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Iron-functionalized titanium dioxide (TiO2) composites with various Fe-to-Ti ratios were prepared on flexible glass fibers (GF-Fe-TiO2) via a sol-gel method, followed by a dip-coating process. The photocatalytic ability of these composites in degrading selected volatile organic compounds (VOCs; benzene, toluene, ethylbenzene, ando-xylene [BTEX]) at indoor concentration levels was examined. The GF-Fe-TiO2composites were characterized using scanning electron microscopy, energy-dispersive X-ray elemental analysis, ultraviolet (UV)-visible spectroscopy, and X-ray diffraction. The GF-Fe-TiO2composites showed superior photocatalytic performance to that of a reference glass fiber–supported TiO2photocatalyst for the treatment of BTEX under visible light. However, this trend was reversed under UV irradiation. Specifically, the average BTEX photocatalytic efficiencies of the 0.01-GF-Fe-TiO2composite in a 3-hr visible-light photocatalytic process were 4%, 33%, 51%, and 74%, respectively. Conversely, the average BTEX photocatalytic efficiencies obtained for GF-TiO2were close to 0%, 5%, 16%, and 29%, respectively. These findings demonstrated that the GF-Fe-TiO2composites could be applied to photocatalytically purify BTEX, especially under visible-light exposure. Moreover, the GF-Fe-TiO2composites prepared with different Fe-to-Ti ratios displayed different BTEX photocatalytic decomposition efficiencies under visible or UV light, allowing for optimization of the Fe-to-Ti ratio (which was found to be 0.01). Implications: The application of nanomaterials for air purification necessitates a supporting material to stabilize them while in contact with the treated air in the photocatalytic chamber. Glass fibers have an obvious advantage over other supporting materials mainly because of its flexibility, which makes it much easier to handle. However, the applications of glass fiber–supported, visible light–activated photocatalysts to the treatment of air pollutants are rarely reported in literature. Accordingly, this study aimed to investigate the applicability of glass fiber–supported Fe-TiO2 for the purification of VOCs under visible- as well as UV-light exposure. [ABSTRACT FROM AUTHOR]

The present study focuses on the development and feasibility of ultraviolet light emitting diode (UV-LED) source and TiO2nanotube array (TNA)-based photocatalytic reactor for Congo red (CR) dye degradation. Highly ordered TNA was synthesized by the anodization method. The synthesized highly ordered TNA was characterized by X- ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscope (AFM), and electronic impedance spectroscopy (EIS) techniques. The percentage degradation was determined using a UV–visible spectrophotometer, while the mineralization of CR dye was further confirmed by chemical oxygen demand (COD) and kinetic analysis. The effect of operational parameters such as initial concentration of dye and pH on the degradation of CR dye has been studied to determine the optimum conditions. A possible degradation mechanism based on the electrospray ionization mass spectrometry (ESI-MS) has been suggested. The results demonstrated that CR dye was completely degraded in 5 h using the designed photocatalytic reactor. The electrical energy per order (EEo) was calculated for estimating the electrical energy efficiency. The result demonstrated that highly adhered nanotube array can effectively be used for photocatalytic degradation of CR dye in the presence of UV-LED light irradiation. [ABSTRACT FROM AUTHOR]

Abstract: UV-light emitting diodes (UV-LEDs) was used for the photocatalytic degradation of Rhodamine B (RhB) dye to study the various parameters, effectiveness and feasibility for designing of photocatalytic reactor based on UV-LED irradiation in different conditions. The photocatalytic experiments were conducted using 5 UV-LED lights with same specification and Degussa P-25 TiO2 as a photocatalyst. The effects of operational parameters such as catalysts loading, initial dye concentration, pH, addition of H2O2 and effect of metal ions (Zn2+, Ag+, Fe3+, Cu2+ and Cd2+) were studied for the photocatalytic degradation of RhB. A detailed degradation pathway has been suggested, which was based on the electrospray ionization mass spectrometry (ESI-MS) analysis. It was observed that the degradation of RhB occurred via N-de-ethylation process. N-de-ethylated product was further oxidized into acids and alcohols. The complete mineralization of RhB dye (2.08×10−5 M) was confirmed by chemical oxygen demand (COD), total organic carbon (TOC), total inorganic carbon (TIC) and high pressure liquid chromatography (HPLC) analysis. The optimum conditions for higher percentage degradation of RhB dye obtained with amount of catalyst (1.6g/L), dye concentration (6.26×10−5 M) and pH=3.05. Results demonstrated that the UV-LED/TiO2 process can effectively degrade RhB dye with optimum conditions. [Copyright &y& Elsevier]