Novel quantification of formation trend and reaction efficiency of hydroxyl radicals for investigating photocatalytic mechanism of Fe-doped TiO during UV and visible light-induced degradation of acid orange 7.

A detailed mechanistic investigation of the hydroxyl radical (•OH) formation and organic pollutant degradation over transition metal-doped and undoped TiO photocatalysts was performed by the quantitative measurement of •OH and the identification of intermediate products under various experimental conditions. The Fe-doped TiO as a typical subject was prepared, characterized and used to degrade an azo dye Acid Orange 7 (AO7). It is indicated that the enhanced photocatalytic activity of Fe-doped TiO for AO7 degradation was attributed to the increase in surface area, the facilitated charge transfer via Fe-dopant, and a red shift of absorbable wavelength, maintaining a great formation of •OH under visible irradiation.

The use of reactive index of hydroxyl radicals to investigate the degradation of acid orange 7 by Fenton process.

This study suggested the amount of hydroxyl radicals (OH) reacting with organics as a new index to evaluate the reaction efficiency (RE) of Fenton process, and used it to investigate the degradation mechanism of target pollution, Acid Orange 7 (AO7). The effects of initial concentrations of Fe(II), HO, and AO7 on RE were quantified by using response surface methodology (RSM). The main factors affecting RE were Fe(II), HO, and their interaction, and their percentage effects were 65.

Chromate enhanced visible light driven TiO₂ photocatalytic mechanism on Acid Orange 7 photodegradation.

When hexavalent chromium (Cr(VI)) is added to a TiO2 photocatalytic reaction, the decolorization and mineralization efficiencies of azo dyes Acid Orange 7 (AO7) are enhanced even though the mechanism is unclear. This study used 5,5-dimethyl-l-pyrroline-N-oxide (DMPO) as the scavenger and the analysis of Electron Spin Resonance (ESR) to investigate this enhancement effect by observing the hydroxyl radical (OH) generation of the Cr(VI)/TiO2 system under UV and visible light (Vis) irradiation. With Cr(VI), the decolorization efficiencies were approximately 95% and 62% under UV and Vis, and those efficiencies were 25% less in the absence of Cr(VI).

Improving the indoor air quality of respiratory type of medical facility by zeolite filtering.

Unlabelled: This study investigated the indoor air quality (IAQ) conditions of carbon dioxide (CO2), carbon monoxide (CO), ozone (O3), formaldehyde (HCHO), total volatile organic compounds (TVOCs), and bio-aerosols (bacteria and fungi) in a respiratory type of medical facility in Chia-Yi County in southern Taiwan. Among those IAQ conditions, the concentrations of CO, O3, and HCHO exceeded the regulation values of the Taiwan Environmental Protection Administration (EPA) mostly in the morning. The concentrations of bacteria and fungi did not exceed the regulation values but still posed potential health and environment problems for workers, patients, and visitors.