Removal of Toxic Heavy Metals Lead and Mercury from Aqueous Medium by Adsorption onto Acid Functionalized-Nanoporous Carbon/MnO2 Nano Composite

Acid functionalized-Nanoporous carbon/MnO2 nanocomposite was prepared from grass clippings as carbon precursor and used for removal of Pb(II) and Hg(II) from aqueous medium. The adsorption study of Pb(II) and Hg(II) on the surface of Af-NPC/MnO2 was carried out with respect to factors such as pH, contact time and initial concentration. The kinetic study shows that the process of removal of these metal ions follow pseudo second order kinetics and the experimental equilibrium data fitted better in Langmuir isotherm model with maximum monolayer adsorption capacities of 117.64 mg/g and 90.09 mg/g for Pb(II) and Hg(II) respectively. The process of adsorption was found to be very fast compared to other adsorbents from literature. The mechanism of adsorption is also proposed based on experimental results. The results of this study indicated that AfNPC/MnO2 is an efficient adsorbent for removal of both Pb(II) and Hg(II) from aqueous medium. It was also observed that the composite was more selective for Pb(II) comparing to Hg(II) in a binary mixture.