Development of cellulose triacetate asymmetric hollow fiber membranes with highly enhanced compaction resistance for osmotically assisted reverse osmosis operation applicable to brine concentration

• Published in: Journal of membrane science Vol. 653; p. 120508
• Main Authors: Nakao, Takahito, Goda, Shohei, Miura, Yuki, Yasukawa, Masahiro, Ishibashi, Miharu, Nakagawa, Keizo, Shintani, Takuji, Matsuyama, Hideto, Yoshioka, Tomohisa
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 05.07.2022
• Subjects: Cellulose acetate; Compaction resistance; Hollow fiber asymmetric membrane; Osmotically assisted reverse osmosis; Raman spectroscopy; Hollow fiber asymmetric membrane; Compaction resistance; Cellulose acetate; Raman spectroscopy; Osmotically assisted reverse osmosis
• ISSN: 0376-7388; 1873-3123
• DOI: 10.1016/j.memsci.2022.120508

Osmotically assisted reverse osmosis (OARO) has been recently proposed for concentrating high-salinity brines. The long-term performance stability of the membrane is essential for OARO, considering the long-term commercial operation. In this study, we developed hollow fiber membranes for OARO operation made of cellulose triacetate, and elucidated the relationship between the membrane structure and resistance to compaction against long-term operation under high pressure at 7.0 MPa. The mechanical properties and the performance of membranes operated under reverse osmosis (RO) conditions were very well correlated with the long-term performances and dimensional stabilities of membranes operated under OARO conditions. Raman spectroscopy revealed the asymmetricity difference of the membranes before and after long-term operation. Finally, operation for more than 700 h under OARO conditions was performed using commercial-sized membrane modules, and this result was as expected based on results from laboratory-scale membrane modules. The membrane developed for higher compaction resistance retained 95% water permeance even after operation for 700 h. This study clearly showed a relationship between the resistance to compaction and the membrane structure, both of which are important for practical OARO operation. [Display omitted] •CTA hollow fiber asymmetric membranes were prepared by NIPS for OARO.•The membrane showed great compaction resistance under high pressure at 7.0 MPa.•Relationship between membrane structure and compaction resistance was elucidated.•The membrane retained 95% water permeance even after OARO operation for 700 h.