ORIGINAL RESEARCH article
Front. Clim.
Sec. Carbon Dioxide Removal
Volume 7 - 2025 | doi: 10.3389/fclim.2025.1616362
This article is part of the Research TopicEnvironmental Engineering Perspectives on Ocean-Based Carbon Dioxide RemovalView all 7 articles
Using Magnesium Hydroxide for Ocean Alkalinity Enhancement: Elucidating the Role of Formation Conditions on Material Properties and Dissolution Kinetics
Provisionally accepted
- 1Department of Chemistry, Stony Brook University, Stony Brook, United States
- 2Department of Electrical and Computer Engineering, Stony Brook University, Stony Brook, New York, United States
- 3Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration (NOAA), Seattle, Washington, United States
- 4Cooperative Institute for Climate, Ocean and Ecosystem Studies, College of the Environment, University of Washington, Seattle, Washington, United States
- 5Unaffiliated Researcher, Seattle, United States
- 6Google, Seattle, United States
- 7Department of Earth & Planetary Sciences, Yale University, New Haven, Connecticut, United States
- 8Yale Center for Natural Carbon Capture, Yale University, New Haven, Connecticut, United States
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Mg(OH)2 holds potential as an alkalinity source for Ocean Alkalinity Enhancement (OAE). Alkalinity exchange occurs between electrochemically derived NaOH and Mg-rich reverse osmosis reject brine, a byproduct of desalination treatment, producing "seawater-precipitated" Mg(OH)2. Characterization found no chemical composition difference among seawater-precipitated and industrial sourced Mg(OH)2 with both having high (>98%) purity. Differences were found with the crystallinity with industrial sources containing a higher degree of crystallinity of 0.83-0.85 compared to 0.16-0.33 for seawater-precipitated paste. Mg(OH)2 with a higher degree of crystallinity (>80%) This is a provisional file, not the final typeset article had significantly slower dissolution rates than Mg(OH)2 with a lower degree of crystallinity (<20%). Results revealed that there is a strong inverse relation between degree of crystallinity and dissolution rate of both seawater-precipitated and industrial sourced Mg(OH)2. Seawater-precipitated Mg(OH)2, with its similar purity to industrial sources yet faster and more complete dissolution and alkalinity release, could hold an advantage over other alkalinity sources for OAE applications with its seemingly tunable dissolution kinetics.
Keywords: Magnesium Hydroxide, ocean alkalinity enhancement, Marine Carbon DioxideRemoval, Seawater Precipitation, crystallinity, Materials Science
Received: 22 Apr 2025; Accepted: 25 Sep 2025.
Copyright: © 2025 Shaw, Ringham, Carter, Tyka and Eisaman. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Cody Shaw, cody.shaw@stonybrook.edu
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