Comparison and understanding of fluoride removal mechanism in Ca2+, Mg2+ and Al3+ ion assisted electrocoagulation process using Fe and Al electrodes

Kadarkarai Govindan, Mohan Raja, Subramanian Uma Maheshwari, Michael Noel, Yoram Oren

Research output: Contribution to journalArticlepeer-review

47 Scopus citations

Abstract

The present study is to scrutinize the effect of Ca2+, Mg2+ and Al3+ ion on fluoride removal by electrocoagulation (EC) using Fe and Al electrode. The effect of charge loading (Qe), concentration of cations (Mn+ = Ca2+, Mg2+ and Al3+) and anions (Xn- = NO3-, SO42- and Cl-) on fluoride removal is analysed in detail. Experimental results ensure that, in absence of Mn+, the maximum fluoride removal efficiency up to 60% for Al and 18% for Fe is achieved by EC at Qe 1620 C L-1 when the initial fluoride concentration is 0.53 mM. Nonetheless, the initial fluoride concentration (0.53 mM) is reduced to 0.06 mM (WHO recommended limit of fluoride) with the removal of efficiency up to 87% by the addition of 0.16 and 0.25 mM of Al3+ (as AlCl3) in EC with Al and Fe electrodes, respectively. The maximum fluoride removal efficiency of 90% for Fe electrodes and 99% for Al electrodes is obtained through Al3+ assisted EC and Mg2+ assisted EC, respectively. The effect of co-existing anions on fluoride removal has emphasized that SO42- ions show pronounced effect compared to NO3- and Cl-. In addition to that, to elucidate the fluoride removal mechanism, crystalline nature and composition of the sludge generated in defluoridation processes by Mn+ assisted EC are also been characterized using XRD, SEM and FT-IR.

Original languageEnglish
Pages (from-to)1784-1793
Number of pages10
JournalJournal of Environmental Chemical Engineering
Volume3
Issue number3
DOIs
StatePublished - 1 Sep 2015

Keywords

  • Al electrodes
  • Fe electrodes
  • Fluoride removal
  • Metal ion assisted EC
  • Sludge characterization

ASJC Scopus subject areas

  • Chemical Engineering (miscellaneous)
  • Waste Management and Disposal
  • Pollution
  • Process Chemistry and Technology

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