Preparation of analcime from local kaolin and rice husk ash: Fid-Bau Portal

Preparation of analcime from local kaolin and rice husk ash

Atta, A.Y. / Jibril, B.Y. / Aderemi, B.O. / Adefila, S.S.

Abstract Analcime zeolite was synthesized using a hydrothermal technique with rice husk ash and metakaolin as sources of silica and alumina respectively. Both the raw materials and the final product were characterized using XRD, FTIR, SEM and atomic absorption spectroscopy. XRD diffractogram of the rice husk exhibited α-quartz as a dominant and critobalite as a minor component. Metakaolin consisted of alumina, with minor amounts of α-quartz. Analcime was obtained after 72h aging and 24h reaction time at temperature of 180°C. Longer reaction time led to a decrease in the amount of analcime phase with corresponding increase in zeolite-p. SEM of the analcime crystals showed formation of trapezohedral morphology of sizes ranging from 15 to 25μm. The analcime was tested in the adsorption of phenol from its aqueous solutions (50–400ppm). Among the adsorption isotherms tested, the Langmuir model was found to give better representation of the data. The ultimate amount of phenol adsorbed on analcime (12.5mg/g) was lower compared with a commercial zeolite (33.1mg/g) used as reference. However, in terms of adsorption per surface area, the analcime (3.88mg/m²) exhibited better performance than the other sample (0.01mg/m²). The value of the constant related to free energy of adsorption in the Langmuir model was used to evaluate a dimensionless equilibrium parameter, RL. At high phenol concentrations (100–400ppm), the RL values for the commercial sample (0.73–0.40) were higher than for analcime (0.50–0.20). The results show that the readily available raw materials could be used to prepare analcime zeolite with a good and favourable adsorptive capacity.

Graphical abstract Figure 6 SEM micrographs of analcime samples: A (scale bar 50μm) and B (scale bar 10μm). Display Omitted Highlights ► Analcime zeolite was synthesized using local clays sources of silica and alumina. ► Rice husk ash and metakaolin were used as sources of silica and alumina. ► Reaction time is important in determining the amount of the analcime phase. ► The analcime crystals formed trapezohedral morphology with size of 15 to 25μm. ► The samples exhibited high adsorptive capacity for the removal of aqueous phenol.