Aleksandra R. Zarubica

Significance of the structural properties of CaO catalyst in the production of biodiesel: An effect on the reduction of greenhouse gases emission

The influence of the physicochemical properties of a series of CaO catalysts activated at different temperatures on the biodiesel production was investigated. These catalysts show dissimilar yields in the transesterification of triglycerides with methanol. We have found significant relationships between structural properties (the type of the pore system, the typical CaO crystal phase and the sizes of crystallites (up to 25 nm), the minimal weight percentage of CaO phase, the total surface basicity and potential existence of two types of basic active sites) of CaO prepared and activated by means of thermal treatment at highest temperature and catalytic efficiency. Benefits of this catalyst are short contact time, standard operating temperature and atmospheric conditions, relatively low molar ratios and small catalyst loading. These all together resulted in a very high biodiesel yield of high purity. The properties of different biodiesel (obtained with the use of the prepared CaO catalyst) blends with different diesel and biodiesel ratios indicate that the higher the fraction of biodiesel fuel the better the achieved fuel properties according to the EU standards. A significant reduction of CO2 and CO emissions and only a negligible NOx increase occurred when blends with an increased biodiesel portion was used. The use of biodiesel derived blends, and the eventual complete replacement of fossil fuels with biodiesel as a renewable, alternative fuel for diesel engines, would greatly contribute to the reduction of greenhouse gases emissions. [Projekat Ministarstva nauke Republike Srbije, br. ON 172061 i TR 34008]

The correlation of metal content in medicinal plants and their water extracts

The quality of some medicinal plants and their water extracts from South East Serbia is determined on the basis of metal content using atomic absorption spectrometry. The two methods were used for the preparation of water extracts, to examine the impact of the preparation on the content of metals in them. Content of investigated metals in both water extracts is markedly lower then in medicinal plants, but were higher in water extract prepared by method (I), with exception of lead content. The coefficients of extraction for the observed metal can be represented in the following order: Zn > Mn > Pb > Cu > Fe. Correlation coefficients between the metal concentration in the extract and total metal content in plant material vary in the range from 0.6369 to 0.9956. This indicates need the plants to be collected and grown in the unpolluted area and to examine the metal content. The content of heavy metals in the investigated medicinal plants and their water extracts is below the maximum allowable values, so they are safe to use.

New Composite Materials in the Technology for Drinking Water Purification from Ionic and Colloidal Pollutants

© 2012 Ranđelovic et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. New Composite Materials in the Technology for Drinking Water Purification from Ionic and Colloidal Pollutants

Determination of Benzalkonium Chloride in Nasal Drops by High-Performance Liquid Chromatography

A high-performance liquid chromatography (HPLC) system was used in the reversed phase mode for the determination of benzalkonium chloride (BKC) in nosal drops. A Chromolit RP-18e, 100 x 4.6, (UM6077/035) column was used at 40 °C. The mobile phase, optimized through an experimental design, was a 70:30 (v/v) mixture of 0.057M Na-heksansulphonate potassium, dihydrogen orthophosphate buffer (pH 2.9) and acetonitrile, pumped at a flow rate of 1.75 mL/min at maintaining column temperature at 40 °C. Maximum UV detection was achieved at 215 nm. The method was validated in terms of selectivity, linearity, repeatability, precision and accuracy. The method was successfully applied for the determination of BKC in a pharmaceutical formulation of nasal drop solution without any interference from common excipients and drug substance. All the validation parameters were within the acceptance range, concordant to ICH guidelines.

The influence of selected process parameters on the reactions of n-hexane isomerization and transesterification catalyzed by sulfated zirconia

In view of the recent (ever) increasing need for environmentally friendly fuels, the processes of n-alkane isomerization and triglyceride(s) transesterification have gained importance because they enable the reduction of emissions of various hazardous substances into the environment. In this paper, sulfated ZrO2 as a heterogeneous acid catalyst was used in model reactions of isomerization of n-hexane and transesterification of sunflower oil. The goal of this research was to determine the optimal process parameters for isomerization and transesterification reactions, since they can have a large influence on both ecological and economical validity of these processes when used on the industrial scale. For the transesterification process, the parameters investigated were: the catalyst loading and methanol to oil molar ratio whereas in the isomerization reaction, the optimal process temperature was determined. The catalyst loading was proven to increase the yield of transesterification, but only until the mass percentage of the catalyst reaches 10%. The optimum methanol to oil molar ratio was shown to be 60:1, as further increase of the methanol amount decreases the transesterification yield. The temperature of 325 0C was determined to be optimal for the reaction of n-hexane isomerization under the experimental conditions applied.

Decolorisation of methylene blue over titania-based catalysts: The influence of different pH values used in the catalyst preparation procedure

In this study, nano-sized TiO2-based powders were synthesized by a modified solgel method. The influence of pH values of the precursor solution during the synthesis process on textural, structural and morphological properties of the titania-based catalysts was investigated. Photocatalytic activity of the prepared titania samples was tested by decolorisation/degradation of Methylene blue (MB) as a model pollutant under UV-A illumination. Finally, in order to optimize the photocatalytic process, the influence of the initial MB dye concentrations was also observed with the use of the catalyst sample synthesized at pH 10. The obtained results indicated a greater effect of the dye decolorisation when the catalyst prepared at pH 10 was used, compared with the catalyst prepared at pH 13. The photocatalytic activity was correlated with physico-chemical properties of the synthesized materials. .