Cotransporter Research Articles

Predictive modeling of pH on the transport of Co(II) Ions from aqueous solutions through supported ceramic polymer membrane

Optimal pH is essential for efficient cobalt extraction from polymeric membrane systems, with D2EHPA used as an extractant for Co(II) at pH < 7, achieving 47% efficiency. The pH of piperazine as a stripping agent increases to a concentration of 0.48 M, and the extraction efficiency of Co(II) > 80%. Depending on the functional group of (C4H10N2), the optimal pH for separation was 9.8. The study revealed that pKa value was calculated to predict the ideal pH, and its value was 9.73, which is nearly to the pH, since the pH of the strip concentration and the properties of the membrane affect the extraction of cobalt at 30 °C. The partition ratio indicates the high distribution of the extract in supported ceramic polymer membrane (SCPM). The ceramic component provides mechanical strength and rigidity to the overall membrane structure, allowing it to withstand high pressures and temperatures during operation Study various factors such as the effect of pH on the ionization of the extract; effect of pH on band ionization; effect of pH on the temperature in the extract, effect of pH on the solute, effect of the band at different pH ranges and a comparison was made between the predictive model and experimental data that was proven through mathematical modeling using the MATLAB program.

Coupling CO2 Reduction and Acetyl-CoA Formation: The Role of a CO Capturing Tunnel in Enzymatic Catalysis.

The bifunctional CO-dehydrogenase/acetyl-CoA synthase (CODH/ACS) complex couples the reduction of CO2 to the condensation of CO with a methyl moiety and CoA to acetyl-CoA. Catalysis occurs at two sites connected by a tunnel transporting the CO. In this study, we investigated how the bifunctional complex and its tunnel support catalysis using the CODH/ACS from Carboxydothermus hydrogenoformans as a model. Although CODH/ACS adapted to form a stable bifunctional complex with a secluded substrate tunnel, catalysis and CO transport is even more efficient when two monofunctional enzymes are coupled. Efficient CO channeling appears to be ensured by hydrophobic binding sites for CO, which act in a bucket-brigade fashion rather than as a simple tube. Tunnel remodeling showed that opening the tunnel increased activity but impaired directed transport of CO. Constricting the tunnel impaired activity and CO transport, suggesting that the tunnel evolved to sequester CO rather than to maximize turnover.

Main current legal and regulatory frameworks for carbon dioxide capture, transport, and storage in the European Economic Area

There is broad consensus on the key role that carbon dioxide (CO2) capture, transport, and storage (CCTS) systems will play in mitigating climate change, either by removing CO2 from the atmosphere and storing it permanently or by avoiding CO2 emissions generated by point sources, especially from hard-to-abate sectors (e.g., waste-to-energy, cement, shipping or aviation). Although CCTS is ready to be implemented from a technical standpoint, the legal and regulatory framework required for its implementation and regulation could be further improved. In this article, we summarize and critically discuss the provisions of the Convention for the Protection of the Marine Environment of the North-East Atlantic (the ‘OSPAR Convention’), and of the London protocol, as well as of the European CCS and ETS Directives. With a focus on the European Economic Area, we highlight existing gaps and hurdles that should be tackled in view of the large-scale deployment of CCTS. Furthermore, as the legal landscape for CO2 transport and geological storage is evolving rapidly, we provide an overview of recent clarifications on aspects of the existing legislation and a summary of new proposals presented by the European Commission in this space.

