The adsorption of the Pb+2 from the aqueous solution was carried out via a batch technique and at a fixed solution pH (5.5). At the first place, the adsorption isotherm had based on studying the change of the Pb+2 concentrations against the operational time at constant temperature of 25 °C. Time intervals; particularly 10-120 min were applied at this stage. Initial Pb+2 concentration of 370 mg/L and adsorbent/solution ratio of 5 g/L were also used. For each time interval, 0.1 g of the adsorbent was added to 20 mL of the Pb+2 solutions in a 50 mL auto-clavable test tube which was then stirred at 150 rpm with a shaking thermostat. At the completion of each time interval, the tube was picked out from the shaker and the adsorbent was separated from the solution by the centrifugation at 3000 rpm for 15 min. The solutions which contained the remains of the Pb+2 after the adsorption process were subjected to analysis through the AAS technique to determine the adsorbed amount of the Pb+2 through the difference between its initial (Co) and equilibrium (Ce) concentrations. Spectrophotometer- Zeenit model 700 Panalytikajena, manufactured in Germany was the instrument which was utilized for the determination of the lead removal percentage.
The effect of the operating temperature on the efficiency of the Pb+2 adsorption by the Co Mo LDH was then studied at (298, 308 and 318 K) and under the equilibrium time, as obtained from the prior stage. All the aforementioned procedures and conditions, as described in the previous stage, had been similarly repeated in this stage of testing. Finally, the effect of the Pb+2 initial concentrations on the adsorption capability of the Co Mo LDH was also examined. Different Pb+2 concentrations were applied, particularly in the range between 370 and 2000 mg/L. This stage was carried out at 298 K while following the same experimental actions and parameters, as stated in the first stage of the adsorption investigations.