1. Introduction:
Currently, there is a continuously growing necessity worldwide for wastewater treatment. The water contamination is one of the major perilous issues that is facing the world today. According to The United Nations estimation over 1.7 million deaths all around the world annually, are arising from the utilization of unhealty water [Health Organization, 2015]. The heavy metals is one of the most hazard chemical compounts existed in the aquatic environmental, as a result of expeditious development of industrialzation and agricultural activities. Causing a destructive influence in the ecosystem when they discharged into the clean water, due to their toxicity, non-biodegradable characteristics and their accumulative effect [Gcina Mamba and Ajay Mishra, 2016].
lead (Pb2+), as a one of toxic heavy metals has a bad effect on the blood and the nervous system [Malhat, 2011], can found in waste-water through discharge of various industrial activities like coating, automotive, aeronautical, steel industries and battery manufacturing [A. Selatnia et al, 2004]. Although the produced concentrations from industrial sectors are too low, it difficult to be treatment by conventional methods such as chemical precipitation that leads to toxic sludge [Ahalya, N.; et al, 2003]. Otherwise some processes such as solvent extraction are not appropriate for effluents containing less than 1 g/l of the removable heavy metal. Furthermore, ion exchange methods are costly due to the expensive of the synthetic resins. Among various available treatment techniques that were found for the removal of toxic metals from aquatic environment. Adsorption technique appears as an effective and inexpensive method for the removal of toxic heavy metals from wastewater [A.Z.M. Badruddoza et al 2013]
Many of researchers were examined various adsorbents materials for heavy metal removals such as activated carbons, zeolites, clays, and polymeric materials in wastewater treatment [Crini, 2005], however some of these materials have limited applications in practical wastewater treatment, due to their low surface area and difficult separation from the liquid phase. The use of Magnetic nanoparticles that are usually involve magnetic elements, such as iron, nickel, cobalt and their respective oxides [V.I. Shubayev et al., 2009] appear as a promising material to be more helpful in water purification due to its unique Magnetic properties and the low preparation cost. On the other hand, Magnetic nanoparticles (MNPs) have a relatively high surface area and they can separate and manipulate under the influence of an external magnetic field by easy way.
Recently, superparamagnetic nanoparticles (SPIONs) have wide rang of application for different purposes such as catalysis [ Lin S, et al 2013], supercapacitors [ Du X, et al., 2009], lithium ion batteries [ Koo B, et al 2012]. Especially, nanoparticles of iron oxide such as Fe3O4 and γ -Fe2O3 are reported to be applicable in biology and medicine fields as a material for use in drug delivery systems, magnetic resonance imaging, and cancer therapy [T. Neuberger, et al., 2005. D. Portet et al., 2001 and A. Ito et al., (2005)]. Moreover, it has efficacious application as effective and economical adsorbent for fast removal and recovery of heavy metal ions from contaminated water [Firoozeh Foroughi et al., 2015]. Firoozeh Foroughi et al. were used CoFe2O4–hydroxyapatite composite as an nanoadsorbent for elimination of Zn(II) from aquatic environmental within 60 min. [Firoozeh Foroughi et al., 2015]. Liu et al. were succssful prepared Fe3O4 nanoparticles coated with humic acid (HA) by the coprecipitation method for the removal of toxic heavy metals such as Hg(II), Pb(II), Cd(II), and Cu(II) from waste water [J.F. Liu, et al., 2008]. Nassar found that the adsorption effeicency of iron oxide nanoparticles for removing lead ions was 36.0 mg g−1, that is posses higher effeicency than other available adsorbents [N. N. Nassar,2010].
Several methods of preparation have been reported for obtainted MNPs through various chemical methods like as coprecipitation, hydrothermal method, sol-gel, thermal decomposition, microemulsion, and colloidal chemistry method [REF.]. In addition to these methods, electrochemical synthesis can be applied for the preparation of MNPs
In recent years, the majority of researches have been focused on the enhancement of the chemical and physical properties of magnetic nanoparticles (MNPs) using shell protective coating layer of organic polymeric material, such as polystyrene, polyaniline, polymethyl methacrylate and polyacrylamide, as well as inorganic materials like silica, alumina, gold [Juliana C et al., 2011] to be more adequate for different applications. Among different materials used as shells, carbon which is chemically more stable than polymeric organosilicones [A. V. Bychkova et al., 2012] and prevents chemical corrosion of magnetic core materials. otherwise, surface modificationacts improve the stability of the MNPs under acidic medium. Different approaches have been applied for the preparation of carbon coatings, for example, electric arc discharge, catalytic pyrolysis of organic compounds, and the hydrothermal methods [14]. Carbon coated iron oxide nancomposites are favorable for industrial sector wastewater treatment, due to their low cost, strong adsorption capacity, easy separation and regeneration. (Piao Xu , et al., 2012).
superparamagnetic iron oxide (SPIO) coated carbon nanocomposites were successfully prepared by in situ reduction-carbonization via hydrothermal method, in which the Iron (III) chloride and glucose were used as the starting materials [Xuan S et al., 2007]. Wang et al. demonstrated that ferrocene can be utilized immediately as the single reactant to gain superparamagnetic iron oxide /Carbon core shell nanocomposites [Wang H, et al. 2010]. Ning Luo, et al were controllably synthesized carbon coated iron nanoparticles by detonation decomposition of urea nitrate metal complex explosives [Ning Luo, et al., 2012].
The main target of this research is synthesized Fe3O4/C nanomagnetic composite via co-precipitation process followed up by hydrothermal method. Simultaneously, employed the parepared nanocomposite as a adsorbent for removing of lead (Pd+2) pollutant from waste water, as well as reused it as economic and effective treatment adsorbent for water purification. The phase composition, morphology and grain size, functional groups, morphology and distribution of the elements existed in the synthesized Fe3O4/C were examined using X-ray diffractometry (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Scan electon microscope (SEM) attached with energy dispersive spectrometry (EDS), respectively. As well as, the magnetic properties were measured using a vibrating sample magnetometer (VSM) at room temperature. On the other hand, the specific surface area determend by BET. As for the performance test, the adsorption capacity (Qm) of Pb2+ adsorption onto nanocomposite calculated from the Langmuir isotherm. furthermore, Parameters that has impact on the adsorption such as pH, adsorbent dose, contact time and concentration of lead ions were examined.