CO2 Pressure Research Articles

Integrating Umpolung and CO2 Shuttling Strategies for the Synthesis of 12C- and 13C-α-Ketoacids from Aldehydes.

The direct carboxylation of aldehydes with CO2 is rare due to the polarity mismatch between these two electrophilic substrates. To address this challenge, we propose a sequential approach for synthesizing α-ketoacids from commercially available aldehydes by integrating umpolung and CO2 shuttling strategies. This transition metal-free shuttle carboxylation method enables the transfer of CO2 from triphenylacetic acid potassium salt to thioacetal, eliminating the need for handling pressurized CO2 gas or using specialized equipment, while also enhancing the reaction's functional group tolerance. Furthermore, the use of stoichiometric or slightly excess amounts of triphenylacetic acid potassium salt as a formal CO2 donor makes it suitable for complete 13C labeling of α-ketoacids.

A Green Chemo-Enzymatic Approach for CO2 Capture and Transformation into Bis(cyclic carbonate) Esters in Solvent-Free Media.

A sustainable approach for CO2 capture and chemo-enzymatic transformation into bis(cyclic carbonate) esters from CO2, glycidol, and organic anhydrides under solvent-free conditions has been demonstrated. The chemo-enzymatic process is based on two consecutive catalytic steps, which can be executed through separated operations or within a one-pot combo system, taking advantage of the synergic effects that emerge from integrating ionic liquid (IL) technologies and biocatalysts. In a first step, lipase-catalyzed transesterification and esterification reactions of different diacyl donors (e.g., glutaric anhydride, succinic anhydride, dimethyl succinate, etc.) with glycidol in solvent-free under mild reaction conditions (70 °C, 6 h) produce the corresponding diglycidyl ester derivatives in up to 41% yield. By a second step, the synthesis of bis(cyclic carbonate) esters was carried out as a result of the cycloaddition reaction of CO2 (from an exhausted gas source, 15% CO2 purity) on these diglycidyl esters, catalyzed by the covalently attached 1-decyl-2-methylimidazolium IL (supported ionic liquid-like phase, SILLP), in solvent-free condition, leading up to 65% yield after 8 h at 45 °C and 1 MPa CO2 pressure. Both key elements of the reaction system (biocatalyst and SILLP) were successfully recovered and reused for at least 5 operational cycles. Finally, different metrics have been applied to assess the greenness of the solvent-free chemo-enzymatic synthesis of bis(cyclic carbonate) esters here reported.

Ionic liquid catalysed synthesis of benzimidazolone from Ortho-Phenylenediamine in the presence of carbon dioxide as a carbonyl source under solvent free condition

In this study, we report synthesis of benzimidazolones from o-phenylene diamine by utilizing carbon dioxide as a carbonyl source under mild reaction conditions in the presence of ionic liquid as a catalyst. Six bifunctional protonic ionic liquids (PILs) were synthesised by reacting superbases 1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD) and 1,8-diazabicyclo-[5.4.0]undec-7-ene (DBU) with proton donors such as Trifluoroethanol (TFE), Cyclopropane carboxylic acid (CPCA) and 2,2,2-Trifluoroacetic acid (TFA). Among them, [TBDH+][TFE−] was the most effective, achieving high conversion rates of o-phenylene diamine to 2-benzimidazolone at 1 bar CO2 pressure and 60° C. This PIL could be reused for up to six cycles. Our method offers a green and efficient approach for producing 2-benzimidazolone derivatives, with potential applications in pharmaceuticals and materials science.

Dynamic wetting mechanism of coal under different CO2 pressure: A new analytical basis through T2 cutoff

