Preparation of TiO2-pillared montmorillonite as photocatalyst Part I. Microwave calcination, characterisation, and adsorption of a textile azo dye

Two photocatalysts based on TiO2-pillared intercalated montmorillonite have been prepared by microwave for 10 min at 700 W or by furnace heating at 673 K. Montmorillonite pillaring with TiO2 increased the basal spacing to 14.7 Å (conventional heating) and 17.6 Å (microwave heating). XRD patterns of both materials showed the presence of 100% anatase with a slightly higher rate of crystallinity obtained through microwave calcination than by conventional heating at 673 K. The BET specific surface area of the microwave prepared photocatalyst (151 m2 g− 1) was 3 fold higher than those of the Degussa TiO2 P25. At pH = 5.8, the maximum adsorption capacity of Solophenyl red 3BL (a textile azo dye) on the TiO2-pillared montmorillonite calcined by microwave was 185 mg g− 1, whereas it was 1.4 and 3 fold lower on the TiO2-pillared montmorillonite calcined at 673 K, and on the Degussa TiO2 P25 respectively. The influence of pH on the adsorption of the dye depended on the pHZPC of the pillared montmorillonites.