Systems and methods for the production of hydroxides

Abstract

The present disclosure relates to systems and methods for preparing Ca(OH)2 and / or Mg(OH)2.

Description

[0001] Atty. Docket No.: UCH-40925

[0002] UCLA Ref. No.: [UCLA 2024-285-1] WO

[0003] SYSTEMS AND METHODS FOR THE PRODUCTION OF HYDROXIDES

[0004] CROSS REFERENCE TO RELATED APPLICATIONS

[0005] This application claims the benefit of priority to U.S. Provisional Application No. 63 / 713,684, filed October 30, 2024, the contents of which are herein incorporated by reference in their entirety.

[0006] BACKGROUND

[0007] Ca(OH)2 and Mg(OH)2 are each important chemical feedstocks that may be used for the production of cementitious materials, and for carbon dioxide capture and sequestration. Traditional industrial processes for producing Ca(OH)2 and / or Mg(0H)2 are highly energy- and carbon-intensive and / or require a large number of process steps. Accordingly, there is a need for improved methods of producing Ca(OH)2 and / or Mg(0H)2.

[0008] SUMMARY OF THE INVENTION

[0009] In certain aspects, provided herein are systems and methods for producing Ca(OH)2. In some aspects, provided herein are systems and methods for producing Mg(0H)2. In certain aspects, provided herein are systems and methods for producing both Ca(OH)2 and Mg(0H)2.

[0010] In certain aspects, provided herein are systems comprising: a first electrochemical cell, comprising: a first cathodic chamber, comprising: a first cathode; a target ion stream inlet; a first cathodic gas outlet; and a first hydroxide mixture outlet; a first anodic chamber, comprising: a first anode; a first electrolyte inlet; a first anodic gas outlet; at least one primary acidic anolyte outlet; a first membrane disposed between the first cathodic chamber and the first anodic chamber; a dissolution chamber, comprising: an acidic anolyte inlet coupled to the at least one primary acidic anolyte outlet; Atty. Docket No.: UCH-40925

[0011] UCLA Ref. No.: [UCLA 2024-285-1] WO a target ion carbonate feed inlet; a gas outlet; and a target ion stream outlet coupled to the target ion stream inlet of the cathodic chamber; and a first hydroxide isolation chamber, comprising: a first hydroxide mixture inlet coupled to the first hydroxide mixture outlet; a first hydroxide collection outlet; and a second hydroxide mixture outlet; wherein the first cathodic chamber and the first anodic chamber are in ionic communication.

[0012] In certain aspects, provided herein are methods of preparing a hydroxide of at least one target ion, comprising: providing a first electrolyte solution comprising a non-target cation to a first anodic chamber of a first electrochemical cell, the first electrochemical cell further comprising: a first anode disposed within the first anodic chamber; a first cathodic chamber, comprising a first cathode; and a first membrane disposed between and configured to separate the first cathodic chamber and the first anodic chamber; wherein the first anodic chamber and the first cathodic chamber are in fluid communication; performing a first electrochemical process, comprising: applying a first voltage to the first cathode and the first anode; thereby producing: a first acidic anolyte and an anodic gas at the first anode; and a first hydroxide mixture and a cathodic gas at the first cathode; wherein the first acidic anolyte comprises an acid, and the first hydroxide mixture comprises a first hydroxide of at least one target ion and a hydroxide of the non-target ion; separating the first acidic anolyte into a first portion and a second portion; contacting the first portion of the first acidic anolyte with a source of the at least one target ion , thereby producing a CO2 stream and a target ion stream comprising the at least one target ion, wherein the CO2 stream comprises CO2; providing the target ion stream to the first cathodic chamber; and Atty. Docket No.: UCH-40925

[0013] UCLA Ref. No.: [UCLA 2024-285-1] WO separating the first hydroxide of the at least one target ion from the first hydroxide mixture, thereby producing a second hydroxide mixture comprising the hydroxide of the nontarget ion.

[0014] BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Fig- 1 shows a process flow diagram detailing an exemplary system and process of the disclosure configured to produce Ca(0H)2. Air is used as the stripping gas, and the electrolyte comprises NaCl. The system of Fig. 1 also comprises the step of removing CO2 from the CO2 stream using NaOH from the catholyte, thereby producing Na2COs or NaHCOs as a co-product.

[0016] Fig- 2 shows a breakdown of the energy consumption of the exemplary process shown in Fig. 1 by method steps. Ca(0H)2 production in the cathodic chamber consumes about 64% of the total energy of the process, while removal of CO2 from the CO2 stream consumes about 35% of the total energy consumed by the process. Neutralizing the solution flowing into the cathode compartment and purging NaHCCf each account for less than 1% of the total energy consumption.

[0017] Fig- 3 shows a process flow diagram detailing an exemplary system and process of the disclosure configured to produce Mg(0H)2 and Ca(0H)2. The system according to this embodiment of the disclosure includes a solid source of Ca2+and Mg2+(e.g., limestone, which may comprise Mg2+), which is dissolved by acid generated in the anodic chambers of two electrochemical cells configured in series. The two electrochemical cells in series are configured to produce Mg(0H)2 in the cathodic chamber of the first electrochemical cell (e.g., wherein the pH in the first cathodic chamber is approximately 10) and Ca(OH)2 in the cathodic chamber of the second electrochemical cell (e.g., wherein the pH in the second cathodic chamber is approximately 12.5). Additionally, an electrolyte comprising Mg2+may be used. In general, sequential electrochemical cells may be advantageous in applications involving higher concentrations of Mg2+and Ca2+, though a single electrochemical cell may also be used. A similar configuration may be used to produce Mg(OH)2 or Ca(OH)2, or a combination thereof.

[0018] Fig. 4 shows a process flow diagram detailing an exemplary system and process of the disclosure configured to produce Mg(OH)2 and Ca(OH)2. The system according to this embodiment of the disclosure includes a solid source of Ca2+and Mg2+(e.g., limestone comprising Mg2+), which is dissolved by acid generated in the anodic chambers of two electrochemical cells configured in series. The two electrochemical cells in series are configured to produce Mg(OH)2 in the cathodic chamber of the first electrochemical cell (e.g., Atty. Docket No.: UCH-40925

[0019] UCLA Ref. No.: [UCLA 2024-285-1] WO wherein the pH in the first cathodic chamber is approximately 10) and Ca(OH)2 in the cathodic chamber of the second electrochemical cell (e.g., wherein the pH in the second cathodic chamber is approximately 12.5). Additionally, an electrolyte comprising Mg2+may be used. In this embodiment, the electrochemical cells are configured to produce an anolyte in a counterflow electrolyzer arrangement. This provides the advantage of reducing the average pH gradient and increasing efficiency of the system by reducing H+crossover. Unless otherwise noted, symbols for system components are defined as shown in Fig. 3.

[0020] Fig- 5 shows a process flow diagram detailing an exemplary system and process of the disclosure configured to produce Mg(0H)2 and Ca(OH)2. The system according to this exemplary embodiment of the disclosure includes a solid source of Ca2+and Mg2+(e.g., limestone comprising Mg2+), which is dissolved by acid generated in the anodic chambers of a single electrochemical cell. In this exemplary embodiment, a single electrochemical cell is configured to produce Ca(OH)2 and Mg(0H)2, and a base recycle loop is incorporated that is configured to allow for the isolation of Mg(0H)2. In general, a single electrochemical cell with a base recycle loop will be advantageous in applications involving Mg2+or Ca2+as the dominant input species, or if only one of the two solid products is sought to be produced. Unless otherwise noted, symbols for system components are defined as shown in Fig. 3.

[0021] Fig- 6 is a process flow diagram of an exemplary process for the production of 5.5 tonnes of Ca(OH)2 per day.

[0022] DETAILED DESCRIPTION OF THE INVENTION

[0023] The systems and methods of the present disclosure have the potential to reduce the carbon intensity of cement production by, in the net reaction, producing calcium hydroxide and / or magnesium hydroxide, water, and sodium bicarbonate (aq) from limestone and sodium chloride with low (e.g., zero or near-zero) corresponding CO2 emissions, via electrochemical acid and base generation while co-generating hydrogen gas and oxygen gas. Depending on the anode chemistry used, chlorine gas may be co-produced or suppressed.

[0024] In certain embodiments, the systems and methods provided herein use an oxidizable or oxidation-stable electrolyte (e.g., NaCl, KC1, NaCIC , etc.; or any other soluble salt comprising a cation that forms a soluble hydroxide salt and soluble carbonate salt), and / or, optionally, an ion exchange medium, to produce HC1 in the anode compartment of an electrolyzer using oxygen selective anodes while Na+ions diffuse through the membrane. In preferred Atty. Docket No.: UCH-40925

[0025] UCLA Ref. No.: [UCLA 2024-285-1] WO embodiments, the electrolyte may comprise a chloride salt of an element which also forms water-soluble carbonates and hydroxides.

[0026] In certain embodiments, a portion of the acidified anolyte / acidified electrolyte stream is discharged, while the remaining portion of the acidified anolyte / acidified electrolyte stream is used to dissolve a solid comprising the target ion (e.g., limestone if the target ion is Ca2+and a limestone comprising Mg if the target ions are Ca2+and Mg2+). The ratio of the portion that is used to dissolve the solid comprising the target ion (the first portion) to the portion that is discharged (the second portion) (e.g., v / v, wt / wt, or mol / mol) is referred to herein as the “split ratio.” This split ratio provides a useful handle by which the overall mass balance of the process may be controlled. In addition, the second portion of the acidified anolyte / acidified electrolyte stream may be neutralized or used, in some embodiments, in downstream processes, including as a cleaning agent.

[0027] In some embodiments, the dissolving of the solid comprising the target ion is assisted by the introduction of air (or another low-CO? stripping gas), which can be conducted either simultaneously or in a 2-step process.

[0028] In certain embodiments, the dissolving of limestone may be conducted in multiple steps / reactors. In certain embodiments, dissolving the limestone comprises a sequence of multiple reactors and recycle loops where undissolved limestone particles remaining after a first dissolution step are re-circulated and contacted first with the fresh acidic anolyte. In a second step / reactor, fresh limestone (generally more reactive than the hard-to-dissolve particles) can be added, affording the advantage of increased limestone utilization. The fresh limestone may increase the pH of the resulting calcium stream and any undissolved limestone may be recycled.

[0029] The dissolution and degassing of CO2 is preferentially done in a process configuration that leads to an increase in pH of the resulting target ion stream, e.g., to about 6. This pH range is advantageous for the alkalinization of this now target-ion-enriched stream in the cathode compartment of the electrolyzer. Contacting this enriched stream e.g., comprising aqueous CaCh and / or MgCh) with the cathode leads to the production of Ca(0H)2 within or outside of the electrolyzer. Subsequent separation of the target hydroxide (e.g., Mg(0H)2 and / or Ca(0H)2) product (e.g., by filtration, settling / clarifying, or other suitable means) leaves an alkaline liquid stream (e.g., comprising aqueous NaOH and / or the second target hydroxide) which is used to produce the second target hydroxide product and / or re-capture the degassed CO2 from limestone’s dissolution. Atty. Docket No.: UCH-40925

[0030] UCLA Ref. No.: [UCLA 2024-285-1] WO

[0031] Additionally, the split ratio of the HC1 streams can be adjusted to alter the CO2 capture amount and increase OH' production efficiency or to allow for direct air capture (DAC) of CO2 to be incorporated into the processes described herein. Thus, in some embodiments, the overall process allows the production of one or more target hydroxides from a solid comprising one or more target ions with no net CO2 emissions. In certain embodiments, the overall process allows the production of Ca(OH)2 from limestone with no net CO2 emissions. In some embodiments, the overall process allows the production of Mg(OH)2 from limestone comprising Mg with no net CO2 emissions. In certain embodiments, the overall process allows the production of Ca(OH)2 and Mg(OH)2 from limestone comprising Mg with no net CO2 emissions.

