The rapid development of the fluorinated pesticide industry has produced a large amount of fluorine-containing hazardous waste, especially inorganic fluoride-containing waste（IFCW）. A two-step process, including ext...The rapid development of the fluorinated pesticide industry has produced a large amount of fluorine-containing hazardous waste, especially inorganic fluoride-containing waste（IFCW）. A two-step process, including extraction and recovery, was developed to recover fluorine as synthetic cryolite from IFCW produced by the pesticide industry. The optimum conditions for extraction were found to be a temperature of 75℃, an initial p H（p Hi） of 12, a4-hr incubation time and a liquid-to-solid ratio of 40 m L/g; these conditions resulted in a fluorine extraction ratio of 99.0%. The effects of p H and the F/Al molar ratio on fluorine recovery and the compositional, mineralogical and morphological characteristics of the cryolite products were investigated. Field-emission scanning electron microscopy of recovered precipitates showed changes in morphology with the F/Al molar ratio. Coupling Fourier transform and infrared spectroscopy, X-ray diffraction indicated that the formation of Al F3-6was restricted as increasing p H. Both the amount of fluorine recovered and the quality of the cryolite were optimized at initial p H = 3 and a F/Al molar ratio 5.75. This study proposed a reliable and environmentally friendly method for the treatment of fluoridecontaining wastes, which could be suitable for industrial applications.展开更多
基金supported by the Hi-Tech Research and Development Program (863) of China (No. 2007AA061300)the Innovation Program of Undergraduate Students in Shanghai Province (No. 0400107092)Collaborative Innovation Center for Regional Environmental Quality
文摘The rapid development of the fluorinated pesticide industry has produced a large amount of fluorine-containing hazardous waste, especially inorganic fluoride-containing waste（IFCW）. A two-step process, including extraction and recovery, was developed to recover fluorine as synthetic cryolite from IFCW produced by the pesticide industry. The optimum conditions for extraction were found to be a temperature of 75℃, an initial p H（p Hi） of 12, a4-hr incubation time and a liquid-to-solid ratio of 40 m L/g; these conditions resulted in a fluorine extraction ratio of 99.0%. The effects of p H and the F/Al molar ratio on fluorine recovery and the compositional, mineralogical and morphological characteristics of the cryolite products were investigated. Field-emission scanning electron microscopy of recovered precipitates showed changes in morphology with the F/Al molar ratio. Coupling Fourier transform and infrared spectroscopy, X-ray diffraction indicated that the formation of Al F3-6was restricted as increasing p H. Both the amount of fluorine recovered and the quality of the cryolite were optimized at initial p H = 3 and a F/Al molar ratio 5.75. This study proposed a reliable and environmentally friendly method for the treatment of fluoridecontaining wastes, which could be suitable for industrial applications.
