Starch functionalization of iron oxide by-product from steel industry as a sustainable low cost nanocomposite for removal of divalent toxic metal ions from water.

Heavy metal removal by waste material from different industry has become one of the main economical approaches for zero waste industrial activity. Therefore, iron oxide fine waste by-product from steel industry was converted into nanoparticulates (Fe2O3 NPs) and further crosslinked with starch as a good stabilizer and biodegradable polymer using formaldehyde to form Fe2O3 NPs-Starch nanocomposite. The scanning electron microscope (SEM) showed the average particle size (40-70 nm). The sorption behavior of this nanocomposite was investigated using Pb(II), Hg(II) and Cd(II). Different factors such as solution pH, contact time, nanocomposite dosage and metal concentration were monitored to determine the adsorptive capacity. Langmuir, Temkin, Freundlich and Dubinin-Radushkevich models were employed to study the adsorption isotherms. The maximum sorption capacities were 2000 mg g-1 for Pb(II), 133.3 mg g-1 for Hg(II) and 322.58 mg g-1 for Cd(II). The results referred that Hg(II) and Cd(II) were best fitted by all models except Pb(II) obeyed the Freundlich isotherm model only. The Fe2O3 NPs-Starch nanocomposite emphasized its potential application as a sustainable low cost nanocomposite for metals extraction from tap water, marine water and industrial wastewater with percentage recovery 93-97%, 70-94% and 76-93%, respectively.