Batch sorption, a technique commonly used to obtain **data** on the removal efficiency of a given sorbent under static conditions, was selected as an appropriate technique in the current study. Polypropylene tubes containing 20 mL of metal solution and 3 g/L of limestone powder from the \210 lm-sized samples (S or Z) were shaken at 200 rpm at 25°C for 60 min to reach equilibrium. In single, binary and multi-element systems, 10 mg/L of each metal was used as an initial concentration to achieve similar concentration for all systems (molar concentration: [Pb] = 4.82 9 10 -5 mol/L, [Cd] = 8.89 9 10 -5 mol/L, [Cu] = 1.57 9 10 -4 mol/L and [Zn] = 1.52 9 10 -4 mol/L). For instance, in quadruple system, 5 mL of each metal stock solution (1,000 mg/L) were introduced in 500 mL volumetric flask and then diluted with UPW to obtain an initial concentration of 10 mg/L for each metal. The initial pH of the solution was adjusted to 6 with 0.1 M HCl and 0.1 M NaOH prior to mixing with limestone powder (Sdiri et al. 2012b). After shaking, 10 mL of supernatant were withdrawn and filtered through a 0.2 lm syringe-driven filter (Millex-LG, PTFE, Millipore Corp., Ireland). After the reaction, the sample solutions were stored at 4°C until analysis for Pb 2? , Cd 2? , Cu 2? and Zn 2? with an ICP-AES instrument, Optima 7300 DV series (PerkinElmer Inc., Tokyo, Japan). The amount of a metal removed from the solution was calculated as the difference between initial and final concentrations. The same experimental conditions were maintained for mixed systems (i.e., binary, ternary and quadruple mixtures). All experiments were run in triplicate.