Acetone, butanol and ethanol (ABE) mixture separation from dilute aqueous fermentation products is an important process for the biofuel industry. Here, we present a novel approach for ABE recovery using microwave induced membrane distillation (MD). Carbon nanotubes (CNTs) and octadecyl amide (ODA) functionalized CNTs were immobilized on membrane surfaces and were used in sweep gas MD separation of ABE. The ABE flux, separation factor and mass transfer coefficient obtained with CNT and CNT-ODA immobilized membranes were remarkably higher than those of the commercial pristine membrane under various experimental conditions. The ABE flux enhancement reached as high as 105, 100 and 375% for the CNIM and 63, 62 and 175% for CNIM-ODA respectively. The ABE flux obtained was nearly ten times higher than that reported previously for pervaporation. The mass transfer coefficient also increased significantly along with a lower activation energy for the modified membranes. Mechanistically speaking, the immobilization of carbon nanotubes on the active membrane layer led to preferential sorption of ABE leading to enhanced separation. This phenomenon has been validated by the reduction of contact angles for the aqueous ABE mixtures on the CNT and CNT-ODA immobilized membranes indicating enhanced interaction of ABE on the membrane surface.

中文翻译：

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通过固定在碳纳米管上的微波诱导膜蒸馏，低温回收丙酮-丁醇-乙醇（ABE）发酵产品

从稀水发酵产物中分离丙酮，丁醇和乙醇（ABE）混合物是生物燃料工业的重要过程。在这里，我们提出了一种使用微波诱导膜蒸馏（MD）回收ABE的新方法。将碳纳米管（CNT）和十八烷基酰胺（ODA）官能化的CNT固定在膜表面，并用于吹扫气MD分离ABE。在各种实验条件下，用CNT和CNT-ODA固定化膜获得的ABE通量，分离因子和传质系数均明显高于市售原始膜。CNIM的ABE通量增强分别高达105、100和375％，CNIM-ODA分别达到63、62和175％。所获得的ABE通量比以前报道的全蒸发通量高近十倍。传质系数也显着增加，同时改性膜的活化能降低。从机理上讲，将碳纳米管固定在活性膜层上会导致ABE的优先吸附，从而增强分离效果。该现象已通过减小水性ABE混合物在CNT和CNT-ODA固定膜上的接触角而得到证实，表明ABE在膜表面的相互作用增强。