[0032] In certain embodiments, a membrane barrier separates the catholyte and the anolyte in order to: (1) Prevent neutralization reactions from occurring between the catholyte and anolyte (i.e., by H+ion crossover), thus maintaining distinct anode and cathode pH values and a cathode pH that is approximately constant, as well as favorable conditions for Ca(OH)2 and / or Mg(OH)2 production; (2) Promote higher reactor energy efficiency; and (3) Facilitate the collection of gas streams (H2 and O2).

[0033] Production of Ch gas, which is a byproduct of electrolysis when the solution used contains a high concentration of Cl' ions (e.g., in electrolyte solutions comprising NaCl), can be avoided if an oxygen-selective electrode is used. If such an electrode is not used, the gas stream comprising Ch can be directed into a granulated activated carbon tank, or into a caustic scrubber, to reduce the chlorine concentration. In some embodiments, the caustic for this scrubber is supplied internally from the catholyte, and may be introduced either before or after solid hydroxide product separation.

[0034] In the present disclosure, certain components of these systems are described as being “coupled” to one another. As will be appreciated, the term “coupled” as used herein describes components that are operationally linked to one another, but does not preclude the presence of intervening components between those said to be coupled to one another. In certain embodiments, components that are described as “coupled” to one another are in fluidic and / or gaseous communication. Additionally, as will be appreciated, various system components are described as “having” certain features. Such descriptions do not preclude, and specifically contemplate, the presence of additional features, such as inlets, outlets, valves, control mechanisms, measurement devices, heating and / or cooling systems, etc. Additionally, in the systems of the present disclosure, certain components are described as having one or more outlets or inlets. Such outlets and inlets may represent separate structural elements, or may be Atty. Docket No.: UCH-40925

[0035] UCLA Ref. No.: [UCLA 2024-285-1] WO combined into a single inlet or outlet as suitable. The person of skill in the art will recognize that, once the important features and operating conditions of systems such as those described herein are understood, the detailed design and operation of such systems involved many choices, such as specific reagent flows, separation steps, etc. While the present disclosure provides a number of specific embodiments, any suitable combination of these design choices may be made.

[0036] In certain aspects, a system is provided, comprising: a first electrochemical cell, comprising: a first cathodic chamber, comprising: a first cathode; a target ion stream inlet; a first cathodic gas outlet; and a first hydroxide mixture outlet; a first anodic chamber, comprising: a first anode; a first electrolyte inlet; a first anodic gas outlet; at least one primary acidic anolyte outlet; a first membrane disposed between the first cathodic chamber and the first anodic chamber; a dissolution chamber, comprising: an acidic anolyte inlet coupled to the at least one primary acidic anolyte outlet; a target ion carbonate feed inlet; a gas outlet; and a target ion stream outlet coupled to the target ion stream inlet of the cathodic chamber; and a first hydroxide isolation chamber, comprising: a first hydroxide mixture inlet coupled to the first hydroxide mixture outlet; a first hydroxide collection outlet; and a second hydroxide mixture outlet; wherein the first cathodic chamber and the first anodic chamber are in ionic communication.

[0037] In certain embodiments, the anodic chamber comprises at least one acidic anolyte outlet. In certain embodiments, the at least one primary acidic anolyte outlet is configured to Atty. Docket No.: UCH-40925

[0038] UCLA Ref. No.: [UCLA 2024-285-1] WO separate a first acidic anolyte from the first anodic chamber into a first acidic anolyte portion and second acidic anolyte portion. In certain embodiments, the anodic chamber comprises a first acidic anolyte outlet and a second acidic anolyte outlet.

[0039] In other embodiments, the anodic chamber comprises one acidic anolyte outlet, which comprises a first splitting outlet and a second splitting outlet. In certain embodiments, the system further comprises a device coupled to the at least one primary acidic anolyte outlet and configured to the adjust a ratio of the first acidic anolyte portion to the second acidic anolyte portion. As will be appreciated by one of skill in the art, these outlets may be configured to divide an acidic anolyte into a first acidic anolyte portion and a second acidic anolyte portion, provide the first acidic anolyte portion to the dissolution chamber, and to discharge the second acidic anolyte portion of the acidic anolyte. The configuration of the first acidic anolyte outlet and second acidic anolyte outlet may be adjusted to control the ratio of the first portion to the second portion (the split ratio), affording the various advantages discussed above. In certain embodiments, systems of the disclosure further comprise a device configured to control and adjust the ratio of the first portion to the second portion (the split ratio). In certain embodiments, systems of the disclosure further comprise a controller configured to control and adjust the ratio of the first portion to the second portion (the split ratio). In some embodiments, the split ratio may be manually controlled and adjusted using the various outlets described above.

[0040] In certain embodiments, the dissolution chamber is incorporated into the anodic chamber, such that the anodic chamber further comprises a stripping gas inlet; a carbonate feed inlet; a CO2 stream outlet; and a target ion stream outlet coupled to the feed stream inlet of the cathodic chamber. In further embodiments, the anodic chamber is configured to contact the acidic anolyte with a target ion source (e.g., limestone) within the anodic chamber, thereby generating a target ion stream comprising at least one target ion (e.g., Ca2+or Mg2+, or a combination thereof).

[0041] In certain embodiments, systems of the disclosure comprise a first acidic anolyte outlet and a second acidic anolyte outlet. In certain embodiments, systems of the present disclosure comprise one acidic anolyte outlet. In some such embodiments, the acidic anolyte outlet further comprises a first acidic anolyte portion outlet and a second acidic anolyte portion outlet, wherein the first acidic anolyte portion outlet is coupled to the acidic anolyte inlet of the dissolution chamber. In certain embodiments, the first anodic chamber comprises a first primary acidic anolyte outlet and a second primary acidic anolyte outlet, and the first primary acidic anolyte outlet is coupled to the acidic anolyte inlet of the dissolution chamber. For Atty. Docket No.: UCH-40925

[0042] UCLA Ref. No.: [UCLA 2024-285-1] WO example, the first primary acidic anolyte outlet may be configured to provide the first acidic anolyte portion to the dissolution chamber, and / or the second primary acidic anolyte outlet may be configured to discharge the second acidic anolyte portion. Analogously, the first primary portion outlet may be configured to provide the first portion of the acidic anolyte to the dissolution chamber, and / or the second primary portion outlet may be configured to discharge the second portion of the acidic anolyte.

[0043] As will be appreciated by one of skill in the art, first acidic anolyte portion outlet and a second acidic anolyte portion outlet may be arranged in a number of configurations in systems of the disclosure. Non-limiting examples of suitable acidic anolyte outlets include three-way joints such as a Y-joint or T-Joint, a three-way valve (e.g., T-type three-way valves), and a T- joint. The splitting device has the functionality to split the anolyte at a split ratio ranging from 0.5 / 99.5 to 99.5 / 0.5 with a high accuracy and precision for ratios in the range from about 30 / 70 to about 50 / 50. Additionally, the splitting device and the resulting split ratio are controllable by a suitable process control system to adjust the split ratio rapidly in response to changes in the operating status of the plant. Alternatively, the splitting can occur in a buffer tank with two outlets each of the outlets connected to a pump that is controlled by a control system.

[0044] The first hydroxide isolation chamber may be configured to separate Ca(OH)2 and / or Mg(0H)2 from the first hydroxide mixture.

[0045] In certain embodiments, the system further comprises: a second hydroxide isolation chamber, comprising: a second hydroxide mixture inlet coupled to the second hydroxide mixture outlet; a second hydroxide collection outlet; and a third hydroxide mixture outlet. In certain such embodiments, the system further comprises a hydroxide precipitation chamber disposed between the first hydroxide isolation chamber and the second hydroxide isolation chamber, the hydroxide precipitation chamber comprising: a first precipitation chamber inlet coupled to the second hydroxide mixture outlet; a second precipitation chamber inlet coupled to the target ion stream outlet; a precipitation chamber outlet coupled to the second hydroxide mixture inlet of the second hydroxide isolation chamber.

[0046] In certain embodiments, the dissolution chamber further comprises a stripping gas inlet. In certain embodiments, the system comprises a single electrochemical cell.

[0047] In certain embodiments, systems of the disclosure comprise two electrochemical cells (e.g., electrolyzers) that are each configured to produce a hydroxide of a target ion from a mixture comprising at least two target ions. As will be understood by one of ordinary skill in the art, the pH of the catholyte solutions in each of the electrochemical cells may be maintained Atty. Docket No.: UCH-40925

[0048] UCLA Ref. No.: [UCLA 2024-285-1] WO at a value that is favorable for the selective precipitation of one hydroxide species over another - allowing the precipitation of a distinct hydroxide species in each electrolyzer [e.g., Mg(OH)2 in a first electrochemical cell and Ca(OH)2 in a second electrochemical cell] or only one hydroxide species e.g., only Ca(OH)2). For example, a catholyte pH of about 10 favors production and precipitation of Mg(OH)2 from solutions comprising Mg(OH)2 and Ca(OH)2. Precipitation of Ca(OH)2 does not occur until a pH of about 12.5 is reached. Thus, sequential recovery of Mg(OH)2 and Ca(OH)2 from solutions comprising Mg(OH)2 and Ca(OH)2 is possible, whereby Mg(OH)2 is recovered first when increasing the pH from low to high. One of ordinary skill in the art will readily understand how to configure the systems of the disclosure (e.g., by selecting suitable operating conditions and system components) to selectively produce a hydroxide of a first target ion in a first electrochemical cell and a hydroxide of a second target ion in a second electrochemical cell.

[0049] In certain embodiments, the second electrochemical cell comprises: a second cathodic chamber, comprising: a second cathode; a second hydroxide mixture inlet coupled to the second hydroxide mixture outlet; a second cathodic gas outlet; and a third hydroxide mixture outlet; a second anodic chamber, comprising: a second anode; a second electrolyte inlet; a second anodic gas outlet; at least one secondary acidic anolyte outlet; a second membrane disposed between the second cathodic chamber and the second anodic chamber; a second hydroxide isolation chamber, comprising: a third hydroxide mixture inlet coupled to the third hydroxide mixture outlet; a second hydroxide collection outlet; and a fourth hydroxide mixture outlet; wherein the second cathodic chamber and the second anodic chamber are in ionic communication.

