SC CO2 Research Articles

Polyprenylated benzophenone-enriched extracts obtained using SC–CO2 from the dry ethanolic extract of Brazilian red propolis

ABSTRACTRed propolis is a well-known potent antimicrobial source because of its various bioactive compounds. This work aims to submit a sample of Brazilian red propolis to supercritical CO2 extraction, with subsequent chemical characterisation by HPLC and UHPLC–MS, and to evaluate the antifungal activity against three strains of Candida glabrata. The method proved to be selective for the extraction of benzophenones. The results demonstrated a correlation between the presence of benzophenones and antifungal activity. The supercritical extract that seems to be the richest in benzophenones was the one obtained with a pressure of 300 bar and was the most active against the C. glabrata strains.Abbreviations: SFE, Supercritical Fluid Extraction; MIC, Minimal Inhibitory Concentration; SC, Supercritical; BZP, benzophenones

Supercritical CO2 uptake by nonswelling phyllosilicates

Interactions between supercritical (sc) CO2 and minerals are important when CO2 is injected into geologic formations for storage and as working fluids for enhanced oil recovery, hydraulic fracturing, and geothermal energy extraction. It has previously been shown that at the elevated pressures and temperatures of the deep subsurface, scCO2 alters smectites (typical swelling phyllosilicates). However, less is known about the effects of scCO2 on nonswelling phyllosilicates (illite and muscovite), despite the fact that the latter are the dominant clay minerals in deep subsurface shales and mudstones. Our studies conducted by using single crystals, combining reaction (incubation with scCO2), visualization [atomic force microscopy (AFM)], and quantifications (AFM, X-ray photoelectron spectroscopy, X-ray diffraction, and off-gassing measurements) revealed unexpectedly high CO2 uptake that far exceeded its macroscopic surface area. Results from different methods collectively suggest that CO2 partially entered the muscovite interlayers, although the pathways remain to be determined. We hypothesize that preferential dissolution at weaker surface defects and frayed edges allows CO2 to enter the interlayers under elevated pressure and temperature, rather than by diffusing solely from edges deeply into interlayers. This unexpected uptake of CO2, can increase CO2 storage capacity by up to ∼30% relative to the capacity associated with residual trapping in a 0.2-porosity sandstone reservoir containing up to 18 mass % of illite/muscovite. This excess CO2 uptake constitutes a previously unrecognized potential trapping mechanism.

Corn Lecithin for Injection from Deoiled Corn Germ: Extraction, Composition, and Emulsifying Properties

Although the lipid fraction of corn germ is rich in lecithin, this material is usually discarded with the residual pulp during industrial corn oil extraction processes. In this study, corn germ, after deoiling by supercritical carbon dioxide (SCCO2), is used as a raw material to prepare corn lecithin for injection. The physicochemical properties, phospholipid composition, fatty acid composition, and emulsifying properties of the corn lecithin for injection is analyzed. The phospholipid and phosphatidylcholine contents in the prepared corn lecithin are 95.96% and 78.37%, respectively. Linoleic acid (45.99%) and oleic acid (22.31%) is the main unsaturated fatty acids, and the ratio of n‐6 polyunsaturated fatty acids (PUFA) to n‐3 PUFA (i.e., n‐6/n‐3) of 6.00 is in accord with World Health Organization recommendations. Emulsions stabilized with the corn lecithin for injection is optically characterized and microscopically inspected, and the droplet size distribution is determined. The results shows that an increase in the corn lecithin concentration lead to a decrease in droplet diameter and an increase in emulsion stability. Furthermore, the corn lecithin for injection creates a more stable emulsion than injection‐grade egg yolk lecithin.Practical Applications: The use of lecithins as emulsifiers for parenteral emulsions was advocated because these materials, typically obtained from egg yolks or soybeans, can be readily metabolized. In this study, we explore the possibility of recovering an important value‐added substance, corn lecithin for injection, which is separated from the corn germ waste generated during corn oil production. The corn lecithin for injection has excellent potential for use as a natural emulsifier in the pharmaceutical, food, and cosmetics industries.In this study, the possibility of preparing high purity corn lecithin for injection from corn germ that is deoiled by supercritical carbon dioxide (SCCO2) is examined. The physicochemical properties, phospholipid composition, fatty acid composition, and emulsifying properties of the corn lecithin for injection is analyzed. Through these efforts, a valuable by‐product of corn oil manufacture is recovered that serves as an attractive, alternative source of injection‐grade lecithin for a wide variety of industrial uses.

