Chemistry of Fluoride Leaching and Associating Influential Factors in Plaster Board Waste

Plaster board waste generated from industries, usually contains major proportion of calcium as calcium sulfate. In addition, fluoride is remarkably one among the constituents of this waste material. Experimental studies were conducted to determine the fluoride leaching as a function of particle size, pH of leaching solvent (distilled water) and water: PBP ratio. The influence of sodium salts on the leaching of fluoride from PBP was studied. It was explored that one gram of plaster board waste contains 18.54 mg F per gram of PBP. High leaching of 3.70 mg F per liter was studied at pH 6.02 with Ca2+ and TDS contents of 1050 mg L-1 and 1640 mg L-1 respectively. The influence of fluoride leaching by sodium phosphate recorded a high value of 12.75 mg L-1 with no detectable amount of calcium ions. The leaching mechanism was predicted significantly by the exchange of Na+ and Ca2+ ions. The leaching rate as a consequence of shaking and stirring dynamics was also investigated at different conditions

Groundwater fluoride removal using modified mesoporous dung carbon and the impact of hydrogen-carbonate in borehole samples

International audienceThere have been many research reports pertained to the interference of co - ions including hydrogen carbonate against the removal of fluoride from water. In this context, the present research explores the fluoride removal efficiency of ammonium carbonate modified dung derived carbon (DDC500) in the absence and presence of hydrogen carbonate using synthetically made fluoride solutions and groundwater samples. The adsorbent DDC500 was found to achieve the highest removal of 80% of fluoride at pH 6.95 than the washed carbon (DDC500W) and dung ash (DA) of 48% and 23% respectively. In DDC500, the carbon base in concert with inorganic residues actively functioned in the fluoride removal process and chosen for synthetic fluoride solutions (2-5 mg L) and 16 groundwater samples (2.1-3.6 mg L) from 10 locations of Usilampatti Taluk in Madurai District, South India. After the removal of hydrogen carbonate in groundwater, the percentage of samples was increased in accordance with the safe limits of World Health Organization (WHO) and Bureau of Indian Standard (BIS). Langmuir isotherm model (R = 0.9379) was in concordance with the adsorption of fluoride from groundwater free from hydrogen carbonate. The dynamics of other groundwater quality parameters at conditions and the independency between F-/HCO- ratio and DE were illustrated by scatter plots. Characterization studies for the dried dung (CD110), derived carbons (DDC500 and DDC500W) and ashes (CD110A, DDC500A and DDC500WA) using FE-SEM, XRD, FTIR, Raman and TGA - EGA were done to understand the nature and behavior of materials

Spatiotemporal distribution, trend, forecast, and influencing factors of transboundary and local air pollutants in Nagasaki Prefecture, Japan

Abstract The study of PM2.5 and NO2 has been emphasized in recent years due to their adverse effects on public health. To better understand these pollutants, many studies have researched the spatiotemporal distribution, trend, forecast, or influencing factors of these pollutants. However, rarely studies have combined these to generate a more holistic understanding that can be used to assess air pollution and implement more effective strategies. In this study, we analyze the spatiotemporal distribution, trend, forecast, and factors influencing PM2.5 and NO2 in Nagasaki Prefecture by using ordinary kriging, pearson's correlation, random forest, mann–kendall, auto-regressive integrated moving average and error trend and seasonal models. The results indicated that PM2.5, due to its long-range transport properties, has a more substantial spatiotemporal variation and affects larger areas in comparison to NO2, which is a local pollutant. Despite tri-national efforts, local regulations and legislation have been effective in reducing NO2 concentration but less effective in reducing PM2.5. This multi-method approach provides a holistic understanding of PM2.5 and NO2 pollution in Nagasaki prefecture, which can aid in implementing more effective pollution management strategies. It can also be implemented in other regions where studies have only focused on one of the aspects of air pollution and where a holistic understanding of air pollution is lacking