Amount Of Fluoride Research Articles

Spectrophotometric Fluoride Determination Using St. John's Wort Extract as a Green Chromogenic Complexant for Al(III).

In this study, we applied an innovative approach of green analytical chemistry to develop a novel and eco-friendly chromogenic agent for fluoride determination by making use of the nontoxic Al(III)-flavonoid complex in a natural extract from St. John's wort plant. The initial intensely yellow-colored Al(III)-flavonoid complex formed in the plant extract was converted to a colorless AlF6 3- complex with increasing amounts of fluoride, and color bleaching of the Al-flavonoid chromophore (measured as absorbance decrement) was proportional to fluoride concentration. The developed method gave a linear response within the F- concentration range of 0.11-1.32 mM with the LOD and LOQ values of 0.026 mM (0.5 mg L-1) and 0.079 mM (1.5 mg L-1), respectively. The LOD value for fluoride was below the WHO-permissible limit (1.5 mg L-1) and the US-EPA-enforceable limit (4 mg L-1) in water. The possible interference effects of common anions (Cl-, Br-, I-, NO3 -, HCO3 -, SO4 2-, and PO4 3-) and cations (K+, NH4 +, Ag+, Ca2+, Mg2+, Mn2+, Fe2+, and Fe3+) were investigated; the observed interferences from Fe2+, Fe3+, and PO4 3- were easily eliminated by masking iron with the necessary amount of Na2EDTA without affecting the blank absorbance of the Al(III)-flavonoid complex, precipitating phosphate with Ag(I) salt, and partly neutralizing alkaline water samples to pH 4 with acetic acid. The developed method was applied to real water samples and also validated against a reference spectroscopic method at the 95% confidence level.

CO2 conversion to formamide using a fluoride catalyst and metallic silicon as a reducing agent

Metallic silicon could be an inexpensive, alternative reducing agent for CO2 functionalization compared to conventionally used hydrogen or hydrosilanes. Here, metallic silicon recovered from solar panel production is used as a reducing agent for formamide synthesis. Various amines are converted to their corresponding amides with CO2 and H2O via an Si-H intermediate species in the presence of a catalytic amount of tetrabutylammonium fluoride. The reaction system exhibits a wide substrate scope for formamide synthesis. Spectroscopic analysis, including in situ Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), N2 adsorption/desorption analyses, and isotopic experiments reveal that the fluoride catalyst effectively oxidizes Si atoms on both surface and interior of the powdered silicon particles. The solid recovered after catalysis contained mesopores with a high surface area. This unique behavior of the fluoride catalyst in the presence of metallic silicon may be extendable to other reductive reactions, including those with complex substrates. Therefore, this study presents a potential strategy for the efficient utilization of abundant resources.

