Experimental Observations of Carbon Mineralization in Dead end and Flowing Fractures [Slides]
Goal: Gain a fundamental understanding of how fracture characteristics impact mineralization in a stagnant (dead-end) fracture.
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Goal: Gain a fundamental understanding of how fracture characteristics impact mineralization in a stagnant (dead-end) fracture.
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For presentation at ACS Fall 2023, San Francisco, CA, August 13-17, 2023.
Abstract This study examines the potential of Midcontinent Rift rocks to facilitate long‐term CO 2 sequestration by providing the necessary Ca and Mg for carbonate mineralization. Surface samples were collected from the Oronto and Bayfield‐Jacobsville Groups around Lake Superior and used for petrography and X‐ray diffraction to determine their mineral composition. Also, X‐ray fluorescence was also used to assess their bulk chemical composition. The samples were then exposed to CO 2 and deionized water in Teflon‐lined vessels at 90°C, and the resulting leachate fluids were analyzed for the cation released during the testing. SEM microscopy was used to examine the samples for potential mineralization of carbonate minerals. The Oronto Group sediments consist primarily of feldspathic to feldspathic lithic arenites with a chlorite‐dominated matrix, and the primary porosity is blocked by calcite and hematite cement. The Bayfield–Jacobsville sequences are porous quartz arenites to feldspathic quartz arenites that do not contain significant accumulation of Ca‐, Mg‐, and Fe‐bearing minerals. The leachate fluids obtained from Oronto Group samples exhibit a maximum Ca release rate (5.2 × 10 −4 mole/cm 2 .day), indicating rapid calcite cement dissolution and increased porosity and permeability. SEM/EDS microanalysis revealed areas where pore‐filling calcite was preferentially dissolved. Longer‐term rock‐water reactions resulted in induced carbonate mineralization, as evidenced by calcite crystals observed in a sample reacted for 102 days. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd.
Sequestration of CO 2 within stable mineral carbonates (e.g., CaCO 3 ) represents an attractive emission reduction strategy because it offers a leakage-free alternative to geological storage of CO 2 in an environmentally benign form. However, the pH of aqueous streams equilibrated with gaseous streams containing CO 2 (pH < 4) are typically lower than that which is required for carbonate precipitation (pH > 8). Traditionally, alkalinity is provided by a stoichiometric reagent (e.g., NaOH) which renders these processes environmentally hazardous and economically unfeasible. This work investigates the use of regenerable ion-exchange materials to induce alkalinity in CO 2 -saturated aqueous solutions such that the pH shift required for mineralization occurs without the need for stoichiometric reagents. Na + -H + exchange isotherms (at [H + ] = 10 −8 –10 −1 M) and rates were measured for 13X and 4A zeolites and TP-207 and TP-260 organic exchange resins in batch equilibrium and fixed-bed exchange experiments, respectively. At solutions equilibrated with CO 2 at 1.0 atm (pH = 3.9), H + exchange capacities for the materials were similar (1.7–2.4 mmol H + /g material) and resulted in pH increases from 3.9 to greater than 8.0. Multi-component mixtures using Ca 2+ and Mg 2+ cations (at 10 −3 –10 −1 M) in CO 2 -saturated water were used to probe competitive ion exchange. The presence of divalent cations in solution inhibited H + exchange, reducing capacities to as low as 0.2 mmol H + /g for both resins and zeolites. Dynamic H + exchange capacities in fixed-bed ion exchange columns were similar to equilibrium values for resins (∼1.5 mmol/g) and zeolites (∼0.8 mmol/g) using inlet solutions that were equilibrated with gaseous streams of CO 2 at 1.0 atm. However, exchange kinetics were limited by intraparticle diffusion as indicated by the increased rate parameters with increasing inlet flow rates (20–160 cm 3 min −1 ). Experimental calcite precipitation from mixing the alkaline CO 3 2− -rich water solution obtained from the ion-exchange column with a simulated liquid waste stream solution achieved thermodynamic maximum yields. The results from these studies indicate that ion exchange processes can be used as an alternative to the addition of stoichiometric bases to induce alkalinity for the precipitation of CaCO 3 , thereby opening a pathway toward sustainable and economic mineralization processes.
