CO2 Absorption Research Articles

Development of nanoemulsion CO2 absorbents in an impinging stream rotating packed bed reactor

Development of nanoemulsion CO2 absorbents in an impinging stream rotating packed bed reactor

Thermal oxidation degradation mechanism under the rust-catalyzed condition of CO2 absorbent monoethanolamine and the DFT analysis of pathway

Thermal oxidation degradation mechanism under the rust-catalyzed condition of CO2 absorbent monoethanolamine and the DFT analysis of pathway

Characteristics of Carbon Sink and the Influencing Factors in Ngoring Lake, Qinghai‐Tibet Plateau

Abstract Continuous annual carbon dioxide (CO2) flux, encompassing ice‐covered periods, has been monitored in Ngoring Lake, the largest freshwater lake on the Qinghai‐Tibet Plateau (QTP). By utilizing continuous eddy system data, the characteristics and mechanisms influencing CO2 flux at various temporal scales in the lake were investigated. Findings revealed that Ngoring Lake was predominantly acting as a carbon sink year‐round. The average annual CO2 sink value was maximum in 2016, about −1.46 g C m−2 d−1. There were two CO2 absorption peaks in spring and autumn, respectively. The multi‐year average monthly mean CO2 absorption peaks occurred in April (−1.70 g C m−2 d−1) and October (−1.75 g C m−2 d−1), respectively. These peaks were associated with the freeze‐thaw process and were caused by the mixing process due to water cooling. The continuous warming during the ice‐covered period led to a high‐water temperature, and the maximum value reached 6°C. In spring, mixing occurred upon ice melt, and the water temperature at 2 m depth decreased rapidly to 4°C because it was about 5°C higher than the air temperature. In autumn, cooling and mixing were induced by decreasing air and water temperatures alongside strong wind. These cooling processes facilitated significant CO2 absorption. The CO2 absorption process was controlled by wind speed, lake ice, lake mixing and stratification.

Carbon-Negative Production of Soda Ash: Process Development and Feasibility Evaluation.

Aiming to produce carbon-negative soda ash, chlor-alkali electrolysis, CO2 direct air capture, and sodium carbonate crystallization are combined in a so-called CODA process. In this study, four variants of the CODA process are developed and evaluated by means of modeling and simulation. Variations of the process design are related with the CO2 absorption technology, the crystallization strategy, and the possible byproducts of the process. The processes using a cross-flow packed absorber had a smaller CAPEX (between 195 and 209 USD/ton soda) than the process using a droplet absorber (337 USD/ton soda). When coupled with the cross-flow packed absorber, the two-step crystallization strategy had a smaller OPEX (150 USD/ton soda) than the one-step crystallization (175 USD/ton soda). The revenue of selling the process byproducts such as hydrogen, chlorine, and CO2 certificates was key to the profitability of the CODA process. The most promising CODA variant (cross-flow packed absorber and two-step crystallization) consumes about 0.15 tons of CO2 from the air and earned nearly 200 USD/ton soda ash, making CODA an attractive alternative that deserves to be scaled-up.

PARAMETERISATION OF CORAL STRESSORS IMPACTING REEF ECO- MORPHODYNAMICS

Anthropogenic climate change is dramatically changing the geometry of coral reefs which has implications for shoreline protection, island formation and ecological stability (Vila‐Concejo and Kench, 2017). By 2100 global mean temperature is predicted to rise a further 0.5oC (4.8oC) and sea level a further 27(67) cm based on RCP scenarios 2.6 (8.5) (IPCC, 2023). Warmer temperatures will increase the frequency of storms and cyclones, which can mechanically disturb coral communities. At the same time, ocean pH will continue to decline due to greater CO2 absorption (IPCC, 2023), leading to losses in coral reef calcification and structural resilience. Due to the narrowing window of coral recover time resulting from a greater frequency and intensity of disturbances, there is a growing concern that coral reefs will undergo a phase shift towards algae-dominated reefs (Tebbett et al., 2022). Due to the ability to attenuate waves, corals play a crucial role in regulating the hydrodynamic energy within reefs. Consequently, phase-shifted reefs will diminish the potential for the coastal protection service that healthy reefs provide. Furthermore, reefs dominated by algae lack the sediment-forming potential seen in coral-dominated reefs, thereby influencing the stability and formation of islands.

