| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 642265 | Separation and Purification Technology | 2012 | 13 Pages |
Commercial TiO2 was impregnated with silver nanoparticles at 1 and 2 mol% Ag using a simple ‘liquid impregnation followed by heat treatment’ method and the material was characterized using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM)/energy dispersive X-ray (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman, diffusive reflectance spectroscopy (DRS), and BET surface area/pore volume analysis. Impregnation of silver nanoparticles on P25 TiO2 was done using the same procedure. Commercial TiO2 was also modified under simple heat treatment to make combusted TiO2. To probe the challenge of photodegradation of a known carcinogen, malachite green (MG), we have investigated the UV-induced photodegradation of MG in aqueous medium using all these modified TiO2 catalysts in order to evaluate the effect of silver impregnation. We report that the presence of silver in TiO2 enhances the photon induced mineralization of MG but reduces the decolorization efficiency. Based on both decolorization and mineralization, and also on the cost and availability, 1% silver impregnated commercial TiO2 was found the optimal. The degradation of MG using this catalyst has been investigated in a more detail, and the effect of pH, stirring, initial MG concentration, catalyst dose, nature of light, and the presence of interfering ions/organics are examined. The dye (∼25 mg/l) is bleached almost completely upon 1 h of light irradiation under experimental conditions. The degradation follows zero-order kinetics over the entire MG concentration range (25–125 mg/l), and we presume that the degradation occurs via step-wise N-demethylation. Most importantly, we observe high turn over frequency (TOF) for our catalyst. This makes the catalytic process cost-effective and the catalyst recycle able. Further, a cost-analysis is made to evaluate the proper selection of the catalyst in terms of efficiency and economy.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Nano silver impregnation of commercial TiO2 and P25 TiO2. ► Modification of commercial TiO2 on heat treatment. ► Use of TiO2 based materials for photocatalytic degradation of malachite green (MG). ► Comparative performance evaluation of the catalysts. ► Effect of varying condition on MG degradation using Ag impregnated commercial TiO2.
