CO2 Absorption Research Articles

Excess Properties, FT-IR Spectral Analysis, and CO2 Absorption Performance of Monoethanolamine with Diethylene Glycol Monoethyl Ether or Methyldiethanolamine Binary Solutions.

In this study, densities and viscosities of the binary solutions of monoethanolamine with diethylene glycol monoethyl ether or methyldiethanolamine were determined at 293.15, 298.15, and 303.15 K and p = 100.5 kPa. The experimental density data were tested with different equations as a function of composition (Belda and Herraez equations) and as a function of temperature and composition (Emmerling et al. and Gonzalez-Olmos-Iglesias equations). The results show that the Herraez and Emmerling et al. equations best correlate the experimental data. The experimental values of viscosity were tested with different models based on one, two, three, or four parameters. The values of excess molar volume (VE), viscosity deviation (Δη), and excess Gibbs energy (ΔG*E) were calculated from the experimental values and were fitted to the polynomial equations. The values of the excess molar volume are negative for both systems, while positive values were obtained for the viscosity deviation and excess Gibbs activation energy. The values of thermodynamic functions of activation of viscous flow were determined and discussed. The Fourier transform infrared spectroscopy (FT-IR) spectra of the binary solutions analyzed in this study enabled the understanding of the interactions among the molecules in these solutions. In addition, the CO2 absorption capacity of the binary solutions of monoethanolamine with diethylene glycol monoethyl ether or methyldiethanolamine was determined experimentally.

Optimization and Analysis of CO2 Capture in RPB using Cognitive Computing and Evolutionary Algorithm

Due to industrialization, deforestation and many other anthropogenic activities, carbon emission is increasing at a rate of approximately at a rate of 1% in past few years. Now, reduction of atmospheric carbon dioxide (CO2) has become a significant concern and challenge for every country across the globe. This paper is a sincere effort to study, analyse and further optimize, amine based post-combustion carbon (PCC) capture. Monoethanolamine (MEA) in rotating packed beds (RPB) has been extensively studied for CO2 chemical absorption. Enhancing CO2 capturer efficiency necessitates a thorough comprehension of the complex interrelationships within the key parameters. This study focuses on modelling and optimisation of CO2 absorption efficiency in MEA by artificial intelligence and genetic algorithms (GA). Machine learning (ML) and Artificial Neural Networks (ANN) are versatile instruments employed to model and forecast diverse complex and highly non-linear phenomena. The established process models have been established by published steady-state experimental data. Subsequently, SHAP analysis has been applied that reveals the input factors such as solvent concentration, flow rate, and rotational speed are the primary determinants of CO2 absorption in RPB. To assess the model's performance, the acquired results have been examined using statistical measures, including MSE, RMSE, and R2 value. The modelling results have been utilised to optimise CO2 absorption, employing GA under various operating conditions to ascertain the optimal values for the input variables that correlate to maximized CO2 capture.

Advancement in modification of polyvinylindene fluoride hollow fiber membrane contactors for CO2 capture

Abstract Membrane contactors are well-designed, environmentally friendly, waste free technology which have been of great interest in area of gas separations. Polyvinylidene fluoride (PVDF) is promising membrane contactor material characterized with high hydrophobicity, high solubility in wide range of solvents and good chemical resistance. In spite of the viability and merits, key intrinsic issue with PVDF membranes contactor is membrane wetting that consequently results in increase in mass transfer-resistance, membrane flux deteriorations and decline in overall long-term stability performances. Different modification methods and strategies that involve alterations of surface chemistry and structures have been identified to mitigate wetting issue. The intention of modification tactics is to enhance surface’s hydrophobicity of PVDF contactor membranes thereby controlling membrane wetting. This review presents the approaches previously adopted for PVDF membranes modifications. The progresses besides performances of the modified PVDF membranes in area of gas separations are discussed. Lastly, challenges in addition to outlooks of modified PVDF membrane for membranes contactor were highlighted. This review has brought into limelight the methods and the justifications for PVDF membrane modifications geared towards effective performances of PVDF membranes contactors for CO2 absorption.

