Application of Rsm for Pb(Ii) and Cu(Ii) Adsorption by Bentonite Enriched With -Sh Groups and a Binary System Study

Abstract

The aim of this study is to remove Pb(II) and Cu(II) ions in binary and single solutions with bentonite enriched with -SH groups (BSH) and to optimize the adsorption conditions by using Response Surface Methodology (RSM). Some parameters (initial pH, initial metal concentration, adsorbent dosage and contact time) affecting the adsorption were optimized with Central Composite Design (CCD) under RSM. Optimum values for removal of Pb(II) and Cu(II) by BSH were obtained from the quadratic model generated from CCD. The optimal points for initial pH, initial concentration, adsorbent dosage and contact time obtained by the numerical analysis were 5.10, 32.98 mg/L, 146 mg and 146.01 min. for Pb(II), while these values were 4.52, 37.9 mg/L, 152.3 mg and 146.12 min. for Cu(II), respectively. At the optimum values, maximum Pb(II) and Cu(II) removal were obtained as 95.05% and 91.4%, respectively. Adsorption data for both metal ions were observed to conform with the pseudo-second order kinetic model and Freundlich isotherm model equation. In addition, owing to observation of the competitive effect in the removal of Pb(II) and Cu(II) ions by BSH, some binary system experiments were carried out under optimum conditions obtained for the single system. The selectivity adsorption order of BSH was determined as Pb(II) > Cu(II). Considering all this, it was shown that BSH has great potential applications for the removal of heavy metal impurities from aqueous solutions.