Recovery of iron/iron oxide nanoparticles from solution: Comparison of methods and their effects

James T. Nurmi, Vaishnavi Sarathy, Paul G. Tratnyek, Donald R. Baer, James E. Amonette, Abhi Karkamkar

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


Most methods currently being used to recover Fe0-core/oxide-shell nanoparticles from solutions (including the solvents they are synthesized or stored in) are potentially problematic because they may alter the particle composition (e.g., depositing salts formed from solutes) or leave the particles prone to transformations during subsequent storage and handling (e.g., due to residual moisture). In this study, several methods for recovery of nanoparticles from aqueous solution were studied to determine how they affect the structure and reactivity of the recovered materials. Simple washing of the nanoparticles during vacuum filtration (i.e., "flash drying") can leave up to ∼17 wt% residual moisture. Modeling calculations suggest this moisture is mostly capillary or matric water held between particles and particle aggregates, which can be removed by drying for short periods at relative vapor pressures below 0.9. Flash drying followed by vacuum drying, all under N2, leaves no detectable residue from precipitation of solutes (detectable by X-ray photoelectron spectroscopy, XPS), no significant changes in overall particle composition or structure (determined by transmission electron microscopy, TEM), and negligible residual moisture (by thermogravimetric analysis, TGA). While this improved flash-drying protocol may be the preferred method for recovering nanoparticles for many purposes, we found that Feo-core/oxide-shell nanoparticles still exhibit gradual aging during storage when characterized electrochemically with voltammetry.

Original languageEnglish (US)
Pages (from-to)1937-1952
Number of pages16
JournalJournal of Nanoparticle Research
Issue number5
StatePublished - May 2011


  • Colloids
  • Flash drying
  • Linear sweep voltammetry
  • Recovery
  • Thermogravimetric analysis
  • Transmission electron microscopy
  • Weight loss
  • X-ray diffraction
  • X-ray photoelectron spectroscopy

ASJC Scopus subject areas

  • Bioengineering
  • Atomic and Molecular Physics, and Optics
  • Chemistry(all)
  • Modeling and Simulation
  • Materials Science(all)
  • Condensed Matter Physics


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