The technology of injecting carbon dioxide into coal seams to reduce greenhouse gas emissions and has brought attraction on the wettability of coal. As a fast and non-destructive method, nuclear magnetic resonance (NMR) is widely used in the evaluation of coal wettability, but the inconsistency of analytical basis makes the quantitative evaluation of coal wettability changes uncertain. In this study, based on NMR combined with centrifugal experiments, a novel analytical basis using irreducible water defined by T2 cutoff value was proposed to quantitatively analyze the dynamic wetting mechanism under different CO2 pressures. The results show that when T2 < 72.32 ms, the water in coal is irreducible water; when T2 > 72.32 ms, the water in coal is movable water. CO2 pressure hindered free water conversion to adsorbed and capillary water, but impacted adsorbed water more. Increased CO2 pressure caused the wetting porosity of coal to decrease from 1.62 % to 1.08 %, and coal gradually changed from water-wet to CO2-wet. The increase in CO2 pressure enlarged the CO2 aggregations in the seepage channel, thus weakening the wetting rate of water to coal. CO2 preferentially occupied small pores, which will hinder the migration of water into small pore spaces. Molecular diffusion controls water to achieve wetting equilibrium more than gravity/pressure difference and capillary force. As CO2 pressure increases, the wetting equilibrium time decreases.

Fracture propagation characteristics of water and CO2 fracturing in continental shale reservoirs

Exploring the adaptability of CO2 and water-based fracturing to shale oil reservoirs is important for efficiently developing shale oil reservoirs. This study conducted fracturing experiments and acoustic emission (AE) monitoring on the Jurassic continental shale. Based on high-precision computed tomography scanning technology, digital reconstruction analysis of fracture morphology was carried out to quantitatively evaluate the complexity of fractures and the stimulation reservoir volume (SRV). The results show that the fracturing ability of a single water-based fracturing fluid is limited. Low-viscosity fracturing fluid tends to activate thin layers and has limited fracture height. High-viscosity fracturing fluid tends to result in a wide and simple fracture. A combination injection of low-viscosity and high-viscosity water-based fracturing fluid can comprehensively utilize the advantages of low-viscosity and high-viscosity fracturing fluids, effectively improving the complexity of fractures. CO2 fracturing is adaptable to Jurassic shale. The breakdown pressure of the supercritical CO2 (SC-CO2) fracturing is low. Branch fractures form, and laminas activate during SC-CO2 fracturing due to its high diffusivity. Under high-temperature and high-pressure conditions, the aqueous solution formed by mixing CO2 with water can promote the formation of complex fractures. Compared with water-based fracturing fluid, the complexity of fractures and effective stimulation reservoir volume (ESRV) increased by 8.7% and 47.6%, respectively. There is a high correlation between SRV and ESRV, and the proportion of AE shear activity is also highly correlated with the complexity of fractures. The results are expected to provide better fracturing schemes and effectiveness for continental shale oil reservoirs.

Experimental measurements and thermodynamic modeling of dissociation pressure of CO2 hydrate in sulfate solutions

Carbon capture and storage (CCS) has been a popular strategy to mitigate climate change and has attracted significant attention from both industry and academia. CO2 can be stored in the form of CO2 hydrate in deeper locations in an ocean, which makes it a potential option for CO2 sequestration. Dissolved salts in the ocean brine can significantly affect the dissociation pressure of CO2 hydrate. Sulfate salts are one of the most common salt species in the oceanic brine. Although various experimental studies have been conducted to investigate the phase behavior of CO2 hydrate in brine, few studies focus on the effect of sulfate salts on the dissociation pressure of CO2 hydrate. In this study, we build an in-house experimental setup to investigate the effect of monovalent and divalent sulfate salts on the dissociation pressure of CO2 hydrate. The dissociation pressure of CO2 hydrate in Na2SO4, K2SO4, MgSO4, and CuSO4 aqueous solutions is measured using the isochoric pressure search method at different concentrations over the temperature range of 274.36–––282.15 K and the pressure range of 1.50–––4.03 MPa. A hybrid methodology incorporating the Soave-Redlich-Kwong Equation of State (SRK EOS), the van der Waals-Platteeuw (vdW-P) model, and the Pitzer model is applied to predict the dissociation pressure of CO2 in sulfate solutions. In addition, the dissociation enthalpies of CO2 hydrate in these sulfate solutions are calculated using the Clausius-Clapeyron equation based on the measured dissociation points. The experimental results show that the dissociation pressure of CO2 hydrate in Na2SO4, K2SO4, and MgSO4 solutions is higher than that in pure water, and the dissociation pressure of CO2 hydrate in sulfate solutions increases with an increasing salt concentration. Conversely, CuSO4 barely affects the dissociation pressure of CO2 hydrate, which is mainly attributed to the lower molar concentration of the ions compared with the other salt solutions and the ion specificity of Cu2+. The prediction results are in alignment with the experimental data measured in this study, which proves the feasibility of the thermodynamic model in predicting the dissociation pressure of CO2 hydrate in sulfate solutions. Additionally, the calculated dissociation enthalpies of CO2 hydrate show a dependence on both temperature and salt concentration. It is also revealed that Cu2+ exhibits ion specificity in affecting the dissociation enthalpy of CO2 hydrate, likely due to its distinct ability to impact the cage occupancy of CO2 hydrate compared with the other ions. These findings enhance our understanding of the impact of sulfate salts on the dissociation behavior of CO2 hydrate and offer valuable insights for CO2 sequestration.

