H+ LI+ AND H+/K+ EXCHANGE ON DELAMINATED MUSCOVITE MICA/

Muscovite mica was delaminated by heating with concentrated lithium ni trate solution. The delamination occurred through partial replacement of the alkali counterions originally present by lithium. The H+/Li+ ex change was studied in dilute nitric acid. With delaminated mica it was possible to follow the ion exchange by measuring the change in conduc tivity of the reaction mixture. The exchange was also followed by meas uring the amount of released lithium and was found to be fast. When th e adsorbed lithium ions were replaced by potassium, the mica platelets collapsed to stacks with lower accessible surface area, and the ion e xchange capacity was reduced to one-fifth of the original value. This was attributed to the smaller short-range repulsive (hydration) forces of the potassium ions. The H+/K+ exchange on delaminated mica was slo wer than the corresponding H+/Li+ exchange and its equilibrium constan t was much smaller than that of the H+/Li+. The affinity of oxonium io ns to the muscovite surface is much higher than that of lithium but is comparable to that of potassium. (C) 1998 Academic Press.