Understanding regeneration of arsenate-loaded ferric hydroxide-based adsorbents

Binod Kumar Chaudhary, James Farrell

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Adsorbents comprising ferric hydroxide loaded on a variety of support materials are commonly used to remove arsenic from potable water. Although several studies have investigated the effects of support properties on arsenic adsorption, there have been no investigations of their effects on adsorbent regeneration. Furthermore, the effect of regenerant solution composition and the kinetics of regeneration have not been investigated. This research investigated the effects of adsorbent and regenerant solution properties on the kinetics and efficiency of regeneration of arsenate-loaded ferric hydroxide-based adsorbents. Solutions containing only 0.10-5.0 M NaOH or 0.10-1.0 M NaCl, as well as solutions containing both compounds, were used as regenerants. On all media, >99% of arsenate was adsorbed through complexation with ferric hydroxide. Arsenate recovery was controlled by both equilibrium and kinetic limitations. Adsorbents containing support material with weak base anion-exchange functionality or no anion-exchange functionality could be regenerated with NaOH solutions alone. Regeneration of media containing strong base anion (SBA)-exchange functionality was greatly enhanced by addition of 0.10 M NaCl to the NaOH regenerant solutions. Adsorbed silica had a significant effect on NaOH regeneration of media containing type I SBA-exchange functionality, but on other media, adsorbed silica had little impact on regeneration. On all media, 5-25% of arsenate was resistant to desorption in 1.0 M NaOH solutions. However, the use of 2.5-5.0 M NaOH solutions significantly reduced the desorption-resistant fraction.

Original languageEnglish (US)
Pages (from-to)353-360
Number of pages8
JournalEnvironmental Engineering Science
Volume32
Issue number4
DOIs
StatePublished - Apr 1 2015

Keywords

  • adsorbents
  • anion exchange
  • arsenate
  • ferric hydroxide
  • regeneration

ASJC Scopus subject areas

  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution

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