The main objective of the thesis was to evaluate the potential of selected Mn and Fe (nano)oxides for the stabilization of metals and metalloids in contaminated soils. The research was focused basically on three materials - commercial nanomaghemite (Fe III), nanomagnetite (Fe II,III) and a synthetic amorphous Mn oxide (AMO). The main aim of the work was to provide a complex view on the chosen stabilizing amendments regarding not just their direct influence on contaminants mobility and stabilization mechanisms, but also their stability and alterations in soil conditions together with influence on soil microorganisms and higher plants. Firstly, adsorption properties of the tested materials towards Cd, Cu, Pb and As were investigated. In this context, the most effective material showed to be the AMO reaching one to two orders of magnitude higher adsorption capacities than Fe III and Fe II,III under given experimental conditions. Interestingly, the rate of As(V) adsorption onto AMO was increasing with increasing pH as a result of high pHzpc of the AMO (8.1) and significant dissolution of this phase at lower pH values. As a next step, the influence of (nano)oxides on metal(loid)s mobility and other physico-chemical soil characteristics after application to contaminated soil was examined. Again, the AMO proved to be the most efficient in reducing mobile pools of Cd, Cu, Pb, Zn and As. On the other hand, Fe III and Fe II,III addition had generally less significant effects on contaminants mobility. AMO application further resulted in an increase of soil pH connected with AMO dissolution and unwanted decomposition of soil organic matter. When (nano)oxides alterations in soil conditions were observed, MnCO3 coatings were identified on AMO surface while no significant changes were recorded for Fe III and Fe II,III. As the MnCO3 formation was connected with increased AMO stability, AMO particles synthetically covered with MnCO3 coating (denoted as SM AMO) were prepared. Although the SM-AMO had a lower mass loss in soil than pure AMO, the stabilizing efficiency was almost the same for both materials. The differences in surface composition of both materials were decreasing with time as MnCO3 naturally precipitated on the AMO surface in soils while the SM AMO coating was gradually dissolving. When investigating the effect on soil microbiota, AMO efficiently promoted soil microbial activity while no significant changes were observed in the case of Fe III and Fe II,III. The AMO was also able to reduce the uptake of Cd, Pb and Zn by sunflower (Helianthus annuus L.), eliminate Zn phytotoxicity symptoms and increase biomass yield. On the other hand, toxic levels of Mn released from the AMO in an acidic soil were found in sunflower tissues. AMO application is thus recommended for contaminated neutral or slightly alkaline pH with a higher cation exchange capacity in order to avoid unwanted release of Mn. Finally, various types of AMO-biochar composite sorbents were recently prepared and field experiment focused on stabilization of Cd, Pb, Zn and As using studied materials is currently under preparation. The combined results from the thesis highlight the importance of a complex experimental approach dealing with all parts of the contaminated soil environment in order to obtain complete information about the efficiency and usefulness of any newly developed stabilizing amendment.

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The thesis deals with the influence of sorbents on the retention curve of the contaminated alluvial soil (fluvisol). The retention curves of soil without sorbents (reference soil) are compared with the soils enriched by the following sorbents. Biochar (BC), amorphous manganese oxide (AMO) and combination of (AMO + BC). Soils sample were collected is specific uncultivated area in the valley of Litavka river (located in the central part of the Czech republic). Two different types of samples were used for measurement of retention curves. First type of the samples were collected from the column experiments and second type were the samples collected in the field. All samples were extracted using in Kopecky rings (100 cm3). The measurement of the retention curves was performed by a direct method in the laboratory. For laboratory determination of the retention curves classical set of instruments were used (sandbox, sand-kaolin box and pressure apparatuses). The measured data were fitted using van Genuchten. Values compared are the bulk density, parameters of van Genuchten model (Thétas, ThétaR, Alfa, n), and values pF (0; 1.0; 2.0; 2.7; 3.0; 3.7; 4.18). The comparison of retention curves of differently treated soil was based on the average, standard deviation and the difference and ratio of the avarages. According to presented findings sorbents affected shapes of the retention curves. Especially biochar influence water content for high pF values. We confirmed the hypothesis according to VERHEIJEN et al. (2010), that biochar tincrase the total retention of soil water, but does not increase the amoust of water avaible plants. The influence of AMO on retention curve was negligible. Therefore sorbent AMO has a small influence on change of water retention in the tested soil. The effect of combined sorbent (AMO + BC) on the retention more significant than effect of using AMO sorbent only. This combination of sorbents affects the water retention depending on applied pF.

Amorphous manganese oxide has been already successfully tested as an efficient amendment for limiting the mobile fraction of risk elements in soil. However, its application is accompanied with an unsolicited phenomenon of increased dissolution of this agent related to oxidation of soil organic matter. For that reason, surface modification of the studied Mn oxide with the layer of MnCO3 has been proposed (Sm-AMO). The subject of this thesis is to assess the effectiveness of chemical stabilization of two contaminated soils using Sm-AMO with a focus on Zn and to verify the stability Sm-AMO based on laboratory experiments. The results of preliminary stability testing of both materials in demineralized water confirmed that Sm-AMO is less soluble than the original AMO. However, this fact was not confirmed by the results of testing of AMO and Sm-AMO performed using pH-static leaching experiments, when no differences were observed between AMO and Sm-AMO stability based statistical analysis, except for the natural pH (6.03) in the Litavka soil (soil L). Both sorbents yielded greater stability with increasing pH. Adsorption kinetics of Pb, Zn, Cd and As, which are present in the tested soils, onto AMO and Sm-AMO was studied to compare the adsorption properties of both materials. Affinity of these metals was generally higher towards AMO, but the recorded equilibrium time was similar for both sorbents. The results of adsorption kinetics for both materials tested showed the highest sorption rate and the highest adsorbed amount for Pb and the lowest for Zn. Similar results were also observed at pH-static leaching experiment. Stabilization effectiveness of Sm-AMO compared to AMO was mainly demonstrated for Pb and As under natural pH conditions (pH 6,03 and 6,43) of Litavka and Smolotely soils. Considering the stabilization of Zn statistically significant stabilizing effect of AMO/Sm-AMO was observed only at pH 8, when the AMO showed to be more effective. The effectiveness of Sm-AMO for the immobilization of Zn was not as significant as expected, but compared with other immobilization amendments Sm-AMO is an effective sorbent for Zn stabilization.

The subject of this graduation thesis is low-cost alkaline power cells and especially electrodes with alternative catalyst made of MnOx + dopant. The thesis expands the bachelor´s thesis [1] and previous research [4] [12] [13] [14]. Volt-ampere characteristics and power characteristics of the katodes for AFC, subsidized with various dopants, are the outcome of this project. The project presents the optimalisation of preparation process of AFC electrodes. The aim is to prepair several electrodes with identical construction, which varies only with the type of the dopant.

This thesis describes possibilities removal of iron and manganese from the water. The first part of the thesis describes the sources and forms of iron and manganese in water, the health limits and possibilities removal of iron and manganese from the water. Contact filtration and materials used for contact removing of iron and manganese are described in more detail. The second part describes using materials Birm, Greensand and Semidol in practise. There i also described the experimental removing of iron and manganese by these three materials.