Research on obtaining gadolinium oxide from waste technologies for processing of uranium-gadolinium containing materials

One of the activities of the Uranium production of JSC “UMP” is the processing of hard-to-open uranium-gadolinium-containing scraps. When processing materials of this type, after their dissolution, the gadolinium fluoride precipitation operation is carried out with the subsequent extraction purification of the obtained uranyl nitrate solutions. At the deposition stage, almost all the gadolinium contained in the scraps is transferred to the GdF3 precipitate and sent to the tailings dump as part of the solid waste. In order to determine the possibility of obtaining gadolinium oxide from waste processing of uran-gadolinium containing materials, exploratory studies were initiated. In the course of the work, various methods of obtaining gadolinium oxide were tested. A number of experiments were carried out to refine the modes of obtaining gadolinium oxide by the method of two-stage precipitation of oxalate. A technological scheme was developed, according to which a finished product was obtained, suitable for further use in the technology of obtaining uranium-gadolinium tablets of UMP JSC. The scheme consists of the following main operations: dissolution of gadolinium fluoride in a solution of aluminum nitrate, precipitation of gadolinium oxalate, washing of gadolinium oxalate in the first stage of precipitation with a solution of nitric acid, conversion of oxalate to gadolinium hydroxide, dissolution of hydroxide in a solution of nitric acid, re-precipitation of gadolinium oxalate, calcination to gadolinium oxide.

Ceramic Processing of Silicon Carbide Membranes with the Aid of Aluminum Nitrate Nonahydrate: Preparation, Characterization, and Performance

The development of a low-cost and environmentally-friendly procedure for the fabrication of silicon carbide (SiC) membranes while achieving good membrane performance is an important goal, but still a big challenge. To address this challenge, herein, a colloidal coating suspension of sub-micron SiC powders was prepared in aqueous media by employing aluminum nitrate nonahydrate as a sintering additive and was used for the deposition of a novel SiC membrane layer onto a SiC tubular support by dip-coating. The sintering temperature influence on the structural morphology was studied. Adding aluminum nitrate nonahydrate reduced the sintering temperature of the as-prepared membrane compared to conventional SiC membrane synthesis. Surface morphology, pore size distribution, crystalline structure, and chemical and mechanical stability of the membrane were characterized. The membrane showed excellent corrosion resistance in acidic and basic medium for 30 days with no significant changes in membrane properties. The pure water permeance of the membrane was measured as 2252 L h−1 m−2 bar−1. Lastly, the final membrane with 0.35 µm mean pore size showed high removal of oil droplets (99.7%) in emulsified oil-in-water with outstanding permeability. Hence, the new SiC membrane is promising for several industrial applications in the field of wastewater treatment.

Synthesis and Research of Alumina Ceramics Properties

The article describes in detail alumina powder synthesis by different methods at varying parameters. The technique of obtaining ceramics and the research of the optical properties for determining the materials with the maximum luminescence efficiency is presented. The concentration of the luminescence intrinsic centers and various defects differ for ceramics synthesized by different methods. It is determined that ceramics based on the powder synthesized by a sol-gel method has the maximum thermoluminescence intensity in the F-center peak, whereas for the peak of 360 °C it is obtained with the powder prepared by precipitation of aluminum nitrate with a PEG‑20000 stabilizer.

Ecotoxicological Evaluation of Ethylammonium Nitrate and Aluminium Salt Mixture

The ecotoxicity of a mixture of the ionic liquid ethylammonium nitrate (EAN) and aluminum nitrate salt (Al(NO3)3), as well as the corresponding pure components, was studied in this work. This mixture is of singular interest as electrolytes in electrochemical applications and data on the effects of mixture and components on the environment can hardly be found in the literature. Changes in the bioluminescence of the Aliivibrio fischeri (Beijerinck) Urbanczyk bacteria, determined through a Microtox® test, and microbial activity, measured by microcalorimetry, of two soils with different organic matter contents when exposed to solutions of different concentrations of these compounds were analyzed.

Synthesis of ZSM-23 Zeolite by Two-Stage Temperature-Varied Crystallization and Its Isomerization Performance

Several ZSM-23 zeolites with different acid distributions are synthesized by two-stage temperature-varied crystallization and changing the species of aluminum source via conventional hydrothermal synthesis. The crystallinity, micropores, external specific surface area and the Si/Al ratios are measured by XRD, BET, ICP and XPS, indicating that both the body phase and the surface of the zeolite synthesized by two-stage temperature-varied crystallization have higher Si/Al ratio, and the zeolite synthesized with aluminum nitrate as the aluminum source exhibit the largest specific surface area. The properties of acidity and Pt obtained by NH3-TPD, TEM, Py-IR and H2-TPR show that the suitable B-acid distribution leads to high Pt dispersion over the zeolite. Applying these catalysts to the isomerization of n-dodecane, the zeolite synthesized with aluminum sulfate as aluminum source by two-step temperature-varied crystallization shows the best isomerization performance, that the selectivity of i-dodecane reaches 81.2% at 90.7% conversion. Therefore, the matching of acidity, external specific surface area and Pt dispersion of the zeolites is the key to improve the isomerization performance of long-chain alkanes.

In Situ Synthesis of Alumina Nanoparticles in a Binary Carbonate Salt Eutectic for Enhancing Heat Capacity

A binary carbonate salt eutectic (Li2CO3-K2CO3)-based nanofluid was in situ synthesized by mixing with a precursor material, aluminum nitrate nonahydrate (Al(NO3)3·9H2O). Thermal decomposition of the precursor was successfully carried out to synthesize alumina (Al2O3) nanoparticles at 1 wt.% concentration. A thermogravimetric analysis (TGA) confirmed a complete thermal decomposition of aluminum nitrate nonahydrate to alumina nanoparticles. A transmission electron microscope (TEM) was employed to confirm the size and shape of the in situ formed nanoparticles; the result showed that they are spherical in shape and the average size was 28.7 nm with a standard deviation of 11.7 nm. Electron dispersive X-ray spectroscopy (EDS) confirmed the observed nanoparticles are alumina nanoparticles. A scanning electron microscope (SEM) was employed to study microstructural changes in the salt. A differential scanning calorimeter (DSC) was employed to study the heat capacity of the in situ synthesized nanofluid. The result showed that the heat capacity was enhanced by 21% at 550 °C in comparison with pure carbonate salt eutectic. About 10–11 °C decrease of the onset melting point of the binary carbonate salt eutectic was observed for the in situ synthesized nanofluids.