Trajnostno procesiranje materialov z uporabo superkritičnih fluidov

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 extractionand 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.Superkritični fluidi (SCF) so močna topila s številnimi edinstvenimi lastnostmi. Imajo velik potencial za številne procese, kot so ekstrakcije, kemične reakcije in recikliranja. V skladu s tem so za načrtovanje procesa in študije ekonomske izvedljivosti potrebni podatki o faznem ravnotežju. Prav tako so poglavitne meritve termodinamskih in transportnih lastnosti v sistemih s superkritično fazo ter zanesljivi in vsestranski matematični modeli termodinamike faznega ravnotežja. Disertacija se osredotoča na prednosti tehnologije superkritičnih fluidov in je sestavljena iz treh glavnih delov. Prvi del vključuje študijo faznih ravnotežij binarnih plinsko-alkoholnih in plinsko-sečninskih derivatov. Raziskovali smo vpliv tlaka in temperature na obnašanje sistema (topnost, viskoznost, gostota, površinska napetost, krivulja tališča). Večina poskusov je bila izvedena z visokotlačno optično celico, z manjšimi modifikacijami aparature in merilnega principa za določitev omenjenih termodinamičnih in transportnih lastnosti. Drugi del doktorske disertacije obravnava pridobivanje ekstraktov iz naravnih materialov. Posebno zanimanje je usmerjeno v ekstrakte pridobljene s superkritičnimi fluidi, za katere so značilne različne biološke aktivnosti, predvsem protimikrobne in antioksidativne lastnosti. Superkritična ekstrakcija je bila izvedena na polkontinuirni aparaturi (pri tlakih 150 barov in 250 barov in temperaturah 313,15 K in 333,15 K za ekstrakcijo origanain pri tlakih 100 barov in 300 barov in temperaturah 313,15 K in 5 K3 za ekstrakcijo rdeče pese). Določitev protimikrobne in antioksidativne aktivnosti je bila izvedena z uporabo različnih metod, kot sta mikrodilucijska metoda in DPPH metoda. V tretjem delu je podan pregled različnih metod za recikliranje kompozitov, utrjeni z ogljikovimi vlakni, vključno s kemičnim recikliranjem s superkritičnimi fluidi. Izbrano področje je v svetu še vedno v fazi raziskovanja, saj je pristop relativno nov, a s trajnostnega vidika zelo zanimiv. Za ekonomsko izvedljivo načrtovanje procesa je potrebno določiti termodinamske podatke in podatke o prenosu mase. Načela prihodnjega laboratorijskega in pilotnega delovanja zahtevajo, da so ti podporni podatki znani. Rezultati, dobljeni v okviru te študije, predstavljajo visoko dodano vrednost na znanstvenem področju. Bistveni so za načrtovanje in spreminjanje procesov, ki dajejo izdelke, ki jih ni mogoče doseči s konvencionalnimi proizvodnimi procesi