Interfacial-chemistry mediated behavior of colloidal talc dispersions

被引:52
作者
Bremmell, KE [1 ]
Addai-Mensah, J [1 ]
机构
[1] Univ S Australia, Ian Wark Res Inst, Mawson Lakes, SA 5095, Australia
基金
澳大利亚研究理事会;
关键词
clay; talc; interfacial chemistry; rheology; metal ions; dewatering;
D O I
10.1016/j.jcis.2004.09.048
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Interfacial chemistry and rheological behavior of talc suspensions as a function of pH, talc solid content, and type and concentration of ions have been investigated using electrokinetic measurements, rheology, settling behavior, and solution analysis. Zeta potential measurements show a strong dependence on the pH history of the talc suspension that only occurs when the surface area (solid content) of the talc is high. Particle interactions measured through dispersion yield stress measurements show a similar dependence. Talc is a magnesium silicate mineral and the dependence seen in the electrokinetic properties in this study has been attributed to Mg(II) dissolution at low pH, and has been confirmed by solution analysis. At high solid content (>20 wt%), pronounced Mg(II) ion dissolution occurs at low pH values. Formation and adsorption of electropositive Mg(II) hydrolysis products occurs at high pH (>9), and these lead to zeta potential reduction and, at high solid contents, charge reversal. Particle interactions reflect the surface chemistry behavior. Consequently, for a freshly prepared suspension at high pH, the yield stress is lower compared to after the pH has been taken to 5 and subsequently increased. (C) 2004 Elsevier Inc. All rights reserved.
引用
收藏
页码:385 / 391
页数:7
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