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A novel pyrimidine-bridged organoalkoxysilane precursor, 4,6-bis(3-triethoxysilyl-1-propoxy)-1,3-pyrimidine (BTPP), was synthesized via a platinum-catalyzed reaction and subsequently a BTPP membrane was developed via a sol-gel process. This new membrane exhibits great potential for improved CO 2 separation compared with common amine-functionalized organosilica membranes. Possible CO 2 transport mechanisms across amine-functionalized organosilica membranes were explored by comparing the CO 2 sorption behaviors of organoalkoxysilane materials with both strong and mild affinities. The results showed that a membrane with strong affinity to CO 2 does not lead to a superior CO 2 separation capability. Hence, the concept of a “mild-affinity membrane” was proposed, which describes membranes with intermediate-to-low CO 2 binding energy that exhibits an improved level of CO 2 transport efficiency. The concept of a mild-affinity membrane offers the development of technological innovation leading to the realization of highly efficient CO 2 separation membranes. [ABSTRACT FROM AUTHOR]

[Display omitted] • A comprehensive study of naphtha separation by a series of adsorbents. • Influence of pore structure on the separation of real naphtha mixtures. • Influence of separation mechanism on the separation of naphtha mixtures. Naphtha separation is of significant importance for refineries to make full use of oil and to reduce the cost of refining. In the recent years, scientists have devoted great efforts to developing novel porous materials such as metal-organic frameworks (MOFs) for the separation of naphtha. However, previous investigations have been limited to single-component or 3- to 5-component model systems. Separation of full range hydrocarbon mixture such as naphtha has rarely been explored. In this work, we carry out a comprehensive study on the separation of alkane isomers as well as full range naphtha mixture by a series of robust microporous MOFs, e.g., Zr-abtc, Al-bttotb, Co-fa, in comparison with representative zeolite materials, e.g., ZSM-5 and zeolite 5A. We find that Al-bttotb and Co-fa, which can separate monobranched and dibranched alkanes through complete molecular exclusion, show superior separation performance for naphtha mixtures. This work may shed light on strategies for developing adsorbents with optimal performance for naphtha separation and ultimately realizing the industrialization of MOF-based separation technologies. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ultra-thin CHA and FAU membranes were evaluated for desalination by pervaporation. • The observed water flux was 24 kg/(m2‧h) for CHA and 28 kg/(m2‧h) for FAU membranes. • The effect of the support was estimated using a mathematical model. • The water flux could be much higher without the effect of the support. In the present work, ultra-thin zeolite CHA and FAU membranes, with thicknesses of 600 and 500 nm, respectively, were evaluated for desalination by pervaporation at various temperatures. Single gas permeation experiments were employed to verify high quality of the membranes. At 90 °C, the observed water fluxes for CHA and FAU membranes were as high as 24 and 28 kg/(m2‧h), respectively. A mathematical model was used to estimate the effect of the support. The results showed that the mass transfer resistance of the support reduced the flux. The water flux corrected for the mass transfer resistance over the support was as high as 40 and 51 kg/(m2‧h) at 90 °C for CHA and FAU membranes, respectively. To the best of our knowledge, these are the highest reported water fluxes for desalination by zeolite membranes in a pervaporation process. [ABSTRACT FROM AUTHOR]

