Reverse Precipitation Synthesis of ≤ 10 nm Magnetite Nanoparticles and Their Application for Removal of Heavy Metals from Water

Abstract

Fe3O4 nanoparticles having size ≤ 10nm were prepared by reverse co-precipitation method. This is a rapid, simple, and cost-effective (only one Fe-salt is used) synthesis route in only one step reaction without applying temperature, surfactants or inert gases as compared with previously published routes. The prepared nano particles were investigated by X-ray (XRD), transmission electron microscope (TEM), thermal gravimetric analysis (TGA), fourier transform infrared (FT-IR) and vibrating sample magnetometer (VSM). These nanoparticles were appraised as an adsorbents for eliminating Pb(II), Cu(II), and Zn(II) from water. The equilibrium data was analyzed by Langmuir, Freundlich, and (D-R) isotherms. Pseudo-second-order, Elovich and intra-particle diffusion models were used to study the kinetics of reaction. Adsorbent cycling was performed to examine its stability and reusability. The results revealed that the adsorption efficiency trend was Pb>Cu>Zn at pH 5.5, 6.5 and 6, respectively and influenced by ionic radius of cations. The maximum suitable mass of adsorbent was 200mg, after which the agglomeration occurred and adsorption efficiency decreased. It is indicated that the adsorption process was well fitted to Langmuir. Also, the adsorption followed the pseudo-second-order-model for Pb(II) and Zn(II), but Elovich for Cu(II). Adsorbent retained about 90% with Pb(II), 40% with Cu(II), and 30% with Zn(II) of its initial sorption efficiency after 3 cycles.