title: Treatment and resource recovery from inorganic fluoride-containing waste produced by the pesticide industry.
abstract: 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°C, an initial pH (pHi) of 12, a 4-hr incubation time and a liquid-to-solid ratio of 40mL/g; these conditions resulted in a fluorine extraction ratio of 99.0%. The effects of pH 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 AlF6(3-) was restricted as increasing pH. Both the amount of fluorine recovered and the quality of the cryolite were optimized at initial pH=3 and a F/Al molar ratio 5.75. This study proposed a reliable and environmentally friendly method for the treatment of fluoride-containing wastes, which could be suitable for industrial applications.
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, Tongji University, Shanghai 200092, China. Electronic address: sqqsli@126.com.
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, Tongji University, Shanghai 200092, China. Electronic address: zhanghua_tj@tongji.edu.cn.
authors.forename: Hua
authors.initials: H
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, Tongji University, Shanghai 200092, China.
authors.forename: Zhiqi
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Institute of Waste Treatment and Reclamation, Tongji University, Shanghai 200092, China; Research and Training Center on Rural Waste Management, Ministry of Housing and Urban-Rural Development of P.R. China, Shanghai 200092, China.
authors.forename: Liming
authors.initials: L
authors.lastname: Shao
authors.affiliation: Institute of Waste Treatment and Reclamation, Tongji University, Shanghai 200092, China; Research and Training Center on Rural Waste Management, Ministry of Housing and Urban-Rural Development of P.R. China, Shanghai 200092, China.
authors.forename: Pinjing
authors.initials: P
authors.lastname: He
mesh_terms: D005591:Chemical Fractionation; D011232:Chemical Precipitation; D005459:Fluorides / Q000737:chemistry*; D007220:Industrial Waste / Q000032:analysis*; D010575:Pesticides / Q000737:chemistry*; D059027:Recycling
chemical_list: D007220:Industrial Waste; D010575:Pesticides; D005459:Fluorides
keywords: Cryolite; Fluoride-containing waste; Fluorine extraction; Fluorine recovery