Climate forcing controls on carbon terrestrial fluxes during shale weathering

Climate influences near-surface biogeochemical processes and thereby determines the partitioning of carbon dioxide (CO2) in shale, and yet the controls on carbon (C) weathering fluxes remain poorly constrained. Using a dataset that characterizes biogeochemical responses to climate forcing in shale regolith, we implement a numerical model that describes the effects of water infiltration events, gas exchange, and temperature fluctuations on soil respiration and mineral weathering at a seasonal timescale. Our modeling approach allows us to quantitatively disentangle the controls of transient climate forcing and biogeochemical mechanisms on C partitioning. We find that ~3% of soil CO2 (1.02 mol C/m2/y) is exported to the subsurface during large infiltration events. Here, net atmospheric CO2 drawdown primarily occurs during spring snowmelt, governs the aqueous C exports (61%), and exceeds the CO2 flux generated by pyrite and petrogenic organic matter oxidation (~0.2 mol C/m2/y). We show that shale CO2 consumption results from the temporal coupling between soil microbial respiration and carbonate weathering. This coupling is driven by the impacts of hydrologic fluctuations on fresh organic matter availability and CO2 transport to the weathering front. Diffusion-limited transport of gases under transient hydrological conditions exerts an important control on CO2(g) egress patterns and thus must be considered when inferring soil CO2 drawdown from the gas phase composition. Our findings emphasize the importance of seasonal climate forcing in shaping the net contribution of shale weathering to terrestrial C fluxes and suggest that warmer conditions could reduce the potential for shale weathering to act as a CO2 sink.

A probabilistic approach to optimal emergency shutdown valve configuration for pressurised CO2 pipelines

This study presents a multi-objective optimisation technique for determining the optimal number of in-line Emergency Shutdown Valves (ESDVs) for pressurised CO2 pipelines, aiming to balance risk associated with pipeline failure against the valve cost based on treating the risk as a probabilistic variable. Using standard Probability Density Functions (PDFs) to model the uncertainties inherent in pipeline characteristics and operating conditions, we perform a Monte Carlo simulation involving the random sampling from these PDFs to derive a probabilistic distribution of risk. This method contrasts with traditional deterministic methods that rely on assuming the worst-case failure scenario or pre-determining an averaged expected risk level — typically calculated by summing the products of failure frequencies and consequence magnitudes for various representative failure scenarios. The proposed approach integrates the risks of all possible failure scenarios directly into the optimisation process without such assumptions or pre-determinations, assessing them collectively based on their individual probabilities of occurrence. Our findings illustrate that the proposed technique allows for more reliable and effective ESDV configurations compared to the traditional methods. This approach not only facilitates safer CO2 transport within the context of Carbon Capture, Utilisation and Storage but also offers a framework for optimising pipeline ESDV configurations in general.

Investigation of Pipeline CO2 Leakage and Diffusion on Offshore Platforms Based on Numerical Simulation.

Pipeline transportation of CO2 is the key link to realize carbon capture, utilization, and storage. CO2 pipeline transportation may face the risk of leakage, which poses a great threat to the production process and personnel safety. It is of great significance to study the leakage and diffusion characteristics of CO2 in pipeline transportation for the safety design and personnel protection of the offshore CO2 storage platform. In order to study the leakage and diffusion characteristics of CO2 in pipeline transportation on offshore platforms, a physical model of a target platform and several numerical models were built, and a series of pipeline CO2 leakage and diffusion simulations were carried out using the method of numerical simulation. Based on the simulation results, the temperature distribution and CO2 concentration distribution on the offshore platforms after leakage were measured and analyzed. The influence of leakage direction (horizontal and oblique 45° upward) was also studied. Dangerous areas on the platform and suggestions for staff evacuation were given according to the simulation results. The research results of this work can provide guidance for the safe operation of offshore CO2 storage platforms.

Session 18. Oral Presentation for: Requalification of pipelines for CO2 transport – giving new life to the Bayu-Undan and Reindeer pipelines

Session 18. Oral Presentation for: Requalification of pipelines for CO2 transport – giving new life to the Bayu-Undan and Reindeer pipelines

Cost and environmentally efficient design of an absorption-based post-combustion carbon capture unit for industry applications

