Interaction Forces Between Colloidal Silica in Aqueous Inorganic and Natural Organic Electrolyte Solutions

Robert F. Considine; Calum J. Drummond; David R. Dixon

doi:10.1071/CH05154

RESEARCH ARTICLE

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Interaction Forces Between Colloidal Silica in Aqueous Inorganic and Natural Organic Electrolyte Solutions

Robert F. Considine ^A , Calum J. Drummond ^B ^D and David R. Dixon ^C

+ Author Affiliations

- Author Affiliations

^A Melbourne Water, PO Box 4342, Melbourne VIC 3001, Australia.

^B CSIRO Molecular and Health Technologies, North Ryde NSW 1670, Australia.

^C ARC Special Research Centre for Particulate Fluids Processing, Department of Chemical & Biomolecular Engineering, University of Melbourne, Melbourne VIC 3010, Australia.

^D Corresponding author. Email: calum.drummond@csiro.au

Australian Journal of Chemistry 58(12) 837-844 https://doi.org/10.1071/CH05154
Submitted: 21 June 2005 Accepted: 23 November 2005 Published: 20 December 2005

Abstract

Atomic force microscopy (AFM) has been used to measure the force of interaction between pairs of silica colloids in aqueous inorganic and natural organic electrolyte solutions. In solutions containing a mixture of mono- and divalent inorganic ions, the force measurements on approach can be understood in terms of an electrical double-layer interaction, with decay lengths being comparable to the predicted Debye length. The force of interaction on separation in these mixed electrolyte solutions has been found to be entirely repulsive. Force measurements in a mixture of monovalent ions and natural organic matter (NOM), which is a common component of natural waters, are also reported. The decay length of the electrical double-layer interaction is observed to decrease upon addition of NOM. Force measurements on separation are characterized by pH-dependent adhesion, which has been interpreted in terms of specific surface adsorption and the intermolecular interaction of NOM. A comparison with particle micro-electrophoresis data for the silica colloids in the mixed electrolyte solutions has also been made.

Acknowledgments

R.F.C. gratefully acknowledges the support and friendship of S. Gillies. R.F.C. was the recipient of an Australian Postgraduate Research Award when the experimental work was conducted. The authors also thank the University of South Australia and the Cooperative Research Centre for Water Quality and Treatment for support. C.J.D. is the recipient of an Australian Research Council Federation Fellowship.

References

Interaction Forces Between Colloidal Silica in Aqueous Inorganic and Natural Organic Electrolyte Solutions

Abstract

Acknowledgments

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