Role of surface precipitation in copper sorption by the hydrous oxides of iron and aluminum

K. G. Karthikeyan, Herschel A. Elliott, Jon Chorover

Research output: Contribution to journalArticlepeer-review

54 Scopus citations

Abstract

Isotherms were developed at pH 6.9 for adsorption (ADS) and coprecipitation (CPT) of Cu by hydrous oxides of Fe (HFO) and Al (HAO) to study the role of sorbate/sorbent ratio in metal cation removal. For low sorbate/sorbent conditions, HFO had a higher Cu retention capacity than HAO regardless of contact methodology. For either oxide, CPT was consistently more effective than ADS in removing Cu from solution. At high sorbate/sorbent ratios, surface precipitation dominates and the oxide's net cation retention capacity depends on the nature and solubility of the precipitate formed at the oxide-water interface. X-ray diffraction patterns and isotherms of HAO for both ADS and CPT suggest formation of a solid solution [e.g., CuAl2O4(s)] with dramatically lower solubility than Cu(OH)2(s) precipitated in bulk solution. In contrast, Cu precipitated on the HFO surface exhibited a solubility comparable to the bulk precipitated Cu(OH)2(s). Therefore, at high sorbate/sorbent ratios, HAO has a higher Cu 'apparent' sorption capacity than HFO. The relative utility of these oxides as metal scavengers thus depends markedly on sorbate/sorbent conditions.

Original languageEnglish (US)
Pages (from-to)72-78
Number of pages7
JournalJournal of Colloid And Interface Science
Volume209
Issue number1
DOIs
StatePublished - Jan 1 1999

Keywords

  • Copper
  • Hydrous aluminum oxide
  • Hydrous iron oxide
  • Isotherms
  • Sorption
  • Surface precipitation
  • X-ray diffraction

ASJC Scopus subject areas

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

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