Mechanisms of CO2 Absorption in Amino Acid-BasedDeep Eutectic Solvents: Insights from Molecular Dynamics and DFT Calculations

This study explores the mechanisms of CO2 absorptionin two amino acid-containing deep eutectic solvents (DESs) throughmolecular dynamics (MD) simulations and density functional theory(DFT) calculations. The MD simulations, which focus mainly on physicalabsorption, reveal that alanine-based DES (Ala DES) exhibits higherCO2 solubility than l-arginine-based DES (l-arg DES), attributed to stronger physical absorption. Furthermore,the hydrogen bond donor paired with the amino acids is identifiedas a critical factor for enhancing physical absorption efficiency.DFT calculations, which account for chemical absorption, investigatetwo reaction pathways: single-molecule reactions involving intramolecularproton transfer and two-molecule reactions involving intermolecularproton exchange. While Ala DES does not exhibit spontaneous chemicalabsorption, l-arg DES demonstrates such reactions, leadingto the formation of carbamic acid or carbamate (ΔG < 0), indicative of CO2 capture through chemical interactions.Consequently, Ala DES primarily relies on physical absorption, whereas l-arg DES utilizes multiple reactive sites for chemical absorption.These results are consistent with experimental findings, which showthat l-arg DES achieves higher CO2 solubilityunder atmospheric conditions. Overall, our study highlights the interplaybetween DES components and reactivity in enhancing CO2 captureefficiency.

Prediction of CO2 absorption in aqueous 1DMA2P solutions using thermodynamics and molecular dynamic simulations

Abstract This study employs thermodynamic methods and molecular dynamics simulations to predict the CO2 absorption capacity, reaction free energies, and densities in aqueous solutions of 1‐dimethylamino‐2‐propanol (1DMA2P). By combining quantum chemical calculations and classical molecular dynamics with optimized force field parameters, the model accurately predicts solution densities, pH values, and CO2 absorption properties. The results show significant non‐ideal behavior in 1DMA2P solutions during CO2 absorption, demonstrating the reliability of the developed model for predicting reaction equilibria and absorption performance, thus providing theoretical support for carbon capture technologies.

Unraveling natural carbonate variability in Narragansett Bay, RI using multiple high temporal resolution pH time series

The increase in atmospheric carbon dioxide (CO2) over the last 200 years has largely been mitigated by the ocean’s function as a carbon sink. However, this continuous absorption of CO2 by seawater triggers ocean acidification (OA), a process in which water becomes more acidic and more depleted in carbonate ions that are essential for calcifiers. OA is well-studied in open ocean environments; however, understanding the unique manifestation of OA in coastal ecosystems presents myriad challenges due to considerable natural variability resulting from concurrent and sometimes opposing coastal processes—e.g. eutrophication, changing hydrological conditions, heterogeneous biological activity, and complex water mass mixing. Developing a mechanistic understanding of carbonate chemistry variability and its drivers across different time scales is a critical first step in identifying the anthropogenic OA signal against background variability and predicting future OA in coastal systems. This study analyzed high temporal resolution pH data collected during 2022 and 2023 from Narragansett Bay, RI—a mid-sized, urban estuary that since 2005 has undergone a 50% reduction in nitrogen loading—with weekly, discrete bottle samples to verify sensor data. Over a year’s worth of data revealed a distinct diurnal cycle of pH, with pH increasing during the day and decreasing during the night, with an average daily range between 0.05 and 0.1 pH units. Further, we observed a strong seasonal cycles with higher mean pH in winter (8.07 ± 0.15) and lower mean pH in summer (7.72 ± 0.07). By separating the drivers of pH variability into effects from temperature, salinity, water mass mixing, biological activity, and air-sea gas flux, we determined that biological production has the most significant influence on pH from daily to annual timescales and in episodic pH changes. To a lesser extent, the seasonal air-sea CO2 exchange and temperature cycle further modified pH on monthly to seasonal timescales. The dominant influence of biological activity in modulating pH has allowed Narragansett Bay’s nutrient reductions, which have been successful in increasing bottom water DO and pH conditions, to modestly reduce summertime surface pH through reduced primary production. This study offers an in-depth understanding of Narragansett Bay’s natural carbonate variability and highlights the sensitivity of an estuary to water management policy. These findings will benefit future OA prediction and will ultimately assist in making environmental management decisions in coastal estuaries with implications for multiple coastal stakeholders.

