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Abstract A new mixed protonic-electronic conducting material, Nd 5.5 W 0.35 Mo 0.5 Nb 0.15 O 11.25-δ (NWMN), was developed by Nb-doping to improve the hydrogen permeability of Nd 5.5 W 0.5 Mo 0.5 O 11.25-δ (NWM). The hydrogen permeation properties and stability of the NWMN were investigated in details. An enhanced hydrogen permeation flux through the NWMN membrane was achieved, which was about 2.5 times as high as that through the un-doped NWM membrane at 800 °C due to the increased ambipolar conductivity. Moreover, the phase structures of the NWMN powder and membrane remained unchanged after the treatment in pure CO 2 and H 2 -containing atmospheres, respectively, which reveals excellent stability of the NWMN powder in CO 2 and H 2 -containing atmospheres. The remarkable stability and improved hydrogen permeability make NWMN promising for the application of hydrogen separation. Highlights • A new H 2 permeable material, Nd 5.5 W 0.35 Mo 0.5 Nb 0.15 O 11.25-δ (NWMN), was developed. • Nb-doping is applied to enhance H 2 permeability of Nd 5.5 W 0.5 Mo 0.5 O 11.25-δ (NWM). • H 2 flux through NWMN membrane is ∼2.5 times as high as that through un-doped NWM. • The NWMN membrane shows excellent stability in CO 2 atmosphere. [ABSTRACT FROM AUTHOR]

Abstract: Sulfonated polybenzothiazoles with benzimidazole moieties were successfully prepared by polycondensation. For comparison purpose, sulfonated polybenzothiazoles were also synthesized. Rigid-rod sulfonated polybenzothiazoles generally show poor solubility in organic solvents, whereas these sulfonated polybenzothiazoles with high sulfonation degree are soluble, but the membranes cast from them swell excessively in water. Thus they could not be used as proton exchange membranes (PEMs). The comparison study demonstrates that the incorporation of benzimidazole moieties to sulfonated polybenzothiazoles greatly enhances the solubility of products. The resulting copolymers thus could be cast into the membranes as PEMs. The benzimidazole moieties in the resulting polymers improve thermal properties, dimensional stability, tensile strength, Young''s modulus, and oxidative stability, but they decrease proton conductivity and the elongation at break, due to the ionic cross-linking and hydrogen bonds. Even so, sulfonated polybenzothiazoles with appropriate content of benzimidazole moieties (10mol%) could still display a high proton conductivity of 0.094Scm−1 at 80°C and an elongation at break of 26.1%. These ionomers exhibited excellent overall properties such as excellent mechanical properties, high thermal and oxidative stability, low swelling, and high proton conductivity, thus they might be a candidate for proton exchange membranes. [Copyright &y& Elsevier]

Hybrid WS 2 /GO two-dimensional membranes were developed to achieve finely molecular sieving. The size of nanochannels in WS 2 membrane became smaller and more regular after the introduction of GO nanosheets into WS 2 membrane according to XRD and separation results. The hydrated hybrid WS 2 /GO membrane with 15 wt% GO (GO15WS 2) exhibited high rejection (>90%) for dyes and ions with a hydrated radius above 4.9 Å. A water permeance of 159.6 L/m2·h·bar and a Methylene Blue (MnB) rejection of 96.3% were achieved through hydrated hybrid GO15WS 2 membrane, which was excellent compared with reported two-dimensional membranes based on TMDs. Moreover, the nanochannels in GO15WS 2 membrane also presented strong rigidity under a pressure loading up to 0.5 MPa. In addition, the half-dried GO15WS 2 membrane possessed high tolerance to shear stress, and the separation performance changed slightly during a 120 h-cross-flow filtration, which made the hybrid GO15WS 2 membrane promising in water filtration. • Hybrid 2D WS 2 /GO membranes with regular nanochannels were constructed. • Separation performances of WS 2 membrane were improved after GO intercalation. • GO15WS 2 membrane could separate molecules with hydrated radius above 4.9 Å. • Half-dried GO15WS 2 membrane possessed excellent stability against shear force. [ABSTRACT FROM AUTHOR]

