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Fig. 2. Influence of patchwise heterogeneity on colloid transport. (a) Zeta potential as a function of solution pH for clean sand grains (filled circles), aminosilane-modified sand grains (filled triangles), and various mixtures of aminosilane-modified and clean sand grains (open symbols). Zeta potentials were calculated from measured streaming potentials. Experiments were conducted with 10–3 M NaCl as a background electrolyte at a temperature of 21°C. (b) Colloid transport in chemically heterogeneous granular porous medium at pH 5.6 to 5.8 and solution ionic strength of 10–3 M. Colloid breakthrough curves are expressed as normalized colloid concentration at the column effluent as a function of pore volume for various mixtures of aminosilane-modified and clean sand grains (ranging from clean sand, 0%, for the top curve to 100% for the bottom curve) (Elimelech et al., 2000).
