Mirjana Vojinovic-Miloradov

Catalytic Preparation and Characterization of C60Br24

Abstract In this paper the procedure for catalytical bromination of C60 with elementary bromine with FeBr3 as a catalyst is described. In this procedures only one reaction product - C60 Br24 is obtained. The twenty four bromine atoms are symmetrically distributed over the C60 sphere, which was confirmed by thermogravimetric analysis. The yield of bromine derivative in this reaction is 98%.

Antioxidant profile of Trifolium pratense L.

In order to examine the antioxidant properties of five different extracts of Trifolium pratense L. (Leguminosae) leaves, various assays which measure free radical scavenging ability were carried out: 1,1-diphenyl-2-picrylhydrazyl, hydroxyl, superoxide anion and nitric oxide radical scavenger capacity tests and lipid peroxidation assay. In all of the tests, only the H2O and (to some extent) the EtOAc extracts showed a potent antioxidant effect compared with BHT and BHA, well-known synthetic antioxidants. In addition, in vivo experiments were conducted with antioxidant systems (activities of GSHPx, GSHR, Px, CAT, XOD, GSH content and intensity of LPx) in liver homogenate and blood of mice after their treatment with extracts of T. pratense leaves, or in combination with CCl4. Besides, in the extracts examined the total phenolic and flavonoid amounts were also determined, together with presence of the selected flavonoids: quercetin, luteolin, apigenin, naringenin and kaempferol, which were studied using a HPLC-DAD technique. HPLC-DAD analysis showed a noticeable content of natural products according to which the examined Trifolium pratense species could well be regarded as a promising new source of bioactive natural compounds, which can be used both as a food supplement and a remedy.

Water quality of Yugoslav rivers (1991–1995)

Abstract Yugoslavias exposure to UN sanctions since 1992 resulted in a production reduction in almost every field of economic activity, and that caused a decrease of pollutant inputs in the water ecosystems. Although the boundary profiles of international rivers registered no change, an improvement was detected in river water quality on profiles that run deeper inside the country. The quality of Yugoslav rivers in period from 1991 to 1995 is presented in this paper. The quality of the Danube, Tisa, Sava, Drina, Morava, Ibar, Bojana and Moraca is evaluated by the concentrations of characteristic parameters. The specific situation where the reduction in industrial and agricultural production occurred, together with reduced traffic activities and uncontrolled black-market import of fertilizers, influence the changes in concentrations of water quality parameters. It is possible to conclude, based on analysed data, that a general improvement in the quality of Yugoslav rivers has occurred during the period of observation, 1991–1995.

Seasonal variations of bisphenol A in the Danube River by the municipality of Novi Sad, Serbia

Seasonal variations of bisphenol A (BPA) were investigated in the Danube along the Novi Sad bank, Serbia using solid-phase extraction followed by gas chromatographic mass spectrometric method. The obtained results confirmed the presence of BPA above the limit of quantification (6 ng/L) in 22 out of 32 water samples at all eight sampling sites. Тhe BPA concentration varied from 1) for autumn, spring and summer. The high potential risk which is attributed to the elevated summer concentrations is probably the result of the increased human activates and weather conditions.

Fuzzy model for determination and assessment of groundwater quality in the city of Zrenjanin, Serbia

The application of the fuzzy logic for determination and assessment of the chemical quality of groundwater for drinking purposes in the city of Zrenjanin is presented in this paper. The degree of certainty and uncertainties is one of the problems in the most commonly used methods for assessing the water quality. Fuzzy logic can successfully handle these problems. Evaluation of fuzzy model was carried out on the samples from two representative wells that are located at depths of two aquifers from which water is taken to supply the population with drinking water. The samples were analyzed at 8 different chemical water quality parameters. In the research, the arsenic concentration (As 3+ and As 5+ ) is considered as the dominant parameter due to its suspecting carcinogenic effects on human health. This type of research is for the first time conducted in the city of Zrenjanin, middle Banat region.

Effect of extremely high specific flow rates on the removal of NOM and arsenic from groundwater with an ion-exchange resin: A pilot-scale study in Northern Serbia

A pilot-scale study was performed to explore the possibility of the removal of natural organic matter (NOM) and arsenic from groundwater in the village of Melenci (Northern Serbia) using strongly basic, macroporous ion-exchange resin, commercially available as Amberlite IRA 958-Cl. The influences of the specific flow rate (SFR) and a broad range of contact times were studied using native groundwater and the same water pretreated with sodium hypochlorite (NaClO) for the oxidation of As(III) to As(V) and the degradation of NOM. The investigated SFR exceeded the manufacturers recommended maximum value by up to ten times. In the range of SFR from 50 to 300 bed volumes per hour (BV/h), a higher efficiency of NOM removal was achieved in the absence of the oxidant, whereas at lower SFR and shorter contact times, the efficiency was higher when the water was pretreated. The arsenic removal from the oxidant-pretreated water was equally efficient at all SFR, whereas in the absence of the oxidant the efficiency was significantly lower and did not depend on SFR. The effectiveness of the resin illustrates the fact that the experimentally determined optimum SFR value of 30 BV/h is stated as the maximum in the manufacturers specifications.

