Immobilization of fluoride in the sediment of mine drainage stream using loess, Northwest China

Remediation of soils contaminated with fluoride using seaweed-derived materials: case of slopes of mount Meru

“…If the soil contains calcareous properties fluoride leaching and dispersion will be limited by the formation of 𝐶𝑎𝐹 2 precipitate (Jha et al, 2011) whereas sodic soils are characterized by high soluble fluoride concentration due to the formation of a highly soluble 𝑁𝑎𝐹. Therefore, sandy soils contains lesser fluoride compared to clay soils, but if the sandy soil is sodic, it is likely to contain high fluoride concentration (Li et al, 2020). Apart from the soil properties and composition, fluoride concentration and release into the soil depends on other external factors such as weathering, climate, and altitude.…”

“…Fluoride bound to iron and manganese (Fe/Mn-F) is the fluoride fraction that is attached to either aluminum (𝐴𝑙 𝑋+ ), iron (𝐹𝑒 𝑋+ ), or Manganese (𝑀𝑛 2+ ) elements in the soil (Chen et al, 2013). Unlike the first two, the reaction of fluoride with these elements involves complex formation and dissociation and its amount is dependent on pH and the number of targeted cations present in the soil (Li et al, 2020;Yi et al, 2017). For example, low pH favors the formation of 𝐴𝑙 − 𝐹 or 𝐹𝑒 − 𝐹 complex however its concentration cannot exceed the concentration of these elements present in the soil.…”

“…For example, low pH favors the formation of 𝐴𝑙 − 𝐹 or 𝐹𝑒 − 𝐹 complex however its concentration cannot exceed the concentration of these elements present in the soil. minimization of the bioavailability of this fluoride fraction involves immobilization by the introduction of another stable element with a stronger affinity to fluoride (Li et al, 2020).…”