SORPTION AND PHOTOCATALYTIC DEGRADATION OF AZOIC DYES ON TiO2-PILLARED MONTMORILLONITIC CLAY

This paper investigated the sorption and photodegradation processes of Congo Red on TiO2-pillared montmorillonitic clay and TiO2-pillared montmorillonitic clay modified by surfactant intercalation. The structural properties of the TiO2-pillared montmorillonitic clay and TiO2-pillared montmorillonitic clay modified by surfactant intercalation indicated an enlargement of the basal spacing of the clay. The enlargement was much pronounced as the used surfactant content increased. The Langmuir - Hinshelwood model was the base for interpreting kinetics data and working out of the rate constant and reaction order. The study determined the role of photocatalysis for the removal of Congo Red; under well determined working conditions, the efficiency of the process was double as compared to the simple sorption of the dye. In the studied experimental conditions a good correlation was observed between photocatalytic activity of the TiO2-pillared montmorillonitic clay and TiO2-pillared montmorillonitic clay modified by surfactant intercalation and both the specific surface area and the size of TiO2 crystallites values, affected by the modification route of Valea Chioarului clay.