Structure and Properties of Some Layered UO Phases: A Density Functional Theory Study.

UO is the boundary composition between the fluorite and the layered structures of the UO system and the least studied oxide in the group. δ-UO is the only layered structure proposed so far experimentally, although evidence of fluorite-based phases has also been reported. Our DFT work explores possible structures of UO stoichiometry by starting from existing MO structures (where M is an actinide or transition metal) and replacing the M ions with uranium ions.

Ab initio investigation of the UO3 polymorphs: structural properties and thermodynamic stability.

Uranium trioxide (UO3) is known to adopt a variety of crystalline and amorphous phases. Here we applied the Perdew-Burke-Ernzerhof functional + U formalism to predict structural, electronic, and elastic properties of five experimentally determined UO3 polymorphs, in addition to their relative stability. The simulations reveal that the methodology is well-suited to describe the different polymorphs.

Density functional theory investigation of the layered uranium oxides U3O8 and U2O5.

Oxidation of UO(2) in the nuclear fuel cycle leads to formation of the layered uranium oxides. Here we present DFT simulations of U(2)O(5) and U(3)O(8) using the PBE + U functional to examine their structural, electronic and mechanical properties. We build on previous simulation studies of Amm2 α-U(3)O(8), P2(1)/m β-U(3)O(8) and P6[combining macron]2m γ-U(3)O(8) by including C222 α-U(3)O(8), Cmcm β-U(3)O(8) and Pnma δ-U(2)O(5).

Banana peel: a green and economical sorbent for the selective removal of Cr(VI) from industrial wastewater.

This study describes the use of banana peel, a commonly produced fruit waste, for the removal of Cr(VI) from industrial wastewater. The parameters pH, contact time, initial metal ion concentration, and temperature were investigated and the conditions resulting in rapid and efficient adsorption (95% within 10 min) were determined. The binding of metal ions was found to be pH dependent with the optimal sorption occurring at pH 2.

Evaluation of sorption of uranium onto metakaolin using X-ray photoelectron and Raman spectroscopies.

Metakaolin prepared from a natural clay mineral ore of aluminium kaolinite is a promising low cost and high activity aluminosilicate material that has been investigated for studying the sorption behavior of uranium. Here, metakaolin was characterized using X-ray photoelectron spectroscopy (XPS) and the effects of pH, contact time and initial metal ion concentration on its sorption behavior were studied. The sorption process was found to initially be rapid (approximately 60% at time 0 min) but became slower with time; equilibrium was established within 24 h (approximately 80% sorption).

Characterization of banana peel by scanning electron microscopy and FT-IR spectroscopy and its use for cadmium removal.

This study describes the use of banana peel, a commonly produced fruit waste, for the removal of Cd(II) from environmental and industrial wastewater. The banana peel was characterized by FT-IR and scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDX) analysis. The parameters pH, contact time, initial metal ion concentration and temperature were investigated and found to be rapid ( approximately 97% within 10 min).

Determination of the elemental composition of mature wheat grain using a modified secondary ion mass spectrometer (SIMS).

An imaging secondary ion mass spectrometry system has been developed that allows the distribution of elements or ions to be superimposed on an image of the plant cell or tissue generated by ion-induced secondary electrons. This system has been evaluated by analysing the aleurone and sub-aleurone cells of mature wheat grain, showing high spatial resolution (100-200 nm) images of O-, PO(2)-, Mg+, Ca+, Na+ and K+ within the phytate granules of the aleurone, with CN- being diagnostic for proteins and C(2)- being diagnostic for starch in the starchy endosperm cells. This system should provide improved localization of elements in a range of other plant systems.