The Formation and Properties of Zeolite-A and Zeolite-X through Geopolymerisation of Metakaolin

摘要

This study was aimed at experimentally investigate the formation of zeolite-A and zeolite-X through geopolymerization routes. The samples were prepared by alkali-activation of metakaolinite at 70°C with Si:Al = 1.04 and 1.25 and Na:A 1= 0.6, 0.8, 1.0 while keeping the molar ratio of H_2O:Na_2O = 10. The physical and mechanical properties of the resulting materials were characterized by means of bulk density and porosity measurement, compressive strength and Vickers microhardness tests. Crystallinity level and the phase of the samples was examined by X-Ray Diffraction (XRD) while morphology and elemental composition of the samples were examined by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). It was found that zeolite-A and zeolite-X were able to produce through geopolymerisation of metakaolin. XRD and SEM-EDX analysis results showed that these materials were composed of zeolite-A or zeolite-X together with amorphous geopolymer. The zeolite X was only formed when ratio of Si:Al is 1.25 while zeolite A was formed at all ratio except ata Si:Al=1.25 and Na:Al=1.0. These materials have relatively low hardness and compressive strength, low density and high apparent porosity.