Effect of acid and alkaline treatment on physicalchemical properties of surface of natural glauconite

Physical-chemical properties of the structure and the surface of natural (Glt-Nat) and modified by2M H2SO4 (Glt-Ac); 2M NaOH (Glt-Alk) aluminosilicate samples containing glauconite were studied bymeans of XRD, SEM, BET-methods and catalytic conversion of methylbutynol (MBOH). It was observedthat investigated sample was a mixture of mixed layered minerals of illite-smectite (I-S) series, having a I:Sratio of 50:50 and 80:20. The content of the mixed-layer mineral phase (I:S=50:50) changed as follows: 30-35% for Glt-Nat; 20-25% for Glt-Ac and 10-15% for Glt-Alk. The elemental composition did notsignificantly change after both types of treatment, whereas a twofold increase in specific surface area of GltAcwas observed. The catalytic conversion of MBOH after 10 min of reaction changed in the order: Glt-Ac(25.4%) > Glt-Nat (23.5%) > Glt-Alk (5.7%). The product yields distribution confirmed presence of bothacid and basic sites on the surface, with the major contribution of acid sites. According to experimental yieldsof products formed over acid pathway of the reaction, acidity of unit surface area varied in the order: Glt-Nat> Glt-Ac > Glt-Alk. The chemical modification of natural sample caused an alteration of its surfaceacidity/basicity as observed from the ratio (Ra/b values) of product yields normalized per unit area of surface.The highest Ra/b was found for Glt-Ac (97.5), which was 3 times higher as for Glt-Nat (33.1) and 7.7 timesthat for Glt-Alk (12.6).