Synthesis of Sodalite from Indonesian Kaolin with Conventional and Alkali Fusion Method

Abstract

Sodalite has been synthesized from Indonesian kaolin. Kaolin was converted into more reactive metakaolin using conventional and alkali fusion methods. In the conventional method, kaolin is calcined at a temperature of 700 °C for 3 hours. Meanwhile, in the alkali fusion method, the mixture of kaolin and NaOH was calcined at a temperature of 600 °C for 2 hours. The effect of synthesis parameters such as aging time and crystallization temperature was investigated in conventional methods. Besides that, the crystallization time was investigated in the alkali fusion method. Transformation of kaolin into metakaolin and synthetic products was characterized using X-ray diffraction (XRD), X-ray Fluorescence (XRF), Fourier Transform Infrared (FTIR) and Scanning Electron Microscopy (SEM). The results showed that the kaolin structure contained a lot of quartz. In the conventional method, the kaolin structure cannot be converted into metakaolin. The synthesis product obtained from this method is a mixture of sodalite and quartz. Whereas, in the alkali fusion method, kaolin can be converted into metakaolin and sodium silicate. The synthesis product obtained is a pure sodalite.