Water CO2 Research Articles

Integrated study on CO2 enhanced oil recovery and geological storage in tight oil reservoirs

Carbon utilization, and sequestration (CUS) in tight oil reservoirs stands as a pivotal strategy for enhancing oil recovery and mitigating CO2 emissions. Research on CUS mainly focuses on the calculation of overall displacement efficiency and the total sequestration amount. However, the primary control and sequestration mechanisms throughout the life cycle of CUS, as well as the contribution of each mechanism at different development stages and under various injection and production parameters, are not clear, which limits effective guidance for oilfield development. Therefore, this paper studies the entire life cycle of tight oil reservoirs, from water flooding to CO2 flooding and CO2 sequestration after reservoir abandonment. The contribution degree changes of dissolution, structural, residual gas and mineralized sequestration mechanisms during the whole life cycle are analyzed. The results show that the main sequestration mechanism during CO2 flooding stage and injection sequestration stage after shutting down production wells is structural sequestration, which accounts for 84.75%. In the 2000 years following the cessation of CO2 injection, the proportion of structural sequestration gradually decreases, with a cumulative decrease of 12.41%, and it is mainly converted to the other three sequestration modes, with the largest increase in mineralization sequestration, reaching 8.81%, mainly due to the reaction of dicalcium silicate with CO2 to produce more stable calcite. When the injection pressure was increased from 23 MPa to 44 MPa, the sequestration efficiency increased by 18.45%. An interesting finding is that the solubility of CO2 in water in the target reservoir reaches its lowest point at 80 °C, and both warming and cooling at this point are conducive to the dissolution and sequestration of CO2. The initial pH value of formation water mainly affects mineralization and sequestration. The rate of calcite production and the contribution of CO2 dissolution and sequestration are positively correlated with water saturation. The findings underscore the importance of understanding dynamic contributions of various sequestration mechanisms and optimizing conditions to enhance CO2 sequestration efficiency.

Role of foliar iron in modulating primary and antioxidant mechanisms of Mentha piperita L. under different light conditions

The present study aims to uncover the role of foliar iron in modulating primary and antioxidant mechanisms of Mentha piperita L. under light conditions. Plants were distributed in a completely randomized design and submitted to five Fe concentrations; 0 (control), 0.5, 1.0, 1.5 and 2.0 g L−1. And under two irradiance conditions; I100% (full sun) and I50% (50% irradiance). Forty-eight hours after foliar Fe application, the following parameters were determined: gas exchange, chlorophyll (a and b), carotenoids and anthocyanin content, chlorophyll a fluorescence, peroxidase and superoxide dismutase activities. The highest Fe concentrations affect the internal CO2 concentration (Ci) and water use efficiency, according to the photochemical extinction coefficient and peroxidase and superoxide dismutase activities. I100% increased the minimum dark-adapted leaf fluorescence and electron transport rate, while, I50% increased the chlorophyll values, and carotenoid content, Ci and transpiration, maximum dark-adapted leaf fluorescence, antenna quantum efficiency and dark-adapted fluorescence. We discovered that isolated treatments are more effective in modifying the response mechanisms of M. piperita plants and the interaction of Fe and irradiance tends to alter antioxidant metabolism.

Scanning Gas Diffusion Electrode Setup for Real-Time Analysis of Catalyst Layers.

The scanning gas diffusion electrode (S-GDE) half-cell is introduced as a new tool to improve the evaluation of electrodes used in electrochemical energy conversion technologies. It allows both fast screening and fundamental studies of real catalyst layers by applying coupled mass spectrometry techniques such as inductively coupled plasma mass spectrometry and online gas mass spectrometry. Hence, the proposed setup overcomes the limitations of aqueous model systems and full cell-level studies, bridging the gap between the two approaches. In this proof-of-concept work, standard fuel cell electrodes are investigated at elevated oxygen reduction reaction current densities, while dissolved Pt x+ ions in the electrolyte and gaseous CO2 in the outlet gas stream are detected to track platinum dissolution and carbon corrosion, respectively. Relevant current densities of up to 0.75 A cm-2 are demonstrated. The electrochemically active surface area, oxygen reduction reaction activity, and Pt dissolution rates are quantified and benchmarked to the values obtained in the conventional stationary GDE half-cell. Moreover, it is found that Pt dissolution is suppressed when O2 is purged into the catalyst layer. Overall, this work demonstrates the feasibility of fast fuel cell electrode screening obtaining, complementary to electrochemical, mass spectrometry data necessary in fundamental studies on structure/performance relationships under actual reaction conditions. While Pt/C, in relevance to its fuel cell application, is used in this study, the proposed setup can be applied in water electrolysis, CO2 conversion, metal-air batteries, and other neighbor technologies.