[0050] In certain embodiments, the at least one secondary acidic anolyte outlet is configured to separate a second acidic anolyte from the second anodic chamber into a third acidic anolyte portion and fourth acidic anolyte portion. In certain embodiments, the second anodic chamber comprises a first secondary acidic anolyte outlet and a second secondary acidic anolyte outlet, and the first secondary acidic anolyte outlet is coupled to the acidic anolyte inlet of the dissolution chamber. In certain embodiments, the first secondary acidic anolyte outlet is configured to provide the third acidic anolyte portion to the dissolution chamber. In certain embodiments, the second secondary acidic anolyte outlet is configured to discharge the fourth acidic anolyte portion. In certain embodiments, the second anodic chamber comprises one secondary acidic anolyte outlet. In certain embodiments, the one secondary acidic anolyte outlet further comprises a first secondary acidic anolyte portion outlet and a second secondary acidic anolyte portion outlet, wherein the first secondary acidic anolyte portion outlet is coupled Atty. Docket No.: UCH-40925

[0051] UCLA Ref. No.: [UCLA 2024-285-1] WO to the acidic anolyte inlet of the dissolution chamber. In certain embodiments, the first secondary portion outlet is configured to provide the third portion of the acidic anolyte to the dissolution chamber. In certain embodiments, the second secondary portion outlet is configured to discharge the second portion of the acidic anolyte.

[0052] In certain embodiments, the system further comprises a device coupled to the at least one secondary acidic anolyte outlet and configured to the adjust a ratio of the third acidic anolyte portion to the fourth acidic anolyte portion. In certain embodiments, the second hydroxide isolation chamber is configured to separate Ca(OH)2 and / or Mg(0H)2 from the first hydroxide mixture.

[0053] In certain embodiments, the system further comprises a CO2 capture chamber. In certain such embodiments, the CO2 capture chamber comprises: a CO2 stream inlet coupled to the gas outlet of the dissolution chamber; a third hydroxide mixture inlet coupled to the second hydroxide mixture outlet of the first electrochemical cell or, when present, the fourth hydroxide mixture outlet of the second electrochemical cell; a stripping gas outlet; and a carbonate product outlet. In certain embodiments, the dissolution chamber comprises the stripping gas inlet, and the stripping gas outlet of the CO2 capture chamber is coupled to the stripping gas inlet of the dissolution chamber. In certain embodiments, the CO2 capture chamber is configured to remove CO2 from a fluid comprising CO2. In some embodiments, the dissolution chamber is configured to convert an acid and a carbonate source into a mixture comprising one or more target ions, a conjugate base of the acid, water, and CO2. In certain embodiments, the mixture comprises one or more target ions comprises Mg2+, Ca2+, or a combination thereof. In certain embodiments, the mixture comprises one or more target ions comprising Mg2+. In certain embodiments, the mixture comprises one or more target ions comprising Ca2+. In certain embodiments, the mixture comprises one or more target ions comprising Mg2+and Ca2+.

[0054] In certain embodiments, the first membrane and, when present, the second membrane comprise: a cation exchange membrane (CEM, e.g., sulfonated tetrafluoroethylene-based fluoropolymer-copolymer), anion exchange membrane (AEM), a non-selective barrier material, or a combination thereof. In certain embodiments, the first membrane and, when present, the second membrane are selective for the passage of Na+ions from the anodic chamber to the cathodic chamber.

[0055] In certain embodiments, the system further comprises a dechlorination chamber, comprising: an anodic gas inlet coupled to the anodic gas outlet of the anodic chamber; a dechlorinating agent; and a dechlorinated gas outlet; wherein the dechlorinating agent is Atty. Docket No.: UCH-40925

[0056] UCLA Ref. No.: [UCLA 2024-285-1] WO configured to reduce CL to CL ions. In certain such embodiments, the first anode and, when present, the second anode are oxygen-selective anodes. In certain embodiments, the first anode and, when present, the second anode, are in the form of a plate. In certain alternative embodiments, the first anode and, when present, the second anode, are in the form of a mesh. In various embodiments, the first cathode and, when present, the second cathode, comprise iron, iron alloy, nickel, nickel alloy, cobalt, cobalt alloy, titanium, titanium alloy, aluminum, aluminum alloy, platinum, or a combination thereof. In various embodiments, the first cathode and, when present, the second cathode, further comprise a coating comprising platinum, nickel phosphate, or molybdenum sulfate. In certain embodiments, the first cathode and, when present, the second cathode, are in the form of a mesh, plate, or rod. In certain such embodiments, the first cathode and, when present, the second cathode, are in the form of a mesh, e.g., a mesh comprising Pt and Ti. Alternatively, the first cathode and, when present, the second cathode, may be in the form of a mesh comprising stainless steel e.g., a 316 stainless steel mesh). In certain embodiments, the first cathode and, when present, the second cathode, are plates, e.g., plates comprising Ti having a coating comprising Pt. Alternatively, the first cathode and, when present, the second cathode, may be plates comprising Ni. In various embodiments, the first anode and, when present, the second anode, comprise a group VIII metal, a group IX metal, a group X metal, titanium clad with a group VIII metal, titanium clad with a group IX metal, titanium clad with a group X metal, titanium clad with mixed metal oxide, or a combination thereof. In certain particular embodiments, the first anode and, when present, the second anode, further comprise iridium, tin, cobalt, manganese, tantalum, ruthenium, graphite, graphene, or carbon nanotube(s).

[0057] In certain embodiments, the first electrochemical cell and, when present, the second electrochemical cell, are configured to produce an anodic gas comprising O2 at the first anode and, when present, the second anode. In certain such embodiments, the anodic gas further comprises Ch. In certain embodiments, the first electrochemical cell and, when present, the second electrochemical cell, are configured to produce a cathodic gas comprising H2 at the first cathode and, when present, the second cathode. In certain embodiments, the first electrochemical cell and, when present, the second electrochemical cell, are configured to produce hydroxides of one or more target ions at the first cathode and, when present, the second cathode. In certain embodiments, the first electrochemical cell is configured to produce Ca(OH)2 and Mg(OH)2 at the first cathode. In certain alternative embodiments, the first electrochemical cell is configured to produce Ca(OH)2 at the first cathode and Mg(OH)2 at the Atty. Docket No.: UCH-40925

[0058] UCLA Ref. No.: [UCLA 2024-285-1] WO second cathode. In yet other embodiments, the first electrochemical cell is configured to produce Mg(OH)2 at the first cathode and Ca(OH)2 at the second cathode. In certain embodiments, the first electrochemical cell is configured to produce Mg(OH)2 at the first cathode. In certain embodiments, the first electrochemical cell is configured to produce Ca(OH)2 at the first cathode.

[0059] In certain embodiments, the first hydroxide isolation chamber is configured to separate a hydroxide of a first target ion from a first hydroxide mixture comprising the hydroxide of the first target ion and a hydroxide of a non-target ion, thereby forming a second hydroxide mixture comprising the hydroxide of the non-target ion. In certain embodiments, the hydroxide of the first target ion is Mg(OH)2. In alternative embodiments, the hydroxide of the first target ion is Ca(OH)2. In certain embodiments, the second hydroxide mixture further comprises a hydroxide of a second target ion; the second hydroxide isolation chamber is present and is configured to separate the hydroxide of the second target ion from the second hydroxide mixture, thereby forming a third hydroxide mixture comprising the hydroxide of the non-target ion. In certain embodiments, the hydroxide of the second target ion is Mg(OH)2. In alternative embodiments, the hydroxide of the second target ion is Ca(OH)2. In certain embodiments, the first hydroxide mixture comprises sodium hydroxide, magnesium hydroxide, or a combination thereof. In certain embodiments, the system is configured to produce calcium hydroxide. In other embodiments, the system is configured to produce magnesium hydroxide. In certain embodiments, the system is configured to produce magnesium hydroxide and calcium hydroxide.

[0060] In certain embodiments, when Mg-concentration is high it may be of economic value to use two sequential electrolyzers to reduce recycle pumping power consumption, while with low Mg concentrations it might be more economical to provide OH' via a recycle rather than using capital intensive electrolyzer hardware. Thus, one of skill in the art would be able to adapt the disclosed systems and methods based on Mg2+concentration to select a suitable configuration for any constraints of dimension or economy.

[0061] In certain embodiments, the dissolution chamber comprises a component configured to stimulate dissolution using acoustic or electric stimulation. Suitable components and techniques for use in the systems and methods disclosed herein are described in, e.g., J. Phys. Chem. C 2020, 124, 30, 16515-16523 and J. Phys. Chem. C 2018, 122, 50, 28665-28673.

[0062] In certain embodiments, the second acidic anolyte portion is discharged. As used herein, the term “discharge” does not necessarily preclude the presence of additional downstream Atty. Docket No.: UCH-40925

[0063] UCLA Ref. No.: [UCLA 2024-285-1] WO system components or method steps involving the second acidic anolyte portion. For example, as will be appreciated by one of skill in the art, the second portion of the acidic anolyte may be neutralized at or after the point of generation, or used in downstream applications where acidic solutions are useful (e.g., as a disinfectant or sterilizing solution).

[0064] In certain aspects, disclosed herein is a method of preparing a hydroxide of at least one target ion is provided, comprising: providing a first electrolyte solution comprising a non-target cation to a first anodic chamber of a first electrochemical cell, the first electrochemical cell further comprising: a first anode disposed within the first anodic chamber; a first cathodic chamber, comprising a first cathode; and a first membrane disposed between and configured to separate the first cathodic chamber and the first anodic chamber; wherein the first anodic chamber and the first cathodic chamber are in fluid communication; performing a first electrochemical process, comprising: applying a first voltage to the first cathode and the first anode; thereby producing: a first acidic anolyte and an anodic gas at the first anode; and a first hydroxide mixture and a cathodic gas at the first cathode; wherein the first acidic anolyte comprises an acid, and the first hydroxide mixture comprises a first hydroxide of at least one target ion and a hydroxide of the nontarget ion; separating the first acidic anolyte into a first portion and a second portion; contacting the first portion of the first acidic anolyte with a source of the at least one target ion , thereby producing a CO2 stream and a target ion stream comprising the at least one target ion, wherein the CO2 stream comprises CO2; providing the target ion stream to the first cathodic chamber; and separating the first hydroxide of the at least one target ion from the first hydroxide mixture, thereby producing a second hydroxide mixture comprising the hydroxide of the nontarget ion.

[0065] In certain embodiments, a method of preparing a hydroxide of at least one target ion is provided, comprising: providing a first electrolyte solution comprising a non-target cation to a first anodic chamber of a first electrochemical cell, the first electrochemical cell further comprising: a first anode disposed within the first anodic chamber; a first cathodic chamber, Atty. Docket No.: UCH-40925

[0066] UCLA Ref. No.: [UCLA 2024-285-1] WO comprising a first cathode; and a first membrane disposed between and configured to separate the first cathodic chamber and the first anodic chamber; wherein the first anodic chamber and the first cathodic chamber are in fluid communication; performing a first electrochemical process, comprising: applying a first voltage to the first cathode and the first anode; thereby producing: a first acidic anolyte and an anodic gas at the first anode; and a first hydroxide mixture and a cathodic gas at the first cathode; wherein the first acidic anolyte comprises an acid, and the first hydroxide mixture comprises a first hydroxide of at least one target ion and a hydroxide of the non-target ion; separating the first acidic anolyte into a first portion and a second portion; contacting the first portion of the first acidic anolyte with a source of the at least one target ion thereby producing a CO2 stream and a target ion stream comprising the at least one target ion, wherein the CO2 stream comprises CO2; providing the target ion stream to the first cathodic chamber; and separating the first hydroxide of the at least one target ion from the first hydroxide mixture, thereby producing a second hydroxide mixture comprising the hydroxide of the non-target ion.

