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Electrochemical removal of fluoride ions from industrial wastewater

Authors Shen, Feng
Chen, Xueming
Gao, Ping View this author's profile
Chen, Guohua View this author's profile
Issue Date 2003
Source Chemical engineering science , v. 58, (3-6), 2003, FEB-MAR, p. 987-993
Summary Fluoride ions were removed electrochemically from a solution using a combined electrocoagulation and electroflotation process. For an influent fluoride concentration of 15 mg/l, a value after lime precipitation, the effluent fluoride concentration can be lower than 2 mg/l when the pH in the coagulation cell is around 6, charge loading is at 4.97 F/m(3) water, and the residence time is 20 min. Even lower effluent concentration can be achieved if 50 mg/l of Fe3+ or Mg2+ are added into the coagulation unit. The anions generally reduce the fluoride removal efficiency except Cl- whose corrosion pitting of the electrode can result in 130\% current efficiency. The composition of the sludge produced from the operation was analyzed using X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectroscope system (ToF-SIMS). The characterization results show that the defluorination is a chemical adsorption process with F- replacing the -OH group from the Al-n(OH)(3n) flocs. (C) 2003 Elsevier Science Ltd. All rights reserved.
ISSN 0009-2509
Language English
Format Article
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