A carbon nanotube filled polydimethylsiloxane hybrid membrane for enhanced butanol recovery

Abstract

The carbon nanotubes (CNTs) filled polydimethylsiloxane (PDMS) hybrid membrane was fabricated to evaluate its potential for butanol recovery from acetone-butanol-ethanol (ABE) fermentation broth. Compared with the homogeneous PDMS membrane, the CNTs filled into the PDMS membrane were beneficial for the improvement of butanol recovery in butanol flux and separation factor. The CNTs acting as sorption-active sites with super hydrophobicity could give an alternative route for mass transport through the inner tubes or along the smooth surface. The maximum total flux and butanol separation factor reached up to 244.3 g/m2·h and 32.9, respectively, when the PDMS membrane filled with 10 wt% CNTs was used to separate butanol from the butanol/water solution at 80°C. In addition, the butanol flux and separation factor increased dramatically as temperature increased from 30°C to 80°C in feed solution since the higher temperature produced more free volumes in polymer chains to facilitate butanol permeation. A similar increase was also observed when butanol titer in solution increased from 10 g/L to 25 g/L. Overall, the CNTs/PDMS hybrid membrane with higher butanol flux and selectivity should have good potential for pervaporation separation of butanol from ABE fermentation broth.

4. Introduction to bioconversion and downstream processing: principles and process examples

“…Promising approaches include pervaporation techniques or membrane techniques, since they work efficiently under fermentation conditions, like low temperature. For example, Xue et al [88] used membranes with incorporated carbon nanotubes instead of toxic and expensive ILs. Next to this, the heat and energy integration in a biorefinery is of major importance to create an autonomic and sustainable process.…”

Applied in situ product recovery in ABE fermentation

“…More recently, there has been a move toward the use of composite membranes, utilizing a combination of materials for improved selectivity and flux performance. This has included silicalite‐silicone composite membrane silicalite‐PDMS/polyacrylonitrile (PAN) membrane, PDMS/ceramic composite, zeolite‐mixed PDMS and carbon nanotube filled PDMS (CNT‐PDMS) . A wider range of membranes have been investigated for butanol/water or ABE/water solutions, but this does not necessarily transfer to the performance in conjunction with a fermentation …”

“…used a silicalite‐PDMS/PAN membrane and were able to achieve an average permeate concentration of 201 g ABE/L, resulting in spontaneous phase separation. Xue et al . used a CNT‐PDMS membrane.…”

“…This has included silicalite-silicone composite membrane 57 silicalite-PDMS/polyacrylonitrile (PAN) membrane, 58 PDMS/ceramic composite, 59 zeolite-mixed PDMS 60 and carbon nanotube filled PDMS (CNT-PDMS). 61 A wider range of membranes have been investigated for butanol/ water or ABE/water solutions, but this does not necessarily transfer to the performance in conjunction with a fermentation. 48 The membrane choice affects the selectivity and diffusion rates of the ABE, which will determine the concentration of the ABE in the permeate.…”

Shrinkage induced stretchable micro-wrinkled reduced graphene oxide composite with recoverable conductivity

“…As shown in Fig. 2B, to reach the same strain, more stress is required for the MWrGO/PDMS composite, showing the stiffness of PDMS matrix after MWrGO addition [38]. The reinforcement of PDMS by the incorporation of MWrGO may be attributed to a restricted movement of polymeric chains in PDMS [39].…”