Zinc borate production in a batch reactor

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2005

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Gürhan, Deniz

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Zinc borate is a flame retardant additive used in polymers, wood applications and textile products. There are different types of zinc borate having different chemical composition and structure. In this study, the production of zinc borate that had the molecular formula of 2ZnO.3B2O3.3,5H2O was studied. The aim of this study was to investigate the effects of reaction parameters on the properties of zinc borate that had been synthesized by the reaction of boric acid and zinc oxide at the existence of the seed crystals and to determine the optimum experimental conditions for zinc borate production reaction. Reaction kinetics was also investigated to find a suitable kinetics model. The effect of boric acid to zinc oxide ratio -H3BO3:ZnO ratio- (3:1, 3.5:1, 5:1 and 7:1), the particle size of zinc oxide (10æm and 25æm), stirring rate (275 rpm, 400 rpm, 800 rpm and 1600 rpm), temperature (75°, 85° and 95°) and size of seed crystals (10æm and smaller size) on reaction rate, reaction completion time, composition and particle size distribution of zinc borate were investigated. Experiments were performed in a continuously stirring, temperature controlled batch reactor with a volume of 1.5L. During the experiments samples were taken to be analyzed in regular time intervals. The analyses of the samples gave the concentration change of zinc oxide and boron oxide in the solid as well as the conversion of zinc oxide to zinc borate with respect to time and the rate of reaction was calculated. The products were also analyzed for particle size distribution. The experimental results showed that the reaction rate increased with the increasing H3BO3:ZnO ratio, particle size of zinc oxide, stirring rate and temperature. The reaction completion time was also decreased by increasing H3BO3:ZnO ratio, stirring rate and temperature. The particle size of final product, zinc borate, decreased with

Subject Keywords

Chemical engineering.

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http://etd.lib.metu.edu.tr/upload/3/12606996/index.pdf
https://hdl.handle.net/11511/15462

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Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

D. Gürhan, “Zinc borate production in a batch reactor,” M.S. - Master of Science, Middle East Technical University, 2005.