Removal of Pb(II) from Water Using (Fe3O4/Ni/NixB) Magnetic Nanocomposites, Carob (Ceratonia siliqua) or Grape Seeds (Vitis vinifera)

A novel magnetic adsorbent Fe 3 O 4 /Ni/Ni x B nanocomposite was synthesised and used for the removal of Pb(II) from water. The nanocomposite effectively absorbs Pb(II), and because the adsorbent is magnetic, it is easily separated from the solution. In addition, carob and grape seeds, which are sustainable materials, are also used for the removal of Pb(II) for the first time in the literature. Characterisation of the adsorbents was performed using scanning electron microscopy combined with energy dispersive X-Ray spectroscopy (SEM−EDX). The effect of pH on the adsorption efficiency of Pb(II) was investigated. The optimum adsorbent doses were determined as 2.0 g/L for the Fe 3 O 4 /Ni/Ni x B nanocomposite and 4.0 g/L for the carob and the grape seeds. Three commonly used isotherm models: Langmuir, Freundlich and Dubinin–Radushkevich were applied to the experimental data. The batch adsorption equilibrium data of the three adsorbents fitted well to Langmuir isotherms. The maximum capacities for the adsorption of Pb(II) were determined to be 119.0, 25.3 and 24.4 mg/g for the Fe 3 O 4 /Ni/Ni x B nanocomposite, the carob and the grape seeds, respectively. The dimensionless separation factor (R L ) values calculated from the Langmuir isotherm were varied from 0.08 to 1 for three adsorbents. These results demonstrate that the adsorption of Pb(II) on all the adsorbents is favourable. The pseudo-first order, the pseudo-second order and the Weber−Morris intraparticle diffusion kinetic models were used for the identification of the adsorption kinetics of Pb(II) and the correlations of adsorbed Pb(II) with time. The kinetic data is well described with the pseudo-second order kinetic model for all the adsorbents, which indicates that chemisorption plays a dominant role. The adsorption study using a column was successfully applied to real tap water and waste water samples. Also a spiked study (1, 10, 100 mg/L Pb(II)) was also conducted on water samples. As a result, Fe 3 O 4 /Ni/Ni x B nanocomposite, the carob and the grape seeds are efficient adsorbents for the removal of Pb(II) from the water samples.