An Effective Catalytic Hydroboration of Alkynes in Supercritical CO2 under Repetitive Batch Mode

AbstractA facile method for the synthesis of unsaturated organoboron compounds by hydroboration of terminal and internal alkynes in supercritical (sc) CO2 has been presented for the first time. The reactions performed in scCO2 in the presence of Ru catalysts (selectivity, productivity) are compared with those in a traditionally used solvent or without it. Moreover, the catalytic systems based on the application of scCO2 have been successfully tested for the processes under repetitive batch conditions. This strategy permitted us to obtain boryl‐substituted olefins with high yields and selectivities up to the 16th catalytic cycle if using Ru(CO)Cl(H)(PPh3)3 as a catalyst. The process applied the self‐dosing catalyst, which is gradually released to the reaction mixture under supercritical conditions in the individual batch. Such an approach has a positive impact on process sustainability and economy.

Solubility Determination and Correlation of Gatifloxacin, Enrofloxacin, and Ciprofloxacin in Supercritical CO2

The solubilities of gatifloxacin, enrofloxacin, ciprofloxacin in SC–CO2 were determined by the dynamic method under pressures of 12–36 MPa and temperature of 313, 323, and 333 K. The consistency of the resulting solubility data was verified by the Mendez-Santiago and Teja model, Chrastil model, Bartle model, and K-J model and these models give comparable AARDs (between 6.70% and 13.51%). The compressed gas model and modified expanded liquid model were also used to correlate the resulting solubilities of the three fluoroquinolone drugs. By introducing the reference solubility and calculating the fugacity coefficient of the solute using the Carnahan–Starling-VDW hard sphere equation of state (CS-VDW EoS), the compressed gas model gives the AARDs between 0.86% and 23.65%. The intrinsic proximity of the model parameters in this model is also confirmed for the structurally similar fluoroquinolone drugs. This intrinsic proximity can be used in mutual solubility prediction between the fluoroquinolone drugs once the reference solubilities were known. The modified expanded liquid model gives the AARDs between 10.88% and 16.65% in solubility correlation. However, the predictive capability of the modified expanded liquid model based on the group contribution method needs to be improved further.

Qualitative and Quantitative Changes of Carbonate Rocks Exposed to SC CO2 (Basque-Cantabrian Basin, Northern Spain)

This study aims at the qualitative and quantitative determination of porosity, mineralogical and textural changes in carbonate rock samples after injection of (i) supercritical CO2-rich brine and (ii) dry supercritical CO2, under similar experimental conditions (P ≈ 75 bar, T ≈ 35 °C, 970 h exposure time and no CO2 flow). The studied rocks were sampled in the western Basque-Cantabrian Basin, North Spain, and consist of vuggy carbonates (“Carniolas”) of the Puerto de la Palombera formation (Hettangian). Mineralogical and pore space characterization is completed using optical microscopy, scanning electron microscopy and optical image analysis. In addition, X-ray fluorescence analyses are performed to refine the mineralogical information and to obtain whole rock geochemical data and the brine composition is analysed before and after the experiment. Mineralogical and chemical results indicate that the carbonate rocks exposed to supercritical CO2 in dry conditions do not suffer significant changes. However, the injection of supercritical CO2-rich brine induces chemical and physical changes in the rock due to the high reactivity of calcite at the low pH conditions produced by the acidified brine. Numerical modelling validates the experimental observations. These results can be used to characterize the behaviour of carbonate rocks under conditions similar to the vicinity of a CO2 injection well. The results should be considered only at the scale of the studied samples and not at reservoir scale.

