| Abstract: | 本研究自行配置含銅或鉻之稻殼，探討經300?900℃熱處理後，含銅或鉻之稻殼其上、下層殘渣之重金屬濃縮效果，固相物以EA、SEM、XRD、XAS探討經熱處理後，含銅或鉻之稻殼上層及下層之含碳量、表面型態及物種變化 研究結果顯示：不論含銅或鉻之稻殼，經300?900℃熱處理後，上層殘渣之重金屬含量皆較下層為高，顯示經熱處理後，上層重金屬之濃縮程度較下層為佳，但其形成原因仍待探討。由SEM表面觀察結果發現樣品在300?700℃熱處理2小時後，其表面型態並無明顯之改變，於900℃時發現RH表面結構逐漸呈現平滑狀，推測有燒結或融熔現象產生。 XRD結果發現SiO2之晶體在500?700℃過程中，晶相由amorphous轉變為crystobalite；900℃時，peak count逐漸減少，並發現部份SiO2之晶相逐漸轉變為以SiO2, Tridymite-M之型式存在。由XAS結果得知，含銅稻殼在300?500℃熱處理後之上層殘渣中，銅之物種以CuO (92%)為主，下層之銅物種則較為複雜，以CuO (27?46%)及Cu2O (18?44%)為主；當溫度為700?900℃時，發現有Cu9Si10O29．11H2O生成；含鉻稻殼方面，300℃處理後之上層的鉻物種以Cr2O3 (62%)為主，下層則是以Cr(OH)3 (70%)為主，隨熱處理溫度上升，Cr2O3之比例亦隨之增加至95% (在900℃熱處理後)。
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). |