Carbon capture and storage technologies are currently considered promising solutions to mitigate CO2 emissions of hard-to-abate industries. Among those, the cement industry accounts alone for around 6–7 % of the global anthropogenic CO2 emissions and necessitates the integration of carbon capture and storage to substantially reduce its CO2 emissions. This work focused on the design and analysis of a cost-efficient and low-emitting cement plant integrated with an absorption-based Post-Combustion Carbon Capture (PCCC) system using an aqueous water-amine solution. An innovative system layout is presented to minimize CO2 emissions and energy consumption. Furthermore, the sizing of the absorber and stripper of the PCCC unit was performed to minimize the cost of the avoided CO2. The environmental and economic performances of the overall process are evaluated under different boundary conditions, encompassing both gate-to-gate and cradle-to-gate perspectives. A reduction of the CO2 emissions of around 66–87 % was obtained, depending on the fuel used to produce the steam needed in the PCCC unit and the analysis boundary considered. The primary energy consumption per avoided CO2 was estimated at 5.5–7.3 MJ/kgCO2. The specific cost per avoided CO2 also varies with the fuel choice and the analysis boundary. Through the optimal sizing of the PCCC unit, costs of 56–57 €/tCO2 were obtained for the integration of carbon capture in the plant. When a cradle-to-gate boundary is considered, costs for CO2 transportation and storage need to be accounted for, and costs of equivalent avoided CO2 ranging from 74.5 €/tCO2 to 124 €/tCO2 are estimated, depending on the transportation and storage scenario considered.

A study on decompression wave propagation characteristics during CO2 pipeline leakage with consideration of gas‐liquid transition

AbstractPipelines stand as the most cost‐effective method for large‐scale transportation of CO2 from a source point to the storage site, especially over extensive distances. The potential for crack propagation following a pipeline rupture highlights the need for precise analysis of decompression wave propagation. To accurately model this, understanding the decompression wave's propagation laws becomes imperative. Although previous studies have predominantly focused on pipeline leaks within the dense phase or supercritical state, the transition from liquid to gas during leakage significantly affects the decompression wave propagation. When a gaseous CO2 pipeline ruptures, the high Joule‐–Thomson coefficient causes a swift temperature plunge, potentially leading to a gas–liquid transition. However, research on how this phase transition impacts the decompression wave characteristics is limited. To address this gap, this study proposes a transition computational fluid dynamics model to predict the decompression wave behavior. The model is validated with an industrial‐scale full‐bore rupture experiment. The results reveal that the gaseous CO2 leakage induces a pressure plateau at a certain distance from the leakage due to the gas‐liquid phase transition. The influences of initial conditions on this pressure plateau and decompression wave are also explored. This study provides valuable insights into understanding the decompression wave behaviors of gaseous CO2 pipelines, which are essential for ensuring the safety and reliability of CO2 transportation within the carbon capture and storage technology chain. © 2024 Society of Chemical Industry and John Wiley &amp; Sons, Ltd.

Assessment of Potential and Techno-Economic Performance of Solid Sorbent Direct Air Capture with CO2 Storage in Europe.

Direct air capture with CO2 storage (DACCS) is among the carbon dioxide removal (CDR) options, with the largest gap between current deployment and needed upscaling. Here, we present a geospatial analysis of the techno-economic performance of large-scale DACCS deployment in Europe using two performance indicators: CDR costs and potential. Different low-temperature heat DACCS configurations are considered, i.e., coupled to the national power grid, using waste heat and powered by curtailed electricity. Our findings reveal that the CDR potential and costs of DACCS systems are mainly driven by (i) the availability of energy sources, (ii) the location-specific climate conditions, (iii) the price and GHG intensity of electricity, and (iv) the CO2 transport distance to the nearest CO2 storage location. The results further highlight the following key findings: (i) the limited availability of waste heat, with only Sweden potentially compensating nearly 10% of national emissions through CDR, and (ii) the need for considering transport and storage of CO2 in a comprehensive techno-economic assessment of DACCS. Finally, our geospatial analysis reveals substantial differences between regions due to location-specific conditions, i.e., useful information elements and consistent insights that will contribute to assessment and feasibility studies toward effective DACCS implementation.

