本研究主要探討結晶紫及鹼性紅9在原始多壁奈米碳管及硝酸氧化過後多壁奈米碳管上的吸附及脫附之機制。對於奈米碳管的基本特性分析主要通過穿透式電子顯微鏡，比表面與孔隙度分析儀，熱重分析儀以及傅利葉轉換紅外光譜儀。氧化過後的奈米碳管其比表面積略高於原始奈米碳管，兩者的孔洞面積均主要來自于中孔。原始奈米碳管表面含有一部份羥基及羧基，氧化過後明顯增加了其羥基及羧基的含量。本研究中所有吸附及脫附的動力學實驗都在非常短時間內達到平衡，並符合擬二階吸附模式。另外，本研究中的所有吸附等溫實驗均符合Langmuir吸附模式。吸附容量方面，結晶紫在原始奈米碳管上最高，鹼性紅9在原始奈米碳管上次之，鹼性紅9在氧化過後奈米碳管上最低，造成這一現象的原因主要是由於吸附質的三維立體分子結構所帶來的空間位阻效應。脫附的遲滯現象僅在鹼性紅9的脫附實驗中發生，並未在結晶紫的脫附實驗中觀察到，這表明其脫附遲滯是由於鹼性紅9的胺基與碳管表面的羧基所形成的不可逆酰胺鍵。另外通過超音波震盪前後的脫附實驗對比排除了分子截留作用在脫附遲滯中的影響。;Batch adsorption and desorption experiments of crystal violet (CV) and basic red 9 (BR9) on multiwalled carbon nanotubes (MWCNTs) were conducted in this study. The characteristics of MWCNTs after oxidation by nitric acid (O-MWCNTs) as well as as-purchased MWCNTs (A-MWCNTs) were analyzed by transmission electron microscope, accelerate surface area and porosimeter system, thermogravimetric analysis, and Fourier transform infrared spectrophotometer. The surface area of O-MWCNTs was slightly higher than that of A-MWCNTs and mesopore contributed most in the pore area of both MWCNTs. O-MWCNTs contained more hydroxyl group and carboxyl group than A-MWCNTs due to the nitric acid treatment. All adsorption and desorption kinetics in this study reached equilibrium quite rapidly and fitted well by pseudo-second-order model while all adsorption isotherms were fitted well by Langmuir model. The adsorption capacity decreased in the order of CV on A-MWCNTs, BR9 on A-MWCNTs, and BR9 on O-MWCNTs, which indicated that the steric hindrance caused by the three-dimensional structure of adsorbates played an important role in the adsorption process. Desorption hysteresis observed on BR9 but not on CV. The hysteresis might be caused by the irreversible amide bond between BR9 and the surface groups of CNTs.
