Lee, R and Stack, K and Richardson, D and Lewis, T and Garnier, G, Multi-salt coagulation of soft pitch colloids, Colloids and Surfaces A: Physicochemical and Engineering Aspects: An International Journal Devoted to The Applications and Principles of Colloid and Interface Science, 409 pp. 74-80. ISSN 0927-7757 (2012) [Refereed Article]
Copyright 2012 Elsevier B.V.
The dynamic coagulation of colloidal pitch was quantified under orthokinetic conditions. The effects of single salt, multiple salt and cation valency on the stability of the colloidal pitch were investigated as a function of salt concentration. Critical coagulation concentrations (CCCs) were determined for a range of individual cations. The CCC in the presence of a number of divalent or trivalent cations was investigated to gain an understanding of the effect of multiple salts normally found in industrial systems.Electrostatic destabilisation of wood resin colloids by a single salt is strongly influenced by salt valency (z) and mostly independent of the individual cation (at constant z). Addition of a second cation to solution resulted in a decrease in the CCC for both calcium and aluminium ions in the presence of sodium ions. The decrease in the CCC for the wood resin colloids was non-linear and showed restabilisation of the colloids above the CCC, unlike the effects observed for a single salt. Comparison of the experimental CCC results with the DVLO theory indicates that a higher Hamaker constant than reported for the interaction of abietic acid with talc in water (used here as a model interaction) is needed. This suggests that the aggregation process of the wood resin colloids involves a stronger interaction than abietic acid with talc. Experimental CCC values for divalent and trivalent ions were also lower than those predicted theoretically. To obtain agreement between theory and experimental results, reduced Stern potentials and higher Hamaker constants were required, suggesting specific ion adsorption of the multivalent cations is occurring to reduce surface charge of the colloid.
|Item Type:||Refereed Article|
|Keywords:||soft colloid, pitch, multi-salt coagulation, DLVO theory, critical coagulation concentration (CCC), adsorption|
|Research Division:||Chemical Sciences|
|Research Group:||Physical Chemistry (incl. Structural)|
|Research Field:||Colloid and Surface Chemistry|
|Objective Group:||Wood, Wood Products and Paper|
|Objective Field:||Pulp and Paper|
|UTAS Author:||Lee, R (Mr Roland Lee)|
|UTAS Author:||Stack, K (Dr Karen Stack)|
|UTAS Author:||Lewis, T (Dr Trevor Lewis)|
|Web of Science® Times Cited:||7|
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