Corrosion maps: Stability and composition diagrams for corrosion problems in CO2 transport

We present a Pourbaix-like graphical approach to assess the corrosive nature of impure CO2 streams for carbon capture and storage purposes. The effects of critical N- and S-containing impurities is evaluated. The model behind the approach assumes that chemical equilibrium is established, with some kinetic effects accommodated. The input is the composition of the stream (total quantity of S, N, H and O) and the output is the equilibrium composition (speciation). Comparison with experimental data shows that the content of acids in the CO2 stream upon reaching chemical equilibrium is a strong indicator of the corrosiveness of a given mixture.

Numerical simulation study of the effect of different factors on supercritical CO2 BLEVE

Abstract Global warming is harmful to the environment and CO2 is one of the major greenhouse gases. CCS-EOR technology can increase oil production and sequester CO2. During the storage and transportation of high-pressure CO2, BLEVE may occur. In this study, the dynamic pressure parameters in the supercritical CO2 BLEVE process were numerically simulated by using numerical simulation, and the effects of initial temperature and initial charge on the dynamic pressure parameters in the supercritical CO2 BLEVE process were mainly discussed. By thoroughly investigating the dynamic pressure of BLEVE of supercritical CO2, we can better understand and predict the conditions under which such accidents occur, and further improve the safety of industrial processes.

Carrier-driving CO2 separation by amine-rich membranes with intercalated graphene oxide

Amine-rich facilitated transport membranes (FTMs) attract great interest in intensifying the membrane-based CO2 separation processes. The high-molecular-weight polyvinylamine (PVAm) polymers containing fixed-site carriers of the amino groups were used to prepare highly CO2-permeable membranes. The sterically hindered PVAm polymers of poly(N-methyl-N-vinylamine) and poly(N-isopropyl-N-vinylamine) were obtained by functionalization of PVAm to provide superior CO2 solubility. By loading the mobile carriers of amino acid salt (AAS) and CO2-philic graphene oxide (GO), the prepared FTMs render enhanced CO2 permeance and CO2/N2 selectivity. The d-spacing of 8.8 Å and the ultramicropores of 3.5 Å from GO nanosheets provide the combination of both selective surface flow and molecular sieving mechanisms to achieve improved CO2 permeance and CO2/N2 selectivity. In addition, the intercalation of GO hinders N2 transport through the membrane due to a longer pathway, while the mobile carriers of AAS introduced into the PVAm matrix facilitate CO2 transport through the selective layer. Therefore, the CO2/N2 selectivity of the prepared FTMs was significantly enhanced to 171 based on the intensified carrier-driving transport mechanism. It can be concluded that amine-rich membranes based on both fixed and mobile carriers of the amino groups together with intercalated GO can synergistically improve the CO2/N2 separation performance, and be potentially applied for CO2 capture from flue gas.

In-situ enforcing molecular diffusion to functionalize hollow fiber carbon membranes enables efficient CO2 separations

Microporous carbon membranes with tunable micropores are attractive materials for CO2 separations. Tailoring the gas transport channels is an effective strategy to achieve high separation performance, while it remains challenging due to the lack of control over sub-nanopores. Herein, we present an in-situ molecular functionalization strategy wherein the confined sub-nanopore properties are designed by enforcing molecules to diffuse over pores and functionalize the pore affinity. By enforcing oxygen-functionalization, a strong CO2 affinity between the carbon matrix and CO2 molecules is generated, which facilitated CO2 transport, thereby enhancing the CO2 permeability by ∼4.7-fold and without sacrificing molecular sieving ability for gas mixtures, like CO2/N2 and CO2/CH4. The functionalization mechanism was confirmed using reactive force field molecular dynamics (ReaxFF-MD) simulations. Furthermore, this strategy, which was directly applied to hollow fiber membrane modules, provides a facile and scalable approach, and expands the currently limited library of penetrative micropore tailoring of microporous membranes.

