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Accurate measurement and prediction of the phase behaviour of mixtures involved in a chemical process are crucial for its optimisation. Given the importance of CO 2 conversion technologies and considering possible benefits of CO 2 -ionic liquid biphasic systems, i.e., facilitating a product separation, we investigated the high-pressure behaviour of components of interest in a recently developed process of cyclic carbonate synthesis directly from CO 2 and potentially bio-based alcohols. The solubility of 1,2-butanediol and 1,2-butylene carbonate in a dense carbon dioxide phase was determined experimentally at the temperature of 313.2 K and pressures between 6 and 18 MPa. The influence of 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ionic liquid, [hmim][FAP], as a solvent, on the solubility of these compounds in CO 2 -rich phase, in ternary (CO 2 + 1,2-butanediol + [hmim][FAP]), CO 2 + butylene carbonate + [hmim][FAP]) and quaternary (CO 2 + 1,2-butanediol + butylene carbonate + [hmim][FAP]) mixtures was investigated. The experimental results of the two binary systems were correlated using the density-based Chrastil equation. The knowledge of phase equilibria behaviours reported in this work will be useful for designing chemical conversions of carbon dioxide using [hmim][FAP] ionic liquid as reaction solvents. [Display omitted] • solubility of 1,2-butanediol and butylene carbonate in dense CO 2. • phase behaviour of ternary and quaternary CO 2 -IL biphasic mixtures. • 1-hexyl-3-methylimidazolium tris(pentafluoroalkyl)trifluorophosphate ionic liquid as solubility modifier. [ABSTRACT FROM AUTHOR]

High-pressure carbon dioxide switchable solution with 1,8-diazabicyclo [5.4.0] undec-7-ene (DBU) and ethylene glycol (EG) was applied for a dissolution and modification of cellulose derived from a cassava pulp waste. The switchable solution of DBU and EG were formed by adding carbon dioxide under a pressure range of 0.1–10.0 MPa and a temperature range of 298 and 333 K. The cellulose was dissolved into the CO 2 switchable system at a pressure of 0.1 and 5.8 MPa and a temperature of 313 K. The precipitates of bicarbonate salt of reaction between DBU and carbon dioxide were observed in the switchable solution at the higher pressures and lower temperatures. The cellulose was also modified in the switchable solution with the ionized DBU, EG and carbon dioxide as analyzed by Fourier transform infrared spectroscopy. The modified cellulose was then utilized for the fabrication of the transparent film. [ABSTRACT FROM AUTHOR]

Abstract: A novel carbonation route for the synthesis of CaCO3 is reported with high pressure CO2 scintillated into dry Ca(OH)2 powder containing a solid ionic liquid (SIL, tetra-n-heptyl-ammonium bromide). Results show that calcite structure with rhombohedral lattice is produced at all CO2 conditions investigated: supercritical (15.0MPa, 50.0°C), compressed (5.0MPa, 30.0°C), liquid (15.0MPa, 25.0°C), gaseous (0.1MPa, 30.0°C) and atmospheric (0.1MPa, 30.0°C). Furthermore, rapid and complete conversion is achieved under the supercritical condition with the production of nano-sized calcite particles, suggesting that coupling SIL with CO2 could be an effective system for enhancing traditional gas–solid reactions. A mechanism for the rapid gas–solid carbonation reaction is proposed with emphasis on the initialization of the reaction by tiny adsorbed water and CO2 dissolved in the SIL. [Copyright &y& Elsevier]

Abstract: High-pressure carbon dioxide (HPCD) treatment is currently considered as an attractive non-thermal process for preserving food. Since the first level of interaction between HPCD and the bacterial cells is lowering of the pH, knowledge of the pH of a food product in contact with CO2 at high-pressure conditions is essential for a better understanding of the inactivation mechanism of HPCD. Therefore, a mathematical model was developed to predict the pH in complex aqueous food systems in contact with CO2 at high-pressure conditions as function of pressure, temperature and buffer capacity. In addition, a spectrofluorometric method using calcein as fluorescent pH indicator was designed for the in situ measurement of the pH of complex aqueous systems in contact with pressurized CO2 as function of pressure (10.5–18.0MPa), temperature (25–35°C), initial pH (4.0–8.0), working volume ratio (41.6–70.0%) and broth composition (0.1M citrate buffer, 0.1M phosphate buffer and 10% whey protein). To mimic a complex matrix, the bacterial Brain Heart Infusion (BHI) broth was used. In general, there was a good agreement between the measured and predicted pH values. Only for the lowest initial pH of the broth, a discrepancy between the measured and calculated pH values was noticed, implying that the proposed model needs some further refinement to properly take into account non-ideality of the liquid phase. Furthermore, the pH of the broth was significantly influenced by the initial pH of the solution but was not dependent on pressure, temperature and working volume ratio. The addition of complementary buffers to the broth also influenced the pH drop and this effect was dependent on the initial pH of the solution. [ABSTRACT FROM AUTHOR]

