Organic Dye Ozonation Catalyzed by Chemically Modified Montmorillonite K10-Role of Surface Basicity and Hydrophilic Character

Catalytic ozonation of organic dyestuffs such as Methylene-Blue (MB) and Malachite Green (MG) was investigated in the presence of montmorillonite K10 and its Al-Fe modified counterpart (AF-K10). Adsorption was found to play akey-role involving specific acid-base, electrostatic, and/or hydrophilic/organophilic interactions according to the dye molecule and catalyst surface properties. MG turned out to be more reactive toward ozone alone but showed lower reactivity for ozone than MB in the presence of catalyst. The higher degradation yields of MG obtained after only 40 s ozonation using 0.0166 g O-3 and AF-K10 can be explained by apossible clay-ozone synergy involving adsorption via both hydrophobic and additional acid-base interactions.