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

Abstract

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-TDA, 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.

The influence of addition of a catalyst and chelating agent on the properties of titanium dioxide synthesized via the sol–gel method

“…Moreover, the decolorization of C.I. Basic Blue 9 under UV irradiation was performed, with 25 % degradation efficiency, which corresponded to the literature [51]. The measurements showed the commercial anatase titanium dioxide (A11) to have very good photooxidation activity (the efficiency of its degradation of C.I.…”

Removal of Crystal Violet and Hexavalent Chromium using TiO2-Bentonite under Sunlight: Effect of TiO2 Content

“…On the other hand, all the B-TiO 2 samples exhibit two components in this region. As already reported in our previous paper [15], the two components are a clear indication that the introduction of TiO 2 could bring about a decreasing of the basal spacing of a part of the montmorillonitic material. It is worth of note that the sample with the lowest amount of TiO 2 shows the highest relative intensity of the component at higher angles, i.e., the peak arising from the TiO 2 insertion in the basal spaces of montmorillonite.…”

“…As already reported in our previous work [15], after outgassing at RT, spectra of B-Na and B-TiO 2 samples exhibit bands in the 3700-3000 cm -1 range that can be assigned to the stretching vibration modes of all (either structural and/or surface) OH groups interacting by H-bonding. The spectroscopic counterpart of these modes can be observed at ∼1630 cm -1 (bending mode of undissociated H 2 O molecules).…”

“…The experiences of CV decolorization were carried out in pH range around 6.5 based on the results of our previous work [2]. As discussed in our previous paper [15], the morphology of this composite allows to combine both adsorption and photocatalytic reaction to remove dyes from water. In order to evaluate the contribution of adsorption and photocatalysis on the total removal for each photocatalyst, we supposed that the total removed quantity of crystal violet (under irradiation) is equal to the sum of: the adsorbed quantity in dark, the removed quantity by photolysis and the removed quantity by photocatalysis, while the latter may be calculated by subtraction.…”

“…In our previous work, we investigated the preparation of TiO 2 -Montmorillonite composite (B-TiO 2 ) by impregnation of a local sodium-bentonite (B-Na) with TiCl 4 for the decomposition of different dyes under UV irradiation [15]. Results showed that this material involves both adsorption and photocatalytic action for the removal of dyes from water, while both adsorption effectiveness and photocatalytic degradation were more pronounced for cationic dyes.…”