Lepidocrocite and its heat-treated forms as effective arsenic adsorbents in aqueous medium

Eveliina Repo, Marko Mäkinen, Selvaraj Rengaraj, Gomathi Natarajan, Amit Bhatnagar, Mika Sillanpää

Research output: Contribution to journalArticle

39 Citations (Scopus)

Abstract

The aim of this study was to investigate the adsorption potential of heat treated lepidocrocites (γ-FeOOH) towards As(III) and As(V) ions in aqueous solutions. Initially, mesoporous lepidocrocite was synthesized, treated at different temperatures, and characterized using various analytical techniques. During the heating, transformation of lepidocrocite into hematite was observed. The adsorption of As(III) and As(V) was studied by batch experiments and the effects of different operational parameters e.g., adsorbent dose, solution pH, contact time, and the initial concentration of As(III)/(V) (isotherms) were studied. Lepidocrocite treated at 250°C exhibited >99% and 94% adsorption from 50. mg/L As(V) and As(III) solutions, respectively with an adsorbent dose of 2.5. g/L. The highest uptake capacity was obtained for As(III) (55. mg/g) on lepidocrocite without the heat treatment and for As(V) (38. mg/g) on lepidocrocite treated at 250°C, which was assigned to be a mixture of maghemite and hematite. The adsorption kinetic data fitted well with the pseudo-second-order model and the BiLangmuir isotherm had the best applicability to describe the adsorption equilibrium.

Original languageEnglish
Pages (from-to)159-169
Number of pages11
JournalChemical Engineering Journal
Volume180
DOIs
Publication statusPublished - Jan 15 2012

Fingerprint

lepidocrocite
Arsenic
Adsorbents
arsenic
Adsorption
adsorption
Hematite
Isotherms
hematite
isotherm
maghemite
Contacts (fluid mechanics)
Heat treatment
Hot Temperature
ferric oxide
analytical method
Heating
aqueous solution
Kinetics
heating

Keywords

  • Adsorption
  • Arsenic
  • Lepidocrocite
  • Metal removal
  • Water treatment

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Chemistry(all)
  • Industrial and Manufacturing Engineering
  • Environmental Chemistry

Cite this

Lepidocrocite and its heat-treated forms as effective arsenic adsorbents in aqueous medium. / Repo, Eveliina; Mäkinen, Marko; Rengaraj, Selvaraj; Natarajan, Gomathi; Bhatnagar, Amit; Sillanpää, Mika.

In: Chemical Engineering Journal, Vol. 180, 15.01.2012, p. 159-169.

Research output: Contribution to journalArticle

Repo, Eveliina ; Mäkinen, Marko ; Rengaraj, Selvaraj ; Natarajan, Gomathi ; Bhatnagar, Amit ; Sillanpää, Mika. / Lepidocrocite and its heat-treated forms as effective arsenic adsorbents in aqueous medium. In: Chemical Engineering Journal. 2012 ; Vol. 180. pp. 159-169.
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AB - The aim of this study was to investigate the adsorption potential of heat treated lepidocrocites (γ-FeOOH) towards As(III) and As(V) ions in aqueous solutions. Initially, mesoporous lepidocrocite was synthesized, treated at different temperatures, and characterized using various analytical techniques. During the heating, transformation of lepidocrocite into hematite was observed. The adsorption of As(III) and As(V) was studied by batch experiments and the effects of different operational parameters e.g., adsorbent dose, solution pH, contact time, and the initial concentration of As(III)/(V) (isotherms) were studied. Lepidocrocite treated at 250°C exhibited >99% and 94% adsorption from 50. mg/L As(V) and As(III) solutions, respectively with an adsorbent dose of 2.5. g/L. The highest uptake capacity was obtained for As(III) (55. mg/g) on lepidocrocite without the heat treatment and for As(V) (38. mg/g) on lepidocrocite treated at 250°C, which was assigned to be a mixture of maghemite and hematite. The adsorption kinetic data fitted well with the pseudo-second-order model and the BiLangmuir isotherm had the best applicability to describe the adsorption equilibrium.

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