(279e) The Vertically Aligned and Opened Carbon Nanotube Filled Polydimethylsiloxane Composite Membrane for Enhanced Butanol Recovery

Present polymeric membranes are well known to suffer from a tradeoff between selectivity and permeability, and in some cases are also susceptible to fouling or exhibit low chemical resistance. It is believed that, through a fundamental understanding of the relationship between their processing, structure and performance relationships, the creation of multifunctional composites with controlled hierarchical structures may offer a wide range of future applications. Vertically aligned (VA) and open-ended carbon nanotube (CNT) arrays filled polydimethylsiloxane (PDMS) composite membrane was prepared, characterized, and its potential for butanol recovery from acetone-butanol-ethanol (ABE) fermentation broth was evaluated. The butanol solubility and diffusivity of the VA CNT (open-ended)/PDMS membrane was higher than those of PDMS membrane, which contributed to a greater butanol flux and higher selectivity of the VA CNT (open-ended)/PDMS membrane than the PDMS membrane for the same butanol solution. The maximum total flux and butanol separation factor of the VA CNT (open-ended)/PDMS membrane reached up to 1093.7 g/m² h and 37.6 at 80 ℃, respectively. In addition, the butanol flux and separation factor increased dramatically as temperature increased from 30 ℃ to 80 ℃ in feed solution. A similar increase was also observed when the concentration of butanol in the solution increased from 5 g/L to 25 g/L. The presence of open-ended VA CNT arrays in the PDMS membrane led to increased butanol flux and separation factor, probably due to the smooth and hydrophobic surface and internal channel of the CNTs to facilitate butanol permeation across the membrane. The composite membrane was tested in fermentation broth and showed a stable performance for long time continuous operation, demonstrating its potential for practical application. Overall, the VA CNT (open-ended)/PDMS membrane with higher butanol flux and selectivity should have good potential for pervaporation separation of butanol from ABE fermentation broth.