The degradation of acid red 14 (AR14), commonly used as a textile dye, can be photocatalysed by ZnO. Using advanced oxidation processes (AOPs), zinc oxide appears to be a suitable alternative to TiO2 for water treatment. In this study, a detailed investigation of photocatalytic degradation of acid red 14 is presented. Photodegradation efficiency was small when the photolysis was carried out in the absence of ZnO and it was also negligible in the absence of UV light. The semi-log plot of dye concentration versus time was linear, suggesting first order reaction (K=0.0548 min−1). The effects of some parameters such as pH, amount of photocatalyst, hydrogen peroxide and ethanol concentration were also examined. The addition of proper amount of hydrogen peroxide improved the decolorization, while the excess hydrogen peroxide could quenched the formation of hydroxyl radicals ( OH). As our results indicated that ethanol inhibited the photodegradation of dye, we concluded from the inhibitive effect of ethanol that hydroxyl radicals played a significant role in the photodegradation of dye. This should not undermine direct oxidation caused by positive holes.

Photocatalytic degradation of azo dye acid red 14 in water on ZnO as an alternative catalyst to TiO2

Acid Red 14 (AR14), commonly used as a textile dye, could be photocatalytically degraded using TiO 2 suspensions irradiated by a UV-C lamp (30 W). The experiments showed that TiO 2 and UV light had a negligible effect when they were used on their own. The semi-log plot of dye concentration versus time was linear, suggesting first order reaction ( K =1.41×10 −2  min −1 ). The effects of some parameters such as pH, the amount of TiO 2 and initial dye concentration were also examined. The photodegradation of AR14 was enhanced by the addition of proper amount of hydrogen peroxide, but it was inhibited by ethanol. From the inhibitive effect of ethanol it was deducted that hydroxyl radicals played a significant role in the photodegradation of dye, but a direct oxidation by positive holes was probably not negligible. Accordingly, it could be stated that the complete removal of color, after selecting optimal operational parameters could be achieved in a relatively short time, about 3.5 h.

Photocatalytic degradation of azo dye acid red 14 in water: investigation of the effect of operational parameters

Topics, in alphabetical order from “Activity”, “Band structure” and “Crystallinity” to “X-ray photoelectron spectroscopy”, “Yield” and “Z-scheme photocatalysis”, related to photocatalysis and photoelectrochemical reaction are discussed with interpretation of what we know and what we do not know in a scientific sense.

https://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/47047/3/JPPC11-4_157-178.pdf

Photocatalysis A to Z—What we know and what we do not know in a scientific sense

The effect of operational parameters on the photocatalytic degradation of acid red 18 by ZnO

Effect of deposition of Ag on TiO2 nanoparticles on the photodegradation of Reactive Yellow-17

In this study the photocatalytic destruction of phenol in an aqueous suspension of illuminated TiO 2 was investigated. The experiments were carried out using a Pyrex annular photoreactor. The effects of some parameters such as pH, loading of TiO 2 , flow rate of O 2 and temperature on the photocatalytic destruction rate of phenol were examined. It was observed that the flow rate of O 2 has no considerable effect on the destruction of phenol over the range of 2-3.5 L/min. The photodestruction of phenol followed the pseudo first-order kinetics of the Langmuir-Hinshelwood model giving an activation energy of 16.2 kJ/mol.

M. Erol

Papers

Photocatalytic Destruction of Phenol by TiO2 Powders