Glycine and Boric Acid Promoted Accelerated Weathering of Limestone (AWL) Process for CO2 Absorption

Abstract The accelerated weathering of limestone (AWL) process is an efficient, cost-friendly, and eco-friendly CO2 capture technology. However, the low bicarbonate content measured as alkalinity of its produced effluent can cause up to 50% of its captured CO2 to re-enter the atmosphere within one year. To remedy this limitation, this study investigates the use of promoters (i.e., glycine and boric acid) in increasing the reactivity of the AWL process to elevate the effluent’s alkalinity. This work includes the correlation analysis and optimization analysis for promoted AWL to determine the optimum pH and promoter concentration. The correlation analysis revealed that increasing promoter concentration and pH enhance the effluent’s bicarbonate concentration. Based on the established correlation, the design of experiment (DoE) software with a two-level-two-factor central composite configuration was utilized to optimize the process. It was determined that the optimized glycine-promoted condition of 0.27 M and pH 11.52 achieved a maximum bicarbonate concentration of 53,200 mg/L as CaCO3 with an enhancement factor of 652. As for the boric acid-promoted AWL process, the highest bicarbonate concentration achieved was 42,100 mg/L as CaCO3, with an enhancement factor of 525 at 0.50 M and a pH of 11.84. In addition, the regeneration potential of the promoters via the addition of Ca(OH)2 was investigated. It was found that up to 49.68% of glycine can be regenerated, while an approximately 9% regeneration efficiency of colemanite (raw material of boric acid) was achieved. Overall, the study demonstrates the potential of using promoters to improve CO2 capture efficiency in the AWL process, with both glycine and boric acid showing promising results under optimized conditions.

3D Concrete Printing of Triply Periodic Minimum Surfaces for Enhanced Carbon Capture and Storage

Abstract Concrete, the world's second most utilized material after water, is responsible for 8% of global greenhouse emissions. Current carbon capturing and storage (CCS) concrete often involves convoluted processes, slow kinetics, limited CO2 uptake, non‐uniform carbonation in structures, and high cost. Efforts to enhance carbon sequestration often rely on increasing porosities, which compromise the mechanical strength of the resulting concrete. The 3D printing of CCS concrete is reported by incorporating diatomaceous earth (DE), a highly accessible biomineral with hierarchical porosity, into triply periodic minimal surface (TPMS) structures. DE enables stable extrusion, high print fidelity, and reduced density, which are crucial for 3D concrete printing. Further, DE facilitates CaCO3 nucleation within the concrete and mitigates carbonation resistance, achieving a maximum CO2 absorption of 488.7 gCO2 per kg cement in 7 days, a 142% increase over conventional concrete. Optimizing TPMS geometry further enhances carbonation efficiency by enabling uniform CO2 uptake throughout the structure. This geometry refinement reduces material usage by 78% and increases the surface‐area‐to‐volume ratio by 515%, leading to a 30% higher CO2 uptake while preserving mechanical integrity. The material strategy, together with the optimized concrete printing of TPMS structures, offers a pathway toward scalable and sustainable solutions without undermining concrete's structural functions.

Colossal permittivity and humidity sensing properties of CaCu3Ti4O12 ceramics derived from cockle shell CaCO3 via CO2 absorption

