Transition metal ions have been extensively studied for the removal of heavy metal ions as efficient adsorbent from aqueous solution. In this work, Fe2O3 nanoparticles were synthesized by thermal decomposition route of FeSO4.4H2O at the presence of urea (1:1 molar ratio) at two different temperatures (500 °C and 600 °C) and characterized by XRD and TEM. The XRD result show that single-phase of α-Fe2O3 was prepared by increasing of calcination temperature from 500 °C to 600 °C. TEM images confirmed that the as-prepared products have a different shapes and that particle sizes are in the range of tens nanometers. The average crystallite size of pure α-Fe2O3 calculated from XRD pattern was 53.1 nm and 41 nm, respectively, depending on the method employed. In addition, Pb(II) adsorption has been studied and considered as a function of pH solution, contact time, initial Pb(II) concentration and also adsorbent dosage. The adsorption results show that the iron oxides were able to high percentage remove Pb(II) by increasing of contact time, adsorbent dosage and initial Pb(II) ion. The pH solution of 6 proved to be the most suitable for the removal of Pb(II). تفاصيل المقالة

Cr2O3 nanoparticles were synthesized via solid-state thermal decomposition of the mixture of Cr(NO3)3∙9H2O (as Cr precursor) and benzoic acid (as fuel) at 500 or 600 ºC for 3 h and characterized by FT IR and UV Vis spectroscopy, VSM, XRD and TEM. Also, characterized using zeta potential PZ measurement. FT IR and XRD results confirm high degree of crystallinity of Cr2O3 nanoparticles with ≈ 16-18 nm average crystallite size. The size distribution of the as prepared Cr2O3 nanoparticles is estimated to be in the range of 10-60 nm using TEM images. The morphology of the as prepared Cr2O3 nanoparticles is almost ellipsoidal or pseudo spherical. In addition, the photocatalytic degradation of methyl orange (MO) under UV light was studied. The effects of pH solution, sorbent dose and irradiation time were investigated. Based on changes in the UV-Vis spectra of MO, photocatalytic efficiencies were calculated about 91% and 89% for CeO2 nanoparticles prepared at 500 or 600 ºC, respectively. تفاصيل المقالة