Fluorine In Water Research Articles

Removal and recovery of phosphorus and fluorine in process water from water based direct physical lithium-ion battery recycling

In the present work, the recovery of phosphorus and fluorine from process water generated in a water based direct physical recycling process of Li-ion batteries has been studied. The recycling process considered in this work produces significant amounts of process water, which is generated during the opening of the batteries by means of electro-hydraulic fragmentation and the subsequent sorting of the components in aqueous solution. This process produces between 21.6 L and 30.3 L of process water per kg of batteries with a total phosphorus and a total fluorine concentration of 60–85 mg/L and 120–470 mg/L, respectively. Currently, the process water has to be disposed of as hazardous waste. The goal is to discharge the wastewater into the sewer system. For this the total phosphorus and total fluorine concentration must be reduced. The process water is mainly contaminated by the released electrolyte consisting of organic carbonates and conducting salts. 31-P and 19-F NMR shows conclusively that no hydrolysis takes place in this process water. The phosphorus is present exclusively in the form of the complex anion PF6- and fluorine as F-, namely as FSI- from the conducting salt LiFSI and PF6- from the conducting salt LiPF6. In order to meet the regulatory requirements for discharge into the sewage system, 70.4% of the phosphorus and 89.3% of the fluorine must be removed. The conducting salts are hydrolyzed by adding acid and thereby phosphate and fluoride are precipitated. After critical and valuable materials are recovered the process water can be discharged into the sewer system.

Efficient and simultaneous immobilization of fluoride and lead in water and tea garden soil by bayberry tannin foam loaded zirconium

Nowadays, human activities intensified the combined pollution of fluoride and lead in acidic tea garden soil. The key to eliminating this combined pollution is to immobilize pollutants simultaneously, thus preventing their migration from tea garden soil to tea trees. In this paper, the natural product bayberry tannin was employed as raw material to fabricate functional materials (TF-Zr) for simultaneous adsorption of fluorine (F) and lead (Pb) in water and soil by the reactivity of tannin with Pb2+ and the affinity of Zr with F. SEM-Mapping, EDS, FT-IR, XPS were utilized to probe the immobilization mechanisms. The results showed that TF-Zr could simultaneously and efficiently adsorb F– and Pb2+ from water with the adsorption capacity of 5.02 mg/g (Pb) and 4.55 mg/g (F). The adsorption processes were both in accordance with the proposed secondary kinetic adsorption model. Besides, the presence of F– promoted the adsorption of Pb2+ by TF-Zr. The materials were applied into tea garden soil to explore its effect on the variation of F and Pb forms in the soil. It was found that the proportion of water-soluble fluorine, exchangeable fluorine and exchangeable lead in the tea garden soil decreased significantly, while the proportion of residual fluorine and lead increased evidently, illustrating TF-Zr possessed eximious fixation effect on the highly reactive fluorine and lead in the soil and facilitated their conversion to the more stable residue state. Therefore, TF-Zr can be used for the efficient and simultaneous immobilization of fluorine and lead in water and tea garden soil.

Gut microbiome and function are altered for individuals living in high fluoride concentration areas in Pakistan

BackgroundEndemic fluorosis refers to the condition when individuals are exposed to excessive amounts of fluoride ion due to living in a region characterized by elevated levels of fluorine in the drinking water, food, and/or air. In Pakistan, a substantial proportion of the population is thereby affected, posing a public health concern. ObjectivesAssessing how the gut microbiota and its metabolic profiles are impacted by chronic exposure to fluoride in drinking water (that caused Dental Fluorosis) as well as to perceive how this microbiota is connected to adverse health outcomes prevailing with fluoride exposure. MethodsDrinking water (n=27) and biological samples (n=100) of blood, urine and feces were collected from 70 high fluoride exposed (with Dental Fluorosis) and 30 healthy control (without Dental Fluorosis) subjects. Water and urinary fluoride concentrations were determined. Serum/plasma biochemical testing was performed. Fecal DNA extraction, 16S rRNA analysis of microbial taxa, their predicted metabolic function and fecal short chain fatty acids (SCFAs) quantification were carried out. ResultsThe study revealed that microbiota taxonomic shifts and their metabolic characterization had been linked to certain host clinical parameters under the chronic fluoride exposure. Some sets of genera showed strong specificity to water and urine fluoride concentrations, Relative Fat Mass index and SCFAs. The SCFAs response in fluoride-exposed samples was observed to be correlated with bacterial taxa that could contribute to adverse health effects. ConclusionsMicrobial dysbiosis as a result of endemic fluorosis exhibits a structure that is associated with risk of metabolic deregulation and is implicated in various diseases. Our results may form the development of novel interventions and may have utility in diagnosis and monitoring.

