以回應曲面法探討添加陽離子界面活性劑透過溶膠-凝膠法製備矽膠之影響

Study the Effect of Adding the Cationic Surfactant into the Sol-Gel Process of Making Silica Gels by the Response Surface Methodology

陳鴻博(Hong-bo Chen)

指導教授 ： 鍾財王

中原大學/工學院/化學工程學系/碩士(2007年)

https://doi.org/10.6840/cycu200700538

摘要

吸附劑為吸附式製冷系統中的關鍵要件之一，具有良好吸附性能的吸附劑可使系統達到高效率與高製冷量。本研究利用陽離子界面活性劑CTAB擁有棍狀微胞的特性，其微胞大小介於20 Å～40 Å，利用此特性透過溶膠-凝膠法來製備出高表面積的矽膠，同時也盡量使其孔徑小且分佈均一。

研究中利用TGA與FTIR探討高溫鍛燒將界面活性劑CTAB去除的溫度，由研究結果顯示在經550℃鍛燒5~6小時後確認可將CTAB完全去除，且鍛燒550℃為合理的溫度；並使用統計法中的回應曲面法，來瞭解其製備參數（TEOS濃度、CTAB濃度、pH值）對目標函數（表面積與平均孔徑）的影響情形，研究結果顯示此三項因子對表面積大小有顯著影響，而pH值對孔徑大小有較明顯的效應，此外，TEOS濃度與pH值和CTAB濃度與pH值之間對表面積具有顯著的交互影響，孔徑大小方面並沒有顯著的交互影響；研究中所使用回應曲面模型來描述表面積與平均孔徑之模式，由變異數分析與檢定係數之結果得知，回應曲面模型非常適切地表示實驗數據的變化情形。針對表面積之目標函數，進行最佳化探討，結果顯示以TEOS=0.027、CTAB=0.00835、pH=1的條件，可製備出表面積高達1428m2/g的矽膠。最後針對最佳化條件所製備出之矽膠，進行水氣之平衡吸附量的量測也在本研究中進行。

關鍵字

溶膠-凝膠法 ； 回應曲面法 ； 界面活性劑 ； 吸附量 ； 矽膠

並列摘要

The adsorbent is one of the key components in the adsorption-cooling system. A good adsorbent, which can make the system reach the high efficiency and high refrigeration capacity. The Cationic Surfactant of CTAB have the rod-shape micelles and the size of micelles is between 20 Å～40 Å. Using the CTAB to make the silica gels through the Sol-Gel process, the pore size is and the pore distribution are small.
In this study, we use TGA and FT-IR to observe the calcine temperature of removing surfactant of CTAB. From the results, the CTAB was removed complete at 550℃ calcined temperature and calcined 5~6 hours. Use the Response Surface Methodology to understand the influence between factors (TEOS concentration, CTAB concentration, pH value) and objective functions ( Surface area and average pore size). The results show that the three factors have notable effects to the size of surface area, and the factor of pH value has more obvious effects to the size of pore diameter. By the way, the interactive effects to surface area are between TEOS concentration and pH value, and between CTAB concentration and pH value. However, for the size of pore diameter does not have apparent interactive effects. In this study, the Response Surface model was proposed to describe surface area and average pore size. From the analysis of variances and the determination coefficient, it demonstrated that experimental data were fitted well by the model.As to the objective function of the surface area, the optimization discussion was carried out. The result shows that the conditions of TEOS =0.027, CTAB =0.00835, pH value =1, can make silica gels at 1428m2/g high surface area. Finally, the water vapor equilibrium adsorption capacity was measured in this study for the prepared silica gel at the optimization condition.

並列關鍵字

Sol-Gel process ； Response Surface Methodology Surfactant ； Silica gel ； Adsorption capacity

參考文獻

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