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The powder mixtures of calcium oxide (CaO) and silica gel (SiO2) in molar ratios of 1:1, 1.5:1, 2:1 and 3:1 were mechanochemically treated with the addition of water, and were subsequently calcined with a goal of synthesizing CaSiO3, Ca3Si2O7, Ca2SiO4 compounds and CaO/Ca2SiO4 two-phase mixture. The prepared materials were characterized by XRD, FTIR, SEM/EDS, particle size laser diffraction (PSLD), UV-vis diffuse reflectance spectroscopy (DRS), N-2 adsorption/desorption isotherms, Hammett indicator for basic strength and volumetric analysis for free CaO content. The catalytic activity of calcium silicates with different Ca/Si ratios was tested in the transesterification of triacylglycerols (sunflower oil) with methanol. Samples obtained with initial composition 2CaO center dot SiO2 and 3CaO center dot SiO2 calcined at 700 degrees C, and 3CaO center dot SiO2 calcined at 900 degrees C had high catalytic activity, resulting with triacylglycerols conversion and fatty acids methyl ester formation (FAME or biodiesel) above 96%. The activity of these samples can be attributed to the existence of free CaO defined by CaO/Ca2SiO4 complex mixture. The effect of different amount of catalyst used for transesterification (0.2-2 wt%) was analyzed using the most active catalyst i.e. 3CaO center dot SiO2 calcined at 700 degrees C as well as possibility of its reuse for biodiesel synthesis. It was also found that CaSiO3, Ca3Si2O7 and Ca2SiO4, phases did not possess catalytic activity.

Supercritical CO2 (SC-CO2) extraction of fenugreek seeds (Trigonella foenum-graecum L, Fabaceae) was analyzed using different pressure and temperature (16.6-33.4 MPa and, 30-50 degrees C), which corresponded to SC-CO2 density between 779 and 957 kg/m(3). The yield of extract as well as its composition were determined and analyzed for different solvent consumption defined as mass of used CO2 for extraction per mass of dry fenugreek seeds. A central composite design (CCD) combined with response surface methodology (RSM) was used to study the best extraction conditions which determined that 27.0 MPa, 42.6 degrees C, and 24.6 gCO(2)/g(dm), were the optimal conditions for isolation of total extract. The calculated yield of extract at these conditions defined by SC-CO2 density of 890 kg/m3 could be 2.57% based on fenugreek seed. Moreover, the best extraction conditions for obtaining extract which contains the maximal amount of sterols, or maximal amount of vitamin E or vitamin D were also analyzed. These RSM optimizations showed that at slightly lower pressure (22.8-24.8 MPa), temperature (39.9-42.0 degrees C) and consumption of SC-CO2 (19.0-19.7 gCO(2)/g(dm)) is followed by smaller amount of isolated extract but with maximum content of sterols (16.28%), or vitamin E or vitamin D (1.44% and 0.71%, respectively) at these conditions. Calculation of molar solubility of total extract, and apparent solubility of sterols, vitamin E and D in SC-CO2 was performed at different pressure and temperature. They were correlated to density of SC-CO2, temperature at which extractions were performed and Hildebrand solubility parameter of solvent and solubility parameter of compounds which are the main constituents of extract. These calculations also show that the highest molar solubility of total extract and apparent molar solubility of its constituents could be obtained using optimal density of SC-CO2 (830-890 kg/m(3)) defined by corresponding values of temperature and pressure (310-320

A heterogeneous cerium-manganese oxide catalyst was synthesized by a co-precipitation method, characterized and tested in soybean oil transesterification with methanol under subcritical condition for methanol. Conversion of triglycerides after 40 min of transesterification in a batch process was over 99% with a fatty acid methyl ester (FAME) yield of 91.6% when 3 wt.% of catalyst based on oil, and 18:1 methanol/oil molar ratio were applied. The same amount of catalyst was used in 12 cycles of transesterification with catalyst regeneration performed only after the 7th cycle. The catalyst exhibited good tolerance toward soybean oil containing below 1.5 wt.% of water or 4 wt.% of free fatty acids. The mechanisms of Ce/Mn catalytic activity and its deactivation were discussed according to the characterization of the fresh and used catalyst according to results of different analytical methods: the Hammett titration, BET surface area, scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), FTIR, X-ray diffraction (XRD), ICP-MS and TG-DSC. It was assumed that deactivation of catalyst was mainly a consequence of manganese solubility in methanol and glycerol.

