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Porous materials with wrinkled surfaces could have broad applications in catalysis and adsorption. However, designing cellular ceramics with similar structures is challenging. Herein, we demonstrated the binary colloidal self-assembly of γ-Al 2 O 3 nanoparticle/silica gelation network for constructing such materials. The competitive effect between volume shrinkage and surface bend during water evaporation of silica gel contributed to wrinkled aperture surface. During calcination, silica nanoparticles were highly active to react with alumina to form mullite nanocrystals, bringing about high compressive strength at low relative densities. After calcining at 1350 °C, resultant products with hierarchical structure exhibited an outstanding compressive strength of 4.2 MPa, a relatively high surface area of 7.23 m2/g at a porosity level of 83.3%. The current strategy provides a feasible and affordable approach for producing high performance ceramic foams towards practical application fields in catalysis and adsorption. [ABSTRACT FROM AUTHOR]

Aryl‐aryl linked two‐dimensional covalent organic frameworks (2D‐COFs) were synthesized by interfacial trimerization of 4,4′‐diacetylbiphenyl. The 2D‐COFs presented rigid skeleton structure, regular porosity and micron‐scale layered nanosheet structure, which can be easily exfoliated by sonication without destroying the micron size. The integration of 2D‐COFs and cellulose matrix via non‐solvent‐induced phase separation has facilely generated 2D‐COFs/cellulose composite monolith with hierarchical structure bearing nano/micro scale pores and 2D/3D dimensions. The composite monolith material has been successfully applied to dye adsorption using methylene blue (MB) and rhodamine B (RhB) as model adsorbates under aqueous conditions. At an initial dye concentration of 200 mg L−1 and neutral pH conditions, excellent adsorption capacities were presented (91.5 mg g−1 for MB, 67.3 mg g−1 for RhB), with satisfactory recyclability and good compatibility to different dye concentrations and pH environment. We anticipate the techniques will broaden the fabrication of COFs and related composite materials, and enable promising practical applications in porous materials and waste water treatment. [ABSTRACT FROM AUTHOR]

• Fractal polyhedral MOFs (Cu-TATB) is synthesized for CO 2 /N 2 separation. • Small-sized pores can capture CO 2 , while large-sized pores facilitate N 2 escape. • Different sized channels successfully achieving the goal of gas separation. A fractal polyhedral pore structural MOFs (Cu-TATB) is synthesized from the coordination of tridentate ligands (H 3 TATB) and Cu 4 clusters. This material is characterized by single crystal X-ray diffraction, powder X-ray diffraction, thermogravimetric analysis. The structure contains two different pore structures, including closed octahedral cages and open tetrakaidecahedron cages. The material has been successfully utilized for the separation of CO 2 /N 2 due to the fractal structure of the channel with different pore sizes. Under optimized temperature, Cu-TATB adsorbed a large amount of CO 2 and only negligible amount of N 2 , and the selectivity reaches 27. Breakthrough experiments demonstrated that this material can efficiently separate N 2 and CO 2. This structure further demonstrates the infinite potential of 3D MOFs with diverse pore structures in applications such as CO 2 adsorption and separation. [ABSTRACT FROM AUTHOR]

Gas-in-liquid foam templating is considered as a promising method for commercial-scale production of porous materials. However, Ostwald ripening occurs frequently during the preparation, which could bring about inhomogeneous bubbles with large sizes and deteriorate the performance of resultant products. To tackle this challenging task, we report a gelation network-triggered morphology-regulation strategy during the foaming process. As an exemplar, boehmite sol was incorporated into the andalusite suspension to stabilize the foam framework. After casting, the wet foam was able to maintain its overall shape, since andalusite particles were anchored onto the gas-liquid interface by the gelation network during mechanical frothing. The samples calcined at 1400°C feature homogeneous bubble with hierarchical porous architecture, smaller pore size with a mean value of 5.32 μm and robust compressive strength of 11.97MPa at a porosity level of 84 %. Our approach substantially broadens the design philosophy of high performance porous ceramics. [ABSTRACT FROM AUTHOR]

