Magnetic Activated Carbon for Efficient Removal of Pb(II) from Aqueous Solution

In this work, magnetic based activated carbon (MPSAC) was prepared via a simple one-step method in the presence of K2CO3 and Fe3O4 and further examined as an adsorbent for the removal of Pb(II). MPSAC possessed a well-developed porosity structure with a high surface area of 1,219m(2)/g and contained rich carboxylic functional groups on the surface. It can be separated easily from a suspended system. The pH(IEP) value of MPSAC was notably lower than the pH(PZC), suggesting that the negatively charged surface was largely distributed in the external area. Batch adsorption experiments were carried out by varying the initial pH, contact time, adsorbent dosage, initial Pb(II) concentration, and temperature of solution. Results show that adsorption of Pb(II) on MPSAC was dependent on contact time, solution pH, adsorbent dosage, initial Pb(II) concentration, and temperature, especially solution pH having strong effects at pH 2-4. Adsorption kinetic and equilibrium data were well described by the pseudo-second-order model and Langmuir isotherm with the maximum monolayer adsorption amounts of 146.20, 152.67, and 158.73mg/g at 293, 303, and 313K, respectively. Intra-particle diffusion mechanism was partially responsible for the adsorption. The thermodynamic study indicated that the adsorption was a spontaneous and endothermic process. Competitive adsorption showed that MPSAC has a good adsorption selectivity for removal of Pb(II) ion.