The aim of this research was to investigate novel mesoporous materials, polysaccharide aerogels, as drug delivery carries in order to achieve controlled release of a model drug, diclofenac sodium. Pectin, alginate and composite pectin–alginate aerogels were prepared by cross-linking with three different ions, zinc, strontium and calcium. Calcium ions are not the best cross-linkers when controlled release is desired, since the release of a model drug was achieved in initial 1 h. Oppositely, zinc cross-linking provided more controlled release of diclofenac sodium. Therefore, zinc cross-linked pectin aerogels were used as the final drug delivery carriers in order to compare the release profile with two commercially available drugs. Pectin–zinc aerogel capsule degraded completely within the 24 h, oppositely both commercial drugs did not degrade even after 72 h. Moreover, the release profiles of all three tested drugs were dissimilar. Pectin–zinc aerogel capsule released 80% of the model drugs in 7 h, first commercial drug around 60% and second commercial drug nearly 100%.
Pyrolysis oils are a product of fast pyrolysis or liquefaction of biomass. Those dark brown organic liquids are chemically a complex mixture and/or emulsion of water and degradation products of lignin (e.g. guaiacols, catechols, syringols, vanillins), cellulose (such as levoglucosan, dehydrated sugars, di-sugars, furancarboxaldehydes), and hemicellulose (such as acetic acid, formic acid). Composition strongly depends on conditions of pyrolysis process and great variety of biomass feedstock such as grasses and trees, and other sources of ligno-cellulosic material, derived from municipal waste, food processing wastes, forestry wastes and pulp and paper by-products. The present contribution will present an overview of current high pressure processes for treatment of biomass for production of energy and chemicals as well as the fundamental studies of phase equilibria of the systems pyrolysis oil/gas, which are crucial in biorefinery process design. In particular, phase equilibria of binary and ternary systems consisting of pyrolysis oil/supercritical fluid (pyrolysis oil/CO2) and (pyrolysis oil/H2) was studied in addition to the phase behavior of ternary systems of (pyrolysis oil/diesel/CO2) and (pyrolysis oil/tail water/CO2). These data are important for design of separation processes as well as for the application of these substances for commercial fuels.
Esterification of n-butanol and D,L-lactic acid (D,L-LA), catalyzed by Candida antarctica lipase B (Novozym 435) in supercritical carbon dioxide (SC CO2)/ionic liquid (CYPHOS IL-201) medium and supercritical trifluoromethane (SC CHF3)/ionic liquid (CYPHOS IL-201) medium were studied. The experiments were successfully performed in a high-pressure batch stirred-tank reactor and were planned to elucidate the effect of CYPHOS IL-201 concentration, concentration of the enzyme, temperature and pressure on the efficiency of d,l-lactic acid and composition of D,L-LA. Concentration of CYPHOS IL-20,144%, 30 MPa, 55 °C and SC CHF3 were predicted to be optimal conditions for synthesis of n-butyl lactate: a maximum D,L-LA efficiency of 169% was attained. CYPHOS IL-201 showed to be a potential medium for the n-butyl lactate biosynthesis. In addition, the phase behavior for D,L-LA/n-butanol/Novozym 435/CYPHOS IL-201 system in SC CO2 at 65 °C and in SC CHF3 at 55 °C at different pressures were also carried out.
An overview of extraction methods is also given with supercritical fluid extraction highlighted as a promising eco-friendly alternative providing exceptional separation and protection from degradation of unstable polyphenols. The protective role of polyphenols against reactive oxygen and nitrogen species, UV light, plant pathogens, parasites and predators is taken under consideration. The protective and inhibitory action is derived from their high biological activity giving rise to prophylaxis or possibly even to a cure for several prevailing human diseases, especially various cancer types. The main problem represents their low bioavailability and rapid metabolism. One of the promising solutions lies in nanoformulation of polyphenols that prevents their degradation and thus enables significantly higher concentrations to reach the target cells.
The paper presents economically evaluated solutions for heating greenhouses with geothermal potential in two different locations in Southeastern Europe. The direct geothermal water exploitation using heat exchangers is presented and the remaining heat potential of already used geothermal water is exploited using high temperature heat pumps on NH3 or on supercritical CO2. Energy demands for heating greenhouses are calculated considering climatic parameters of both locations. Furthermore, different constructions materials are taken into account, and energy demands are evaluated. The results show that the geothermal energy usage is economically feasible in both locations, but for one location the direct heating is profitable, while for the other location the HTHP`s implementation is economically feasible.