•Inter-layer spacing of graphene oxide laminates were modified with solvent green.•The surface charge and hydrophilicity of GO membrane was improved.•The flux of SG modified GO membrane was increased by six times.In this study, the inter-layer spacing between graphene oxide (GO) layers were tuned with solvent green (SG) to enhance the nanofiltration performance of the laminar GO membranes. GO nanosheets were firstly modified by SG through the strong π-π stacking interactions. The SG@GO nanocomposites were then assembled onto the surface of tubular ceramic substrate through immersion method. The morphologies and structures of the resulting SG@GO composite membranes were characterized by scanning electron microscope (SEM), energy dispersive X-ray spectrometer (EDX), X-ray diffraction (XRD), and Fourier transform infrared (FTIR). The composite membrane was used for removing dye molecules (Eriochrome black T) from water. It was found from the results that the SG@GO composite membranes showed a flux of 330 L m−2 h−1 MPa−1, which was nearly 6-fold enhancement compared with that of the pristine GO membrane (56 L m−2 h−1 MPa−1), without sacrificing the dye rejection. Therefore, this strategy may provide a facile approach to tune the inter-layer spacing of GO laminates for efficient molecular separation.

•NH2-UiO-66/PEI MMMs were prepared for acetic acid dehydration.•The MMMs were deposited on surface of NaA zeolite tubular substrate.•The composite membrane showed good pervaporation performance.Acetic acid dehydration is significant in chemical industry. Pervaporation has attracted increasing attention due to its low energy consumption and environmentally friendly process. However, there is still lack of efficient membrane materials for the pervaporation separation of acetic acid/water mixtures. Therefore, developing new material to prepare pervaporation membrane is currently the main task. In this study, an acid stable Zr-MOF NH2-UiO-66 was synthesized and incorporated into poly(ethyleneimine) (PEI) to form mixed matrix membranes (MMMs) for separating acetic acid/water mixtures. The NH2-UiO-66/PEI MMMs were deposited on the surface of NaA zeolite tubular substrate to form composite membranes using dip-coating method. The morphologies and structures of the particles and composite membranes were characterized by SEM, EDX, FTIR and contact angle. The effects of membrane preparation conditions on the separation performance were investigated. The results indicated that the NH2-UiO-66/PEI composite membranes showed good acetic acid dehydration behavior, because of the high porosity and hydrophilicity of the particles. Moreover, the particles had good compatibility with polymer and strong combination with substrate. Therefore, this study may provide a new material and facile strategy for preparing composite membrane in the separation of acetic acid/water mixtures.

•Water was used as the solvent to fabricate hyperbranched polymer emulsion.•HBP micelles were controlled in water by varied concentrations.•The HBP composite membranes was used in separating aromatic/aliphatic mixtures.•PSI of the membrane formed using water as solvent was increased 3.3-fold than DMF.•The strategy is facile in pervaporation separation of aromatic/aliphatic mixture.The separation of aromatic/aliphatic mixtures is significant in chemical industry. Pervaporation has attracted increasing attention due to its low energy consumption and environmentally friendly process. However, the formation of membranes mostly use toxic organic solvents, whereas in this study water was used instead to prepare membrane in separating aromatic/aliphatic mixtures. W3000 were dispersed in water to form micelles, which were then deposited onto the surface of the tubular porous ceramic substrate through the negative pressure-driven assembly method. The emulsion and composite membranes were characterized by TEM, SEM and FTIR. The crosslinking density of W3000 was also tested using NMR XLD analyzing system. The membranes were used for separating aromatic/aliphatic mixtures through pervaporation. The results showed that compared with the membrane prepared by DMF, the pervaporation separation index (PSI) of the composite membrane formed using water as solvent was 3.3-fold increased for separating toluene/n-heptane mixtures. The as-prepared composite membranes showed a better comprehensive pervaporation performance. This facile strategy may have a potential in the application of pervaporation for separating aromatic/aliphatic mixtures in industry.In this study, a facile strategy was reported to prepare composite membranes for separating aromatic/aliphatic mixtures.Download high-res image (146KB)Download full-size image

The key to preparing dense composite membranes is reducing the thickness of the composite layer with stable separation performance. Herein, we report a nanoconfined composite membrane prepared by in situ growth of Zeolitic Imidazolate Framework (ZIF) nanocrystals in the nanoporous layer of the substrate via a fine-tuning contra-diffusion method. The thickness of the composite layer on the membrane surface was nearly zero. The formed ZIF nanoconfined composite membranes showed state-of-art flux and high stability in removing dyes from water. This new strategy is expected to offer great opportunities for the potential practical application of polymer-supported metal–organic framework (MOF) composite membranes.Keywords: high flux; nanoconfined membrane; nanofiltration; polymeric substrate; zero thickness; ZIF membrane

•Adsorption and diffusion properties of PEBA were determined by IGC technique.•PEBA/ceramic tubular composite membrane was fabricated by thermal crosslinking.•Aromatic/aliphatic separation by PEBA/ceramic tubular pervaporation membrane.Pervaporation could be a cost-competitive process for separating aromatic/aliphatic hydrocarbon mixtures in the chemical industry. In this study, commercial poly(ether-block-amide) (PEBA) and ceramic tubular substrates were used to prepare pervaporation membrane for separating aromatic/aliphatic mixtures through a facile thermal crosslinking method. The adsorption and diffusion properties of toluene and n-heptane in PEBA were determined by swelling experiment and inverse gas chromatography technique. FTIR and XRD were used to investigate the hydrogen bonding and crystallinity of PEBA molecule through thermal crosslinking. The morphology and structure of PEBA/ceramic composite membrane were characterized by SEM and EDX. The separation performance of the composite membrane can be adjusted by controlling PEBA concentration, thermal crosslinking temperature and time. Ceramic tubular substrate could suppress the excessive swelling and thereby enhance the stability of the membrane. Furthermore, different types of fillers were incorporated into PEBA matrix to improve the separation performance. The results demonstrate that PEBA/graphite hybrid membrane has the highest separation factor for separating 50 wt% toluene/n-heptane mixtures. This study is expected to extend the membrane material and simplify the membrane preparation procedures in aromatic/aliphatic pervaporation fields.