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A hydrofluoric acid-free method to dissolve and quantify silica nanoparticles in aqueous and solid matrices

  • Bossert, David Adolphe Merkle Institute, University of Fribourg, Switzerland
  • Urban, Dominic A. Adolphe Merkle Institute, University of Fribourg, Switzerland
  • Maceroni, Mattia Adolphe Merkle Institute, University of Fribourg, Switzerland
  • Ackermann-Hirschi, Liliane Adolphe Merkle Institute, University of Fribourg, Switzerland
  • Haeni, Laetitia Adolphe Merkle Institute, University of Fribourg, Switzerland
  • Yajan, Phattadon Adolphe Merkle Institute, University of Fribourg, Switzerland
  • Spuch-Calvar, Miguel Adolphe Merkle Institute, University of Fribourg, Switzerland
  • Rothen-Rutishauser, Barbara Adolphe Merkle Institute, University of Fribourg, Switzerland
  • Rodriguez-Lorenzo, Laura Adolphe Merkle Institute, University of Fribourg, Switzerland - Nano4Enviroment Unit, Water Quality Group, INL - International Iberian Nanotechnology Laboratory, Braga, Portugal
  • Petri-Fink, Alke Adolphe Merkle Institute, University of Fribourg, Switzerland - Chemistry Department, University of Fribourg, Switzerland
  • Schwab, Fabienne Adolphe Merkle Institute, University of Fribourg, Switzerland
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    28.05.2019
Published in:
  • Scientific Reports. - 2019, vol. 9, no. 1, p. 7938
English As the commercial use of synthetic amorphous silica nanomaterials (SiO2-NPs) increases, their effects on the environment and human health have still not been explored in detail. An often-insurmountable obstacle for SiO2-NP fate and hazard research is the challenging analytics of solid particulate silica species, which involves toxic and corrosive hydrofluoric acid (HF). We therefore developed and validated a set of simple hydrofluoric acid-free sample preparation methods for the quantification of amorphous SiO2 micro- and nanoparticles. To circumvent HF, we dissolved the SiO2- NPs by base-catalyzed hydrolysis at room temperature or under microwave irradiation using potassium hydroxide, replacing the stabilizing fluoride ions with OH−, and exploiting the stability of the orthosilicic acid monomer under a strongly basic pH. Inductively coupled plasma – optical emission spectroscopy (ICP-OES) or a colorimetric assay served to quantify silicon. The lowest KOH: SiO2 molar ratio to effectively dissolve and quantify SiO2-NPs was 1.2 for colloidal Stöber SiO2-NPs at a pH >12. Fumed SiO2-NPs (Aerosil®) or food grade SiO2 (E551) containing SiO2-NPs were degradable at higher KOH: SiO2 ratios >8000. Thus, hydrofluoric acid-free SiO2- NP digestion protocols based on KOH present an effective (recoveries of <84%), less hazardous, and easy to implement alternative to current methods.
Faculty
Faculté des sciences et de médecine
Department
Département de Chimie
Language
  • English
Classification
Chemistry
License
License undefined
Identifiers
Persistent URL
https://folia.unifr.ch/unifr/documents/307956
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