Ultra-thin MFI membranes (0.5 μm) were evaluated for recovery of alcohols from dilute aqueous mixtures by pervaporation at high temperature and pressure for the first time. The feed pressure was sufficiently high to keep the feed in liquid state at high temperature, while the permeate pressure was kept at atmospheric and a low flow of sweep gas was used to reduce the partial pressure on the permeate side. Atmospheric pressure on the permeate side is more practical than vacuum. High feed temperature and pressure result in high fugacity in the liquid feed, which, in combination with lower permeate pressure, results in a large driving force. Consequently, the membrane exhibited very high fluxes for feeds comprised of 10 wt% ethanol/water and 5 wt% n -butanol/water mixtures at 110 °C and 140 °C, respectively. The flux observed for 10 wt% ethanol/water mixtures was as high as about 52 kg m −2 h −1 , i.e., 6 times higher than the highest previously reported flux for this separation using zeolite membranes in pervaporation. For 5 wt% n -butanol/water mixtures, the flux was 40 kg m −2 h −1 , which is 11 times higher than the highest previously reported flux for this separation by zeolite membranes. At these conditions, the membrane displayed separation factors for ethanol/water and n -butanol/water mixtures of 5 and 16, respectively. However, after about 6 h of operation, the separation factor decreased significantly and the flux increased due to formation of defects in the membrane when the feed was saturated with silica. Lower membrane stability was observed for silica free feeds. The work has shown that it is possible to obtain high flux in pervaporation by using ultra-thin membranes in combination with high feed temperature. The observed membrane selectivity was not excellent, due to pressure drop over the support as well as likely concentration polarisation on the feed side resulting from the high flux. Membrane stability was also an issue at these conditions, however it was shown that stability could be improved by saturating the feed with silica. [ABSTRACT FROM AUTHOR]

Highlights: [•] Binderless NaX microsphere is prepared by chitosan-assisted hydrothermal synthesis. [•] Its surface area is 931m2/g and larger than those of the zeolite X powders. [•] Different adsorption properties for CO2 can be obtained by in-exchanging. [•] The microsphere exhibits quite high separation factor for CO2/N2 mixtures. [Copyright &y& Elsevier]

• V and Cr from V-Cr slag were separated using high-temperature heating without liquid contamination. • The reaction of Na 2 CO 3 with V-Cr slag results in the collection of volatile Na 2 CrO ' , NaCrO 2 , and other Cr compounds, achieving the separation. • The separation mechanism of V and Cr was clarified. A method to separate vanadium (V) and chromium (Cr) from vanadium-chromium (V-Cr) slag was developed to treat the hazardous substances effectively. This approach was achieved by heating V-Cr slag with Na 2 CO 3 in air within a temperature range of 30 °C to 1400 °C. Through TG-DSC, XRD, SEM-EDS and XPS tests, the results showed that Na 2 CO 3 reacted with V compounds at lower temperatures, producing NaVO 2 and Na 3 VO 4. At the high-temperature stage, Na 2 CO 3 reacted with Cr compounds, resulting in Na 2 CrO 4 and Cr 2 O 3 formation on the slag surface. As the temperature exceeded 1200 °C, volatiles (Na 2 CrO 4 , NaCrO 2 , and other Cr compounds) were generated from the residuals and collected by condensation to separate V and Cr. This method provides a novel strategy for eco-friendly resource utilization of V-Cr slag, which is highly efficient, minimizes hazardous wastes, and can be further promoted in the industry. [ABSTRACT FROM AUTHOR]

