Impact of acid-base conditions on defluoridation by induced crystallization

Publication date: 25 March 2020Source: Journal of Industrial and Engineering Chemistry, Volume 83Author(s): Linyu Deng, Ying Wang, Jianqi Zhou, Tinglin Huang, Xin SunAbstractDefluoridation by induced crystallization under extreme pH and bicarbonate/carbonate alkalinity of an aquatic environment was researched. At the conditions of initial pH 4–10 and alkalinity of less than 9.92 mM, the F− could be successfully removed by the induced crystallization of Ca5(PO4)3F on the PR surface within 1 h. With a prolonged time of 144 h, the F− could be also removed by the formation of Ca5(PO4)3F at initial pH 2 and alkalinity 9.92 mM. However, in extreme base aquatic environments, such as pH 12 or alkalinity 17.12 mM, the F− was partially removed by the induced crystallization of FCO3-apatite (Ca9.316Na0.36Mg0.144(PO4)4.8(CO3)1.2F2.48) and the F− could be completely removed by adjusting pH to a range of 4–10. Additionally, the safe disposal of spent crystal seed is successfully achieved as an extra benefit.Graphical abstract

Source: Journal of Industrial and Engineering Chemistry - January 27, 2020 Category: Chemistry Source Type: research