The first part of the dissertation is devoted to research of phase equilibria of triglycerides in sub and supercritical fluids. Data is key for further planning and formulation of high-pressure separation processes because they contributed to the improvement of certain industrial processes towards environmental protection and product quality. To determine the solubility of the glycerol tristearate-condensed gases and glycerol trioleate-condensed gases were used a high-pressure optical cell. The measurements were performed at different temperatures (30, 50, 70 and 90 ° C) and pressures up to 600 bar. The aim of our experimental work was to obtain information on the phase equilibria of glycerol and glycerol trioleate tristearate systems in supercritical CO2 and SF6, which are crucial for optimizing high-pressure separation and formulation processes. Data on the phase equilibria of glycerol tristearate-SF6 and SF6-glycerol trioleate in the literature is not. The data obtained are new and open up new prospects for the use of SF6 as a solvent for various media. For investigation of the influence of pressure to a temperature of the melting point and the determination of the melting heat of the various gas (nitrogen and CO2), we used high-pressure DSC. We have also determined the solubility and diffusion coefficient of the supercritical CO2 in a variety of natural polymers, which are used in the food industry as a binder, and in the various celluloses and starches. CO2 solubility in the polymer is dependent on temperature and pressure, as well as causing its swelling and thereby lowering the viscosity of the polymer. By increasing the solubility of CO2 in the polymer also increases the weight of the polymer. To determine the solubility of CO2 and diffusion, we used a magnetic suspension balance. The measurements were performed by means of magnetic suspension scales at different temperatures (40, 60, and 80 ° C) and pressures up to 300 bar. We determined high levels of solubility and diffusion coefficients of polymers when exposed to SC CO2. In any case, there was no dissolution of the polymer, but the polymer can absorb CO2 and swollen. From the obtained data it is clear that the solubility of CO2 in the polymers by increasing the pressure increases and decreases with increasing in temperature. Increasing pressure causes an increase in gas density and to improve the solubility, thereby increasing the volume of the polymer. By increasing the temperature is decreasing gas density. Diffusion coefficients of CO2 are dependent on the concentration of CO2 in the polymer. At the beginning, the value of the diffusion coefficient by increasing the solubility of the rise until the CO2 does not fill all free of voids in the polymer, and then apply these values to fall due to the action of hydrostatic pressure. By determining the solubility and diffusion coefficient of CO2 in polymers at a given temperature and pressure, we gain more information about the phase equilibrium polymer-gas, which are important for understanding and optimizing the process parameters. In the last part of the doctoral dissertation are bound natural yellow colorant curcumin from spices and 10% of the liquid extract on carriers such as triglycerides, polyethylene glycol, cyclodextrin, cellulose, and starches. We studied different combinations of colors and a mixture of various media with supercritical CO2. Micronized powder product dyes curcuma we measured the average size and the average size distribution of the resulting particles. We also supercritical and conventional extraction of turmeric (Curcuma longa L.). We have several different conventional extractions: extraction with cold solvent in a flask, Soxhlet extraction, ultrasonic extraction and extraction with conventional solvent at elevated pressures. The resulting extracts were analyzed antioxidant activity by means of using the free-radical methods. We are also in extracts determine the antioxidant value of the
D.09 Tutoring for postgraduate studentsCOBISS.SI-ID: 18195222
In recent years, polyethylenes (PE) are widely used for the advanced anticorrosion protection of various metal constructions and devices, which are very interesting due to their chemical and physical properties. Their use in varnishes and powder coatings industry becomes desirable and widespread since major limiting factor of environmentally hazardous volatile organic compounds % VOCs % plays a crucial role. Lately, trend in the world and especially in Europe is directed towards green chemistry to acquire products of high commercial value with minimum content of volatile organic compounds by processing and products manufacturing. Carbon dioxide (CO2) represents an excellent alternative to conventional solvents over many years. In the first part of dissertation the preliminary researches for low- and high density polyethelynes