Applying Fe3O4-MoS2-chitosan nanocomposite to preconcentrate heavy metals from dairy products prior quantifying by FAAS

Abstract

A magnetic solid phase extraction method is presented to preconcentrate Pb(II), Cd(II), Ni(II) and Zn(II) simultaneously. The adsorbent (mMoS2-CS), consisting of Fe3O4, MoS2 and chitosan (CS), was prepared facile and fast with consumption of environmentally friendly materials. X-ray diffraction shows pure crystallinity of the products. The morphologies were pictured by scanning electron microscopy and transmission electron microscopy, confirming homogeneous distribution of Fe3O4 and nanosheets of MoS2. The spectra of Fourier transform infrared spectroscopy confirmed strong interactions between components and locating CS successfully. Strong magnetic properties and high surface area were investigated by an alternating gradient force magnetometer and Brunauer–Emmett–Teller, respectively. According to the mentioned features, mMoS2-CS could be introduced as a highly efficient adsorbent to preconcentrate heavy metals. The preconcentration conditions of Pb(II), Cd(II), Ni(II) and Zn(II) were optimized as pH of 5.0\u2009±\u20090.5, adsorbent amount of 20.0 mg, adsorption time of 15 min, eluent of HNO3 (5 mL, 1.0 mol L−1) and desorption time of 3 min. Flame atomic adsorption spectroscopy quantified the concentrations. Limit of detection, limit of quantification, relative standard deviation, enhancement factor, reusability, durability, selectivity and effect of interference ions were reported. Adsorption isotherm, adsorption kinetic and adsorption thermodynamic were studied to better understand the adsorption mechanisms. The results of heavy metals determinations in dairy samples showed successful performance of mMoS2-CS in real samples.