# US 11,998,875 B2 · System and method for electrochemical ocean alkalinity enhancement > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,998,875 B2 - Document ID: US11998875B2 - Status: Granted - Kind: B2 - Application number: 18/266,672 - Filed: 2022-12-22 - Published: 2023-12-07 - Granted: 2024-06-04 - Earliest claimed: 2021-12-22 - Assignees: The Research Foundation for The State University of New York York - Applicants: The Research Foundation for the State University of New York - Inventors: Matthew Eisaman - Web page: https://patentgrep.com/patent/US11998875B2 ## CPC - B01D 61/445: {with bipolar membranes; Water splitting} - B01D 61/46: Apparatus therefor - C02F 1/4618: {for producing "ionised" acidic or basic water} - C02F 1/4693: {electrodialysis} - C02F 1/66: by neutralisation; pH adjustment (for degassing C02F1/20; using ion-exchange C02F1/42; for flocculation or precipitation of suspended impurities C02F1/52; for removing dissolved compounds C02F1/58) - B01D 2311/18: pH control - B01D 2313/14: Specific spacers - B01D 2313/143: on the feed side - B01D 2313/146: on the permeate side - B01D 2317/02: Elements in series - C02F 1/441: {by reverse osmosis} - C02F 2001/4619: {only cathodic or alkaline water, e.g. for reducing} - C02F 2103/06: Contaminated groundwater or leachate - C02F 2103/08: Seawater, e.g. for desalination - C02F 2103/10: from quarries or from mining activities - C02F 2201/46115: Electrolytic cell with membranes or diaphragms - C02F 2201/46135: Voltage - C02F 2201/4614: Current - C02F 2201/46145: Fluid flow - C02F 2301/08: Multistage treatments, e.g. repetition of the same process step under different conditions - C02F 2303/22: Eliminating or preventing deposits, scale removal, scale prevention (C02F1/042, C02F1/4602, C02F5/00 take precedence) - Y02A 20/131: Reverse-osmosis - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) - C02F: TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE (separation in general B01D; special arrangements on waterborne vessels of installations for treating water, waste water or sewage, e.g. for producing fresh water, B63J; adding materials to water to prevent corrosion C23F; treating radioactively-contaminated liquids G21F9/04; regeneration of reactants for recirculation into processes, see the relevant places for the processes) - Y02A: TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE ## Abstract The disclosure relates to enhancing alkalinity of brine, e.g. seawater, using bipolar membrane electrodialysis (BPMED) without removing divalent cations that otherwise cause scaling. In one embodiment, a BPMED is employed wherein the brine volumetric flow rate through a basification compartment is greater at a given current density than that through a brine compartment which increases the pH of the brine output while keeping it below the precipitation pH. In one embodiment, the spacer located in the basification compartment is thicker than spacers elsewhere in the BPMED so as resist membrane distortion due to the increased hydrostatic pressure in the basification compartment given the greater volumetric flow. The brine output having increased alkalinity can be returned to the ocean to mitigate acidification and enable capture of atmospheric carbon dioxide. ## Claims ### Claim 1 A method for enhancing alkalinity comprising: (i) providing a bipolar membrane electrodialysis device (BPMED) which comprises electrodes and at least one unit comprised of a brine compartment, an acid compartment, and a base compartment; (ii) flowing an aqueous brine solution through the base compartment at a first volumetric flow rate (fba) and through the brine compartment at a second volumetric flow rate (fbr), the aqueous brine solution comprising at least one divalent cation that precipitates out of the aqueous brine solution to form a solid precipitate when the aqueous brine solution is at or above a precipitating pH; (iii) applying a voltage between the electrodes at a current density to the BPMED device to form, in the base compartment, an enhanced pH alkaline brine product that has a pH higher than the pH of the brine but below the precipitating pH; (iv) maintaining, at the current density, the first volumetric flow rate through the base compartment at a rate sufficiently greater than the second volumetric flow rate through the brine compartment so as to keep the pH of the enhanced pH alkaline brine product formed in the base compartment below the precipitating pH; and (v) outputting the enhanced pH alkaline brine product from the base compartment. ### Claim 2 (depends on 1) The method of claim 1 wherein the aqueous brine solution flowing to the base compartment and flowing to the brine compartment is from a brine source, which brine source is the same or a different source for each of the base compartment and the brine compartment individually. ### Claim 3 (depends on 2) The method of claim 2 wherein the aqueous brine solution is flowed directly from the brine source to the base compartment, flowed directly to the brine compartment, or flowed directly to both. ### Claim 4 (depends on 1) The method of claim 1 wherein the aqueous brine solution comprises seawater, reverse osmosis concentrate brine, or both. ### Claim 5 (depends on 2) The method of claim 2 wherein the brine source is a natural body of seawater or a mined salt dissolved to make an aqueous brine solution. ### Claim 6 (depends on 1) The method of claim 1 wherein the divalent cation is selected from the divalent cation of calcium (Ca), magnesium (Mg), or both; and the precipitate is selected from CaCO3, or Mg(OH)2, or both. ### Claim 7 (depends on 1) The method of claim 1 wherein the pH of the brine is about 6 to about 8.5; the precipitating pH is about 8.9 or above; and the pH of the enhanced pH alkaline brine product is about 8.5 to about 8.9. ### Claim 8 (depends on 1) The method of claim 1 wherein the first volumetric flow rate is greater than 1 to about 10 times greater than the second volumetric flow rate. ### Claim 9 (depends on 1) The method of claim 1 wherein least a portion of the enhanced pH alkaline brine product outputted from the base compartment is flowed into a body of seawater. ### Claim 10 (depends on 1) The method of claim 1 wherein a partially desalinated brine product is formed in and outputted from the brine compartment, and at least a portion of the desalinated brine product outputted from the brine compartment is combined with at least a portion of the enhanced pH alkaline brine product outputted from the base compartment. ### Claim 11 (depends on 1) The method of claim 1 wherein a partially desalinated brine product is formed in and outputted from the brine compartment, and at least a portion of the desalinated brine product outputted from the brine compartment is inputted to the base compartment. ### Claim 12 (depends on 10) The method of claim 10 wherein the combination of the partially desalinated brine product and the enhanced pH alkaline brine product are flowed into a body of seawater. ### Claim 13 (depends on 10) The method of claim 10 wherein the desalinated brine product outputted from the brine compartment has a pH of about 8.5 or lower; and the pH of the combined desalinated brine product and the enhanced alkaline brine product is about 8.1 to about 8.9. ### Claim 14 (depends on 1) The method of claim 1 wherein the brine compartment, the acid compartment, and the base compartment are included in a cell triplet and the BPMED comprises a plurality of cell triplets in series, and wherein the voltage applied across the electrodes is about 1V to about 4V per cell triplet, and the current density is about 5 mA/cm2 to about 120 mA/cm2. ### Claim 15 (depends on 1) The method of claim 1 wherein an aqueous stream comprising a first concentration of HCl is flowed into the acid compartment, and an acidified product having a second concentration of HCl greater than the first concentration is formed in and outputted from the acid compartment. ### Claim 16 (depends on 15) The method of claim 15 wherein the aqueous stream comprises a combination of at least a portion of the acidified product outputted from the acid compartment and a water feed. ### Claim 17 (depends on 16) The method of claim 16 wherein the water feed comprises deionized water or brine. ### Claim 18 (depends on 16) The method of claim 16 wherein a first portion of the aqueous stream is recovered as an HCl product having an HCl concentration of about 0.1M to about 1M and a second portion of the aqueous stream is flowed into the acid compartment.