11JUL06A fresh mica sample was pretreated in pH 11 KOH solution and tested in a 112 μS/cm KCl solution. CTAB was added to create a 1 mM CTAB solution and tested for 24 hours. The zeta potential increased as the CTAB adsorbed. A stable final zeta potential of –22mV was observed.
18JUL06A fresh mica sample was pretreated in pH 11 KOH solution and tested in a 106 μS/cm KCl solution. CTAB was added to create a 2 μM CTAB solution. This suggests that a higher concentration of CTAB correlates to a more positive zeta potential.
Adsorption of CTAB on Mica. Fresh pretreated mica samples were exposed to 1mM KCl, pH= 5.5, containing various amounts of CTAB. At 1μM CTAB and below, the adsorption curves were indistinguishable. At 2 μM CTAB and above, substantially more CTAB was adsorbed. At concentrations 5μM CTAB and above, the CTAB stabilized bubbles entrained by the stirring, introducing noise in the data.
21JUN06 and 22JUN06
June 21st. A fresh mica sample was pretreated in pH 11.7 solution for 30 minutes and 1mM CTAB. The sample was than placed in 1 mM KCl (pH 5.5) that was initially free of CTAB. The CTAB desorbed.
June 22nd. A fresh mica sample was pretreated in pH 11 solution for 30 minutes and 1mM CTAB. The CTAB was then desorbed in the solution from June 21st. It is thought that the difference in zeta potential is due to the residual CTAB from the previous experiment.
23JUN06 A fresh mica sample was pretreated in pH 11 solution (30 min.) and 1mM CTAB (1.5 hr). The CTAB was desorbed in 1mM KCl at pH 5.5. Another fresh mica sample was pre-treated in pH 11 solution (30 min.) and 1mM CTAB (2.5 hr). The CTAB was then desorbed in 1mM KCl from the previous experiment.
