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This study examined the feasibility and performance of a nanochannel-based biomimetic membrane (NBM) for brackish reverse osmosis (RO) desalination. Two types of peptide-attached synthetic nanochannels, (pR)-pillar[5]arenes (pRPH) and (pS)-pillar[5]arenes (pSPH), were incorporated into liposomes. pSPH is a diastereomer of pRPH and was used as a negative control (i.e. mutant) to pRPH in this work. The nanochannel-containing liposomes (e.g. pRPH-liposomes) were then immobilized into the active layer of the RO membranes via in situ interfacial polymerization on the top of a polysulfone support membrane to form NBM-pRPH membranes. To maximize the potential and benefits of the NBM-pRPH membrane, the physical characteristics of the polyamide layer was further tuned using some additives and the eventual membrane was named as NBM-pRPH-A. The NBM-pRPH-A membrane exhibited a water permeability of 6.09 L m−2 h−1 bar−1 and 98.2% NaCl rejection under a 15.5 bar applied pressure using 2000 mg L−1 as feed solution. The 62% flux increment with respect to the pristine control is postulated to arise from a thinner, less cross-linked (more free volume) and more hydrophilic active layer as well as the possible supplementary transport pathways of the pRPH-liposomes. The performance of the NBMs under differential feed pressures and temperatures further exemplifies the water permeation property of the pRPH nanochannels. Accordingly, the NBM-pRPH-A gave a water permeability higher than commercial RO membranes tested in this work (DuPont BW30 and Hydranautics ESPA2) as well as other RO membranes reported in the literature. This study provides a tangible foundation for the development of NBMs for brackish RO desalination. [Display omitted] • Synthetic pRPH nanochannel-based biomimetic membrane was used for BWRO application. • pRPH-liposomes were incorporated onto the PA layer via interfacial polymerization. • STEM-EDX analysis revealed the existence of liposomes in the PA layer. • High permeability of 6.09 Lm−2h−1bar−1 (98.2% NaCl rejection) was reported in BWRO. • RO tests under increasing ΔP and temperature suggested water transport across pRPH. [ABSTRACT FROM AUTHOR]

Although a highly porous support membrane has attracted increasing attention as an alternative to enhance the water permeability of a thin-film composite (TFC) membrane without compromising salt rejection, its feasibility has not ever been tested in seawater desalination. This study explored the availability and potential of a highly porous microstructured (HPμS) support membrane as a support for a seawater reverse osmosis (SWRO) membrane. Our lab-made membranes, TFC-HPμS, exhibited a higher water permeability of 1.62 L m−2 h−1 bar−1 as compared with most of the state-of-the-art SWRO membranes recently reported in the literature, while achieving comparable NaCl rejection (99%) in SWRO test condition (55 bar, 35,000 mg L−1 of NaCl). This excellent performance is thought to stem from the HPμS support endowing a TFC membrane with comparable mechanical properties to that of existing support used for conventional SWRO membrane and shortened effective diffusion pathway of water molecules over the active layer. The robustness and enhanced mechanical strength of the TFC-HPμS membrane are attributed to its narrow and regularly arranged finger-like structure ensuring the even distribution of local stresses, thereby eliminating the presence of stress convergence points. The shortened effective diffusion pathway was estimated to be achieved mainly by less localized surface pores due to the HPμS support's highly porous surface with a larger number of even distributed surface pores. This study potentially opens up another workable pathway in the fabrication of SWRO membranes with enhanced performance without significant sacrifice of the selectivity. • Highly porous microstructured support membrane was used for seawater desalination. • The regularly arranged sublayer enhanced the mechanical strength of the support. • The effective diffusion pathway can be shortened with less localized surface pores. • The tuned TFC membrane exhibited higher permselectivity as compared to the control. • High permeability of 1.62 Lm−2h−1bar−1 (>99% NaCl rejection) was reported in SWRO. [ABSTRACT FROM AUTHOR]