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Abstract

This work deals with sorption of cationic synthetic dye thioflavine T (ThT) onto the river sediment obtained from the Váh River under conditions of batch and column system using spectrophotometric methods. We found that sorption of ThT onto river sediment was a rapid process with reaching of concentration equilibrium within 2 h of interaction. The values of distribution coefficient (DC) defined as concentration ratio [ThT]sediment : [ThT]solution were linearly increased with increasing concentration of river sediment in solution within the range Csediment 1.25 - 10.0 g/dm3 and minimally changed in the range of initial pH values 2 - 6. The increasing concentration of ThT in model solution caused exponentially decrease in the value of DC. The sorption processes characterized by dependence between equilibrium specific sorption Qeq and ThT concentration Ceq in solution were better described by adsorption isotherm according to Freundlich (R2 = 0.979) than according to Langmuir adsorption isotherm (R2 = 0.914). From evaluation of ThT sorption onto river sediment in column system containing of 5 cm sediment layer with 30 cm of water column on the basis of ThT concentration changes in infiltrated water we found that these processes were significantly dependent on the rate of infiltrated water flow through the sediment layer Riw as well as on qualitative and quantitative composition of water. The highest ThT desorption from the sediment layer was found in seepage of 50 % (v/v) ethanol (EtOH) solution through the sediment and efficiency of ThT desorption decreased in the order: 50 % (v/v) EtOH > 0.1 mol/dm3 HCl > deionized water. Obtained data from the point of view of physico-chemical characteristics of the river sediment, such as pH, pHzpc (potentiometric titration), cation-exchange capacity (CEC) and elemental composition (X-ray fluorescence spectrometry), was also discussed

Abstract

The Heisenberg Hamiltonian appropriate to exchange clusters commutes with the square of the total spin ant its third component. Therefore in studying the exchange coupled clusters of medium/high nuclearity the spin quantum number S can be utilized in factoring of large interaction matrices (dimension of which is 104 - 105). Then the blocks of much lower size can be diagonalized using the desktop computers. To this end, the eigenvalues form the partition function Z(T,B) from which all thermodynamic properties, including the magnetization M(B,T0) and the magnetic susceptibility χ(T,B0), can be reconstructed. The matrix elements of the interaction operators in the coupled basis set of spin kets have been generated with the help of the irreducible tensor operators for a loop for S = Smin until S = Smax. In addition to the modelling of energy levels for different topologies, a fitting of magnetic data is exemplified by a number of examples like [Fe6] and [Mn3Cr4] systems

Abstract

A hydroponic study involving lettuce plants (Lactuca sativa L.) as a leafy vegetable was conducted to evaluate the 137Cs uptake and translocation in plant tissues in dependence on the presence or absence of K+ or/and NH4 + ions in cultivation media according to Hoagland (HM) during 8 d plants growth under hydroponic conditions. Significant increase of the 137Cs+ uptake by lettuce plants and the decrease of 137Cs+ translocation efficiency from roots to leaves were observed in 50 % HM deficient in K+ and NH4 + ions. Speciation analysis using Visual MINTEQ program showed that at micromolar concentration of CsCl (5 μmol/dm3) in 50 % HM at pH 6.0 and 25 °C, cesium was occurred practically only in the free cationic Cs+ form − 98.8 %, with minor proportions of other cesium species: CsCl − 0.4 %, CsNO3 − 0.4 %, and CsSO4 - − 0.4 %. Surplus of Cl-, NO3 - and SO4 2- ions in HM causes the increase of proportions of the cesium species CsCl, CsNO3 and CsSO4 -, respectively at the expense of bioavailable Cs+ form. Radiocesium 137Cs taken up via roots was removed from lettuce leaves with high efficiency by boiling in diluted NaCl solution. At ambient temperature the extraction of 137Cs with diluted acetic acid was concentration and time dependent process, and was succeeded by leakage of tissue components absorbing at 260 nm. These findings are important for the risk assessment of radiocesium entry into the food chain via contaminated leafy vegetable.

Abstract

The biosorption of Cu(II), Zn(II) and Ni(II) by microscopic green algae Chlorella kessleri was investigated using batch experiments. Biosorption studies with single and multi ion solutions were carried out to study the effect of several ions on the biosorption of selected metal. The influence of zinc and nickel on copper biosorption, copper and nickel on zinc biosorption and zinc and copper on nickel biosorption were investigated. The Langmuir and Freundlich model were used to describe the adsorption equilibrium of studied metals on Chlorella kessleri biomass. Based on the experimental results it was found that the presence of copper increased the biosorption capacity of zinc from 48.6 mg/g to 96.8 mg/g and nickel from 29.3 mg/g to 62.7 mg/g, respectively. However, the presence of nickel decreased the biosorption capacity of zinc from 48.6 mg/g to 31.7 mg/g.

Abstract

The acidic functional groups of the cell wall of native algae Parachlorella kessleri were evaluated by potentiometric titrations. The Gran´s method was applied to determination of the total, strong, weak and very weak acidities. The total organic acidity obtained for biomass was 3.93 mmol g-1, the largest content belonged to the strong acidic groups (2.13 mmol g-1) together with the weak acidic carboxylic groups (1.28 mmol g-1). Very weak acidities represented by the amine groups (0.52 mmol g-1) did not exceed 14% and they formed the lowest numerous part of all acidic functional groups.