[0067] In certain embodiments, the at least one target ion is one target ion. In other embodiments, the at least one target ion is a first target ion and a second target ion. In certain embodiments, the second hydroxide mixture further comprises a hydroxide of the second target ion, and the method further comprises: separating the hydroxide of the second target ion from the second hydroxide mixture, thereby producing a third hydroxide mixture. In certain embodiments, the method further comprises contacting the target ion stream with the second hydroxide mixture and providing the third hydroxide mixture to the first cathodic chamber.

[0068] In certain embodiments, the method further comprises: providing a second electrolyte solution comprising a non-target cation to a second anodic chamber of a second electrochemical cell, the second electrochemical cell further comprising: a second anode disposed within the second anodic chamber; a second cathodic chamber, comprising a second cathode; and a second membrane disposed between and configured to separate the second cathodic chamber and the second anodic chamber; wherein the second anodic chamber and the second cathodic chamber are in fluid communication; providing the second hydroxide mixture, which further comprises a second target ion to the second cathodic chamber; performing a second electrochemical process, comprising: applying a second voltage to the second cathode and the second anode; thereby producing: a second acidic anolyte and the anodic gas at the second anode; and a third hydroxide mixture and the cathodic gas at the second cathode; wherein the second acidic anolyte comprises an acid, the second hydroxide mixture comprises Atty. Docket No.: UCH-40925

[0069] UCLA Ref. No.: [UCLA 2024-285-1] WO a second target ion and the hydroxide of the non-target ion, and the third hydroxide mixture comprises a hydroxide of the second target ion and the hydroxide of the non-target ion; and separating the hydroxide of the second target ion from the third hydroxide mixture, thereby producing a fourth hydroxide mixture comprising the hydroxide of the non-target ion.

[0070] In certain embodiments, the method further comprises: separating the second acidic anolyte into a third portion and a fourth portion; contacting the third portion of the acidic anolyte with a source of the at least one target ion, thereby producing the CO2 stream and the target ion stream comprising the at least one target ion.

[0071] In certain embodiments, contacting the first portion of the first acidic anolyte with a source of the at least one target ion further comprises contacting the first acidic anolyte and the source of the at least one target ion with a stripping gas. In certain embodiments, the CO2 stream comprises the stripping gas and CO2. In certain embodiments, the method further comprises removing CO2 from the CO2 stream. In certain such embodiments, removing CO2 from the CO2 stream comprises contacting the CO2 stream with the second hydroxide mixture, or, when present, the fourth hydroxide mixture, thereby producing a carbonate of the non-target ion and, when present, the stripping gas.

[0072] In certain embodiments, the carbonate of the non-target ion comprises Na2COs, NaHCCh, or a combination thereof. In certain embodiments, the non-target ion is Na+. In certain embodiments, the first electrolyte solution and, when present, the second electrolyte solution comprise NaCl.

[0073] In certain embodiments, the first acidic anolyte and, when present, the second acidic anolyte comprise HC1. In certain embodiments, the acid comprises H+, H3CL, or a combination thereof.

[0074] In certain embodiments, the stripping gas comprises air. In certain embodiments, the stripping gas comprises less CO2 than ambient air, optionally less than about 1 atm CO2, or preferably less than about 0.01 atm CO2. In certain embodiments, the stripping gas is essentially free of CO2. In certain embodiments, the target ion stream further comprises a conjugate base of the acid. In certain embodiments, the target ion stream comprises CaCh.

[0075] In certain embodiments, the first membrane is selective for the passage of the non-target ion from the first anodic chamber to the first cathodic chamber, and, when present, the second membrane is selective for the passage of the non-target ion from the second anodic chamber to the second cathodic chamber. In certain embodiments, the first membrane is selective for the passage of Na+from the first anodic chamber to the first cathodic chamber, and, when present Atty. Docket No.: UCH-40925

[0076] UCLA Ref. No.: [UCLA 2024-285-1] WO the second membrane is selective for the passage of Na+from the second anodic chamber to the second cathodic chamber. In certain embodiments, the membrane comprises a cation exchange membrane (CEM, e.g, a sulfonated tetrafluoroethylene-based fluoropolymercopolymer), anion exchange membrane (AEM), a non-selective barrier material, or a combination thereof.

[0077] In certain embodiments, the cathodic gas comprises EE.

[0078] In certain embodiments, the anodic gas comprises O2.

[0079] In certain embodiments, the method further comprises dechlorinating the anodic gas. In certain such embodiments, dechlorinating the anodic gas comprises contacting the anodic gas with a dechlorinating agent, thereby reducing Ch to CL ions and producing a dechlorinated gas comprising O2. The dechlorinating agent may comprise, for example, magnesium, calcium, a sorbent comprising carbon (e.g., activated carbon), or an alkaline material (e.g., a solid comprising an alkaline material or a solution comprising an alkaline material). In certain embodiments, the dechlorinating agent is or is derived from the second hydroxide mixture, the fourth hydroxide mixture, when present, or a combination thereof.

[0080] In certain embodiments, the first anode and, when present, the second anode are oxygen-selective anodes.

[0081] In certain such embodiments, the first cathode and, when present, the second cathode comprise iron, iron alloy, nickel, nickel alloy, titanium, titanium alloy, aluminum, aluminum alloy, platinum, or a combination thereof. In certain preferred embodiments, the first cathode and, when present, the second cathode further comprise a coating comprising platinum, nickel phosphate, or molybdenum sulfate. In various embodiments, the first cathode and, when present, the second cathode are in the form of a mesh, plate, or rod. In certain such embodiments, the first cathode and, when present, the second cathode are in the form of a mesh, e.g., a mesh comprising Pt and Ti. In certain embodiments, the first cathode and, when present, the second cathode are in the form of a mesh comprising stainless steel (e.g, a 316 stainless steel mesh). In certain embodiments, the first cathode and, when present, the second cathode are in the form of a plate, e.g., a plate comprising Ti having a coating comprising Pt. In certain embodiments, the first cathode and, when present, the second cathode are in the form of a plate comprising Ni.

[0082] In certain embodiments, the first anode and, when present, the second anode comprise a group VIII metal, a group IX metal, a group X metal, titanium clad with a group VIII metal, titanium clad with a group IX metal, titanium clad with a group X metal, titanium clad with Atty. Docket No.: UCH-40925

[0083] UCLA Ref. No.: [UCLA 2024-285-1] WO mixed metal oxide, or a combination thereof. In certain preferred embodiments, the first anode and, when present, the second anode further comprise iridium, tin, cobalt, manganese, tantalum, ruthenium, graphite, graphene, or carbon nanotube(s).

[0084] In certain embodiments, separating the hydroxide of the at least one target ion from the first hydroxide mixture comprises filtering the first hydroxide mixture. In certain embodiments, separating the hydroxide of the at least one target ion from the first hydroxide mixture comprises clarifying the first hydroxide mixture. In certain embodiments, separating the hydroxide of the at least one target ion from the first hydroxide mixture comprises sedimentation of the first hydroxide mixture. In certain embodiments, separating the hydroxide of the second target ion from the third hydroxide mixture comprises filtering the third hydroxide mixture. In certain embodiments, separating the hydroxide of the second target ion from the third hydroxide mixture comprises clarifying the third hydroxide mixture. In certain embodiments, separating the hydroxide of the second target ion from the third hydroxide mixture comprises sedimentation of the third hydroxide mixture.

[0085] In certain embodiments, the method further comprises discharging the second portion of the acidic anolyte. In certain embodiments, the method further comprises neutralizing the second portion of the acidic anolyte.

[0086] In certain embodiments, the split ratio (defined as the ratio of the first portion to the second portion (discharge)) is from about 1 :9 to about 9: 1. In further embodiments, the split ratio is from about 1 :3 to about 5: 1. In yet further embodiments, the split ratio is about 1 : 1, to about 3: 1, ,or about 2: 1. In certain embodiments, the split ratio is about 0.5:99.5. In certain preferred embodiments, the split ratio is about 2: 1.

[0087] In certain preferred embodiments, about 33-40% of the volume of the acidic anolyte is discharged. In certain embodiments, discharging greater than about 40% would allow for additional CO2 capture (e.g., from air), while discharging less than about 33% would lead to some CO2 emissions.

[0088] In certain embodiments, the method has a gross Electrical Energy Intensity (gEEI) of less than about 5 MW / MT(Ca(0H)2). In further embodiments, the method has an gEEI of less than about 4 MW / MT(Ca(0H)2). In certain embodiments, the method has an gEEI of about 3 MW / MT(Ca(0H)2). In certain embodiments, a system operating at approximately thermodynamic conditions has a gEEI of ~2 MW / MT(Ca(0H)2).

[0089] In certain embodiments, as will be appreciated by one of ordinary skill in the art, separating the hydroxide of the at least one target ion from the first hydroxide mixture Atty. Docket No.: UCH-40925

[0090] UCLA Ref. No.: [UCLA 2024-285-1] WO comprises precipitating the hydroxide of the at least one target ion. Said precipitation may occur optionally within the cathodic chamber (e.g., resulting in a suspension of the hydroxide of the at least one target ion within the cathodic chamber) or outside of the cathodic chamber (e.g., in a hydroxide isolation chamber or precipitation chamber fluidly coupled to an outlet of the cathodic chamber).

[0091] Definitions

[0092] Unless otherwise defined herein, scientific and technical terms used in this application shall have the meanings that are commonly understood by those of ordinary skill in the art. Generally, nomenclature used in connection with, and techniques of, chemistry, chemical engineering, electrical engineering and civil engineering described herein, are those well- known and commonly used in the art.

[0093] The methods and techniques of the present disclosure are generally performed, unless otherwise indicated, according to conventional methods well known in the art and as described in various general and more specific references that are cited and discussed throughout this specification.

[0094] Chemistry terms used herein, unless otherwise defined herein, are used according to conventional usage in the art, as exemplified by “The McGraw-Hill Dictionary of Chemical Terms”, Parker S., Ed., McGraw-Hill, San Francisco, C.A. (1985).

[0095] All publications, patents and published patent applications referred to in this application are specifically incorporated by reference herein. In case of conflict, the present specification, including its specific definitions, will control.

[0096] As used herein, the term “particle size” refers to the mean particle size (dso) as determined through, e.g., dynamic light scattering.

[0097] As used herein, the term “production capacity” refers to the upper boundary of the dry mass of pure product equivalents that may be produced per unit of time.

[0098] As used herein, the term “spent solution" refers to the residual solution utilized in a prior step of a process (e.g., nanofiltration or electrolysis) which may optionally be re-used or discarded depending on the user’s needs and the configuration of the system.