Schematic illustration showing the evolution of network structure for the cured and uncured PCS. • The microstructure of SiC-based ceramic could be precisely tailored via thermal-oxidative curing. • Either excessive or insufficient cross-linking could cause the micropores to collapse. • PCS membranes had high thermal stability and oxidation resistance at 500 °C. • The optimized PCS membrane had excellent gas permeation properties and displayed high performances for H 2 /C 3 H 8 separations. In this study, the physicochemical properties and microstructural variations of polycarbosilane (PCS) were systematically investigated at curing temperatures of 150–350 °C and pyrolysis temperatures of 350–850 °C. Oxidative cross-linking remarkably enhanced the thermal stability of the PCS structure. Elemental composition and microstructure of the final ceramic material could be precisely tailored via the air curing process. Cross-linking by air curing that is either excessive or insufficient could cause the micropores of the resulting ceramic material to collapse or disappear. The most promising PCS-derived membranes, which were cured at 250 °C and then pyrolyzed at 750 °C, had high thermal stability and oxidation resistance at 500 °C in addition to excellent permeation properties: H 2 permeance of 1–2 × 10−6 mol/(m2 s Pa) at 500 °C with H 2 /N 2 selectivity of 31 and H 2 /C 3 H 8 selectivity of 1,740; and, CO 2 permeance of 1.8 × 10−6 mol/(m2 s Pa) at 27 °C with CO 2 /CH 4 selectivity of 40. Moreover, permeance and selectivity in an equimolar H 2 /C 3 H 8 mixture at 500 °C were approximately the same as those in single gases, suggesting the separation mechanism could be ascribed to molecular sieving. This is the first study to propose the concept of tailoring the microstructure of SiC-based membranes by controlling the curing process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Downsizing a benchmark MOF into uniform nanosized materials. • Enhanced gas adsorption rate and capacity. • High-performance separation of propane and propylene. The separation of propane/propylene mixtures to produce polymer-grade propylene represents an important yet challenging task in the petrochemical industry. Metal-organic frameworks (MOFs) hold particular promise for the energy-efficient adsorptive separation of propane/propylene, in light of their structural diversity as well as highly tunable pore dimensions. MOFs exhibiting selective molecular exclusion for propylene over propane render exceptionally high adsorption selectivity. However, the relatively low adsorption capacity and/or slow diffusion kinetics have largely limited their separation efficiency. Here we report the fabrication of nano-sized crystals of a MOF-based splitter for propane and propylene. Compared to the micro-sized MOF samples, the nanocrystals display enhanced adsorption kinetics as well as notably improved adsorption capacity, making a new record with the highest efficiency for the separation of propane/propylene among all reported MOF-based splitters. Our study may shed light on the development of MOF-based adsorbents with optimal efficiency for industrially challenging gas separations. [ABSTRACT FROM AUTHOR]

• The large-scale synthesis of H 4 abtc (180 g scale) and Y-abtc (100 g scale) in high yields. • Breakthrough experiments on binary mixtures of propane/propylene at the 100 g scale. • Polymer grade propylene purity achieved using Y-abtc at 100 g scale. • Retained performance of Y-abtc at large scale demonstrating its potential for real world applications. Olefin/Paraffin separation, especially propylene purification from propane, is of extreme commercial importance as it produces chemical feedstock for synthetic plastics such as polypropylene. As an alternative to cryogenic distillation commonly used to purify these mixtures, the use of solid porous materials for adsorptive separation offers a more energetically efficient route. Metal-Organic Frameworks (MOFs) have shown great promise as adsorptive separation candidates in recent years. However, reports of these materials for the purification of C3 hydrocarbons exclusively provide insight of their performance in small scale laboratory settings. Single component isotherms and breakthrough curves are typically tested in the milligrams to gram scale. Herein, we present a scale-up, one-pot synthesis of a robust MOF with high propylene/propane selectivity. The organic linker 3,3′,5,5′-azobenzene-tetracarboxylic acid (H 4 abtc) and its yttrium-based MOF, Y-abtc, are both synthesized at the hundred-gram scale. Furthermore, we perform large-scale breakthrough experiments at the same scale. Our results show that Y-abtc samples synthesized from the one-pot 100 g scale reactions retain high crystallinity and size-exclusion based mechanism for the separation of propane/propylene mixtures. The same polymer-grade purity of propylene (>99.5%) is achieved as in the case of small scale (∼1 g) experiments. [ABSTRACT FROM AUTHOR]