Bimetallic blends and chitosan nanocomposites: novel antifungal agents against cotton seedling damping-off

Phytopathological studies of chitosan nanocomposites are mainly focused on in vitro efficiency, so it is essential to perform a complementary greenhouse assay to find eco-friendly alternatives for plant disease management. In the present study, Cu-chitosan and Zn-chitosan nanocomposites were prepared by reduction of metal precursors in the presence of chitosan in sc CO2 medium and deposition of organosol on chitosan, respectively. Physicochemical properties of the nanocomposites were characterized by X-ray fluorescence analysis (XRF), Small angles X-ray Scattering (SAXS), X-ray Photoelectron spectroscopy (XPS), and Transmission electron microscopy (TEM). The bimetallic blends (BBs) based on nanoscale Cu(OH)2 were obtained through simple precipitation and grinding methods. In vitro and in vivo studies of the antifungal activity of Cu-chitosan, Zn-chitosan and BBs at concentrations of 30, 60, and 100 μg ml−1 were conducted against two anastomosis groups of Rhizoctonia solani for control of cotton seedling damping-off. Effect of metal-chitosan nanocomposites at 100 μg ml−1 combined with Cu-tolerant Trichoderma longibrachiatum strains was also evaluated for control of cotton seedling damping-off under greenhouse conditions. The BBs and Cu-chitosan nanocomposite showed the highest antifungal efficacy against both anastomosis groups of R. solani in vitro. These results indicated that BBs, Cu-chitosan nanocomposite, and BBs combined with Trichoderma may suppress cotton seedling disease caused by R. solani in vivo. The evaluation of R. solani in a greenhouse with a Trichoderma strain showed synergistic inhibitory effect with BBs. Light micrographs of mycelia treated with BBs showed the disruption of the hyphal structures. The interaction of the nanocomposites with DNA isolated from the exposed fungal cells, by means of bonding and/or degradation, was also investigated. DNA interaction in terms of binding and degradation for treated DNA with BBs and chitosan nanocomposites was demonstrated. The results showed the absence of DNA amplification by a microsatellite primed PCR.

Inclusion of connate water in enhanced gas recovery reservoir simulations

Enhanced natural gas recovery (EGR) with supercritical (sc)CO2 sequestration offers the prospect of increased natural gas recovery. High-fidelity reservoir simulations offer a method to quantify the risk of contamination of produced gas by the injected scCO2. Simulations of scCO2 mixing with the reservoir gas have been reported; however the effects of connate water on EGR have not been effectively explored. We extend a prior EGR simulation tool (Patel, May and Johns, 2016; Ref. [1]) to incorporate connate water accounting for its effect on dispersivity and permeability; chemical equilibrium is modelled using a novel, computationally efficient Lagrange multiplier-based approach.The code is applied to a ‘quarter five-spot’ benchmark scenario. The inclusion of connate water generally resulted in a reduction in breakthrough time and a decrease in methane recovery. The connate water's largest effect was to change the scCO2 flow field, which sank towards the reservoir floor, flooded the lowermost accessible layers and entered the production well via a high throughput channel (‘coning’). The magnitude of these effects were, however, sensitive to well perforation depth, the influence of which was subsequently studied systematically. Well perforation depth was found to determine the duration of these sinking and coning events in a non-linear manner.