[0099] As used herein the term gEEI refers to gross Electrical Energy Intensity, which is a measure of the total electrical energy required by a process to produce a given amount of a product [e.g., a metric tonne (MT) of Ca(OH)2]. gEEI values referred to in the present disclosure are calculated according to the formula: gEEI = [(current applied) (voltage)] / (mass Atty. Docket No.: UCH-40925

[0100] UCLA Ref. No.: [UCLA 2024-285-1] WO of Ca(OH)2 produced), which also includes the production of any co-products such as H2. In methods of the present disclosure, the value of the electric potential (voltage) applied to the cathode and anode in the electrochemical positively correlates with the gEEI of the process. For example, a process having a gEEI of about 4 MWh / MTCa(0H)2 would be considered more energy efficient than a process having a gEEI of 5 MWh / MTCa(0H)2 by one of skill in the art.

[0101] As used herein, the term “hydrodynamic separation” refers to the physical separation of two fluid feed streams or processes that are usually or may be combined. For example, the term may refer to, e.g., separation of an anolyte from a catholyte stream in an electrochemical process. The term “hydrodynamic separation” may also be used herein to refer to the separation of an electrolysis chamber (e.g., where H+and OH' ions are produced from aqueous solutions) and a precipitation chamber (e.g., where an aqueous ionic species comprising the OH' ions is precipitated from solution) such that the precipitation of the hydroxide species occurs in the precipitation chamber instead of in the electrolysis chamber.

[0102] As used herein, the term “interelectrode distance” refers to the magnitude of the minimum distance between an outer face of a first conductive element and an outer face of a second electrically conductive element.

[0103] The term “target ion,” as used herein, refers to an ion that is desired or “targeted” for concentration, preparation, and / or isolation by the systems and methods disclosed herein. For example, the systems and methods of the disclosure may favor the separation, concentration, and production of compounds comprising Ca2+(an exemplary target ion) from mixtures comprising Ca2+and at least one additional “non-target” ion. Additionally, as will be appreciated by one of skill in the art, the use of the term “target” to modify other terms such as “mixture” and “precipitate” signifies that the mixture or precipitate comprises target ion(s). In systems of the disclosure configured to produce multiple hydroxide products, there may be multiple target ions, e.g., a first target ion and a second target ion. For example, in a system configured to produce Mg(0H)2 and Ca(OH)2, Mg2+and Ca2+are both target ions.

[0104] The term “non-target ion,” as used herein, refers to an ion that is not desired or targeted for concentration, preparation, and / or isolation by the systems and methods disclosed herein. For example, non-target ions involved in the systems and methods disclosed herein may be selected from Fe2+, and Na+, and combinations thereof. For example, systems and methods of the disclosure may involve the separation and concentration of hydroxides comprising Ca2+(a target ion) from mixtures comprising Ca2+and at least one additional “non-target” ion, such as Fe2+, and Na+. Atty. Docket No.: UCH-40925

[0105] UCLA Ref. No.: [UCLA 2024-285-1] WO

[0106] The term “stripping gas” as used herein refers to a fluid (preferably a gaseous fluid) that may be present in the dissolution chamber when contacting an acid (e.g., a portion of the acidic anolyte) with a carbonate source (e.g., CaCOs), thereby producing CO2 and a solution comprising the target ion (e.g., Ca2+). The stripping gas may aid the decarbonation of the carbonate source by facilitating or assisting in the removal of CO2 from the dissolution chamber, thereby affecting decarbonation equilibria in favor of the products e.g. CO2 and aqueous target ions). As a non-limiting example, the stripping gas may be air, or air that is substantially free of CO2 (e.g, the gas produced by a CO2 capture process), or any other gas low in or free of CO2, e.g, the anodic gas, cathodic gas or a mixture of anodic and cathodic gases.

[0107] The terms “anodic gas” and “cathodic gas” as used herein refer to gaseous products that are produced at the anode and cathode, respectively. For example, an anodic gas may comprise O2, and a cathodic gas may comprise H2.

[0108] The term “source” as used herein in connection with chemical elements (e.g., calcium) refers to a composition that comprises the element.

[0109] INCORPORATION BY REFERENCE

[0110] All publications and patents mentioned herein are hereby incorporated by reference in their entirety as if each individual publication or patent was specifically and individually indicated to be incorporated by reference. In case of conflict, the present application, including any definitions herein, will control.

[0111] EQUIVALENTS

[0112] While specific embodiments of the subject invention have been discussed, the above specification is illustrative and not restrictive. Many variations of the invention will become apparent to those skilled in the art upon review of this specification and the claims below. The full scope of the invention should be determined by reference to the claims, along with their full scope of equivalents, and the specification, along with such variations.

[0113] EXAMPLES

[0114] The production of Ordinary Portland Cement (OPC) clinker, in accordance with the systems and processes described herein (e.g., Fig. 1), involves calcining a mixture of limestone, clay and quartz at high temperatures (~1450°C). This process emits CO2 from two sources: (1) a primary source (-60% of emissions): the thermal decomposition of limestone (CaCOs), and (2) a secondary source (-40% of emissions): the combustion of fossil fuels to generate process Atty. Docket No.: UCH-40925

[0115] UCLA Ref. No.: [UCLA 2024-285-1] WO heat. At contemporary scale of OPC production, ~4.5 billion tonnes, together, these emissions result in -10% of global CO2 emissions. The process described herein electrolytically produces calcium hydroxide (Ca(OH)2; a cement precursor) and hydrogen (H2(g)) using limestone, alkaline rock (and / or industrial wastes), saline water, and electricity as feedstocks while nearly eliminating CO2 emissions. The approach effectively eliminates primary OPC emissions (>95% reduction), and fuel-related, secondary emissions (-90% reduction with the utilization of coproduced H2). The process involves a series of steps organized into a continuous flow process that operates at ambient pressure and temperature.

[0116] These steps include:

[0117] (1) dissolution of limestone

[0118] (2) separation of dissolved CO2 from the calcium-rich solution

[0119] (3) precipitation of Ca(OH)2 from the calcium-rich solution using electrochemically produced alkalinity

[0120] (4) fixation of the separated CO2 as bicarbonate anions (HCO3 ) in water

[0121] (5) neutralization of the (electrochemically) co-produced acid.

[0122] The process description considers stoichiometric feedstocks. Limestone is represented as CaCCh and the electrolyte is represented as a NaCl solution with a concentration equivalent to seawater (-0.5 mol / L). In this process, seawater is fed into a flow electrolyzer operating at ambient pressure and temperature. The electrolyzer is fitted with a platinum-coated titanium cathode, and oxygen selective anodes (OSAs). This configuration of an acid-base electrolyzer produces alkalinity (OH ) and hydrogen (H2(g)) at the cathode, and acidity (H+) and oxygen (02(g)), and a trivial quantity of chlorine at the anode. Based on operational data, these OSAs are >99% selective towards O2(g) evolution by suppressing the kinetically more favorable Cl2(g) evolution. The residual chlorine evolved was removed by absorption using an alkaline solution, or a high-surface area solid (e.g., biochar). For simplicity, inferring 100% oxygen selectivity, the anode half-reaction can be written per Equation (la), while the cathode reaction is written in Equation (lb). Atty. Docket No.: UCH-40925

[0123] UCLA Ref. No.: [UCLA 2024-285-1] WO

[0124] The acidic anolyte (~pH 1) made up of of H2O, NaCl and HC1, formed within the anode compartment of the electrolyzer is split and the unused portion (~33 mass %, 27 kgHci(i) / kgca(OH)2(s)) is neutralized by bringing it in contact with alkaline minerals within a stirred tank reactor (e.g., granulated basalt rocks, or steel slag [dso-l-to-5 mm] which are readily and abundantly available around the world), and thereafter prepared for effluent discharge at pH~8.2 i.e., prevailing oceanic pH). The remainder of the acid (~67 mass %) is used for CaCOs dissolution. The dissolution of finely granulated CaCOs (dso<5O pm, i.e., similar to cement kiln feed) in an acidic environment is written in Equation (2).

[0125] Upon the dissolution of CaCCL, CC g) is evolved. Stripping (flowing) air was introduced into the dissolution reaction, to hasten CO2 removal and limestone’s dissolution kinetics. If such stripping is not carried out, the dissolution kinetics would be degraded according to Le Chatelier’s principle caused by CO2 enrichment in the gas-phase in the reactor. The solubility of CaCCL in solution is a function of the pH. The CC g) evolved herein is directed into a “absorber” containing electrochemically produced alkalinity (NaOH) where it is rendered into aqueous HCCU anionic species by an acid-base neutralization reaction. The spent catholyte exiting the absorber features a pH of ~8.2 (i.e., typical oceanic pH), ensuring that all the effluent streams, (i.e., the catholyte and anolyte) feature no pH change (ApH~0) from the point of entry to the point of discharge of the process.

[0126] After (CaCCL) dissolution and (CO2) stripping, the solution containing solubilized calcium features a pH of ~5-6. The highest pH and the highest quantity of dissolved calcium may be preferable; however, such conditions may be contradictory as Ca-solubility diminishes with increasing pH. The Ca-containing (~0.1 mol / Lca), and the nearly CCL-free solution is fed into the cathode compartment of the electrolyzer where it is alkalinized. This results in the instantaneous precipitation of Ca(OH)2 at pH>12.5 at near-stoichiometric yield. The alkaline precipitate contained in the suspension is filtered after it exits the reactor to remove the solids. The Ca(OH)2 precipitation reaction is written in Equation (3).

[0127] The remaining alkaline catholyte solution (pH~13) flows into the absorber column where it recaptures CO2 entrained in the stripping air (~15 vol. %), evolved during CaCCL dissolution. The CO2 capture reaction is shown in Equation (4). The speciation of CO2 in alkaline solutions (pH >7) is pH-dependent, resulting in partitioning such that while carbonate Atty. Docket No.: UCH-40925

[0128] UCLA Ref. No.: [UCLA 2024-285-1] WO

[0129] (CO32; and hence Na2COs) is dominant in pH >10.3 solutions, bicarbonate (HCOs', and hence NaHCOs) is dominant in pH<10.3 solutions. In both cases, carbonate anions are charge compensated by Na-species in solution. Since HCOs' offers more “mole-efficient” CO2-storage, the absorber column’s mass flow rates of solution and gas are designed to yield pH 8.2 at the outlet which implies a solution that is dominant in HCCU species.

[0130] The overall water splitting, and acid-base generation reactions in the electrolyzer are described as written in Equation (5).

[0131] The overall reaction of operations excluding the electrolyzer and acid neutralization is expressed in Equation (6):

[0132] The overall reaction of the process is then written as per Equation (7), with Fig. 6 showing a Process Flow Diagram (PFD) of the overall mass flows.

[0133] The energy intensity of the exemplary process can be established thermodynamically, by analysis of the Gibbs free energy (ideal work) of reaction(s). The Gibbs free energies can be compared to realistic process aspects to establish the practical energy demands of the process, and the reasonableness of the estimates. In general, the larger the Gibbs free energy, the more energy required for the reaction to proceed. The Gibbs free energy of each process step (see Equations (2-5) are shown in Table 1. The Gibbs free energies of limestone dissolution, Ca(OH)2 precipitation, and CO2 capture are negative, indicating spontaneous downhill “exergonic” reactions. Conversely, the electrolysis step features a positive Gibbs free energy, implying an endergonic reaction that requires the input of electricity to proceed. This implies that overall reaction of operations are thermodynamically favorable and do not require extrinsic energy (i.e., other than pumping, stirring and sensors and control systems). As such, the energy intensity of the process largely depends on the efficiency of acid-base generation within the electrolyzer, and the utilization efficiency of the OH anions produced in the process. Atty. Docket No.: UCH-40925

[0134] UCLA Ref. No.: [UCLA 2024-285-1] WO

[0135] Table 1: A tabulation of the Gibbs free energy (AG) for each reaction step (i.e., unit operation) of the process. For convenience, 1 kJ / moleca = 0.00375 MWh / tca(OH)2.

