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

• Preparation of TiO2–montmorillonite composite.
• Photodecolorization of five dyes using TiO2–M and P25.
• Comparison study between anionic and cationic dyes.
• Full characterization of TiO2–montmorillonite.

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.

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