Analysis of the gas transport resistance of CO2 and CH4 through ultra-thin DD3R zeolite membrane

Ultra-thin DD3R zeolite membranes exhibit excellent separation properties for CO2 capture from natural gas, as well as the lower transmembrane resistance. However, the interfacial transport of permeation gas in such systems may dominate the whole separation process. In this work, we employed external force non-equilibrium molecular dynamic (EF-NEMD) simulation to predict the single-component permeabilities of CO2 and CH4 through a defect-free DD3R zeolite membrane at different pressured drops. By explicitly including the gas transport from bulk phase to zeolitic channels, the predicted results of EF-NEMD simulation showed good agreements with the reported experimental data. The contribution of interfacial resistance over the total transport resistance (Rinter/Rtotal) was further evaluated for the membranes with different thicknesses under temperatures between 273 K and 373 K. The results revealed a decrease in Rinter/Rtotal with increasing membrane thickness, leading to a reduction in CO2/CH4 selectivity, and the critical thickness (Rinter/Rtotal < 0.01) was determined to be approximately 300 nm at pressure of 1.0 MPa and temperature of 298 K. Similarly, the Rinter/Rtotal decreased with increasing temperature due to the augmentation in molecule kinetic energy. Furthermore, it was confirmed that the gas adsorption effect could expand the effective size of eight membered ring (8-MR) channels in DD3R zeolite membrane, thereby decreasing the CO2/CH4 selectivity, despite higher permeation fluxes. The above discoveries essentially benefit the design of the ultra-thin DD3R zeolite membrane through an understanding of CO2 and CH4 transport behaviors.

Enhancing CO2 transport with plasma-functionalized ionic liquid membranes

The ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate treated with radiofrequency plasma is proposed for functionalization and immobilization on polyethersulfone supports to form supported ionic liquid membranes for CO2 separation. The effects of treatment time and transmembrane pressure difference on CO2 permeance were evaluated. The best gas permeation performance was obtained with a treatment time of 10 min and the transmembrane pressure difference was 0.25 MPa. Characterization of the materials by Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy and nuclear magnetic resonance spectroscopy demonstrates that the IL is grafted with carboxyl groups and deprotonated through plasma treatment. A preliminary mechanism for the plasma treatment and facilitated transport of CO2 has been proposed on this basis.

Wind as a Driver of Peat CO2 Dynamics in a Northern Bog.

The online version contains supplementary material available at 10.1007/s10021-024-00904-1.

Partitioning seasonal stem carbon dioxide efflux into stem respiration, bark photosynthesis, and transport-related flux in Scots pine.

Stem CO2 efflux is an important component of the carbon balance in forests. The efflux is considered to principally reflect the net result of two dominating and opposing processes: stem respiration and stem photosynthesis. In addition, transport of CO2 in xylem sap is thought to play an appreciable role in affecting the net flux. This work presents an approach to partition stem CO2 efflux among these processes using sap-flux data and CO2-exchange measurements from dark and transparent chambers placed on mature Scots pine (Pinus sylvestris) trees. Seasonal changes and monthly parameters describing the studied processes were determined. Respiration contributed most to stem net CO2 flux, reaching up to 79% (considering the sum of the absolute values of stem respiration, stem photosynthesis, and flux from CO2 transported in xylem sap to be 100%) in June, when stem growth was greatest. The contribution of photosynthesis accounted for up to 13% of the stem net CO2 flux, increasing over the monitoring period. CO2 transported axially with sap flow decreased towards the end of the growing season. At a reference temperature, respiration decreased starting around midsummer, while its temperature sensitivity increased during the summer. A decline was observed for photosynthetic quantum yield around midsummer together with a decrease in light-saturation point. The proposed approach facilitates modeling net stem CO2 flux at a range of time scales.

#1001 Model-based profiling of bicarbonate supplementation during a hemodialysis cycle