Occurrence, Main Source and Health Risks of Fluorine in Mine Water

Occurrence, Main Source and Health Risks of Fluorine in Mine Water

Fluorine (Fluoride Ion) in the Natural Waters of Karelia

Fluorine (Fluoride Ion) in the Natural Waters of Karelia

Dental health of first-year students of the Novgorod State University

Goal and objectives: to study the dental health of 1st year students of the Novgorod State University. Materials and methods: questionnaire, literature review, study of statistical data on the Russian Federation, India, Egypt, and Pakistan. An analysis of the dental health of first-year Russian and foreign students of the Yaroslav-the-Wise Novgorod State University was carried out, and factors influencing dental health were identified. Official reports on the condition and composition of tap water in the city of Veliky Novgorod and tap water in Egypt, India, and Pakistan were studied. The standards for the content of fluorine and iodine in tap water in Veliky Novgorod, Egypt, India, and Pakistan were analyzed. The influence of changing climatic conditions, quality of nutrition, and the presence of bad habits and stress on the development of dental diseases in students was considered. The World Health Organization’s global oral health status report for 2022 in the Russian Federation, Egypt, India, and Pakistan was analyzed. A survey among students of the Novgorod University was conducted in order to evaluate water in the Novgorod Region in comparison with their homeland; the survey included general health questions with an emphasis on oral hygiene. What paste, brush, and cleaning method students used when brushing their teeth, and if they visited the dentist. What dental problems they had before and what issues they have now. Conclusions: To provide recommendations on oral hygiene, the choice of oral hygiene items and products, the diet taking into account the fluorine and iodine content in the region, and daily routine.

Prevalence and risk factors of dental fluorosis among children aged 8–12 years in Shandong province of China

ABSTRACT This study was to investigate the prevalence and severity of children’s dental fluorosis (DF) in Shandong and identified the potential risk factors for DF. A total of 87 villages in Shandong were investigated to calculate the prevalence of DF and Community Fluorosis Index (CFI) in 2018–2019. Six hundred and seventy children were enrolled to identify the potential risk factors using univariate and multivariate logistic regressions. Goodman–Kruskal Gamma was used to explore the factors related to the severity of DF. In 87 villages, 1249 of 8700 (14.36%) children still have DF. The prevalence of DF in most villages was below 40% in 2018–2019. Water fluorine concentration when selected for the study and urinary fluorine concentration were related to the risk of DF (P < 0.001). Some eating habits, like lower frequency of eating fresh vegetables, eggs, and beans, were associated with the risk of DF (P < 0.001). The high water fluorine concentration, and lower frequency of eating fresh vegetables, eggs, and beans were also related to the severity of DF (P < 0.001). DF in children in Shandong province is still a common endemic disease. This study tries to provide a useful guide for the prevention and control of DF.

A fluorescence test paper fabricated by in situ growth of zirconium based MOFs for effective detection of fluoride

Fluorine as an essential trace element for human body, plays a vital role in human health. However, excessive intake, mainly through potable water, will cause adverse effects on human health. Therefore, establishing simple and effective methods for monitoring the concentration of fluorine in potable water is crucial for environmental protection and human health. In this work, a functional zirconium based MOF with excellent fluorescent detection performance was investigated. Its detection limit of F- was 0.743 ppm in aqueous solution. Based on the excellent sensitivity, a fluorescent test paper which fabricated by in situ growth of zirconium based MOF onto the surface of filter paper was following investigated. The result manifested that the test paper had an effective detection of fluorine.