PSAT193 Skeletal Fluorosis due to Inhalant Abuse

Abstract Introduction Skeletal fluorosis (SF) is a rare toxic osteopathy characterized by massive bone fixation of fluoride. It is prevalent in India, China, and Africa due to fluoride water contamination, high consumption of brick tea, or even fluoride air pollution in industrialized areas. In the United States, it does not constitute a public health issue; however, it has been found recently in individuals who inhale high amounts of recreational fluoride. The mechanism of fluoride toxicity on the bone is attributed to its anabolic effect, and patients usually present with diffuse and chronic bone pain, non-vertebral fractures, and hyperparathyroidism. Case We present the case of a 39-year-old woman, who presented with bone pain and joint stiffness leading to impaired gait. She was previously seen by neurology, rheumatology, and oncology due to concern for neuropathy, rheumatoid arthritis, or possible occult malignancy but was referred after an inconclusive workup. Her past medical history was significant for a motor vehicle accident resulting in chronic back pain. She began using painkillers, but eventually, she turned to inhalants to help with pain management and depressive symptoms. Her inhalant of choice was keyboard cleaner. Slowly, she began noticing diffuse bone pain, muscle weakness, and difficulty walking that required her to use crutches. She continued to abuse inhalants 2-4 cans per day for about 5 years until March 2021. Physical exam was relevant for multiple bony prominences bilaterally on the elbows and thoracic spine. She also had a diminished range of motion of her 4 limbs, being unable to fully extend arms or legs. Lab evaluation showed elevated alkaline phosphatase 971, normal AST/ALT, vitamin-D 52, normal serum calcium and PTH, elevated random urine fluoride 23 mg/L (<3.2), elevated osteocalcin 292ng/ml (<32), and elevated N-telopeptide 2283 BCE/mmol cr (<64). Upper extremity x-rays showed evidence of diffuse mature periosteal reaction involving the proximal humerus, radius, ulna, and metacarpals and prominent medial and lateral epicondylar enthesopathy consistent with fluorosis. Discussion Skeletal fluorosis should be suspected in patients at risk for fluoride inhalation. Occupational exposure including huffing was key in this case. Diagnosis was confirmed by the detection of excess fluoride in the blood and urine. Currently, the only accepted treatment is to stop further ingestion or inhalation of fluoride. The half-life of retained fluoride in the bone is about 7 years. Unfortunately, there is no antidote for SF. One theoretical therapy is teriparatide, which might accelerate bone turnover and release skeletal fluoride. Further research is needed to identify more treatment options for patients diagnosed with this condition as the substance abuse crisis worsens in many developed countries. This case also emphasizes the importance of a thorough history prior to undertaking costly, time-consuming medical workups. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.

Groundwater evaluation of northern Jazmourian (south Iran) for drinking, agriculture, and associated health risks of nitrate and fluoride contamination

To investigate groundwater quality in the north of Jazmourian (Roudbar plain), 30 samples were collected and analyzed for evaluating drinking and irrigation status and associated health risks. In addition to major anions and cations, the fluoride and nitrate content of samples were analyzed using standard procedures. Nitrate levels range between 6.6 and 131 mg/L and exceed the WHO permissible limit in more than 23% and 80% of samples for adults and children, respectively. Fluoride amounts ranged from 0.4 to 4.8 mg/L in samples. The F- level exceeded the WHO standard limit in 10% of samples. The EC level increases in fine-grained deltaic deposits toward the south. The concentrations of major ions (HCO3, Cl, SO4, Mg, Na, K) increase southwards, following the flow direction. There are, however, lateral (east-west) differences in water quality due to the influence of such factors as the rate of recharge and the type of bedrock. Wherever the redbeds comprise the bedrock and the recharge rate is weaker, the dissolved salts are higher in amount. The water quality index (IWQ) indicated that 13, 13, and 4 samples are in “good,” “poor,” and “very poor” quality classes, respectively. By using the irrigation water quality index (IWQI), eight samples were at “low restriction,” nine samples at “moderate restriction,” twelve samples at “high restriction,” and one sample at “severe restriction” classes. The acquired findings revealed that the mean oral hazard quotient of nitrate was 1.14, 1.0, and 0.84, and for fluoride, it was 0.82, 0.72, and 0.61 for children, females, and males, respectively. The total hazard index for cumulative NO3 - and F- toxicity exceeded the acceptable level in 76.67%, 66.67%, and 56.67% of samples for children, females, and males, respectively.

Comprehensive assessment of water quality and associated health risks in an arid region in south Iran

