Rheology of Colloidal Dispersions: Deflocculation of Kaolin Dispersions

0395240 - ÚCHP 2014 CZ eng V - Research Report
Guerreiro, M.I.A. - Růžička, Marek - Pěnkavová, Věra
Rheology of Colloidal Dispersions: Deflocculation of Kaolin Dispersions.
Praha: Ústav chemických procesů AV ČR, v. v. i, 2013. 77 s. 2.
Institutional support: RVO:67985858
Keywords : kaolin dispersions * yield strss * viscoplastic fluids
Subject RIV: CI - Industrial Chemistry, Chemical Engineering

All inorganic additives in their optimal concentrations proved to be effective at reducing the initial viscosity to 1%. In the case of NaOH two different trends were observed: firstly this additive behaved as a deflocculant agent where, at its optimal range of concentrations, the viscosity of kaolin dispersion reduced to its minimal value, secondly when used at concentrations above its optimal range, sodium hydroxide behaved like a flocculant agent increasing strongly the viscosity of kaolin dispersions. The possible cause was attributed to an excess of Na+ and OH- species in bulk media that promoted the reversible effect. Similar effect was also reported for NaCMC at high and medium molar weight, were the viscosity firstly decreased to a certain concentration of additive and then above that concentration started to increase. Thus low molar weight NaCMC was the most effective among the organic additives since it decreased the viscosity to 10% of initial viscosity. Qualitative evaluation showed that organic additives promoted more stable dispersions, in contrast to poor stability offered by the inorganic additives, with exception of NaOH that provided dispersions with good stability inside of its optimal range.
Permanent Link: http://hdl.handle.net/11104/0223333