Mining waste-driven carbon capture via ocean alkalinity enhancement

Gregorich, Nicholas [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000156889492); Kalla, Joseph [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)] (ORCID:0009000717112681); Irwin, Mary Hannah [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)] (ORCID:0000000304435610); Pethe, Saurabh Prakash [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000227591774); Abbas, Mustafa [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)] (ORCID:0009000594810163); Coin, Zachary [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)]; Paranthaman, Mariappan Parans [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000330098531); Uddin, Majbah [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000199253881); Dangwal, Shailesh [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000218667757); Bhave, Ramesh [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000334309914); Islam, Syed Z. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000251498094)

doi:10.1016/j.ccst.2026.100629

DOE OSTI · 3368799

Mining waste-driven carbon capture via ocean alkalinity enhancement

View original source ↗Read source document ↗Export metadata ↓

Abstract

Ocean alkalinity enhancement (OAE) has emerged as a promising strategy to mitigate ocean acidification and reduce global warming. Traditional metal (e.g., critical materials) mining industries release alkaline waste via mining tailings with high concentrations (99.2%) of calcium and magnesium oxide (CaO, MgO). Incorporating mining waste into OAE processes is less energy intensive than processes relying on calcination of limestone for CaO production. The solubility limit of simulated mining waste in American Society for Testing and Materials (ASTM) seawater is 75 mg⋅L -1 , which can sequester 118 mg of carbon dioxide (CO 2 ). The solubility in seawater retrieved from Sunset Beach, FL was 25 mg⋅L -1 . Changes in pH, total alkalinity, and total inorganic carbon were analyzed to confirm the successful addition of simulated alkaline mining waste without the formation of secondary precipitation. This study proposes a new OAE strategy where a facility is developed nearby ocean waters that mixes alkaline waste with seawater. Subsequently, the seawater is met with previously captured, pure CO 2 to bring the pH back to 8.2 and eliminate the risks of pH shock and secondary precipitation. Technoeconomic analysis estimated an energy requirement of 1.4 GJ per ton of CO 2 stored that resulted in a processing cost of $\$$266 per ton of CO 2 sequestered (4.2 GJ per ton, $\$$807 per ton of CO 2 for real seawater). Results from this study underscore the potential for utilizing mining waste in OAE processes and provide a pathway for practical deployment.

Explore related subjects

Absorption Carbon capture Mining Mining waste

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Gregorich, Nicholas [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000156889492), Kalla, Joseph [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)] (ORCID:0009000717112681), Irwin, Mary Hannah [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)] (ORCID:0000000304435610), Pethe, Saurabh Prakash [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000227591774), Abbas, Mustafa [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)] (ORCID:0009000594810163), Coin, Zachary [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)], Paranthaman, Mariappan Parans [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000330098531), Uddin, Majbah [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000199253881), Dangwal, Shailesh [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000218667757), Bhave, Ramesh [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000334309914), Islam, Syed Z. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000251498094). 2026-05-15. Mining waste-driven carbon capture via ocean alkalinity enhancement. https://doi.org/10.1016/j.ccst.2026.100629

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related reports

DOE OSTI2026

Deactivating Emission in Azulene via Solvent-Induced (Anti)Aromaticity

Anti-Kasha emission is a coveted feature in optoelectronics, with promise in areas such as imaging, sensing, and the production of white-light LEDs via dual-photon emission. Despite being a rare feature in organic systems, anti-Kasha emission is readily observed in the deceptively simple molecule azulene, which possesses two bright singlet states in the UV–visible spectrum and readily emits from the S 2 state. With dominant anti-Kasha emission and decades of synthetic study, azulene is a perfect candidate for novel material fabrication; however, large gaps persist in understanding the photophysics of even the simple parent compound. These range from competing, experimentally unverified models of azulene reactivity and aromaticity to the unexplained deactivation of anti-Kasha emission in a host of azulene derivatives. Herein, we use fluorescence and transient absorption spectroscopies to explore the detailed solvent dependence of azulene photophysics. We discover a tunable reduction in the S 2 lifetime via weak complexation with aromatic solvents. Interestingly, our results are independent of polarity, highlighting the primacy of peripherally delocalized 10-π Hückel aromaticity over zwitterionic character. When the dipolar character is enhanced through chemical functionalization, we observe even greater sensitivity to solvent aromaticity and more rapid quenching, revealing the role of conical intersections in azulenes with zwitterionic excited states. Overall, this work provides essential mechanistic insight into the photophysics of azulene and reveals a simple new approach to control the excited-state aromaticity and anti-Kasha emission in this class of materials.

