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Belgrade, Serbia

Rakic V.,University of Belgrade | Rac V.,University of Belgrade | Krmar M.,Institut Gosa | Otman O.,CNRS Research on Catalysis and Environment in Lyon | Auroux A.,CNRS Research on Catalysis and Environment in Lyon
Journal of Hazardous Materials | Year: 2015

In this study, the adsorption of pharmaceutically active compounds - salicylic acid, acetylsalicylic acid, atenolol and diclofenac-Na onto activated carbons has been studied. Three different commercial activated carbons, possessing ~650, 900 or 1500m2g-1 surface areas were used as solid adsorbents. These materials were fully characterized - their textural, surface features and points of zero charge have been determined.The adsorption was studied from aqueous solutions at 303K using batch adsorption experiments and titration microcalorimetry, which was employed in order to obtain the heats evolved as a result of adsorption. The maximal adsorption capacities of investigated solids for all target pharmaceuticals are in the range of 10-4molg-1. The obtained maximal retention capacities are correlated with the textural properties of applied activated carbon. The roles of acid/base features of activated carbons and of molecular structures of adsorbate molecules have been discussed. The obtained results enabled to estimate the possibility to use the activated carbons in the removal of pharmaceuticals by adsorption. © 2014 Elsevier B.V. Source

Jegdic B.V.,Institut Gosa | Bajat J.B.,University of Belgrade | Popic J.P.,University of Belgrade | Stevanovic S.I.,University of Belgrade | Miskovic-Stankovic V.B.,University of Belgrade
Corrosion Science | Year: 2011

The effect of different type of iron-phosphate coatings on corrosion stability and adhesion characteristic of top powder polyester coating on steel was investigated. Iron-phosphate coatings were deposited on steel in the novel phosphating bath with or without NaNO2 as an accelerator. The corrosion stability of the powder polyester coating was evaluated by electrochemical impedance spectroscopy (EIS), adhesion by pull-off and NMP test, while surface morphology of phosphate coatings were investigated by atomic force microscopy (AFM). The adhesion and corrosion stability of powder polyester coatings were improved with pretreatment based on iron-phosphate coating deposited from NaNO2-free bath. © 2011 Elsevier Ltd. Source

Holclajtner-Antunovic I.,University of Belgrade | Mioc U.B.,University of Belgrade | Todorovic M.,University of Belgrade | Jovanovic Z.,Vinca Institute of Nuclear Sciences | And 3 more authors.
Materials Research Bulletin | Year: 2010

Potassium salts of 12-tungstophosphoric acid with varying amounts of cation, KxH3 - xPW12O40 (x = 1, 2, 3) have been prepared and their characteristics investigated by thermal analyses, FT-IR and micro-Raman spectroscopy and SEM-EDS analysis. It was found that the number of replaced protons by potassium ions in the 12-tungstophosphoric acid structure has influence on the presence of different protonic species, their dynamic equilibrium and on the conductivity of salts. The results reported in this study have been applied to improve the structural model of insoluble acidic salts. It is shown that an acidic potassium salt presents a mixture of neutral salt and unreacted acid. The nature of this mixture depends on the number of replaced protons-oxonium ions by cations. Preliminary measurements with synthesized compounds as solid electrolytes in fuel cells have been done, too. © 2010 Elsevier Ltd. All rights reserved. Source

Popic J.P.,University of Belgrade | Jegdic B.V.,Institut Gosa | Bajat J.B.,University of Belgrade | Veljovic D.,University of Belgrade | And 2 more authors.
Applied Surface Science | Year: 2011

The influence of deposition temperature and concentration of NaNO 2 in the phosphating bath on the surface morphology and coverage of iron-phosphate coatings on low carbon steel was investigated. The phosphate coatings were chemically deposited on steel from phosphate bath at different temperatures (30-70 °C) and with the addition of different amounts of accelerator, NaNO2 (0.1, 0.5 and 1.0 g dm-3). The morphology of phosphate coatings was investigated using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The composition of iron-phosphate coatings was determined using energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). Surface coverage was evaluated by the voltammetric anodic dissolution (VAD) technique. It was shown that the increase in temperature of the NaNO2-free phosphating bath up to 70 °C caused an increase in surface coverage. The addition of NaNO2 in the phosphating bath significantly increased the surface coverage of phosphate coatings deposited at temperatures lower than 50 °C. The phosphate crystals were of laminated and needle-like structures for deposits obtained at temperatures lower than 50 °C, while at higher temperatures needle-like structure was transformed to laminated structure. The increase in NaNO 2 concentration in the phosphating bath from 0.1 to 1.0 g dm -3 did not significantly increase the surface coverage, but decreased the crystals size, consequently favouring the phosphate nucleation and better packing of the crystals. © 2011 Elsevier B.V. All rights reserved. Source

Kozic M.,VTI | Ristic S.,Institut Gosa
Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering | Year: 2010

Numerical simulations of two-dimensional (2D) flow obtained by solving the Reynolds-averaged Navier-Stokes (RANS) equations served for the design of 2D thrust vectoring nozzles. Thrust is directed by means of deflectors with different heights placed at the end of the bottom wall. The nozzle was manufactured and tested. A series of experiments were performed in a trisonic wind tunnel. The experimental results obtained by optical methods and pressure measurements are compared with the results of a numerical flow simulation. Differences were observed in pressure distribution along the bottom wall. More detailed research revealed that the real flow considerably deviated from the 2D flow. The primary goal of this work is to provide applicability of the used numerical methods in nozzle design. The results show that RANS 2D simulations with turbulent models based on the Boussinesq approximation are not able to predict reliable enough results for 2D thrust vectoring nozzles. Source

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