Cockle shells served as a sustainable and non-toxic calcium source for CO2 capture through carbonation–calcination cycles. In this study, CaCO3 derived from cockle shells was used to synthesize CaCu3Ti4O12 (CCTO) ceramics via the solid-state reaction method and sintered at 1010–1090 °C. The resulting ceramics exhibited colossal dielectric permittivity (∼ 105 at 1 kHz, 25 °C) and a low dielectric loss (tanδ ≈ 0.04), confirming their suitability for capacitor applications. The high dielectric permittivity was primarily attributed to the internal barrier layer capacitor mechanism, in which insulating grain boundaries separated semiconducting grains, enhancing interfacial polarization. Impedance spectroscopy supported this explanation, while DC bias-dependent dielectric measurements revealed a noticeable decrease in permittivity under applied voltage, indicating that surface barrier layer capacitor effects at the ceramic–electrode interface also contributed to the dielectric behavior. Furthermore, X-ray photoelectron spectroscopy confirmed the presence of oxygen vacancies and hydroxyl groups at the ceramic surface, which facilitated water molecule adsorption and modulated interfacial charge transport. As a result, the CCTO ceramics demonstrated excellent humidity sensing performance, with a fast response time of 0.25 min, a recovery time of 0.45 min, and a low hysteresis error of 2.3%. These findings demonstrate the dual role of cockle shell-derived CaCO3 as both a sustainable CO2 sorbent and a valuable precursor for high-performance dielectric and humidity-sensing ceramics.

Tracing the formation and migration history: molecular signatures in the atmosphere of misaligned hot Jupiter WASP-94Ab using JWST NIRSpec/G395H

Abstract The discovery of hot Jupiters that orbit very close to their host stars has long challenged traditional models of planetary formation and migration. Characterising their atmospheric composition — mainly in the form of the carbon-to-oxygen (C/O) ratio and metallicity — can provide insights into their formation locations and evolution pathways. With JWST we can characterise the atmospheres of these types of planets more precisely than previously possible, primarily because it allows us to determine both their atmospheric oxygen and carbon composition. Here, we present a JWST NIRSpec/G395H transmission spectrum from 2.8 – 5.1 µm of WASP-94Ab, an inflated hot Jupiter with a retrograde misaligned orbit around its F-type host star. We find a relatively cloud-free atmosphere, with absorption features of H2O and CO2 at detection significances of ∼4σ and ∼11σ, respectively. In addition, we detect tentative evidence of CO absorption at ∼3σ, as well as hints of sulphur with the detection of H2S at a ∼2.5σ confidence level. Our favoured equilibrium chemistry model determines a C/O ratio of $0.49^{+0.08}_{-0.13}$ for WASP-94Ab’s atmosphere, which is substellar compared to the star’s C/O ratio of 0.68 ± 0.10. The retrieved atmospheric metallicity is similar to the star’s metallicity as both are ∼2 × solar. We find that this sub-stellar C/O ratio and stellar metallicity can be best explained by pebble accretion or planetesimal accretion in combination with large-distance migration of the planet.

Influences of Diamine Molecular Structures on the Phase‐Change CO2 Capture From Flue Gas

ABSTRACTThe amino groups and its substituents of organic amine absorbents have an important influence on the CO2 absorption and desorption performance. In this study, four diamines with the same primary amino group and another different amino groups were selected as absorbents, including 1,3‐propanediamine (1,3‐PDA), 3‐methylaminopropylamine (MAPA), 3‐dimethylaminopropylamine (DMAPA), and 3‐diethylaminopropylamine (DEAPA). The phase‐change absorption system uses a mixture of polyether and H2O as the solvent. The CO2 absorption performance of flue gas was studied with the analysis on absorption and desorption rate, cycle capacity, and desorption ratio. The effect of diamine molecular structures on phase‐change CO2 capture was investigated by nuclear magnetic carbon spectroscopy. The results show that DEAPA exhibits highest absorption capacity of 1.21 mol CO2/mol amine and recycling capacity of 1.09 mol CO2/mol amine. The absorption rate of primary and secondary diamines in the phase‐change system is significantly higher than that of primary and tertiary diamines. The diamine system with tertiary amino groups has significantly faster desorption rate, higher desorption ratio, and cycle capacity than the primary and secondary diamine systems. The intramolecular tertiary amino group is more conducive to promoting the absorption of CO2 than the intermolecular tertiary amino group, which can increase the absorption rate of CO2 by the primary amino group and enhance the CO2 desorption.