Improved total organic fluorine methods for more comprehensive measurement of PFAS in industrial wastewater, river water, and air

Per- and polyfluoroalkyl substances (PFAS) are high-profile environmental contaminants, many having long persistence in the environment and widespread presence in humans and wildlife. Following phase-out of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) in North America and restrictions in Europe, PFAS replacements are now widely found in the environment. While liquid chromatography (LC)-mass spectrometry (MS) is typically used for measurement, much of the PFAS is missed. To more comprehensively capture organic fluorine, we developed sensitive and robust methods using activated carbon adsorption, solid phase extraction, and combustion ion chromatography (CIC) to measure total organic fluorine (TOF) in industrial wastewaters, river water, and air. Two extraction techniques, adsorbable organic fluorine (AOF) and extractable organic fluorine (EOF), were optimized and compared using 39 different PFAS, including replacements, such as GenX and perfluorobutanesulfonate. Our AOF method achieves 46–112% and 87% recovery for individual PFAS and PFAS mixtures, respectively, with 0.5 µg/L limit of detection (LOD) for a 50 mL sample volume and a 0.3 μg/L LOD for a 500 mL sample volume . Our EOF method achieves 72–99% and 91% recovery for individual PFAS and PFAS mixtures, respectively, with 0.2 µg/L LOD for a 500 mL sample volume and 0.1 μg/L LOD for 1200 mL. In addition to 39 anionic PFAS, two zwitterionic PFAS and two neutral PFAS were evaluated using the optimized TOF methods. Substantially higher TOF values were measured in industrial wastewater, river water, and air samples compared to LC-MS/MS, demonstrating how TOF methods provided a more comprehensive measurement of the total PFAS present, capturing known and unknown organic fluorine.

Geochemistry of fluorine in halo waters of ore fields of the southeastern part of the Dnipro-Donetsk avlakogen

The geochemical features of fluorine and its possible sources in the waters of the hydrothermal ore fields of the Dnipro-Donetsk avlakogen (DDA) are considered. It was established that the formation of anomalies occurs due to the interaction of infiltration waters of the zone of free water exchange and waters of deep formation, which are unloaded along the zones of deep faults. It is substantiated that the water migration of fluorine is determined by the geochemical type of groundwater, the degree of its mineralization, acid-base (pH) and oxidation-reduction (Eh) potentials, the presence of complex-forming elements with which fluorine forms mobile complex compounds, etc. Formulation of the problem. Fluorine is a typomorphic chemical element that is widely present in groundwater. It forms large-scale, contrasting hydrogeochemical anomalies in various types of hydrothermal ore fields, which are controlled by zones of deep faults - fluorite, mercury, polymetallic, and others. Presenting main material. Anomalies of the element are also formed in those fault zones, where the processes of modern heat and mass transfer are observed, manifested in the upward discharge of endogenous fluids against the background of increased intensity of the geothermal field. This indicates the probable arrival of fluorine in endogenous fluid flows, which are mixed with formation waters during their upward migration. The most contrasting aureoles of fluorine scattering are established in the zone of hypergenic weathering of fluorite of the Pokrovo-Kyreevsky deposit and in the aureole waters of the Mykytiv mercury ore field, in the rocks of which fluorite mineralization is absent. In them, fluorine, together with other trace elements, forms multicomponent anomalies and is part of the hydrogeochemical association of elements-indicators of hidden mercury mineralization - Hg, As, B, F, (Sb). Conclusions. 1. Geochemical features of fluorine in the processes of hydrothermal mineralization are caused by both hypogenic and hypergenic factors of its migration and concentration in the hydrolithosphere of the Dnipro-Donetsk avlakogen. 2. The high migration activity of fluorine in fluid systems and, in particular, in groundwater, is determined by numerous mobile forms of the element that exist under different geochemical conditions - in the form of gas, simple anions, complex compounds with metals, silicon, manganese, boron and other chemical elements Fluorine migrates best in alkaline sodium bicarbonate and sodium chloride waters, in which Сl–, Na+ and ОН– ions not only act as a complexing agent, but also provide high ionic strength of aqueous solutions. 3. The high content of fluorine in the waters of the Pokrovo-Kyreivsky fluorite deposit is provided by two different geochemical processes: a) hypergenic physicochemical destruction of CaF2 by gravitational infiltration waters of the zone of free water exchange; b) the influx of fluorine into deep formation waters together with endogenous fluids that are discharged along fault structures at the post-hydrothermal stage of their tectonic activation. 4. Abnormally high concentrations of fluorine in the hydrothermal mercury ore fields of the Mykytivskyi and Druzhkivsko-Kostiantynivskyi deposits, in the rocks of which there is practically no fluorite mineralization, are due to the influx of the element into the mineralization zones from deep fluid flows and underground waters of deep horizons. 5. The main natural sources of fluorine in the waters of hydrothermal deposits of the region are: a) products of hypergenic weathering of hydrothermal mineralization of fluorite; b) flows of endogenous postheterothermal fluids; c) pore solutions of sedimentary rocks of marine origin.