This study aims at investigating the quality of drinking water and evaluating the non-carcinogenic risk of fluoride and nitrate ions in drinking water, and fluoride in tea in Zarrin Dasht, Iran. We focus on tea since it is the most popular drink among Iranian people and in the study region. We collected and analyzed 23 drinking water samples and 23 tea samples from different locations in the study region. Based on the water quality index, the consumed drinking water does not have a good quality in most Zarrin Dasht areas. Accordingly, the water quality index (WQI) is poor and very poor in 70% and 13% of the water samples, respectively. The average fluoride concentration of the tea samples is 2.71 mg/L. The mean values of Fluoride Hazard Index (HIfluoride) are 3.77, 2.77, and 2.33 for children, teenagers, and adults, respectively, which are higher than the safe limit of 1. The Nitrate Hazard Index (HInitrate) is higher than the safe limit of 1 in 8.7% of the samples. The results of the Monte Carlo simulation demonstrate that HIfluoride and HInitrate are higher than 1 in all the groups, except for adults. According to the results of the sensitivity analysis, ingestion rate and body weight have a large effect on HIfluoride and HInitrate, but body weight is inversely associated with sensitivity. According to the Piper diagram, saline water is the predominant type in Zarrin Dasht. Besides, the results of the principal component analysis (PCA) show a high correlation between fluoride and pH, which could be related to the effect of pH on fluoride dissolution and ion exchange. Therefore, appropriate measures are recommended to be taken in order to reduce the amount of fluoride in the drinking water resources of this region. Reduction of tea consumption can also be considered an important factor in decreasing the amount of fluoride intake.

Application of bottom ash from cattle manure combustion for removing fluoride and inactivating pathogenic bacteria in wastewater

This study addressed the utilization of bottom ash derived from the combustion of cattle manure (BA-CM) for removing fluoride from industrial wastewater and killing gram-negative (E. coli O157:H7 and S. typhimurium) and gram-positive pathogenic bacteria (L. monocytogenes), and it will ensure both the disposal of solid waste and the purification of water. BA-CM had a pore size corresponding to mesopores (2–50 nm) and a fractal dimension (D) of 2.88. The main elements constituting the BA-CM were calcium (Ca) in the form of Ca5(PO4)3(OH) and CaCO3. The Ca released from BA-CM was helpful for removing fluoride via the formation of CaF2. The fluoride adsorption by BA-CM approached equilibrium after 6 h. The fluoride equilibrium adsorption on to BA-CM was well fitted to the Langmuir model and was calculated to have a maximum adsorption capacity of 112.07 mg/g. At pH 3, the adsorption amount of fluoride was 76.33 mg/g, and as the pH increased to 7, fluoride adsorption decreased to 50.74 mg/g. In the pH range of 7–11, the amount of fluoride adsorbed did not decrease and was maintained (50.53 ± 0.22 mg/g). More than 97% fluoride removal could be achieved using 13.33 g/L of BA-CM. BA-CM treatment effectively inactivated pathogens in the contaminated water. The BA-CM treatment for 4 min achieved 3.77 log CFU/mL and 6.56 log CFU/mL reductions in E. coli O157:H7 and S. typhimurium, respectively. L. monocytogenes exhibited higher resistance to BA-CM than the other pathogens tested, and 30 min was required to achieve a reduction of 6.33 log CFU/mL. BA-CM, obtained from the combustion of cattle manure for energy production, can be used as a value-added material for removing fluoride and disinfecting water contaminated with pathogenic bacteria.

Clinical Prospective Assessment of Genotoxic and Cytotoxic Effects of Fluoride Toothpaste and Mouthwash in Buccal Mucosal Cells.

Background: Fluorides are an essential component of oral hygiene products used to prevent dental decay. Therefore, a question arises about the potential harms of joint use of fluoridated toothpaste and mouthwashes regarding the increased amount of fluoride in the oral mucosa. Methods: This prospective, double-blinded parallel randomized clinical trial was conducted using a buccal micronucleus cytome assay (BMCyt assay). Forty-one participants were randomly assigned to the two groups. All participants used the same kinds of toothpaste for 12 weeks, designed explicitly for this study (non-fluoride, 1050 ppm F, and 1450 ppm F each for 4 weeks). Simultaneously, during the 3 months of the research, one group used mouthwash with fluoride (450 ppm) and another without fluoride. The buccal mucosal sampling was taken before using the tested products and after 4, 8, and 12 weeks of their use. Results: The frequency of micronuclei and the majority of other scored endpoints from the BMCyt assay showed no statistically significant differences within and between the studied groups. Comparing two groups, only statistically significant increases in the number of cells with nuclear buds (p = 0.048) and karyorrhexis (p = 0.020) at four weeks of usage were observed in the group that used mouthwash with fluoride. Conclusion: On the basis of the results, it can be concluded that simultaneous application of fluoridated toothpaste and fluoride mouthwash does not lead to cytogenetic damage in buccal mucosal cells.