Simulation studies of the solvent diethylamine for post-combustion CO2 capture at the WACEM cement manufacturing plant in southern Togo at Tabligbo

Industrial CO2 emissions continue to rise despite global reduction efforts, driving climate change and global warming. Post-combustion carbon capture using aqueous diethylamine (DEA) is a promising strategy to mitigate these emissions. This study aims to simulate CO2 absorption from the Western African Cement (WACEM) industry’s flue gases using the Hysplit model. The tray column's key parameters, the gas-liquid mixture's thermophysical properties, and the treated emissions' composition were investigated. Results indicate optimal CO2 absorption occurs when the flue gas mass flow rate does not exceed 12.5% of the liquid mixture entering the column. The process is most effective at a DEA flow rate of 250 L/h, with a furnace temperature of 160°C and a pressure of 17 bars. These findings provide valuable insights for policymakers and industry stakeholders in optimizing post-combustion carbon capture for emission reduction.

A JWST Panchromatic Thermal Emission Spectrum of the Warm Neptune Archetype GJ 436b

Abstract GJ 436b is the archetype warm Neptune exoplanet. The planet’s thermal emission spectrum was previously observed via intensive secondary eclipse campaigns with Spitzer. The atmosphere has long been interpreted to be extremely metal-rich, out of chemical equilibrium, and potentially tidally heated. We present the first panchromatic emission spectrum of GJ 436b observed with JWST’s NIRCAM (F322W2 and F444W) and MIRI (LRS) instruments between 2.4 and 11.9 μm. Surprisingly, the JWST spectrum appears significantly fainter around 3.6 μm than that implied by Spitzer photometry. The molecular absorption features in the spectrum are relatively weak, and we only find tentative evidence of CO2 absorption at 2σ. Under the assumption of a dayside blackbody, we find T day = 662.8 ± 5.0 K, which is similar to the zero Bond albedo equilibrium temperature. We use it to obtain a 3σ upper limit on the Bond albedo of A B ≤ 0.66. To understand the spectrum, we employ 1D radiative–convective models but find that atmospheric constraints depend strongly on model assumptions. If thermochemical equilibrium is assumed, we find a cloudy metal-enriched atmosphere (metallicity ≥300× solar). We employ 1D photochemical modeling to show that the observed spectrum is also consistent with a cloud-free, relatively lower metallicity atmosphere (metallicity ≥80× solar) with a cold internal temperature (T int ∼ 60 K). These are much lower metallicities and internal temperatures than inferences from Spitzer photometry. The low T day and nondetection of transmission features at high spectral resolution do suggest a role for cloud opacity, but this is not definitive.

THERMOPHYSICAL ASPECTS FOR SUSTAINABLE NON-AQUEOUS AMINE SOLVENTS CONTAINING IONIC LIQUIDS IN CO2 CAPTURE PROCESS

<p>Climate change is a prime threat to human health and the environment. Carbon dioxide (CO2) emissions play a pivotal role in global warming, the greenhouse gas effect, destroys the ecosystem. This impact of climate change can be prevented with the help of a solvent-based CO2 absorption process. In this study, amine-ionic Liquids (IL) were used as a solvent blend for the CO2 absorption process. The non-aqueous solvent blend Monoethanolamine (MEA) - Ionic Liquid (IL) namely tetrabutylammonium hexafluorophosphate [TBA][PF6] and their total concentration was kept at 30 wt% throughout the study. The thermophysical properties such as density, dynamic viscosity, surface tension, pH and carbon loading of virgin and carbon-loaded non-aqueous amine-IL have been measured before and after the absorption process experimentally. This study was extensively carried out for varying temperatures (293.15 to 333.2 K) and IL concentration (1-2 wt%) at intervals of 10 K and 0.5 wt% respectively.  All the measured thermophysical properties of amine-IL show a significant increase in the IL concentration. Conversely, it declines while increasing temperature. Higher carbon loading was observed for 2wt% IL+28wt% MEA, compared to 30wt% MEA, even though increased viscosity was obtained at this composition. This non-aqueous amine-IL solvent might favor sustainable development in CO2 capture process.</p>

