Photoactive TiO2-montmorillonite composite for degradation of organic dyes in water

TiO2–montmorillonite composite (TiO2–M) was prepared by impregnation with TiCl4 followed by calcination at 350 C. The synthesized material was characterized by FTIR, TG–DTA, BET, XRD and SEM– EDX. The results show that TiO2 was efficiently formed in Na–montmorillonite (Na–M) framework, and only a crystalline, pure anatase phase was produced. Photoactivity tests were carried out under UV-A irradiation using five selected organic dyes. The results indicate that the activity of TiO2–M is more important for cationic dyes, where the removal rates are in the order: crystal violet (97.1%) > methylene blue (93.20%) > rhodamine B (79.8%) > methyl orange (36.1%) > Congo red (22.6%). The results of the TiO2– M activity were compared with that of the commercial P25. The comparison demonstrates that the synthesized TiO2–M exhibits a higher adsorptive behavior and can be used as low-cost alternative to the commercial TiO2 for wastewater treatment, showing also an extreme easiness to completely recover the composite catalyst at the end of the test.