Young Dong Noh

Mercury(II) exchange by highly charged swelling micas, sodium Engelhard titanosilicate-4, and sodium titanosilicate.

Selective Hg(2+)-exchange properties of highly charged sodium swelling micas (Na-2-, Na-3-, and Na-4-micas), sodium Engelhard titanosilicate-4 (Na-ETS-4), and sodium titanosilicate were determined by use of distribution coefficients (K(d)), ion-exchange isotherms, and Kielland plots for their potential use of Hg decontamination from groundwater and soils. X-ray diffraction (XRD) patterns after 2Na(+) → Hg(2+) exchange were collected to check for change in (001) spacings of differently charged sodium micas. The isotherms and Kielland plots suggested that Na-ETS-4 was highly selective for Hg(2+). Also, the K(d) value of Na-ETS-4 was the highest among the tested exchangers, supporting its high selectivity. Hg releases from Hg-exchanged Na-4-mica and Na-ETS-4 were found to be lower compared to other samples tested with simulated groundwater. The (001) spacings of sodium micas after Hg(2+) exchange changed from ∼ 12 to ∼ 14 Å or/and 12 Å depending on their layer charge density and the uptake amount of Hg. Our results suggest that Na-ETS-4 is a good candidate for mercury(II) decontamination from groundwater and soils.

LiMn2O4-based materials as anodes for lithium-ion battery

LiMn2O4-based materials such as LiMn2O4 and LiMn1.53Ni0.47O3.67 were synthesized by both conventional-hydrothermal (CH), microwave-hydrothermal (MH) methods and calcination route. Both reaction temperature and reaction time during MH routes were lower than those of CH routes. LiMn2O4 electrode materials were assembled into lithium-ion battery anodes and their electrochemical performances were studied. The results proved that these LiMn2O4 electrodes can be served as conversion anode materials, and show electrochemical activity during the potential range of 0.01–3.0 V versus Li+/Li. For LiMn1.53Ni0.47O3.67 materials when used as lithium-ion battery anodes, we found that the introduction of Ni can change their electrochemical reaction and thus improve their electrochemical performances.

Solvothermal/Hydrothermal Synthesis of Metal Oxides and Metal Powders with and without Microwaves

Anatase and Ca, Sr and Ca0.5Sr0.5 hydroxyapatites were synthesized by conventional-hydrothermal (C-H) as well asmicrowave-hydrothermal (M-H)methods.Microwave-assisted reactions led to accelerated syntheses of anatase but no such acceleration of reactions could be detected with the syntheses of hydroxyapatites because the crystallization of the latter materials occurred at very low temperature. Cu and Au metal powders were produced by using glucose, fructose or sucrose as reducing agents under C-H conditions at 160 ℃, where fructose and sucrose were found to be stronger reducing agents than glucose. The crystallinity of all the powders was characterized by powder X-ray diffraction, and morphology and particle sizes were determined by scanning or transmission electron microscopy Graphical Abstract Solvothermal/ Hydrothermal Synthesis of Metal Oxides and Metal Powders with and without Microwaves

Selective Cobalt (II) Exchange Properties of Na-2-Mica and Na-ETS-4

Co2+ exchange isotherms and Kielland plots were determined for highly-charged sodium swelling mica (Na-2-mica) and sodium Engelhard Titano-Silicate-4 (Na-ETS-4). The results showed that both Na-2-mica and Na-ETS-4 were highly selective for Co2+ at (equivalent fraction) of < 0.3. X-ray diffraction (XRD) patterns after 2Na+ → Co2+ exchange process were examined to check for change in d001-spacing of Na-2-mica. As the uptake of Co ions increased, strong ∼14 Å phase (two-layer hydrate) of Na-2-mica increased, while the ∼12 Å phase (one-layer hydrate) decreased. These synthetic ion exchangers have a great potential for decontamination of radioactive or stable cobalt from waste water and soils.