表面改質之多孔洞吸附介質對特定污染物吸附之研究;Formation of functionalized mesoporous silicas and factors affecting adsorption of heavy metal from aqueous solution

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題名:	表面改質之多孔洞吸附介質對特定污染物吸附之研究;Formation of functionalized mesoporous silicas and factors affecting adsorption of heavy metal from aqueous solution
作者:	林玲珠;Lin,Ling-Chu
貢獻者:	環境工程研究所
關鍵詞:	吸附;多孔性吸附介質;影響因子;改質;聚合作用;表面鑑定;adsorption capacity;control factor;functionalization;mesoporous materials;polymerization;surface characterization
日期:	2013-01-26
上傳時間:	2013-03-25 16:23:24 (UTC+8)
出版者:	國立中央大學
摘要:	一般多孔性吸附介質孔洞常具備大小分佈不均、比表面積不夠高，且對特定金屬無選擇性等缺失。本研究透過不同條件合成多孔洞吸附材料，並藉由改變不同改質影響因子，如水分子效應、溶劑效應、官能基濃度及種類等，以瞭解各項影響因子對官能基於多孔洞材料鍵結率之影響，藉此探討多孔性介質之孔洞大小、比表面積變化、表面結構之差異、官能基之鍵結量多寡與不同改質方法於混合液中對特定金屬 (Hg2+、Ag+) 之選擇性吸附效果，以達到合成對特定重金屬吸附能力良好之吸附介質，解決對環境有害之重金屬污染問題。改質前後之多孔性吸附介質分別以TGA、EA、BET、FTIR、13C NMR、及SEM等儀器進行表面特性鑑定，探討不同影響因子及官能基對吸附介質特性之影響。經BET表面鑑定，改質前C9及C16孔徑分別為2.43nm及3.18nm比表面積為981.65m2/g及1,013.28m2/g。改質前吸附等溫線為第IV型，改質後因孔洞為官能基所阻塞，而轉變為第II型，類似非孔洞材料。由13C NMR及FT-IR可以確認本研究已成功將巰基、氨基及氰基等官能基接枝於多孔洞吸附介質表面，其中以孔洞大小及水份含量影響接枝率最大。EA鑑定結果，官能基覆蓋率亦相當高，平均鍵結率可高達2.0 mmol SH/g，其中又以C9-SAnC (11.37%; 3.55 mmol SH/g) 最高。本研究對Hg2+的吸附量以C16-SHC最高，達126.58 mg/g (0.63mmol/g)。Hg2+/S莫耳比以C16-SHC的0.62為最高，其次為C16-SAnC的0.44。經評估各項影響影響因子，以溶劑之影響最為重要，其次為孔徑大小，C16-SHC吸附介質表面官能基以單層鍵結之型態居多，其飽和吸附量為其他多孔性吸附介質所無法比擬。對Ag+離子所進行之吸附實驗結果，除了C9-LHT吸附量最少為71.94 mg/g (0.67 mmol/g)外，其餘多孔洞吸附介質吸附量均大於1.0 m mol/g，尤其以C16-SHT之吸附量更高達250.00 mg/g (2.32mmol/g)，遠大於目前文獻發表的任何多孔性吸附劑之吸附量。以Freundlich 模式擬合較Langmuir模式更適合用來描述未改質C9及C16之吸附行為，且改質後之多孔洞吸附劑較適合以Langmuir模式來描述吸附Ag+、Hg2+離子之吸附平衡等溫線，而改質後多孔洞吸附劑對Ag+之吸附動力模式則以擬二階擬合最為合適。本研究不論是於何種改質條件下進行改質，改質後多孔洞吸附介質對Hg2+及Ag+離子吸附量均較未改質增加百倍以上。顯示本研究所開發的合成及改質方法能夠成功合成對特定金屬具極高親和力的多孔性吸附介質，而吸附Hg2+或Ag+之改質多孔洞吸附劑後續亦能被應用於抑菌及環境衛生等方面。Mesoporous materials lack for uniform pore-size distribution, ordered pore structure, and high surface area. Meosporous materials are also less selectivity toward heavy metal adsorption. This study described the effective synthesis of mesoporous materials by altering different synthesis parameters. Subsequently, the synthesized mesoporous materials were functionalized under different controlling factors, such as water effect, solvent effect, different functional groups and concentration of functional group to enhance the adsorption capacity toward metal ions such as Hg2+ and Ag+. In the same time, the effects of changing pore size, surface area, and morphology of the mesoporous material were also evaluated in this studied.The before and after functionalized mesoporous materials were characterized by TGA, EA, BET, SEM, FT-IR, and 13C NMR to verify the effect of the controlling factors on the functionalized mesoporous material. The C9 and C16 had surface area of 981.62 m2/g and 1013.28 m2/g; pore size of 2.43nm and 3.18nm, respectively. The BET isotherms curve for the unmodified samples were typical type IV. The BET isotherms curve for functionalized samples, which might be caused by blocking pore channel, had been changed to type II. The characteristic FT-IR, and 13C NMR results showed that the functional group had been grafted to the surface of mesoporous successfully. The most important controlling factors for grafting density were pore size and water effect. The EA results showed that the amount of functional group grafted to the surface of mesoporous material were relatively high. The average density was 2.0 mmol SH/g, and C9-SAnC sample had the highest grafting amount (11.37%, 3.55mmol SH/g). The Freundlich model better described the unmodied samples adsorption behavior. However, the adsorption behaviors of the functionalized samples were better delineated by Langmuir model. The pseudo second order fitted the Ag+ adsorption kinetic model better. The adsorption experiments results showed that the C16-SHC had the highest Hg2+ adsorption capacity of 126.58 mg/g (0.63mmol/g). The C16-SHC had the highest Hg2+/S molar ratio of 0.62. The C16-SAnC came in second of 0.44. The factors influence the adsorption capacity the most were solvent effect, and pore size. The average Ag+ adsorption capacity was 1.0 mmol/g. The C16-SHT had the highest adsorption capacity of 250.00 mg/g (2.32mmol/g). The C9-LHT had the lowest adsorption capacity 71.94 mg/g (0.67 mmol/g). The results were higher than those of other researchers’. The adsorption capacity of functionalized mesoporous materials under all control factors were enhanced by two orders. This study developed the synthesis and functionalization method with high affinity toward adsorbing heavy metal successfully. The functionalized mesoporous material can be reused as bacteria inhibitor after adsorbing Hg2+ and Ag+ ions.
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