Effect of Temperature on the Synthesis of Zeolite X from Ahoko Nigerian Kaolin Using Novel Metakaolinization Technique

Zeolite X was synthesized successfully from kaolin using a novel metakaolinization technique. The first step involves refining the raw kaolin sample, followed by metakaolinization. This was done after determining the metakaolinization temperature of Ahoko Nigerian kaolin (ANK) as 600 degrees C using in situ X-ray diffraction (XRD) and simultaneous thermal analysis (STA). A new method for the production of metakaolin was investigated in this work. Metakaolin was obtained after 50 min of exposure at 600 degrees C. The metakaolin produced was used to synthesize zeolite X using the hydrothermal method. Highly crystalline zeolite X was not obtained until the crystallization temperature of 80 degrees C was attained, with aging time and crystallization time fixed at 24 h and 6 h respectively. Zeolite formation increases with increase in crystallization temperature as evident from the increase in the intensity of diffraction peaks. An increase in temperature beyond 100 degrees C leads to a remarkable decrease in the reflectivity of zeolite X, with formation of a completely new zeolitic phase recognized as sodalite, which was formed at 200 degrees C. Finally, the ion exchange behavior of the synthesized zeolite X obtained at 100 degrees C was investigated. The removal of metal ions from synthetic solutions at an initial concentration of 200 ppm was studied using inductively coupled plasma-optical emission spectroscopy (ICP-OES). The cation exchange capacity (CEC) was calculated as 2.31 meq g(-1). Removal efficiency was determined at varying contact times with an optimum removal time of 30 min for all the metal ions, except Ni+, with an optimum time of 4 h. It was observed that the as-synthesized zeolite X had a strong ion exchange affinity with the metal ions studied.