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This study focuses on enhancing the mechanical strength of aquaporin (AQP)-based biomimetic membranes for seawater desalination. AQP incorporated vesicles were embedded into the selective layer of an optimized thin film composite (TFC) membrane. The resultant membrane, denoted as ASW, exhibited a stable water flux around 20 L·m−2·h−1 and 99% NaCl rejection at a constant pressure of 55 bar using 32,000 mg·L−1 NaCl solution as feed in reverse osmosis (RO) measurement. The robustness of the ASW membranes were evaluated. The water flux of ASW membrane was almost 100% enhanced compared with that of AQP-free control TFC membranes. The filtration performance of the ASW membrane was further evaluated by a seven-day desalination test using a real seawater secondary effluent collected from a desalination plant in Singapore as feed. To our best knowledge, our study is the first report on the AQP-incorporated RO membrane applied for seawater desalination. A commercial SW30HR membrane was tested in parallel for comparison. The robust ASW membrane exhibited a nearly 80% higher water flux in comparison to the SW30HR membrane with a comparable overall solute rejection, suggesting the advantage and feasibility of Aquaporin based biomimetic membranes for seawater desalination. • The mechanical strength of aquaporin incorporated polyamide layer was characterized with AFM. • The effects of high pressure compaction and salinity on aquaporin incorporated polyamide layer were investigated. • The aquaporin based biomimetic membranes were optimized for seawater desalination (SWRO) application. • A seven-day SWRO measurement of the ASW was conducted using a real seawater secondary effluent. [ABSTRACT FROM AUTHOR]

Polymersomes-based reverse osmosis (RO) membrane (PBM) for desalination was reported for the first time. An amphiphilic tri-block copolymer, PMOXA 6 -PDMS 35 -PMOXA 6 (ABA) , was self-assembled to form polymersomes with spherical nanostructure. The polymersomes were then immobilized into a polyamide network via an interfacial polymerization reaction on top of polysulfone membrane substrate. Under a moderate salinity condition, the PBM presented almost doubled water permeability and higher salt rejection than the control membrane without polymersomes in the polyamide network. Based on the results of a series of characterization the better water permeation of the PBM is believed to result from larger globular features containing highly water permeable polymersomes, which created a higher void fraction in the selective layer, whereas the highly cross-linked polyamide selective layer as well as the polymersome bilayer’s impermeability to NaCl may led to the enhanced salt rejection. Surprisingly, at an elevated NaCl concentration up to 32,000 ppm, the PBM exhibited ~ 60% water flux enhancement and even better NaCl rejection as compared with commercial seawater RO membranes. In general, the PBM presented a water flux similar to the RO membranes with loose polyamide matrix (BW30), but a rejection behavior close to the dense RO membranes (SW30). This study provides a paradigm shift in developing new-generation RO membranes for energy and cost-effective desalination process. [ABSTRACT FROM AUTHOR]

In present study, we explored the fabrication of a high performance thin-film composite (TFC) forward osmosis (FO) membrane by minimizing the structural parameter of hollow fiber substrates and enhancing the water permeability of selective layer. A theoretical analysis specified that a minimized structural parameter of substrate combined with an enhanced water permeability of selective layer could generate a significantly high water flux in FO process. The experimental results showed that the addition of LiCl into polyetherimide (PEI) polymer dope made the membrane less tortuous and thereby significantly reduced the structural parameter. The elevated take-up speed reduced the substrate thickness but also made the substrate more tortuous. Further study showed that a robust hollow fiber with low structural parameter can be obtained by reducing the substrate wall thickness and dimension simultaneously. After optimization, the structural parameter of the substrate declined from 308 µm to 172 µm. After interfacial polymerization, the thin-film composite membrane constructed on the optimized substrate showed an improved water permeability (from 2.85 L m −2 h −1 bar −1 to 3.66 L m −2 h −1 bar −1 ) and a comparably low salt permeability (0.36 L m −2 h −1 versus 0.31 L m −2 h −1) . The low structural parameter, in combination with the high water permeability and low salt permeability, contributed to significantly increased water flux ( J v ) from 25.4 L m −2 h −1 to 38.5 L m −2 h −1 when 1 M NaCl was used as draw and deionised water as feed in a configuration of active layer facing feed solution (AL-FS). Furthermore, aquaporins were incorporated into the polyamide selective layer to enhance the water permeability, which remarkably reached up to 7.6 L m −2 h −1 bar −1 . The aquaporin-incorporated FO membrane demonstrated a J v of 49.1 L m −2 h −1 and a J s /J v ( J s indicates the salt flux) of 0.10 g/L with 1 M NaCl as draw and deionised water as feed in the AL-FS configuration, which is favourable to mitigate membrane fouling in practical application. The AQP-FO membrane reported in this study outperforms most of other reported FO membranes. [ABSTRACT FROM AUTHOR]