Mixed-emulsifier stabilised emulsions: Investigation of the effect of monoolein and hydrophilic silica particle mixtures on the stability against coalescence |
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Authors: | Pichot R Spyropoulos F Norton I T |
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Affiliation: | aENSCP-LECA-CNRS-Université Paris 6, 11, Rue Pierre et Marie Curie, 75005 Paris, France;bThe Vinca Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade, Serbia;cEDF R&D/MFTT 6, Quai Watier-BP 49, 78400 Chatou, France |
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Abstract: | An experimental circulating water loop has been constructed to study the deposition of hematite particles of average diameter 320 nm on polypropylene pipe walls in the ranges pH 4–11, Re 3300–17,700 at 25 °C. Real-time turbidimetric measurements were used to measure the deposited concentrations. Results showed that the deposition rate increased when pH decreased and when the flow rate increased. Adhesion was observed even under repulsive electrostatic conditions (pH > 7), where the surfaces of hematite and polypropylene were both negative, indicating that the kinetic energy of at least a part of the particles surpassed the electrostatic repulsive potentials. The experimental curves were fitted by a model assuming simultaneous adhesion and removal of particles, leading to adhesion and removal rate constants, whose values depend on pH and flow rate. Removal is negligible below pH 9. |
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Keywords: | Hematite Particle Deposition Transport processes Colloids Kinetics Adhesion Turbulent flow |
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