High-pressure Carbon Dioxide Research Articles

Thermal optimization of ivermectin in supercritical carbon dioxide and ethanol to produce nano medicine

The solubility of ivermectin in high pressure carbon dioxide (CO2) at 338, 328, 318, and 308 K temperatures was investigated with and without an ethanol. Several methods were employed to model the data obtained from the experiments. ivermectin exhibited solubility values ranging from 0.130 × 10−5 to 1.760 × 10−4 in the binary system and 1.880 × 10−5 to 1.237 × 10−4 in the ternary system. The outcome indicated that the addition of ethanol significantly increased the mole fraction of ivermectin in CO2. The highest impact of ivermectin solubility was found in the ivermectin -Ethanol- CO2 system at 338 K and 12 MPa, which was about 14.35 times greater than binary system under the same conditions. The models proposed by Jouyban et al. and Sodeifian-Sajadian models showed the best correlation with average absolute relative deviation (AARD%) and Akaike information criterion (AICc) for binary and ternary approaches, respectively. The results confirmed that rapid expansion supercritical solution (RESS) and gas antisolvent (GAS) method can be apply for producing nanoparticles at the suitable ranges of the drug solubility.

Chirality hierarchical transfer in homochiral polymer crystallization under high-pressure CO2

Ordered phase transitions are commonly correlated to symmetry breaking, while disordered phase transitions are characterized by symmetry restoration. Nevertheless, this study demonstrates that these correlation relations are not always applicable in chiral polymers under high-pressure Carbon Dioxide. Without racemization, homochiral Poly (lactide acid) can generate two vortex-shaped dendritic crystals with opposite spiral chirality, and snowflake-shaped dendritic crystals without spiral chirality. The transition from homochiral molecules to achiral crystals signifies the chiral symmetry restoration during the ordering process. The primary elements responsible for the various hierarchical transfers of homochiral Poly (lactide acid) are related to chain tilt, surface stress, and frustrated structures of Poly (lactide acid) crystals. Here, we show the entropy impact of Carbon Dioxide can be utilized to programmatically regulate the morphological chirality of crystal superstructure and crystal form of homochiral Poly (lactide acid).

Dynamic wetting of a CO2-H2O-montmorillonite system using molecular dynamics

Injecting carbon dioxide into shale reservoirs achieves geological carbon sequestration (GCS), effectively reducing atmospheric carbon dioxide levels. Rock wetting characterizes the strength of the interaction between fluids and rocks, thereby determining fluid distribution, which is crucial for GCS trapping efficiency. In this study, the dynamic wetting of H2O-montmorillonite and CO2-H2O-montmorillonite systems was studied using molecular dynamics (MD) simulations. Montmorillonites with different lattice substitution arrangements based on pyrophyllite are strongly water-wet, and a precursor film forms at the leading edge of the bulk water. Na+ controls precursor film formation, which is rapidly spreading forward at a constant speed along the lattice substitution site lines based on Na+ distribution. The lower the proportion of Al3+/Si4+ lattice substitution in the Si-O tetrahedral layer on the fluid side, the higher the degree of water-wetness. The competitive adsorption of carbon dioxide and water molecules reduces the degree of spreading, resulting in a decrease in the degree of water-wetness. However, compared to the H2O-montmorillonite system, the spreading behavior remained unchanged. High carbon dioxide pressure caused the wetting to change from strongly water-wet to weakly water-wet, however no wetting reversal was exhibited. The wetting changes were particularly prominent near the supercritical carbon dioxide pressure, with a limit of 18 MPa. For the first time, this study distinguished the dynamic behaviors of bulk water and precursor films, revealed the formation mechanism of precursor films, and revealed the control mechanism of carbon dioxide pressure on dynamic wetting from a molecular perspective. The quantitative relationship between the contact angle and flow velocity at different carbon dioxide pressures presented in this study could effectively guide the establishment of a fluid force equation for infiltrating flow, providing theoretical support for GCS numerical simulation research.

