Photodegradation of Congo red in aqueous solution on ZnO as an alternative catalyst to TiO2

Abstract

In this research, the efficiency of ZnO and TiO 2 was compared by photocatalytic degradation of Congo red azo dye. The effects of some parameters such as pH, dye concentration and irradiation time on the degradation rate of dye solution were also examined. In addition, the aggregation feature of Congo red was studied by using UV-Vis spectroscopy techniques. The recovery of the ZnO catalyst was also investigated.

Photocatalytic oxidation of phenol red onto nanocrystalline TiO2 particles

“…Figure 9 presents typical UV-VIS spectra of three absorption bands for phenol red (10 mg l -1 ) located at 263, 432, and 590 nm. The main two visible region bands which are located at 432 and 590 nm, attributed to the chromophoric structure, whereas the band located at 263 nm is assigned to benzoic ring [26,51]. The counter-intuitive appearance of the band located at 590 nm in acidic medium (pH = 4.5) supports the high stability of the keto form, which is usual in basic medium as a keto-enol tautomerism product, due to the conjugation of the molecule.…”

Sono-intercalation of CdS nanoparticles into the layers of titanate facilitates the sunlight degradation of Congo red

“…The chemical oxygen demand (COD) values have been related to the total concentration of organics in the solution and their decrease reflects the degree of mineralization [35]. The COD analysis was carried out by standard acid dichromate method [36].…”

Removal Bismarck Brown G dye from Aqueous Solution Over a Composite of Triazole-Polyvinyl Chloride Polymer and Zinc Oxide

“…It is well known that phtocatalytic reactions are not too sensitive towards elevation in reaction temperature and it depend mainly on electron transfer from valence band into the conduction band through structure of particles of the catalyst. It is believed that enhancement in the efficiency of dye removal with increasing of reaction temperature is probably attributed to the effect of temperature on the diffusion of dye molecules from bulk solution to the surface and its effect on adsorption-desorption processes for reacting species 35,36 .…”