Influence of Electrolytes on the Thixotropy of Ferric Aluminum Magnesium Hydroxide‐Montmorillonite Suspensions

Abstract

The thixotropy of suspensions consisting of ferric aluminum magnesium hydroxide (Fe‐Al‐Mg‐MMH) and Na‐montmorillonite (MT) is examined with special emphasis on the influence of electrolytes. When NaCl or MgCl2 is added into the Fe‐Al‐Mg‐MMH/MT suspension, the thixotropy of the suspension may change (if positive) from positive and complex into negative, but NaCl or MgCl2 can't alter the thixotropic type of a negatively thixotropic suspension. When AlCl3 was added to positive thixotropic system can be transformed to a complex one, whereas a complex and negative thixotropic suspension remains unchanged, for additions less than 0.01 mol/L; when the addition level of AlCl3 increases, all types of thixotropic systems are changed to non‐thixotropic. In addition, NaCl and MgCl2 make the initial viscosity measured after cessation of intensive shearing increase, but the value of the viscosity decreased rapidly with time. The equilibrium viscosity of the suspension decreased gradually with increasing concentrations of NaCl and MgCl2 in the suspension. With increasing concentration of AlCl3, the equilibrium viscosities of the positive thixotropic suspension and the complex thixotropic suspension increase at first, but decrease later, and the equilibrium viscosity of negative thixotropic suspensions decrease gradually.