Remineralization activities of toothpastes with and without aloe vera with different ratios of fluoride on demineralized enamel: An In-vitro study.

The aim of this in-vitro study was to evaluate and compare the efficacy of both pure aloe vera and commercially available toothpastes with different fluoride compounds and different fluoride amounts on artificial initial enamel lesions by Vicker's microhardness values. In the study, 72 extracted human molar teeth were divided into mesiodistal and 144 specimens were prepared using the vestibule and palatal/lingual surfaces of the teeth. After the surface treatments and initial microhardness measurements, all the specimens were placed in a demineralizing solution (pH: 4.5) for 7 days, resulting in artificial initial enamel lesion, and were randomly assigned to eight groups (n = 18). After the teeth were subjected to pH cycle for 14 days, microhardness measurements were repeated and the data were recorded. Statistical analyzes were performed using MedCalc Statistical Software version 12.7.7. The significance level was determined to be 0.05. In the statistical results, when the microhardness values after demineralization and post-cycle were compared, Groups B1 and A2 showed the lowest values, while Groups A3 and B3 did not show a significant difference in terms of microhardness values after demineralization and post-cycle, and only Group B4 showed statistically significantly higher values. This study emphasized the remineralization effects of fluoride on initial enamel lesions. It can be said that toothpaste containing 1450 ppm fluoride and aloe vera provides an effective remineralization and sodium monofluorophosphate formulation may have a synergistic effect with aloe vera.

Evaluation of Fluoride Concentration in Drinking Water of Some Cities within Anbar Province, Iraq

A fluoride atom (F) has a negatively-charged ion called a fluoride ion. The element fluoride can also be found in a compound called fluoride. Many countries with high rates of dental fluorosis naturally contain high levels of fluoride in their minerals and water supplies. The fluoride ion concentrations were determined by collecting drinking water samples twice a month from (July/2020 - to June/2021) from 4 main cities in Anbar Province in Iraq, during the rainy and dry seasons. The fluoride concentrations were then analyzed and compared with standard guides of the United States Environmental Protection Agency (USEPA) and the World Health Organization (WHO). The objective of this study is to evaluate the fluoride concentrations in Ramadi, Fallujah, Khalidiyah, and Heet cities. The results showed small variations ranging from (0.041 mg/l) to (0.051 mg/l) when these results are compared with Environmental Protection Agency (EPA) and World Health Organization (WHO) standard limitations. the recommended standard limitations of (EPA) and (WHO) for fluoride concentration range from (0.4 - to 1.5) mg/l, therefore the drinking water of these cities is comfortable to drink, but it may cause some problems, such as dental caries, dental fluorosis, colorless teeth yellowish, and blackish teeth. The results are also less than the typical concentration limitations, which, is (0.7 mg/l). To avoid the danger of poisoning, adding fluoride to water is not recommended unless it has been recommended by a professional in the food system or a dentist. However, humans can also get fluoride from sources other than water, and the quantity of fluoride they consume is different from one person to another.