Durable crosslinked omniphobic coatings on textiles via supercritical carbon dioxide deposition

A novel method of creation durable water- and oil- repellent coatings on flexible substrates (such as textiles) by simultaneous deposition of perfluoroalkyl methacrylate/hydroxyalkyl methacrylate statistical copolymers with a diisocyanate crosslinking agent from solutions in supercritical carbon dioxide (SC CO2) is proposed. The morphology of fluropolymer films deposited on nylon fibers from 1,1,2- trichlorotrifluoroethane and from SC CO2 with/without hexamethylene diisocyanate as a crosslinking agent is compared using scanning electron microscopy. Repellent properties of the films are analysed by water contact angle measurements and by performing standard water spray test as well as hydrocarbon resistance tests before and after multiple home laundry cycles. Enhanced uniformity of the SC CO2 deposited coatings results in improved durability and liquid repelling properties in comparison to coatings deposited from a liquid solvent.

Wettability impact on supercritical CO2 capillary trapping: Pore‐scale visualization and quantification

AbstractHow the wettability of pore surfaces affects supercritical (sc) CO2 capillary trapping in geologic carbon sequestration (GCS) is not well understood, and available evidence appears inconsistent. Using a high‐pressure micromodel‐microscopy system with image analysis, we studied the impact of wettability on scCO2 capillary trapping during short‐term brine flooding (80 s, 8–667 pore volumes). Experiments on brine displacing scCO2 were conducted at 8.5 MPa and 45°C in water‐wet (static contact angle θ = 20° ± 8°) and intermediate‐wet (θ = 94° ± 13°) homogeneous micromodels under four different flow rates (capillary number Ca ranging from 9 × 10−6 to 8 × 10−4) with a total of eight conditions (four replicates for each). Brine invasion processes were recorded and statistical analysis was performed for over 2000 images of scCO2 saturations, and scCO2 cluster characteristics. The trapped scCO2 saturation under intermediate‐wet conditions is 15% higher than under water‐wet conditions under the slowest flow rate (Ca ∼ 9 × 10−6). Based on the visualization and scCO2 cluster analysis, we show that the scCO2 trapping process in our micromodels is governed by bypass trapping that is enhanced by the larger contact angle. Smaller contact angles enhance cooperative pore filling and widen brine fingers (or channels), leading to smaller volumes of scCO2 being bypassed. Increased flow rates suppress this wettability effect.

Microbial potential for carbon and nutrient cycling in a geogenic supercritical carbon dioxide reservoir.

SummaryMicroorganisms catalyze carbon cycling and biogeochemical reactions in the deep subsurface and thus may be expected to influence the fate of injected supercritical (sc) CO2 following geological carbon sequestration (GCS). We hypothesized that natural subsurface scCO2 reservoirs, which serve as analogs for the long‐term fate of sequestered scCO2, harbor a ‘deep carbonated biosphere’ with carbon cycling potential. We sampled subsurface fluids from scCO2‐water separators at a natural scCO2 reservoir at McElmo Dome, Colorado for analysis of 16S rRNA gene diversity and metagenome content. Sequence annotations indicated dominance of Sulfurospirillum, Rhizobium, Desulfovibrio and four members of the Clostridiales family. Genomes extracted from metagenomes using homology and compositional approaches revealed diverse mechanisms for growth and nutrient cycling, including pathways for CO2 and N2 fixation, anaerobic respiration, sulfur oxidation, fermentation and potential for metabolic syntrophy. Differences in biogeochemical potential between two production well communities were consistent with differences in fluid chemical profiles, suggesting a potential link between microbial activity and geochemistry. The existence of a microbial ecosystem associated with the McElmo Dome scCO2 reservoir indicates that potential impacts of the deep biosphere on CO2 fate and transport should be taken into consideration as a component of GCS planning and modelling.

CO2‐Assisted Solution‐Phase Selective Assembly of 2D WS2‐WO3⋅H2O and 1T‐2H MoS2 to Desirable Complex Heterostructures

AbstractPrecise control of the lateral and vertical integration of two‐dimensional (2D) heterostructures is exciting for novel electronic and photovoltaic applications. Fabricating assemblies of high‐quality heterostructures with desirable compositions and sequences is challenging. In this work, with the assistance of supercritical CO2 (SC CO2), we successfully prepared the complex heterostructures of WS2‐WO3⋅H2O/1T‐2H MoS2 with selective stacking assembly. Thanks to the unique properties of SC CO2, which can help to construct a unique solvent system where the hydrophilic or hydrophobic structure for the 2D layer heterostructure can be chosen, 2H‐WS2/2H‐MoS2 assemblies are formed efficiently as the preferred van der Waals heterojunctions. A superior photoelectrochemical activity toward hydrogen evolution based on such the quaternary heterostructures is achieved due to their strong interlayer electronic coupling as well as the increased conductivity and active sites in the heterostructures.

