The binary system of vitamin K3 and CO2 was investigated at temperatures of 40 °C, 60 °C and 80 °C up to a pressure of 40 MPa. Solubility was measured by a static-analytic method. Partial molar volumes were determined by a method involving a vibrating tube densimeter. The solubility of vitamin K3 in CO2 is found as a function of pressure and temperature. The highest solubility was attained at a temperature of 40 °C. The partial molar volumes are negative and the dissolved vitamin K3 has a minor impact on the density of the solution of K3 in CO2 compared to the density of the pure CO2.
Highly macroporous polymers based on dicyclopentadiene (DCPD) have been successfully functionalized via a supercritical CO2 method aimed at minimizing the usage of organic solvents typically necessary for functionalization of polymers. The macroporous morphology of DCPD-based polyHIPEs resists the high pressures and the material exhibits an unusually high uptake of scCO2 at zero swelling. The scCO2 treatment creates additional mesoporosity, facilitating for the functionalisation within the void walls. The use of scCO2 as a solvent in the Prileschajew epoxidation and consecutive epoxide aminolysis of such epoxidized polydicyclopentadiene (pDCPD) monoliths is described. The procedure yields a high degree of functionalization with up to 6 mmol of β-amino alcohol derivatives per g of polymer.
In this study, we developed a novel high methoxyl pectin–xanthan aerogel coating on medical-grade stainless steel, prepared by ethanol-induced gelation and subsequent supercritical drying. Two non-steroidal anti-inflammatory drugs, i.e. diclofenac sodium and indomethacin, were incorporated into the aerogel coating. Electrochemical analyses were performed on the coated samples using electrochemical impedance spectroscopy and cyclic polarization techniques. The results showed that all passivated samples were highly resistant to general corrosion. The release of both non-steroidal anti-inflammatory drugs was complete after 24 h, as confirmed by the plateau in the drug release profiles as well as by IR spectroscopy after the final release point. The potential of samples for use in orthopedic applications was evaluated on a human bone-derived osteoblast cell and all samples were shown to be biocompatible. The increased viability of some samples indicates the high potential of the developed approach for future evaluation of possible clinical use.
A review of the solubility data for solids in sub- and supercritical fluids published in the literature between 2010 and 2017 is presented, including the pressure and temperature ranges and correlation methods. Compounds are categorized into the following groups: pharmaceutical, biological, aromatic, nonaromatic, organometallic, and polymer. The most commonly used solvent is supercritical CO2; some data have also been published for other solvents, such as argon, propane, and fluorinated hydrocarbons.
Hydrothermal conversion of biomass is a promising technology for the conversion of biomass into biofuels and biobased chemicals. This chapter is focused on the waste biomass conversion for production of biofuels and chemicals by applying sub- and supercritical fluids. One of the biggest disadvantages in biomass conversion by SCF is the extremely high energy requirement for heating the media above the water critical point (374 °C, 221 bar). The idea behind the recent research is to reduce the operating temperature and energy requirements by processing biomass with water at much higher pressures. The importance of knowledge on behavior of multicomponent systems at elevated pressures and temperatures is underlined. Methods, developed by the authors of this chapter for determination of thermodynamic and transport properties for multicomponent systems of different solid compounds and supercritical fluid under extreme conditions are described. Future perspective of hydrothermal technology as a tool to obtain advanced materials and the possible scope for future research is also discussed