Photodegradation study of TiO2 and ZnO in suspension using miniaturized tests

Abstract

Miniaturization has been a trend in the instrumentation of chemical analyzes. The interest in miniaturization stems from the perceived benefits of faster, easier, less expensive and less wasteful analyzes than the tradition analyses. Thus, this work proposes a miniaturization of photocatalytic tests using a microplate reader for the analysis of several results, using only microliters of solution. The present work investigates the heterogeneous photocatalysis of the eosin yellow, acid yellow 73 and basic yellow 2 dyes, in the presence of zinc oxide (ZnO) and titanium dioxide (TiO2) catalysts, under irradiation in the visible light and ultraviolet light. Dye degradation was evaluated using a microplate reader (Elisa Polaris®), a photometric device that performs colorimetric readings in the 0-3 absorbance (ABS) range at wavelengths of 405, 450, 492 and 630 nm. The kinetic study was performed using the Langmuir-Hinshelwood law. It was verified that the degradation rates were higher than 90% over a period of 120 minutes for all the studied systems, especially the system composed of acid yellow dye 73 and the ZnO catalyst, which reached a degradation of 96.23% in 120 minutes.

Optimized Degradation of Eosin Dye Through UV-ZnO NPs Catalyzed Reaction

“…Examination of this figure indicates that UV oxidation resulted in 27.43% dye degradation, compared to 45.95% for UV-ZnO NPs catalyzed process. This agrees with the work of Cambrussi et al [26].…”

Depth dependence of the photocatalytic reaction rate. kinetic model generalization

“…During the analysis of specialized literature worldwide regarding the depth dependence of photoreaction rates, studies were found on the depth dependence of methylmercury photodecomposition in coastal and oceanic waters [37], photolysis on soil surfaces [38], and the Beer-Lambert law was mentioned [14,[39][40][41][42][43]. However, nothing was mentioned regarding the current study.…”

One-step hydrothermal preparation of Ta-doped ZnO nanorods for improving decolorization efficiency under visible light

“…3,7,8 According to some reports, ZnO outperforms TiO 2 and other semiconductor oxides of photocatalytic activity, which is determined by the ability to absorb solar radiation. [9][10][11] Two primary issues that limit ZnO from being utilized as a photocatalyst are its wide bandgap energy and the rapid recombination of electron pairs and photogenerated holes. Metal doping is one remediation method involving transition metals such as Mn, Co, Fe, Cu, Mg, and Ta, [12][13][14][15][16][17] and rare earth elements such as Er, Sm, La, Ce, Pr, Er, Yb into ZnO.…”

“…3,7,8 According to some reports, ZnO outperforms TiO 2 and other semiconductor oxides of photocatalytic activity, which is determined by the ability to absorb solar radiation. 9–11…”