2.2. Characterization of adsorbents
The mineralogy of the AC and Mn3O4/AC was characterized by
X-ray diffraction (XRD) using a X-ray diffraction machine (D8
Advance, Bruker Corp., Ettlingen, Germany). The morphology and
elementary composition of the adsorbent surfaces were observed
using a scanning electron microscopy with energy dispersive X-ray
spectrometer (SEM–EDS, JSM-2701F, JEOL, Tokyo, Japan). Pore
structure was determined via nitrogen adsorption at 77 K using a
Micromeritics ASAP2010 analyzer installed in KBIS (Jeonju, Korea).
Surface area and pore volume were calculated using the Brunauer–
Emmett–Teller model and Barrett–Joyner–Halenda method.
2.3. Metal adsorption experiments
The adsorption characteristics of Pb(II) and Cu(II) onto the
prepared Mn3O4/AC were investigated in a batch experiment with
AC used as the control adsorbent. All chemicals and reagents used
were of analytical grade. A stock solution of heavy metals was
prepared by dissolving Pb(NO3)2 and Cu(NO3)2 in distilledwater to a
concentration of 1000 mg/L. Working solutions were prepared by
diluting the stock solution to specific concentrations. For the batch
test, 200 mLof the Pb(II) and Cu(II) solutionswas mixed with 0.2 g of
AC,Mn3O4 orMn3O4/AC and shaken in a shaking incubator for 48 h.