Comparison of Pb(II) Adsorption by Ground Granulated Blast-Furnace and Phosphorus Slags; Exploitation of RSM

One of the environmental issues is the release of heavy metal ions into groundwater, in which finding a cost-effective solution is crucial. In this study, lead as a toxic heavy metal cation was adsorbed by two low-cost industrial products of ground granulated blast-furnace slag (GGBFS) and phosphorus slag (PS). Both adsorbents were characterized by various analyses. The response surface methodology (RSM) based on the central composite design (CCD) method is employed to compare the performance of both adsorbents in Pb(II) removal from an aqueous solution. The experiment design was performed by considering three factors of initial Pb(II) concentration (20–100 mg.L), rotation rate (15–195 rpm), and adsorbent weight (0.1–2.1 g) at five levels. From the RSM predictions, the maximum adsorption capacity was obtained at 0.1 g, 100 mg.L, and 195 rpm. Based on the adsorption capacity data, GGBFS was more efficient than PS adsorbent in Pb(II) removal under the same conditions. The most influential parameter on the adsorption capacity was the adsorbent weight, and the other parameters had no significant effects. The influence of rotation rate could be observed only at low adsorbent weights. Two correlations are developed by taking into account the interaction effects between the studied parameters that fitted well the experimental data with R-values of 0.986 and 0.993 for GGBFS and PS, respectively. The statistical parameters and plots were also reported for the adsorption capacity of the both adsorbents.