Analysis of the fluoride levels of well water and tea consumed by the Moroccan population in different rural areas

Fluoride plays a fundamental part in human health. However, continued ingestion of excessive fluoride may cause significant negative health effects on people, ranging from mild dental fluorosis to crippling skeletal fluorosis, depending on the level and time of exposure to fluorides. In provincial areas, the presence of fluoride in well water may be due to natural factors or human activities.The reason for our work was to evaluate the level of tainting of groundwater by fluorides from various areas in Morocco situated in rural and agricultural areas, where the main wellspring of consumable water is well water, and the reasons for fluorosis in this area. The 44 samples were taken in seven Moroccan regions: Had Soualem-Berrechid, Kenitra, Fez, Tit Mellil, Sidi Slimane-Sidi Kacem-Zirara, Larache, and Brachoua, and 12 samples of tea were taken from different souks and commercials in Morocco.Fluoride dosing measurements in well water were performed using the potentiometric technique using the fluoride-specific ion electrode (HI-4110) at room temperature, while the determination of fluorine in tea is done by the spectrophotometric method.The results of fluoride levels revealed in different well waters from different regions range from 0.2 to 6.58 mg/l. For the green and black tea samples, the fluorine content varies between 0.48 and 1.60 mg/l for the 10 min infusion and between 0.93 and 2.7 mg/l for the 30 min infusion. These results make it possible to warn the population facing the risk of developing dental fluorosis by limiting the amount of fluoride ingested by the consumed foods.

Tailored design of a novel composite foam of sodium alginate used for fluoride ion removal.

Fluoride is an essential micronutrient for humans. Nonetheless, when the amount of fluoride ion is greater than required, it will cause skeletal fluorosis and dental fluorosis to threaten human health. In this paper, a series of sodium alginate (SA)-based foam materials are prepared by freeze-drying technique and anchored with the nano-activated alumina (nAl2O3) in the SA to obtain a novel adsorbent of SA-nAl2O3 foam used for fluoride ions removal. The SA-nAl2O3 foam morphology was further explored and confirmed that nAl2O3 existed stably in the SA. The adsorption results showed that the maximal fluoride ion adsorption capacity was 5.09 mg/g with 20 mg/L fluorine solutions at a pH of 3. The adsorption isotherm fitted adequately to the Langmuir isotherm model, which demonstrated that the adsorption process is closer to monolayer adsorption. The adsorption kinetics behavior of SA-nAl2O3 foam was described by a pseudo-second-order model, and the adsorption process occurred by chemisorption. Adsorption thermodynamics analysis emphasized that the adsorption process was spontaneous and endothermic. The main mechanism of the foam is ion exchange. The SA-nAl2O3 foam exhibited excellent regeneration performance and stability after three cycles.

Hydrometallurgical stepwise separation of alumina and recovery of aluminum fluoride from waste anode cover material of aluminum electrolysis

Anode cover material holds marked importance owing to its effect of maintaining the thermal balance of aluminum reduction cells, and is categorized as solid waste because of its continuous accumulation. However, cover materials contain large amounts of alumina and fluoride; thus, can be considered for strategic resource recovery. This research has developed a process for separating alumina and recovering aluminum fluoride from anode cover materials by aluminum salt solution leaching. In the present work, the effects of different factors on the leaching behaviors of sodium and fluoride during aluminum salt solution leaching were investigated. The results showed that 98.1 % sodium and 95.1 % fluoride were extracted when the Al3+ concentration was 2.5 mol/L, the liquid to solid ratio was 20 mL/g, and the stirring speed was 300 rpm at 90 °C for 2 h. Aluminum and fluoride were then precipitated as aluminum hydroxyfluoride hydrate (AHF) from the leachate. The aluminum fluoride (AlF3) product with high purity was obtained by calcining AHF precipitation, and the average particle size was 66.1 μm. This work demonstrates significant application potential on green recycling of anode cover materials and realize a high-value utilization of aluminum and fluoride resources. This plays a crucial role in the life cycle assessment (LCA) of the anode cover material.

