Journal of Supercritical Fluids最新文献

This paper corroborates the capability of supercritical water to generate active hydrogen that interact with the different fractions involved in unconventional feedstocks such as oil shale during the hydrothermal reactions by using supercritical deuterated water (SCDW). Experiments were conducted in an autoclave reactor at a temperature of 380 ºC and a time of 1–12 h. The products were assessed using various methods. The findings indicate that 15.30% of deuterium (D) was involved in the reaction of synthetic oil production and that oil samples are characterized by the presence of heteroatoms (N and O) most derived from kerogen. It found that the generation of synthetic oil is perturbed by carbonate species and a maximal yield of 16.78% is reached at 6 h. FTIR revealed that during hydrothermal upgrading of oil shale, the conversion of resins consumes more molecules of D than asphaltenes. According to EPR, Fe²⁺ and Mn²⁺ particles haven't played much role in the upgrading process.

Phase equilibria data for multicomponent mixtures containing methane, propane, carbon dioxide, methanol, water, 2,2′-(Ethane-1,2-diylbis(oxy))diethanol) or triethylene glycol at high-pressure conditions typical to natural gas treating and transportation systems are not readily available in the literature. These data are essential as they contribute to the information required for the process design, control and monitoring of methanol and/or TEG in gas conditioning systems. In this study, new phase equilibria data were measured and modelled for methane + propane + methanol + water + TEG and methane + propane + carbon dioxide + methanol + water + TEG systems over a temperature range of 283.15–323.15 K and pressures up to 14 MPa. The static synthetic method was utilised for the P-T-x measurements and the data were modelled using the Cubic Plus Association model. The modelling approach included regression of binary interaction parameters for relevant binary pairs.

Sterilization using supercritical carbon dioxide has been proven to be efficient for decades now. The aim of this work was to implement a process of sterilization adapted to thermosensitive polymeric materials and highlight the lowest conditions of pressure and temperature which would enable a bacterial reduction higher than 6-log. Inactivation experiments were performed on spores of Bacillus subtilis over a pressure range lying from 60 to 200 bar, and a temperature varying from 35° to 60°C, with and without additive. Preliminary experiments allowed us to determine a restricted experimental domain used for the design of the experiments, investigating the influence of pressure, temperature, process duration, and additive content on bacterial reduction. It was shown that sterilization conducted at 110 bar, 40 °C, for 20 min with 200 ppm of H₂O₂, leading to a bacterial reduction of 8.73-log, may be considered as optimal for IMD sterilization.

In this study, three N,4-dialkyl-substituted 1,8-naphthalimide fluorescent dyes (NPBA, NPHA, and NPOA) were synthesized in supercritical carbon dioxide (scCO₂) by reacting 4-bromo-1,8-naphthalic anhydride with three amines (n-butylamine, n-hexylamine, and n-octylamine). The optimal reaction conditions and highest yields of these dyes were obtained. The yield of NPHA was 92% ± 0.57% using an organic solvent-free synthetic method. The results also indicate that the reaction time was gradually shortened by elongating the alkyl chain in the amines, and the required reaction pressure was 12 MPa or lower. Additionally, the dyeing of polyester fabrics with these three dyes was investigated using scCO₂. The optimal dyeing time and temperature for NPBA were 70 min and 150 ℃, but they decreased at 10 gradients with the addition of two carbon atoms to the alkyl chain in the amines. The optimal dyeing pressure increased from 20 MPa to 24 MPa.

A cocrystal of niclosamide and urea was attempted for the first time using a crystallization in supercritical solvent (CSS). Experiments were conducted at 40 °C or 60 °C between 3.3 and 29.4 MPa in CO₂. Cocrystal formation showed a dependence on the state of CO₂ with no cocrystal formation below the critical point and consistently showed partial conversion above the critical point. The addition of 0.5 mL (2.7–3.5 mol%) cosolvent was found to have significant impact on cocrystal formation at 40 °C and 20 MPa. Addition of 2-propanol increased cocrystal formation by between 50 % and 60 % compared to neat scCO₂, while cyclohexane reduced cocrystal formation by between 20 % and 35 %, and water completely hindered cocrystal formation. The impact of hold time, cosolvent, solubility in relation to ternary phase diagrams, and inter- and intra-molecular hydrogen bonding are discussed.

This study investigated the interactions of lentil protein concentrate (LPC) and pectin hydrogels and their influence on the physico-chemical characteristics of aerogels. First, emulsion gels were formed using high-intensity ultrasound (HIUS) and the impact of HIUS nominal power, and concentrations of LPC and pectin on the gelation were evaluated. Then, the emulsion gels were dried using supercritical CO₂ (SC-CO₂) and the density, surface area, crystallinity index, microstructure and oil and water absorption capacities of the aerogels formed were evaluated. Overall, there was no significant effect of HIUS power on the viscoelastic behavior of the emulsion gels. The emulsion gels exhibited shear-thinning behavior and had thermo-reversible property. The FT-IR spectra of the aerogels showed predominant β-sheets, responsible for the non-covalent bond formation. The aerogels had semi-crystalline structure, densities of 0.0009–0.003 g/mm³ and surface area of 2.4–7.6 m²/g. The LPC-pectin interactions can be explored to form tailor-made aerogels for bioactive delivery.