Abstract

The evaluation of the toxicity and stress caused by heavy metals on plants is very important part of the phytoremediation research. Several physiological parameters can be used to assess the heavy metalinduced stress such as germination, plant growth and biomass production, photosynthetic pigments, antioxidant enzymes or antioxidants. Published results of measured physiological parameters in plants exposed to metals were characterized from of the negative effects of metals point of view and compared with the experimental study of the metal (Cu, Cd, Zn) toxicity in flax (Linum usitatissimum) and China aster (Callistephus chinensis) using the biochemical tests under the laboratory conditions. The germination and biomass production of C. chinensis significantly decreased with the increase of metal concentration which is considered a very typical response, however in L. usitatissimum slight stimulation of germination and biomass production at low metal content was observed. From the two studied plants C. chinensis expressed typical symptoms of the heavy metal toxicity including the decrease of total chlorophyll, chlorophylls a, b. On the contrary, heavy metal ions affected positively the physiological parameters of L. usitatissimum when low metal concentrations were added for example slight increase of the chlorophyll concentration in leaves was recorded. The decrease of the chlorophyll content was observed only at the high metal content. On the other hand, the typical response of plants on the heavy metal stress - the increase in peroxidase activity - was observed only for L. usitatissimum but not for C. chinensis that in all other tests showed significant toxicity symptoms. So if only one physiological parameter would be considered incorrect interpretation could be concluded. With the increase of phytoremediation practical applications the more systematic tests of heavy metal stress are necessary to help scientists working in that field correctly interpret their results and understand the plant behaviour.

Abstract

The paper deals with an application of bacterial leaching on two selected samples from old ecological loads situated in the Karlovy Vary Region. To be specific, they are heaps in Prebuz and Kraslice. Bacterial leaching was applied making use of Acidithiobacillus ferrooxidans bacteria and lasted 28 days. The results imply that the given method is suitable for the retrieval of valuable metals from waste and may help to deal with the issue of old heaps and dumps.

Abstract

In this paper, wheat straw and rapeseed residues before and after microwave pyrolysis during biooil production were studied as potential sorbents of heavy metals. The sorbents were characterized by elemental analysis and FTIR spectroscopy. Sorption properties of the materials were investigated using batch adsorption-equilibrium experiments and the effect of initial Cd and Pb concentration was studied. The experimental data fit Langmuir adsorption isotherm. The maximum sorption affinity of studied materials was observed in the case of rapeseed and its sorption capacity was 31.6 and 83.5 mg/g for Cd and Pb, respectively.

Abstract

The genesis of acid mine drainage (AMD) is conditioned by existence of indigenous chemolithotrophic iron and sulfur oxidizing bacteria, especially of genus Acidithiobacillus. The result of the oxidizing weathering of metal sulfides is a sequential formation of ochreous precipitates in drainage systems and in the surroundings of AMD seepage on the surface. The long-term monitoring of AMD waters collected at the shaft Pech that receives the majority of waters draining the flooded Smolník mine area point out the enduring contamination risk of particular components in the environment of Smolník mine area. Elemental analysis, X-ray diffraction, Mossbauer spectroscopy and scanning electron microscopy of the ochreous precipitates formed from Smolník AMD stream revealed schwertmannite as the dominant solid phase in the precipitates. The chemical analysis of AMD effluents and the elemental composition of related sediments indicated considerable scavenging potential of the ochreous precipitates towards metal cations and oxyanions of arsenic and sulfate

Abstract

Production of unsettleable sewage sludge with high water content is one of the problems of intensification of industrial activities and environmental protection. Sewage sludge with low toxic metals concentrations can be utilized as fertilizer and soil conditioner in agriculture. For determination of metal bioavailability, a wide range of extraction protocols and fractionation analyses can be used. We studied the distribution and quantified the leaching and bioavailability of zinc from dried anaerobic sludge by simultaneous, multi-step and three different sequential extraction protocols. For determination of zinc, the galvanostatic stripping chronopotentiometry (SCP) and electrothermal atomic absorption spectrometry (ETAAS) were used. The distribution of Zn in sequential extraction protocols was determined using a fivestep chemical fractionation procedures (BCR, Tessier and Van Hullebusch protocols). The potential bioavailability (0.9% NaCl, 0.1 mol/dm3 HCl, 0.1 mol/dm3 HNO3, 0.1 mol/dm3 CH3COOH, 0.1 mol/dm3 Na2EDTA, 0.1 mol/dm3 CaCl2, 0.1 mol/dm3 MgCl2, 0.1 mol/dm3 (NH4)2C2O4.H2O extraction) and pseudo total (aqua regia extraction and ETAAS analyses) content of Zn in sludge was determined. The amount of aqua regia extractable zinc in sludge samples was 650 ± 12 mg/kg (d.w.). We found out that the zinc was extractable from anaerobic sludge in first hour of contact time for all tested agents. Zinc was extracted with highest efficiency by 0.1 mol/dm3 (NH4)2C2O4.H2O, 0.1 mol/dm3 HCl and 0.1 mol/dm3 Na2EDTA. Sequential extraction protocols showed that the maximum extractable amount of zinc 126.3 ± 2.6 mg Zn / kg d.w. was bound to organic matter and sulfides. High concentrations of zinc in residual fractions were leachable under extraction conditions of strong acids only.