[0136] The thermodynamic voltage (i.e., potential difference from the anode to the cathode) of acid-base electrolysis is -2.06 V at standard conditions, which can be derived from the Gibbs free energy change of the overall reaction in the electrolyzer, Equation (8):

[0137] AG

[0138] E = - - (8) nF where, AG is Gibbs free energy change per mole of reaction (kJ), n is number of moles of electrons transferred in the reaction, F is Faraday constant (C / mol) and E is the cell potential (V). Inferring the stoichiometric conversion of all the calcium contained in the catholyte effluent to Ca(OH)2, a thermodynamic voltage of -2.06 V implies a gross Energy Intensity (gEI) of 2.24 MWh / tca(OH)2 for electrolysis only, including the energy required for the co-production of hydrogen. Practically, the equipment used will require no more than ~5% of the electrolysis energy demand, confirmed through experimentation. Since 40.8 kg of E g) are produced (see Equation lb) per tonne of Ca(OH)2, the net Energy Intensity (nEI) of Ca(OH)2 production in this scenario is 0.27 MWh / tca(OH)2. Significantly, the co-produced hydrogen is assumed to embody 51 kWh / kgH2, which is the energy required to produce hydrogen via comtemporary PEM [Proton Exchange Membrane] electrolysis methods.

[0139] The example described herein considers “ideal” (thermodynamic minimum) considerations, (e.g., E = -2.06 V and stoichiometric conversion, i.e., a Faradaic efficiency of OH generation (FE) of 100%). These conditions are potentially unsustainable over extended operations. To establish a practical energy intensity estimate, data based on seawater flow electrolyzers, fitted with cathodes and anodes, was used. Said electrolyzers were designed for electrochemical mineral precipitation as described in WO 2025072412 Al, the contents of which is hereby incorporated by reference in its entirety. By using actual seawater, said electrolyzers achieve a Faradaic efficiency of 80-to-90% when fitted with conventional cation exchange membranes (OEMs). The membranes separate the acidic anolyte and alkaline catholyte thereby reducing acid-base neutralization within the electrolyzer while allowing cation (and hence, ion current) transport across the membrane. Second, a thermodynamic Atty. Docket No.: UCH-40925

[0140] UCLA Ref. No.: [UCLA 2024-285-1] WO voltage of -2.06 V implies an infinitesimal separation between in the anode and the cathode and infinitely slow reaction rates. Said electrolyzers were hydrodynamically and electrochemically optimized for mineral precipitation in a seawater electrolyte feature an electrode-to-electrode separation of ~3 mm. In this “gap” - ionic current conduction is limited by the thickness and the concentration of the electrolyte. The electrolyzers are operate at E ~ - 3.0 V, with the cell voltage in the midst of being progressively diminished to -2.8 V as the electrolyzers undergo design and operational optimization. When analyzed using Equations (7- 8), these inputs imply a nEI (gEI) of 1.06 (3.38) MWh / tca(OH)2 for electrolyzer operations only (see also, Table 2, FE = 90%, Scenario 2). It should be noted that the hydrogen yield is proportional to the Faradaic efficiency. As such, the lower Faradaic efficiency, the higher hydrogen yield.

[0141] Table 2: An overview of the energy intensity for different scenarios of cell voltage and Faradaic efficiency. Scenarios 1 and 2 assume stoichiometric conversions with an overall reaction of operations energy demand of ~5% of the overall energy demand. Scenario 3 assumes FE ~ 90%, and considers the practical energy demands for all unit operations (e.g„ CSTR, CO2 absorber, pumps, etc.) using practical equipment data and precise chemical speciation.

[0142] Estimates of electrolyzer performance data were used within a comprehensive simulation framework that accounts for overall reaction of operations, and additional considerations including:

[0143] (1) CO2 desorption (and absorption) efficiency and Ca(OH)2 product purity. In a real-world process it is not possible to remove / absorb 100% of CO2 from the Ca-containing solution after Atty. Docket No.: UCH-40925

[0144] UCLA Ref. No.: [UCLA 2024-285-1] WO limestone dissolution. Thus, some Ca will reprecipitate as CaCO3instead of Ca(OH)2 (generally <5 mass %).

[0145] (2) Carbonate speciation. In a real-world process, the dissolved CO2 undergoes a series of reactions and exists in a variety of different species depending on pH. Considering said factors, simulation results show a slightly higher nEI (gEI) of 1.17 (3.56) MWh / tca(OH)2, including overall reaction of operations in the energy analysis. Table 3 provides a parametric overview of how the cell voltage, Faradaic efficiency, and BoP operations affect the overall energy intensity.

[0146] In general, it should be noted that the simulations are very well aligned with the chemical / stoichiometric considerations laid out above. For example, Table 3 summarizes the stoichiometric coefficients of the overall reaction for stoichiometric and simulated (real-world) conditions. The overall close agreement indicates that the real-world process operates closely to the (ideal) stochiometric process. Discrepancies may be due to aspects such as CO2 speciation, and absorption / desorption (in)efficiencies, and (real-world) reaction yields being expectedly inferior to purely stoichiometry considerations.

[0147] Table 3: A comparison of the reaction coefficients based on stoichiometric considerations (see Equation 7), and a simulated practical process.

[0148] Ca(OH)2, following precipitation, is filtered and dried (e.g., using cement flue gas which possesses an exhaust temperature of ~400°C) prior to being introduced into a cement production process. Unlike limestone, on account of its lower decomposition temperature (~550°C versus ~800°C for limestone, at 1 bar), Ca(OH)2 would be fully decomposed into CaO (i.e., the primary ingredient required for cement production), within the preheater and precalciner of a cement production process. As such, it would enter the cement kiln fully decomposed in the form of CaO, thereby reducing residence time and improving kiln productivity and throughput. Second, Ca(OH)2 features a lower enthalpy of decomposition (AH) as compared to limestone (108 kJ / mol versus 179 kJ / mol). Thus, a smaller amount of energy is needed for the production of CaO from Ca(OH)2, and the process heat demand and secondary Atty. Docket No.: UCH-40925

[0149] UCLA Ref. No.: [UCLA 2024-285-1] WO emissions of the exemplary process without and while utilizing co-produced hydrogen is -20% and -90% less than conventional processes, respectively.

[0150] Based on available data, the exemplary process features a nEI of -1.17 MWh / tca(OH)2 to produce a zero-carbon lime feedstock for cement production, while co-producing clean hydrogen as a final product or to heat the kiln. The process provides the opportunity to decarbonize several calcium products while enabling permanent CO2 storage including: 1) cement clinker, and 2) hydrated lime (portlandite, Ca(OH)2).

[0151] In another example, the process described herein produces quicklime and and cement clinker at an energy intensity of 1.83 MWh / tciinker while achieving up to 95% process decarbonization. For reference, the traditional production of quicklime and OPC clinker implies an energy demand of -1.4 MWh / tciinker.

[0152] In another example, thermodynamically hydrated lime production is very attractive due to its potential use as a CO2 sorbent, and cementation agent in concrete. Hydrated lime production with full decarbonization can be achieved within the exemplary process at an energy intensity of 1.17 MWh / tca(OH)2, while the co-produced H2 can be collected for other uses. This range of energy intensities is very attractive for fully electrified processes that effectively eliminate all CO2 emissions from conceivably the hardest to abate industrial sectors without requiring carbon capture and (geological) storage (CCS).

Claims

Atty. Docket No.: UCH-40925UCLA Ref. No.: [UCLA 2024-285-1] WOWe claim:

1. A system, comprising: a first electrochemical cell, comprising: a first cathodic chamber, comprising: a first cathode; a target ion stream inlet; a first cathodic gas outlet; and a first hydroxide mixture outlet; a first anodic chamber, comprising: a first anode; a first electrolyte inlet; a first anodic gas outlet; at least one primary acidic anolyte outlet; a first membrane disposed between the first cathodic chamber and the first anodic chamber; a dissolution chamber, comprising: an acidic anolyte inlet coupled to the at least one primary acidic anolyte outlet; a target ion carbonate feed inlet; a gas outlet; and a target ion stream outlet coupled to the target ion stream inlet of the cathodic chamber; and a first hydroxide isolation chamber, comprising: a first hydroxide mixture inlet coupled to the first hydroxide mixture outlet; a first hydroxide collection outlet; and a second hydroxide mixture outlet; wherein the first cathodic chamber and the first anodic chamber are in ionic communication.

2. The system of claim 1, wherein the at least one primary acidic anolyte outlet is configured to separate a first acidic anolyte from the first anodic chamber into a first acidic anolyte portion and second acidic anolyte portion.Atty. Docket No.: UCH-40925UCLA Ref. No.: [UCLA 2024-285-1] WO3. The system of claim 1 or 2, wherein the first anodic chamber comprises a first primary acidic anolyte outlet and a second primary acidic anolyte outlet, and the first primary acidic anolyte outlet is coupled to the acidic anolyte inlet of the dissolution chamber.

4. The system of claim 3, wherein the first primary acidic anolyte outlet is configured to provide the first acidic anolyte portion to the dissolution chamber.

5. The system of claim 3 or 4, wherein the second primary acidic anolyte outlet is configured to discharge the second acidic anolyte portion.

6. The system of claim 1 or 2, wherein the first anodic chamber comprises one primary acidic anolyte outlet.

7. The system of claim 6, wherein the one primary acidic anolyte outlet further comprises a first primary acidic anolyte portion outlet and a second primary acidic anolyte portion outlet, wherein the first primary acidic anolyte portion outlet is coupled to the acidic anolyte inlet of the dissolution chamber.

8. The system of claim 7, wherein the first primary portion outlet is configured to provide the first portion of the acidic anolyte to the dissolution chamber.

9. The system of claim 8, wherein the second primary portion outlet is configured to discharge the second portion of the acidic anolyte.

10. The system of any one of claims 1-9, further comprising a device coupled to the at least one primary acidic anolyte outlet and configured to the adjust a ratio of the first acidic anolyte portion to the second acidic anolyte portion.

11. The system of any one of claims 1-10, wherein the first hydroxide isolation chamber is configured to separate Ca(OH)2 from the first hydroxide mixture.

12. The system of any one of claims 1-10, wherein the first hydroxide isolation chamber is configured to separate Mg(0H)2 from the first hydroxide mixture.Atty. Docket No.: UCH-40925UCLA Ref. No.: [UCLA 2024-285-1] WO13. The system of any one of claims 1-12, further comprising: a second hydroxide isolation chamber, comprising: a second hydroxide mixture inlet coupled to the second hydroxide mixture outlet; a second hydroxide collection outlet; and a third hydroxide mixture outlet.