Abstract: The effect of hydrogen partial pressure on the hydrogenation of limonene in high-pressure carbon dioxide, catalysed by carbon-supported palladium, was studied. Experiments were performed at various hydrogen pressures in the range from 2.5 up to 4.4MPa at a fixed total pressure of 12.5MPa, where the reaction mixture remains biphasic—liquid+gas. In these conditions, the liquid phase volume is expanded in relation to the initial volume of limonene in a fashion that is strongly dependent on the hydrogen to carbon dioxide pressure ratios. Surprisingly, the main factor in the kinetics of hydrogenation turns out to be the concentration (moldm−3) of limonene, which decreases due to the volumetric expansion of the liquid phase when the CO2 pressure increases. [Copyright &y& Elsevier]

Abstract: The change of pressure, temperature and phase during high-pressure carbon dioxide explosion process were investigated. Different initial temperature and pressure conditions were chosen, ranging from 25 to 65°C and 500 to 3000psi covering initial liquid, supercritical and gas phases. Under certain initial conditions with low temperature and high pressure, the depressurization process caused a phase change that increased the release time where the depressurization–time curves did not exponentially decrease. This explosion process was characterized based on total release time, rate of depressurization, and effect of phase change on the rate of depressurization. The temperature change associated with the change of pressure was also discussed. Canola flakes were exploded using chosen initial conditions. Oil extraction from canola flakes using supercritical carbon dioxide was improved after explosion treatment. Explosion at 35°C and 3000psi of initial condition resulted in the highest oil yield. [Copyright &y& Elsevier]

Abstract: Sterility is required for medical devices use in invasive medical procedures, and for some situations in the food industry. Sterilization of heat-sensitive or porous materials or devices, such as endoscopes, porous implants, liquid foodstuff, and liquid medicine, poses a challenge to current technologies. There has been a steady interest in using high-pressure carbon dioxide as a process medium for new sterilization technology. Among the potential advantages are that CO2 may sterilize at low temperatures. This paper is a review of the technical and patent literature, including analysis of the microorganisms studied, important operating parameters, and deactivation mechanisms. The current research status and challenges are summarized at the end of this paper. [Copyright &y& Elsevier]

• Seeds were treated after equilibration to a w 0.75 and soaking. • HPCD reduced fungi and bacteria on oats, and barley grains, soy and mung beans. • Salmonella was more resistant than Escherichia coli. • HPCD prevented growth of A. niger and P. roqueforti for 10 d after treatment. • More than 90% of mung beans germinated after treatment. [Display omitted] Decontamination of low a w foods without impairing the food quality is challenging, particularly for sprouting seeds. This study aimed to explore the lethality of high pressure carbon dioxide (HPCD) to Salmonella enterica , E. coli AW1.7, A. niger, P. roquforti , and Fusarium on beans, cereal grains, and ground pepper. The optimal antimicrobial effect of HPCD was achieved by equilibration of the a w to 0.75, followed by soaking in water and treatments with water-saturated CO 2. HPCD reduced the viable cell counts of E. coli and Salmonella by 3–10 log(CFU/g) , and prevented fungal growth during 10 d of incubation. More than 90% of mung beans germinated but the germination of oats was impaired after fungicidal or bactericidal treatments with HPCD. Overall, HPCD can be a promising antimicrobial treatment but treatment parameters need to be optimized for each type of seed. [ABSTRACT FROM AUTHOR]

• An innovative dairy product was processed using supercritical technology. • Effects of pressure, temperature and CO 2 volume ratio were studied. • Temperature and CO 2 volume ratio showed a significant effect on phase separation kinetics. • Pressure influenced only the whey beverage microstructure. The effects of supercritical CO 2 technology on the non-thermal processing of soursop (Annona muricata L.) whey beverage enriched with inulin, a prebiotic carbohydrate, were analyzed. The functional dairy beverage was processed employing different supercritical process conditions: 35 and 55 °C, 10 and 20 MPa, and a CO 2 volume ratio of 20 and 50%. Physicochemical properties (pH, soluble solids, ζ-potential), microstructural characteristics (microstructure, particle size distribution), rheological behavior, color parameters and phase separation kinetics were evaluated. Our results demonstrated that this emerging technology did not promote physicochemical and color changes in the prebiotic whey beverage processed. The temperature and CO 2 volume ratio showed a significant effect on rheological behavior, microstructure, and kinetic stability, while pressure influenced only the beverage's microstructure. Supercritical CO 2 technology can be used as a promising non-thermal treatment for the production of dairy beverages, however, the combination with another homogenization technique may improve the beverage kinetic stability. [ABSTRACT FROM AUTHOR]