Geochemical modeling of diagenetic reactions between albitization of K-feldspar and plagioclase feldspar in sandstone reservoirs under the influence of CO2 partial pressure

Diagenetic albitization has been observed in sedimentary basins around the world. This process significantly changes the original composition of sandstones and the chemistry of the formation waters under the influence of partial pressure of CO2. The transformation of detrital feldspars into albite is considered a crucial diagenetic process in the Gulf Coast and North Sea reservoirs. Earlier studies suggest that plagioclase albitization typically happens before that of K-feldspar. In the Gulf Coast's Frio Sandstone, located in the Upper Oligocene at depths between 900 and 2400 m, detrital plagioclase is often dissolved and replaced by albite, while K-feldspar mostly dissolves without much substitution. Similarly, in the North Sea reservoirs, especially in the upper section of the Upper Triassic Lunde Formation at depths beyond 2900 m, plagioclase tends to undergo albitization, whereas K-feldspar remains largely unaffected or experiences minimal transformation. This research focuses on analyzing the differences in the albitization patterns of detrital and K-feldspar plagioclase through the KINDISP and Geochemist's Workbench (GWB) geochemical modeling tools, aiming to compare them. These diagenetic processes are crucial for reservoir geology, as they influence the concentration of silica in water, which, in turn, affects quartz cementation. This study aims to explore the variations in the albitization behavior of detrital and K-feldspar plagioclase using the KINDISP and Geochemist's Workbench (GWB) geochemical models and conduct a comparative analysis between them. Understanding these diagenetic reactions becomes relevant for reservoir geology analysis, as such phenomena control the aqueous silica concentration to some extent, which is consequently reflected in the quartz cementation. The dissolution of plagioclase and K-feldspar releases silica into the pore fluids. As the concentration of silica in the fluid increases, it leads to the precipitation of quartz as overgrowths on detrital quartz grains, a process known as quartz cementation. This was observed particularly in simulations involving temperature increases up to 150 °C, where the equilibrium between albite and anorthite was closely linked to the stability of quartz (Ben et al., 1993). The removal of feldspar through albitization reduces porosity and permeability but contributes silica to the system, which promotes quartz cementation. This, in turn, decreases the reservoir quality by filling pore spaces with secondary quartz, reducing the rock's ability to store and transmit fluids. Thus, the study highlights the importance of these diagenetic processes in reservoir evaluation, as the balance between feldspar dissolution and quartz cementation ultimately controls reservoir properties.

Investigation the Impact of Different Injection Agents on Tight Oil Reservoirs of Recovery Performance

