Use of response factorial design for process optimization of basic dye adsorption onto activated carbon derived from Persea species

Full factorial design is a powerful and efficient mathematical approach widely applied in the optimization of response. The important parameters which affect the removal efficiency of methylene blue such temperature, initial pH of the solution, concentration and adsorbent dosage were optimized. They coded as A, B, C and D, consecutively, and were investigated at two levels (+ 1 and − 1). A linear mathematical model representing the influence of the different variables and their interactions was obtained. Main effect, Normal probability plot of residuals, analysis of variance (ANOVA), surface plots, and contour plots were used to study the effects and interaction effects between operational parameters.