Removal of methylene blue in a photocatalytic reactor using polymethylmethacrylate supported TiO2 nanofilm

In this study, methylene blue (MB) was chosen as a model dye to test a novel photocatalytic reactor using titanium dioxide (TiO2) nanofilm. TiO2 photocatalysis is a light-activated process that has been successfully applied to remove organic and inorganic pollutants from water and wastewater. The reactor, made of stacked polymethylmethacrylate (PMMA) rings coated with a thin-film of TiO2 produced using a sol–gel method, operated in cycles from 2 to 77 h in a recirculation mode (by means of a pump and 2 L reservoir) under various conditions (with/without catalyst, with/without UV radiation, different pH conditions, after reactor reactivation by UV radiation). The MB removal efficiency was evaluated using UV absorbance at 664 nm. MB removal efficiency results (80% after 10 min at pH 9) show that TiO2 photocatalysis provides a promising technology to improve the quality of effluent from textile wastewater treatment plants. However, fouling and reactivation of photocatalyst are issues to be considered in order to evaluate the possibility in using the photocatalytic process for wastewater treatment.

This study focused on the evaluation of methylene blue (MB) removal by means of a novel photocatalytic reactor made of stacked polymethylmethacrylate (PMMA) rings coated with a thin-film of TiO2 prepared using a sol–gel method. The system operated in a recirculation mode under various conditions (with/without catalyst, with/without UV radiation, different pH conditions, after reactor reactivation by UV radiation). Changes in MB concentration (UV664 peak area) at pH 7 amounted to 24 and 48% after 1 and 3 h, respectively. At pH 9, removal efficiency reached 80% after 10 min. The increased removal at pH 9 is due to the photocatalyst surface becoming negatively charged at pH values higher than the point of zero charge, coupled with the cationic charge of MB at these pH values. These results show that TiO2 photocatalysis provides a promising technology to improve the quality of effluent from textile wastewater treatment plants. However, fouling and reactivation of the photocatalyst are issues to be considered in order to evaluate the possibility of using photocatalysis for wastewater treatment.