A selective preparation of phillipsite and sodalite from perlite

The preparation of commercially valuable materials, i.e. phillipsite, sodalite octahydrate and faujasite from perlite via inexpensive direct treatment with sodium hydroxide solution, at low temperatures of 70–100 °C under autogeneous pressure, is reported. The formation of phillipsite and sodalite is shown to be selective, whereas the occurring of faujasite is always found with phillipsite. The influences of sodium hydroxide solution concentration, reaction temperature and time on the type of the solid products, and the amount of Na+ and K+ incorporated in the zeolitized solids were investigated. The relation between the type of the synthesized zeolites and the uptake of Na+ and the leaching of K+ is described, and shown to be significant for further investigation as to expand the application as a cation exchanger.