Fluxes, Mechanisms, Influencing Factors, and Bibliometric Analysis of Tree Stem Methane Emissions: A Review

Methane (CH4) emissions exert large effects on the global climate. Tree stems are vital sources of emissions in ecosystem CH4 budgets. This paper reviewed the number of publications, journals, authors, keywords, research hotspots, and challenges. A total of 990 articles from 2006 to 2022 were collected based on the Web of Science database. The intellectual base was analyzed using CiteSpace 6.3.1 and VOSviewer 1.6.20 softwares. The results illustrated a growing trend in the study of tree stem methane emissions. The United States was the most research-active country; however, the most active institution was the Chinese Academy of Sciences in China. The research on stem methane emission by Vincent Gauci, Katerina Machacova, Zhi-Ping Wang, Kazuhiko Terazawa, Kristofer R. Covey, and Sunitha R. Pangala has had a significant impact. Current research indicates that stem CH4 emissions significantly vary among different tree species and are influenced by leaf type, forest type, tree height, whether the trees are alive or dead, and other environmental conditions (such as soil water content, air temperature, CO2 fluxes, and specific density). Soil CH4 fluxes and production by methanogens in heartwood were the primary sources of tree stem methane. Some pectin or cellulose from trees may also be converted into methane. Moreover, methane can be produced and released during the decomposition of deadwood by basidiomycetes. Furthermore, there are some trends and challenges for the future: (1) distinguishing and quantifying emissions from various sources; (2) accurately assessing the impact of floods on methane emissions is crucial, as the water level is the main factor affecting CH4 emissions; and (3) addressing the limited understanding of the microbial mechanisms of methane production in different tree species and investigating how microbial communities affect the production and emission of methane is vital. These advances will contribute to the accurate assessment of methane emissions from global ecosystems.

A non‐ionic green surfactant extracted from the Anabasis setifera plant for improving bulk properties of CO2‐foam in the process of enhanced oil recovery from carbonate reservoirs

AbstractFoam, as a gas‐in‐liquid colloid, has a higher appearance viscosity than the one of both gas and liquid that form it. Adjusting the mobility ratio of the injected fluid–oil system and increasing gas diffusion in the foam injection process increase oil production. With these properties, foam as an injection fluid in fractured reservoirs has a major effect on oil production from the matrixes and prevents premature production of injection fluid. Surfactants are common foaming agents in injection water. Saponins are known as plant‐derived surfactants for forming stable foam. This feature, along with its cheap price and availability, can make them candidates for enhanced oil recovery (EOR) by the foam injection method. However, the utilization of CO2 as the gaseous phase in foam introduces additional machanisms of CO2 injection to the oil recovery operations. In this assessment, a non‐ionic green surfactant derived from the Anabasis setifera plant was used as a foaming agent, while CO2 served as the gas phase. A series of surface tension tests in CO2 environment were performed to determine the optimal concentration of the surfactant. Foaming tests were performed by a designed foam generator. The produced CO2‐foam was then injected into a fractured carbonate plug with six matrixes (with one horizontal and two vertical fractures). Based on the results, the water–CO2 surface tension was reduced to 20.549 mN/m. The optimum salinity based on the foam stability was 10,000 ppm. The half‐life of the foam was determined to be 40 min. Also, the foam characterization showed that the foamability of the surfactant was favourable for increasing oil production so that by secondary flooding, an oil recovery of more than 66% was achieved from the fractured carbonate plug.

