Chemistry of soil minerals. Part XIV. Action of some basic solutions on metakaolinite and kaolinite

Abstract

Some reactions have been studied at 80 °C between aqueous alkaline media and metakaolinite with and without added silica. The bases employed were TlOH, Ba(OH)₂+ TlOH, Ba(OH)₂+ LiOH, and Ba(OH)₂+ NaOH. A similar study was made of kaolinite with aqueous Ba(OH)₂+ LiOH. Kaolinite was less reactive than metakaolinite and yielded different reaction products. Non-zeolites formed included a barium silicate hydrate, barium aluminate, and a phase similar to cymrite. Three unidentified Tl-bearing species were also formed in minor yields. Zeolites of the following kinds were grown: those of edingtonite type containing Ba²⁺+ Tl⁺ or Ba²⁺+ Li⁺; variants of zeolite L, containing Ba²⁺+ Tl⁺, Ba²⁺+ Li⁺, or Ba²⁺+ Na⁺; harmotome- or phillipsite-types containing Ba²⁺+ Li⁺ or Ba²⁺+ Na⁺; and zeolites like gismondite with Ba²⁺+ Na⁺, like gmelinite and containing Ba²⁺+ Na⁺, and like yugawaralite containing Ba²⁺+ Li⁺. A lithium-bearing zeolite with no natural counterpart and in which the cations were Ba²⁺+ Li⁺ was also grown.

Properties of a number of these phases have been examined. From the present and earlier work, it appears that an important factor in promoting growth of chabazite-, edingtonite-, and phillipsite-type zeolites and of zeolite L is the presence of a sufficient amount of at least one of the cations K⁺ or Ba²⁺. On the other hand a sodic environment favours gismondite-, gmelinite-, and faujasite-type zeolites, and Linde A.