Absorption↗

DOE OSTI2026

Role of the Character of the Excited State of Singly Reduced Rh 2 (II,II) Intermediates on Photocatalytic Activity

Singly reduced intermediates have recently been implicated as photoactive intermediates in a number of important reactions; however, their photophysical properties remain poorly understood. A series of dirhodium(II,II) complexes, cis-[Rh 2 (p-R-Form) 2 (bncn) 2 ] 2+ (bncn = benzo[c]cinnoline; p-R-Form = N,N′-di-p-R-phenylformamidinate), where R = −OCH 3 (1), −CH 3 (2), −H (3), −F (4), −Cl (5), and −CF 3 (6), and their respective radical anions were prepared and their excited state properties were investigated. Complex 3 acted as a singlemolecule photocatalyst for H 2 production with red light. Substitution on the formamidinate ligands in 1−6 affected the energy of the Rh 2 (δ*)/Form(π,nb) highest occupied molecular orbital (HOMO), consistent with the metal/ligand-to-ligand charge transfer ( 1 ML-LCT) absorption maxima and the 3 ML-LCT excited state lifetime, ranging from 1.6 ns in 1 to 54 ns in 6 in CH 3 CN. The highest turnover number for photocatalytic H 2 evolution was observed for 3, and the lowest values were for 1 and 6. The radical anion, [Rh 2 ] − , formed during photocatalysis, was shown to absorb a photon and undergo a second reduction. The lifetimes of the doublet excited states of [3] − and [6] − were 0.49 and 0.24 ns, respectively. Calculations showed that the lowest energy excited state in [3] − was 2 ML-LCT, whereas that in [6] − was a bncn − → Rh 2 (σ*) ligand-to-metal charge transfer ( 2 LMCT) state. The 2 LMCT state stabilized across the series from [1] − to [6] − , pointing at its role in modulating the photophysical properties. This work highlights the importance of the reductive quenching of [Rh 2 ] − and the generation of the doubly reduced species to effectively catalyze hydrogen evolution.

Absorption↗

DOE OSTI2026

Surface-Initiated Atom Transfer Radical Polymerization Using Hydrogel Reactors

Atom transfer radical polymerization (ATRP) is a controlled radical polymerization method that enables the synthesis of tailored polymeric materials with low dispersity, highlighting its immense potential for green fabrication of advanced materials. However, its broader implementation is limited by challenges in product isolation, maintaining catalyst activity, and mitigating atmospheric sensitivity arising from oxygen-sensitive metal catalysts. Here, gelatin hydrogels (GHs) are introduced as a soft “reactor” matrix for interfacial ATRP, operating with minimal metal-catalyst loading while exhibiting possibly an organoreductive behavior. This strategy leverages activator regeneration via electron transfer through a ligand–metal charge-transfer (LMCT) mechanism to reduce oxidized metal catalysts within the GH network. Polymerization is evaluated by growing polymer brushes at an active interface formed between GHs swollen in monomer solution and an initiating surface, and sequential growth experiments confirmed that GH-mediated ATRP preserves living character. Under UV illumination, LMCT is activated, producing polymers both at the desired interface and within the GH bulk. UV–Vis spectroscopy revealed active reduction of Cu(II) to Cu(I) along with concentration-dependent complex formation, indicating dynamic coordination chemistry within the hydrogel. The redox-active arginine- and glutamic acid-rich gelatin backbone coordinates and reduces the metal center, enabling ATRP at ppm-level catalyst concentrations. While polymerization proceeds in GH-Cu(II) reactors, adding external mobile ligands to the GH results in longer polymer brushes. Here, the results reported here are exploratory. More experiments are needed to characterize polymer brush growth in GHs and compare it to conventional surface-initiated polymerization in solution.

Absorption↗