Microwave-assisted pyrolysis of biomass waste for production of high-quality biochar: Corn stover and hemp stem case studies

The efficient conversion of biomass waste into valuable products is a critical challenge in sustainable energy and environmental management. Microwave pyrolysis of hemp stem and corn stover was studied for producing biochar suitable for CO2 adsorption, catalysts, water treatment, and soil enhancement. The effects of microwave power and absorbent agents on maximum temperature, yields, and biochar properties were investigated. Elevated power (33–120 W/g) reduced yield (42–16 wt%, 38 to 16 wt%) but increased carbon content (67–78 wt%, 65 to 75 wt%), BET surface area (1.05–69.37 m2/g, 0.59–43.18 m2/g) for hemp stem and corn stover respectively. Microwave absorbents like graphite, activated carbon, and water improved heating and biochar quality. Activated carbon notably increased carbon content (76–82 % wt, 71–80 % wt) and surface area (6.59–91.99 m2/g, 9.99–50.51 m2/g) for hemp stem and corn stover respectively. CO2 adsorption highlighted biochar microstructure with pore sizes averaging around 1 nm for both biomass. These findings demonstrate the potential of microwave-assisted pyrolysis and the use of absorbent agents to produce high-quality biochar for various applications.

Synergy of Photogenerated Electrons and Holes toward Efficient Photocatalytic Urea Synthesis from CO2 and N2

AbstractDirectly coupling N2 and CO2 to synthesize urea by photocatalysis paves a sustainable route for urea synthesis, but its performance is limited by the competition of photogenerated electrons between N2 and CO2, as well as the underutilized photogenerated holes. Herein, we report an efficient urea synthesis process involving photogenerated electrons and holes in respectively converting CO2 and N2 over a redox heterojunction consisting of WO3 and Ni single‐atom‐decorated CdS (Ni1‐CdS/WO3). For the photocatalytic urea synthesis from N2 and CO2 in pure water, Ni1‐CdS/WO3 attained a urea yield rate of 78 μM h−1 and an apparent quantum yield of 0.15 % at 385 nm, which ranked among the best photocatalytic urea synthesis performance reported. Mechanistic studies reveal that the N2 was converted into NO species by ⋅OH radicals generated from photogenerated holes over the WO3 component, meanwhile, the CO2 was transformed into *CO species over the Ni site by photogenerated electrons. The generated NO and *CO species were further coupled to form *OCNO intermediate, then gradually transformed into urea. This work emphasizes the importance of reasonably utilizing photogenerated holes in photocatalytic reduction reactions.

Synergy of Photogenerated Electrons and Holes toward Efficient Photocatalytic Urea Synthesis from CO2 and N2.

Directly coupling N2 and CO2 to synthesize urea by photocatalysis paves a sustainable route for urea synthesis, but its performance is limited by the competition of photogenerated electrons between N2 and CO2, as well as the underutilized photogenerated holes. Herein, we report an efficient urea synthesis process involving photogenerated electrons and holes in respectively converting CO2 and N2 over a redox heterojunction consisting of WO3 and Ni single-atom-decorated CdS (Ni1-CdS/WO3). For the photocatalytic urea synthesis from N2 and CO2 in pure water, Ni1-CdS/WO3 attained a urea yield rate of 78 μM h-1 and an apparent quantum yield of 0.15 % at 385 nm, which ranked among the best photocatalytic urea synthesis performance reported. Mechanistic studies reveal that the N2 was converted into NO species by ⋅OH radicals generated from photogenerated holes over the WO3 component, meanwhile, the CO2 was transformed into *CO species over the Ni site by photogenerated electrons. The generated NO and *CO species were further coupled to form *OCNO intermediate, then gradually transformed into urea. This work emphasizes the importance of reasonably utilizing photogenerated holes in photocatalytic reduction reactions.

