Membrane-free electrochemical production of acid and base solutions capable of processing ultramafic rocks
Bibliographic record
Abstract
Electrochemical production of acid and base from water enables their use as regenerable reagents in closed-loop processes, with attractive applications including CO2 capture or mineralization and low-temperature production of Ca(OH)2. Conventional systems utilize ion exchange membranes (IEMs) to inhibit H+/OH– recombination, which leads to high resistive losses that compromise energy efficiency and poor tolerance for polyvalent metal ions that complicates applications involving mineral resources. Here we use ion transport modeling to guide the design of a system that uses a simple porous separator instead of IEMs. Using H2 redox reactions for H+/OH– production, we demonstrate acid-base production at useful concentrations in the presence of polyvalent impurities with lower energy demand and higher current density than reported IEM-based systems. Cells can be stacked by combining H2 electrodes into a bipolar gas diffusion electrode, which recirculates H2 with near-unity efficiency. We show that the cell outputs extract alkalinity from olivine and serpentine as Mg(OH)2 and Mg3Si2O6(OH)2, which remove CO2 from ambient air to form Mg carbonates. These studies establish the principles for membrane-free electrochemical acid-base production, enabling closed-loop resource recovery and material processing powered by renewable electricity. Electrochemical acid-base production has attractive applications in mineral recovery and CO2 removal, but current membrane-based designs are plagued by resistive losses. The authors report a membrane-less system generating useful acid and base solutions at high rates with less energy.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".