In-Hyuck Song

Asymmetric SiC membranes with surface pore sizes ranging from 0.12 to 0.31 μm at a constant open porosity of approximately 42% were fabricated by dip-coating SiC support followed by sintering from 1700 to 2000 °C. The effect of membrane structural constants (hydraulic resistance (k₁), pore size exponent (k₂), and shape factor (k₃)) on PWP were evaluated by comparing the symmetric and asymmetric structures. In addition, the experimentally determined values of PWP were quantitatively analyzed by comparing with theoretically predicted values obtained using the Kozeny–Carman (K–C) and Hagen–Poiseuille (H–P) models. Despite having a smaller pore size, the asymmetric membranes exhibited high PWP (1257-3883 LMH) due to decreased flow resistance (low k₁), enhanced pore size effect (high k₂), and improved flow network (high k₃) as compared to symmetric membranes. The hydrophilicity of the prepared membranes improved remarkably, with increasing average surface roughness (102.3 nm to 161.0 nm) due to an increase in pore size, which also caused a decrease in water contact angle (WCA) from approximately 27.44° to 21.67° with increasing sintering temperature (1700–2000 °C). Furthermore, the prepared membrane separation performance was found to be affected by its pore size, and the 1900 °C sintered SiC membrane showed optimal gradient profile and pore structure, demonstrating its practical reusability and scalability for O/W wastewater treatment.

This study aims to compare the carbon footprints associated with the fabrication of two types of alumina-based tubular ceramic membranes used in microfiltration (MF): a multichannel membrane produced by extrusion and dip-coating, and an asymmetric hollow fiber membrane fabricated via phase inversion. The multichannel process involves two sintering steps but uses no organic solvents, whereas the phase-inversion method simplifies production through single-step shaping and sintering but requires organic solvents that increase environmental burdens. Using a functional unit of 1 m² effective membrane area, carbon emissions were quantified from raw material extraction to waste disposal. The results showed total emissions of 8.57 kg CO₂-eq/m² for the multichannel membrane and 10.67 kg CO₂-eq/m² for the hollow fiber membrane. Although the hollow fiber process consumed less energy, its extensive use of solvents, particularly NMP, led to significantly higher emissions. This study provides the first quantitative comparison of these two common ceramic membrane fabrication routes and underscores the importance of considering both energy use and solvent impacts when evaluating the environmental sustainability of membrane production. A sensitivity analysis further evaluated the influence of key parameters, including alumina emission factor, regional electricity carbon intensity, alumina recycling, and solvent substitution or NMP recycling. The analysis demonstrated that each factor could significantly influence the total carbon footprint and, under favorable conditions, narrow or even reverse the gap between the two fabrication routes. This study provides the first quantitative comparison of these two common ceramic membrane fabrication methods and highlights the importance of considering energy use, solvent impacts, and potential mitigation strategies when assessing the environmental sustainability of ceramic membrane production.

Objective: Mongolia has few freshwater resources. It is therefore important to conserve water resources. An efficient possibility is to purify water and reuse it. Therefore, the scientists from the Material Science Center of the Mongolian University of Science and Technology collaborated with the researcher from the Korea Institute of Material Science and carried out a project between 2017-2020. Theoretical Framework: In this study, Mongolian zeolites and prepared kaolin were used and flat tubular porous support was extruded by a double screw vacuum extruder at KIMS. Method: The supports were burned at 800 and 1000°C and the properties such as pore distribution were determined by mercury porosimetry Results and Discussion: The zeolite-kaolin support had a bulk density of 1.46 g/cm3, a porosity of 41.52% and, an average pore size of 218 nm. With its water permeability of 115 L/m2·h at 0.01 MPa and 970 L/m2·h at 0.08 MPa, the support achieved good results. Research Implications: The wastewater treatment tests show that these membranes also have good compressive strengths. We have cleaned the sewage from a leather factory, which was very highly contaminated and has high viscosity. Originality/Value: Since there is no chemical industry in Mongolia, raw materials for synthetic materials are imported. The main significance of this research work lies in determining the possibility of producing ceramic membranes for water filtration using the mineral resources of our country, and it will serve as the basis for future research.

The proper application of millimeter-sized spherical porous ceramic supports in catalytic operations relies on their ease of handling, convenient separation, recyclability, high-catalyst-solid loading, and the optimum mass transfer of reactants and products. However, common granulation techniques of spherical carriers entail complex liquid-phase-based processes under severe conditions and the use of toxic or expensive reagents. The present study discusses the manufacturing of porous ceramic granules derived from an inexpensive silica source (diatomite, solid network) and a biopolymer cross-linked by ion exchange (sodium alginate, patterning structure). The results indicated that, with fixed granulation conditions, porous diatomite granules with a sphericity of approximately 0.9 could be successfully obtained by optimization of the diatomite/sodium alginate dispersion to a 30.07 wt.% solid content and 1560 mPa·s viscosity (at ~0.3 s⁻¹). Moreover, the described manufacturing process was proven effective in developing hierarchically porous diatomite granules that were heat-treated at 1200 °C with high sphericity (~0.9), acceptable compressive strength (5.17 ± 0.31 MPa), and porosity features (total porosity: 69.0 ± 2.9%, macropore size: 2.777 μm, mesopore size: 35.34 nm), establishing them as well-matched support materials for either catalytic or adsorption applications.

The influence of various transition metal (Mo, Co, Ni, and Fe) additives on the electrical and mechanical properties of mullite‐strengthened SiC sintered in the range of 1100–1500°C under an Ar atmosphere was investigated. Kaolin was added as a low‐temperature sintering aid in the designed formulations. The addition of metal additives reduced the electrical resistivity, enhanced the mechanical strength, and produced samples with an approximately 40% porosity. The decrease in electrical resistivity was attributed to the in situ formation of electrically conductive metal silicides, whereas the conversion of kaolin to mullite enhanced the mechanical properties. The comparative study shows that at the same metal‐additive content (15 wt%), Fe was the most effective element to reduce the electrical resistivity and increase the flexural strength, which were recorded as 8.0 × 10⁰ Ω cm and 20 ± 2 MPa, respectively, of the samples sintered at merely 1300°C.

We introduced a modified sol-gel method using polyvinyl alcohol (PVA) as an additive to improve the permeability of γ-Al₂O₃ membranes by minimizing the thickness of the selective layer and maximizing the porosity. First, the analysis revealed that the thickness of γ-Al₂O₃ decreased as the concentration of PVA increased in the boehmite sol. Second, the properties of the γ-Al₂O₃ mesoporous membranes were greatly influenced by the modified route (method B) compared to the conventional route (method A). The results showed that the porosity and surface area of the γ-Al₂O₃ membrane increased, and the tortuosity decreased considerably using method B. This effect was attributed to the adsorption of PVA molecules on the surface of the boehmite particles, which depended on the synthesis route. The experimentally determined pure water permeability trend and the Hagen–Poiseuille mathematical model confirmed that the modified method improved the performance of the γ-Al₂O₃ membrane. Finally, the γ-Al₂O₃ membrane fabricated via a modified sol-gel method with a pore size of 2.7 nm (MWCO = 5300 Da) exhibited a pure water permeability of over 18 LMH/bar, which is three times higher than that of the γ-Al₂O₃ membrane prepared using the conventional method.