Torres, L. G., Iturbe, R., Snowden, M. J. ORCID: 0000-0002-1087-2692, Chowdhry, B. Z. and Leharne, S. A. (2007) Preparation of o/w emulsions stabilized by solid particles and their characterization by oscillatory rheology. Colloids and Surfaces A: Physiochemical and Engineering Aspects, 302 (1-3). pp. 439-448. ISSN 0927-7757 (doi:https://doi.org/10.1016/j.colsurfa.2007.03.009)

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Abstract

The purpose of this investigation was to examine the preparation and characterisation of hexane-in-water emulsions stabilised by clay particles. These emulsions, called Pickering emulsions, are characterised by the adsorption of solid particles at the oil/water (o/w) interface. The development of an elastic film at the o/w interface following the adsorption of colloidal particles helps to promote emulsion stability. Three different solid materials were used: silica sand, kaolin, and bentonite. Particles were added to the liquid mixtures in the range of 0.5–10 g dm−3. Emulsions were prepared using o/w ratios of 0.1, 0.2, 0.3, and 0.4. The effect of sodium chloride, on the stability of the prepared emulsions, was assessed in the range of 0–0.5 mol dm−3. In addition the use of a cationic surfactant hexadecyl-trimethylammonium bromide (CTAB) as an aid to improving emulsion stability was assessed in the concentration range of 0–0.05% (w/v). Characterisation of emulsion stability was realised through measurements of rheological properties including non-Newtonian viscosity, the elastic modulus, G', the loss modulus, G", and complex modulus, G*. The stability of the emulsions was evaluated immediately after preparation and 4 weeks later.
Using the stability criteria, that for highly stable emulsions: G' > G" and both G' and G" are independent of frequency (varpi) it was concluded that highly stable emulsions could be prepared using a bentonite concentration of 2% (or more); an o/w ratio greater than 0.2; a CTAB concentration of 0.01%; and a salt concentration of 0.05 M or less—though salt was required.

Item Type:	Article
Uncontrolled Keywords:	bentonite, kaolin, oscillatory rheology, pickering emulsions, sand
Subjects:	Q Science > QD Chemistry Q Science > QC Physics
Faculty / School / Research Centre / Research Group:	Faculty of Engineering & Science > School of Science (SCI) Faculty of Education, Health & Human Sciences > School of Human Sciences (HUM)
Related URLs:	Publisher Organisation Organisation
Last Modified:	09 Oct 2021 04:46
URI:	http://gala.gre.ac.uk/id/eprint/2690

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