Photodegradation of phenol catalyzed by TiO2 coated on acrylic sheets: Kinetics and factorial design analysis Original Research Article

The separation of nanosized titanium dioxide (TiO2) is generally required for conventional photodegradation carried out in a stirred reactor. To eliminate this step for reduction of the operating cost, this research aimed to prepare TiO2 coated on acrylic sheets via dip-coating for photodegradation of phenol. The three cycles of TiO2 coating by using acetylacetone (ACA) to TiO2 (ACA/TiO2) molar ratio of 3 gave a smooth and uniform thin TiO2 film on the surface of acrylic sheets. The effects of the number of TiO2-coated acrylic sheets, initial phenol concentration, hydrogen peroxide (H2O2) concentration and UV light power on the apparent reaction rate constant (kapp) of phenol photodegradation were also studied. Under the optimum operation, the highest kapp value of 7.2 × 10−3 min−1 was achieved. The relationship of these parameters on the phenol removal efficiency was also statistically evaluated using a two-level factorial design. The significance of reaction parameters was shown as followed: UV light power > the number of TiO2-coated acrylic sheets > initial phenol concentration > H2O2 concentration. The reduced degradation efficiency of the TiO2-coated acrylic sheets, compared to that of free suspensions, could be overcome by increasing the number of photodegradation stages, with 97.1% efficiency being attained with three photodegradation stages.