Dynamic characteristics of high-pressure and high-density carbon dioxide leakage process

The leakage of high-pressure and high-density carbon dioxide (CO2) during storage and transportation can result in the rapid release of a substantial amount of CO2, presenting significant risks to Carbon Capture and Storage (CCS) technology. Investigating the dynamic characteristics of high-pressure and high-density CO2 leakage in storage tank, as well as understanding the variations in CO2 pressure, temperature, density, and phase during the leakage process, is crucial for the design of tank and pipeline leakage prevention. Existing research mainly focuses on leakage at the top or side of storage tank, there is a lack of attention to leakage from the bottom of storage tank. To simulate the bottom leakage processes, a depressurized experimental system with a 0.065 m3 CO2 storage tank volume was constructed. The range of CO2 parameter conditions for filling density is 811 ∼ 998 kg/m3, with initial pressure ranging from 5.72 ∼ 16.50 MPa. According to the change in the slope of the pressure drop in the storage tank, the leakage can be divided into three processes. The closer to the top of the storage tank, the liquid–gas phase transition of CO2 occurs earlier. The pressure shows two inflection points (point I and point II) representing the upper and lower limits of CO2 saturation pressure, respectively. The lower filling density results in a higher saturation pressure, while the higher initial pressure also leads to a higher saturation pressure. The current work can help to better understand pressure, temperature, density, and phase state changes of CO2 during leakage.

A comprehensive review on novel synthetic foods: Potential risk factors, detection strategies, and processing technologies

AbstractNowadays, the food industry is facing challenges due to the simultaneous rise in global warming, population, and food consumption. As the integration of synthetic biology and food science, novel synthetic foods have obtained high attention to address these issues. However, these novel foods may cause potential risks related to human health. Four types of novel synthetic foods, including plant‐based foods, cultured meat, fermented foods, and microalgae‐based foods, were reviewed in the study. The original food sources, consumer acceptance, advantages and disadvantages of these foods were discussed. Furthermore, potential risk factors, such as nutritional, biological, and chemical risk factors, associated with these foods were described and analyzed. Additionally, the current detection methods (e.g., enzyme‐linked immunosorbent assay, biosensors, chromatography, polymerase chain reaction, isothermal amplification, and microfluidic technology) and processing technologies (e.g., microwave treatment, ohmic heating, steam explosion, high hydrostatic pressure, ultrasound, cold plasma, and supercritical carbon dioxide) were reviewed and discussed critically. Nonetheless, it is crucial to continue innovating and developing new detection and processing technologies to effectively evaluate these novel synthetic foods and ensure their safety. Finally, approaches to enhance the quality of these foods were briefly presented. It will provide insights into the development and management of novel synthetic foods for food industry.

Widely targeted metabolomics analysis reveals the potential metabolic network of high-pressure carbon dioxide regulating fresh-cut Chinese water chestnut yellowing

In this study, we applied widely targeted metabolomics and physiological analysis to investigate the non-volatile metabolites changes and regulatory mechanisms of high-pressure carbon dioxide (HPCD) treatment on the yellowing of fresh-cut Chinese water chestnut (CWC). A total of 349 non-volatile metabolites were identified and subjected to principal component analysis (PCA), OPLS-DA and KEGG enrichment analysis. The results showed that the yellowing of fresh-cut CWC was related to membrane lipid metabolism and flavonoid biosynthesis. Damage stress induced membrane lipid metabolism and flavonoid biosynthesis in surface tissues, and the increase of phenylalanine ammonia-lyase (PAL) activity in flavonoid biosynthesis might be triggered by signaling molecules from membrane lipid metabolism. On the one hand, HPCD treatment could directly inhibit the activity of PAL, and reduce the biosynthesis of flavonoids in the damaged tissues. On the other hand, HPCD could indirectly inhibit the generation and accumulation of potential signaling molecules by regulating membrane lipid metabolism, thus preventing signaling molecules from triggering flavonoid biosynthesis. This study proposed a potential network of HPCD regulating the yellowing of fresh-cut CWC and established the foundation for further control of yellowing in fresh-cut CWC.