Mafic and ultramafic rocks present an intriguing pathway for CO 2 capture through strategic enhancements to the natural silicate weathering cycle. Simultaneously, these rock types are often hosts to appreciable amounts of metals critical to U.S. energy independence, particularly in the context of alkaline mine tailings from historical metal mining. The research and scientific prerogative, then, is to identify promising mafic and ultramafic feedstocks and conduct exploratory studies to effectively recover these critical minerals while preserving the potential for mineral carbonation. The Keweenaw Peninsula of Michigan hosts the largest native Cu reservoir within basalt in the world and experienced a rich history of Cu production spanning from pre-historic times to the mid-1900s. Today, much of the Cu mining legacy remains as mine waste tailings. In this study, we examined the Cu extractability from Keweenaw Basalt tailings using a sodium glycinate solution, in comparison with acid and sodium hydroxide leaching. Experimental results showed an 85 % Cu extraction rate using sodium glycinate as the extraction solution with negligible release of other cations from the basalt. The kinetic and extraction mechanisms of Cu selective recovery using glycinate solution were discussed using time-resolved experimental data and kinetic geochemical modeling. Theoretical estimation of carbon mineralization potential of all the existing basalt waste tailings (∼500 million tons) can reach 85.5 MMT CO 2 . A total of 0.786 MMT Cu can be recovered with sodium glycinate, with a value of 7.7 billion USD. In conclusion, this novel application of alkaline glycinate for selective Cu recovery from basalt mine tailings demonstrates the viability of selective metal recovery using a non-hazardous chemical while preserving CO 2 capture potential and presents a potential pathway toward reducing energy-related emissions and providing an unconventional domestic source of critical minerals.
Early isotopic studies of sulfate in carbonate minerals (carbonate associated sulfate; CAS) suggested that carbonates can provide a reliable, well-dated archive of the marine sulfur cycle through time. However, subsequent research has shown that diagenetic alteration can impose highly heterogeneous CAS sulfur isotopic compositions (δ 34 S CAS ) among different carbonate phases within sediments. Such alteration necessitates targeted sampling of well-preserved, primary carbonate phases. Here, we present a new record of Carboniferous and Early Permian brachiopod δ 34 S CAS generated from over 130 measurements of microsampled brachiopod shells. Our record refines existing brachiopod δ 34 S CAS records and confirms a large, ~6.5‰ δ 34 S CAS decrease in the Early Carboniferous. Importantly, the record also features a novel 3–5‰ increase in δ 34 S CAS near the Serpukhovian-Bashkirian boundary (323.4 Ma) that coincides with carbonate δ 13 C and δ 18 O increases. Variability in δ 34 S CAS is minor both within (≤0.3‰) and among (≤2‰) individual co-depositional brachiopod specimens. A taxon-specific δ 34 S CAS offset is present one species (Composita subtilita) that also exhibits a δ 13 C offset, supporting the existence of biological “vital effects” on δ 34 S CAS . Geologic evidence and mathematical modeling of the Permo-Carboniferous carbon and sulfur cycles suggest that changes in the burial ratio of organic carbon to pyrite sulfur (R C:S ) are insufficient to explain the observed mid-Carboniferous δ 34 S CAS record. We find that changes in the 34 S depletion of pyrite relative to seawater sulfate ( 34 ε) or in the δ 34 S of the input to the ocean (δ 34 S in ) are also needed. Large additions of O 2 from organic carbon burial during the Permo-Carboniferous cannot be entirely compensated for with sulfur cycle changes; lower than modern late Visean pO 2 and/or additional O 2 sinks are needed to keep pO 2 at plausible levels. Based on the geologic context surrounding our record's mid-Carboniferous δ 34 S CAS increase, we advocate for simultaneous changes in pyrite burial, 34 ε, and δ 34 S in , driven by sea level or tectonically induced changes in environments of sulfur burial, as a viable mechanism to produce rapid seawater δ 34 S changes.
Not provided.
This dataset comprises soil-pyrogenic organic matter (PyOM) incubation experiments conducted in a laboratory setting. The focus was on measuring carbon dioxide (CO2) flux emitted in the headspace of incubation jars over a one-month period. The aim was to estimate carbon mineralization from two different carbon fractions in PyOM, as well as carbon mineralization from soil organic carbon (SOC). Bacterial and fungal community profiles were tracked at various time points during the incubation to observe changes in the overall community and specific responders to PyOM. LC-MS analysis of soil samples was also performed to monitor changes in the soil's chemical composition.The provided dataset includes processed CO2 flux measurements obtained from the Picarro-multiplexer measurement setup for each sample incubation jar. This data is available in the "CO2Flux.csv" file. Additionally, the dataset includes CO2 flux data partitioned to estimate mean carbon mineralization from the two PyOM carbon fractions, bulk PyOM, and SOC. The cumulative carbon mineralization data is provided in "cml_respired.csv," while the rate of carbon mineralization data is in "rate_respired.csv." The file "cml_respired_lastcyc.csv" contains cumulative carbon mineralization data for the PyOM carbon fractions, bulk PyOM, and SOC throughout the entire incubation period.For the LC-MS analysis, the raw data can be found in the "20220721_NZ_PeakHeights_FinalAnalysis.csv" file, while sample metadata is provided in "20220721_NZpilot_Metadata.csv". Processed LC-MS data is available in the file "20220721_NZ_FINAL_msdat_sub3.csv". Lastly, the dataset includes the relative abundance data for bacterial genera that exhibited a significant positive response to the addition of PyOM produced at 350 degrees Celsius, which can be found in "resp_genera_350.csv".