Sources and migration characteristics of fluorine in the river water of a small karst watershed influenced by coal mining

In high-fluorine geological background areas, the supergene geochemical process of fluorine has an impact on regional environmental health and safety, which has long been the focus of attention. However, in karst areas characterized by a high incidence of endemic fluorosis, the migration and transformation of fluorine in surface water have not received sufficient attention. This study investigated the joint influence of the weathering and erosion of carbonate rocks and coal-bearing strata on a typical small watershed. Accordingly, 239 samples representing 13 periods of hydrochemical samples were systematically collected to clarify the source, migration, and transformation characteristics of fluorine in surface water. The results revealed that the pH of the Huatan River was low in the rainy season and high in the dry season. The annual variation range of fluorine concentration was 0.11–0.40 mg/L. Although mining development produced acid mine drainage with high fluorine concentration, its impact at the watershed scale appeared to be limited. In terms of spatial scale, the concentration of fluorine in the Huatan River increased gradually from upstream to downstream. The dissolution of fluorite and other fluorine-bearing minerals had not reached the saturation state. The fluorine in the watershed primarily came from the dissolution of fluorine-bearing minerals, followed by the contribution of atmospheric precipitation. The release of fluorine adsorbed on the surface of clay minerals was not the main source of this element. The leaching of the watershed was shown to represent a critical transport process concerning fluorine in the Huatan River, and evaporation had a notable impact on the enrichment of fluorine in water.

The effect of mining development in karst areas on water acidification and fluorine enrichment in surface watersheds

High fluoride water is a crucial driving factor for endemic fluorosis. As an important research content of hydrogeochemistry, the enrichment of fluorine in alkaline water has received a fair amount of scholarly attention, but the understanding of the migration and enrichment of fluorine in acid mine drainage (AMD) in karst area remains very limited. An analysis of 13 consecutive periods of hydrochemical samples (312 samples in total) revealed that the weathering of carbonates and sulfide-rich coal measures induced a pH as low as 2.29 in the Chetian River in Jinsha, Southwest China. The highest content of fluorine in AMD was 23.8 mg/L, and the average content in the basin was 1.4 mg/L. In terms of the seasonal variation in the whole basin, the fluorine content were higher in the rainy season than in the dry season. The mineral saturation index shows that the dissolution of fluorapatite and fluorite is an important source of fluorine. The chloro-alkaline indices displayed a strong ion exchange process in the basin, promoting the release of fluorine in silicate minerals. In comparison, the contribution of external inputs, such as atmospheric deposition, was less. Additionally, evaporation was shown to have a limited influence on fluorine enrichment. Meanwhile, pH was an essential factor driving the dynamic transformation of the mode of occurrence of fluorine in water. In the upstream alkaline water, the main occurrence form of fluorine was free F−, while the F/Al ratio for most of the acidic samples was ≤ 1.0, indicating the main occurrence form of fluorine was likely AlF2+. The conclusion of this study provides a new understanding for deepening the geochemical characteristics of fluorine in karst surface water.

Recycling of phosphate tailings and acid wastewater from phosphorus chemical industrial chain to prepare a high value-added magnesium oxysulfate cement

Phosphate tailings (PT) and acid water, by-products of phosphorus chemical industrial chain, are usually identified as waste because they can hardly be reused in cement production. This paper proposes an approach of recycling solid waste PT and acid wastewater in preparing a high value-added magnesium oxysulfate (MOS) cement. Results show that the phosphorus in acid water promotes the formation of 5 Mg(OH)2·MgSO4·7H2O (517) phase, thereby improving compressive strength of MOS cement. MOS cement prepared with undiluted acid water present excellent resistance to water and acid. The incorporation of calcined PT lowers the strength of MOS cement but improves the volume stability. The phosphorus and fluorine in acid water are effectively immobilized by the cement matrix. Moreover, recycling of PT and acid water to produce MOS cement not only largely consumes the waste and benefits the environment, but also reduces the cost of waste disposal and cement production.

