Mathematical Modelling using Full Factorial Design in Response Surface Methodology Applied in the Adsorptive Removal of Dye Basic Blue 9 From Synthetic Aqueous Solutions Onto Oryza Sativa Husk-derived Nano-silica Doped Smectic Clay

Abstract

The present work aimed to use Oryza sativa husk (rice husk) in the fabrication of a nanosilica-doped smectic clay for the adsorption of Basic Blue 9 in synthetic aqueous solutions. Response surface methodology was used to evaluate the effects of the considered factors namely, initial dye concentration (10 - 30 mg/L), initial pH (8 - 11), and contact time (0 - 100 min) on the adsorption process. The regression model was found to be able to predict more than 99 % of the targeted response variation in the studied range (R2 = 99.98 %) based on 95% confidence. The analysis of variance proved the significance and the accuracy of the mathematical model. The F-values (1539.08) and p-values (< 0.05) generated by Minitab21 Sofware©, indicating that almost all the independent factors were statistically significant in the studied ranges. Based on the coefficients, initial dye concentration was more influential, followed by pH and contact time. Also, concentration x pH interaction was more effective followed by concentration x contact time. The pH x contact time interaction was very weak and those results were in accordance with factorial, surfaces, and contours plots. The pseudo-second-order kinetic and Langmuir models fitted well to the experimental data with determination coefficients of 0.976 and 0.965 respectively. Under the optimal conditions (30 mg/L, pH 11, t > 50 min; and adsorbent dose of 0.5 g/L, almost 96.33% of the dye was removed. Os-sm is thus an interesting and effective alternative for the removal of BB9 in aqueous solutions.