Abstract Objectives/Scope: Due to strong water sensitivity and extremely low permeability, conventional water flooding method is not suitable for the Mahu Conglomerate reservoir. In response to the complex reservoir physical properties, different injection agents such as CO2, N2, water and air huff and puff injection were carried out in order to optimize injection parameters for enhanced oil recovery in tight conglomerate reservoirs. Methods, Procedures, Process: By means of NMR, scanning electron microscopy, energy spectrum, pore fluids state in different media after different agents displacement were studied. Displacement and CT testing on different media and post fracturing state were conducted. Through experiments on on-site cores from two different layers, three different injection media (H2O, N2, CO2 and air with different O2 concentration) were tested for enhanced oil recovery. Then, the injection process was performed under different injection pressures. Finally, multiple cycles of enhanced oil recovery tests were conducted corresponding optimal injection pressures. Results, Observations, Conclusions: The remaining oil in the pores is mainly in free and bound states, with a free state of approximately 58% and a bound state of approximately 42%. Four pressures were selected for this test based on the minimum miscibility pressure of CO2 with crude oil: 15MPa, 20MPa, 23MPa, and 25MPa. The recovery factor under different pressures is 6.44%, 8.14%, 10.31%, and 10.38%, respectively. As the huff and puff pressure increases, the recovery of CO2 huff and puff gradually increases, and the increase of recovery is insignificant when the mixture pressure is reached. The gas flooding process involves oil production from large and submicron pores first. As the displacement pressure difference increases, oil production from large pores decreases, with medium pores becoming the main force of oil production, while oil production from nanoscale micropores shows an increasing trend. The increase in oxygen content results in significant development of sub-micron micron scale pores. The gas breakthrough time is long, the capillary force decreases, and air can undergo low-temperature oxidation with crude oil, resulting in an overall oil displacement efficiency of 65.81%. Novel/Additive Information: At present, there is few research on the pore fluid flow and status of oil displacement in tight conglomerate reservoirs with different injection media. This study provides a good understanding of the submicron to nanoscale pore throat structure characteristics of tight oil reservoirs, revealing the state of pore fluids in gravel after displacement by different injection media, and providing support for on-site application of CO2 enhanced oil recovery in tight conglomerate oil reservoirs.

Association of dynamic changes in arterial partial pressure of carbon dioxide with neurological outcomes in aneurysmal subarachnoid hemorrhage

BackgroundCerebral blood flow (CBF) is closely regulated by carbon dioxide (CO2). In patients with aneurysmal subarachnoid hemorrhage (aSAH), abnormal arterial partial pressure of CO2 (PaCO2) might deteriorate brain injuries. Nevertheless, the impact of dynamic PaCO2 fluctuations on neurological outcomes in aSAH patients has not been extensively studied. Our study aimed to investigate the association between dynamic PaCO2 levels and unfavorable neurological outcomes in aSAH patients. MethodsIn this retrospective observational study, we consecutively enrolled 159 aSAH patients from December 2019 to July 2021. Arterial blood gas measurements within 10 days after intensive care unit (ICU) admission for each patient were recorded to calculate the time-weighted average (TWA)-PaCO2, an indicator representing the dynamic changes in PaCO2 levels. For the association between TWA-PaCO2 levels and unfavorable neurological outcomes in aSAH patients, multivariable logistic analysis was used to explore TWA-PaCO2 levels as categorical variables, and restricted cubic spline (RCS) was used to explore TWA-PaCO2 levels as continuous variables. ResultsIn multivariable logistic analysis, after adjusting confounders, when TWA-PaCO2 35–45 mmHg was as a reference, TWA-PaCO2 < 35 mmHg (odds ratio [OR] 2.15, 95 % confidence interval [CI] 0.83–5.55, P = 0.113) and TWA-PaCO2 > 45 mmHg (OR 8.31, 95 % CI 0.72–96.14, P = 0.090) were not independently associated with unfavorable neurological outcomes (modified Rankin score of 3–6). The RCS shows a “U” shape curve between TWA-PaCO2 levels and unfavorable neurological outcomes, with a nonlinear P-value of 0.023. The lowest ORs of unfavorable neurological outcomes were within PaCO2 32.8–38.1 mmHg. ConclusionsBoth lower and higher PaCO2 levels are harmful to aSAH patients. PaCO2 in the range of 32.8–38.1 mmHg is associated with lowest unfavorable neurological outcomes.

Groundwater-derived carbon stimulates headwater stream CO2 emission potential on the Qinghai-Tibet Plateau

CO2 emissions from headwater streams are a crucial component of greenhouse gas flux in inland waters. However, the influence of groundwater, a major contributor to streams in the Asian Water Tower (Qinghai-Tibet Plateau, QTP), on CO2 levels remains unclear. This study employed stable isotope analysis and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to demonstrate that groundwater-derived dissolved inorganic carbon (DIC) significantly enhances CO2 supersaturation in the Shuiluo stream on the QTP. Specifically, the partial pressure of CO2 (pCO2), indicative of CO2 emission potential, increased more than threefold to 1,615 ± 495 μatm in groundwater-rich sites, nearly one time higher than the mean value (843 μatm) across the QTP. Groundwater-derived carbonate weathering had a significant impact of 76.6% on the increased pCO2, whereas the degradation of highly unsaturated polyphenolics with high O/C contributed to a decrease of 15.8%. The estimated inflow of groundwater-derived DIC could reach 9.59 ± 0.34 Tg C/y in total runoff across the QTP, highlighting significant CO2 sources. This study presents new findings on the effects of groundwater-derived DIC on stream CO2 emissions in weathered regions and expands our knowledge of fluvial CO2 emission on the QTP.

