Ivana I. Mladenović-Ranisavljević

Transformation of Synthetic Allicin: The Influence of Ultrasound, Microwaves, Different Solvents and Temperatures, and the Products Isolation

The transformation of the synthesized allicin, using conventional method, the influence of ultrasound and microwaves, in different organic solvents (acetonitrile, acetone, methanol, and chloroform), at various temperatures (room temperature, 45°C, and 55°C) was investigated. Allicin degradation kinetic was monitored by HPLC. Allicin transformation under the effect of microwaves is faster than transformations performed under the influence of ultrasound or by conventional method. Increase of the temperature accelerates allicin transformation. Pharmacologically active compounds of (E)-ajoene, (Z)-ajoene, 3-vinyl-4H-1,2-dithiin, 2-vinyl-4H-1,3-dithiin, and diallyl disulfide were isolated from the mixture of transformation products of allicin under the influence of microwaves in methanol at 55°C, which is according to kinetic parameters (highest values of the order of reaction and the lowest activation energy) the optimal method.

Evaluation of the Ecochemical Status of the Danube in Serbia in Terms of Water Quality Parameters

The Danube is an international river passing partly through Serbia. The protection of the environment and sustainable use of water resources is a primary task that implies constant monitoring of the quality status and evaluation of ecochemical status of the water in the Danube basin. The investigation includes calculation of all-inclusive water quality by the Serbian water quality index (SWQI) method and an evaluation of eco-chemical status of the Danube water in terms of water quality parameters from the entry to the exit point along its course through Serbia in the year of 2009. The results show that the overall quality of the Danube water on the territory of Serbia corresponds to the descriptive indicator of “very good” water. According to the Council Directive75/440/EEC, the evaluation of the ecostatus, with slight deviation of individual parameters at Pančevo, corresponds to A1 category of the surface water quality intended for the abstraction of drinking water supplies in member states.

Application of multivariate statistical techniques in the water quality assessment of Danube river, Serbia

Abstract The aim of this article is to evaluate the quality of the Danube River in its course through Serbia as well as to demonstrate the possibilities for using three statistical methods: Principal Component Analysis (PCA), Factor Analysis (FA) and Cluster Analysis (CA) in the surface water quality management. Given that the Danube is an important trans-boundary river, thorough water quality monitoring by sampling at different distances during shorter and longer periods of time is not only ecological, but also a political issue. Monitoring was carried out at monthly intervals from January to December 2011, at 17 sampling sites. The obtained data set was treated by multivariate techniques in order, firstly, to identify the similarities and differences between sampling periods and locations, secondly, to recognize variables that affect the temporal and spatial water quality changes and thirdly, to present the anthropogenic impact on water quality parameters.

Water Quality Assessment Based on Combined Multi-Criteria Decision-Making Method with Index Method

This work presents combined approach to water quality assessment based on both Water Quality Indices (WQI) and Multi-Criteria Decision-Making (MCDM) methods. Using weights from the official WQI calculation algorithm, the model for MCDM was formed and presented on the case of the Danube River water quality in Serbia. By applying PROMETHEE method, locations of potential environmental risk were determined and ranked according to the quality of water. Using its visual modeling option GAIA, the most dominant variables that affect the quality of water at certain locations were identified as polluting parameters (suspended matter, BOD-5, total N, NH4-N and PO4-P). Concentrations of identified pollutants were compared with limits of both EU and national recommendations so the actual water quality of the river was determined. The results showed that although WQI analysis indicated good and very good water quality, extension with MCDM methods revealed that there is a significant excess in values of PO4-P and E.coli at almost every location on the course of the river, as well as in values of total N and NH4-N. Proposed combined approach could serve to engineers and decision makers involved in water quality management in creating more detailed reports on water quality while facilitating the process of decision-making in the choice of selection of particular locations with critical water quality, where appropriate measures for remediation of pollution should be taken.