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J Environ Sci (China). 2015 May 1;31:21-9. doi: 10.1016/j.jes.2014.10.016. Epub 2015 Mar 11.

Treatment and resource recovery from inorganic fluoride-containing waste produced by the pesticide industry.

Author information

1
State Key Laboratory of Pollution Control and Resources Reuse, Tongji University, Shanghai 200092, China. Electronic address: sqqsli@126.com.
2
State Key Laboratory of Pollution Control and Resources Reuse, Tongji University, Shanghai 200092, China. Electronic address: zhanghua_tj@tongji.edu.cn.
3
State Key Laboratory of Pollution Control and Resources Reuse, Tongji University, Shanghai 200092, China.
4
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.

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.

KEYWORDS:

Cryolite; Fluoride-containing waste; Fluorine extraction; Fluorine recovery

PMID:
25968254
DOI:
10.1016/j.jes.2014.10.016
[Indexed for MEDLINE]

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