ABSTRACT The mineralization of carbon dioxide (CO 2 ) to stable carbonate products is a desirable process for carbon capture utilization and storage (CCUS). However, improving the process economics through creative use of available reactants is necessary to develop a scalable mineralization process. This study details the development of a semi‐continuous CO 2 mineralization process that uses flue gas as a point CO 2 source, produced water (PW) as an alkaline source of Ca 2+ , and NaOH effluent (potentially sourced from integration with the chlor‐alkali process. Operating at a controlled pH allowed for both complete reaction of available Ca 2+ (100% carbonation potential or 9.9 g CO 2 .L –1 PW brine) and for reproducible control of the produced calcium carbonate (CaCO 3 ) product. A full factorial design of experiments was implemented to study the effects of reaction temperature, pH, and gaseous CO 2 concentration on the mineralization and CO 2 capture rates as well as product crystalline structure and morphology. A maximum CO 2 capture rate of 0.315 ± 0.007 kg.L –1 .d –1 was achieved at 25°C and 25% CO 2 . CO 2 gas to liquid phase mass transport is believed to be the rate limiting step. With improved reactor design and optimization, the proposed semi‐continuous mineralization process shows promise for scaling to a pilot scale CO 2 capture technology.
CO2 sequestration in deep geologic formations can permanently reduce atmospheric CO2 emissions and help to abate climate change. Target formations must undergo a time- and resource-intensive site evaluation process, assessing storage capacity, environmental safety, and suitability for CO2 trapping via reactive transport models based on data from a limited number of core samples. As such, simulations are often simplified and omit heterogeneities in formation properties that may be significant but are not well understood. To facilitate more rapid site assessment, this work first defines the aquifer properties of favorable storage formations through the analysis of promising and active storage sites. Data show quartz is the most prevalent formation mineral with carbonate minerals, highly reactive with injected CO2, present in over 75% of formations. Porosity and permeability data are highly clustered at 10–30% and 10–1000 mD. Field-scale reactive transport simulations are then constructed and used to analyze CO2 trapping efficiency. The models consider porosity and carbonate mineral heterogeneity as well as the impacts of typical temperature gradients. Simulated sequestration efficiencies are compared to results from a comparable homogenous model to understand the implications of aquifer non-uniformities. The results show a lower sequestration efficiency in the homogeneous model during the injection phase. During the post-injection phase, the homogenization of porosity and carbonate mineralogy results in a higher sequestration efficiency. Incorporating the temperature gradient also increases the sequestration efficiency. Importantly, the maximum deviation between the homogeneous and heterogeneous simulations at the end of the 50-year study period is only ~10%. Larger impacts may be incurred for properties outside the defined, promising ranges suggested here.
Mineral-associated organic carbon (MAOC) is the largest terrestrial pool of organic carbon, yet controls on its formation remain unresolved. Existing MAOC is thought to preclude additional C storage on minerals, but this perspective is difficult to reconcile with observations that MAOC stacks in multilayers, suggesting that existing MAOC could promote greater C retention. Here, in a manipulative experiment using 118 soils from 15 agricultural sites across the United States, we show that MAOC formation is promoted by both existing MAOC and its counterpart—MAOC saturation deficit. The positive effect of existing MAOC on the formation of new MAOC persists after accounting for soil physicochemical properties that covary with MAOC. In contrast with current theory, we found that MAOC formation was not clearly influenced by microbial carbon-use efficiency (CUE). Our findings demonstrate that existing MAOC and saturation deficit, not microbial CUE, are key to determining new MAOC formation in agricultural soils.