Pretreatment of fenugreek (Trigonella foenum-graecum L, Fabaceae) seeds was achieved using the step of defatting and acid hydrolysis. The obtained hydro-isolate (HI) was used as initial feed for diosgenin isolation by supercritical CO2 extraction (SC-CO2). Preliminary tests performed at conditions resulting in SC-CO2 density ranging from 800 to 920 kg/m(3) indicated that at some pressure, temperature as well as consumption of supercritical fluids the optimal working conditions for diosgenin isolation could be determined. For this purpose, the following range of working conditions of SC-CO2 were tested by using Central Composite Rotatable Design (CCRD) and Response Surface Methodology (RSM): pressure from 16.6 to 33.4 MPa, temperature from 30 to 50 degrees C and consumption of SC-CO2 from 11.6 to 28.4 g(co2)/g(dm). The result of this investigation indicated that maximum yield of 0.81 mg diosgenin from 1 g of fenugreek seeds on dry basis (about 1.3% of total extract) at 24.6 MPa, 43.5 degrees C, and 20.87 g(co2)/g(dm) could be obtained.

Calcium-containing perovskites CaTiO3, CaMnO3, CaZrO3 and Ca2Fe2O5 were synthesized by calcination of mechanochemically treated stoichiometric mixtures of CaCO3 and either TiO2, MnO2, ZrO2 or Fe2O3 powders. X-ray diffraction analysis revealed a pure single perovskite phase for all four samples after calcination. This study proved that the pure perovskite phase exhibited low or no catalytic activity at 60 degrees C for the methanolysis of sunflower oil. However, at 165 degrees C FAME yield of more than 90% was reached after 2 h using CaTiO3, CaMnO3 and CaZrO3 as catalyst. Contrary to inactive pure perovskites at 60 degrees C, the CaTiO3 and Ca2Fe2O5 samples containing a very small amount of "free" CaO also showed methanolysis activity at 60 degrees C. This fact can be used to explain some contradictory statements reported in literature related to the perovskites as catalyst for biodiesel synthesis at mild temperatures.

Supercritical CO2 extraction was studied using dried leaves of Mentha, originated from the northern part of Libya. Leaves were milled and sieved to obtain different average particles (d(p) = 0.25 - 0.80 mm). They were treated with supercritical CO2 at 313 K and 10 MPa in order to isolate essential oil. The new approach of supercritical extraction modelling on the basis of proposed "pseudo kinetic model" (PKM) was investigated and compared to most applied in literature Sovova's model. The main focus of these investigation was to determine the influence of particle size on extractions yield and to determine optimal methodology for determination parameters of PKM. Achieved results showed good agreement between both models and experimental results and good prospects for further usage of PKM.

A wide spectrum of phytochemicals could be isolated from sage (Salvia officinalis L) using different extraction or distillation technique: the supercritical fluid extraction (SFE), the volatiles compounds (monoterpenes and sesquiterpenes) isolation using hydrodistillation or higher molecular compounds with Soxhlet extraction or ultrasound-assisted extraction. The combination of ultrasound-assisted extraction followed by re-extraction of obtained extract with supercritical CO2 was performed in this study. The goal of performed investigation was to concentrate diterpenes present in sage extract which are generally considered to be responsible for antioxidant activity of extracted compounds. The fractionation using the supercritical CO2, and different combination of the ultrasound-assisted solvent extractions (water-ethanol mixture or only water) followed by supercritical CO2 re-extraction of obtained extract or treated plant material were analyzed and compared. Based on the results of these investigations it could be proposed the best extraction procedure: the ultrasound pretreatment of plant material with distilled water and re-extraction of plant material (residue) using supercritical CO2. That procedure gives two valuable products: the ultrasound extract which is rich in sugars and possess the immunomodulatory activity and supercritical extract which is rich in diterpenes and sesquiterpenes.

