Mathematical Modeling Using Full Factorial Design Applied in the Adsorption of Dye Basic Blue 9 from Synthetic Aqueous Solutions onto Oryza Sativa Husk-Derived Nano-Silica-Smectic Clay Composite

This study focuses on utilizing Oryza sativa husk (rice husk) to produce a nanosilica-doped smectitic clay (Os-Sm) for the adsorption of Basic Blue 9 from aqueous solutions. Response surface methodology was employed to investigate the impact of dye concentration (10—30 mg/L), initial pH (8—11), and contact time (0—100 min). The regression model exhibited a remarkable predictive capability, accounting for over 99% of the targeted response variation within the specified ranges of the factors (R² = 99.98%) with a 95% confidence level. The analysis of variance confirmed the significance and accuracy of the mathematical model, with F-values (1539.08 > > 1) and p-values (< 0.05) indicating the statistical significance of almost all factors within the studied ranges. These findings were supported by factorial, surfaces, and contours plots. Furthermore, the pseudo-second-order kinetic and Langmuir models demonstrated excellent fitting to the experimental data, with determination coefficients of 0.976 and 0.965, respectively. At optimal conditions (30 mg/L, pH 11, t > 50 min, and adsorbent dose of 0.5 g/L), approximately 96.33% of the dye was successfully removed. Os-Sm emerges as a promising and efficient alternative for Basic Blue 9 removal in aqueous solutions.