Removal of lead (II) from aqueous solution by batch adsorption on various inexpensive adsorbents using experimental design

AbstractThis study focuses on adsorption of lead (II) using various inexpensive adsorbents, such as dried activated sludge, diatomite, and sepiolite, through the batch process. The data were evaluated using three types of isotherm models to determine the design parameters. Additionally, the adsorption kinetics was analyzed using first- and second-order kinetics. The regression coefficient (R2) quantitatively evaluates the correlation between the experimental data and the predicted responses. The Box–Behnken design of three factors at three levels was used to determine the important parameters affecting the adsorption of lead (II) by different adsorbents and the results showed that pH, initial concentration, and type of adsorbent in these experiments are the important factors. The Freundlich isotherm model fits for all adsorbents, as indicated by the R2 values of 0.992, 0.997, and 0.997 for Pb2+ adsorption onto dried activated sludge, diatomite, and sepiolite at pH 3, respectively. The adsorption capacity ...