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1.
Determination of viscosity, density and interfacial tension of the carbon dioxide–isopropanol, argon–isopropanol, sulphur hexafluoride–isopropanol binary systems at 313.15 K and 333.15 K and at elevated pressures
Dragana Borjan, Maja Gračnar, Željko Knez, Maša Knez Marevci, 2022, izvirni znanstveni članek

Opis: Viscosity, density, and interfacial tension of three binary systems (carbon dioxide–isopropanol, argon–isopropanol, and sulphur hexafluoride–isopropanol) were measured at temperatures of 313.15 K and 333.15 K and at pressures up to 100 bar for carbon dioxide, and for argon and sulphur hexafluoride up to 500 bar. A vibrating tube densimeter method has been used for density measurements and a variable-volume high-pressure optical view cell with some modifications for the other measurements. The results showed that pressure does not have a high impact on viscosity. Density is found to be a linear function of pressure and temperature and the densities of the investigated binary systems increase with pressure and decrease with temperature. Interfacial tension decreased with the elevated pressure at a constant temperature for all the investigated systems. Accurate prediction of thermodynamic and mass transfer data is fundamental in various engineering and industrial operations to design processes with a higher yield of targeted compounds.
Ključne besede: viscosity, interfacial tension, carbon dioxide, argon, suplhur hexafluoride, isopropanol
Objavljeno v DKUM: 17.08.2023; Ogledov: 325; Prenosov: 36
.pdf Celotno besedilo (4,50 MB)
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2.
Sustainable processing of materials using supercritical fluids : doktorska disertacija
Dragana Borjan, 2022, doktorska disertacija

Opis: Supercritical fluids (SCFs) are powerful solvents with many unique properties. They have great potential for many processes, from extraction to chemical reactions and recycling. Accordingly, phase equilibrium data and thermodynamic and transport properties measurements in systems with a supercritical phase, as well as reliable and versatile mathematical models of the phase equilibrium thermodynamics, are needed for the process design and economic feasibility studies. The dissertation focuses on the benefits of supercritical fluid technology and consists of three main sections. The first section includes studies of the phase equilibria of the binary gas-alcohol and gas-urea derivatives. The influence of pressure and temperature on the system behaviour (solubility, viscosity, density, interfacial tension, melting point curve) was investigated. Most of the experiments were carried out with a high-pressure optical view cell, with minor modifications of the apparatus and measurement principle to determine mentioned thermodynamic and transport properties. The second part of the dissertation deals with the recovery of extracts from natural materials. Special interest is oriented towards supercritical fluid extracts, characterised by strong biological activities, especially antimicrobial and antioxidant properties. Supercritical fluid extraction has been performed on a semi-continuous apparatus (at pressures of 150 bar and 250 bar and temperatures of 313.15 K and 333.15 K for oregano extraction; and at pressures of 100 bar and 300 bar and temperatures of 313.15 K and 333.15 K for red beetroot extraction) and various methods such as the microdilution method and the DPPH method were used to determine antimicrobial and antioxidant activity. In the third part, an overview of different methods for recycling carbon fibre reinforced composites is given, including chemical recycling with supercritical fluids. This field has not been well explored, and the approach is relatively new but very interesting from a sustainable point of view. For an economically feasible process design, the thermodynamic and mass transfer data have to be determined. The principles of the future lab- and pilot-scale operations demand these supporting data be known. The results obtained in the frame of this study represent the high added value in the scientific field. They are essential to design and modify processes that yield products that cannot be achieved with conventional production processes.
Ključne besede: supercritical fluids, alcohols, urea, phase equilibria, viscosity, density, interfacial tension, modified capillary method, isolation methods, supercritical fluid extraction, pharmacological activity, carbon fiber reinforced composites, recycling techniques
Objavljeno v DKUM: 11.10.2022; Ogledov: 948; Prenosov: 133
.pdf Celotno besedilo (4,64 MB)

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