本研究主題是利用共沉澱法及溶膠凝膠法合成奈米氧化鐵礦物系列（奈米赤鐵礦、奈米鈦鐵礦、奈米磁鐵礦、奈米針鐵礦、奈米磁赤鐵礦），藉由調變不同的合成參數去合成出三種不同粒徑的奈米氧化鐵礦物，並比較不同粒徑對銅離子吸附的影響及探討其光催化降解污染物之效益。從XRD圖譜中可知：我們成功地合成出不同粒徑的奈米氧化鐵礦物，但奈米鈦鐵礦卻含有Fe2TiO5的雜相；由TEM影像上，我們可以觀察到不同粒徑奈米氧化鐵的表面形貌及粒子分布情況；BET結果顯示：隨粒徑變小，奈米氧化鐵礦物其比表面積變大；從SQUID分析可以得知，粒徑大小將影響到其矯頑磁場及殘留磁化量/飽和磁化量比例。從UV-Vis量測可知︰奈米氧化鐵礦物都屬於可見光能隙範疇。在銅離子吸附結果中可知：溶液pH值越高，越有利於吸附，且比表面積值也會影響到其最大吸附量；銅離子吸附為假二階吸附模式且符合Langmuir之等溫吸附模式。紫外光光催化結果顯示：高比表面積值及對紫外光有高吸收度會有比較好的光催化效率；可見光光催化結果顯示：高比表面積值及對可見光有高吸收度亦會有比較好的光催化效率。綜合以上結果可顯示：我們所製備的奈米氧化鐵礦物系列兼具光催化與銅離子吸附之功能，故可應用於環境汙染處理上。

關鍵詞：磁鐵礦、磁赤鐵礦、赤鐵礦、鈦鐵礦、針鐵礦、吸附、光催化

In this study, the iron oxide nano-minerials ( magnetite、maghemite、hematite、ilmenite and goethite）are synthesized using a sol-gel and co-precipitation method. We want to synthesize different particle sizes of iron oxide nano-minerials to investigate the effect of particle size on the photocatalytic activity and heavy metal adsorption.
From the XRD pattern, it is observed that we can successfully synthesize different particle sizes of nano-minerals, and they have a pure crystalline phase except nano-ilmenite. TEM images also show the particle sizes of all the nano-minerals are in the nano-scale, and they are a little aggregated except nano-hematite. The BET results exhibit a higher specific surface area with a smaller particle size of nano-minerals. The SQUID result shows the coercivity field, and the ratio of remnants of magnetic moment and saturated magnetic moment would be affected by the particle size. It is also found that the band gap of nano-minerals belongs to the range of visible light.
It is observed that the Cu2+ adsorption seems favorable for a higher pH condition, and the surface area is the key factor to influence the adsorption activity. Furthermore, the Cu2+ adsorption behavior of all the nano-minerals are well fitted to the pseudo-second order equation and it belongs to Langmuir isotherm. The photocatalytic activity under UV-light irradiation suggests that a higher surface area and higher absorbance of nano-minerals would own a higher photocatalytic efficiency. The photodegradation under Vis-light irradiation is dependent on the factors of surface area and absorbance of vis-light. Therefore, these findings indicate that iron oxide nano-minerials are effective materials for Cu2+ removal and, together with its photocatalytic activity, may be applied in the environmental treatment.

Keywords: magnetite、maghemite、hematite、ilmenite、goethite、adsorption、photocatalysis.

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