A critical meta-analysis of CO2-water-rock interaction in basalt for CO2 storage: A review based on global and Indian perspective

Global warming and energy security lead to the hunt for alternative energy sources and CO2 emission mitigation technologies like carbon capture and storage (CCS). CCS is a prominent technique and its success depends on the sites of storage and agents influencing the storage efficiency. Geological formations are much safer as compared to oceanic injection for CO2 storage and include formations like sedimentary and igneous formations. Igneous formations like peridotite, komatiites, and basalt have huge potential to store CO2 and take the least time to convert the injected gas into solid carbonates along with the advantage of negligible leakage (as injected gas converts to carbonates through carbon mineralization). Carbon mineralization is a complex process involving the interaction of water–CO2–rock to form solid carbonates. In this review, we have highlighted the carbon mineralization in basalt by discussing the dissolution and precipitation mechanism. The discussion includes the uncertainty in the role of aluminum ions and siderite precipitation during CO2 storage in basalt. The review article also presents the first insight for the qualitative assessment of the CO2 storage potential of Deccan volcanic provinces (DVP) in India concerning the rock composition, injection depth, and type of injection. The mineralogy, and structure of the Basaltic province of DVP support CO2 storage. The principal minerals including calcic plagioclase and pyroxene, support mineral carbonation. Out of the total available area of DVP, 95% consists of tholeiitic basalt, exhibiting a simple flow structure. Additionally, the area is seismically safe for CO2 storage. The challenges and future research gap areas highlighted in this review article include suitable depth for injection, lateral continuity, the role of geothermal gradient, water availability, and public acceptance. Thus, the article provides a critical insights into the exploration and development of CCS technologies in India, emphasizing the importance of the Deccan Volcanic Provinces in achieving net-zero goals.

Two decades of riparian woodland water vapor and carbon dioxide flux responses to environmental variability

Riparian woodlands occupy a small area of global drylands but are hotspots for carbon and water cycling because groundwater supplements a small moisture supply from precipitation (P). Despite their regional importance, it is unclear if and how climate variability alters water vapor and carbon dioxide (CO2) fluxes in these ecosystems, and how ecosystem drivers vary across annual and seasonal scales. Here we use 21 years of eddy covariance measurements to understand land-atmosphere controls on water vapor and CO2 fluxes of a semiarid riparian mesquite (Prosopis velutina) woodland with year-round access to deep groundwater and highly variable summer and winter rainfall. Access to groundwater supplemented evapotranspiration (ET) that exceeded precipitation (ET:P range 1.9–5.4), making this riparian forest a substantial CO2 sink (367 ± 83 g C m-2yr-1). Contrary to general expectations of regional climatic drying, there was a shift to more favorable water conditions as P and soil moisture increased over time. Annual gross ecosystem production (GEP) and respiration (Reco) increased at the same rate (∼9 g C m-2yr-2) due to GEP and Reco increases during the wettest periods of the year. Growth year separation based on GEP phenology and regression models show that water availability and antecedent phenophase fluxes control seasonal ET and GEP, with CO2 fertilization detected only during winter dormancy, the least-active phenophase. The major Reco driver during the spring and summer was GEP, and this coupling intensified following the onset of summer rainfall. Groundwater subsidies support ET during the dry growing season and decouple water vapor and CO2 fluxes. These results highlight the dynamic nature of water vapor and CO2 cycling in semiarid riparian woodlands, the value of groundwater subsidies to buffering ecosystem responses from the interannual effects of climate variability, and the importance of two water sources in driving seasonal ecosystem responses.

Photothermal CO2 conversion to ethanol through photothermal heterojunction-nanosheet arrays

Photothermal CO2 conversion to ethanol offers a sustainable solution for achieving net-zero carbon management. However, serious carrier recombination and high C-C coupling energy barrier cause poor performance in ethanol generation. Here, we report a Cu/Cu2Se-Cu2O heterojunction-nanosheet array, showcasing a good ethanol yield under visible–near-infrared light without external heating. The Z-scheme Cu2Se-Cu2O heterostructure provides spatially separated sites for CO2 reduction and water oxidation with boosted carrier transport efficiency. The microreactors induced by Cu2Se nanosheets improve the local concentration of intermediates (CH3* and CO*), thereby promoting C-C coupling process. Photothermal effect of Cu2Se nanosheets elevates system’s temperature to around 200 °C. Through synergizing electron and heat flows, we achieve an ethanol generation rate of 149.45 µmol g−1 h−1, with an electron selectivity of 48.75% and an apparent quantum yield of 0.286%. Our work can serve as inspiration for developing photothermal catalysts for CO2 conversion into multi-carbon chemicals using solar energy.

