화학공학소재연구정보센터
Journal of Hazardous Materials, Vol.187, No.1-3, 473-479, 2011
Vaporization of zinc during thermal treatment of ZnO with tetrabromobisphenol A (TBBPA)
In the present work we investigate the vaporization of zinc or its compounds during thermal treatment of ZnO with tetrabromobisphenol A. Samples of 2 g of ZnO:TBBPA (3.34:1) were isothermally heated in a laboratory-scale furnace at temperatures from 490 degrees C to 950 degrees C, and the solid, condensed and gaseous products formed were analyzed by X-ray diffraction analysis, electron probe microanalysis, inductively coupled plasma analysis, ion chromatography, and gas chromatography coupled with mass spectrometry. The results obtained indicate that the vaporization of ZnBr2 formed strongly depends on heating time and temperature, yet is restrained by char, if formed with sufficient yield (above 15 wt%). Starting from 850 degrees C, this char commences carbothermic reduction of any remaining ZnO, which from then begins to evaporate as zinc metal vapor. Volatilization of zinc is completed at 950 degrees C. The presence of 5 vol.% of oxygen has no significant effect on the vaporization of formed ZnBr2, the carbothermic reduction or the volatilization of metallic zinc. Strongly oxidizing conditions (20 vol.% of oxygen), however, boost the oxidation of char and thus the vaporization of ZnBr2, but prevent carbothermic reduction of any un-reacted ZnO by depleting this char. (C) 2011 Elsevier B.V. All rights reserved.