Pcv-aCO2/Ca-cvO2 Combined with Optic Nerve Sheath Diameter in Predicting Elevated Intracranial Pressure of Patients with Traumatic Brain Injury in Prehospital Setting.

To investigate a correlation between the central venous minus arterial CO2 pressure to arterial minus central venous O2 content ratio (Pcv-aCO2/Ca-cvO2) combined with optic nerve sheath diameter (ONSD) in predicting prehospital elevated intracranial pressure (ICP) in traumatic brain injury (TBI) patients. This was a prospective observational study of all adult TBI patients from the surgical intensive care unit who underwent invasive ICP monitoring between January 2023 and December 2023. Using a Delica MVU-6300 machine with 14-5 MHz linear probe to measure ONSD. We drew blood samples for arterial and central venous blood gases to measure and calculate the following indicators such as Pcv-aCO2, Ca-cvO2, and Pcv-aCO2/Ca-cvO2 ratio. ONSD and Pcv-aCO2/Ca-cvO2 were recorded during the first 3 days after admission. Simultaneous ICP values were gained from the invasive monitoring. Associations between ONSD, Pcv-aCO2/Ca-cvO2 and simultaneous ICP were explored by Spearman correlation analysis. We constructed an ROC curve to identify the ONSD and Pcv-aCO2/Ca-cvO2 cutoff for the evaluation of elevated ICP. We included 54 patients aged mean 57.13 (standard deviation 4.02) years and 24 (44%) were male. A significant correlation was observed between ONSD and ICP (r = 0.74, P < 0.01). The AUC was 0.861 (95% CI: 0.727-0.951), with a best cutoff value of 5.62 mm. Using a cutoff of 5.62mm, ONSD had a sensitivity of 92.8%, specificity of 80.4%. The Pcv-aCO2/Ca-cvO2 ratio also significantly correlated with ICP (r = 0.70, P < 0.01). The AUC was 0.791 (95% CI: 0.673-0.889). The optimal Pcv-aCO2/Ca-cvO2 value for predicting elevated ICP was 1.98mmHg/mL. Using a cutoff of 1.98mmHg/mL, Pcv-aCO2/Ca-cvO2 had a sensitivity of 87.3%, specificity of 77.2%. The AUC for ONSD combined with Pcv-aCO2/Ca-cvO2 was 0.952 (95% CI: 0.869-0.971), which had a sensitivity of 95.1%, specificity of 93.9%. Pcv-aCO2/Ca-cvO2 combined with ONSD performed best in predicting elevated intracranial pressure of patients with TBI in a prehospital setting. Our findings provide a crucial tool to improve earlier management of these patients in prehospital care, where the availability and utilization of invasive monitoring is limited. It could lead to significant changes in how TBI patients are monitored and treated before reaching a hospital.

Construction of hollow core-shell ZnO@Co3O4 p-n heterojunction for CO2 cycloaddition under visible light irradiation

In comparison to a single semiconductor, constructing p-n heterojunctions represents an efficient strategy for enhancing photocatalytic activity because of their advantages in accelerating charge separation and promoting photoabsorption. Herein, we propose a novel metal–organic framework (MOF)-assisted and controlled pyrolysis strategy for constructing a hollow core-shell p-n heterojunction photocatalyst ZnO@Co3O4. It is worth noting that the hollow core-shell heterojunction not only provides abundant active sites but also significantly facilitates the separation of photogenerated charge carriers and accelerates electron transfer. Benefiting from the above advantages, the optimized ZnO@Co3O4(400,2), obtained by pyrolysis at 400 ℃ for 2h using Zn-MOF@Co-MOF as a precursor, exhibits high activity for the cycloaddition of CO2 and epichlorohydrin, resulting in a 94% yield of 4-(chloromethyl)-1, 3-dioxolan-2-one under 1bar CO2 pressure and visible light irradiation for 2h, which is significantly superior to those of ZnO(400,2) (5%), Co3O4(400,2) (38%), and the physically mixed counterparts (55%). This work provides insightful guidance for designing efficient photocatalysts aimed at CO2 cycloaddition, thereby achieving solar to high-value-added chemical conversion efficiencies.