The supercritical carbon dioxide (SFE) extraction of Dalmatian sage (Salvia officinalis L) was investigated and compared to extraction performed by Soxhlet ethanol-water (70:30) mixture extraction (SE) and hydrodistillation (HD). The supercritical extraction allowed isolation of wide spectrum of phytochemicals, while other applied methods were limited to either volatiles (HD) or high molecular compounds isolation (SE). The kinetics of the supercritical extraction and fractionation within the pressure range of 10-30 MPa at 50 degrees C were also analyzed as well as the chemical compositions of total extract and partial or differential fractions isolated at different CO2. consumption. Volatile fraction could be isolated at low pressure and low CO2 consumption, whereby the pressures between 10 and 15 MPa followed by increased CO2 consumption were favourable for obtaining desired selectivity of diterpenes which contain compounds with expressed antioxidative characteristics.

Supercritical carbon dioxide extraction of sesquiterpenes from valerian root was investigated. Extractions from cultivar Arterner zuctung and two wild grown valerian subspecies were performed. The influence of extraction conditions on extraction yield and chemical composition of obtained extracts was investigated at temperatures from 40 degrees C to 50 degrees C and pressures from 10 MPa to 20 MPa. Chemical composition of obtained extracts was analyzed by GC/FID and GC/MS methods. The influence of particle size on extraction process was investigated at 40 degrees C and 10 MPa. The major constituents of supercritical extracts were valerianol, valerenal, bornyl acetate and kessanyl acetate. Optimal extraction conditions for the cyclopentanoid sesquiterepenes isolation, referred to the content of cyclopentanoid sesquiterpenes in extract, were found to be 50 degrees C and 15 MPa. Extract obtained from the cultivar was characterized by the higher content of cyclopentanoid sesquiterpenes, as well as valerenal comparing to extracts from wild grown species. At 40 degrees C and 20 MPa 19.6% of cyclopentanoid sequiterpenes isolated with methanol can be extracted. At 40 degrees C and 10 MPa, 17.4% of cyclopentanoid sequiterpenes isolated with methanol can be extracted. However, the extract obtained with methanol was characterized by the high content (42.51 %) of unwanted isovaleric as well as by the lower content of cyclopentanoid sequiterpenes than the extracts obtained with supercritical carbon dioxide. The process of supercritical extraction was influenced by particle size. In order to simulate the process, mathematical model on the secretory structure scale was derived. Results of the model showed good agreement with the experimental data.

Extraction with N-methyl-2-pyrrolidone (NMP) via the three-stage mixer-settler operation was studied as possible process for re-refining of waste mineral insulating oil. The following extraction process parameters were investigated systematically in order to determine their optimum values: amount of water as co-solvent in NMP, extraction temperature and solvent/oil ratio. The process parameters and resulting oil chemical compositions were found to influence the electrical properties and the oxidation stability of the re-refined oil. The levels of aromatic, paraffinic and polycyclic aromatic hydrocarbons were determined using IR spectroscopy and HPLC, while other relevant chemical and electrical properties of waste and re-refined oil were determined according to IEC, ISO and ASTM standards. Extraction using NMP was found to be an adequate method for waste mineral insulating oil re-refining, according to the application properties of the re-refined oil. Moderate extraction temperature, 1% water in NMP and a low solvent/oil ratio (0.5) were determined to be the optimum process parameters.