Removal of congo red by using eggshells as adsorbent

Dyes are usually present in trace quantities in the treated effluents of many industries. The effectiveness of adsorption for dye removal from wastewaters has made it an ideal alternative to other costly treatment methods. Batch adsorption studies were conducted for the adsorption of Congo red dye on waste eggshells powder by varying the adsorption parameters such as pH (2-8), adsorbent dose (0.2- 0.8 g) and contact time (5-20 minutes). A 23 full factorial central composite design
(CCD) combined with response surface methodology (RSM) was employed to evaluate the effects and interactions effects of different adsorption parameters as well as for optimization Congo red removal using eggshells as adsorbent. The significant of independent variables and their interactions were tested by the analysis of variance (ANOVA). The analysis of variance (ANOVA) indicated that a second-order polynomial regression equation was the most appropriate for fitting the experimental data. Results revealed that coefficient of correlation (R²) between the predicted and experimental responses are 0.9060. The optimum conditions for Congo red adsorption by eggshells were found to be pH 8, 0.8 grams and 20 minutes, respectively and under these conditions the removal efficiency was found to be 97.35%.