Abstract Background and Aims Bicarbonate is delivered to hemodialysis (HD) patients via diffusion following a concentration gradient across the dialyzer membrane. However, the concentration of bicarbonate in the dialysis fluid ([HCO3]d) is usually not individualized for the specific patient's conditions, as no clear guidelines are provided, which leads to suboptimal pre- and post-dialytic plasma bicarbonate concentrations ([HCO3]p) during each treatment cycle. We used a mathematical model to predict the outcomes of a week-long HD cycle with time-dependent [HCO3]d in 24 patients, tuning the [HCO3]d prescription to keep the simulated pre-dialytic [HCO3]p in the range 22-24 mEq/L throughout the week. The [HCO3]d profiles thus developed were then tested, and [HCO3]p during HD compared with those using a constant [HCO3]d in the same patients. Method The compartmental model (Pietribiasi et al PLOS ONE 2023) describes the transport of total CO2, O2, and total buffer base in arterial and mixed-venous blood (plasma and red blood cells), tissues (interstitial and intracellular fluid), and lung capillaries and alveoli, calculating derivate quantities such as bicarbonate concentration, pH, partial pressure of CO2. The patients underwent one week of standard HD with constant [HCO3}d (Week 1, [HCO3]d = 33.6 ± 1.8 mEq/L) consisting of 3 sessions (HD1, HD2, HD3) to estimate the baseline model parameters and, successively, an intervention week (Week 2), during which the model-derived [HCO3]d profiles were implemented. Each profile consisted of a single step increase after 2 hours of HD, the two values of [HCO3]d chosen for each session and patient according to the model's simulations. Blood samples for the blood gas analyzer were taken before and after each session, and each hour during HD2. Results [HCO3]p profiles in Week 2 showed a more linear increase compared those of Week 1 (Fig. 1). The efficacy of the response to the model-based treatment was different depending on whether the intervention aimed to decrease or increase pre-dialytic [HCO3]p during Week 2 (Fig. 2). In the group of patients attempting to decrease pre-dialytic [HCO3]p (Decrease group, n = 10, average [HCO3]d = 31.3 ± 1.5 mEq/L), a significant fraction of sessions achieved the target (60% across the whole week). In contrast, among the patients attempting to increase pre-dialytic [HCO3]p (Increase group, n = 6, average [HCO3]d = 35.3 ± 2.0 mEq/L), the model-based prescription was effective only in increasing post-dialytic concentration (20% of sessions achieved pre-dialytic targets). By comparison, during Week 1 only 30% and 10% of sessions were in the target range for Decrease and Increase groups, respectively. Patients for which we didn't want to alter pre-dialytic [HCO3]p were termed the Neutral group (n = 8, average [HCO3]d = 33.3 ± 2.1 mEq/L, 40% and 50% of sessions in the target [HCO3]p range in Week 1 and 2, respectively). Conclusion The model-based profiling intervention was only partially successful in achieving the targets for pre-dialytic [HCO3]p in Week 2. The reasons why pre-dialytic [HCO3]p were resistant to the model-based [HCO3]d in the Increase group are not clear, but it could be that the increase in the average [HCO3]d was too small (6-7% higher than Week 1). However, in the Decrease group a similar difference was sufficient to produce a more marked decrease in pre-dialytic [HCO3]p. The profiling of [HCO3]d was shown to be effective in reducing the time the patients spend at higher [HCO3]p. Nevertheless, our study demonstrated that, upon refinement, mathematical modeling can be used to develop individualized treatments to pilot the markers of the acid-base response to HD towards desired values.

Three-dimensional detection of CO2 and wind using a 1.57 µm coherent differential absorption lidar

A 1.57-µm coherent differential absorption lidar is demonstrated for measuring three-dimensional CO2 and wind fields simultaneously. The maximum detection range of CO2 is up to 6 km with a range resolution of 120 m and a time resolution of 1 min. A preliminary assessment of instrument performance is made with a 1-week continuous observation. The CO2 concentration over a column from 1920 to 2040 m is compared with the one measured by an optical cavity ring-down spectrometer placed on a 2 km-away meteorological tower. The concentration is strongly correlated with the in-situ spectrometer with a correlation coefficient and RMSE of 0.91 and 5.24 ppm. The measurement accuracy of CO2 is specified with a mean and standard deviation of 2.05 ppm and 7.18 ppm, respectively. The regional CO2 concentration and the three-dimensional wind fields are obtained through different scanning modes. Further analysis is conducted on vertical mixing and horizontal transport of CO2 by combining with the measured wind fields.