Abstract
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/m3water, 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 Aln(OH)3nflocs.
Original language | English |
---|---|
Pages (from-to) | 987-993 |
Number of pages | 7 |
Journal | Chemical Engineering Science |
Volume | 58 |
Issue number | 3-6 |
DOIs | |
Publication status | Published - 1 Jan 2003 |
Externally published | Yes |
Keywords
- Adsorption
- Electrocoagulation
- Environment
- Flotation
- Pollution
- Sludge
ASJC Scopus subject areas
- General Chemistry
- General Chemical Engineering
- Industrial and Manufacturing Engineering