Understanding Photovoltage Enhancement in Metal-Insulator Semiconductor Photoelectrodes with Metal Nanoparticles.

A metal-insulator-semiconductor (MIS) structure holds great potential to promote photoelectrochemical (PEC) reactions, such as water splitting and CO2 reduction, for the storage of solar energy in chemical bonds. The semiconductor absorbs photons, creating electron-hole pairs; the insulator facilitates charge separation; and the metal collects the desired charge and facilitates its use in the electrochemical reaction. Despite these attractive features, MIS photoelectrodes are significantly limited by their photovoltage, a combination of the voltage generated from photon absorption minus the potential drop across the insulator. Herein, we use multiscale continuum modeling of the carrier, electrolyte, and interfacial transport to identify strategies for mitigating the deleterious potential drop across the insulator and enabling high MIS photovoltages. To this end, we model Ni/SiO2/n-Si photoanodes that employ a planar Ni film or Ni nanoparticles (np-MIS) and validate both models using experimental polarization curves and photovoltage measurements from the literature. The simulations reveal that the insulator potential drop is lower and hence achieves higher photovoltages for np-MIS structures than MIS structures because the electrolyte screens charge trapped at defect states between the semiconductor and the insulator. This electrolyte charge screening phenomenon can be further leveraged by using low loadings or small nanoparticles, which not only minimize the interfacial potential drop but also improve the photocurrent by enabling more light absorption. These insights contribute to the optimization of the np-MIS structures for sustainable energy conversion.

Enhancing Photocathodic Performances of Particulate-CuGaS2-Based Photoelectrodes via Conjugation with Conductive Organic Polymers for Efficient Solar-Driven Hydrogen Production and CO2 Reduction.

Modification with conductive organic polymers consisting of a thiophane- or pyrrole-based backbone improved the cathodic photocurrent of a particulate-CuGaS2-based photoelectrode under simulated solar light. Among these polymers, poly(3,4-ethylenedioxythiophene) (PEDOT) was the most effective in the improvements, providing a photocurrent 670 times as high as that of the bare photocathode. An incident-photon-to-current efficiency (IPCE) for water reduction to form H2 under monochromatic light irradiation (450 nm at 0 V vs RHE) was ca. 11%. The most important point is that modification of the conductive organic polymers does not involve any vacuum processes. This importance lies in the use of an electrochemically oxidative polymerization, not in a physical process such as vapor deposition of metal conductors. This is expected to be advantageous in the large-scale application of photocathodes consisting of particulate photocatalyst materials toward industrial solar-hydrogen production using photoelectrochemical-cell-based devices. Artificial photosynthesis of water splitting and CO2 reduction under simulated solar light was demonstrated by combining the PEDOT-modified CuGaS2 photocathode with a CoOx-loaded BiVO4 photoanode. Furthermore, how the cathodic photocurrent of the particulate-CuGaS2-based photocathode was drastically improved by the modification was clarified based on various characterizations and control experiments as follows: (1) selectively filling cavities between the particulate CuGaS2 photocatalysts and a conductive substrate (FTO; fluorine-doped tin oxide) with the polymers and (2) using a large driving force for carrier transportation governed by the polymers' redox potentials adjusted by functional groups.

Modeling phase equilibria for a water-CO2-hydrocarbon mixture using CPA equation of state in CO2 injection EOR-storage processes: a Colombian case study

Currently, it is necessary to reduce CO2 emissions into the atmosphere. The oil industry in Colombia can contribute through CO2 injection processes in depleted fields. To achieve this, it is essential to have knowledge of the physicochemical interactions of CO2 with reservoir fluids. To integrate CO2, water and hydrocarbon phases, advanced models are required that capture the phenomenology of thermodynamic equilibrium. The CPA (Cubic-Plus-Association) equation of state is an equation that adds an associative term to model the interaction of water with the hydrocarbon and CO2 phase. In this work, the CO2 injection process is thermodynamically modeled in a depleted Colombian reservoir case study. There is a compositional fluid with a gradient of PVT properties in a vertical relief of 10,000 ft at a depletion condition of 2,000 psi @ 15,374 ft and an oil-water contact (OWC) at 17,000 ft. CO2 injections between 10 and 80 mol% were carried out, and through the CPA equation of state, the swelling conditions of the crude oil, the solubility of CO2 in the formation water and the pressurization of the system were evaluated. The associative parameters of the equation were taken from literature and estimated through molecular dynamics simulations of water-CO2-Hydrocarbon interactions. This thermodynamic modeling with an advanced equation of state and use of molecular dynamics simulations allowed us to simulate different CO2 injection scenarios in a compositional fluid. The development of these types of studies is key to carrying out successful CO2 injection processes focused on enhanced recovery (EOR) and CO2 storage in the porous medium in a Colombian-depleted compositional reservoir.

