Characteristics of Cu(II) and Zn(II) adsorption on sediments from typical urban polluted rivers in Dianchi Lake

This study was conducted to determine the spatial distribution characteristics of Cu and Zn adsorption on the sediments of the estuary of Dianchi Lake, as well as the adsorption laws of Cu and Zn on combinations of sediment organic matter, metal oxides, and organic-inorganic composites.A static adsorption experiment was applied to four groups of sediments from the estuary of Dianchi Lake, and results were generated through correlation analysis and redundancy analysis. The four groups were as follows: (1) Untreated, Group A, (2) Organic matter removed, Group B, (3) Iron and aluminium oxide removed, Group C, (4) Organic matter and iron and aluminium oxide removed, Group D. The adsorption capacity was correlated with the spatial distribution along the direction of river flow and vertical depth. High contents of various components of the sediment did not correlate with high adsorption capacities for Cu and Zn, according to the use of four groups of sediments subjected to different treatment processes. The adsorption of Cu fit the Freundlich isotherm adsorption model for all four sediment groups. For Zn adsorption, the untreated and removed organic matter and Fe-Al oxide groups were in good agreement with the Freundlich model, while the removed organic matter and removed Fe-Al oxide groups were in good agreement with the Langmuir isothermal adsorption model. The results indicate that there is a quantitative relationship between the adsorption of heavy metals and organic and inorganic complexes in sediments.

Oxidation Behaviors of Aluminum Nanopowders with Different Particle Sizes: A Real-Time Synchrotron X-ray Scattering Study

We have studied the oxidation behaviors of aluminum (Al) nanopowders with different particle sizes using a real-time synchrotron X-ray scattering during annealing in air. The Al nanopowders with small particle size of 78 nm at room temperature (RT) were a single crystal. The surface of the nanopowders was first oxidized to amorphous Al oxide near 450 °C, and then crystallized to γ-Al2O3 phase at 550 °C. The inside of the nanopowders existed as crystal Al phase at 680 °C, high compared to the melting temperature of Al bulk, 660 °C. In contrast, the Al nanopowders with large particle size of 816 nm at RT have multi grains inside a particle. The surface and grain boundary of the powders were first oxidized to amorphous Al oxide near 470 °C, and then crystallized to γ-Al2O3 phase at 550 °C. The inside of the powders existed as amorphous Al phase at 620 °C, melted at 656 °C, and then oxidized gradually above 656 °C.

Effect of Oxygen Concentration in Static Pb-Bi Eutectic on Corrosion Mode of Aluminum-Alloyed Austenitic Steels at 550 °C for 1000 h

Corrosion behavior of Fe-18Ni-12Cr-2.30Al and Fe-18Ni-12Cr-2.90Al-Nb-C austenitic steels was investigated in static Pb-Bi eutectic at 550 °C for 1000 h depending on the concentration of dissolved oxygen in the liquid metal. In the concentration range from 1012 to 108 mass % O, both steels underwent corrosion via dissolution resulted in the formation of spongy ferrite layer depleted in Ni and Cr and penetrated by Pb and Bi. In Pb-Bi with 106 mass % O, Fe-18Ni-12Cr-2.90Al-Nb-C steel oxidizes with formation of very thin (≤ 1 μm) Cr/Al oxide film while Fe-18Ni-12Cr-2.30Al steel shows mixed corrosion behavior represented by more intensive oxidation and dissolution. The features of corrosion response are discussed depending on the composition of steels and concentration of dissolved oxygen in the Pb-Bi eutectic.