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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] • 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]