Incorporation of Mg/Al metal oxide into ionic liquids for CO2 capture and conversion into cyclic carbonate under solvent-free conditions: Effect of coordination ability, recyclability, and catalytic study

The direct conversion of carbon dioxide (CO2) and propylene oxide (PO) into propylene carbonate (PC) offers a green way to utilize anthropogenic CO2. However, this reaction is limited by low conversion of PO and harsh reaction conditions. In this study, we solve this problem using ionic liquids (ILs)/metal oxide composites (ILs@MAO). The catalytic activity of MAO-500 (500 = annealing temperature) is poor evidenced by its low conversion of PO (24.94%). However, ILs@MAO-500 has a high conversion of PO (97.54%) under similar reaction conditions (2 h at 1.5 MPa CO2 pressure, 90 °C, and 0.85 g catalyst). The ILs consist of imidazolium cation with weak coordinated [NTf2]– anion leading to outward movement of anion resulting in the formation of “heterodinuclear complex”. This complex generates an amorphous-crystalline intermediate with balanced acid-base sites that activate PO and stabilize the catalytic intermediate. In large part, the high PO conversion is theorized to be primarily due to the abundant reactive sites in the ILs that are covalently immobilized on the MAO-500 carrier. Furthermore, even after multiple recycling, ILs@MAO-500 remains stable and exhibits high yield and selectivity. The proposed solvent-free catalytic system is mild, kinetically fast, and naturally safe for coupling CO2 and PO into PC synthesis.

Mononuclear phenoxy-imine Mg(II) compounds as catalysts for the ring-opening copolymerization of epoxides with CO2

The ring-opening copolymerization (ROCOP) of epoxides with CO2 is an efficient gateway for synthesizing sustainable aliphatic polycarbonates. The demand for the use of biocompatible metals for the copolymerization is an appealing research goal. The oxophilic Mg(II) has been employed as a metal center in homodinuclear and heterodinuclear catalyst frameworks. However, there is scarce literature involving mononuclear Mg(II) compounds. This work investigates the catalytic activity of two series of phenoxy-imine containing mononuclear Mg(II) compounds for the copolymerization studies of epoxides with CO2 in conjugation with cocatalyst tetraphenylphosphonium chloride (TPPCl). The two series of Mg(II) compounds differed from each other in the number of ancillary ligands attached to the Mg(II) center. The two epoxides employed for the study include cyclohexene oxide (CHO) and propylene oxide (PO). The catalytic activity of the disubstituted Mg(II) compounds was higher compared to monosubstituted compounds. In addition, the dependence of catalytic activity and percentage of carbonate linkage with the variation in the substituent of the phenolate core and imine side arm were studied. At 40 bar CO2 pressure and 80 °C, the catalyst exhibited carbonate linkage up to 97 % for ROCOP with cyclohexene oxide (CHO) with the percentage of the highest m-centered tetrad reaching up to 94 %. The mechanism for the ROCOP of CHO with CO2 is proposed based on kinetics studies and experimental data, which is further supported by density functional theory-based calculations.

