Synthesis and Characterization of TTIP-Al Films and Fe3+/TTIP-Al Films to be Used in Photocatalytic Oxidation under Visible Light

• Main Authors: Wipawee Dechapanya Khamwichit, Ketsara Intawong, Siriuma Jawjit
• Format: Article
• Language: English
• Published: Walailak University 2019-10-01
• Series: Walailak Journal of Science and Technology
• Subjects: TTIP; Fe-doping; Anodization; Photocatalytic oxidation; Color degradation; Rubber wood process
• Online Access: http://wjst.wu.ac.th/index.php/wjst/article/view/6551

The objective of this research is to synthesize and characterize the TTIP-Al films and the Fe3+/TTIP-Al films to be used in photocatalytic oxidation under visible light.  The synthesized films will be further used in the study of color degradation for chemical solution used in the rubber wood process. To prepare the films, aluminum sheets with the size of 25 mm x 35 mm x 0.002 mm were cleaned with 1 M NaOH solution before being anodized with the voltage of 50 V and 0.2 A for 25 mins. The anodization was used to increase pore size and roughness of the films for improving the catalyst stabilization on the aluminum substrates. Titanium isopropoxide (TTIP) was mixed together with ethanol and later on with ferric chloride hexahydrate for the preparation of TiO2-Fe3+ solution to be used in the sol-gel and dip coating method.  The solution was diluted with 500 ml distillated water and pH was adjusted to be 2 using HCl, then stirred at 800 rpm for 1 h before refluxing at 121 oC for 2 h in an autoclave. For the TTIP-Al films, the gel solution was repeated as explained before with the exception of Fe3+ addition.  Anodized aluminum sheets were dipped in the gel solution for five times, then dried in a hot air oven at 60 oC for 30 mins and calcined at 100 oC for 1 h. Total of 6 different catalyst dosages of films were synthesized, including 5-ml TTIP-Al film, 10-ml TTIP-Al film, 15-ml TTIP-Al film, 5% molar Fe3+5-ml Fe3+/TTIP-Al film, 5% molar Fe3+10-ml Fe3+/TTIP-Al film, and 5% molar Fe3+15-ml Fe3+/TTIP-Al film .  Morphology of aluminum sheets and the synthesized films was analyzed using SEM. Results revealed that anodization clearly enhanced pore size and roughness of the film surfaces.  Pore sizes with the diameter ranges from 19.77 – 45.84 nm were found on the anodized aluminum films. Thickness of catalysts on aluminum film surfaces was approximately 1.3, 2.6, and 3.1 µm for 5-, 10-, and 15-ml TTIP-Al films. Meanwhile, thickness of co-doped catalysts (Fe3+/TTIP-Al films) decreased a little bit from those of TTIP-Al films (1, 1.3, and 3 µm, respectively). The analysis of XRD indicated that crystal of Anatase Titanium dioxide at 25.5° 2 Theta was observed, in which the higher dosage of TTIP resulting in higher peak intensity.  Crystal of Fe3+ was not observed which may be explained that Fe3+ ions are potentially substitute in Ti4+ site with TiO2. Results from the UV-VIS analysis suggested that absorbed wavelengths for Fe3+/TTIP-Al films shifted to visible light (410 nm) compared to those of TTIP-Al films (380 nm).  FT-IR Spectra analysis of the Fe3+/TTIP-Al films showed the group of hydroxyl radical on Fe3+/TiO2 surface. This functional group could affect the efficiency of photocatalytic oxidation.  Color removal of chemical solution in rubber wood pressed process using these films in annular photocatalytic reactor will be studied in the next phase of this work.