Optimization of Congo red dye removal by eggshells using response surface methodology

Abstract

Compared to other costly treatment methods, the effectiveness of adsorption process as the wastewater treatment for the removal of dye has made it as an ideal alternative method. Batch adsorption studies were conducted for the adsorption of Congo red dye using eggshells by varying the adsorption process parameters such as pH (2-8), adsorbent dose (0.2-0.8 g) and contact time (5-20 minutes). Central composite design (CCD) combined with response surface methodology (RSM) was employed to study the interactions effects of adsorption process parameters as well as for optimization of congo red removal using eggshells as adsorbent. The significant of independent variables and their interactions were tested using analysis of variance (ANOVA). ANOVA indicated that a second-order polynomial regression equation was the most appropriate model for fitting the experimental data. Results revealed that coefficient of correlation (R2) for the quadratic model are 0.9060. The optimum conditions for congo red adsorption by eggshells were found to be at pH 8, 0.8 g and 20 minutes, respectively and the removal efficiency was found to be 97.35%.