Adsorption and Photocatalytic Degradation of Methylene Blue on TiO<sub>2</sub> Thin Films Impregnated with Anderson-Evans Al-Polyoxometalates: Experimental and DFT Study
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Date
2023
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Abstract
In this work, we fabricated a TiO2 thin film,and thesame film was modified with an Anderson aluminum polyoxometalate (TiO2-AlPOM). Physical-chemical characterization of thecatalysts showed a significant change in morphological and opticalproperties of the TiO2 thin films after surface modification.We applied the kinetic and isothermal models to the methylene blue(MB) adsorption process on both catalysts. The pseudo-second ordermodel was the best fitting model for the kinetic results; qe (mg/g) was 11.9 for TiO2 thin films and 14.6for TiO2-AlPOM thin films, and k (2) (g mg(-1) min(-1)) was 16.3 x10(-2) for TiO2 thin films and 28.2 x10(-2) for TiO2-AlPOM thin films. Furthermore,the Freundlich model was suitable to describe the isothermal behaviorof TiO2, K (F) (5.42 mg/g), and1/n (0.312). The kinetics of photocatalytic degradationwas fitted using the Langmuir-Hinshelwood model; k (ap) was 7 x 10(-4) min(-1) for TiO2 and 13 x 10(-4) min(-1) for TiO2-AlPOM. The comparative studyshowed that TiO2 thin films reach a 19.6% MB degradationunder UV irradiation and 9.1% MB adsorption, while the TiO2-AlPOM thin films reach a 32.6% MB degradation and 12.2% MB adsorptionon their surface. The surface modification improves the morphological,optical, and photocatalytic properties of the thin films. Finally,the DFT study supports all the previously shown results.