Removal of an anionic dye from aqueous solution by sepiolite using a full factorial experimental design

Abstract

Optimization of parameters by the classical batch adsorption method involves changing one independent variable and keeping the other factors constant in the same time. Classical method investigating effect of one variable at a time may be effective in some cases, but it consumes extra time and material. It requires large number of experimental trials to find out the effects. These limitations of the classical method can be eliminated by optimizing all the affecting parameters collectively by statistical experimental design. The statistical design experiments, designed to reduce the total number of experiments required, indicated that, within the selected conditions, all the parameters influenced at a significance level of 5%. In this study, batch adsorption experiments were carried out in order to evaluate the maximum adsorption conditions of the anionic dye reactive blue 220 (RB220) from aqueous solutions on sepiolite using a 2(3) full factorial design. The three factors were temperature, pH, and the ionic strength of the suspension. The optimization of the factors to obtain maximum adsorption was carried out by incorporating effect plots, normal probability plots, interaction plots, analysis of variance (ANOVA), Pareto charts, surface plots, and contour plots.