Enhanced CO2 Hydrogenation Performance of CoCrNiFeMn High Entropy Alloys

CO2 hydrogenation is a promising process for removing anthropogenic CO2 emissions and yielding C1 chemicals that can be utilized as fuels and valuable precursors for chemical synthesis. Commercial high-entropy alloys (HEAs) have widespread application in various fields owing to their exceptional thermal stability and tunable microstructure. However, their potential application as catalysts is often limited by the low exposure of active sites. In this study, the commercial CoCrNiFeMn powder was applied for atmospheric pressure CO2 hydrogenation and enhanced its catalytic performance by a combined treatment of ball milling and high-temperature H2 reduction. The high-energy ball milling results in a morphological transition in CoCrNiFeMn HEAs from spherical to irregular. This transformation leads to a significant decrease in particle size and more surface reactive sites. The high-temperature H2 reduction promoted the atomic rearrangement on the CoCrNiFeMn surface, thereby improving its alloy structural homogeneity. These modifications greatly improve the performance of CoCrNiFeMn for CO2 hydrogenation. This work introduces a facile modification approach to facilitate the catalytic efficiency of commercial HEAs in CO2 hydrogenation with high selectivity.

Molecular Dynamics Study on the Storage of Carbon Dioxide in Single-Walled Carbon Nanotubes at Low Pressures.

The storage of carbon dioxide (CO2) in single-walled carbon nanotubes was studied with molecular dynamics simulation. The influences of the temperature, system average density, and nanotube size on the CO2 pressure, density distribution, and intermolecular forces were investigated. Multilayer adsorption inside nanotubes was observed as average density increases at lower pressures, which is desirable in industry. Meanwhile, a nanobubble was gradually formed in the center of the nanotube, and the system with the nanobubble was stabilized by the balance between the positive Laplace pressure and the negative liquid pressure when the size of the nanobubble was higher than the critical size. The adsorption effect of the nanotube wall leads to high local condensed density near the wall and stronger intermolecular repulsion, while Laplace pressure results in a low local condensed density in the adsorbed CO2 near the bubble interface and stronger intermolecular attraction. The stretching effect that originates from the intermolecular force dominated by attraction in the condensed phase leads to low pressure. At the critical nanobubble size, a higher CO2 average density can be achieved by lowering the temperature and increasing the nanotube radius or length. When the adsorption impact of the nanotube wall on bubble destabilization becomes negligible as the adsorption layer thickens, further increasing the nanotube radius leads to limited increase of the average density at the critical nanobubble size. The simulation of a graphene-sealed nanotube confirmed the formation of a vapor nanobubble under more realistic conditions. This work provides insights into utilizing carbon nanotubes as a material for CO2 capture with multilayer adsorption at lower pressures.

Elevated pCO2 may increase the edible safety risk of clams exposed to toxic Alexandrium spp.

Toxic harmful algal blooms (HABs) have received increasing attention owing to their threat to the health of aquatic life and seafood consumers. This study evaluated the impacts of elevated atmospheric partial pressure of CO2 (pCO2) on the production of paralytic shellfish toxins (PSTs) in different Alexandrium spp. strains, together with its further effects on the bioaccumulation/elimination dynamics of PSTs in bivalves contaminated with PSTs from toxic dinoflagellates. Our results showed that elevated pCO2 stimulated the growth of the two Alexandrium spp. (A. catenella and A. pacificum) isolated from the northern and southern coastal areas of China, respectively, and affected PST production including content and toxicity of the two strains differently. Further PSTs bioaccumulation/elimination in PSTs-contaminated Manila clam, Ruditapes philippinarum under high pCO2 also occurred. It is worth noting the biotransformation of neosaxitoxin (NEO) with high toxicity through trophic transfer with effect of elevated pCO2. When in microalgae cultured under the control (410 ppm) and elevated pCO2 conditions (495 and 850 ppm), the proportion of NEO in the PST content produced by A. catenella was reduced from 11.1 to 6.4 and 2.6 %, while the proportion of NEO in A. pacificum was increased from 3.1 to 3.6 and 4.7 %, respectively. NEO accounted for >50 % of total PST contents in clams, which were biotransformed via transfer from dinoflagellates and higher pCO2 enhanced this biotransformation leading to increased NEO accumulation. The negatively affected elimination of PSTs, especially NEO, in clams fed with A. catenella or A. pacificum, indicates that the detoxification of PSTs-contaminated clams may be more difficult under elevated pCO2. This study provides reference for developing models to assess the safety of bivalves under the co-stress of environmental change and toxic HABs, suggesting that ocean acidification may lead to the higher safety risk of Manila clams exposed to toxic HAB dinoflagellates.

