Pb(II) Adsorption Onto a Magnetic Composite of Activated Carbon and Superparamagnetic Fe3O4 Nanoparticles: Experimental and Modeling Study

Magnetic separation technology has been extensively used in the field of environmental problems, due to solving difficulties resulted from filtration and centrifuging. In this study, powder activated carbon (PAC) was magnetized by magnetite nanoparticles (Fe3O4@C) as an adsorbent for lead ions (Pb2+) from aqueous solution. The characteristics of the modified PAC were analyzed by scanning electron microscopy, transmission electron microscopy, X-ray diffractometry, Brunauer-Emmett-Teller surface area analysis, energy dispersive X-ray spectroscopy, and vibrating sample magnetometry. Batch adsorption experiments were conducted as a function of pH, contact time, adsorbent dosage and initial Pb2+ concentration, and solution temperature. The equilibrium isotherm and kinetic models were used to evaluate the fitness of the experimental data. The maximum mono-layer adsorption capacity of Pb2+ was 71.42 mg/g at 50°C. It could also be shown that the sorption isotherms were well described by the Langmuir equilibrium model. The kinetic of the adsorption process was found to follow the pseudo-second-order model expression. Thermodynamic studies indicated that the adsorption process was feasible, spontaneous, and endothermic. Desorption experiments exhibited that the Fe3O4@C had a good potential in regard to regeneration and reusability and is easily regenerated by HCl solution. The proposed adsorption process can be a promising technique for Pb2+ removal from aqueous solutions and to be used in full-scale and industrial applications.