JWST-TST High Contrast: Living on the Wedge, or, NIRCam Bar Coronagraphy Reveals CO2 in the HR 8799 and 51 Eri Exoplanets’ Atmospheres

Abstract High-contrast observations with JWST can reveal key composition and vertical mixing dependent absorption features in the spectra of directly imaged planets across the 3–5 μm wavelength range. We present novel coronagraphic images of the HR 8799 and 51 Eri planetary systems using the NIRCam Long Wavelength Bar in an offset “narrow” position. These observations have revealed the four known gas giant planets encircling HR 8799, even at spatial separations challenging for a 6.5 m telescope in the mid-infrared, including the first ever detection of HR 8799 e at 4.6 μm. The chosen filters constrain the strength of CO, CH4, and CO2 absorption in each planet’s photosphere. The planets display a diversity of 3–5 μm colors that could be due to differences in composition and ultimately be used to trace their formation history. They also show stronger CO2 absorption than expected from solar metallicity models, indicating that they are metal enriched. We detected 51 Eri b at 4.1 μm and not at longer wavelengths, which, given the planet’s temperature, is indicative of out-of-equilibrium carbon chemistry and an enhanced metallicity. Updated orbits fit to the new measurement of 51 Eri b validate previous studies that find a preference for high eccentricities ( e = 0.5 7 − 0.09 + 0.03 ), which likely indicates some dynamical processing in the system’s past. These results present an exciting opportunity to model the atmospheres and formation histories of these planets in more detail in the near future, and are complementary to future higher-resolution, continuum-subtracted JWST spectroscopy.

A Review of Materials for Carbon Dioxide Capture

The increasing concentration of carbon dioxide (CO2) in the atmosphere is a significant contributor to global warming and climate change. Effective CO2 capture and storage technologies are critical to mitigating these impacts. This review explores various materials used for CO2 capture, focusing on the latest advancements and their applications. The review categorizes these materials into chemical and physical absorbents, highlighting their unique properties, advantages, and limitations. Chemical absorbents, such as amine-based solutions and hydroxides, have been widely used due to their high CO2 absorption capacities and established technological frameworks. However, they often suffer from high energy requirements for regeneration and potential degradation over time. Recent developments in ionic liquids (ILs) and polymeric ionic liquids (PILs) offer promising alternatives, providing tunable properties and lower regeneration energy. Physical absorbents, including advanced solvents like nanofluids and ionic liquids as well as industrial processes like selexol, rectisol, and purisol, demonstrate enhanced CO2 capture efficiency under various conditions. Additionally, adsorbents like activated carbon, zeolites, metal-organic frameworks (MOFs), carbon nanotubes (CNTs), and layered double hydroxides (LDHs) play a crucial role by providing high surface areas and selective CO2 capture through physical or chemical interactions. This paper summarizes the state of research on different materials and discusses their advantages and limitations while being used in CO2 capture technologies. This review also discussed multiple studies examining the use of catalysts and absorption mechanisms in combination with different sorbents, focusing on how these approaches enhance the efficiency of absorption and desorption processes. Through a comprehensive analysis, this review aims to provide valuable insights into the type of materials that are most suitable for CO2 capture and also provides directions for future research in this area.

Effect of Diethanolamine after Carbon Dioxide Absorption and Desorption on Mechanical Strength of Cement Mortar and Mechanism.