The Correlation Between the DMFT of the 15-year-old Children and the Concentration of Fluoride in Drinking Water from the East Region of the Republic of Macedonia

AIM: The aim of this study is to determine the correlation between the DMFT index of 15-year-old children from the east region and the concentration of fluoride in drinking water from the populated areas where children live. METHODS: In the examination, 414 children were enrolled, out of seven central secondary schools from four bigger cities from east region, at which the DMFT index was determined. The children live in six different cities and 51 different villages. Fifty-seven water samples were taken from the examined area to determine the fluoride concentration using the electrochemical method using the pH/ISE meter-Thermo-Orion with a special F-electrode (Thermo Orion Ion Plus Fluoride Electrode) at the Institute for public health. Spearman’s method was used to determine the correlation between the specified variables. RESULTS: The total number of children in the examined sample was 414, out of which 226 (54.6%) were male and 188 (45.4%) were female. The prevalence of caries free children was 9.4%. SiC index was 10.22. The average DMFT index in this group of children was 5.77 with a standard deviation of ± 4.02. Maximum concentration of fluorine in drinking water of 0.99 ppmF was determined in the village Raslovci, and 0.87 ppmF in the village Star Karaorman, while the minimum (0.07 ppmF) in the village Dvorishte and (0.10 ppmF) in the village Grad. Correlation of the DMFT index in 15-year-old children from the east region and the concentration of fluorine in the drinking water has a negative, indirect correlation, with the value of the coefficient R = −0.27. CONCLUSION: The correlation between the DMFT index and the concentration of drinking water is a negative, indirect correlation, and statistically, this correlation is highly significant (p &lt; 0.05).

The determinants of effective defluorination by the LiAl-LDHs

Millions of people in poor areas are still under the threat of fluoride contamination. How to effectively separate fluorine in water is an important step to reduce the ecological risk. In this paper, we performed a systematic DFT calculation focused on the defluorination behavior between the LiAl- and MgAl-LDHs. The results indicated that the LiAl-LDHs exhibited high chemical activity before the defluorination, because of the better electronic structure. After the defluorination, the LiAl-LDHs with adsorbed-F– were also more stable than the MgAl-LDHs. In addition, the existence of coordination covalent bond for the adsorbed-F– attached to the LiAl-LDHs was confirmed. This is an important reason for the high defluorination efficiency by the LiAl-LDHs. In addition, a series of weak interaction, including hydrogen bond and van der Waals interaction were also observed. Finally, a LiAl-LDHs with excellent fluoride removal properties were synthesized well by simple hydrothermal method. The results showed that our synthesized LiAl-LDHs with the capacity of 156.09 mg/g, could be effectively defluorinated in water. Notably, it surpasses most materials and has potential applications.

Total organic fluorine (TOF) analysis by completely converting TOF into fluoride with vacuum ultraviolet

Quantifying total organic fluorine (TOF) in water is vital in monitoring the occurrence and persistence of all fluorine-containing organic compounds in the environment, while currently most studies focus on analyzing individual fluorine-containing organic compounds. To fill the technology gap, we herein proposed to convert TOF completely into fluoride with vacuum ultraviolet (VUV) photolysis, followed by analysis of fluoride with ion chromatography. Results showed that the tailored VUV photoreactor achieved satisfying recoveries of fluorine from ten model TOF compounds not only in ultrapure water (83.9 ± 2.0% to 109.4 ± 0.8%) but also in real water samples (92.1 ± 1.0%–106.2 ± 15.7%). Unlike other ultraviolet-based processes that favor alkaline conditions, this VUV process preferred either neutral or acidic conditions to defluorinate selected compounds. While the mechanisms remain to be explored in the future, it has been evidenced that the photo-degradation and photo-defluorination rates of these TOF compounds varied significantly among compounds and operation conditions. The method obtained a method detection limit (MDL) of 0.15 μg-F/L, which is lower than the MDLs of many other TOF analytical methods, along with excellent calibration curves for concentrations ranging from 0.01 to 10.0 mg-F/L. Notably, minimizing fluoride in sample prior to photoconversion was necessary to avoid subtraction-induced errors for TOF measurement, especially when the fluoride/TOF ratio was high. The robust VUV is also green for sample pretreatment due to its unreliance of chemicals or additives.

