Uniform orange-like Fe 3 O 4 /polypyrrole (PPy) composite microspheres have been synthesized using Fe 3 O 4 microspheres as a chemical template under sonication. In the orange-like Fe 3 O 4 /PPy composite microspheres, the Fe 3 O 4 particles played the role of ''seeds'' while the PPy was the ''pulp and peel''. A growth mechanism for the orange-like Fe 3 O 4 /PPy composite microspheres was proposed in which partial pyrrole monomers are immersed into the gaps of Fe 3 O 4 microspheres under sonication, meanwhile Fe 3+ ions released from Fe 3 O 4 microspheres in an acidic environment initiated the polymerization of pyrrole monomers in the interior or around the Fe 3 O 4 microspheres, finally forming an orange-like structure. When used as an absorbent of Cr(VI) ions, the as-obtained Fe 3 O 4 /PPy microspheres showed strong adsorption capability with an adsorption capacity of about 209.2 mg g À1 , which is mainly attributed to the PPy ''pulp and peel''. Furthermore, the magnetic Fe 3 O 4 ''seeds'' in composite microspheres make them easy to separate from wastewater by magnetic separation. Recently, polymers, including polyaniline, polyacrylonitrile, poly(p-phenylenediamine), polypyrrole, and sulfophenylenediamine copolymer, were found to be highly efficient absorbents due to their rich functional groups such as -C]O, -CN, -OH, -COO À , etc. [18][19][20][21][22][23][24][25] These polymers exhibited good adsorption performance for heavy metal ions such as Cr(VI) ions. However, it is difficult to synthesize magnetic-based polymer composite materials, since polymers such as polypyrrole or polyaniline are hydrophobic but the surfaces of magnetic particles are

High saturation magnetization monodisperse Fe(3)O(4) hollow microspheres (109.48 emu/g) with superparamagnetic property at room temperature are promptly synthesized by a one-step solvothermal process with the presence of sodium dodecylbenzenesulfonate as an additive. The as-synthesized products possess superparamagnetism, large cavity, high water solubility, and saturation magnetization at room temperature. In particular, these hollow microspheres exhibit both of a rather short separation time from industry wastewater and a high adsorption capacity about 180 mg/g at high Cr(VI) concentrations, which is much better than those of reported magnetite solid nanoparticles. In addition, the X-ray photoelectron spectra (XPS) show that the uptake of Cr(VI) into the spheres was mainly governed by a physicochemical process. The micelle-assisted Ostwald ripening process was proposed to explain the rapid formation of hollow structures by a series of control experiments. The as-manufactured products with the two advantages mentioned above serve as ideal candidates for environmental remediation materials.

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Abstract:The isotopic composition of solid and liquid portions of natural melting snowpack is investigated in detail by the separating of liquid water from snow grains at different depths of the snowpack. The slope of the υD-υ 18 O line for the liquid phase is found to be lower than for the solid phase. This is proved to be due to the isotopic fractionation occurring in the melt-freeze mass exchange within the snowpack. Melting of the snowpack has no clear impact on the υD-υ 18 O line for the solid phase, but the slope of the υD-υ 18 O line for the liquid shows an overall slight decrease in the melting period. When the snowpack is refrozen, the refreezing process would inevitably cause the slope of the solid phase to decrease because of the discrepancy between the slopes of the two phases. Thus the slope of the solid would become lower and lower as the diurnal melt-freeze episodes cycle throughout the melting season. This effect is then demonstrated by looking into the isotopic composition changes of glacier firn. The extent of the effect depends on the snowpack properties and environmental conditions. The slope changes also result in a decreasing trend in deuterium excess.