In this study, novel porous LaPO 4 ceramics possessing closed spherical pores and thin pore walls have been firstly synthesized using the particle-stabilized foaming method. Affected by the calcination temperature together with solid loading, the obtained porous LaPO 4 ceramics exhibit high porosity (81.69–94.21 %), very low thermal conductivity (κ) (0.124–0.398 W m−1 K−1) and relatively high compressive strength (0.886–9.30 MPa). When the calcination temperature and solid loading are 1500 °C and 35 wt%, optimized porous LaPO 4 ceramics achieve a better balance between thermal conductivity (0.160 W m−1 K−1) and compressive strength (2.07 MPa). Based on this, the prediction model for the thermal conductivity is screened and the thermal insulating capability is further verified. This work suggests that porous LaPO 4 ceramics have the potential to be applied as thermal insulation material in the future. [ABSTRACT FROM AUTHOR]

In this work, the PVDF/glass as-prepared composite membrane was prepared through phase-inversion method and used to adsorb methylene blue dye. The results of SEM and BET showed that the membrane had an asymmetric nanoscale porous structure. The electronegativity on the surface of membrane was determined through zeta potential test. The adsorption properties of as-prepared composite membrane and glass membrane were studied through testing the removal ratio of methylene blue from aqueous solution. Then the effects of membranes dose, pH value, temperature and initial concentration on the removal ratio were systematically studied. The adsorption mechanism was also studied. The adsorption kinetics and adsorption isotherm fitted well with the pseudo-second-order model and Freundlich model, respectively. In addition, the adsorption efficiency of glass membrane basically remained 85% after eight repeated adsorption-calcination cycles. The obtained membranes could be reused for methylene blue removal with high efficiency for multiply times. [ABSTRACT FROM AUTHOR]

Hierarchical structured porous ceramics have attracted tremendous research interests because of their numerous excellent properties including robust mechanical strength and large surface area. In this work, silicon carbide (SiC)‐based porous ceramics with three levels of pore hierarchy are fabricated from silicon particle‐stabilized foams and a subsequent one‐step calcination after they were embedded with coke. Three‐dimensional (3D) flexible nanofibrous network is adhered and wrapped on cell walls of porous ceramics, which is readily fine‐tuned and tailored by the temperature to provide optimized pore structure. The resultant SiC‐based porous ceramics present a density of 1.03 g/cm3 at a porosity of 72% with a large quantity of hierarchical micro‐ and macropores. This hierarchical structure leads to robust compressive strength (23.52 MPa) and large surface area (64.32 m2/g). The fabrication method is straightforward and sought‐after, providing a facile technical route for advanced hierarchical porous ceramics used in filtration and catalysis fields. [ABSTRACT FROM AUTHOR]

Herein, the advantage of single-shell hollow microspheres on forming pores has been exploited to acquire porous ceramics with homogeneous microstructure, while the hollow microspheres also acted as reaction source. Dispersant reaction method has been applied to realize the perfect combination between microspheres and Si3N4 particles, which could be attributed to the repulsion between particles is weakened, particles agglomerate together and holding microspheres among them tightly. Owing to the normal distribution of hollow spheres and their single-shell structure, porous Si2N2O-Si3N4 ceramics with uniform pore distribution have been fabricated. The results show that the addition of silica hollow spheres contributes to the decrease in dielectric constant, since their porosity could be increased effectively and Si2N2O phase exhibiting low dielectric constant is generated. High-performance porous Si3N4 ceramics with porosity of 45.7% have been prepared through employing fly ash hollow microspheres, which possess flexural strength of 108.76 ± 6.25 MPa, fracture toughness of 1.78 ± 0.09 MPa m1/2 and dielectric constant of 3.53. This strategy is proved to be a convenient, eco-friendly and effective method to synthesize ideal candidates for radomes. [ABSTRACT FROM AUTHOR]

Abstract: A novel porous coal gangue microsphere/geopolymer (CG/KGP) composite was firstly synthesized by adding gangue microspheres into geopolymer matrix. Effects of precalcined temperature of CG microspheres on the microstructure and specific surface area of the porous CG/KGP particles were systematically investigated. Adsorption properties of the CG/KGP composites were also reported. Results showed that the CG/KGP composites contained mainly amorphous phase and many functional groups were on the particle surface. The precalcined CG microspheres were dispersed homogenously and bonded well with the KGP matrix. The CG900/KGP samples showed better adsorption properties than the pure KGP. As for the dosage of 4 g/L (starting concentration, 100 mg/L), adsorption capacity achieved the highest value of 24.6 mg/g and the removal efficiency reached 98%. Adsorption of MB onto CG900/KGP particles followed the pseudo‐second‐order kinetic model. The novel porous CG/KGP composite has potential application in wastewater filtration and adsorption treatment. [ABSTRACT FROM AUTHOR]