14. The system of claim 13, further comprising a hydroxide precipitation chamber disposed between the first hydroxide isolation chamber and the second hydroxide isolation chamber, the hydroxide precipitation chamber comprising: a first precipitation chamber inlet coupled to the second hydroxide mixture outlet; a second precipitation chamber inlet coupled to the target ion stream outlet; a precipitation chamber outlet coupled to the second hydroxide mixture inlet of the second hydroxide isolation chamber.

15. The system of any one of claims 1-14, wherein the dissolution chamber further comprises a stripping gas inlet.

16. The system of any one of claims 1-15, wherein the system comprises a single electrochemical cell.

17. The system of any one of claims 1-12 and 15, further comprising: a second electrochemical cell, comprising: a second cathodic chamber, comprising: a second cathode; a second hydroxide mixture inlet coupled to the second hydroxide mixture outlet; a second cathodic gas outlet; and a third hydroxide mixture outlet; a second anodic chamber, comprising: a second anode; a second electrolyte inlet; a second anodic gas outlet;Atty. Docket No.: UCH-40925UCLA Ref. No.: [UCLA 2024-285-1] WO at least one secondary acidic anolyte outlet; a second membrane disposed between the second cathodic chamber and the second anodic chamber; a second hydroxide isolation chamber, comprising: a third hydroxide mixture inlet coupled to the third hydroxide mixture outlet; a second hydroxide collection outlet; and a fourth hydroxide mixture outlet; wherein the second cathodic chamber and the second anodic chamber are in ionic communication.

18. The system of claim 17, wherein the at least one secondary acidic anolyte outlet is configured to separate a second acidic anolyte from the second anodic chamber into a third acidic anolyte portion and fourth acidic anolyte portion.

19. The system of claim 17 or 18, wherein the second anodic chamber comprises a first secondary acidic anolyte outlet and a second secondary acidic anolyte outlet, and the first secondary acidic anolyte outlet is coupled to the acidic anolyte inlet of the dissolution chamber.

20. The system of claim 19, wherein the first secondary acidic anolyte outlet is configured to provide the third acidic anolyte portion to the dissolution chamber.

21. The system of claim 19 or 20, wherein the second secondary acidic anolyte outlet is configured to discharge the fourth acidic anolyte portion.

22. The system of claim 17 or 18, wherein the second anodic chamber comprises one secondary acidic anolyte outlet.

23. The system of claim 22, wherein the one secondary acidic anolyte outlet further comprises a first secondary acidic anolyte portion outlet and a second secondary acidic anolyte portion outlet, wherein the first secondary acidic anolyte portion outlet is coupled to the acidic anolyte inlet of the dissolution chamber.Atty. Docket No.: UCH-40925UCLA Ref. No.: [UCLA 2024-285-1] WO24. The system of claim 23, wherein the first secondary portion outlet is configured to provide the third portion of the acidic anolyte to the dissolution chamber.

25. The system of claim 24, wherein the second secondary portion outlet is configured to discharge the second portion of the acidic anolyte.

26. The system of any one of claims 17-25, further comprising a device coupled to the at least one secondary acidic anolyte outlet and configured to the adjust a ratio of the third acidic anolyte portion to the fourth acidic anolyte portion.

27. The system of any one of claims 17-26, wherein the second hydroxide isolation chamber is configured to separate Ca(OH)2 from the first hydroxide mixture.

28. The system of any one of claims 17-26, wherein the second hydroxide isolation chamber is configured to separate Mg(0H)2 from the first hydroxide mixture.

29. The system of any one of claims 1-28, further comprising a CO2 capture chamber.

30. The system of claim 29, wherein the CO2 capture chamber comprises: a CO2 stream inlet coupled to the gas outlet of the dissolution chamber; a third hydroxide mixture inlet coupled to the second hydroxide mixture outlet of the first electrochemical cell or, when present, the fourth hydroxide mixture outlet of the second electrochemical cell; a a stripping gas outlet; and a carbonate product outlet.

31. The system of claim 30, wherein the dissolution chamber comprises the stripping gas inlet, and the stripping gas outlet of the CO2 capture chamber is coupled to the stripping gas inlet of the dissolution chamber.

32. The system of any one of claims 29-31, wherein the CO2 capture chamber is configured to remove CO2 from a fluid comprising CO2.Atty. Docket No.: UCH-40925UCLA Ref. No.: [UCLA 2024-285-1] WO33. The system of any one of claims 1-32, wherein the dissolution chamber is configured to convert an acid and a carbonate source into a mixture comprising one or more target ions, a conjugate base of the acid, water, and CO2.

34. The system of claim 33, wherein the mixture comprising one or more target ions comprises Mg2+, Ca2+, or a combination thereof.

35. The system of claim 34, wherein the mixture comprising one or more target ions comprises Mg2+.

36. The system of claim 34 or 35, wherein the mixture comprising one or more target ions comprises Ca2+.

37. The system of any one of claims 34-36, wherein the mixture comprising one or more target ions comprises Mg2+and Ca2+.

38. The system of any one of claims 1-37, wherein the first membrane and, when present, the second membrane comprise: a cation exchange membrane (CEM, e.g., sulfonated tetrafluoroethylene based fluoropolymer-copolymer), anion exchange membrane (AEM), a non-selective barrier material, or a combination thereof.

39. The system of any one of claims 1-38, wherein the first membrane and, when present, the second membrane are selective for the passage of Na+ions from the anodic chamber to the cathodic chamber.

40. The system of any one of claims 1-39, further comprising a dechlorination chamber, comprising: an anodic gas inlet coupled to the anodic gas outlet of the anodic chamber; a dechlorinating agent; and a dechlorinated gas outlet; wherein the dechlorinating agent is configured to reduce Ch to CL ions.

41. The system of any one of claims 1-40, wherein the first anode and, when present, the second anode are oxygen-selective anodes.Atty. Docket No.: UCH-40925UCLA Ref. No.: [UCLA 2024-285-1] WO42. The system of any one of claims 1-41, wherein the first anode and, when present, the second anode, are in the form of a plate.

43. The system of any one of claims 1-41, wherein the first anode and, when present, the second anode, are in the form of a mesh.

44. The system of any one of claims 1-43, wherein the first cathode and, when present, the second cathode, comprise iron, iron alloy, nickel, nickel alloy, cobalt, cobalt alloy, titanium, titanium alloy, aluminum, aluminum alloy, platinum, or a combination thereof.

45. The system of any one of claims 1-44, wherein the first cathode and, when present, the second cathode, further comprise a coating comprising platinum, nickel phosphate, or molybdenum sulfate.

46. The system of any one of claims 1-45, wherein the first cathode and, when present, the second cathode, are in the form of a mesh, plate, or rod.

47. The system of any one of claims 1-46, wherein the first cathode and, when present, the second cathode, are in the form of a mesh.

48. The system of any one of claims 1-47, wherein the first cathode and, when present, the second cathode, are mesh comprising Pt and Ti.

49. The system of any one of claims 1-48, wherein the first cathode and, when present, the second cathode, are mesh comprising stainless steel (e.g., a 316 stainless steel mesh).

50. The system of any one of claims 1-46, wherein the first cathode and, when present, the second cathode, are plates.

51. The system of claim 50, wherein the first cathode and, when present, the second cathode, are plates comprising Ti having a coating comprising Pt.

52. The system of claim 50, wherein the first cathode and, when present, the second cathode, are plates comprising Ni.Atty. Docket No.: UCH-40925UCLA Ref. No.: [UCLA 2024-285-1] WO53. The system of any one of claims 1-52, wherein the first anode and, when present, the second anode, comprise a group VIII metal, a group IX metal, a group X metal, titanium clad with a group VIII metal, titanium clad with a group IX metal, titanium clad with a group X metal, titanium clad with mixed metal oxide, or a combination thereof.

54. The system of any one of claims 53, wherein the first anode and, when present, the second anode, further comprise iridium, tin, cobalt, manganese, tantalum, ruthenium, graphite, graphene, or carbon nanotube(s).

55. The system of any one of claims 1-54, wherein the first electrochemical cell and, when present, the second electrochemical cell, are configured to produce an anodic gas comprising O2 at the first anode and, when present, the second anode.

56. The system of claim 55, wherein the anodic gas further comprises Ch.

57. The system of any one of claims 1-56, wherein the first electrochemical cell and, when present, the second electrochemical cell, are configured to produce a cathodic gas comprising H2 at the first cathode and, when present, the second cathode.

58. The system of any one of claims 1-57, wherein the first electrochemical cell and, when present, the second electrochemical cell, are configured to produce hydroxides of one or more target ions at the first cathode and, when present, the second cathode.

59. The system of any one of claims 1-58, wherein the first electrochemical cell is configured to produce Ca(OH)2 and Mg(OH)2 at the first cathode.

60. The system of any one of claims 1-58, wherein the first electrochemical cell is configured to produce Ca(OH)2 at the first cathode and Mg(OH)2 at the second cathode.

61. The system of any one of claims 1-58, wherein the first electrochemical cell is configured to produce Mg(OH)2 at the first cathode and Ca(OH)2 at the second cathode.

62. The system of any one of claims 1-58, wherein the first electrochemical cell is configured to produce Mg(0H)2 at the first cathode.Atty. Docket No.: UCH-40925UCLA Ref. No.: [UCLA 2024-285-1] WO63. The system of any one of claims 1-58, wherein the first electrochemical cell is configured to produce Ca(OH)2 at the first cathode.

64. The system of any one of claims 1-63, wherein the first hydroxide isolation chamber is configured to separate a hydroxide of a first target ion from a first hydroxide mixture comprising the hydroxide of the first target ion and a hydroxide of a non-target ion, thereby forming a second hydroxide mixture comprising the hydroxide of the non-target ion.

65. The system of claim 64, wherein the hydroxide of the first target ion is Mg(OH)2.

66. The system of claim 64, wherein the hydroxide of the first target ion is Ca(OH)2.

67. The system of any one of claims 64-66, wherein: the second hydroxide mixture further comprises a hydroxide of a second target ion; the second hydroxide isolation chamber is present and is configured to separate the hydroxide of the second target ion from the second hydroxide mixture, thereby forming a third hydroxide mixture comprising the hydroxide of the non-target ion.

68. The system of claim 67, wherein the hydroxide of the second target ion is Mg(OH)2.

69. The system of claim 67, wherein the hydroxide of the second target ion is Ca(OH)2.

70. The system of claim 64, wherein the first hydroxide mixture comprises sodium hydroxide, magnesium hydroxide, or a combination thereof.

71. The system of any one of claims 1-70, wherein the system is configured to produce calcium hydroxide.

72. The system of any one of claims 1-70, wherein the system is configured to produce magnesium hydroxide.

73. The system of any one of claims 1-72, wherein the system is configured to produce magnesium hydroxide and calcium hydroxide.Atty. Docket No.: UCH-40925UCLA Ref. No.: [UCLA 2024-285-1] WO74. A method of preparing a hydroxide of at least one target ion selected from Ca2+, Mg2+, and a combination thereof using the system of any one of claims 1-73, the method comprising the steps of: providing: an electrolyte solution comprising a non-target cation to the first anodic chamber; and a target ion stream to the first cathodic chamber; performing a first electrochemical process, comprising: applying a voltage to the first cathode and the first anode; thereby producing: a first acidic anolyte and an anodic gas at the first anode; and a first hydroxide mixture and a cathodic gas at the first cathode; wherein: the target ion stream comprises the at least one target ion; and the first hydroxide mixture comprises a hydroxide of the at least one target ion and a hydroxide of the non-target ion.