have been done to provide a good groundwork for high pressure processing. In a broad review of scientific papers and literature, data have not been found or their quality and/or quantity didn't reach minimum expectations. The main aim of the first part of research is acquirement of solid-liquid (S-L) phase equilibria for polyethylenes, solubility and diffusivity of gas (fluid) CO2 in polyethylenes. The data obtained are essential for polyethylenes processing. Behavior and ability of processing polyethylenes in sub- and supercritical fluids (CO2, propane) have been investigated. The solid-liquid (S-L) phase equilibria of low-density polyethelyne (LDPE) and high-density polyethelyne (HDPE) have been investigated in presence of carbon dioxide (CO2) and propane. Measurements of phase transition were performed in range of pressure of 1%90 MPa. Solubility and diffusivity of carbon dioxide in polyethylenes were measured at temperature of 373 K and pressures up to 30 MPa with using a magnetic suspension balance (MSB). The solubility of the fluid in polyethylene is influenced by pressure and/or temperature, and causes swelling of material. As well, mass of the polymer increases with solubility of gas. Consequently, viscosity and melting temperature of polymers reduce. In presence of carbon dioxide, the melting point of LDPE is influenced by two competing effects: a solubilization of gas in polymer and hydrostatic pressure. Oppositely, in presence of propane the hydrostatic pressure was not as pronnounced as in the presence of CO2. The solubilization effect of propane prevails over competing effect of hydrostatic pressure. For HDPE, in whole pressure range of CO2 the effect of hydrostatic pressure prevails, while in propane the solubilization effect prevails over competing effect of hydrostatic pressure. For the polyethylenes investigated in propane, melting point decreases in average for 17 K compared to CO2 medium. From MSB data it can be seen that solubility of CO2 in polyethylenes increases with increasing pressure. The highest solubility was obtained for low-density PE and the lowest solubility was obtained for high-pressure PE. In the second part of dissertation we focused on research of new technique of synthesis of biodegradable polymer of poly(propylene fumarate) (PPF) in supercritical carbon dioxide (scCO2). PPF could be used for biomedical applications and is potential as cellular ingrowth implant (substitute for human bone). PPF could be used as material for controlled (healing) substance delivery as well. Particularly, we were interested in an idea, whether the synthesis of PPF in absence of catalysts in scCO2 is possible. It has been found out the scCO2 is an excellent medium for the chemical synthesis of PPF.
F.09 Development of a new technological process or technologyCOBISS.SI-ID: 18722582
Invited lecture was presented at the Technical University Federico santa Maria, Chile. Nowadays supercritical fluids are able to replace conventional solvents, precisely because of their favorable properties. At the lecture several processess which are using supercritical fluids were presented: chemical and biochemical reactions, extraction processes, formultion of powder particles, the separation techniques (chromatography), the production of new materials and supports.
B.04 Guest lectureCOBISS.SI-ID: 18757398
A new technique for the synthesis of biodegradable polyester poly(propylene fumarate) (PPF), which is considered as one of potential materials for bone tissue engineering, has been developed. The new high-pressure synthesis in supercritical CO2 has been a number of advantages compared to conventional synthesis methods, i.e. a hiher reaction rate, higher purity of the obtained product, the synthesis is performed without a catalyst and an organic solvent. For the new, high-pressure process for synthesis of biodegradable polyester poly(propylene fumarate) (PPF) in supercritical CO2 a request for grant of a patent was submitted to the Slovenian office for intellectual propery.
F.33 Slovenian patentCOBISS.SI-ID: 18535702
A process for increasing purity of a low density polyethylene (LDPE) composition, comprising the steps of: a) providing a melted composition comprising LDPE having Mn of at least 5.0 kg/mol according to size exclusion chromatography, Mw of at least 50 kg/mol according to size exclusion chromatography, a density of 915 to 935 kg/m3 according to ISO1183 and a melt flow rate of 0.10 g/10 min to 80 g/10 min according to ISO1133:2011 measured at 190° C. and 2.16 kg, and b) providing particles from the melted composition by: b1) mixing a supercritical fluid in the melted composition to obtain a solution saturated with the supercritical fluid and b2) expanding the solution through an opening to obtain the particles.
F.09 Development of a new technological process or technologyCOBISS.SI-ID: 20094998