Study on the Photocatalytic Effect of Heteroplyacid-Titania Nanocomposites On methylene blue degradation

Today industrial development and environmental contamination need greatest concerns and should be removed for environmental and human health protection [1]. One of the big environmental problems is wastewaters containing various types of pollutants such as organic dyes which produced by pesticides, petrochemicals and etc. so they have high toxicity, slow biodegradation and potential carcinogenicity [2]. At present several industrial techniques such as oxidation, adsorption, precipitation, degradation and so on have been used which cost much money and create another type of pollutions. Photocatalysts as an effective techniques have potential in this area [3]. Titanium dioxide (TiO2) in combination with heteropolyacids (HPA) as semiconductor nano composite under UV irradiation could effectively concerns for pollution reduction [4-6]. Some HPAs, (Molybdophosphoric acid, tungstophosphoric acid, silicotungstic acid) and HPA/TiO2 nano composites were synthesized as a green, cheap and solid acid catalyst by impregnation method. Nano composites were characterized by Fourier transform infrared (FTIR), powder X-ray diffraction (XRD), scanning electron microscopy (SEM). We designed a UV illumination box to degrade methylene blue as a common azo dye pollutant in the environment. The photocatalytic degradation was investigated under UV, visible and dark illumination. The special effects of dye concentration, HPA loadings, catalyst dose, temperature and pH value were investigated. Heterogeneous HPA/TiO2 nano composites showed good photo-degradation of methylene blue under UV irradiation and room temperature with 98% yield. Nano composites can be separated and recovery from reaction media.