Supercritical CO2-assisted phase transformation from orthorhombic to hexagonal MoO3

The metastable hexagonal phase of molybdenum oxide (h-MoO3) have drawn much attention due to the novel one-dimensional tunnel structure and enhanced properties in physical, optical, chemical and electronic fields. Most of the researchers focused on the hydrothermal reaction to obtain h-MoO3 using NH4+, Na+ or K+ ion as the structure-directing agents and stabilizer of the h-MoO3, which will definitely hinder the further application of h-MoO3. In this work, for the first time, we demonstrate a novel top-down method to obtain metastable h-MoO3 via a topotactic phase transformation with the assistance of supercritical carbon dioxide (SC CO2). Our study indicates that this successful phase transformation is due to distortion of MoO6 octahedra units that might be induced by the surface tension change.

Wettability effects on supercritical CO2–brine immiscible displacement during drainage: Pore-scale observation and 3D simulation

Wettability is an important factor controlling the displacement of immiscible fluids in porous media and therefore affects the flow and transport of supercritical (sc) CO2 in geologic carbon sequestration. Because few studies have focused on the wettability effect in scCO2-brine flow systems, we experimentally and numerically tested influences of wettability on drainage at the pore network scale. Using a high-pressure micromodel-microscopy system, we performed experiments of scCO2 invasion into brine-saturated water-wet and intermediate-wet micromodels, and recorded the scCO2 invasion morphology under reservoir relevant conditions. We also performed pore-scale numerical simulations to infer 3D details of fluid–fluid displacement processes. During drainage under intermediate-wet conditions, we found higher scCO2 saturation, wider scCO2 fingering, and more compact displacement patterns. The simulation results are qualitatively consistent with the experiments. Through quantitative analyses of the experiments, we found that the reduced wettability decreases the displacement front velocity, promotes non-wetting phase pore-filling events in the longitudinal direction, delays the breakthrough time of invading fluid, and increases the displacement efficiency. Simulated results also show that the fluid–fluid interface area follows a unified power-law relation with scCO2 saturation, and show smaller interface area in intermediate-wet case which suppresses the mass transfer between the phases. These pore-scale results provide insights for the wettability effects on CO2–brine immiscible displacement in geologic carbon sequestration.

Supercritical CO2‐Assisted Reverse‐Micelle‐Induced Solution‐Phase Fabrication of Two‐Dimensional Metallic 1T‐MoS2 and 1T‐WS2

AbstractMetallic 1T phase molybdenum disulfide (MoS2) and tungsten disulfide (WS2) are both expected to exhibit promising catalytic activity, but they are highly unstable in nature. Exploring an efficient route to fabricate a high ratio of 1T‐MoS2 and 1T‐WS2 is highly desirable. Herein, for the first time, we report a two‐step process for synthesizing stable two‐dimensional (2D) metallic 1T phase MS2 nanosheets in the reverse‐micelle‐induced emulsion microenvironment with the assistance of supercritical CO2 (SC CO2). TEM, Raman and XPS characterizations demonstrate that the as‐prepared MoS2 nanosheets consist of 1T‐ and 2H‐phase, and the content of 1T phase is more than 90 %. The obtained 1T‐MoS2 exhibits excellent stability and good activity for the hydrogen evolution reaction. A potential of ≈330 mV at a current density of 10 mA cm−2 and a Tafel slope of 70 mV per decade were obtained for 1T‐MoS2. TEM and UV/Vis spectrum characterizations also testify that we have obtained 1T‐WS2. Thus this strategy utilizing a reverse‐micelle‐induced method for fabrication of 2D 1T‐MS2 can widen the potential applications in photoelectrocatalysis and photoelectronic devices.

