Removal of Cobalt-60 Radionuclides from Aqueous Solution Using Novel surface-modified Hematite Nanoparticles

Throughout the years, humans have entered the environment with potentially hazardous wastes such as heavy metals and radioactive substances, so that it has a direct impact on human health and existing ecosystems. Hence, the investigation on the necessary strategies to control and eliminate these hazards has been the goal of various researches. In this study, the elimination of cobalt 60 radionuclides was investigated due to their abundance in the wastewaters of nuclear industries such as spent fuel reprocessing plants and nuclear power plants. Thus, novel surface-modified hematite nanoparticles (α-Fe2O3 NPs) were prepared by hydrothermal method at 250 °C and using iron(III) chloride hexahydrate (FeCl3.6H2O) and oleic acid (C₁₈H₃₄O₂) as raw materials for the removal of cobalt-60 radiostations from aqueous solutions. The synthesized α-Fe2O3 NPs were characterized by XRD, FT-IR, SEM, TEM, and BET. According to the results, the synthesized nanocrystals were more (90%) of nanorods 60-30 nm, along with irregular hexagonal nanoscale particles at a thickness of 40- 100 nm distributed among them.  The specific surface area was determined 31.29 m2/g and the effect of some variables such as pH, adsorbent weight, initial concentration of cobalt-60 radio cations, temperature, and contact time was significant on the absorption process. The optimized condition for cobalt-60 removal from aqueous solution was obtained in 25±1 °C , initial radio cation concentration of 1 mg/L, pH 6.5, contact time of 2 h, and nano α-Fe2O3 sorbent concentration of 20 mg/L. On the other hand, the Redlich-Peterson isotherm model was suitable for describing homogenous cobalt-60 adsorption with the maximum uptake capacity 142.86 mg/g at 25±1 °C. In contrast, analysis of experimental data showed that the cobalt-60 adsorption onto the synthesized nano α-Fe2O3 well fitted the Ho model as linear pseudo-second-order kinetics. Therefore, it can be concluded that the synthesized novel surface-modified α-Fe2O3 NPs is an effective, promising, and environment-friendly adsorbent with high capability in the removal of cobalt-60 radionuclides from aqueous solutions such as wastewaters.