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Emília Kubiňáková, Ján Híveš and Vladimír Danielik

Abstract

Electrical conductivity of NaF-AlF3 melts with an addition of 2 wt % Al2O3 and/or 5 wt % CaF2 was measured using a pyrolytic boron nitride tube-type cell with a constant distance of electrodes. The molar cryolite ratios MR = n(NaF)/n(AlF3) were 1.8 and 1.6, and the temperature was varied from 865 °C to 1005 °C. Ac-techniques with a sine wave signal with small amplitude in the high frequency range were applied. Electrolyte resistance was obtained from nonlinear regression analysis according to equivalent circuit. Experimental data were used to describe the dependence of the electrical conductivity in fluoride melts with lower temperature on the amount of various additions and temperature.

Open access

Katarína Gazdová, Emília Kubiňáková, Ján Híveš and Tomáš Mackuľak

Abstract

In recent years, interest in the presence of chemical and biological pollutants (drugs, pesticides, heavy metals etc.) in sewage water has been permanently increasing and, at the same time, significant effort to eliminate them has been shown. The aim of this work was to investigate the influence of ferrates activity on the decomposition of the drug diclofenac (DCF), which is commonly present in sewage water. The main task is to follow the effect of potassium ferrate dosage on DCF degradation and to evaluate the most effective ferrates concentration in solution. Subsequently, real samples of waste water containing a significant amount of various micro‑pollutants were treated by the same amount of ferrates as laboratory samples. High-performance liquid chromatography (HPLC) was used for the sample analysis. Ferrates removal effectiveness was determined by comparing the chromatographic peak areas of residual DCF in the treated samples. Removal efficiency of diclofenac is proportional to the concentration of potassium ferrate in the treated solutions.

Open access

Kamil Kerekeš, Katarína Švaňová, Ján Híveš and Miroslav Gál

Abstract

During last decades interest in ferrates(VI) has increased significantly. On one hand they serve as strong, non-toxic oxidants without harmful by-products and, on the other hand, as an efficient coagulant in both drinking and waste water treatment technology. In this work we focused on the electrochemical preparation of ferrate (VI) salts in eutectic low temperature molten sodium hydroxide - water mixture using pure iron anodes. Some information on the stability and kinetics of decomposition of sodium ferrate(VI) prepared by molten-system electrolysis is discussed. An assumption that electrochemically prepared ferrate(VI) in molten hydroxide media are stable enough to be used especially in the field of waste water treatment was confirmed by our observation.