Design And Assembly Of Micro/Nanostructure Alumina And Its Uranium Adsorption Behavior

It is well known that the morphology, size, and spatial arrangement of materials have animportant influence on their properties. Recently, the design and fabrication of nanomaterialshave attracted considerable interest because of their widely potential applications.Nanoalumina has unique surface effect, small size effect, quantum size effect andmacroscopic quantum tunneling effect, and that has the properties of high strength, highhardness, heat resistance, corrosion resistance and so on. Therefore, it has been widely appliedin petrochemical industry, ceramics, new materials, microelectronics, aerospace and otherfields because of excellent performance in mechanics, optics, thermology, electricity andchemical reactions. This thesis prepared alumina nanosheets, nanorods by supercritical carbondioxide technology and alumina hollow microspheres via a facile self-template process,what’s more, we researched the adsorption efficiency of uranium on these alumina materialsfrom aqueous solution.Boehmite precursor was synthesized in the presence of supercritical carbon dioxide. Theamorphous product was crimped to various nanosheets through the exfoliation of supercriticalCO₂molecules. γ-Al2O3nanosheets with a high specific surface area were obtained after anannealing process. This paper deals with the attempts for the optimum recovery conditions ofuranium on alumina adsorbent as a function of pH values, contact time, adsorbent dosage,initial uranium concentration and temperature. The result shows that this kind of materialexhibits high efficiency for the removal of uranyl ions.Anion and cation aluminum salts solution were mixed to obtain desired sol, andnatroalunite nanosheets could be prepared by combined sol-gel process and supercriticaltechnology. γ-alumina nanorods with a diameter of15-45nm and a length of60-150nm weresuccessfully obtained after a calcined procedure. Interestingly, numerous of γ-aluminananorods aggregated and formed into nanosheets, which was related to the morphology ofprecursor natroalunite. The probable formation mechanism was described as layer-by-layerself-assembly, and Ostwald ripening, and the reassembly of atoms, with the assistance of timedependent experiments.A simple solvothermal method was used to synthesize alumina hollow microspheresthrough a self-template process. Organic compounds core could be removed through a heat treatment to precursor microspheres with a core-shell structure. Alumina hollow microspheresas-prepared has a high specific surface area of326.4m²/g, which was proved to have a highadsorption capacity of19.51mg/g for the removal of uranium.