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Abstract: Highly hydrophobic surface property of membranes is very important for membrane contactor application that is normally used for CO2 capture. This study explores a simple and inexpensive approach for hydrophobic modification of imide group contained polymeric membranes. Poly(amide–imide) (PAI) hollow fiber membrane with controlled pore structure as porous substrate was fabricated by dry-jet wet spinning process, followed by a wet-chemical hydrophobic modification using octadecylamine. The modification mechanism was confirmed by ATR-FTIR, and the effect of different modification times on the modified membrane properties was investigated. Experiments reveal that the modification changed the membrane morphology and structure, resulted in surface pore opening and thinning down of the membrane skin layer. As a compromise between the membrane hydrophobicity and mechanical strength, 10–30min were considered as appropriate modification times for the PAI membranes. The treated membranes showed much higher hydrophobicity with an improvement in contact angle of around 30°. The liquid entry pressure (LEPw) also increased dramatically from 7psi to 63psi after 30min modification due to the enhanced membrane hydrophobicity. The treated membranes were tested in the membrane contactor for CO2 absorption. It was observed the CO2 flux increased with the liquid velocity and modification time. A stable long-term performance of CO2 absorption by a 2M sodium taurinate aqueous solution for 15days of operation was attained. Moreover, poly(etherimide) (PEI) hollow fiber membranes were successfully modified by octadecylamine, which demonstrated the effectiveness and versatility of the modification method on imide-contained polymeric membranes. [Copyright &y& Elsevier]

• Membranes containing SNW-1 nanoparticles and Co(acac) 3 were successfully fabricated. • Combined use of SNW-1 and Co(acac) 3 enhanced O 2 permeability and O 2 /N 2 selectivity. • Both solubility and diffision selectivity can be enhanced by Co(acac) 3 and SNW-1. Mixed-matrix membranes containing a porous organic framework (SNW-1 nanoparticles) and a cobalt-based complex (Co(acac) 3) were fabricated using the solution-casting technique for potential applications in O 2 /N 2 separation. The mixed-matrix membranes did not show any appreciable defects. In the following mixture gas permeation testing conducted with a binary mixture composed of 21% O 2 and 79% N 2 at 1 bar feed pressure and 35 °C, the mixed-matrix membranes containing SNW-1 nanoparticles showed an enhanced O 2 permeability, whereas Co(acac) 3 improved the O 2 /N 2 selectivity. Hence, with a combination of both nanoparticles and a Cobalt complex in a polymer matrix, a clear synergistic enhancement in O 2 /N 2 separation properties was reported, in which O 2 permeability and O 2 /N 2 selectivity were escalated by 33% and 18%, respectively. Solubility-diffusivity analysis in the mixed-matrix membranes revealed that SNW-1 and Co(acac) 3 can improve O 2 diffusivity and O 2 solubility, respectively, resulting in an enhancement of both O 2 permeability and O 2 /N 2 selectivity for membranes containing both the nanoparticles and the cobalt complex. Future efforts will be focused on developing asymmetric hollow fiber membranes with thin skin layer comprising both SNW-1 and Co(acac) 3. [ABSTRACT FROM AUTHOR]

In this study, the self-assembly of rare-earth Anderson polyoxometalates (POMs) on the surfaces of imide polymeric hollow fiber membranes was designed for fabrication of novel POMs-functionalized interfacial composite membranes. The rare-earth Anderson POM ([Gd(H 2 O) 7 Cr(OH) 6 Mo 6 O 18 ] n ) nanoparticles with controllable size and distribution were successfully constructed. Experimental results revealed that the self-assembly was a surface-induced growth process. The silanol groups on the membrane surfaces generated by the (3-aminopropyl)trimethoxysilane pretreatment were essential for the self-assembly process because of the potential hydrogen bonding ( OH⋯POMs) and coordination bonding ( OH Gd) interactions. This work provided a simple but practical method not only for the fabrication of novel POMs-functionalized membranes, but also for the synthesis of POMs nanoarchitectures. In addition, the potential application of the as-prepared POMs-functionalized hollow fiber membranes in degradation of organic pollutant has also been explored. The idea of interfacial membrane contactor has been utilized for the catalytic wet air oxidation of phenol under mild conditions. A three-phase (gas/catalyst/liquid) interface was successfully built up, which enhanced the catalytic efficiency. It is anticipated that these novel POMs-functionalized membranes can promisingly be used as catalytic membrane contactors for wastewater treatment under mild conditions. [ABSTRACT FROM AUTHOR]

Highlights: [•] Effect of intrinsic properties of foulants on FO membrane performance was studied. [•] Diffusivity governs hollow fiber membrane performance in FO mode. [•] Flat sheet membrane performance in PRO mode was controlled by combined mechanisms. [•] The mechanisms include diffusivity, size exclusion and electrostatic interactions. [ABSTRACT FROM AUTHOR]