Large amounts of coal combustion products (as solid products of thermal power plants) with different chemical and physical properties cause serious environmental problems. Even though coal fly ash is a coal combustion product, it has a wide range of applications (e.g., in construction, metallurgy, chemical production, reclamation etc.). One of its potential uses is in zeolitization to obtain a higher added value of the product. The aim of this paper is to produce a material with sufficient textural properties used, for example, for environmental purposes (an adsorbent) and/or storage material. In practice, the coal fly ash (No. 1 and No. 2) from Czech power plants was firstly characterized in detail (X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX), particle size measurement, and textural analysis), and then it was hydrothermally treated to synthetize zeolites. Different concentrations of NaOH, LiCl, Al₂O₃, and aqueous glass; different temperature effects (90–120 °C); and different process lengths (6–48 h) were studied. Furthermore, most of the experiments were supplemented with a crystallization phase that was run for 16 h at 50 °C. After qualitative product analysis (SEM-EDX, XRD, and textural analytics), quantitative XRD evaluation with an internal standard was used for zeolitization process evaluation. Sodalite (SOD), phillipsite (PHI), chabazite (CHA), faujasite-Na (FAU-Na), and faujasite-Ca (FAU-Ca) were obtained as the zeolite phases. The content of these zeolite phases ranged from 2.09 to 43.79%. The best conditions for the zeolite phase formation were as follows: 4 M NaOH, 4 mL 10% LiCl, liquid/solid ratio of 30:1, silica/alumina ratio change from 2:1 to 1:1, temperature of 120 °C, process time of 24 h, and a crystallization phase for 16 h at 50 °C.

Chelating agents, surfactants and many chemicals have been widely used for the extracting heavy metals from contaminated soil and sediment. The EDDS (S,S-ethylene-diamine-disuccinic acid), SDS (sodium dodecylsulfate) or Na4P2O7 (tetrasodium pyrophosphate) were studied as chemicals enhancing the metal extraction. However, by using of EDDS, metal exchange of extracted metal–EDDS and chemicals complexes with microorganisms and mineral cations may result in metal re-adsorption on the bacterial cells or soil and sediment particles. Therefore, this study deals with the investigation of presence of resistant bacteria in the soil and sediment with different Cu and Zn cations concentration, characterization of soil and sediment contamination, and with the biochemical releasing of Cu and Zn cations in the static flask experiments. Because of bacterial resistance, the bacterial growth on agar plate and medium with addition of 3 mM and 8 mM was retarded and the bacterial extraction of Cu and Zn cations from soil and sediment was lower than for the abiotic control especially with chemicals. Moreover, EDDS increased the Zn cations extraction from the soil and sediment and SDS increased the Cu cations extraction from the soil. The significance of Cu and Zn cations releasing was the decrease in the presence of heterotrophic resistant bacteria and not only in the presence of dissolved organic source. The higher adsorption of Cu cations than Zn onto cell surfaces during the biochemical leaching of soil and sediment samples is considerable.

The current work investigates the differences between four types of calcinated dolomite samples as suitable intermediates for subsequent silicothermic reduction of metal magnesium by simultaneous differential thermal analysis (DTA) /thermogravimetric analysis (TG). The results of the DTA/TG analysis showed the least significant differences at the temperature endotherms with no weight loss on the TG curves at a temperature of 1373 K for the calcined dolomite sample TR-1 from Trebejov deposit. The most significant difference on the DTA curves was detected for the calcinated sample KRA-1 (deposit Kraľovany), which is connected with the hydration activity of the sample. According to the results of the chemical analyses, annealing products of all samples fulfilled two of the three conditions, namely a molecular ratio of CaO:MgO and an impurity content below 2.5% for their subsequent use as feedstocks in the silicothermal process for the preparation of metallic magnesium. Subsequently, the experimental test of silicothermic reduction of magnesium of calcinated sample ST-1 in a flowing argon atmosphere was investigated by EDX analysis. The results indicate that the prepared magnesium sample analysed by EDX – point and mapping analysis confirmed the presence of magnesium totalling 91% despite the failure to reach the temperature in the furnace required for the reduction of Mg.

This study presents results of chemical leaching of contaminated soil from several metallurgically loaded locality of Richnava in Slovakia, applying two chelants – Na2EDTA and Na3EDDS of different molar concentration, done at different leaching conditions. The lower molar concentration (2 mM) of chelants showed comparable effect on Mn, Ni, As, Sb and Co leaching. Higher extraction was revealed at application of 10 mM chelants, especially for Cu and Cd release. Repeated washing of soil by 10 mM chelant without the media regeneration was more effective at the toxic elements removal than washing by smaller volumes of media or leaching of soil in static conditions. Final experiments focused on obtained leachates treatment showed that electrolysis and precipitation should represent a perspective way of the washing media regeneration.

Present scenario requires methods for treatment of industrially waste water polluted with hazardous chemicals and dyes. This work reports efficient utilization of nano-ceramic ‘hydroxyapatite’ for degradation of Indigo Carmine dye present in waste water under ultra violet light illumination. The photo-catalytic experiment is carried out via artificially polluting water with Indigo Carmine dye at three different dye concentration (5, 10, and 20 mg/L) in presence of hydroxyapatite nano-powder (25 mg). After 180 min ultra violet light illumination, almost 63, 61 and 43 % dye degradation is observed in above dye solution. Treatment of such dye polluted water is necessary for making it usable water for society and for the development of sustainable ecosystem.