Fluorine in the mudvolcano waters of the Kerch-Taman region

Content of dissolved fluorides in the waters of 13 mud volcanoes of the Kerch-Taman region was determined: 0,13–2,00 mg/l with average value of 0,87 mg/l (n = 37). A fairly close correlation was established between the fluorine concentration and pH value (r = 0.80) in the absence of correlation with mineralization and content of components of the basic salt composition. It was suggested that the fluorine concentration in mud-volcano waters is controlled by the exchange reaction where et is content of adsorbed and structural fluorine (hydroxyl ions) in the clay minerals; F– et OH– is concentration of fluorides (hydroxyl ions) in the aqueous phase.

Rationale behind a minimally invasive approach in the treatment of dental fluorosis

Modern epidemiology of dental fluorosis is characterized by its high global prevalence. Dental fluorosis is a chronic disease that develops before teething with prolonged ingestion of water or foods with a high content of fluorine compounds. In Russia, an increased concentration of fluorine in water is detected in more than 20 administrative regions. In addition, endemic areas can be assisted with anthropogenic factors, particularly certain chemical industry. Improvement of the novel treatment methods for fluorosis turns out to be important and relevant. For the treatment of various forms of fluorosis, sufficiently effective materials have been currently developed, characterized by convenience and ease of use, as well as safety for a patient. Their use alone or in combination allows achieving high aesthetic results and maximum patient satisfaction. The aim of this study is to measure the adhesive strength of the composite filling material to the Icon infiltrant (infiltration concept), as well as to compare it with the adhesion strength of the composite to the enamel using various adhesive systems. Icon was developed by the German company DMG and has been used worldwide since 2000. To assess the adhesive peel strength, 60 teeth with fluorosis and 60 intact teeth were examined. The largest values of the adhesive shear strength were identified in group 2 (the All bond universal adhesive system) and group 4 (the Icon etch), i.e. the approaches which contained MDP polymer. Overall, the results of our experimental study allowed considering the combined usage of the Icon infiltrant and the low-modulus composite material as a promising strategy in a routine dental clinical practice.

Fluorine in surface and suprapermafrost waters in Central Yakutia

Fluorine in surface and suprapermafrost waters in Central Yakutia

Stabilization of fluorine-contaminated soil in aluminum smelting site with biochar loaded iron-lanthanide and aluminum-lanthanide bimetallic materials

Trivalent metals-modified-biochar (BC) has been widely used for the removal of fluorine (F) in water, but little is known about its effects on the stability and mobility of F-contaminated soil. Two types of modified-BC materials (BC-loaded iron-lanthanide (BC/Fe-La) and BC-loaded aluminum-lanthanide (BC/Al-La)) were synthesized and used for the remediation of F-contaminated soil. The forms of BC/LaxFe3x(OH)y in BC/Fe-La and BC/LaxAl3x(OH)y in BC/Al-La were identified by spectroscopy, X-ray dispersion, thermogravimetric, and pore diameter/volume analyses. Following application (4–12%, w/w) to F-contaminated soil for 30 d, water soluble fluoride (WSF) decreased significantly. The modified-BC with a 1:1:1 molar ratio (BC: Al3+ or Fe3+: La3+) were more effective than those at 1:0.5:0.5. The BC/Al-La were the most effective to stabilize F. In particular, the highest decrease in WSF (by 91.75%) was obtained with the application of 12% BC/Al-La-2, while 8% BC/Al-La-2% and 12% BC/Al-La-1 reduced the WSF by 87.58% and 90.17%, respectively; all values obtained were lower than the national standard of China (< 1.5 mg/L). In addition, the sequential extraction results showed that modified-BC promoted the transformation of the other chemical speciation to the Fe/Mn-F.