Al2O3/Fe3O4/ZrO2 ternary oxide sorbent: Synthesis, characterization and sorption behavior to fluoride and phosphate ions from aqueous solution

ABSTRACT. Excess quantities of fluoride and phosphate in water bodies can lead to fluorosis and eutrophication problems, respectively. In search of a promising adsorbent targeting these ions, Fe3O4/Al2O3/ZrO2 ternary oxide was synthesized via co-precipitation method and characterized by X-ray diffraction (XRD), Fourier transform-infrared (FTIR) and Brunauer-Emmer-Teller (BET). Its specific surface area was found to be 205 m2/g. The effects of solution pH, adsorbent dose, contact time, agitation speed and initial fluoride and phosphate concentrations were also investigated and the optimum values were 4, 0.5 g, 12 h, 100 rpm and 20 mg/L, respectively, for fluoride and 5, 0.1 g, 8 h, 100 rpm and 10 mg/L, respectively, for phosphate. Fluoride and phosphate adsorptions fitted well with Freundlich and Langmuir isotherm models, respectively and their kinetic data correlated well with the pseudo-second order model. Desorbability study revealed that maximum desorption was achieved at pH 12. Thermodynamics study on the other hand showed that adsorption of fluoride was nonspontaneous and endothermic whereas that of phosphate was spontaneous and exothermic. Application on real water sample decreased the concentration of fluoride from 4.92 to 1.97 mg/L in ground water and phosphate from 1.7 to 0.35 mg/L lake water showing its potential as a promising adsorbent.
 
 KEY WORDS: Adsorption, Fluoride, Phosphate, Ternary oxide sorbent, Isotherm models
 
 Bull. Chem. Soc. Ethiop. 2022, 36(3), 555-569. 
 DOI: https://dx.doi.org/10.4314/bcse.v36i3.6 

Camellia sinensis Chloroplast Fluoride Efflux Gene CsABCB9 Is Involved in the Fluoride Tolerance Mechanism.

Soil is a main source of fluoride for plants. The tea plants (Camellia sinensis) accumulate excessive amounts of fluoride in their leaves compared to other plants, but their fluoride tolerance mechanism is poorly understood. A chloroplast fluoride efflux gene (CsABCB9) was newly discovered by using transcriptome analysis, cloned from Camellia sinensis, and its function was demonstrated in the fluoride detoxication mechanism in Escherichia coli/Xenopus laevis oocytes and Arabidopsis thaliana. CsABCB9 is expressed in tea leaves upon F− treatment. The growth of tea, E. coli, and Arabidopsis were inhibited by F− treatment. However, growth of CsABCB9-overexpression in E. coli was shown to increase with lower fluoride content under F− treatment compared to the control. Furthermore, chlorophyll, xanthophyll and soluble sugar contents of CsABCB9-overexpression in Arabidopsis were improved under F− treatment compared to the wild type. CsABCB9 functions in fluoride transport, and the mechanism by which CsABCB9 improves fluoride resistance in tea is mainly chloroplast protection through fluoride efflux.

Evaluation of Fluoride Release in Chitosan-Modified Glass Ionomer Cements

ObjectiveThis study assessed the influence of chitosan nanoparticles on the fluoride-releasing ability of 4 glass ionomer cement (GIC) through an in vitro analysis. MethodsFour types of GIC (type II light cure universal restorative, type II universal restorative, GC Fuji VII, and type IX) were modified with nanochitosan particles; 10% chitosan was added to the glass ionomer liquid. Six specimens for each of the 4 groups were created, using expendable Teflon moulds. Discs of each type of GIC (n = 6) were immersed in deionised water at various time intervals. Electrodes selective for fluoride ions were employed to analyse the amount of released fluoride at 1, 7, 14, 21, and 28 days. ResultsChitosan-modified GICs showed greater fluoride release than conventional GICs at all time points. All samples showed an initial high release of fluoride that tapered off with time. The total amount of fluoride released increased from the 1st day to the 28th day on adding chitosan to all the 4 types of GIC. Amongst those, type IX high-strength posterior extra with chitosan released a considerably higher quantity of fluoride at all time intervals. ConclusionsIn all the experimental groups, adding chitosan to the glass ionomer liquid had an accelerating effect on its fluoride-releasing property.