Fabrication and assembly of two-dimensional TiO2/WO3·H2O heterostructures with type II band alignment for enhanced photocatalytic performance

The recombination of photo-induced charges is one of the main issues to limit the large-scale applications in photocatalysis and photoelectrocatalysis. To improve the charge separation, we fabricate a novel type II 2D ultrathin TiO2/WO3·H2O heterostructures with the assistance of supercritical CO2 (SC CO2) in this work. The as-fabricated heterostructures possess high photocatalytic activity for the degradation of methyl orange(MO) and high photocurrent response under simulated solar light (AM 1.5). For the TiO2/WO3·H2O heterostructures, the MO solution could be degraded by 95.5% in 150min, and the photocurrent density reaches to 6.5μAcm−2, exhibiting a significant enhancement compared with pure TiO2 and WO3·H2O nanosheets.

Dyeing of cotton fabric with reactive disperse dye contain acyl fluoride group in supercritical carbon dioxide

Reactive disperse dyes with mono- and bi-acyl fluoride reactive groups have been synthesized using a simple and convenient method. The structures of these dyes have been defined by 1H, 13C and 19F NMR. The cotton dyeing in supercritical carbon dioxide (Sc CO2) with dyeing temperature varying from 60 °C to 120 °C and time between 1 h and 3 h and with the concentration of 0.5% owf (on weight of fabric) have been studied. Significant improvement of the color fastness of washing and rubbing has been observed owing to the covalent bond formed between the reactive group of dyes and the functional group of cotton fibers. Besides, the dyed fabrics possess favorable fastness properties, indicating the achievement of lower-temperature dyeing of cotton in Sc CO2. Additionally, the end products meet the garment dyeing standards as well. A mechanism of dyeing process is tentatively speculated meanwhile.

Some thermodynamic processes of anthracite–carbon dioxide mixture in supercritical fluid state

In the context of the development of the catalyst regeneration procedure via supercritical fluid CO2 extraction, some thermodynamic properties of the anthracene–carbon dioxide mixture in supercritical fluid state have been studied. Data on anthracene solubility in pure and modified (dimethyl sulfoxide, 5 wt %) supercritical carbon dioxide (SC–CO2), the heat capacity of anthracene and its mixtures with carbon dioxide, and the heat of solution of anthracene in SC–CO2 are presented. Anthracene solubility in SC–CO2 is described satisfactorily using the Peng–Robinson equation of state.

Conformational lability of ibuprofen in supercritical carbon dioxide

A study of conformational equilibria of ibuprofen in vacuum and supercritical carbon dioxide (SC CO2) was carried out using methods of quantum chemistry and molecular dynamics simulation. It was found that ibuprofen forms 12 different conformations in SC CO2, two of them correspond to the structure of the molecule in the crystal lattice of the first and second polymorph. It was shown that the GAFF force field allows one to obtain the characteristics of conformers, almost coinciding with those obtained by quantum chemical calculations at the B3LYP/cc-pVTZ level of theory.

An investigation of the dissolution of acetylsalicylic acid in supercritical carbon dioxide

The dissolution of acetylsalicylic acid in supercritical carbon dioxide (SC–CO2) is investigated using Fourier transform IR spectroscopy. Temporal dependences of integrated intensities of the absorption band of acetylsalicylic acid (ASA) near 1199 cm–1 are measured for various ASA charges placed into a cuvette. Molar fractions of ASA in the saturated solution in SC–CO2 are determined at a temperature of 40°C and pressures of 10.0 and 15.0 MPa, and the components are 2.10 ± 0.25 × 10–4 and 11.0 ± 1.5 × 10–4, respectively.