異丙醇為揮發性有機污染物之一，近年來成為高科技產業清洗製程中，主要使用之溶劑。就揮發性有機污染物控制技術中，利用吸附劑來處理揮發性有機物，是常見且經濟可行之方法，將空氣污染物吸附於吸附劑上，乾淨的氣體則排放至大氣中，其吸附劑脫附再生可利用變溫或變壓的程序。熱脫附程序中為了產生高溫的氣體或蒸汽，需要額外的能量消耗，且升溫或降溫時間長；變壓程序則是利用真空泵浦維持低壓狀態，使污染物脫附，相對的也需要增加能量的消耗與操作成本。而利用非熱電漿(Non-thermal plasma)產生高能量的電子與激發分子撞擊吸附劑中污染分子，使污染物分子脫離吸附劑達脫附之目的，且非熱電漿可操作於室溫與常壓下，快速啟動且無需維持高溫等優點，是一項新穎的技術。本研究使用顆粒狀活性碳吸附異丙醇，以不同脫附氣體於非熱電漿進行脫附效能之探討，脫附氣體分別使用氮氣、空氣與氧氣。結果顯示，氮氣為脫附氣體時，異丙醇脫附濃度降為零的時間最長為85分鐘，其依序為空氣的50分鐘與氧氣35分鐘。異丙醇脫附效率方面，氮氣為脫附氣體時最高，異丙醇脫附效率達82.14%，最低則為氧氣34.34%，於相同脫附時間15及30鐘時間下，異丙醇脫附效率仍以氮氣為脫附氣體時最高(37.18 %及57.88 %)。副產物方面，空氣與氧氣為脫附氣體時均有生成丙酮與CO2，氧氣則有CO生成，氮氣並無觀察到副產物生成，主要以異丙醇為主。脫附氣體流率增加異丙醇脫附效率提升5.1~8.4%，副產物選擇性下降。經重覆吸/脫附實驗後吸附劑BET比表面積下降平均孔洞尺寸上升，表面含氧官能基數量則增加，使用氮氣為脫附氣體，吸附劑表面積、平均孔徑及官能基變化最小。 How to effectively reduce volatile organic compound (VOC) emission into atmosphere has become an important environmental issue. Adsorption is commonly used as a control technique for reducing VOC emissions. Activated carbon and molecular sieve are generally used as absorbent materials which can be regenerated by desorption process either via temperature swing or pressure swing. However, these processes require additional energy for creating high temperature gas or low-pressure condition needed for desorption. A novel technique applying nonthermal plasma for effective desorption of VOCs from the absorbent materials by high energy electron impacts and excited molecules interaction is developed. This study evaluates the effectiveness of nonthermal plasma as a tool for the desorption of IPA from the bead-shaped activated carbon. The experimental results indicate that the IPA desorption efficiency obtained by different background gas are in the order as：N2 (82.14%) > AIR (47.05%) > O2 (34.34%), the products detected after plasma desorption include CO2, CO, and acetone when air or oxygen is used. The IPA desorption efficiency increases by approximately 5.1~8.4 % as the background gas flow rate is increased from 1000 to 2000 sccm. The BET surface area of bead-shaped activated carbon after repeated adsorption and plasma desorption decreases while the average pore diameter increases, and the amount of oxygen functional groups at surface increase as well.