A Multiphase and Multicomponent Model and Numerical Simulation Technology for CO2 Flooding and Storage

In recent years, CO2 flooding has become an important technical measure for oil and gas field enterprises to further improve oil and gas recovery and achieve the goal of “dual carbon”. It is also one of the concrete application forms of CCUS. Numerical simulation based on CO2-EOR plays an indispensable role in the study of the mechanism of CO2 flooding and buried percolation, allowing for technical indicators to be selected and EOR/EGR prediction to be improved for reservoir engineers. This paper discusses the numerical simulation techniques related to CO2 flooding and storage, including mathematical models and solving algorithms. A multiphase and multicomponent mathematical model is developed to describe the flow mechanism of hydrocarbon components–CO2–water underground and to simulate the phase diagram of the components. The two-phase P-T flash calculation with SSI (+DEM) and the Newton method is adopted to obtain the gas–liquid phase equilibrium parameters. The extreme value judgment of the TPD function is used to form the phase stability test and miscibility identification model. A tailor-made multistage preconditioner is built to solve the linear equation of the strong-coupled, multiphase, multicomponent reservoir simulation, which includes the variables of pressure, saturation, and composition. The multistage preconditioner improves the computational efficiency significantly. A numerical simulation of CO2 injection in a carbonate reservoir in the Middle East shows that it is effective for researching the recovery factor and storage quantity of CO2 flooding based on the above numerical simulation techniques.

Healable multilayered photocatalysts promote durability and productivity of solar-driven CO2 conversion

Numerous studies have focused on efficient CO2 photoreduction on short notice. However, more hours of efficient and selective CO2 and pure water photoconversion without precious metals or sacrificing reagents should be emphasized. Herein, a multilayer (SrTiO3/Ce:CaF2/CuNi/Ce:CaF2/TiN) is utilized with a high selectivity of 87 % for healable photocatalytic CO2 and pure water conversion without sacrificial reagents and the longest service life for the Cu nanolayers, to the best of our knowledge. Meanwhile, the photocatalytic activity, optical absorption, and charge separation ability of SrTiO3/Ce:CaF2/CuNi/Ce:CaF2/TiN can be recovered after regeneration. The deactivation and healable mechanism are illuminated that the adsorption of CO2 molecules at the photocatalyst surface is changed from M-CO2 to MO-CO2, due to the oxidation of active sites, resulting in the deactivation of CO2 reduction. The Ce:CaF2 nanolayers can accommodate oxygen atoms effectively to heal the photocatalyst. The article proposes a feasible way for commercial CO2 and pure water photoconversion.

Changes of oxygen consumption rates in response to various environmental factors and different anesthetic methods in juvenile hybrid sturgeon, Acipenser baeri♀×Acipenser schrencki♂

