Optimization of Pb2+, Cd2+, Ni2+ and Ba2+ adsorption onto light expanded clay aggregate (LECA)

Abstract

The possibility of Pb2+, Cd2+, Ni2+ and Ba2+ ions removal from aqueous solution using light expanded clay aggregate (LECA) was investigated in this work. The central composite design (CCD) in response surface methodology (RSM) was used to optimize the operating parameters (adsorbent granulometry, absorption time and initial metal ions concentration) to reach the maximum ions removal in single and multi-elemental solutions. After optimization, the results shows that the removal efficiency decrease following the ion sequence Pb2+ > Ba2+ > Cd2+ > Ni2+ ions. The better efficiency (~95%) is observed for the Pb2+. The Langmuir and Freundlich isotherm models were applied to the equilibrium data at room temperature. The results revealed that data on LECA was very well fitted with Langmuir equations. The real interest of this work is to demonstrate that a simple material such as LECA can be used to remove extremely small levels of toxic metals, such as those found in drinking water. So our results could be the starting point for the development of a low-cost filtration system to remove toxic metals.