Baseline evaluation for natural radioactivity level and radiological hazardous parameters associated with processing of high grade monazite.

Egyptian monazite is a promising resource and investment attractive for production of valuable metals of industrial or nuclear interest such as rare earth elements (REEs), thorium (Th) and uranium (U). The study was focused to establish a baseline framework in viewpoint of radiation protection for the workers in production of REEs from high-grade monazite treated by sodium hydroxide (NaOH) solutions. Radiological hazard indices (cancer, gonadal and other risks) were evaluated, due to emissions (α-, ß- and γ-radiations) of radium-isotopes (228Ra, 226Ra, 223Ra) and lead (210Pb). The values of the estimated radiological hazard indices were higher than the permissible safe limits, worldwide average and varied with those reported in other countries. It was found that more than 70% of radioactivity and radiological hazardous indices resulted from emissions of 228Ra, while the rest was attributed to 226Ra, 223Ra and 210Pb. Therefore, processing of the Egyptian monazite can cause a significant radiological impact on workers through external exposure from γ-radiations and/or internal exposure through inhalation or ingestion airborne contaminated by the radionuclides. Thus, the results recommended that protection rules could be considered to prevent the radiation hazards associated with the production of the REEs from the high grade monazite attacked by caustic method.

Uranyl ions adsorption by novel metal hydroxides loaded Amberlite IR120.

In this work, Ni(OH)2-loaded Amberlite IR120 (Ni-MA) and Co(OH)2-loaded Amberlite IR120 (Co-MA) resins were prepared, characterized and applied for UO2(2+) removal from aqueous solutions. The adsorption characteristics were investigated in a batch system with respect to effect of contact time, pH, equilibrium isotherms and removal kinetics data. The results indicated that the UO2(2+) could be efficiently removed from aqueous solutions at pH = 3.5 using Ni-MA and Co-MA resins. The maximum adsorption capacities for the UO2(2+) of Ni-MA and Co-MA were found to be 439 mg/g and 451 mg/g respectively. The equilibrium data fit well with the Langmuir adsorption isotherm. Kinetics study showed that the adsorption process was fast and reached equilibrium within 60 min and the kinetics data fit well with pseudo-second order and intra-particle diffusion models for both resins. The adsorption mechanism has been proposed and discussed. It was found that both Ni-MA and Co-MA resins could be used effectively for UO2(2+) removal from aqueous solutions.