Sponge-like Ca-alginate/Lix-84 beads for selective separation of Mo(VI) from some rare earth elements.

In this investigation, a novel alginate complex was developed for the selective separation of molybdenum (Mo(VI)) ions from some rare earth elements (REEs). In this regard, alginate as a natural polysaccharide was impregnated and modified with 2-hydroxy-5-nonylacetophenone oxime (Lix-84) and characterized using FT-IR, TGA/DTA and SEM-EDX. The relation between medium acidity, adsorption kinetics, sorbent dose, isotherm models, temperature and Mo(VI) recovery was investigated. It was concluded that the impregnation stage promoted the Mo(VI) separation. The kinetics and isotherm data were well-fitted and matched with the pseudo-first-order model and Langmuir isotherm model; respectively. The Langmuir maximum adsorption capacity of Mo(VI) reached 72.2 mg/g. The developed material showed excellent separation performance towards Mo ions over the investigated REEs. The desorption and recovery of the loaded Mo(VI) ions were achieved using 1.0 M HCl. Reutilization of Alg/Lix-84 was confirmed up to three adsorption-desorption cycles with no damage of the beads as proved with SEM analysis. The adsorption mechanism of molybdenum onto Alg/Lix-84 was elucidated through FTIR and XPS measurements and was found to be governed by both electrostatic interaction and ion exchange. Therefore, the developed material has a promising potential for the selective separation of molybdenum from REEs-containing solution.

Novel nano network trigonal prismatic Ba2CoO4-deficient BaCoO3 for high-affinity sorption of radiolanthanide elements of biomedical applications: synthesis and sorption studies.

Nano trigonal prismatic Ba2CoO4 with hierarchical structure and deficient BaCoO3 with columnar structure have been prepared at low temperatures (400 [BC4] and 500 [BC5]) °C/3h using green method. X-ray diffraction (XRD) results demonstrate the presence of enriched Ba2CoO4 phase at 400 °C and multiphase structures: BaCoO3, BaCoO3-δ, and Co3O4 with a decrease in the amount of Ba2CoO4 at 500 °C. The prepared powders are characterized by a high specific surface area (SSA) values which are reflected to the mode of synthesis that leads to produce materials with massive active sites. The SSA of BC4 is higher than that of BC5 which can be correlated to the difference in the microstructure analysis of BC4 and BC5 as given from scanning electron microscope (SEM) and high-resolution transmission electron microscope (HRTEM) studies. Electron spin resonance (ESR) spectroscopy as an effective method for the characterization of vacancy-rich nanostructures indicates that the presence of oxygen vacancies is related mainly to BaCoO3, BaCoO3-δ, and Co3O4 phases while the effective oxygen vacancies is in BaCoO3 and BaCoO3-δ. The nanocrystalline structures of BC4 and BC5 as novel nano-adsorbents are the first time to be tested. Production of Gd radioisotopes through natGd(n,γ)153,159,161Gd and carrier-free 161Tb through 160Gd(n,γ,) 161Gd [Formula: see text] 161Tb are achieved at 2nd Egyptian nuclear research reactor (ETRR-2). Preliminary sorption study of Gd radioisotopes (represent the lanthanide elements) shows a promising material for the application in the separation and removal of lanthanide elements. The results demonstrated that the fast interaction and efficient sorption of lanthanides ions are based on the novel synthesized nanomaterial that can be considered for the upscale application in this field.

Kinetics and mechanism of radium-isotopes dissolution in TENORM scale waste associated with petroleum production using certain organic carbon source: lactic acid solution-case study.

The present study is conducted to explore the dissolution as inferred from the kinetic mechanism for radium-isotopes (228Ra, 226Ra, and 224Ra) in the TENORM scale waste deposited in oilfield pipes and equipment, Gulf of Suez, Egypt. The main efficiency factors for Ra2+-compound dissolution by lactic acid (LA) solution, e.g., reactive organic carbon (i.e., electron-donor source), have been investigated, and optimum chemical conditions have been determined. The obtained data were also employed to predict the leaching kinetics and mechanism of the Ra2+-isotopes removal by three shrinking core models (SCM, liquid film process-chemical controlled process-diffusion controlled process) and Arrhenius model. The maximum leaching percentage of Ra2+-isotopes reached to 55-60% at the optimal leaching conditions (0.3 M LA, 5 h, 25 °C, ϕ < 1 mm, S/L ratio 10/50 g mL-1). The Ra-isotopes removal proceeds kinetically by diffusion-controlled process. Activation energy (Ea) of the leaching process was 10.51 kJ mol-1. This value conforms that the leaching process for removal of Ra2+-isotopes in the TENORM scale waste by LA solution is controlled by a diffusion process. Values of thermodynamic parameters (∆Go, ∆Ho, ∆So) were determined and indicate that dissolution of Ra2+-isotopes in the studied waste is non-spontaneous and temperature dependent. Moreover, the leaching mechanism may be attributed to the dissolution of soluble exchangeable and acidic species of Ra2+-species and/or these due conversions of insoluble Ra-sulfate to more soluble Ra-sulfide and/or Ra-hydrogen sulfide by LA solutions.