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Mixed matrix membranes (MMMs) were fabricated by incorporating ZIF-8@GO into Pebax matrix to improve CO 2 separation performance. The ZIF-8@GO played multiple roles in enhancing membrane performance. First, the high-aspect ratio GO nanosheets in polymer matrix increased the length of the tortuous path of gas diffusion, restricting the diffusion of larger molecules and favoring the diffusion of small molecules with less resistance, which enhanced the diffusivity selectivity. Second, the inherent high permeability of ZIF-8 with ultra-microporosity was anticipated to optimize fractional free volume and enhance the gas permeability and solubility selectivity of MMMs. The MMMs doped with ZIG-8@GO had better gas separation performance than those doped with only ZIF-8 or GO. The membrane containing 6 wt% of ZIF-8@GO (Peabx/ZIF-8@GO-6) exhibited the optimum performance with a CO 2 permeability of 249 Barrer and a CO 2 /N 2 selectivity of 47.6. Compared with the pure Pebax membrane, the CO 2 permeability and CO 2 /N 2 selectivity of the Pebax/ZIF-8@GO-6 MMMs were increased by 191% and 174%, respectively. The strategy of growing ZIFs on GO may provide an effective method to further develop MMMs performance through the modification of ZIFs on existing fillers which had larger adsorption differences to specific gases. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO)-based nanofiltration membranes, featuring well-ordered microscopic structure, well-defined 2D nanochannels and superior molecular sieving ability, have attracted sustained research interest in molecular and ionic separation. However, most of current GO laminar membrane have a poor water flux and high rejection of both dyes and salts, which is not suitable for the dye/salt mixture separation. Herein, we report a vacuum filtration strategy to fabricate GO/NH 2 -Fe 3 O 4 nanofiltration membranes with high water flux and excellent separation performance for dye/salts mixture by introducing NH 2 -Fe 3 O 4. The NH 2 -Fe 3 O 4 is not only worked as the rigid spherical nanospacer to tune GO interlayer spacing but also as crosslinkers to improve the stability of GO membrane in water. FTIR, XRD, SEM, zeta potential and contact angle were applied to analyze the chemical composition and morphology of as-prepared membranes. The effect of intercalated NH 2 -Fe 3 O 4 nanoparticles on overall performance of the GO/NH 2 -Fe 3 O 4 membranes was systematically investigated. The resulted membrane with 8 wt% of NH 2 -Fe 3 O 4 loading has high water flux of up to 78 Lm−2 h−1, which is 4.8 times higher than that of pure GO membrane. Moreover, such membrane also displays high congo red rejection (94%) and low NaCl rejection (~15%), rendering the membranes promising for dye/salt mixtures separation. Intercalated NH 2 -Fe 3 O 4 can simultaneously tune the GO interlayer spacing and improve the stability of GO membrane in water. Unlabelled Image • GO/NH 2 -Fe 3 O 4 membranes were prepared for dye/salt mixture separation. • NH 2 -Fe 3 O 4 can simultaneously tune interlayer spacing and improve membrane stability. • GO/NH 2 -Fe 3 O 4 -8 membrane has high water flux and CR rejection but low NaCl rejection. [ABSTRACT FROM AUTHOR]

Inspired by biological membranes with charge-gated channels that allow the transport of water and ions but restrict the undesired substances, various regulated nanofiltration (NF) membranes containing charge-gated channels have been developed for water purification. However, most of these membranes are mono-charged (positively or negatively) that show high rejection only to the corresponding co-ions but low rejection to the counter-ions, which limits their wider applications. Herein, we report NF membranes with gas-tunable charge-gated channels and high rejection to different salts on demand. The membranes are prepared by assembling a CO 2 -responsive polymer, poly(N,N-dimethylaminoethyl methacrylate), on the surface of graphene oxide (GO). As a result of CO 2 -induced reversal of the charge sign, the membranes exhibit "self-regulation" of their surface charges. Upon bubbling CO 2 into water, the membranes are positively charged, which shows high rejection to MgCl 2. After bubbling Ar to remove CO 2 , the membranes gradually transform to negatively charged, and high rejection to Na 2 SO 4 is obtained. This study demonstrates the gas-tunable charge-gated ion transport behavior of the CO 2 -responsive NF membranes, and opens up new avenues for the design of on-demand NF membranes. New nanofiltration membranes exhibit on-demand switchable rejections toward cations and anions with the participation and departure of CO 2. Image 1 • New nanofiltration membrane was built with graphene oxide and CO 2 -responsive polymer. • The surface of nanopores can be reversibly switched between opposite charged state. • Charge sign can easily be reversed in a robust and contamination-free manner. • Ion transport behavior was dominated with the participation and departure of CO 2. [ABSTRACT FROM AUTHOR]

Incorporation of GO/PANI could enhance anticorrosion performance of WEP coating by synergetic effects between GO and PANI. • The prepared GO/PANI possesses an outstanding dispersibility in waterborne coatings. • The GO/PANI has excellent electrochemical properties and can significantly block the small molecules. • The preparation of GO/PANI/WEP coating is very simple. • The GO/PANI/WEP coating plays a remarkable anti-corrosion performance. • The GO/PANI/WEP coating is environmentally friendly owing to low volatile organic content. We reported the moderate synthesis of graphene oxide/polyaniline composite (GO/PANI) via in-situ polymerization. The Raman spectra, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) indicated that strong π-π interactions occurred between GO and PANI. The as-prepared composite showed the excellent water dispersion ability, remarkable electrochemical properties, outstanding water barrier effect and thermal stability, which made them appropriate as a corrosion inhibitor for waterborne anticorrosion coatings. Compared with pure waterborne epoxy (WEP) coating, the prepared GO/PANI/WEP coatings exhibited remarkably reinforced anticorrosion performances, which were confirmed by the results of the polarization curves and electrochemical impedance spectroscopy (EIS). The superior anticorrosion performances of GO/PANI/WEP coatings were mainly attributed to the synergistic effect of GO as the physical barrier and PANI as the conducting polymers. The strategy for in-situ polymerization of PANI on the GO provides an effective method to develop other GO/conducting polymers composites for the further applications in waterborne anticorrosion coatings. [ABSTRACT FROM AUTHOR]