Synthesis/separation of 5-hydroxymethylfurfural converted from fructose promoted by H2O–CO2 biphasic system with solid catalysts: Experimental and kinetic modeling approaches

5-Hydroxymethylfurfural (5-HMF) is an industrially valuable compound typically produced by dehydration of fructose converted from cellulosic biomass. However, the formation of 5-HMF is accompanied by its conversion into by-products, such as levulinic and formic acids, decreasing its yield. Therefore, biphasic processes are attracting much attention allowing the efficient simultaneous synthesis and separation of 5-HMF. In this study, a biphasic system using water with high-pressure carbon dioxide, the most environmentally friendly solvents, combining with a solid catalyst is used to achieve 5-HMF synthesis and separation at lower temperatures and shorter duration than previous studies. The main experiment was operated by a semibatch reactor with a continuous flow of CO2. Additionally, three experiments, i) measurement of the partition coefficient of 5-HMF between the two phases, ii) 5-HMF synthesis in H2O–CO2 biphasic batch system, and iii) 5-HMF extraction in H2O–CO2 biphasic semibatch system, were conducted to complement the main experiment. All results from complement experiments were used as parameters in the kinetic modeling. As the result, the maximum yield of 5-HMF (36.6 %) was achieved at a temperature of 403 K, a pressure of 25 MPa, and a reaction time of 180 min. Finally, the optimal conditions for the semibatch experiment for 5-HMF synthesis and separation could be estimated from the kinetic models with parameters determined in this work. The obtained results suggested that this yield can be further improved by increasing the reaction time, which should be confirmed by further experimental studies.

A computational fluid dynamic method for dense-phase carbon dioxide centrifugal pump

As an advanced approach for large-scale low-carbon utilization of fossil energy, the carbon capture, utilization and storage technology is a promising means to achieve the carbon-neutrality target by 2060. Among the most widely used approaches for carbon storage is the enhanced oil recovery technique, for which the centrifugal pump is used to inject high-pressure dense-phase carbon dioxide (CO2) into the stratum. This work focuses on real fluid effects and inter-stage matching deviation from the incompressibility assumption for a dense-phase CO2 centrifugal pump, of which the inlet condition is close to the fluid critical point. With a thermophysical-state table for CO2 based on the thermophysical-property database of the National Institute of Standards and Technology embedded into a computational fluid dynamics solver, a numerical simulation method for compressible dense-phase CO2 pumps is established. The developed method is validated in the 50kW main compressor for a supercritical CO2 cycle and then applied to the simulation of a multistage dense-phase CO2 pump designed for carbon storage. The stage with the most remarkable fluid compressibility is determined, which provides a priori basis for the follow-up design optimization of the pump. This work is of promising application prospect for design of advanced dense-phase fluid machinery.

A new, automated method for the investigation of melting point depression under carbon dioxide pressure

The aim of this work was to develop a new, automated method for the detection of solid-liquid phase transitions in the presence of high-pressure carbon dioxide. This is allowed because of the dissolution of the medium in the sample during the solid-liquid-gas equilibrium measurement. The pressure of an empty reference cell and one containing a solid sample is compared by a differential pressure transmitter. A gradual heating program is conducted after their equal pressurization. The solid-liquid transition of the sample is marked by a sharp decrease in the pressure of the sample holder (compared to the reference cell). A processing algorithm for the recorded time – temperature – pressure-difference data was implemented, to determine the melting temperature range accurately and automatically. The apparatus was validated with racemic ibuprofen and benzoic acid, and provides a new, objective, and easy-to-automate alternative to determine the melting temperature in high-pressure carbon dioxide.

Controlling Polymer Structure with High-Pressure Carbon Dioxide

Controlling Polymer Structure with High-Pressure Carbon Dioxide

Flow rate analysis of high-pressure carbon dioxide through a combinational flow regulator

Flow control is essential in high-pressure CO2 systems. Flow regulators are widely used for flow adjustment in piping systems. In this paper, a novel combinational flow regulator is proposed, which contains four parallel branch channels, and each channel is arranged with a solenoid valve and an orifice plate. In order to analyze the internal flow characteristics of high-pressure CO2 and flow adjustment performance of the proposed flow regulator, a numerical model of the regulator is established, and the validation of numerical model is verified by experimental results. Then, the pressure and velocity characteristics are studied numerically. Finally, the flow adjustment performance is investigated numerically and experimentally from three aspects: variation of flow rate with differential pressure, variation of the product of flow coefficient and throttling area, and dynamic variations of pressure, temperature and flow rate of the flow regulator. This paper serves as a valuable reference for researchers utilizing flow regulators to adjust the flow rate of CO2 or other fluids.