CO2 Absorption on Cu-Doped Graphene, a DFT Study

We studied the interaction between a Cu-doped graphene layer and a CO2 molecule, using DFT, ab initio calculations, and the pseudopotential formalism. We used the Quantum ESPRESSO code package, with the PBE XC functional expression and the semiempirical Grimme’s DFT-D3 Van der Waals correction. We found that the Cu atom, being absorbed in a C vacancy on the graphene surface, has a catalytic effect on the absorption of CO2 in said surface. The Van der Waals correction calculations showed that the CO2 is physisorbed, with an adsorption energy of −0.1786 eV. Our results are congruent with previously published results. The Cu-doped graphene surface could be suitable for the development of a CO2 sensor.

Prediction of CO2 Solubility in Ionic Liquids Based on Machine Learning and Analysis of SHAP

The combination forms of anions and cations in Ionic liquids (ILs) which was solvent for the absorption of CO2 were extremely numerous. Consequently, a Machine Learning (ML) model of Transformer was used to measure the solubility of CO2 in each new ILs in this study. The model used 8869 data points and encoding anions and cations based on SMILES. The r, R2, RMSE and MAE were used as error indicators. Additionally, a decoding method was referenced for the first time in the field of ML predictions of CO2 solubility in ILs, which improved the data processing results. As a result, the model achieved better predictive standards. SMILES based SHAP analysis was used on the model to understand the black box operation. The results of the SHAP analysis identified the structural factors that influenced the model's results in the solubility of CO2 in ILs.

PERAN RUANG TERBUKA HIJAU DALAM MITIGASI PERUBAHAN IKLIM - SOSIALISASI DAN PELATIHAN BAGI AMGPM DI DESA LATUHALAT KOTA AMBON

Green open spaces (RTH) are public areas that play a strategic role in climate change itigation, particularly as CO2 absorbers and O2 producers, microclimate regulators, urban pollution reducers, and creators of thermal comfort for urban communities. However, the lack of knowledge and awareness among the public has led to the neglect of RTH existence. People remain trapped in improper RTH waste management practices, contributing to greenhouse gas emissions that exacerbate global warming. This community service activity is an educational effort aimed at enhancing public knowledge, improving skills, and correcting improper RTH management practices. The activities include socialization on the role of RTH in climate change mitigation, training on RTH waste management, and a collective tree-planting initiative. The series of activities is expected to raise public awareness about the importance of maintaining and protecting RTH as a safeguard in climate change mitigation. Additionally, it aims to foster collective actions within the community to contribute to saving the planet.

Thermal Performance, Energy and Environmental Assessment of Bamboobased Panels from Industrial Wastes for Low Carbon Buildings

Insulation is one of the most effective methods for reducing energy consumption in both the heating and cooling of buildings. Selecting the right materials is crucial as, in addition to reducing emissions from the operation phase thanks to high energy efficiency, it is important that innovative materials also have a low impact during the production process. A growing interest focuses on the replacement of synthetic insulations with recycled materials. Among these are by-products from industrial transformation and manufacturing, residues from agro-industrial processes, and farming wastes. Natural materials have substantially less embodied energy than processed materials, so their use in new buildings and refurbishments can make a worthwhile contribution to sustainability. In this scenario, bamboo is an abundant and promising source. Its ability to capture CO2 from the atmosphere, enhanced by its rapid growth, makes it an ally in mitigating climate change and GHG emissions. To sustain its CO2 absorption capacity, bamboo requires regular harvesting. A valuable application of bamboo prunings is in the production of furniture and textiles. Furthermore, due to its exceptional strength-to-weight ratio and resistance to moisture and insects, bamboo is well-suited for manufacturing durable structural components and building materials, particularly in humid climates. This, however, results in a considerable amount of waste generated at various stages of the bamboo life cycle. This work aims to reduce construction environmental impacts using vegetal waste collected from the different phases of bamboo processing to produce monosheet thermoinsulating panels. Bamboo was characterized, milled to the particle size of 1.397 mm and incorporated into the adhesive. As low-impact alternatives to synthetic glues, two vegetal glues were used, specifically cellulose-based, selected based on polymer hydrophobicity and water solubility when dry, influencing the samples’ permeability. Preparation and drying procedure was developed and preliminary tests identified the optimal mixtures which balance mechanical strength and minimum adhesive. 9 circular samples (φ=100 mm) 40 mm thick were prepared mixing bamboo grains with 3 types of glue (vinyl glue, methyl cellulose, 4 % CMC), each used in 3 different concentration levels (50 %, 75 %, 85 %). Thermal conductivity of the panels was experimentally evaluated by C-Therm TCi thermal analyser according to ASTM D7984. Energy saving potential of the best solution was compared to that of commercial synthetic panels through dynamic simulations on a case study building in central Italy. The environmental impact of the new component was assessed through a ‘Cradle to Gate’ LCA. The optimal vegetal glue combination is the 85 %-one. It was observed that for higher densities, the thermal properties worsen. Considering the production phase, the innovative panel’s embodied energy is over 20 % lower than that of traditional insulation material.

