Modeling of Advanced Photo Oxidation of Alizarin Red-S Dye Using Tio2 as Photo Catalyst

The objective of this study was to investigate the experimental study and theoretical study of advanced photo oxidation using TiO2 as photo catalyst and to compare between these two studies. This work contains two parts, the first part was removing efficiency of an industrially important dye Alizarin Red-S (ARS) from aqueous media using TiO2 anatase as photo catalyst was studied in various conditions, such as initial concentration, temperature, pH, photo catalyst dosage.

The second part deals with the theoretical study of the TiO2 surface and the pollutant substance (ARS) using the program (Spartan '08 V1.2.0). we used two kinds of calculations, the first was the Equilibrium Geometry optimization at ground state by Density Functional Theory/B3LYP method and Semi-empirical/PM3 method to predict the most stable geometrical formula for TiO2 anatase (001),(101) and (ARS) pollutant in different medium (neutral, acidic, basic). The program showed that the method DFT/B3LYP give the best results compared with DFT/PM3 and that the basic medium was better than acidic and neutral medium which means that the highest rate of (ARS) degradation was in basic medium. The second calculation was the energy geometry at ground state by density functional theory/EDF2 method to calculate standard thermodynamic quantities for (ARS) pollutant and TiO2 anatase (001), (101) surface that showed the highest stability for them in the basic medium.

The results from theoretical study agreed with the results obtained in the experimental study. Results from the experimental study showed Thermodynamic properties was calculated for the photo degradation of (ARS) as (ΔH , ΔG , ΔS ) which is showed an exothermic heterogeneous reaction with pseudo first order reaction and optimum parameters for removal of this dye from aqueous medium were (0.16 g/l, 20ppm, temp.30ºc, pH9). Theoretical study DFT/B3LYP method showed better results than DFT/PM3 to predict the most stable geometrical formula, and TiO2 anatase (001) surface was more active than TiO2 anatase (101) surface.