Investigating the steel–cement interface in high-temperature, high-pressure carbon dioxide environments

Abstract This study investigates the impact of high-temperature, high-pressure carbon dioxide on the steel-cement interface, crucial in engineering structures and carbon capture storage systems. Experiments conducted on N80 steel and ordinary portland cement in synthetic aquifer brine revealed that CO2 exposure significantly exacerbates steel corrosion and cement degradation. The corrosion current density of steel increased to 1.2 μA/cm2 after six months in CO2, compared to 0.3 μA/cm2 in unexposed samples. Cement samples showed a marked decline in mechanical properties, with hardness reducing from 1.25 GPa (giga-Pascal) in control samples to 0.65 GPa after six months. The steel—cement interface integrity also diminished, as evidenced by a decrease in acoustic impedance from 45.0 M-Rayl to 34.0 M-Rayl over six months. These results emphasize the need for advanced materials and strategies to enhance the durability and safety of structures in CO2-rich environments.

Valorization of marine by-products using green technology

In this work, two cases of marine by-product valorization using green technologies were highlighted, i.e., utilization of high-pressure carbon dioxide (HPCD) for demineralization of goldstripe sardinella (Sardinella gibbosa) scales and the use of non-specific enzymes for chitosan hydrolysis. After demineralization, type I collagen can be recovered from sardine scales. This work used HPCD process (of up to 10 bar or 1 MPa) to remove minerals from scales instead of the traditional strong acid method. Results from initial phase of the work showed that the process efficiency was significantly affected by pressure applied and treatment time (p < 0.05). And the demineralization efficiency reached was significantly lower than that achieved by treatment with hydrochloric acid (p < 0.05). In the second study, the chitosanolytic activity of four non-specific enzymes were assessed for chitosan hydrolysis. The results indicated that acid protease and cellulase could be a potential choice to produce chitooligosaccharides (COS) from shrimp shell.

Influence of storage conditions, packaging, post-harvest technology, nanotechnology and molecular approaches on shelf life of microgreens

Microgreens have achieved importance recently due to their high nutritive value, easiness of cultivation and year round availability. However, being very tender and having high moisture content, their shelf life is too short. Studies show that the physical quality, chemical quality and shelf life deterioration in post harvest of micro greens can be improved with effective storage conditions, packaging matters, nanoparticle application, physiological treatments and molecular approaches. Low ambient or storage temperature and effective storage system improve and sustain the shelf life, and quality and restrict microbial activity in micro greens. Packaging with bioplastic clamshell, cardboard clamshell, bioplastic pouch, kraft paper box, or classified polymer upgrades the shelf life and reduce antimicrobial activity under controlled temperature. The interventions with nanoparticles such as nano packaging, nano coatings and nano bubble modify the shelf life and quality and forbids microbial outbreak, solvent discharge and unstable gaseous exchange. The real time signal processing nano sensor technology can detect pesticides, pathogens, toxic materials, contaminants, and microbes in microgreens. The emission of light emitting diodes with stable ratio of wavelength extends shelf life. High carbon dioxide and low oxygen pressure at 5 °C temperature exhibits control respiration rate and prolonged shelf life. The standard packaging materials and post harvest technology may be recognized for extending shelf life and quality in harvested microgreens. The integration of molecular tools can be used to screen genome, replication, transcription, translation, post translation and gene regulation for shelf life improvement and desired traits.