Inverted Microdroplets (Microbubbles) Induced Interfacial Water Protonation to Promote Alkaline Release of Amine and Reduce Energy in CCS.

This study engineered a superacidic interface with a pronounced polar electric field within the amine-water system by inducing hydrogen bond charge transfer in interfacial water via inverted microdroplets (microbubbles), thereby stabilizing protons within the interfacial water layer. This mechanism enabled the continuous alkaline release of hindered amines (AMP-MIS), enhancing CO2 absorption load capacity and reducing regeneration energy consumption. Nuclear magnetic resonance and potentiometric titration elucidated the product distribution, while Raman spectroscopy, pH analysis, and conductivity measurements confirmed proton stabilization. Theoretical calculations provided insights into the reaction mechanism. Pilot-scale testing revealed the AMP-MIS system achieved a 74.2% increase in CO2 cyclic load capacity, surpassing the conventional 30 wt % MEA system, with regeneration energy reduced from 3.667 GJ/t CO2 to 1.885 GJ/t CO2. This innovative strategy offers valuable guidance for advancing amine-based decarbonization technologies and reducing carbon emissions in the power industry, representing a pivotal step toward carbon neutrality.

Revisiting the Group-dominant Elliptical NGC 5044 in the Radio Band: Continuum Emission and Detection of H i Absorption

Abstract We present new MeerKAT L-band (continuum and H i) and upgraded Giant Metrewave Radio Telescope (300–850 MHz) observations of the archetypal cool-core group-dominant early-type galaxy NGC 5044. Our new continuum images reveal diffuse, steep spectrum ( α 0.99 GHz 1.56 GHz = − 1.53 ± 0.6 ) radio emission extending about 25 kpc around the unresolved radio core. The observed radio emission overlaps the known X-ray cavities but is not confined to them. We also find the first direct evidence of neutral atomic gas in NGC 5044, in the form of a 3.8σ significant two-component H i absorption line seen against the emission of the active nucleus. The peak velocities are well correlated with the previously reported CO(2–1) absorption, but the H i lines are moderately broader, spanning velocities from 265 to 305 km s−1. We do not detect H i emission but place an upper limit of M H i &lt; 5.4 × 107 M ⊙in the central 15″ (2.2 kpc) of the galaxy. This is significantly less than the estimated molecular gas content and implies a molecular-to-atomic mass ratio of &gt;∼1.7:1, consistent with these gas phases forming through cooling from the hot intra-group medium. We also constrain the spin temperature to T spin ≤ 950 K, indicating that the detected H i is in the cold neutral phase.

Gas Endeavour: An Innovative Equipment for Estimating Methane Kinetics During In Vitro Rumen Fermentation.

The growing need to reduce methane emissions from ruminants while enhancing feed utilization has driven the development of innovative in vitro measurement techniques. This review examines the Gas Endeavour (GES), an automated volumetric apparatus that quantifies both total gas and methane production in real time during rumen fermentation. Utilizing the principles of liquid displacement and buoyancy, the GES integrates a thermostatically controlled water bath, specialized gas flow cells, and an alkaline CO2 absorption unit to deliver precise kinetic data on fermentation. Compared to conventional methods-which often rely on manual measurements and post-incubation gas chromatography-the GES provides continuous monitoring and immediate data acquisition, reducing labour and potential errors. This review discusses the system's design, operational challenges such as controlling headspace pressure and ensuring consistent inoculum preparation, and its applications in both animal nutrition and biomethane potential assessments. The findings suggest that, with further standardization and protocol refinement, the GES could significantly advance research aimed at optimizing feed digestibility and mitigating methane emissions in ruminant production systems.