Srđan Petrović

Photocatalytic degradation of azo pyridone dye: Optimization using response surface methodology

Abstract Response surface methodology (RSM) and central composite design have been applied to describe and optimize photocatalytic degradation of azo pyridone dye using TiO2, H2O2, and simulated sun light. The mutual interactions between three independent variables, viz. H2O2 concentration, irradiation time, and TiO2 content were obtained. The results revealed that the most influential variables under selected reaction conditions were irradiation time and TiO2 content. The optimized conditions for the photocatalytic degradation of azo pyridone dye were as follows: H2O2 concentration: 130.5 mg/L, irradiation time: 54.8 min, and TiO2 content: 2.48 g/L. Under these conditions, the maximum decolorization efficiency of 96.43% was achieved. This experimental value was in good agreement with the predicted one, which proved the validity of the model. Operation cost analysis indicated that irradiation time had the major influence on total process cost. The RSM based on the central composite design was shown to be ...

Mechanochemical Activation in Synthesis of LaTi0.5Mg0.5O3 Perovskite-Type Oxides

Perovskite-type oxide of LaTi0.5Mg0.5O3 composition was synthesized from constituent oxide precursors by mechanochemical activation method in a high power planetary ball-mill, followed by thermal treatment of the product in air. The phase composition after mechanochemical activation of the binary and ternary mixtures was studied by XRPD, while the surface state of the constituent elements was characterized by XPS. The phase composition and surface properties of binary and ternary mixtures obtained by mechanochemical treatment show an affinity of the constituent oxides for the formation of perovskite-type compounds. Using thermally stable phase LaTi0.5Mg0.5O3 (perovskite-type) obtained by the applied procedure, a total oxidation of metane at 750 800 °C was achieved.

Study of the effect of Mg(II) addition and the annealing conditions on the structure of mesoporous aluminum oxide using Plackett–Burman design

A statistical design was used to investigate the effect of various pro- cessing conditions on the structure of sol-gel derived Mg(II) doped alumina. Six process variables were selected based on the Plackett-Burman design: concentration of magnesium nitrate, time and temperature of alcohol evapor- ation, temperature and time of annealing and heating rate were changed at two levels. For every set of conditions, samples with different specific surface area and degree of crystallinity were obtained. Analysis of the results showed that the annealing temperature, heating rate and concentration of magnesium nitrate were the main factors affecting the average crystallite size of the predominant alumina phase. In the case of the specific surface area, two of selected six variables had pronounced effects; however, the temperature of annealing was more effective than others. The present results showed that the proposed model that uses crystallite size as a response variable is preferable to other research.

Size-segregated trace elements in continental suburban aerosols: seasonal variation and estimation of local, regional, and remote emission sources

We have measured trace element contents in suburban aerosols from six size fractions in the range of PM0.27–16 from a background station in Belgrade (Serbia). The distribution and concentration of elements were determined within each of the investigated Dp fractions with emphasis on the fine and coarse modes. Fine/coarse mode ratios of element can provide information regarding their anthropogenic or natural origin. Analysis of seasonal variations of element contents in fine and coarse mode show that Cd, Co, K, and V have higher concentrations in the fine mode during heating season, while Fe contents are lower. In the coarse mode, Cu and V have higher concentrations during the heating season, while Al, Fe, Mg, Mn, and Sb contents are lower. We also apply a distribution probability model (normal, log-normal, and three-parameter Weibull) as new approach to estimate the distances of emission sources that can contribute to pollutant contents in particulate matter of the investigated location.