Structural Stress Intensity Analysis of Hybrid Heat Exchangers Based on Thermal Hydraulic Performance in S-CO2 Power Cycle

Abstract Hybrid heat exchangers (H2Xs) can be used for heat exchange equipment between high-temperature exhaust gas from ships and high-pressure supercritical carbon dioxide (S-CO2) from the S-CO2 power cycle. We investigate structural stress intensity characteristics of the H2Xs based on thermal-hydraulic performance. Air and S-CO2 are employed as the working fluids and the Stainless Steel 316 (SS316) as the solid substrate. The thermal-hydraulic performance and structural stress intensity characteristics of the H2Xs are conducted by Ansys Fluent and Mechanical, respectively. The results show the mechanical stress induced by pressure loading and the thermal stress induced by temperature gradient are found to be equally important sources of stress intensity. At the inlet and outlet of the H2Xs, the total stress intensity along all paths is not smooth and continuous, and there will be a significant change due to the change in the temperature gradient. The mechanical stress caused by the fluid pressure loss is almost negligible. The change in inlet mass flowrate and temperature mainly affects the stress intensity distribution of the left and right walls on the fin channel. The pressure variation of the diesel engine has little effect on the total stress intensity. Importantly, the total stress intensity of the H2X is mainly affected by the change in S-CO2 fluid pressure.

Accelerating cryoprotectant delivery using vacuum infiltration

The ability to cryopreserve bone marrow within the vertebral body (VB) would offer significant clinical and research benefits. However, cryopreservation of large structures, such as VBs, is challenging due to mass transport limitations that prevent the effective delivery of cryoprotectants into the tissue. To overcome this challenge, we examined the potential of vacuum infiltration, along with carbonation, to increase the penetration of cryoprotectants. In particular, we hypothesized that initial exposure to high-pressure carbon dioxide gas would introduce bubbles into the tissue and that subsequent vacuum cycling would cause expansion and contraction of the bubbles, thus enhancing the transport of cryoprotectant into the tissue. Experiments were carried out using colored dye and agarose gel as a model revealing that carbonation and vacuum cycling result in a 14% increase in dye penetration compared to the atmospheric controls. Experiments were also carried out by exposing VBs isolated from human vertebrae to 40% (v/v) DMSO solution. CT imaging showed the presence of gas bubbles within the tissue pores for carbonated VBs as well as control VBs. Vacuum cycling reduced the bubble volume by more than 50%, most likely resulting in replacement of this volume with DMSO solution. However, we were unable to detect a statistically significant increase in DMSO concentration within the VBs using CT imaging. This research suggests that there may be a modest benefit to carbonation and vacuum cycling for introduction of cryoprotectants into larger structures, like VBs.

Using high pressure solutions of polyfluoroacrylate and CO2 to Seal cement cracks for improved wellbore integrity

Polyfluoroacrylate (PFA) is a hydrophobic and oleophobic polymer that is soluble in high pressure carbon dioxide (CO2). In this study, the ability of PFA-CO2 solutions to greatly reduce the apparent permeability of split or cracked Portland cement cylindrical samples is assessed. The apparent permeability values of confined samples were determined before and after treatment with PFA-CO2 solutions. In four tests, PFA-CO2 solutions were continuously displacing pure CO2 from the cracked cement and the decrease in apparent permeability due to PFA adsorption and wettability alteration was monitored. The lowest apparent permeability cracked cement sample (81 nD) was completely sealed with a very small amount of solution. Samples with initial apparent permeabilities of 89 μD and 29.4 mD exhibited 92% and 99% reductions in permeability, respectively, before the experiments had to be stopped because of the excessively large increase in pressure drop. A 50% reduction in apparent permeability was observed with a 3.80 mD sample. Four other split cement samples (bound together with tape) with an initial apparent permeability in the 9.0–70 mD range were removed from the core holder and immersed in a PFA-CO2 solution for 24 h to allow for PFA adsorption. Then the PFA-CO2 solution was depressurized, allowing for the deposition of additional PFA from the solution within the crack as the pressure fell below the cloud point pressure of the PFA-CO2 solution. These four samples were then confined again in a core holder and apparent permeability reductions of 29–93% were observed. Results from these eight experiments indicates that the more substantial reductions in the nD – mD apparent permeability of the cracked cement correlated to lower initial crack permeability, higher PFA concentration, and slower injection rate of the PFA-CO2 solution into the crack.