Carbon mineralization to solid carbonates is one of the reaction pathways that can not only utilize captured CO 2 but also potentially store it in the long term. In this study, the dissolution and carbonation behaviors of alkaline solid wastes (i.e., waste concrete) was investigated. Concrete is one of the main contributors to a large carbon emission in the built environment. Thus, the upcycling of waste concrete via CO 2 utilization has multifaceted environmental benefits including CO 2 emission reduction, waste management and reduced mining. Unlike natural silicate minerals such as olivine and serpentine, alkaline solid wastes including waste concrete are highly reactive, and thus, their dissolution and carbonation behaviors vary significantly. Here, both conventional acid (e.g., hydrochloric acid) and less studied carbonic acid (i.e., CO 2 saturated water) solvent systems were explored to extract Ca from concrete. Non-stoichiometric dissolution behaviors between Ca and Si were confirmed under far-from-equilibrium conditions (0.1 wt% slurry density), and the re-precipitation of the extracted Si was observed at near-equilibrium conditions (5 wt% slurry density), when the Ca extraction was performed at a controlled pH of 3. These experiments, with a wide range of slurry densities, provided valuable insight into Si re-precipitation phenomena and its effect on the mass transfer limitation during concrete dissolution. Next, the use of the partial pressure of CO 2 for the pH swing carbon mineralization process was investigated for concrete, and the results were compared to those of Mg-bearing silicate minerals. In the P CO 2 swing process, the extraction of Ca was significantly limited by the precipitation of the carbonate phase (i.e., calcite), since CO 2 bubbling could not provide a low enough pH condition for concrete–water–CO 2 systems. Furthermore, this study showed that the two-step carbon mineralization via P CO 2 swing, that has been developed for Mg-bearing silicate minerals, may not be viable for highly reactive Ca-bearing silicate materials (e.g., concrete). The precipitated calcium carbonate (PCC) derived from waste concrete via a pH swing process showed very promising results with a high CO 2 utilization potential as an upcycled construction material.
The need to diversify approaches to produce essential energy carriers such as H 2 motivate advances in thermodynamically downhill geo-inspired pathways. Currently, more than 80% of hydrogen is produced via steam methane reforming (SMR) followed by water gas shift reaction (WGSR) pathway with the co-production of CO 2 . As an alternative to introducing CO 2 separation strategies downstream such as the use of membranes, solvents, or sorbents, geo-inspired carbon mineralization is harnessed as an alternative crystallization pathway. The thermodynamically downhill carbon mineralization pathways are hypothesized to accelerate H2 conversion while separating CO 2 . The work conducted through this project discusses the mechanisms associated with coupling the water gas shift reaction (WGSR) with carbon mineralization. In addition to harnessing Ca- and Mg-bearing oxides or hydroxides that are known to be reactive for CO 2 capture, the use of earth abundant silicate minerals such as Ca- and Mg-bearing silicates, is also investigated. Key outcomes include approaches to architect Mg-silicate with well-controlled pore size distributions, probing the enhancement in H 2 yield with inherent CO 2 suppression using Ca- and Mg-bearing oxides, hydroxides, and silicates, elucidating the changes in silicate chemistry during carbon mineralization, and exploring direct integration of carbon mineralization with WGSR and the development of separate low temperature pathway for reactive CO 2 capture and mineralization are developed.
Marine and lacustrine carbonate minerals preserve carbon cycle information, and their stable carbon isotope values (δ 13 C) are frequently used to infer and reconstruct paleoenvironmental changes. However, multiple processes can influence the δ 13 C values of bulk carbonates, confounding the interpretation of these values in terms of conditions at the time of mineral precipitation. Co-existing carbonate forms may represent different environmental conditions, yet few studies have analyzed δ 13 C values of syndepositional carbonate grains of varying morphologies to investigate their origins. Here, we combine stable isotope analyses, metagenomics, and geochemical modeling to interpret δ 13 C values of syndepositional carbonate spherules (>500 μm) and fine-grained micrite (<63 μm) from a ~1600-year-long sediment record of a hypersaline lake located on the coral atoll of Kiritimati, Republic of Kiribati (1.9°N, 157.4°W). Petrographic, mineralogic, and stable isotope results suggest that both carbonate fractions precipitate in situ with minor diagenetic alterations. The δ 13 C values of spherules are high compared to the syndepositional micrite and cannot be explained by mineral differences or external perturbations, suggesting a role for local biological processes. We use geochemical modeling to test the hypothesis that the spherules form in the surface microbial mat during peak diurnal photosynthesis when the δ 13 C value of dissolved inorganic carbon is elevated. In contrast, we hypothesize that the micrite may precipitate more continuously in the water as well as in sub-surface, heterotrophic layers of the microbial mat. Both metagenome and geochemical model results support a critical role for photosynthesis in influencing carbonate δ 13 C values. The down-core spherule–micrite offset in δ 13 C values also aligns with total organic carbon values, suggesting that the difference in the δ13C values of spherules and micrite may be a more robust, inorganic indicator of variability in productivity and local biological processes through time than the δ 13 C values of individual carbonate forms.