Tatjána Juzsakova

Methodology development on aquatic environmental assessment

The Water Framework Directive aims at reaching the good ecological status of the surface and ground water bodies (László et al. Microchem J 85(1):65–71, 2007). The paper deals with quality evaluation of waters with special focus on the water chemistry parameters as defined in the Water Framework Directive and pertaining legal regulations. The purpose of this paper is to devise a quantitative type of water quality assessment method which could provide rapid, accurate, and reliable information on the quality of the surface waters by using water chemistry parameters. Quality classes have been defined for every water chemistry parameter in light of the legal limit values of the water parameters. In addition to this, weight indices were calculated on the basis of the outcome of the paired comparison of water chemistry parameters and normalized matrix. This was followed by the parametric level analysis of the water chemistry parameters, and finally, the aquatic environment index (AEI) was calculated, which provided general information on the quality of water regarding the water chemistry parameters. The method was illustrated on Lake Balaton, Hungary in which case water samples taken from Balatonfüred City lake area were analyzed and evaluated with the method devised.

Aquatic environmental assessment of Lake Balaton in the light of physical-chemical water parameters

One of the issues of the Hungarian Water Management Strategy is the improvement and upgrading of the water of Lake Balaton. The Water Framework Directive (WFD) specifies and sets forth the achievement of the good ecological status. However, the assessment of the water quality of the lake as a complex system requires a comprehensive monitoring and evaluation procedure. Measurements were carried out around the Lake Balaton at ten different locations/sites and 13 physical-chemical parameters were monitored at each measurement site.For the interpretation of the water chemistry parameters the Aquatic Environmental Assessment (AEA) method devised by authors was used for the water body of the Lake Balaton. The AEA method can be used for all types of the water bodies since it is flexible and using individual weighting procedure for the water chemistry parameters comprehensive information can be obtain. The AEA method was compared with existing EIA methods according to a predefined criterion system and proved to be the most suitable tool for evaluating the environmental impacts in our study.On the basis of the results it can be concluded that the status of the quality of studied area on the Lake Balaton can be categorized as proper quality (from the outcome of the ten measurement sites this conclusion was reached at seven sites).

Surface Characterization of Mechanochemically Modified Exfoliated Halloysite Nanoscrolls

Surface modifications fundamentally influence the morphology of kaolinite nanostructures as a function of crystallinity and the presence of contaminants. Besides morphology, the catalytic properties of 1:1-type exfoliated aluminosilicates are also influenced by the presence of defect sites that can be generated in a controlled manner by mechanochemical activation. In this work, we investigated exfoliated halloysite nanoparticles with a quasi-homogeneous, scroll-type secondary structure toward developing structural/functional relationships for composition, atomic structure, and morphology. The surface properties of thin-walled nanoscrolls were studied as a function of mechanochemical activation expressed by the duration of dry-grinding. The surface characterizations were carried out using N2, NH3, and CO2 adsorption measurements. The effects of grinding on the nanohalloysite structure were followed using thermoanalytical thermogravimetric/derivative thermogravimetric (TG/DTG) and infrared spectroscopic [Fourier transform infrared/attenuated total reflection (FTIR/ATR)] techniques. Grinding results in partial dehydroxylation with similar changes as those observed for heat treatment above 300 °C. Mechanochemical activation shows a decrease in the dehydroxylation mass loss and the DTG peak temperature, a decrease in the specific surface area and the number of mesopores, an increase in the surface acidity, blue shift of surface hydroxide bands, and a decrease in the intensity of FTIR/ATR bands as a function of the grinding time. The experimental observations were used to guide atomic-scale structural and energetic simulations using realistic molecular cluster models for a nanohalloysite particle. A full potential energy surface description was developed for the mechanochemical activation and/or heating toward nanometahalloysite formation that aids the interpretation of experimental results. The calculated differences upon dehydroxylation show a remarkable agreement with the mass loss values from DTG measurements.

NEW MESOPOROUS TITANIUM OXIDE-BASED PHOTOACTIVE MATERIALS FOR THE REMOVAL OF DYES FROM WASTEWATERS

The remarkable photocatalytic properties of titanium dioxide and the high adsorption capacity of the mesoporous materials were combined to obtain active photocatalysts for the decomposition of Rhodamine 6G dye. The mesoporous TiO2 was obtained by the controlled hydrolysis-condensation of titanium isopropoxide, using hexadecyl-trimethyl-ammonium bromide as template, followed by calcination to remove the organic matter. Subsequently, this sample was doped with sodium wolframate and platinum. The solids are highly porous, as proved by BET nitrogen adsorption. The photocatalytic tests were carried out at different dye concentrations, catalyst dose and pH. The experiments showed good activities for both the initial support and doped samples.