Diethanolamine (DEA) can be used not only as a cement admixture but also to capture carbon dioxide (CO2). However, the waste liquid treatment still faces the problems of high energy consumption and increasing environmental burden. The effects of DEA waste liquid (WL-DEA) with multiple cycles of CO2 absorption and desorption on the setting time, hydration temperature, mechanical strength, and microstructure of cement-based materials were explored. It was found that adding WL-DEA could significantly reduce the setting time and enhance the mechanical strength. This improvement was mainly attributed to two aspects: on the one hand, alcoholamine itself could boost cement hydration, which could accelerate the generation of hydration products such as AFt/AFm, CH, C-A-S-H, and C-S-H, thereby improving the cement early strength and refining the microstructure of hydration products; on the other hand, WL-DEA contained little CO32- and HCO3-, which reacted with Ca2+ to produce CaCO3. The above reactions cooperated with the complexation effect of WL-DEA to further promote hydration and optimize densification of the hydration products. The application of WL-DEA in cement-based materials could not only effectively enhance their mechanical strength but also promote the recycling of waste liquid, which provided a new method for promoting the development of a circular economy.

Phase Change-Mediated Capture of Carbon Dioxide from Air with a Molecular Triamine Network Solid.

The efficient removal of CO2 from exhaust streams and even directly from air is necessary to forestall climate change, lending urgency to the search for new materials that can rapidly capture CO2 at high capacity. The recent discovery that diamine-appended metal-organic frameworks can exhibit cooperative CO2 uptake via the formation of ammonium carbamate chains begs the question of whether simple organic polyamine molecules could be designed to achieve a similar switch-like behavior with even higher separation capacities. Here, we present a solid molecular triamine, 1,3,5-tris(aminomethyl)benzene (TriH), that rapidly captures large quantities of CO2 upon exposure to humid air to form the porous, crystalline, ammonium carbamate network solid TriH(CO2)1.5·xH2O (TriHCO2). The phase transition behavior of TriH converting to TriHCO2 was studied through powder and single-crystal X-ray diffraction analysis, and additional spectroscopic techniques further verified the formation of ammonium carbamate species upon exposing TriH to humid air. Detailed breakthrough analyses conducted under varying temperatures, relative humidities, and flow rates reveal record CO2 absorption capacities as high as 8.9 mmol/g. Computational analyses reveal an activation barrier associated with TriH absorbing CO2 under dry conditions that is lowered under humid conditions through hydrogen bonding with a water molecule in the transition state associated with N-C bond formation. These results highlight the prospect of tunable molecular polyamines as a new class of candidate absorbents for high-capacity CO2 capture.

The study on the adsorption characteristics of anthracite under different temperature and pressure conditions.

The study of the adsorption characteristics of coal is of great significance to gas prevention and CO2 geological storage. To explore the adsorption mechanism of coal, this study focuses on columnar anthracite. Adsorption tests on coal rock under a range of physical field conditions were conducted using the volumetric method. The adsorption characteristics of anthracite for CO2, CH4, and N2 gases under different conditions were investigated using Grand Canonical Monte Carlo (GCMC) and Molecular Dynamics (MD) methods. The results showed that the adsorption capacities of anthracite for these three gases are in the order of CO2 > CH4 > N2, and that the adsorption capacity increases with increasing gas injection pressure. The CO2/CH4/N2 gas molecule adsorption capacity of the anthracite macromolecular structure model decreases with increasing temperature. The increase in temperature has the greatest influence on the CO2 absorption capacity, followed by the CH4 and N2 adsorption capacities. The research offers a theoretical basis for the control of coal mine gas and the geological storage of CO2.

