Adsorption of the Pb2+ ions by the Fe3O4@GMA-AAm nanocomposite was measured from batch adsorption experiments by mixing 10 mg of adsorbent with an aqueous solution containing a predetermined concentration of Pb2+ ions (50 mL). The mixture was shaken at 200 rpm to reach equilibrium. After a specified time, the solid and liquid were separated by external magnet and the concentrations of Pb2+ ions were measured by AAS. To find the optimized pH in adsorption of Pb2+ ions the effect of the pH was studied. The initial pH of the solutions was adjusted in the range of 2.0 –7.0 by adding 0.1N HCl or 0.1N NaOH solution at 25 ◦C. The effect of the dosage of adsorbent on the adsorption was also determined with different nanocomposites …show more content…
According to the experimental results obtained, a mechanism which can be proposed for the adsorption of Pb2+ ions on the Fe3O4@GMA-AAm surface was shown in scheme 3.
The equilibrium adsorption capacity (qe) (mg g−1) for Pb2+ ions was calculated according to the following equation: ( Eq.1) where C0 and Ce (mg L−1) are respectively the initial and equilibrium Pb2+ ions aqueous concentrations. V is the volume (mL) of Pb2+ ions aqueous solution; m is the mass (mg) of adsorbents used in the experiment. The removal percentage of metal ions was calculated using the following equation: ( Eq.2)
(Scheme 3)
3.3. Adsorption study of the Fe3O4@GMA-AAm …show more content…
Figure 12A shows the contact time vs. the removal percentage curves. It can be observed that the uptake of Pb2+ ions was very rapid and a large amount of this toxic ion was removed within a few minutes (2 min). The fast adsorption process may be the result of the fast kinetics of active sites on the surface of the synthesized composite in the adsorption of pb2+ ions along with a large number of accessible active adsorption sites on the uncovered absorbent surface [36]. After this time there was no significant change in terms of the amount of adsorption due to the saturation of the active sites on the absorbent surface. Therefore the equilibrium time for the synthesized nanocomposite was found to be about 2