Papers by Author: V. Jovanović

Abstract: The surface properties of zeolites A, X, Y and natural zeolite clinoptilolite (CLI) functionalized by cationic surfactants were investigated. The quaternary ammonium type surfactants, such as hexadecyltrimethylammonium (HDTMA) chloride, stearildimethylbenzylammonium (SDMBA) chloride and distearildimethylammonium (DSDMA) chloride, replaced inorganic cations like Na+ and Ca2+ on the external surface of zeolites. The adsorption capacities of all organic cations followed the order of CLI>CaY>CaX>CaA>NaY>NaX>NaA and increased with the increase of Si/Al molar ratio in zeolite structure. This modification resulted in an alteration in the surface property of zeolites - it changed from hydrophilic to hydrophobic. The adsorption of selected pesticides with different hydrophobicity on surfactant-modified zeolites was studied. It is shown that surfactant-modified zeolites can be used for removal of pesticides from the environment. The increase in hydrophobicity of pesticides resulted in an increase in pesticide adsorption on SDMBA and DSDMA modified zeolites.

Abstract: The methanol oxidation was studied at two differently prepared supported Pt electrodes (Pt-C/GC and Pt/GC) in 0.5 M H2SO4 and 0.1 M NaOH. The supported Pt electrodes were characterized by AFM, STM TEM and HRTEM. The higher activity of Pt-C/GC than of Pt/GC catalyst, as well as negligible differences in the activities between the supported Pt catalysts and the corresponding single crystal electrodes oriented as the sites in the catalyst deposits in which Pt particles are dominant, clearly suggest the influence of the particle size effect on the catalyst activity.