[Display omitted] • C 2 H 4 /C 2 H 6 separation was studied using highly permeable ZIF-8 membranes. • The membrane temperatures were varied from −30 to 100 °C for separation. • A high C 2 H 4 permeance of 8.1 × 10−7 mol/(m2·s·Pa) was observed at −30 °C. Ethylene/ethane separation is a critical and energy-consuming process in the chemical industry due to the similar properties of the compounds and the great need of ethylene for e.g., polymer production. Many materials have been studied for their implementation as membranes as an energetically favorable alternative to conventional distillation and adsorption processes. Metal-organic frameworks (MOF) have revealed promising properties as highly permeable and selective membranes. Among the most studied and promising MOF candidates is ZIF-8, known for its thermal stability and small pores connected by narrow-sized windows. In this work, we present an analysis of the influence of parameters such as temperature, feed pressure and feed flowrate on the separation of ethylene/ethane through a thin ZIF-8/alumina disc membrane. We observed that the temperature has a significant effect on the separation. The ethylene permeance increased with decreased temperature and reached 8.1 × 10−7 mol/(m2·s·Pa) at −30 °C. At this temperature, the ethylene/ethane selectivity was 2.5. The study concluded with a considerable enhancement of the permeance of ZIF-8 membranes for ethylene/ethane separations, while maintaining a good selectivity compared to the reported values in the literature. The results have important implications for the development of more cost-effective and energy-efficient membrane-based separation technologies for ethylene purification. [ABSTRACT FROM AUTHOR]

[Display omitted] • A thin ceramic wafer was fabricated via an efficient phase inversion/sintering. • The thickness of the ceramic wafer was 250 μm with a mean pore size of 200 nm. • The high Al 2 O 3 loading helps their uniform distribution on membrane surface. • This wafer exhibited an ultrahigh and stable flux and oil removal efficiency. • The fouling analysis shows the dominant fouling mechanism was cake filtration. Efficient preparation of ceramic membranes helps to reduce costs and makes them more competitive in the field of wastewater treatment. In this work, an ultrathin Al 2 O 3 ceramic wafer membrane with a thickness of 250 µm and the mean pore size of approximately 200 nm was prepared from the Al 2 O 3 /polysulfone slurries via a casting-phase inversion/sintering approach. This ultrathin and hydrophilic ceramic wafer has a fully sponge-like and slightly asymmetric structure and desirable porosity, endowing it with an exceptionally high pure water permeability of ∼ 45,000 L m-2h−1 bar−1, an ultrahigh and stable emulsion flux of 2500 ∼ 3500 L m-2h−1 bar−1, as well as a high oil rejection of 99 % against real oilfield produced water (OPW). In addition, the increased Al 2 O 3 content enhanced the thermodynamic instability of the ceramic slurry, leading to the enhanced interfacial instability, which contributes to the uniform distribution of Al 2 O 3 particles on the precursor membrane surface to some extent during the phase inversion process, thus to reduce the surface defects of ceramic membranes after sintering. The membrane fouling analysis revealed that the dominant fouling mechanism was cake filtration, indicating the formation of a relatively dense and smooth skin layer of the ceramic wafer, which endow it with a high flux recovery ratio of 97.8 % by a simple chemical cleaning after OPW filtration. [ABSTRACT FROM AUTHOR]

[Display omitted] • A Z-scheme Ti-MOF/QDs/ZIS photocatalyst was fabricated. • The Ti-MOF/QDs/ZIS shows outstanding photocatalytic antibiotics degradation performance. • The Ti-MOF/QDs/ZIS exhibits excellent photocatalytic hydrogen evolution activity. • Ti-MOF/QDs/ZIS was very stable and easily recycled for reuse. • A possible mechanism for Ti-MOF/QDs/ZIS photocatalyst was proposed. Herein, a novel all-solid-state Z-scheme NH 2 -MIL-125(Ti)/Ti 3 C 2 MXene quantum dots/ZnIn 2 S 4 (Ti-MOF/QDs/ZIS) photocatalyst was prepared, then applied for photocatalytic antibiotic (tetracycline and sulfamethazine) degradation and hydrogen evolution under visible light. The Z-scheme Ti-MOF/QDs/ZIS photocatalyst afforded very efficient degradation of tetracycline (TC, 96% in 50 min) and sulfamethazine (SMZ, 98% in 40 min), as well as a high rate of hydrogen generation (2931.9 μmol g-1 h−1) under visible light irradiation. Trapping studies showed superoxide radicals (•O 2 −) to be the main active species for antibiotic degradation, with the intermediates formed during antibiotic photo-oxidation identified by liquid chromatography-mass spectrometry. Photocatalyst recycling studies showed the Z-scheme composite photocatalyst to be stable during both antibiotic photodegradation and hydrogen generation experiments. The Ti 3 C 2 MXene quantum dots facilitated electron transfer between the semiconducting components of Z-scheme composite photocatalyst. This work identifies a promising new Z-scheme photocatalyst system for water purification and solar hydrogen production. [ABSTRACT FROM AUTHOR]