Offshore decarbonation of CO2-rich natural gas intensified via gas-liquid membrane contactors with blended aqueous-amines

A battery of high-pressure countercurrent gas-liquid membrane contactors (GLMC) using aqueous-methyl-diethanolamine(39% w/w)-piperazine(5% w/w) solvent is demonstrated for offshore decarbonation of 5MMNm3/d carbon-dioxide-rich natural gas. To accomplish this, a Gas-Liquid Membrane Contactor Unit Operation Extension (GLMC-UOE) was built for HYSYS simulator. Mass/energy balances, pressure-drop, vapor/liquid equilibrium properties are solved by GLMC-UOE with rigorous thermodynamics provided by the HYSYS Acid-Gas Chemical-Solvents Package appropriate for high-pressure carbon dioxide chemical-absorption. GLMC-UOE discretizes a countercurrent GLMC module as a cascade of countercurrent GLMC elements, which are solved via adapted simultaneous corrections of variables. Each GLMC element adopts a multicomponent interfacial heat/mass transfer model based on logarithmic-mean of transmembrane temperature-difference and component fugacity-differences for vapor-to-liquid or liquid-to-vapor transfers. The transferable species comprehend carbon dioxide, methane, ethane, propane, water, methyl-diethanolamine and piperazine. GLMC-UOE was validated against the literature. The process comprises the high-pressure GLMC battery, reboilered low-pressure stripping column, heat exchangers, multi-staged carbon dioxide compression and triethylene-glycol dehydration unit. A stripper heat-ratio of 167.7 kJ/molCO2 was required for solvent regeneration, a value compatible with the literature. The process dispatches dry dense carbon dioxide for enhanced oil recovery in the same offshore field. GLMC-UOE correctly predicts GLMC temperature effects, gas hydration, methane losses in the solvent and pressure-drop.

Molecular dynamics simulation of interaction between high pressure carbon dioxide (HPCD) and phenylalanine ammonia-lyase (PAL)

High-pressure carbon dioxide (HPCD) could effectively suppress the yellowing phenomenon in Chinese water chestnut (CWC) by significantly inhibiting the activity of the key enzyme—phenylalanine ammonia-lyase (PAL). However, the molecular mechanism underlying this inhibition remains unclear. In this study, we investigated the structural changes and inhibition mechanisms of PAL from CWC subjected to HPCD treatment. Homology modeling was used to construct the 3D structure of CWC PAL. The results showed that CWC PAL was highly conserved and had higher α-helix content. Molecular dynamics simulations and molecular docking were utilized to investigate the non-covalent interaction between CO2 and PAL. Our findings revealed that CO2 induced conformational changes in PAL via hydrogen bonds, polar interactions, and hydrophobic interactions, thereby increasing PAL's α-helix structure and preventing the substrate L-Phe from entering its active site. Additionally, HPCD treatment caused the movement of the Phe-111 residue in the inner lid-loop, resulting in steric hindrance and destruction of the active center of PAL. These results provide a theoretical basis for expanding the application of HPCD in the food processing industry.

High-pressure supersonic carbon dioxide (CO2) separation benefiting carbon capture, utilisation and storage (CCUS) technology

Carbon capture, utilisation and storage (CCUS) is of unique significance for building a green and resilient energy system, and it is also a key solution to tackle the climate challenge. The concept of supersonic decarburization, a joint product of non-equilibrium condensation and swirling separation, can contribute to CCUS technology in a clean way. In this paper, a numerical model is established and validated to investigate the complex physical phenomena of supersonic decarbonization in a high-pressure environment based on the real gas equation of state. The model is compatible with the pure CO2 model and CH4-CO2 model. Through the simulation of the supersonic nozzle and supersonic separator, the condensation and separation performance of supersonic decarbonization technology was evaluated. For the condensation performance of carbon dioxide, the results show that higher pressure makes it much easier to achieve the condensation process. When the pressure is supercritical, the decrease of inlet temperature or the increase of inlet mole fraction of CO2 leads to a higher liquid fraction. For separation performance, when the mass concentration of inlet heterogeneous droplets increases from 0.1 kg/m3 to 7.5 kg/m3, the carbon separation amount increases from 3.33 ton/h to 4.43 ton/h, while the exergy loss of condensed CO2 drops from 436.57 kJ/kg to 329.56 kJ/kg. It demonstrates that the decarburization process is easier, and exergy required for condensation decreases when the concentration of the foreign core is larger. This new concept is beneficial to CCUS technology and can be applied to carbon capture in offshore natural gas processing.