scholarly journals Fluoride removal from natural waters by polymer inclusion membranes

2021 ◽  
pp. 120161
Author(s):  
Berta Alcalde ◽  
Enriqueta Anticó ◽  
Clàudia Fontàs
Keyword(s):  
Natural Waters ◽  
Fluoride Removal

scholarly journals Defluoridation of synthetic and natural waters by polyaluminum chloride-chitosan (PACl-Ch) composite coagulant

2017 ◽  
Vol 18 (1) ◽  
pp. 259-269 ◽  
Author(s):  
Mehrnoosh Abtahi ◽  
Ali Koolivand ◽  
Sina Dobaradaran ◽  
Kamyar Yaghmaeian ◽  
Anoushiravan Mohseni-Bandpei ◽  
...  
Keyword(s):  
Natural Waters ◽  
High Efficiency ◽  
Operating Conditions ◽  
Fluoride Removal ◽  
Optimum Conditions ◽  
Polyaluminum Chloride ◽  
Residual Level ◽  
Wide Range ◽  
High Concentrations ◽  
Composite Coagulant

Abstract Removal of fluoride from drinking water by polyaluminum chloride-chitosan (PACl-Ch) composite coagulant was studied in a batch system. Two types of PACl-Ch coagulant were synthetized as PACl-Ch I and PACl-Ch II with chitosan to aluminum (Ch:Al) weight ratios of 0.5 and 1.0, respectively, and were used for defluoridation under different operating conditions. The composite coagulants were found to be more efficient than both PACl and chitosan. By an increase in the Ch:Al ratio from 0.5 to 1.0, the composite coagulant provided a little more efficiency of fluoride removal and lower residual level of Al. The optimum conditions of pH for fluoride removal by PACl-Ch I and PACl-Ch II were 8.0 and 7.5, respectively. Fluoride removal by the coagulants was not significantly affected by natural organic matter and turbidity, but was declined by high concentrations of common ions. To achieve desirable fluoride levels (lower than 1.0 mg/L) for natural water samples with fluoride levels of 2.0–2.9 mg/L, the required dosage of the composite coagulants were determined to be as low as 3–5 mgAl/L. The PACl-Ch coagulants demonstrated high efficiency for fluoride removal as well as low Al residual level (mainly lower than 0.2 mg/L) in a wide range of operating conditions.

THE MECHANISM OF NITRATES TRANSFORMATION IN THE PROCESSES OF ELECTROCHEMICAL TREATMENT OF NATURAL WATERS

2002 ◽  
Vol 1 (3) ◽  
pp. 341-346
Author(s):  
Viorica Iambartev ◽  
Gheorghe Duca ◽  
Maria Gonta ◽  
Vera Matveevici
Keyword(s):  
Natural Waters ◽  
Electrochemical Treatment

DISTRIBUTION OF DISSOLVED METHANE IN SURFACE COASTAL WATERS OF THE NORTHEASTERN PART OF THE BLACK SEA

2017 ◽  
Author(s):  
Elena Kovaleva ◽  
Elena Kovaleva ◽  
Alexander Izhitskiy ◽  
Alexander Izhitskiy ◽  
Alexander Egorov ◽  
...  
Keyword(s):  
Black Sea ◽  
Natural Waters ◽  
Sea Water ◽  
The Black Sea ◽  
Methane Formation ◽  
Anthropogenic Pressure ◽  
Russian Science ◽  
Southeastern Part ◽  
Dissolved Methane ◽  
Continental Runoff

Studying of methane formation and distribution in natural waters is important for understanding of biogeochemical processes of carbon cycle, searching for oil and gas sections and evaluation of CH4 emissions for investigations of greenhouse effect. The Black Sea is the largest methane water body on our planet. However, relatively low values of methane concentration (closed to equilibrium with the atmospheric air) are typical of the upper aerobic layer. At the same time, the distribution pattern of CH4 in surface waters of coastal areas is complicated by the influence of coastal biological productivity, continental runoff, bottom sources, hydrodynamic processes and anthropogenic effect. The investigation is focused on the spatial variability of dissolved methane in the surface layer of the sea in coastal regions affected by the continental runoff and anthropogenic pressure. Unique in situ data on methane concentrations were collected along the ship track on 2 sections between Sochi and Gelendzhik (2013, 2014) and 2 sections between Gelendzhik and Feodosia (2015). Overall 170 samples were obtained. Gas-chromatographic analysis of the samples revealed increase of CH4 saturation in the southeastern part of the Crimean shelf and the Kerch Strait area. Such a pattern was apparently caused by the influence of the Azov Sea water spread westward along the Crimean shore from the strait. This work was supported by the Russian Science Foundation, Project 14-50-00095 and the Russian Foundation for Basic Research, Project 16-35-00156 mol_a.

Diseases Prevention by Water Defluoridation Using Hydrotalcites as Decontaminant Materials

2017 ◽  
Vol 68 (1) ◽  
pp. 168-171 ◽  
Author(s):  
Letitia Doina Duceac ◽  
Cristina Elena Dobre ◽  
Ioana Pavaleanu ◽  
Gabriela Calin ◽  
Simona Nichitus ◽  
...  
Keyword(s):  
Dental Fluorosis ◽  
Precipitation Method ◽  
Original Structure ◽  
Fluoride Removal ◽  
Major Goal ◽  
Bone Stiffness ◽  
Morphological Aspects ◽  
Adsorption Capacities ◽  
Interlayer Structure ◽  
Co Precipitation

Preventing diseases is deemed to be the major goal of our century especially when an excessive fluoride in drinking water can cause dental fluorosis, bone stiffness, rheumatism and skeletal fluorosis. Fluoride uptake from groundwater implies a worldwide multidisciplinary effort in order to develop renewable, cheap, human friendly materials. Among other materials, hydrotalcites could be good candidates for an efficient fluoride removal from water due to their adsorption, anion exchange and reconstruction properties. These nanostructured materials were synthesized using co-precipitation method in controlled conditions. Presence of anions in the interlayer structure and morphological aspects were performed by FTIR and SEM techniques. Thermal treatment of hydrotalcites showed good adsorption capacities for water defluoridation mostly due to their tendency to restore the original structure.

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