EFFECT OF MAGNETIC MODIFICATION ON THE SORPTION PROPERTIES OF NATURAL BENTONITE

Bentonite, due to its physical and chemical properties, is considered to be one of the most promising candidates for decontamination and disposal of high-level heavy metal wastes. Magnetic particles and their composites are also extremely suitable in water treatment. Therefore, the possibility to enhance the sorption properties of natural clay rock bentonite by its magnetic modification was investigated. The bentonite/iron oxide composites were prepared in different weight ratios at two selected temperatures 20 degrees C and 85 degrees C. The surface and pore changes of natural bentonite after magnetic modification was studied by nitrogen adsorption measurements. It was found that the composite prepared in weight ratio 1:1 of bentonite/iron oxide at 85 degrees C, denoted as A85, showed the highest increase in total pore volume (0.216 cm(3)/g) and the specific surface area from the value 39.4 m(2)/g of the natural bentonite to 82.8 m(2)/g of A85. The natural bentonite and composite materials were characterized by powder x-ray diffraction (XRD) analysis in order to quantify the structural changes. The magnetic properties were measured by superconducting quantum interference (SQUID) magnetometer and the morphology of the investigated samples was observed by scanning electron microscopy (SEM). The natural bentonite and composites A85 and E20 were chosen to study the sorption of cadmium from model solutions.