[Display omitted] • MOF-11 breaks the trade-off between uptake and selectivity for Xe/Kr separation. • MOF-11 has the highest Xe uptake of 4.05 mmol/g at 0.2 bar and 298 K. • MOF-11 has high Xe/Kr Henry and IAST selectivity of 13.6 and 16.1 at 298 K. • Xe/Kr separation is achieved by the synergy between optimal pore size and OMSs. Efficient separation of Xenon (Xe) and krypton (Kr) is important in the gas industries but remains challenging. Adsorptive separation affords an energy-efficient method to isolate the two noble gases, yet developing selective adsorbents with high uptake and excellent selectivity remains difficult, limited by a trade-off between uptake and selectivity. We report MOF-11 with optimal pore size and accessible open metal sites (OMSs) for separation of Xe over Kr via the discriminable difference in van der Waals interactions. MOF-11 affords a new benchmark for Xe/Kr separation with high Xe uptakes of 4.05 and 4.95 mmol/g (at 0.2 and 1 bar), high Xe/Kr Henry and IAST selectivity (13.6 and 16.1) at 298 K. Evidenced by Xe-loaded structure, multiple Xe···H interactions between Xe and the terminal H atoms allow Xe atoms firmly packed within the framework. This work demonstrates a strategy for balancing uptake and selectivity in Xe/Kr separation by capitalizing on the synergy between optimal pore size and OMSs. [ABSTRACT FROM AUTHOR]

• A series of Z-scheme Ti-MOF/Ag/NiFeLDH photocatalysts were successfully fabricated. • Ti-MOF/Ag/NiFeLDH efficiently generated •O 2 − and •OH radicals under photoexcitation. • Aqueous Rhodamine B and Levofloxacin were rapidly degraded by Ti-MOF/Ag/NiFeLDH. • Ti-MOF/Ag/NiFeLDH was very stable and easily recycled for reuse. • Possible photocatalytic mechanism for Z-scheme Ti-MOF/Ag/NiFeLDH photocatalyst was proposed. Z-scheme hetero-structured photocatalysts show outstanding photocatalytic activity in many reactions. In this work, a series of novel Z-scheme photocatalysts were fabricated via the photo-reduction of plasmonic sliver nanoparticles on the surface of NH 2 -MIL-125 (Ti)/NiFe layered double hydroxide (Ti-MOF/NiFeLDH) hybrids. The obtained Ti-MOF/Ag/NiFeLDH composites showed excellent photocatalytic performance under visible light, with the Ag nanoparticles facilitating charge transfer across Ti-MOF/NiFeLDH heterojunctions, thus boosting the photocatalytic activity. At an optimized Ag loading, 95% of Rhodamine B (RhB) degradation was achieved within 50 min and 92% Levofloxacin (LVX) degradation within 70 min. The degradation intermediates of LVX were analyzed by LC-MS and the decomposition pathways were proposed. Further, the Z-scheme Ti-MOF/Ag/NiFeLDH photocatalyst demonstrated outstanding reusability and stability in recycling tests (removal efficiencies of 92% for RhB and 90% for LVX after 5 successive test cycles). Trapping experiments revealed that superoxide radicals (•O 2 −) and hydroxyl radicals (•OH) were two main reactive species formed under visible light, with valence holes (h+) playing a minor role. Results allowed the mechanisms for antibiotic (i.e. LVX) and dye degradation over Ti-MOF/Ag/NiFeLDH to be proposed. This study introduces a new strategy, the combination of MOFs, LDHs and plasmonic Ag nanoparticles, for fabrication of high-performance Z-scheme photocatalysts for the removal of water pollutants. [ABSTRACT FROM AUTHOR]