Feasibility of carbon dioxide geological storage in abandoned coal mine: A fully coupled model with validated multi-physical interactions

It has gained wide attention that Carbon dioxide (CO2) is to be injected into abandoned coal mines for geological storage of CO2-enhanced coalbed methane recovery. Although abundantly evidences in literature indicate that the injection of CO2 will cause lots of interactions among the mechanical characteristics of coal and the properties of CO2 flow, further studies on these multi-physical interactions are still necessary. In this work, a series of laboratory experiments to elucidate the multi-physical interactions of CO2 adsorption, softening effect of coal and the non-Darcy gas flow were conducted. Based on the experimental results, theoretical and empirical models to describe these coal-CO2 interactions were meticulously proposed and validated, the results turned out to be satisfactory. Consequently, the compressive strength and elasticity modulus of coal decrease exponentially with the increased injection CO2 pressure. The gas flow in coal obeys the Izbash non-Darcy model, and coal permeability can be well modified by the volumetric stress. By taking these coal-CO2 interactions into account, this study established of a fully coupled model for coal deformation and CO2 conservation. The model was then implemented into the numerical simulations of CO2 storage in abandoned coal mine by using the finite element method. A series of scenario-based numerical simulations was conducted to investigate the feasibility and limitation of CO2 storage in abandoned coal mine. The conducted experiments, models and numerical simulation will offer implications on the multi-physical interactions between coal and gas especially in CO2 storage in abandoned coal mines.

Investigation of clinical and paraclinical consequences of tramadol poisoning and related factors

Tramadol, is frequently misused and leading to an increase in cases of overdose and poisoning worldwide. This study aimed to investigate the clinical and paraclinical consequences of tramadol poisoning and related factors. This was a retrospective study performed on patients with acute tramadol poisoning who were referred to the Amir Al-Momenin Hospital Emergency Department, Zabol, during 2019-2020. Patients’ socio-demographic information and clinical and paraclinical manifestations were collected in a predesigned checklist. Overall, 71 subjects were included in this study. The mean dose of tramadol was 640.14 ± 521 mg. Seizures occurred in 17 subjects that were not dose-dependent. In patients who died or were in a coma, pH, bicarbonate (HCO3 ), and oxygen saturation (O2 sat) levels decreased, while PCO2 levels increased significantly (P &lt; 0.05). The dose of tramadol used in the poisoning of this substance played no role in the course of the disease and the prognosis of patients, but low pH, HCO3 , O2 sat, and high CO2 pressure could be related to the outcome of these patients.

Interfacial properties of CO2 and liquid sulfur in high-sulfur gas fields: Molecular simulations on carbonate mineral surfaces

As the global energy landscape transforms, the development of high-sulfur natural gas has become increasingly critical. However, sulfur deposition during these gas field developments significantly affects operational efficiency. This study employed molecular dynamics simulation to explore the effectiveness of CO2 in alleviating sulfur deposition on carbonate rock reservoirs. Specifically, it examined the interfacial tension between liquid sulfur and CO2, the wettability of sulfur on carbonate rock mineral surfaces, and the kinetics of CO2 displacing liquid sulfur. Results show that as CO2 pressure increases from 10 MPa to 60 MPa, the interfacial tension between liquid sulfur and CO2 decreases by 84 %, from 35.54 mN/m to 5.53 mN/m. The contact angles of sulfur droplets on calcite and dolomite surfaces stabilize at 41.82° ± 2.10° and 44.33° ± 3.27°, respectively, indicating greater sulfur spread on calcite surfaces. With higher CO2 pressures, sulfur deposition on mineral surfaces and interfacial tension both decrease significantly, while the wetting angle of liquid sulfur increases, particularly on dolomite. At 60 MPa CO2 pressure, the adsorption energy of dolomite for liquid sulfur drops from 364.56 kcal/mol to 25.46 kcal/mol, a 93 % reduction, suggesting CO2′s dual role in displacing sulfur and promoting its desorption from mineral surfaces. Furthermore, the efficiency of sulfur deposition alleviation in carbonate rock slit structures improves and stabilizes at around 40 MPa CO2 pressure. This study presents a potential environmentally friendly approach for efficiently developing high-sulfur gas fields, and its findings provide practical insights for optimizing CO2 injection strategies to mitigate sulfur deposition.