Effect of ionic strength and pH on hydraulic properties and structure of accumulating solid assemblages during microfiltration of montmorillonite suspensions

Influence of calcium and silica on hydraulic properties of sodium montmorillonite assemblages under alkaline conditions

“…Colloidal montmorillonite suspensions were prepared using the procedure established by Santiwong et al [14]. Briefly, the montmorillonite was obtained from a naturally-sourced Australian bentonite (TRUBOND; Unimin, Australia), which was dispersed in Milli-Q water (Millipore; USA) and size-fractionated by centrifugation before mixing with NaCl (to 1 mol/L).…”

“…The dead-end filtration methodology employed in this study has been used previously to determine the hydraulic properties of montmorillonite suspensions [14,24]. Briefly, the sorptivity, a measure of the diffusivity/water-content relationship [25], is obtained from the relationship (Eq.…”

“…In fact, many studies examining the impact of changes to solution pH and cation concentration have been undertaken, including those of Benna et al [8], Carlson et al [11], Di Maio [12] and Mohan and Folger [13]. In focussing on membrane filtration fouling, Santiwong and colleagues [14] showed that concentrations of calcium (50 mM) at pH 4 had the ability to increase the hydraulic conductivity of a Na-montmorillonite 10-fold. Supported by electron microscopy, the authors proposed that calcium ions induced structural changes in the nematically ordered assemblage which resulted in significant enhancement in hydraulic conductivity in the samples exposed to solutions containing elevated calcium concentrations.…”

Influence of pH and Compression on Electrohydrodynamic Effects in Nanoporous Packed Beds

“…The coefficients C 11 to C 22 depend on the particle charge and on the pore structure of the packed bed, which is influenced by the formation of agglomerates in the suspension from which the packed bed was formed. The stability of suspensions against agglomeration is described by the DLVO theory [1,4,8]. A packed bed formed from a stable suspension has a dense structure with a homogeneous pore size distribution and a low permeability.…”

“…Further, the pore structure itself also depends on the same parameters as the surface charge and the ion distribution in the EDL, that is, the pH value and the ionic strength of the liquid [1,4]. Many researchers describe EHT with elaborate spherical cell models, for which the continuity and stokes equation are solved (see [5] for a recent review).…”