Preparation of Activated Carbon from Date Stones:Optimization on Removal of Indigo Carmine from Aqueous Solution Using a two-Level Full Factorial Design

In this work date stones (SD), agriculture wastes, available in large quantity in Tunisia, were used to prepare a low cost activated carbon (DSAC) for removing Indigo Carmine (IC) from aqueous solution. Chemical activation method using ZnCl2 was employed for the preparation of the DSAC. A 2-level full factorial design (FFD) was applied to correlate the preparation variables (activation temperature, activation time and impregnation ratio) to the removal of IC from aqueous solution. The influence of the studied parameters on the IC adsorption was also investigated by using the analysis of variance (ANOVA) to identify the significant variables. The results obtained showed that the optimum conditions for preparing activated carbon from DS for IC adsorption were activation temperature of 700°C, activation time of 120 min and impregnation ratio of 2:1 (Acid / DS, wt basis) which resulted in 298.1 mg/g adsorption capacity of IC from aqueous solution at pH 6.0. It was observed that experimental values obtained were in good agreement with the values predicted by the model. The DSAC seems to be a good adsorbent for the removal of anionic dyes in particular indigo carmine from wastewaters. Keywords—Activated carbon, Full factorial design, Analysis of variance, Optimization, Date stones, Indigo carmine removal,