Bentonite Modification with Manganese Oxides and Its Characterization

The paper describes the preparation of new composite based on relatively cheap natural materials from domestic deposits and synthetically prepared manganese oxides. At first the natural bentonite was simple chemically modified by natrification. In general, bentonite is a rock with dominant presence of clay minerals from the smectite group, mainly montmorillonite. The properties of bentonite result from the crystal structure of this group. The particles of montmorillonite have negative charges on their faces due to isomorphic substitutions in structure. The natrification salt Na2CO3 is used almost exclusively thanks to its financial accessibility. The significant changes of surface properties after the modification of bentonite were observed. Natrification increased the surface area of bentonite. Then the manganese oxides were precipitated on the surface of activated sodium bentonite particles. The structural changes of bentonite, before and after its modification, were studied by X-ray diffraction analysis and FTIR spectroscopy. The morphology of the bentonites was observed by scanning electron microscopy. X-ray diffraction analysis demonstrated that the structural changes in the bentonite after natrification, the related exchange of Ca2+ cation for Na+ in the inter-layer space of the montmorillonite structure. Manganese oxide (MnO2) with regular birnessite layer structure was present in all of the bentonite samples of modified manganese.