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Effect of shear, temperature and pH on the dynamics of salt induced coagulation of wood resin colloids

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Lee, R and Stack, KR and Richardson, DE and Lewis, T and Garnier, G (2012) Effect of shear, temperature and pH on the dynamics of salt induced coagulation of wood resin colloids. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 396. pp. 106-114. ISSN 0927-7757

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Abstract

The effect of pH, temperature and shear on the coagulation dynamics of a wood resin suspension destabilized by salt additions was investigated. Stability of wood resin colloids was measured as a function of time using a photometric dispersion analyser (PDA) upon the step addition of salt solutions. Colloidal stability upon salt addition was found to be a function of pH (directly related to colloidal wood resin charge). This follows the predictions from the Derjaguin, Landau, Verwey and Overbeek (DLVO) theory. In general temperature also affected colloidal stability according to expectations. However, the effects were found to be strongly related to salt type. The effect of shear on the stability of a colloidal suspension was more important than expected. At low shear, the critical coagulation concentration of colloidal wood resins scaled with salt valency to the −6 power. Deviations from the Shultz–Hardy rule become important as shear was increased and a critical coagulation concentration (CCC) proportional to the counter ion charge to the power of 7 (CCC ∝ z−7) relationship was measured at the highest shear. We suggest a relationship of the form: CCC ∝ (Ωz)−6τ or CCC ∝ [z−6τ + Ω] where Ω = f(G) and τ = g(G). An additional term would be required for the systems under orthokinetic conditions usually found in industry.

Item Type: Article
Keywords: Wood resin Colloid Pitch Stability Critical coagulation concentration Shear Temperature Charge Salt DLVO theory
Journal or Publication Title: Colloids and Surfaces A: Physicochemical and Engineering Aspects
Page Range: pp. 106-114
ISSN: 0927-7757
Identification Number - DOI: 10.1016/j.colsurfa.2011.12.049
Additional Information: The definitive version is available at http://www.sciencedirect.com
Date Deposited: 28 Feb 2012 23:24
Last Modified: 04 Sep 2013 05:17
URI: http://eprints.utas.edu.au/id/eprint/12718
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