Characterization and photocatalitical properties of ZnO nanoparticles processed by high energy ball milling in a shaker mill

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Abstract
06-002 Ana Gabriela Storion Storion, A.G.(Universidade Federal de Alfenas); Pallone, E.M.(Faculdade de Zootecnia e Engenharia de Alimentos - FZEA); Dias, J.A.(UNIVERSIDADE FEDERAL DE SÃO CARLOS); Giraldi, T.R.(Universidade Federal de Alfenas); Maestrelli, S.C.(Universidade Federal de Alfenas-campus de Poços de Caldas); Advanced Oxidation Processes (AOP) are widely studied as alternative water treatments, once conventional processes proved to be inefficient over time for some contaminants. Heterogeneous photocatalysis, a method of AOP, consists in the activation by radiation of a semiconductor, leading to electronic transitions between its valence and conduction band, generating oxidizing and reducing sites which will trigger reactions for mineralization of the polluting compounds. The surface area of a photocatalyst is a factor of extreme importance, since the photocatalytic processes will activate and occur on its surface, which makes it interesting to study processes of obtaining powders on a nanometric scale. High energy ball milling (HEBM) can be cited as an alternative processing in this context. Despite its easy processing, low cost and the non-use of toxic solvents, it can contaminate the products obtained due to the wear of the material used for the grinding medium. The present work aimed to study the application of HEBM performed in a SPEX 8000 Mixer/Mill, with ball to powder weight ratio of 5:1, to reduce the particle size of ZnO at nanometric scale to evaluate its photocatalytic activity in the decomposition of organic pollutants, using Rhodamine B (RhB) as contaminant model. The powder was previously characterized and submitted to the milling process of 1, 2, 3, 4 and 5 hours. After milling, acid leaching was applied to decontaminate the iron from the grinding medium, using 0.5M Oxalic Acid. The powders proceeded to X-ray diffraction and FTIR. Finally, photocatalytic tests were carried out in a photochemical reactor with incidence of ultraviolet radiation. The results showed that HEBM using SPEX 8000 Mixer/Mill presents enormous potential in obtaining powders in nanometric scale; however, the deformations induced in the processed powder caused losses in its photocatalytic potential. The authors thank FAPEMIG and CAPES for the financial support to this research.
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