Facile synthesis of Kevlar nanofibrous membranes via regeneration of hydrogen bonds for organic solvent nanofiltration

• Published in: Journal of membrane science 2019-03, Vol.573, p.612-620
• Main Authors: Yuan, Shushan, Swartenbroekx, Jasper, Li, Yi, Zhu, Junyong, Ceyssens, Frederik, Zhang, Ruijun, Volodine, Alexander, Li, Jian, Van Puyvelde, Peter, Van der Bruggen, Bart
• Format: Article
• Language: English
• Subjects: Kevlar; Nanofiber; Organic solvent nanofiltration; Poly(p-phenylene terephthalamide)
• ISSN: 0376-7388; 1873-3123
• DOI: 10.1016/j.memsci.2018.12.047

Polymeric organic solvent nanofiltration (OSN) membranes have gained increasing attention in OSN for their relatively low cost and ease of scaling up. However, fabrication processes are still complex, consume a large amount of aggressive solvents and sometimes even pose a safety risk in fabrication, resulting in a negative environmental impact and still having potential to lower the fabrication cost further. In this study, thin Kevlar nanofibrous organic solvent nanofiltration membranes were fabricated through a facile and green thermal treatment by using greener solvent. Instead of corrosive concentrated H2SO4, a greener solvent, i.e., a DMSO-KOH/water mixture was used to prepare a dope solution containing Kevlar nanofibers. Then, hydrogel ultrafiltration membranes were obtained from this dope solution by phase inversion. Subsequently, a facile thermal treatment in an oven was applied to transform the hydrogel ultrafiltration membrane into a solvent resistant nanofiltration membrane without consuming additional solvents and crosslinking agents by the regeneration of hydrogen bonds. The obtained nanofibrous membrane (M2%-200) has a Rose Bengal rejection of 95.4% and an ethanol permeation of 2.9 L/(m2 bar h), outperforming most other polymeric pristine OSN membranes prepared by phase inversion. This gives the Kevlar membrane a high baseline for further modification in order to increase the performance. In addition, Kevlar nanofiltration membranes maintain a relatively constant dye rejection during the filtration of a dye solution for 6 h and retain a dye rejection over 94% after being treated by different solvents for 7 days, indicating a very good solvent resistance. Moreover, this study not only provides a facile way of synthesizing Kevlar OSN membranes from a dope solution containing nanofibers, but also enables the fabrication and application of Kevlar threads in membranes by a non-corrosive and greener solvent, which may open up new insights and strategies to develop Kevlar into nanofiltration membranes. •Kevlar OSN membranes were prepared by a facile thermal treatment.•Compared to concentrated H2SO4, greener solvent, DMSO, was used to dissolve the Kevlar threads.•Hydrogel ultrafiltration membrane was prepared by phase inversion.•Unlike conventional polymeric membranes, Kevlar OSN membrane has a nanofibrous structure.•Kevlar membrane shows a rejection of 95% to Rose Bengal and ethanol permeation of 2.9 L m−2 h−1 bar−1.