Annamária Mockovčiaková

Enhancement of the bentonite sorption properties

The almost monomineral fraction of bentonite rock-montmorillonite was modified by magnetic particles to enhance its sorption properties. The method of clay modification consists in the precipitation of magnetic nanoparticles, often used in preparing of ferrofluids, on the surface of clay. The influence of the synthesis temperature (20 and 85 degrees C) and the weight ratio of bentonite/iron oxides (1:1 and 5:1) on the composite materials properties were investigated. The obtained materials were characterized by the X-ray diffraction method and Mössbauer spectroscopy. Changes in the surface and pore properties of the magnetic composites were studied by the low nitrogen adsorption method and the electrokinetic measurements. The natural bentonite and magnetic composites were used in sorption experiments. The sorption of toxic metals (zinc, cadmium and nickel) from the model solutions was well described by the linearized Langmuir and Freundlich sorption model. The results show that the magnetic bentonite is better sorbent than the unmodified bentonite if the initial concentration of studied metals is very low.

Utilization of Ferromagnetic Fluids in Mineral Processing and Water Treatment

The paper is devoted to the utilization of ferrofluid as a separating medium and modifying agent affecting the magnetic properties of solid and liquid materials. The separation tests in a MHS separator have been carried out under laboratory condition. The selectivity of ferrofluids adsorption to the surface of some materials can be used for enhancing the magnetic susceptibility and influencing the efficiency of separation process. The enhancement of magnetic susceptibility of oil products up to a level sufficient for their magnetic extraction from water is possible by admixing of a definite amount of kerosene-based ferrofluid, which is non-miscible with water. The results point to the fact that the MHS method is suitable for the separation of non-magnetic materials according to their density and the modification of magnetic properties of materials by ferrofluid enhancing their magnetic separability.

Influence of ultrasound irradiation on cadmium cations adsorption by montmorillonite

AbstractThe objective of this work is study of the influence of ultrasound irradiation on adsorption properties of montmorillonite, contained in bentonite, mined in the Slovak deposit. First, structural properties of the adsorbent were characterized by Mossbauer spectroscopy, Fourier transform infrared spectroscopy and scanning electron microscopy. For the adsorption experiments, cadmium, as a heavy metal ion, was selected. The adsorption has been studied by a batch method using an ultrasound device and a rotary shaker. The montmorillonite adsorption properties have been tested under different conditions such as pH of the solution, initial metal ions concentration and temperature. It was observed that sonication markedly influenced the adsorption capacity of montmorillonite and its value increased by approximately 40% in comparison with the corresponding capacity of the non-sonicated material. No evident effect of temperature on the adsorption capacity of montmorillonite was proved.

In Situ Application of Bioleaching for Improving the Quality of Quartz Sand

Quartz sands contain various iron and clay minerals which coat silicate grains or are impregnated in silicate matrix. Treatment by basin water bioleaching in combination with electromagnetic separation can substantially improve the quality of quartz sands. The purpose of this in-situ study was to evaluate the feasibility of using a biological basin treatment process to improve the quality of quartz sands. The environmental conditions involved the changes of climate temperature, using fresh surface water without disinfection, inhibition of algae and fungi, and promoting bacteria. Analyses of the solution phase were used to monitor the dissolution of iron during the bioleaching of the quartz sands and to optimize the in-situ conditions for the bacterial activity. The rate of iron dissolution varied with environmental conditions, with the addition of nitriloacetic acid (NTA)/l and organic feedstock in the form of molasses. Bacterial removal of clay and iron minerals can be used to expose the white surfaces of quartz grains. The quartz sands from the Šaštín deposit (Slovakia) were used in glass industry after decreasing the Fe content.

Theoretical Model of Separation of Fine Particlesin a Rotating Ferrofluid

The application of centrifugal forces to a ferrofluid with finely grained particles located in a non—homogeneous magnetic field is the basis of the theoretical model of separation outlined in this paper. An analytical solution of the equation of the particle motion, its application under certain conditions, as well as the graphic representation of the results are presented.