Synthesis of Zeolites from Rice Husk Ash for Removal of Dyes in Wastewater

Abstract

Rice husk is an agricultural waste which contains high amount of silica. This silica can be extracted from rice husk by burning at higher temperatures. Therefore, rice husk ash (RHA) can be used as the silica source when synthesizing zeolites. Zeolites are three-dimensional microporous aluminosilicate which are widely used in industrial applications. In this study, potential of using zeolites synthesized from RHA for the adsorption of dye in polluted water was tested. RHA was obtained by burning rice husk at 700 °C and zeolites were synthesized by using RHA and sodium aluminate in alkali media. Synthesized zeolites were yielded as 75.4% (w/w) and classified as Zeolite A (LTA) based on the XRD analysis. Adsorption capacity and adsorption rate of synthesized zeolites were tested for Methylene Blue (MB) solution through equilibrium and kinetic studies. The adsorption of MB onto RHA was also studied for comparison. Langmuir model and Pseudo second order kinetic model were well fitted with the experimental data with higher coefficient of determination. The monolayer adsorption capacities of the synthesized zeolites and RHA were 16.89 mg/g, 17.42 mg/g and 12.19 mg/g respectively. Synthesized zeolites show higher adsorption capacity than the RHA revealing that Zeolite A synthesized using RHA can use to adsorb dye in polluted water. This study also can be extended to obtain the best zeolite which has a greater adsorption capacity by adjusting synthesis conditions.