Determination of fluoride content in teas and herbal products popular in Poland.

Fluoride level, due to its narrow therapeutical range, must be constantly monitored in beverages, especially in daily-consumed plant infusions. Fluoride is important for prevention of tooth decay and osteoporosis, but its excess leads to fluorosis. Since tea can selectively absorb fluorides from soils, the question arises if a long-term consumption can pose an adverse effect on human health. Infusions of 33 popular teas (black, green, white, earl grey, pu-erh), tea-like products (rooibos, yerba mate) and herbs (chamomile, mint, nettle, purges, yarrow) available in the Polish market were analyzed with respect to a fluoride level by means of a validated ion-selective electrode method, which is proven to be fast and reliable. Significantly different fluoride concentrations in infusions were observed, with black tea on top, where extraction of fluoride is the highest (average 2.65mg F-/L, range 0.718-6.029mg/L). Two-fold higher fluoride contents were measured in infusions made from black tea bags than from leaves (average 3.398mg/L and 1.529mg/L, respectively). Green teas released comparable amounts of fluoride as black teas, while in herbal extracts the fluoride content was negligible. The rank with respect to the fluoride concentration in an infusion is as follows: black tea > green tea > earl grey > pu-erh > white tea>>>rooibos, yerba mate, herbal products. Increasing of brewing time results in an increased fluoride content, but the overall content of fluoride in the analyzed infusions of teas and herbs was not high enough to cause a risk of fluorosis, even if left to brew up to 15min.

Deterministic and probabilistic human health risk assessment for fluorides in drinking groundwater from Lukavac, Bosnia and Herzegovina.

Although fluorides are essential for dental health, there are growing health concerns regarding the risk-benefit ratio of fluoride exposure. The objectives of the study were to obtain data on the amount and human health risks of fluoride in drinking groundwater, as well as to compare and evaluate the differences in the outputs obtained by two different approaches in health risk assessment (deterministic vs probabilistic). From a densely populated industrial area of northeastern Bosnia and Herzegovina, a total of 54 groundwater samples were collected. Fluoride concentrations varied from 1.69 to 3.52 mg/L. The WHO’s threshold value for fluoride in drinking water was exceeded in all the samples analysed, indicating an increased daily intake of fluoride from groundwater. Deterministic and semi-probabilistic techniques were used for exposure assessment and health risk quantification. Generally, the deterministic approach resulted in acceptable health risks in most adult exposure scenarios. However, the Monte Carlo simulation revealed that 20.6, 20.8, and 99.8% of adult males, females, and children, respectively, were above the tolerable upper intake level, indicating that both adults and children face a significant health risk. Nevertheless, small children are more vulnerable to environmental hazards than youth and adults. Hence, a more in-depth risk-benefit analysis is required to reduce/or optimize fluoride content in drinking water to prevent tooth decay and fluorosis at all ages. Considering that optimal daily intake of fluorides is a crucial factor for preserving human health, decision-makers should take steps to emphasize the importance of continuous monitoring of fluoride concentrations in drinking water.

Effect of the Addition of Varying Concentrations of Silver Nanoparticles on the Fluoride Uptake and Recharge of Glass Ionomer Cement.