COVALENT AND NON-COVALENT DERIVATIVES OF FULLERENE C 6 11 AND ITS BIOLOGICAL ACTIVITY

This paper presents the basic chemical characteristics of buckminsterfullerene-molecule CM60 and some of its biologically active derivatives. This new form of carbon with unique properties, discovered in 1985, is a very reactive species undergoing a variety of chemical reactions leading to a wide spectrum of possible covalent derivatives. Besides covalent compounds, fullerene reacts with different dopants to form non-covalent complexes, including endohedral, exohedral systems (intercalates). The review of the most significant papers on noncovalent and covalent derivatives and their biological activity is given, as well as our results in this field. Formation of intercalates of fullerene with small molecules of aliphatic alcohols is described and the importance of topology and size of dopants and the role of solvents in formation of intercalates is explained. Original synthesis of bromine derivative C60Br24 and water-soluble polyhydroxy derivative C60(OH)24 is described. Antioxidative effects of the latter compound were investigated in chemical model system and in vitro system of human neoplasmatic cells. The paper also gives theoretical explanation of addition C60R24 derivatives together with assumption about antioxidative activity of fullerol. .

Residual Toluene Concentrations in Exhaust Gas Waste Stream of Motor Vehicle

Vehicles are the dominant source of many air pollutant emissions in urban areas. The effects caused by vehicle emissions have been receiving increasing attention, and recent epidemiological studies show elevated risks of cardiovascular morbidity, cancer, allergic diseases for drivers, commuters and individuals living near roadways. During the experimental research conducted in this paper, emission characteristics of Otto 1.1 EFI engine were investigated in varying operating modes in order to adequately simulate the movement of the Fiat Punto Classic (FPC) passenger car in city driving conditions in line with the New European Driving Cycle (NEDC). The NEDC is a stylized cycle, with periods of constant acceleration, deceleration and constant speed, and it is supposed to represent the typical usage of a passenger car in Europe. The analysis of exhaust gas samples was conducted by using the gas chromatography technique in combination with the photoionization detector (GC/PID). The results of emission tests indicate high concentration levels of toluene in the exhaust gas mixtures, ranging from 7.07 to 116.87 ppm. The total mass of the emitted toluene after 100 km of driving in accordance with the NEDC was 7.7647 g.

BTEX in the Exhaust Emissions of Motor Vehicles

Transportation involves the combustion of fossil fuels to produce energy translated into motion. Pollution is created from incomplete carbon reactions, unburned hydrocarbons, or other elements present in the fuel or the air during combustion. These processes produce pollutants of various species, including carbon monoxide, soot, various gaseous and liquid vapour hydrocarbons, oxides of sulphur and nitrogen, sulphate and nitrate particulates, and ash and lead. These primary pollutants can, in turn, react in the atmosphere to form ozone, secondary particulates, and other damaging secondary pollutants. Benzene, toluene ethylbenzene, and xylenes, known collectively as the BTEX group, are an important fraction of non-methane hydrocarbons and have been found to be ubiquitous in the urban air. BTEX are known to be toxic and genotoxic and they also actively participate in the photochemical reactions. This chapter presents the results of research in the field of BTEX concentration in the exhaust gases of spark ignition engines under different operating conditions. The aim of this chapter is to obtain a clearer insight into the impact of different engine working parameters on the concentration of BTEX gases. Exhausts have been sampled directly at the tail pipe. Detection and quantification of BTEX concentration levels have been performed by using mobile GC Voyager Photovac equipped with capillary column Supelcowax 10 and photoionisation detector. The results indicate high concentration levels of target compounds, especially in conditions of incomplete combustion simulated by creating hydrocarbon–air-rich mixtures, low engine load, and low revolutions per minute of the experimental motor.

Environmental Pollution by Organic Contaminants as the Contributors of the Global Warming

Because they contain black carbon as the UV-absorbing component, soot particles are regarded as contributing significantly to global warming. They are released to ambient air during the burning of solid, liquid, and gaseous fuels—coal and petroleum in particular. Concurrently with soot, polycyclic aromatic hydrocarbons (PAHs) are formed as the by-products of the incomplete combustion of organic matter. A correlation between concentration levels of PAHs in atmospheric particles and soot content is detected, given PAHs’ high affinity for carbonaceous materials and strong sorption to soot particles. Therefore, it can be assumed that sorption to the soot particles governs the gas–particle partition process of polycyclic aromatic hydrocarbons in ambient air. The main objective of the chapter is to estimate the gas–particle partition of PAHs using the soot–air partition coefficient (KSA) within the model proposed by Dachs–Eisenreich and to compare the modeled values with results obtained from the field measurements. Air sampling campaign is performed during the early summer period at six selected urban and industrial localities in Vojvodina (Serbia), using the high-volume ambient air samplers. For each sampling period, one quartz fiber filter (GF) and two polyurethane foam filters are used. Contemporary usage of both types of sampling medium has enabled the simultaneous collection of suspended particles and gaseous phase of PAHs. Samples are analyzed using GC-MS instrument (HP 6890–HP 5972) supplied with a J&W Scientific fused silica column DB-5MS. The statistical analysis is performed using Statistica 10. The modeled values obtained using the Dachs–Eisenreich approach are in reasonable agreement with results from the field measurement and, consequently, confirm that soot–air partition coefficient can be used as prediction parameter of the gas–particle partitioning processes for PAHs.