Lead Adsorption on Magnetite at 200°C

Abstract Lead uptake on magnetite (Fe3O4) has been quantitatively evaluated by equilibrium adsorption isotherms at 200°C and pH of 8.5 for 2 h contact time with [Pb2+] ranging from 5 ppm to 175 ppm. The adsorption data has been fitted to Langmuir and Freundlich models. The maximum adsorption capacity of magnetite as a lead adsorbent was 90.9 mg/g and 4.59 mg/g for the Langmuir and Freundlich models, respectively. A pH-independent Pb2+ sorption on magnetite in the pH range of 3.3 to 10.3 was observed, possibly suggesting Pb2+ sorption is due to permanent charges through weak electrostatic, nonspecific attraction where cations are sorbed on the cation exchange sites rather than pH-dependent sorption through surface hydroxyl/surface complexation. Inductively coupled plasma-optical emission spectroscopy (ICP-OES), Fourier transform infrared spectrophotometry (FTIR), and x-ray diffraction (XRD) techniques were used to study the mechanism of Pb2+ adsorption on magnetite. XRD results indicated a monotonic increa...