the sedimented particles.

A method of photocatalytic degradation includes contacting a nanocomposite with a solution including one or more pollutants. The nanocomposite is a graphite-phase carbon nitride copper oxide and magnesium aluminum oxide (g-C.sub.3N.sub.4@CuO/MgAl.sub.2O.sub.4) material and includes a graphite-phase carbon nitride (g-C.sub.3N.sub.4) in an amount of 2 to 20 percent by weight (wt. %), copper oxide in an amount of 1 to 10 wt. %, and magnesium aluminum oxide (MgAl.sub.2O.sub.4) in an amount of 75 to 95 wt. % based on a total weight of the g-C.sub.3N.sub.4@CuO/MgAl.sub.2O.sub.4 material. The method further includes irradiating the nanocomposite with light having a wavelength of 400 to 800 nm in the absence of UV light to photocatalytically degrade the one or more pollutants in the solution.

A method of photocatalytic degradation includes contacting a nanocomposite with a solution including one or more pollutants. The nanocomposite is a graphite-phase carbon nitride copper oxide and magnesium aluminum oxide (g-C.sub.3N.sub.4@CuO/MgAl.sub.2O.sub.4) material and includes a graphite-phase carbon nitride (g-C.sub.3N.sub.4) in an amount of 2 to 20 percent by weight (wt. %), copper oxide in an amount of 1 to 10 wt. %, and magnesium aluminum oxide (MgAl.sub.2O.sub.4) in an amount of 75 to 95 wt. % based on a total weight of the g-C.sub.3N.sub.4@CuO/MgAl.sub.2O.sub.4 material. The method further includes irradiating the nanocomposite with light having a wavelength of 400 to 800 nm in the absence of UV light to photocatalytically degrade the one or more pollutants in the solution.

Processes are provided in which successive steps of hydrometallurgical value extraction may be carried out using the products of carbon capture and an electrolytic reagent-generating process. The electrolytic process provides an acid leachant and an alkali hydroxide, with the alkali hydroxide then available for use either directly as a precipitant in the hydrometallurgical steps, or available for conversion by carbon capture to an alkali metal carbonate that can in turn be used as the precipitant in the selective hydrometallurgical steps.

Processes are provided in which successive steps of hydrometallurgical value extraction may be carried out using the products of carbon capture and an electrolytic reagent-generating process. The electrolytic process provides an acid leachant and an alkali hydroxide, with the alkali hydroxide then available for use either directly as a precipitant in the hydrometallurgical steps, or available for conversion by carbon capture to an alkali metal carbonate that can in turn be used as the precipitant in the selective hydrometallurgical steps.

A process and system are disclosed for producing lithium oxide from lithium nitrate. In the process and system, the lithium nitrate is thermally decomposed in a manner such that a fraction of the lithium nitrate forms lithium oxide, and such that a remaining fraction of the lithium nitrate does not decompose to lithium oxide. The thermal decomposition may be terminated after a determined time period to ensure that there is a remaining fraction of lithium nitrate and to thereby produce a lithium oxide in lithium nitrate product. The lithium oxide in lithium nitrate product may have one or more transition-metal oxides, hydroxides, carbonates or nitrates added thereto to form a battery electrode. The lithium oxide in lithium nitrate product may alternatively be subjected to carbothermal reduction to produce lithium metal.

Divalent ions are extracted from solids by leaching to form a divalent ion-containing solution. The divalent ion-containing solution is subjected to concentration to form a concentrated divalent ion-containing solution. Precipitation of a divalent ion hydroxide salt is induced from the concentrated divalent ion-containing solution. In other cases, the concentrated divalent ion-containing solution is exposed to carbon dioxide to induce precipitation of a divalent ion carbonate salt.

Divalent ions are extracted from solids by leaching to form a divalent ion-containing solution. The divalent ion-containing solution is subjected to concentration to form a concentrated divalent ion-containing solution. Precipitation of a divalent ion hydroxide salt is induced from the concentrated divalent ion-containing solution. In other cases, the concentrated divalent ion-containing solution is exposed to carbon dioxide to induce precipitation of a divalent ion carbonate salt.