| Summary: | 碩士 === 東海大學 === 環境科學系 === 91 === This study thermally treated Cu- or Cr-sorbed rice husk at 300, 500, 700, or 900˚C for 2 hrs. The Cu- or Cr-concentrating level, carbon content, morphology, and metal species were studied by using Flame Atomic Absorbance Spectrophotometer (FAAS), Elementar Analyzer (EA), Scanning Electron Microscope (SEM), X-ray Diffractometer (XRD), and X-ray Absorption Spectroscopy (XAS).
The results showed that the Cu- or Cr-concentrating level was higher in the top layers than that in the bottom ones after thermal treatment at 300, 500, 700, or 900˚C for 2 hrs. The SEM observation indicated that the morphology of Cu- or Cr-sorbed rice husk did not changed obviously after thermal treatment at 300―700˚C for 2 hrs. At 900˚C, the surface of Cu-sorbed rice husk became smoothing, we suggested there was sintering phenomenon happened during heating at 900˚C.
The XRD results showed that the phase of SiO2 transformed from amorphous to crystobalite during thermal treatment at 500―700˚C for 2 hrs. At 900˚C, we found that parts of SiO2 transformed into the phase of Tridymite-M. The XAS results showed that the major Cu species in the top layers of Cu-sorbed rice husk heated at 300―500˚C was CuO (92%) while that in the bottom ones were CuO (27―46%) and Cu2O (18―44%). At 700―900˚C, we found the formation of Cu9Si10O29．11H2O. The major Cr species of Cr-sorbed rice husk was Cr2O3 (62%, at 300˚C), with the increasing temperature, the portion of Cr2O3 increased, too (95%, at 900˚C).
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