Potential release of hydrogen fluoride from domestic coal in endemic fluorosis area in Guizhou, China

Abstract

Almost half of the total rural area of Guizhou Province and many regions within the 11 adjacent provinces in southwestern China have a long history (at least 70 years) of endemic fluorosis, including dental fluorosis and osteofluorosis along with its associated deformities and disabilities. Over decades of research, this specific type of endemic fluorosis has been defined as coal-burning fluorosis, which is distinct from drinking-water fluorosis. It is generally acknowledged that indoor burning and combustion of high-fluorine coal leads to food contamination, and fluorine then enters the human body. However, the exact chemical form of fluorine during its release and transfer to the body is still unknown. In the present study, 21 domestic coal samples from outcrop and semi-outcrop coal collected in five villages with fluorosis were analyzed by time-of-flight secondary ion mass spectrometry (TOF-SIMS). The total mass fraction of sulfur in the samples ranged from 0.24%-5.58% and total fluorine content ranged 90.2-149.2 mg/kg. H 3 O + , H 2 SO 4 + and HSO 4  were detected in the samples by TOF-SIMS, which indicated that sulfuric acid hydrate (H 2 SO 4 ·H 2 O) was present in the samples. F -was detected in all of these, which suggested the samples contain ionic fluorine compounds. Under certain circumstances, such as heating or burning, the prevalence and coexistence of the acid (H 2 SO 4 ·H 2 O) and base (F -) would lead to a neutralization reaction producing volatile hydrogen fluoride (HF, bp = 19.5°C). This would be the chemical form of fluorine released from the coal. Further studies using HF and SO 2 test tubes on headspace gas over coal samples heated to 200°C in the laboratory and on headspace gas over stoves or chimney tops at rural residences confirmed the release of HF. endemic fluorosis, hydrogen fluoride, sulfuric acid hydrate, time-of-flight secondary ion mass spectrometry, Guizhou Citation: Liang H D, Liang Y C, Gardella J A Jr, et al. Potential release of hydrogen fluoride from domestic coal in endemic fluorosis area in Guizhou, China.

Removal of Fluoride from Water by Five Submerged Plants

“…Fluorosis in general, has been identified in various countries (Sinha et al 2000). Almost half of the rural areas of Guizhou province and many regions within the 11 adjacent provinces in southwestern China have a long history (at least 70 years) of endemic fluorosis, including dental fluorosis and osteofluorosis along with its associated deformities and disabilities (Liang et al 2011). Unless effectively controlled, industrial F -emissions, especially from phosphate fertilizer plants and plants producing aluminum, iron, glass, and ceramics, are significant environmental hazard to the biocenosis of water ecosystems (Maria et al 2001).…”

Analysis of multiple pathways and levels of fluoride intake in fluorosis areas of Southwest China

“…Consequently, developmental defects of the tooth are referred to as coal-burning dental fluorosis [ 4 ]. Extensive investigations have revealed that the fluoride levels of coal used in most places are generally lower than the national average [ 5 , 6 ]. Except for a few regions with high fluoride content in coal, this pathway is not the only contributor to the prevalence of dental defects in China [ 7 ].…”

Weathering of Clay-Pyrite of Coal-Bearing Formation in the Endemic Fluorosis Area of Southwest China

“…Using time-of-flight secondary ion mass spectrometry (TOF-SIMS) combined with on-site coal combustion tests, Liang et al [27] verified that naturally outcropping coal, commonly used by locals, was rich in sulfuric acid. This led to the proposition of a new perspective: during usage of coal-fired systems, sulfuric acid facilitates the release of fluorine in the form of hydrogen fluoride (HF), which then pollutes the environment.…”