Free-standing, thin-film, symmetric membranes: Next-generation membranes for engineered osmosis

• Published in: Journal of membrane science 2020-07, Vol.607, p.118145, Article 118145
• Main Authors: Phuntsho, Sherub, Kim, Jung Eun, Tran, Van Huy, Tahara, Shuji, Uehara, Naoki, Maruko, Nobuhiro, Matsuno, Hirozumi, Lim, Sungil, Shon, Ho Kyong
• Format: Article
• Language: English
• Subjects: Desalination; Engineered osmosis; Non-polyamide-based membrane; Self-standing membrane; Sulfonated poly ether ketone
• ISSN: 0376-7388; 1873-3123
• DOI: 10.1016/j.memsci.2020.118145

The support layer of an asymmetric thin-film composite membrane results in structural resistance (internal concentration polarization) that significantly undermines engineered osmosis. Increasing the porosity and reducing the thickness and tortuosity of the membrane support layer reduces structural resistance; however, internal concentration polarization still impacts membrane performance. A novel, ultrathin, free-standing and symmetric membrane has been synthesized using sulfonated polyether ketone and tested for forward osmosis applications. This membrane is composed of a protonic acid group containing an aromatic polyether resin with sulfonated structural units. Polyether ketone provides high mechanical strength essential for ultrathin free-standing membranes, while sulfonation enhances the membrane hydrophilicity. These sulfonated polyether ketone membranes show promising water flux performances with impressive mechanical strength under the hydraulic operating conditions used for a FO process. •Ultrathin and free-standing FO membrane was synthesized using SPEK polymer.•0.6 μm thick membrane showed FO water flux of 20.5 Lm−2h−1 with 1 M NaCl: DI.•The specific reverse solute flux of this 0.6 μm thick membrane was 1.2 gL-1.•Free-standing SPEK film exhibited adequate mechanical strength for FO operations.•Embedding polyester mesh enhanced mechanical strength without impacting FO water flux.