Modelling of Adsorption of Zinc and Silver Ions on Analcime and Modified Analcime Zeolites Using Central Composite Design

In this study, Response Surface Methodology (RSM) using Central Composite Design (CCD) was employed to optimize the conditions of independent variables (adsorption time and ion solution concentration) for the removal of Zinc (II) and Ag ions from the aqueous solutions using analcime and modified analcime zeolites (Fe-ANA and Ni-ANA) as efficient and low cost adsorbent. The operation conditions were contact time of 1-13 h and ion concentration of 25-250 ppm at ambient temperature. Under these conditions, the response (the adsorption capacity of zinc (II) and Ag ions) was fitted by a quadratic polynomial regression model and linear model analysis in five-level-two-factor CCD using Design Expert software. The optimal conditions (high removal efficiency) for zinc (II) and Ag+ adsorption were achieved. The analysis of variance demonstrated that ion concentration effect was found to be significant in the adsorption process. Moreover, actual and predicted response plot of ion adsorption in zeolites were investigated.