Abstract The PVDF membranes were prepared via thermally induced phase separation (TIPS) method with saline water as quenching bath and applied to the separation of oil/water emulsions. Surface pore size, permeation performance and other properties of the PVDF membranes were finely tuned by adjusting salt concentration in quenching bath. The results show that with the addition of NaCl in quenching bath, the thermal transfer resistance increases in the TIPS process due to the obvious increase of bath viscosity and the slight decline of thermal conductivity of saline solution. All the PVDF membranes present bi-continuously fibrillar structure in top surfaces. The fibrils are fused together and get thicker, and leads to rougher top surfaces due to the decline of cooling rate with the addition of NaCl in quenching bath. At the same time, the PVDF membranes exhibit expanded pore size and higher permeation flux for both pure water and oil/emulsions. The PVDF membrane of S20 (prepared with 20 wt% NaCl aqueous solution as quenching bath) exhibits the largest mean pore size and the highest pure water permeation flux of 2481.1 L m−2 h−1 bar−1. However, overhigh NaCl content leads to the inverse trend. For example, the PVDF membrane of S30 (quenching bath containing 30 wt% NaCl) exhibits a lightly decreased pore size and pure water permeation flux compared to S20. All of the PVDF membranes exhibit good oil rejections above 90.0% for surfactant-stabilized oil-in-water emulsions and above 95.0% for surfactant-free oil-in-water emulsions. Highlights • PVDF membranes are prepared via TIPS method with saline water as quenching bath. • Pore size and permeation performances of PVDF membranes are finely tuned. • Thermal transfer resistance rises with the increase of NaCl concentration. • Pore size of PVDF membranes increases with the increase of salt concentration. • Permeability of PVDF membranes increases with the increase of salt concentration. [ABSTRACT FROM AUTHOR]

Permeability and mechanical strength normally present an opposite trend for separation membranes. There is a trade-off line of permeability vs. tensile strength for the prepared poly(vinylidene fluoride) (PVDF) membranes via thermally induced phase separation (TIPS) method. In this work, TIPS-prepared PVDF membranes were fabricated with water (PVDF T-water) and air (PVDF T-air) as quenching bath for comparatively studying. PVDF T-air membranes present larger average pore size, higher permeability and better mechanical strength than those of PVDF T-water membranes due to the lower cooling rate of air bath. It is wonderful that all PVDF T-air membranes can break though the trade-off line of permeability vs. tensile strength of TIPS-prepared PVDF membranes. The optimal membrane (M-A30) shows superior performance, such as ultrahigh water flux of 3275 L m−2 h−1·bar−1 and tensile strength of 5.7 MPa. Additionally, this research provides a feasible method to regulate the morphology, pore size and permeability of TIPS-prepared PVDF membranes. • PVDF membranes (PVDF T-air) are prepared via TIPS method with air quenching bath. • PVDF T-air membranes overcome the upperbound of permeability vs. tensile strength. • PVDF T-air membranes have much higher permeability than PVDF T-water membranes. • Pore size increases with the increase of quenching temperature. [ABSTRACT FROM AUTHOR]

Janus membrane is an emerging separation material due to its unique separation performance. The asymmetric surface wettability on its two surfaces is crucial for a Janus membrane. In this work, robust Janus polyvinylidene fluoride (PVDF) membranes were prepared via thermal induced phase separation (TIPS) accompanied with spray-coating method. The two surfaces of TIPS-prepared PVDF membranes were rapidly deposited with polydopamine/polyethyleneimine (PDA/PEI) and micro-/nano-scale silica particles crosslinking with diphenyldichlorosilane respectively. The spray-coating endows the Janus membranes with superhydrophilicity and superhydrophobicity on its opposite surfaces. The optimized membrane of M-A0.9B0.2 presents an asymmetric surface wettability. Its hydrophilic surface has a water contact angle (WCA) of 11.2°, while the hydrophobic surface has a WCA of 169.9° as well as a sliding angle of <1°. The superhydrophilic surface allows water to quickly pass through the membrane and oil phase is trapped; while oil can penetrate through the membrane and water is rejected by the superhydrophobic surface. The Janus membranes show excellent separation performance with the highest permeation of 2060.5 L m−2 h−1·bar−1 accompanied with above 94.0% oil rejection for toluene-in-water emulsion and the highest permeation of 1769.0 L m−2 h−1·bar−1 accompanied with above 97.0% water rejection for water-in-toluene emulsion using the opposite surfaces. Image 1 • A robust Janus membrane with TIPS-prepared PVDF substrate. • Superhydrophilic and superhydrophobic opposite surfaces were constructed. • The Janus membrane can efficiently separate both O/W and W/O emulsions. [ABSTRACT FROM AUTHOR]