Effects of bubble behavior on CO2 absorption into [emim][AcO]/sulfolane solution in honeycomb fractal microchannel

Abstract The honeycomb fractal structure is an efficient mass and energy transportation system. In this study, the influences of IL concentration of absorbent and operating conditions on the gas–liquid two‐phase flow characteristics and CO2 absorption performance were visually investigated in a honeycomb fractal microchannel. Five flow patterns were observed: non‐breakup and non‐coalescence, non‐breakup and coalescence, breakup and non‐coalescence, breakup and coalescence, and unstable flow regimes. As bubble coalescence is inconducive to CO2 absorption efficiency, the criterion for predicting bubble coalescence was proposed to prevent its occurrence. The distribution of bubbles in the microchannel was characterized by introducing the asymmetry factor and gas holdup, and it was found that the two parameters are closely related to the flow pattern. The influences of the operating condition, flow pattern, and physical property of the absorbent on CO2 absorption were studied systematically, and an effectively predictive correlation of CO2 absorbed fraction was obtained.

Spatio-Temporal Variability in CO2 Fluxes in the Atlantic Sector of the Southern Ocean

The Southern Ocean (SO) plays a fundamental role in the planet’s climate system, due to its ability to absorb and redistribute heat and CO2 (an important greenhouse gas). In addition, the SO connects three large oceanic basins the Pacific, the Atlantic, and the Indian Oceans, and it has an important role in the nutrient distribution in these oceans. However, the SO is poorly sampled, with most measurements made in austral spring and summer. The variability in the air–sea CO2 flux is estimated, as well as the role of atmospheric and oceanic variables in this variability. The CO2 fluxes are calculated using the bulk parameterization method, in the Atlantic sector of the Southern Ocean, from 2003 to 2022, using in situ measurements, satellites, and a reanalysis data set. A neural network model is built to produce maps of the partial pressure of CO2 in seawater (pCO2sea). The CO2 flux varies from −0.05 to 0.05 gC m−2 month−1. The Atlantic sector of the SO is a sink of CO2 in summer and spring and becomes a source in austral winter and autumn. The CO2 absorption intensifies from 2003 to 2022 by 7.6 mmol m−2 month−1, due to stronger westerly winds, related to the trend in the positive phase of the Antarctic Oscillation and the extreme El Niño Southern Ocean (ENSO) events (e.g., El Niño and La Niña).

Analysis of CO2 Absorption in Gas/Liquid Membrane Contactors with Inserted Descending Hydraulic Diameters of 3D-Printed Turbulence Promoters.

The decline in absorption flux across membrane modules is attributed to the increase in concentration polarization resistance in flat-plate membrane contactors for CO2 absorption using monoethanolamine (MEA) as the absorbent. Researchers have discovered that this effect can be mitigated by inserting turbulence promoters, which enhance turbulence intensity at the cost of increased power consumption, thereby improving CO2 absorption flux. The performance of flat-plate membrane contactors for CO2 absorption was further enhanced by reducing the hydraulic diameters of embedded 3D-printed turbulence promoters, considering the increased power consumption. The mass-balance modeling, incorporating chemical reactions, was developed theoretically and conducted experimentally on a flat-plate gas/liquid polytetrafluoroethylene/polypropylene (PTFE/PP) membrane module in the present study. A one-dimensional theoretical analysis, based on the resistance-in-series model and the plug-flow model, was conducted to predict absorption flux and concentration distributions. An economic analysis was also performed on modules with promoter-filled channels, considering different array configurations and geometric shapes of turbulence promoters, weighing both absorption flux improvement and power consumption increment. Device performances were evaluated and compared with those of modules using uniform promoter widths. Additionally, the Sherwood number for the CO2 membrane absorption module was generalized into a simplified expression to predict the mass transfer coefficient for modules with inserted 3D-printed turbulence promoters. Results showed that the ratio of absorption flux improvement to power consumption increment in descending hydraulic-diameter operations is higher than in uniform hydraulic-diameter operations.

Enhancing CO2 Fixation in Microalgal Systems: Mechanistic Insights and Bioreactor Strategies.

