Abstract
A composite of Fe3O4 nanoparticles and Eucalyptus camaldulensis (Ec) functionalized with ethylenediaminetetraacetic acid (EDTA) was characterized, and the efficacy of both adsorbents was investigated for the adsorption of lead ions (Pb2+) in batch studies. Fourier transform infrared spectra revealed successful modifications of the Fe3O4-Ec magnetic nanocomposite with EDTA and adsorption of Pb2+ ions on the surface of both adsorbents. A 15-min equilibrium contact time was estimated for optimal performance of both adsorbents due to the high adsorption capacity and the fast trend of removal efficiency upon immediate contact. Batch performance improved as the solution pH increased with the optimum value at 6.0 with maximum adsorption capacity and removal efficiency of 131 mg g(-1) and 99.5%, respectively. Both adsorbents exhibited a decreasing trend in adsorption capacity reaching to 78 mg g(-1) at 0.5 g, while the removal efficiency followed the opposite trend of a linear increase to almost 99% as the amount of adsorbent increased. The adsorption capacity increased as the initial Pb2+ concentration increased by 80 and 95 mg g(-1) for Fe3O4-Ec and Fe3O4-Ec + EDTA, while the removal efficiency decreased by more than 50% for both adsorbents in the studied range of Pb2+ (20-100 mg L-1). The Langmuir model better fitted the experimental data using both adsorbents with high coefficient of determination (R-2) values in addition to the Sips model, which proposes homogeneous as well as heterogeneous adsorption of Pb2+ on both adsorbents. Physical adsorption was proposed based on the estimated values of E (< 8 kJ mol(-1)) for both adsorbents, as estimated in the Dubinin-Radushkevich isotherm. A good fitting of the nonlinear pseudosecond-order model with R-2 values of 0.86 and 0.89 supports chemisorption as the controlling mechanism of adsorption. The estimated maximum adsorption capacities of Fe3O4-Ec revealed its potential for efficient removal of Pb2+ and encourages further work on catalytic (functionalized with EDTA) abatement of inorganic contaminants.