75. A method of preparing a hydroxide of at least one target ion, comprising: providing a first electrolyte solution comprising a non-target cation to a first anodic chamber of a first electrochemical cell, the first electrochemical cell further comprising: a first anode disposed within the first anodic chamber; a first cathodic chamber, comprising a first cathode; and a first membrane disposed between and configured to separate the first cathodic chamber and the first anodic chamber; wherein the first anodic chamber and the first cathodic chamber are in fluid communication; performing a first electrochemical process, comprising: applying a first voltage to the first cathode and the first anode; thereby producing: a first acidic anolyte and an anodic gas at the first anode; and a first hydroxide mixture and a cathodic gas at the first cathode; wherein the first acidic anolyte comprises an acid, and the first hydroxide mixture comprises a first hydroxide of at least one target ion and a hydroxide of the non-target ion; separating the first acidic anolyte into a first portion and a second portion;Atty. Docket No.: UCH-40925UCLA Ref. No.: [UCLA 2024-285-1] WO contacting the first portion of the first acidic anolyte with a source of the at least one target ion , thereby producing a CO2 stream and a target ion stream comprising the at least one target ion, wherein the CO2 stream comprises CO2; providing the target ion stream to the first cathodic chamber; and separating the first hydroxide of the at least one target ion from the first hydroxide mixture, thereby producing a second hydroxide mixture comprising the hydroxide of the nontarget ion.

76. The method of claim 75, wherein the at least one target ion is one target ion.

77. The method of claim 76, wherein the at least one target ion is a first target ion and a second target ion.

78. The method of claim 77, wherein the second hydroxide mixture further comprises a hydroxide of the second target ion, and the method further comprises: separating the hydroxide of the second target ion from the second hydroxide mixture, thereby producing a third hydroxide mixture.

79. The method of claim 78, further comprising contacting the target ion stream with the second hydroxide mixture and providing the third hydroxide mixture to the first cathodic chamber.

80. The method of claim 75, further comprising: providing a second electrolyte solution comprising a non-target cation to a second anodic chamber of a second electrochemical cell, the second electrochemical cell further comprising: a second anode disposed within the second anodic chamber; a second cathodic chamber, comprising a second cathode; and a second membrane disposed between and configured to separate the second cathodic chamber and the second anodic chamber; wherein the second anodic chamber and the second cathodic chamber are in fluid communication;Atty. Docket No.: UCH-40925UCLA Ref. No.: [UCLA 2024-285-1] WO providing the second hydroxide mixture, which further comprises a second target ion to the second cathodic chamber; performing a second electrochemical process, comprising: applying a second voltage to the second cathode and the second anode; thereby producing: a second acidic anolyte and the anodic gas at the second anode; and a third hydroxide mixture and the cathodic gas at the second cathode; wherein the second acidic anolyte comprises an acid, the second hydroxide mixture comprises a second target ion and the hydroxide of the non-target ion, and the third hydroxide mixture comprises a hydroxide of the second target ion and the hydroxide of the non-target ion; and separating the hydroxide of the second target ion from the third hydroxide mixture, thereby producing a fourth hydroxide mixture comprising the hydroxide of the non-target ion.

81. The method of claim 80, further comprising: separating the second acidic anolyte into a third portion and a fourth portion; contacting the third portion of the acidic anolyte with a source of the at least one target ion thereby producing the CO2 stream and the target ion stream comprising the at least one target ion.

82. The method of any one of claims 75-81, wherein contacting the first portion of the first acidic anolyte with a source of the at least one target ion further comprises contacting the first acidic anolyte and the source of the at least one target ion with a stripping gas.

83. The method of claim 82, wherein the CO2 stream comprises the stripping gas and CO2.

84. The method of any one of claims 75-83, further comprising removing CO2 from the CO2 stream.

85. The method of claim 84, wherein removing CO2 from the CO2 stream comprises contacting the CO2 stream with the second hydroxide mixture, or, when present, the fourthAtty. Docket No.: UCH-40925UCLA Ref. No.: [UCLA 2024-285-1] WO hydroxide mixture, thereby producing a carbonate of the non-target ion and, when present, the stripping gas.

86. The method of claim 84, wherein the carbonate of the non-target ion comprises Na2COs, NaHCCL, or a combination thereof.

87. The method of any one of claims 75-85, wherein the non-target ion is Na+.

88. The method of any one of claims 75-87, wherein the first electrolyte solution and, when present, the second electrolyte solution comprise NaCl.

89. The method of any one of claims 75-88, wherein the first acidic anolyte and, when present, the second acidic anolyte comprise HC1.

90. The method of any one of claims 75-89, wherein the acid comprises H+, H3CL, or a combination thereof.

91. The method of any one of claims 82-90, wherein the stripping gas comprises air.

92. The method of any one of claims 82-91, wherein the stripping gas comprises less CO2 than ambient air.

93. The method of any one of claims 82-92, wherein the stripping gas comprises less than about 1 atm CO2, or preferably less than about 0.01 atm CO2.

94. The method of any one of claims 82-93, wherein the stripping gas is essentially free of CO2.

95. The method of any one of claims 75-94, wherein the target ion stream further comprises a conjugate base of the acid.

96. The method of any one of claims 75-95, wherein the target ion stream comprises CaCl2.Atty. Docket No.: UCH-40925UCLA Ref. No.: [UCLA 2024-285-1] WO97. The method of any one of claims 75-96, wherein the first membrane is selective for the passage of the non-target ion from the first anodic chamber to the first cathodic chamber, and, when present, the second membrane is selective for the passage of the non-target ion from the second anodic chamber to the second cathodic chamber.

98. The method of any one of claims 75-97, wherein the first membrane is selective for the passage of Na+from the first anodic chamber to the first cathodic chamber, and, when present the second membrane is selective for the passage of Na+from the second anodic chamber to the second cathodic chamber.

99. The method of any one of claims 75-98, wherein the membrane comprises a cation exchange membrane (CEM, e.g., a sulfonated tetrafluoroethylene based fluoropolymercopolymer), anion exchange membrane (AEM), a non-selective barrier material, or a combination thereof.

100. The method of any one of claims 75-99, wherein the cathodic gas comprises EE.

101. The method of any one of claims 75-100, wherein the anodic gas comprises O2.

102. The method of any one of claims 75-101, further comprising dechlorinating the anodic gas.

103. The method of claim 102, wherein dechlorinating the anodic gas comprises contacting the anodic gas with a dechlorinating agent, thereby reducing Ch to CL ions and producing a dechlorinated gas comprising O2.

104. The method of claim 103, wherein the dechlorinating agent comprises magnesium, calcium, a sorbent comprising carbon (e.g., activated carbon), or an alkaline material (e.g., a solid comprising an alkaline material or a solution comprising an alkaline material).

105. The method of claim 103 or 104, wherein the dechlorinating agent is or is derived from the second hydroxide mixture, the fourth hydroxide mixture, when present, or a combination thereof.Atty. Docket No.: UCH-40925UCLA Ref. No.: [UCLA 2024-285-1] WO106. The method of any one of claims 75-105, wherein the first anode and, when present, the second anode are oxygen-selective anodes.

107. The method of any one of claims 75-106, wherein the first cathode and, when present, the second cathode comprise iron, iron alloy, nickel, nickel alloy, titanium, titanium alloy, aluminum, aluminum alloy, platinum, or a combination thereof.

108. The method of any one of claims 75-107, wherein the first cathode and, when present, the second cathode further comprise a coating comprising platinum, nickel phosphate, or molybdenum sulfate.

109. The method of any one of claims 75-108, wherein the first cathode and, when present, the second cathode are in the form of a mesh, plate, or rod.

110. The method of any one of claims 75-109, wherein the first cathode and, when present, the second cathode are in the form of a mesh.

111. The method of any one of claims 75-110, wherein the first cathode and, when present, the second cathode are in the form of a mesh comprising Pt and Ti.

112. The method of any one of claims 75-111, wherein the first cathode and, when present, the second cathode are in the form of a mesh comprising stainless steel (e.g., a 316 stainless steel mesh).

113. The method of any one of claims 75-112, wherein the first cathode and, when present, the second cathode are in the form of a plate.

114. The method of claim 113, wherein the first cathode and, when present, the second cathode are in the form of a plate comprising Ti having a coating comprising Pt.

115. The method of claim 113, wherein the first cathode and, when present, the second cathode are in the form of a plate comprising Ni.Atty. Docket No.: UCH-40925UCLA Ref. No.: [UCLA 2024-285-1] WO116. The method of any one of claims 75-115, wherein the first anode and, when present, the second anode comprise a group VIII metal, a group IX metal, a group X metal, titanium clad with a group VIII metal, titanium clad with a group IX metal, titanium clad with a group X metal, titanium clad with mixed metal oxide, or a combination thereof.

117. The method of any one of claims 75-116, wherein the first anode and, when present, the second anode further comprise iridium, tin, cobalt, manganese, tantalum, ruthenium, graphite, graphene, or carbon nanotube(s).

118. The method of any one of claims 75-117, wherein separating the hydroxide of the at least one target ion from the first hydroxide mixture comprises filtering the first hydroxide mixture.

119. The method of any one of claims 75-118, wherein separating the hydroxide of the at least one target ion from the first hydroxide mixture comprises clarifying the first hydroxide mixture.

120. The method of any one of claims 75-119, wherein separating the hydroxide of the at least one target ion from the first hydroxide mixture comprises clarifying the first hydroxide mixture.

121. The method of any one of claims 75-120, wherein separating the hydroxide of the at least one target ion from the first hydroxide mixture comprises sedimentation of the first hydroxide mixture.

122. The method of any one of claims 78-121, wherein separating the hydroxide of the second target ion from the third hydroxide mixture comprises filtering the third hydroxide mixture.

123. The method of any one of claims 78-122, wherein separating the hydroxide of the second target ion from the third hydroxide mixture comprises clarifying the third hydroxide mixture.Atty. Docket No.: UCH-40925UCLA Ref. No.: [UCLA 2024-285-1] WO124. The method of any one of claims 78-123, wherein separating the hydroxide of the second target ion from the third hydroxide mixture comprises clarifying the third hydroxide mixture.

125. The method of any one of claims 78-124, wherein separating the hydroxide of the second target ion from the third hydroxide mixture comprises sedimentation of the third hydroxide mixture.

126. The method of any one of claims 75-125, wherein a split ratio of the first portion of the acidic anolyte to the second portion of the acidic anolyte is from about 1 :9 to about 9: 1.

127. The method of claim 126, wherein the split ratio is about 2: 1.

128. The method of any one of claims 75-127, wherein the method has a gross Electrical Energy Intensity (gEEI) of less than about 5 MWh / MT(CaOH2).

129. The method of any one of claims 75-128, wherein the method has a gEEI of about 2 MW / MT(Ca(0H)2)..

130. The method of any one of claims 75-129, further comprising discharging the second portion of the acidic anolyte.

131. The method of any one of claims 75-130, further comprising neutralizing the second portion of the acidic anolyte.

132. The method of any one of claims one of claims 75-131, performed using the system of any one of claims 1-73.

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