A novel environmentally friendly super-paramagnetic nano composite based on cross-linked poly (N-vinylpyrrolidone-co-maleic anhydride) (PNVPMA) was successfully prepared by simultaneous reaction of the PNVPMA copolymer with 3-aminobenzoic acid (3ABA), as a modifying agent, and ethylenediamine, as a cross linking agent, in the presence of Fe3O4 nano particles and eggshell. The prepared materials were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Vibrating sample magnetometer (VSM) was used to measure the magnetic property of nano composite as a function of magnetic field. The uptakes of Pb (II) and Cd (II) on the nano composite were studied in a batch system. The influences of various factors including pH of solution, nano composite dosage, agitation time, and initial concentrations of Pb (II) and Cd (II) were also investigated. The maximum adsorption capacities (Qmax) of Pb (II) and Cd (II) on the nano composite under the certain experimental conditions were 312.5 mg/g and 32.78 mg/g, respectively. The results showed that the experimental data of the Pb (II) and Cd (II) adsorption on the nano composite were in agreement with the Langmuir adsorption isotherm and second-order kinetic equations. The negative values of ΔG° for the adsorption of both Pb (II) and Cd (II) on the synthesized nano composite endorse that the adsorption processes are spontaneous and thermodynamically favorable. On the other hand, the positive values of ΔH° support the endothermic physical adsorption process.
