Chemistry of soil minerals. Part XII. Transformations of metakaolinite with solutions containing barium hydroxide

Abstract

Metakaolinite, with or without additions of silica, readily reacts with aqueous solutions of barium hydroxide alone, of barium plus potassium hydroxides, and of barium plus tetramethylammonium hydroxides. In the range 80 to 100° barium hydroxide produced a polymorph of celsian, two unidentified zeolitic phases, Ba-T and Ba-N, and species having a structure resembling that of Lindezeolite L. From Ba(OH)₂+ KOH the zeolitic phases formed were of chabazite- and L-type, together with (Ba,K)-T and the non-zeolitic polymorph of celsian. From Ba(OH)₂+ N(CH₃)₄OH, in addition to this non-zeolite, near-erionites, L-type zeolites, and [Ba,N(CH₃)₄]-T were crystallised. The properties of some of the L-type zeolites have been particularly studied. They were prepared with a wide range in Si:Al ratios and in molecule sieving properties. They possessed good thermal stability, as did the H-enriched form of one of the most aluminous preparations.