Live fish transportation plays a crucial role in realizing the value of aquaculture in sturgeons. However, hypoxia and hypercapnia are the major issues during the high-density transportation of live fish. Therefore, monitoring the changing environmental factors (such as water temperature, salinity, and pH) or anesthesia methods (MS-222, dissolved CO2, or low-voltage direct electrical current), which can potentially alter the oxygen consumption of fish, are crucial for a better understanding of the necessary conditions for live fish transportation. A semi-open respirometry system was used to quantify the oxygen consumption and respiration frequency of hybrid sturgeon (Acipenser baeri♀×Acipenser schrencki♂). The results indicate that the oxygen consumption rate and respiration frequency of hybrid sturgeon increased linearly with water temperature from 1.4 °C to 25°C. The oxygen consumption rate of hybrid sturgeon increased with the increase of salinity in the range from 3 to 10 ‰ in 9 hours (P < 0.05). Respiration frequency decreased but did not affect the oxygen consumption rate when pH was from 8.1 to 9.8. Exposure to low-voltage direct electrical current ranging from 0.4 to 1.0 V/cm significantly increased the respiration frequency (P < 0.05). The oxygen consumption rate maintained below 1 mg/(g·h) when CO2 concentration ranges from 8.5 to 67.85 mg/L. Compared with the change of oxygen consumption rate and respiration frequency with MS-222 at the range from 5 to 30 mg/L, immersion of fish into more than 8.5–67.85 mg/L dissolved CO2 in water could as an alternative anesthetic method for hybrid sturgeon. These findings in the study may contribute to the culture, live fish transportation, and basic research in hybrid sturgeon.

Cu infiltrated Ni-YSZ cathode in CO2 (+H2) stream: Reverse water gas shift vs. CO2 electrolysis

Ni-Yttria Stabilized Zirconia (Ni-YSZ) cermet electrode is known to perform in CO2 (+H2) stream. Introducing H2 in CO2 containing streams enables thermochemical reverse water gas shift reaction (rWGS: CO2 + H2 → CO + H2O) at open circuit. Without the application of any bias, the rWGS responds positively to an increase in temperature and concentrations of CO2 and H2. Application of bias results in enhancement in CO yield above the rWGS baseline value. With bias, both CO2 and H2O electrolysis are enabled. The infiltration of Cu on the Ni-YSZ backbone results in significant improvement of the reaction kinetics and increases H2 and CO production. Impedance analysis indicates that the kinetic limitation originates from reaction steps with slower time constants with Ni{Cu}x-YSZ outperforming Ni-YSZ in this aspect. Cu infiltration suppresses particle coarsening typically observed in Ni-YSZ.

Large-scale purification of a deprotected macrocyclic peptide by supercritical fluid chromatography (SFC) integrated with liquid chromatography in discovery chemistry

A macrocyclic peptide A was successfully purified in large quantities (∼30 g) in >95 % purity by an integrated two-step orthogonal purification process combining supercritical fluid chromatography (SFC) with medium-pressure reverse-phase liquid chromatography (MP-RPLC). MP-RPLC was used to fractionate the crude peptide A, remove unwanted trifluoroacetic acid (TFA) originating from the peptide A cleavage off the resin, and convert the peptide A into ammonium acetate salt form, prior to the final purification by SFC. A co-solvent of methanol/acetonitrile containing ammonium acetate and water in CO2 was developed on a Waters BEH 2-Ethylpyridine column. The developed SFC method was readily scaled up onto a 5 cm diameter column to process multi-gram quantities of the MP-RPLC fraction to reach > 95 % purity with a throughput/productivity of 0.96 g/h. The incorporation of SFC with MP-RPLC has been demonstrated to have a broader application in other large-scale polypeptide purifications.

Geothermometrical calculations of thermal waters affected by secondary processes: The case of Sierra Elvira (Spain)

Geothermometrical calculations in thermal systems are often limited by the presence of secondary processes that modify the chemistry of the deep reservoir fluid during the ascent to the surface (e.g., mixing, degasification). The effect of secondary processes can be avoided by applying some techniques to reconstruct the chemical equilibrium at depth and the fluid original composition. However, the reconstruction of thermal waters mixed with cold surficial waters is complicated when the dilution factors are unknown. For that case, here, we propose to use an approach consisting of the simulation of a concentration process that removed different amounts of water from the thermal solutions until the equilibrium temperatures of anhydrite and quartz converge for the waters affected by mixing in unknown proportions. Using classical geothermometers and geothermometrical modeling, including the water removal process and CO2 degasification, a temperature range of 78 ± 9 °C at depth has been established for the Sierra Elvira geothermal system whose waters are in chemical equilibrium with respect to calcite, dolomite, anhydrite, quartz, illite, pyrophyllite and beidellite-K. The good agreement in the temperatures obtained for the different thermal fluids of the system suggests a common reservoir for all of them. The methodology used in this study can be applied to other geothermal systems in carbonate rocks affected by mixing.