以表面改質天然多醣體合成氧化鋅之研究;Surface modification of natural polysaccharides synthesis of zinc oxide

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题名:	以表面改質天然多醣體合成氧化鋅之研究;Surface modification of natural polysaccharides synthesis of zinc oxide
作者:	江庭妍;Jiang,Ting-Yam
贡献者:	環境工程研究所
关键词:	氧化鋅;羧甲基;交聯;纖維素;澱粉;carboxymethyl;zine oxide;cross-linking;cellulose;starch
日期:	2012-07-17
上传时间:	2012-09-11 18:17:44 (UTC+8)
出版者:	國立中央大學
摘要:	傳統廢水處理方法有化學沉降法、高級氧化程序、生物處理及吸附等，而這些方法皆需要添加藥劑或吸附劑，增加處理成本，因此，近年來興起利用光觸媒技術去除廢水污染物。本研究利用具有低成本與低污染特性之天然多醣體，進行改質，使其與金屬鋅錯合，再進一步熱解鍛燒合成氧化鋅。本研究選用澱粉及纖維素為基質進行改質，於澱粉方面，探討其交聯羧甲基澱粉及羧甲基澱粉其吸附鋅能力之差異，並了解其交聯程度對鋅吸附能力的影響；由實驗結果得知交聯確實可以提升對鋅之吸附能力，然而卻隨著交聯程度增加，羧甲基置換度有下降的趨勢。纖維素部分，則分別探討醚化溫度、改質溶劑和氯乙酸濃度對羧甲基置換度之影響，研究結果發現最佳改質條件為醚化溫度60℃、以乙醇作為改質溶劑，及氯乙酸濃度為0.65M，對金屬鋅有最大之吸附量。由於考量染整業廢水具有高色度之問題，難以達到放流水標準，故本研究選定染劑剛果紅及甲烯藍作為光催化污染物，將天然多醣體製備之氧化鋅進行對污染物之光催化實驗，並比較不同天然多醣體所製備之氧化鋅其降解效率。由研究成果可以得知，由交聯劑1%之交聯羧甲基澱粉所製備氧化鋅具有較佳之降解效率，是因為比表面積較大。The traditional wastewater treatment methods such as chemical settling method, advanced oxidation processes, and biological treatment required to use agents or adsorbents, which is highly cost effective. Therefore, in recent years, photocatalyst technology is used for the removal of the wastewater pollutants. In this study, we have chosen the natural polysaccharide (starch and cellulose) due to their low-cost, low pollution, their (both unmodified and modified) enhanced affinity for zinc metal to synthesize zinc oxide (ZnO) on further pyrolysis (calcination). In the aspect of starch, The results indicated that cross-linking can indeed enhance the adsorption capacity for zinc. However, with the increase in the degree of crosslinking, the degree of carboxymethyl is descending. In the case of cellulose, the effects of temperature of the etherification, solvent and chloroacetic acid concentration were investigated respectively. The results showed that the optimal etherification temperature as 60 °C, ethanol as a modified solvent, and chloroacetic acid concentration as 0.65 M.Considering the dyeing industry wastewater with high chroma, it is difficult to achieve the effluent standards. So we selected dye Congo red and methylene blue as the photocatalytic pollutants and the zinc oxide prepared from natural polysaccharide as photocatalyst in photocatalytic experiments. Results showed that zinc oxide that prepared by the carboxymethyl starch with 1% cross-linking agent, has higher degradation efficiency because of the larger specific surface area.
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