Synthesis of Zeolite by Thermal Treatment Using Locally Sourced Ugwaka Clay (Black Clay)

Abstract

Application of response surface methodology in zeolite synthesis from ugwaka clay has been demonstrated.  In this study, optimization of synthetic zeolite production was carried out. Process variables such as reaction time, sodium hydroxide concentration, and calcination temperature were optimized using Box-Behnken design. Raw ugwaka clay was treated with distilled water and sodium hexametaphosphate to remove the impurities usually associated with natural clay and induce sedimentation. The clay undergoes metakaolinization at 700  for 2hours. X-ray Florescence (XRF), Fourier Transform Infrared (FTIR) and Scanning Electron Microscope (SEM) were used in sample characterization. XRF analysis of raw ugwaka clay gave silica-alumina ratio of 1.705 which falls within the specifications for the synthesis of zeolite. The reaction time, sodium hydroxide concentration and calcination temperature were varied between 1.5-2.5 hours, 600-900  and 1-4M respectively. A quadratic model was developed and was used for the prediction of zeolite yield. Optimization of the process resulted in the reaction time of 2 hours, sodium hydroxide concentration of 2.5 M, and calcination temperature of 800 . Optimum conditions were validated at the model desirability of 1. The experimental value of 92.03wt% yield of zeolite with 0.895% error was obtained. Comparison of the zeolite produced with commercially available zeolite showed that it has good properties to be used in water treatment.