Determination of surface properties of iron hydroxide-coated alumina adsorbent prepared for removal of arsenic from drinking water

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Abstract

A novel type adsorbent was prepared by in situ precipitation of Fe(OH) 3 on the surface of activated Al2O3 as a support material. The iron content of the adsorbent was 0.31±0.003% m/m (56.1 mmol/g); its mechanical and chemical stability proved to be appropriate in solutions. The total capacity of the adsorbent was 0.12 mmol/g, and the pH of zero point of charge, pHzpc =6.9±0.3. Depending on the pH of solutions, the adsorbent can be used for binding of both anions and cations, if pHeq < pHzpc anions are sorbed on the surface of adsorbent (S) through {S-OH2+} and {S-OH} groups. A graphical method was used for the determination of pHiep (isoelectric points) of the adsorbent and values of pHiep =6.1±0.3 for As(III) and pHiep =8.0±0.3 for As(V) ions were found. The amount of surface charged groups (Q) was about zero within the a pH range of 6.5-8.6, due to the practically neutral surface formed on the adsorption of As(V) ions. At acidic pH (pH 4.7), Q=0.19 mol/kg was obtained. The adsorption of arsenate and arsenite ions from solutions of 0.1-0.4 mmol/L was represented by Langmuir-type isotherms. A great advantage of the adsorbent is that it can be used in adsorption columns, and low waste technology for removal of arsenic from drinking water can be developed.

Original languageEnglish
Pages (from-to)71-77
Number of pages7
JournalJournal of colloid and interface science
Volume284
Issue number1
DOIs
Publication statusPublished - Apr 1 2005

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Keywords

  • Adsorption
  • Alumina
  • Arsenate
  • Arsenite
  • Iron hydroxide
  • Isoelectric points
  • Isotherms
  • Zero point of charge

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Surfaces, Coatings and Films
  • Colloid and Surface Chemistry

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