La Plante Erika Callagon, Chen Xin, Bustillos Steven, Bouissonnie Arnaud, Traynor Thomas, Jassby David, Corsini Lorenzo, Simonetti Dante A, Sant Gaurav N
Department of Materials Science and Engineering, University of Texas at Arlington, Arlington, Texas 76019, United States.
Institute for Carbon Management, University of California, Los Angeles, Los Angeles, California 90024, United States.
ACS ES T Eng. 2023 Apr 27;3(7):955-968. doi: 10.1021/acsestengg.3c00004. eCollection 2023 Jul 14.
We present the mass balances associated with carbon dioxide (CO) removal (CDR) using seawater as both the source of reactants and as the reaction medium via electrolysis following the "" (") process. This process, extensively detailed in La Plante E.C.; ACS Sustain. Chem. Eng.2021, 9, ( (3), ), 1073-1089, involves the application of an electric overpotential that splits water to form H and OH ions, producing acidity and alkalinity, i.e., in addition to gaseous coproducts, at the anode and cathode, respectively. The alkalinity that results, i.e., via the "continuous electrolytic pH pump" results in the instantaneous precipitation of calcium carbonate (CaCO), hydrated magnesium carbonates (e.g., nesquehonite: MgCO·3HO, hydromagnesite: Mg(CO)(OH)·4HO, etc.), and/or magnesium hydroxide (Mg(OH)) depending on the CO ion-activity in solution. This results in the trapping and, hence, durable and permanent (at least ∼10 000-100 000 years) immobilization of CO that was originally dissolved in water, and that is additionally drawn down from the atmosphere within: (a) mineral carbonates, and/or (b) as solvated bicarbonate (HCO) and carbonate (CO) ions (i.e., due to the absorption of atmospheric CO into seawater having enhanced alkalinity). Taken together, these actions result in the net removal of ∼4.6 kg of CO per m of seawater catholyte processed. Geochemical simulations quantify the extents of net CO removal including the dependencies on the process configuration. It is furthermore indicated that the efficiency of realkalinization of the acidic anolyte using alkaline solids depends on their acid neutralization capacity and dissolution reactivity. We also assess changes in seawater chemistry resulting from Mg(OH) dissolution with emphasis on the change in seawater alkalinity and saturation state. Overall, this analysis provides direct quantifications of the ability of the process to serve as a means for technological CDR to mitigate the worst effects of accelerating climate change.
我们展示了与使用海水作为反应物来源和反应介质，通过电解遵循“ ”（“ ”）过程去除二氧化碳（CO₂）相关的质量平衡。该过程在La Plante E.C.；ACS Sustain. Chem. Eng.2021, 9, ( (3), ), 1073 - 1089中有详细阐述，涉及施加一个过电势来分解水形成H⁺和OH⁻离子，分别在阳极和阴极产生酸性和碱性，即除了气态副产物之外。由此产生的碱度，即通过“连续电解pH泵”，会导致碳酸钙（CaCO₃）、水合碳酸镁（例如，菱镁矿：MgCO₃·3H₂O，水菱镁矿：Mg₅(CO₃)₄(OH)₂·4H₂O等）和/或氢氧化镁（Mg(OH)₂）的瞬时沉淀，这取决于溶液中CO₃²⁻离子的活度。这导致了原本溶解在水中的CO₂的捕获，进而实现持久且永久（至少约10000 - 100000年）的固定，并且额外地从大气中吸收进来：（a）以矿物碳酸盐的形式，和/或（b）以溶剂化的碳酸氢根（HCO₃⁻）和碳酸根（CO₃²⁻）离子的形式（即由于大气中的CO₂被吸收到碱度增强的海水中）。综合起来，这些作用导致每处理1立方米海水阴极电解液净去除约4.6千克的CO₂。地球化学模拟量化了净CO₂去除的程度，包括对过程配置的依赖性。此外还表明，使用碱性固体对酸性阳极电解液进行再碱化的效率取决于它们的酸中和能力和溶解反应性。我们还评估了由于Mg(OH)₂溶解导致的海水化学变化，重点关注海水碱度和饱和状态的变化。总体而言，该分析直接量化了 过程作为一种技术手段用于去除CO₂以减轻加速气候变化最坏影响的能力。