Microalgae are small, single-celled, or simple multicellular organisms that contain Chlorophyll a, allowing them to efficiently convert CO2 and water into organic matter through photosynthesis. They are valuable in producing a range of products such as biofuels, food, pharmaceuticals, and cosmetics, making them economically and environmentally significant. Currently, CO2 is delivered to microalgae cultivation systems mainly through aeration with CO2-enriched gases. However, this method demonstrates limited CO2 absorption efficiency (13-20%), which reduces carbon utilization effectiveness and significantly increases carbon-source expenditure. To overcome these challenges, innovative CO2 supplementation technologies have been introduced, raising CO2 utilization rates to over 50%, accelerating microalgae growth, and reducing cultivation costs. This review first categorizes CO2 supplementation technologies used in photobioreactor systems, focusing on different mechanisms for enhancing CO2 mass transfer. It then evaluates the effectiveness of these technologies and explores their potential for scaling up. Among these strategies, membrane-based CO2 delivery systems and the incorporation of CO2 absorption enhancers have shown the highest efficiency in boosting CO2 mass transfer and microalgae productivity. Future efforts should focus on integrating these methods into large-scale photobioreactor systems to optimize cost-effective, sustainable production.

The promotion mechanism of ethylene glycol on the absorption and desorption performance of CO2 in ethanolamine hydrochloride based deep eutectic solvents

The promotion mechanism of ethylene glycol on the absorption and desorption performance of CO2 in ethanolamine hydrochloride based deep eutectic solvents

Simulation study on the flow and mass transfer processes of CO2 absorption by co-current flow of amine droplets and microbubbles

Simulation study on the flow and mass transfer processes of CO2 absorption by co-current flow of amine droplets and microbubbles

Study of the CO2 absorption with K2CO3 sorbents in gas-solid fluidized beds based on second-order moment model

Study of the CO2 absorption with K2CO3 sorbents in gas-solid fluidized beds based on second-order moment model

The structure–activity relationship for CO2 absorption heat of chain diamines: Effects of amino types, methyl/ethyl groups, and chain lengths

The structure–activity relationship for CO2 absorption heat of chain diamines: Effects of amino types, methyl/ethyl groups, and chain lengths

Hot Rocks Survey I: A possible shallow eclipse for LHS 1478 b

Context. M-dwarf systems offer an opportunity to study terrestrial exoplanetary atmospheres due to their small size and cool temperatures. However, the extreme conditions imposed by these host stars raise a question about whether their close-in rocky planets are able to retain any atmosphere at all. Aims. The Hot Rocks Survey aims to answer this question by targeting nine different M-dwarf rocky planets spanning a range of planetary and stellar properties. Of these, LHS 1478 b orbits an M3-type star, has an equilibrium temperature of Teq = 585 K, and receives 21 times Earth’s instellation. Methods. We observed two secondary eclipses of LHS 1478 b using photometric imaging at 15 µm using the Mid-Infrared Instrument on the James Webb Space Telescope (JWST MIRI) to measure thermal emission from the dayside of the planet. We compared these values to atmospheric models to evaluate potential heat transport and CO2 absorption signatures. Results. We find that a secondary eclipse depth of 138 ± 53 ppm at the expected time for a circular orbit is preferred over a null model at 2.8σ, a moderate detection, though dynamical models do favour a non-eccentric orbit for this planet. The second observation results in a non-detection due to significantly larger unexplained systematics. Based on the first observation alone, we can reject the null hypothesis of the dark (zero Bond albedo) no atmosphere bare rock model with a confidence level of 3.3σ, though for AB = 0.2 the significance decreases to 2.1σ. The tentative secondary eclipse depth is consistent with the majority of the atmospheric scenarios we considered, spanning CO2-rich atmospheres with surface pressures from 0.1 to 10 bar. However, we stress that the two observations from our programme do not yield consistent results, and more observations are needed to verify our findings. The Hot Rocks Survey serves as a relevant primer for future endeavours such as the Director’s Discretionary Time (DDT) Rocky Worlds programme.