# Immobilized TiO\({}_{2}\)-Polyethylene Glycol: Effects of Aeration and pH of Methylene Blue Dye
## 3 Result and Discussion  
### FT-IR and XPS Analysis of Immobilized TiO\({}_{2}\) and TiO\({}_{2}\)/PEG  
The FT-IR spectra of immobilized TiO\({}_{2}\) and TiO\({}_{2}\)/PEG were determined and are presented in Figure 2a. The spectra revealed a strong and sharp absorption peak at 1705.02 cm\({}^{-1}\) which is attributable to the existence of C=O bond in immobilized TiO\({}_{2}\)/PEG sample. At the lower wavenumber of 1160.06 cm\({}^{-1}\), another bond was discovered corresponding to the stretching vibration of carbonyl oxygen or the C-O bond. However, the C=O and C-O bonds were not found in the immobilized TiO\({}_{2}\) sample. These newly-discovered peaks observed in immobilized TiO\({}_{2}\)/PEG were the result of the introduction of high molecular weight PEG 6000 into the immobilized sample. The oxidation of PEG 6000 in washed film was detected owing to the strong absorption by the carbonyl group in the FT-IR spectrum [29]. The strong absorption peaks of C=O and C-O bonds represent a successful interaction of TiO\({}_{2}\) nanoparticles with PEG 6000 that favours good photocatalytic activity, as shown previously. The surface analysis of immobilized TiO\({}_{2}\)/PEG was also studied by X-ray photoelectron spectroscopy, as displayed in Figure 2b. In this study, the C1s spectra of XPS analysis revealed the significant presence of a C=O bond according to its characteristic binding energy at 288.7 eV. Other peaks detected were found to be C-O bond and C-C bond observed at 286.7 and 284.8 eV, respectively. This finding is very important because C=O and C-O bonds were the two main species responsible for the w  
Figure 2: The spectrum for: (**a**) the Fourier transform infrared spectroscopy (FT-IR) for immobilized TiO\({}_{2}\) and TiO\({}_{2}\)/PEG samples; and (**b**) X-ray photoelectron spectroscopy (XPS) deconvolution peaks of C1s for immobilized TiO\({}_{2}\)/PEG. of TiO\({}_{2}\) photocatalyst in the VL spectrum [30]. Due to the C=O and C-O bonds in immobilized TiO\({}_{2}\)/PEG, the immobilized sample is able to have a good photoactivity efficiency under both NL and VL irradiation. The bonds act as electron injectors that speed up the photodegradation process when they are adsorbed on TiO\({}_{2}\) surface and become excited by VL. From here, new electrons are formed and are injected to the conduction band of the TiO\({}_{2}\) photocatalyst. The conduction band transferred the electrons from the bonds to electron acceptors on the immobilized TiO\({}_{2}\)/PEG surface. The excited electrons in the conduction band then performed a series of chain reactions that contribute to enhanced performance of immobilized TiO\({}_{2}\)/PEG under VL spectrum. Photoactivity Tests of Immobilized TiO\({}_{2}\) and TiO\({}_{2}\)/PEG under Different Light Irradiations  
The degradation of MB dye under NL and VL irradiations was used to study the photocatalytic activity of immobilized TiO\({}_{2}\) and TiO\({}_{2}\)/PEG samples. Under identical conditions, it was found that only 18.7% of MB dye solution was adsorbed on the immobilized TiO\({}_{2}\) in the dark after 30 min, while the amount of MB removed by the TiO\({}_{2}\)/PEG was 47.4% [26]. This suggests that the greater adsorption of MB on TiO\({}_{2}\)/PEG as compared to immobilized TiO\({}_{2}\) is attributed to the higher surface area of TiO\({}_{2}\)/PEG (Brunauer-Emmett-Teller (BET) surface area of the photocatalysts: TiO\({}_{2}\)/PEG, 88 m\({}^{2}\)/g; TiO\({}_{2}\), 49 m\({}^{2}\)/g). As can be seen in Figure 3a, the immobilized TiO\({}_{2}\)/PEG sample exhibited higher photocatalytic activities than immobilized TiO\({}_{2}\) under NL irradiation, with the dye remaining for immobilized TiO\({}_{2}\)/PEG being 0.29 as compared to 0.58 for immobilized TiO\({}_{2}\) in 15 min of irradiation time. At this stage, the photoactivity efficiency of immobilized TiO\({}_{2}\) was proven to be two times better than immobilized TiO\({}_{2}\).