MODIFICATION OF SMECTITE STRUCTURE BY SULFURIC ACID ANDCHARACTERISTICS OF THE MODIFIED SMECTITE

Bentonite samples from Petrovac and Aleksinac were treated withsulfuric acid of different molarities. Differences in structure and texture of theinitial and modified bentonite were determined by chemical analysis and Xraypowderdiffraction (XRPD), infra-red spectroscopy (FTIR), scanning electronmicroscopy (SEM) and physisorption nitrogen at −196°C. Sulfuric acid caused anexchange of Al3+, Fe3+ and Mg2+ with H+ ions which led to a modification of thesmectite crystalline structure. The Mg and Fe substitution in the octahedral sheetpromoted the dispersion of those layers and forming of amorphous silicon. Thesequence according to which the cations left the octahedral sheets was as follows:Mg2+ Fe3+ Al3+. The sulfuric acid activated bentonites exhibiting a lower cationexchange capacity (CEC) and а change of specific surface area (SBET) from 6 to 387for bentonite from Petrovac and from 44 to 1784 m2 g-1 for bentonite fromAleksinac, positioning them as an excellent absorber in wine technology and in theprotection of soil and environment.