Abstract

In this study, Acid Orange 7 azo dye was degraded on TiO₂ catalyst layer illuminated with ultra-violet light. The TiO₂ suspension had prior been sonicated at 20 kHz before electrophoretic deposition on smooth stainless steel surfaces, with the aim of increasing the efficiency of azo dyes degradation. The effect of sonication on the TiO₂ suspension of 10 g.L^-1 and electrophoretic deposition loading to layers on surfaces was studied. Morphological properties of the electrophoretic layers from two different suspensions, Alpha and Sigma TiO₂ were characterized by Scanning Electron Microscopy to establish the specific surface properties, particle loading and crystalline sizes. A four–position reactor was used for dye degradation experiments under Ultra Violet light at 355 nm wavelength. The degradation of the azo dye was monitored at 30minutes interval for a total of 2 hours using Ultra Violet-Visible Spectrophotometer at λ = 485 nm. It was found out that 60% of dye degradation was achieved after 120 minutes without sonication pretreatment. Sonication pre-treatment resulted in 71.42% increase on the rate of photo-degradation, at a loading of 0.32 mg/cm². Particulate layers coated with Alpha TiO₂ showed more photoactivity compared to Sigma TiO₂. Scanning Electron Microscopy indicated that Alpha TiO₂ had  50 m²/g surface area and  28 nm crystal size compared to Sigma TiO₂ with 10 m²/g and 169 nm crystal size. This study shows that sonication pretreatment of Alpha TiO₂ /UV light system is most effective in photo-degrading Acid Orange 7 dye.

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