ABSTRACT
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Rice husk is a form of agricultural biomass that provides an abundant silicon source. Rice husks are widely burnt in agricultural fields in Nigeria especially in Abakilike, Nasarrawa, Gombe and Ekiti state because it is difficult to find other uses for them.
Impurity optimized amorphous silica is needed for many industrial applications. In this study, the possibility of producing high purity amorphous silica from rice husks has been pursued.
An integrated process was developed and practiced. That included pretreatment of rice husks using hot water solution, citric acid and hydrogen peroxide: Drying of the pretreated rice husks in an oven dryer at 120°C; Combustion of the dry treated husks in a muffle furnace at 880°C. Optimization of the combustion process was carried out within the temperature range of 500 to 880°C for time within the range of 1-4 hours using Response Surface Methodology (RSM) to maximize the percentage silica purity. Characterization of the optimized silica was carried out using XRF method of analysis for purity and crystallinity. The purity of silica was analysed in the following order, fit summary, the designed model ANOVA ,fit statistic, diagnostics, and model graph, which was basically shown by contours plots and Response Surface 3D plot, Normal plot of residuals and General summary of the report which comprises of run order, Actual value and predicted value using Respond surface methodology RSM package.
The organic components of the husks was also studied using weight loss analysis on both the As-received and pretreated rice husks to check for the effect of the pretreatment process on the removal of organic components.
This economic technology (process adapted) as applied to waste material also provides many benefits to the local agro industry. Thus this Research may be providing a low cost, high purity silica using a methodology that easily break loose the silica present in the rice husk from the influence of the cellulose, hemicelluloses and lignin polymeric bonds at lower temperature
