Adjustment and Application of the Band Gap of Nano Titanium Dioxide: Its Usefulness on Photo degradation of Wastewater (phenol)

    A high concentration of phenol and its derivatives were found in the surface water of the Euphrates River in south Iraq's Nasiriya city causing its pollution from the wastewater derived from different chemicals. This study includes modification of the TiO2 (anatase) bandgap by doping with platinum atoms using the sol-gel method. The modification would reduce the gap separating energy levels between conduction band CB and valance band VB, which in turn, would facilitate the transfer of excited electrons from VB to CB. Absorption of the energy from incident photons having the same or larger energy than that of the bandgap would promote the formation of the couple (electron-hole). The resulting (e-/h+) couple would act to produce (˙OH) radicals. ˙OH radicals haze a power with full capacity to destroy organic pollutants in the water that are absorbed on the surface of the photocatalytic TiO2. The structure of prepared TiO2 powders was dulcified using XRD, the particle size and their distribution were characterized using Atomic Force Microscopy (AFM). The photocatalytic reaction was followed out using ATR-FTIR, UV-Vis spectrophotometry. The effect of the weight of the photocatalytic catalyst (TiO2) from (0.10 – 0.83 g. L-1) was studied to monitor its effect on the rate of decomposition of phenol on the pre-determined aqueous solution of the compound. The most effective weight was found to equal (0.43 g. L-1). The activities of TiO2 (anatase) and doped TiO2 with platinum were studied under the influence of a source of UV light and direct sunlight under the same conditions. The results revealed that the reaction obeys first-order kinetics having a rate constant of 4.69x10-6 min-1 for TiO2 and 9.44x10-6 min-1 for doped TiO₂.