ered silicates have been published (6, 7), little is known Muscovite mica was delaminated by heating with concenabout this reaction in muscovite mica and there are many trated lithium nitrate solution. The delamination occurred open questions 9). This is probably due to the analytithrough partial replacement of the alkali counterions originally cal difficulties arising from its small surface area, i.e., the present by lithium. The H / / Li / exchange was studied in dilute relatively low ion exchange capacity of this mineral which nitric acid. With delaminated mica it was possible to follow the is typically around one hundred times lower than that of ion exchange by measuring the change in conductivity of the vermiculite or montmorillonite. However, this problem can reaction mixture. The exchange was also followed by measuring be overcome by delaminating muscovite through heating the amount of released lithium and was found to be fast. When with lithium nitrate (10), thus increasing its surface area. In the adsorbed lithium ions were replaced by potassium, the mica platelets collapsed to stacks with lower accessible surface area, this way, a mica with one hundred times higher ion exchange and the ion exchange capacity was reduced to one-fifth of the capacity was obtained (11). Another advantage of delamioriginal value. This was attributed to the smaller short-range nated mica is its chemically uniform surface, i.e., the presrepulsive ( hydration ) forces of the potassium ions. The H / / K / ence of one single type of ion on the surface, which simpliexchange on delaminated mica was slower than the correspondfies the study of the exchange reaction.
ing H / / Li / exchange and its equilibrium constant was much Ion exchange studies are usually performed in aqueous smaller than that of the H / / Li / . The affinity of oxonium ions media and knowledge of the exchange of surface ions to the muscovite surface is much higher than that of lithium against H / or H 3 O / is therefore of fundamental imporbut is comparable to that of potassium.