This study aimed to compare the amount of fluoride uptake and the recharge and release characteristics of conventional glass ionomer cement (GIC) without any additives in comparison to conventional glass ionomer cement supplemented with silver nanoparticles (AgNPs) at two concentrations: 0.1% and 0.2% (w/w). A total of 60 specimens were used in this in vitro study. The sample was divided into six groups—including three groups without fluoride charge: Group 1 (conventional GIC), Group 2 (GIC with 0.1% silver nanoparticles), and Group 3 (GIC with 0.2% silver nanoparticles; and three groups with fluoride charge: Group 4 (conventional GIC with fluoride); Group 5 (GIC with 0.1% silver nanoparticles with fluoride); Group 6 (GIC with 0.2% silver nanoparticles with fluoride), where Group 1 is considered the control group and the other five groups are used as the test groups. The amount of fluoride released was measured on days 1, 2, 7, 15, and 30. The comparisons were made between the groups with and without fluoride and among all the groups. A significant difference in the amount of fluoride released was observed between the groups, with the highest amount occurring in Group 1, followed by Group 2; the lowest amount of fluoride released was observed in Group 3 (p < 0.05). The groups with fluoride recharge (Groups 4, 5, and 6) exhibited a higher amount of fluoride release than the groups with no recharge (Groups 1, 2, and 3); however, Group 1 has more fluoride release compared to all other groups on days 1, 2, 7, 15, and 30 (p < 0.05). The amount of released fluoride decreased from day 1 to day 30 in all of the groups in the study. Despite the antimicrobial and anticariogenic benefits of adding silver nanoparticles to GIC, it seems that fluoride release characteristics are significantly affected by the addition of this material. This may force the clinician to a compromise between the antimicrobial benefit of silver nanoparticles and the remineralizing advantage of fluoride.

Pollutants’ migration and transformation behavior in phosphorus ore flotation tailings treated with different additives

Dolomite and fluorapatite are the most common minerals found in phosphorus ore flotation tailings (PTs). The migration and transformation behavior of large amounts of soluble impurities phosphorus (P), fluoride (F) and heavy metals (Mn, Cr, Pb) in PTs were studied. The solidification/leaching mechanism of pollutants in PTs treated with nine materials, namely nitrate sulfur gypsum (NG), phosphogypsum (PG), desulfurization gypsum (FGD), polyaluminium chloride (PAC), hydroxyapatite (HAP), humic acid (HA), MgO, FeSO4, CaCl2, was respectively simulated and investigated through the PHREEQC by using solid-solid phase reaction. 2.25 wt% PAC or 1.00 wt% FeSO4 treatment of PTs due to the favorable polymerization capabilities of P and F stabilization efficiency were 83.70% and 77.66%, MgO treatment also showed obvious stabilization/solidification effect on P, F and heavy metals. The migration and transformation behaviors of pollutants in PTs were primarily influenced by the concentrations of Ca2+ and Mg2+, as well as Fe3+/Fe2+ ratio and acid-base conditions. Dissolution-precipitation, reduction-oxidation, and adsorption-complexation were the key mechanisms of pollutants’ behavior, and these processes are controlled by the moisture content and particle size distribution of PTs. The stabilization/solidification system, featuring in simple solid-solid phase reaction conditions and multi-waste synergistic treatment provides the possibility of further harmless treatment and resource utilization of PTs.

Investigation of Water-Soluble Binders for LiNi0.5 Mn1.5 O4 -Based Full Cells.

Two water‐soluble binders of carboxymethyl cellulose (CMC) and sodium alginate (SA) have been studied in comparison with N‐methylpyrrolidone‐soluble poly(vinylidene difluoride–co‐hexafluoropropylene) (PVdF‐HFP) to understand their effect on the electrochemical performance of a high‐voltage lithium nickel manganese oxide (LNMO) cathode. The electrochemical performance has been investigated in full cells using a Li4Ti5O12 (LTO) anode. At room temperature, LNMO cathodes prepared with aqueous binders provided a similar electrochemical performance as those prepared with PVdF‐HFP. However, at 55 °C, the full cells containing LNMO with the aqueous binders showed higher cycling stability. The results are supported by intermittent current interruption resistance measurements, wherein the electrodes with SA showed lower resistance. The surface layer formed on the electrodes after cycling has been characterized by X‐ray photoelectron spectroscopy. The amount of transition metal dissolutions was comparable for all three cells. However, the amount of hydrogen fluoride (HF) content in the electrolyte cycled at 55 °C is lower in the cell with the SA binder. These results suggest that use of water‐soluble binders could provide a practical and more sustainable alternative to PVdF‐based binders for the fabrication of LNMO electrodes.