40 research outputs found

    Adjustable Functionalization of Hyper-Cross-Linked Polymers of Intrinsic Microporosity for Enhanced CO2 Adsorption and Selectivity over N2 and CH4

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    In this paper, we report the design, synthesis, and characterization of a series of hyper-cross-linked polymers of intrinsic microporosity (PIMs), with high CO2 uptake and good CO2/N2 and CO2/CH4 selectivity, which makes them competitive for carbon capture and biogas upgrading. The starting hydrocarbon polymers’ backbones were functionalized with groups such as −NO2, −NH2, and −HSO3, with the aim of tuning their adsorption selectivity toward CO2 over nitrogen and methane. This led to a significant improvement in the performance in the potential separation of these gases. All polymers were characterized via Fourier transform infrared (FTIR) spectroscopy and 13C solid-state NMR to confirm their molecular structures and isothermal gas adsorption to assess their porosity, pore size distribution, and selectivity. The insertion of the functional groups resulted in an overall decrease in the porosity of the starting polymers, which was compensated with an improvement in the final CO2 uptake and selectivity over the chosen gases. The best uptakes were achieved with the sulfonated polymers, which reached up to 298 mg g–1 (6.77 mmol g–1), whereas the best CO2/N2 selectivities were recorded by the aminated polymers, which reached 26.5. Regarding CH4, the most interesting selectivities over CO2 were also obtained with the aminated PIMs, with values up to 8.6. The reason for the improvements was ascribed to a synergetic contribution of porosity, choice of the functional group, and optimal isosteric heat of adsorption of the materials

    Membranes with Intrinsic Micro-Porosity: Structure, Solubility, and Applications

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    Microporous polymer membranes have been widely studied because of their excellent separation performance. Among them, polymers of intrinsic micro-porosity (PIMs) have been regarded as a potential next-generation membrane material for their ultra-permeable characteristics and their solution-processing ability. Therefore, many reviews have been reported on gas separation and monomers for the preparation of PIMs. This review aims to provide an overview of the structure-solubility property. Different structures such as non-network and network macromolecular structure made of different monomers have been reviewed. Then their solubility with different structures and different separation applications such as nanofiltration, pervaporation, and gas/vapor separation are summarized. Lastly, we also provide our perspectives on the challenges and future directions of the microporous polymer membrane for the structure-property relationship, anti-physical aging, and more

    Separation of acetone, butanol and ethanol (ABE) from dilute aqueous solutions by silicalite-1/PDMS hybrid pervaporation membranes

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    To study the effects of different factors on the separation of acetone, butanol, and ethanol (ABE) from ABE-water solutions by pervaporation with silicalite-l/polydimethylsiloxane (PDMS) hybrid membranes, the adsorption of ABE in the silicalite-1 in acetone-butanol-water solution and ethanol-butanol-water solution was firstly investigated and then the separation of ABE from binary aqueous solutions at different feed concentrations and temperatures was examined. Experimental results showed that butanol could be preferentially adsorbed on silicalite-1 and the permeability of acetone through the membrane was the highest, followed by butanol and ethanol, which was not consistent with the predictions based on the experimental results of adsorption and membrane swelling measurement. This could be explained by Hansen solubility parameters for the component and polymer interactions (delta(m,c)) and for the organic solvent and water interactions (delta(w,i)). In the separation of ABE-water solution by the silicalite-1/PDMS hybrid pervaporation membranes, acetone and ethanol could promote ABE transport through membrane and block water permeation, and the membrane performance could be significantly affected by vacuum pressure in the permeate side. (C) 2011 Elsevier B.V. All rights reserved

    Modification of silicalite-1 by vinyltrimethoxysilane (VTMS) and preparation of silicalite-1 filled polydimethylsiloxane (PDMS) hybrid pervaporation membranes

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    In preparation of inorganic particles filled polymer membranes, coupling agents can help to improve the compatibility between inorganic filler and polymer matrix. In this paper, surface modification of silicalite-1 was performed by a coupling agent, vinyltrimethoxysilane (VTMS), and hybrid pervaporation membranes were prepared by incorporating the unmodified or VTMS-modified silicalite-1 into polydimethylsiloxane (PDMS). The VTMS-modified silicalite-1 particles and hybrid membranes were characterized by FT-IR, (29)Si CP MAS NMR, DSC, TGA, XRD and SEM. The results showed that the coupling agent VTMS was readily grafted on the surface of silicalite-1 by hydrolysis reaction and condensation reaction, and the chemical linking between the -CH=CH(2) group on the surface-modified silicalite-1 and -Si-H on the PDMS substantially eliminated the nonselective voids inside the membrane. When used to separate acetone, butanol, ethanol (ABE) from aqueous solution, a higher selectivity was obtained with the VTMS-modified silicalite-1/PDMS hybrid membrane. Moreover, the surface modification of silicalite-1 improved its dispersion in PDMS and increased the maximal loading of silicalite-1 in membrane preparation, and thus further enhanced the separation factor of the membrane. (C) 2010 Elsevier B.V. All rights reserved

    Self-Catalytic Membrane Photo-Reactor made of Carbon Nitride Nanosheets

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    In this study we use a membrane photo-reactor (MPR) made of nanosheets of graphitic carbon nitride (g-C3N4), assembled by vacuum filtration, to make low-cost, efficient, easy-to-produce self-catalytic photo-reactors for water treatment under visible light.</p
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