We have investigated the transesterification of rapeseed and waste sunflower oils with methanol in the presence of catalyst. The effect of the temperature on the reaction rates was studied at a constant molar ratio alcohol:triacylglycerols and for a constant catalyst concentration. Size-exclusion chromatography and 1H NMR spectroscopy were used to quantitatively monitor the transesterification reaction. The mass-transfer coefficients of the triacylglycerols depended on the type of oil and temperature. Activation energies were calculated and the optimum methanol recycle ratio was established.
COBISS.SI-ID: 33677317
The microalga Chlorella vulgaris was cultured in a combined medium obtained bymixing standard Jaworski medium with a solution from the modified Solvay process that contained only NaHCO3 and NH4Cl. Cell number, pH and nitrogen content were monitored throughout growth. Lipids were extracted from lyophilised biomass using CHCl3-MeOH. A combination of grinding, microwave treatment and sonication proved to give the best lipid extract yield. Freeze-dried algal biomass was also utilised for thermal degradation studies. The degradation exhibited three distinct regions - primary cell structure breakage paralleled by evaporation of water, followed by two predominant exothermic degradation processes. The latter were modelled using nth order apparent kinetics. The activation energies of the degradation processes were determined to be 120-126 kJ/mol and 122-132 kJ/mol, respectively. The degradation model may be readily applied to an assortment of thermal algal processes, especially those relating to renewable energy.
COBISS.SI-ID: 35597317
In this work, the effect of polymer molecular weight and crosslinking reactions on the end-use properties of the microsphere water-based acrylic pressure-sensitive adhesives (PSA) is presented. Polymer molecular weight and polymer microstructure were regulated using different chain transfer agent (CTA) concentrations and by addition of a diacrylic monomer (MM). The adhesion properties of the synthesized PSAs were characterized via measurements of tack, peel adhesion and shear strength.
COBISS.SI-ID: 29587205
In the article we analyze technological possibilities in the Slovenian context as possible opportunities for promoting sustainable development based on regional, renewable resources. Beginning with an analysis of the amine process for CO2 concentration and its possibilities, we continue with CO2 chemistry examples, like the precipitation of calcium carbonate from Ca++ sources like lime or fly ash. Through the concept of product engineering we emphasize the need for a stepwise realization from the laboratory to a pilot plant and then to the industrial scale. The growth of biomass through forestry or algae production can provide an additional CO2 sink. However, for an efficient technical solution and implementation a close working relationship between biologists and engineers is required.
COBISS.SI-ID: 36189445
Probability of fire ignition as function of exposition to ignition sources and surface of the objects, two main process parameters with highest ponder, for a serie of studied examples is presented. Corellation is usefull fire for prediction of ignition probability under reasonable taking into account the relevant process parameters.
COBISS.SI-ID: 33808645