An innovative approach for fabricating porous alumina ceramics (PACs) with improved mechanical and thermal properties using walnut shell powders as pore-forming agent combined with alumina sol impregnation is reported in the present work. It is demonstrated that uniform distribution of spherical pores can be observed in as-prepared PACs by using above technical route. The decrease of walnut shell powder sizes significantly promotes the enhancement of crushing strength and reduction of thermal conductivity of the PACs. Meanwhile, the impregnated alumina sol is favoring for the formation of spherical micro-pores, then further improves their mechanical and thermal insulation performances. The lowest thermal conductivity and highest crushing strength of resulting sample reach 0.16 W/m K and 29.2 MPa, respectively. This novel method offers new possibilities to fabricate high-quality PACs. [ABSTRACT FROM AUTHOR]

Abstract: In order to investigate the relationship between pore structure and thermal conductivity as well as mechanical strength, porous alumina ceramics (PAC) with various pore structures were fabricated, using starch as the pore‐forming agent. Fractal theory was employed to characterize the pore size distribution more accurately than ever used parameters. The results show that the increase in starch content in PAC leads to an enhanced porosity, a higher mean pore size, and reduced fracture dimension, thermal conductivity and strength. The fractal analysis indicated that the fractal dimension decreases gradually and reaches its minimum value with increasing the starch content up to 25 wt%, but the further incorporation results in an opposite trend. It is suggested from micro‐pore fractographic analysis that the optimization of both thermal insulation performance and mechanical strength are positively correlated with the increase in the mean pore size and proportion of 2‐14 μm pores but negatively corrected with the porosity. These results provide a new perspective and a deeper understanding for fabrication of PAC with both excellent thermal insulation and mechanical performance. [ABSTRACT FROM AUTHOR]

Abstract: A novel method for fabrication of highly porous barium strontium titanate (BST) ceramic foams based on particle‐stabilized foaming method was developed for the first time, in which propyl gallate (PG) was employed as BST particle modifier. The results showed that the stability of wet BST foams closely depends on the pH value and PG concentration, which could be explained by the adsorption behavior of PG on BST particle surface. BST ceramic foams with dense, uniform, and closed pore and defect‐free wall were obtained. The pore size and porosity can be well controlled by adjusting solid loading and sintering temperature. It was revealed that not only sintering temperature but also solid loading significantly influenced the growth of BST grain. The BST ceramic foams exhibited high porosity in the range of 81%‐95%, low dielectric constant in the range of 47‐150, and low dielectric loss below 0.0025. The BST ceramic foams with higher porosity presented a tendency of lower dielectric constant and the fitting results indicated that the natural logarithm of dielectric constant was linear correlated with porosity. [ABSTRACT FROM AUTHOR]

Ginsenosides have been widely conceded as having various biological activities and are considered to be the active ingredient of ginseng. Nowadays, preparative high-performance liquid chromatography is considered to be a highly efficient method for ginseng saponins purification and preparation. However, in the process of practical application, due to the complex and varied composition of natural products and relatively simple pretreatment process, it is likely to block the chromatographic column and affect the separation efficiency and its service life. In this work, an orthogonal strategy was developed; in the first-dimension separation, reverse-phase macroporous resin was applied to remove impurities in ginseng crude extracts and classified ginseng extracts into protopanaxatriol and protopanaxadiol fractions. In the second-dimension separation, the obtained fractions were further separated by a preparative hydrophilic column, and finally yielded 11 pure compounds. Eight of them identified as ginsenoside Rh1, Rg2, Rd, Rc, Rb2, Rb1, Rg1, and Re by standards comparison and electrospray ionization mass spectrometry. The purity of these ginsenosides was assessed by high-performance liquid chromatography with UV detection. [ABSTRACT FROM AUTHOR]

In the present work, carbon black (CB) works as a pore-forming agent in the preparation of alumina porous ceramics. The pore structures ( i.e. mean pore size, pore size distribution and various pores size proportions) were characterized by means of Micro-image Analysis and Process System (MIAPS) software and mercury intrusion porosimetry. Then their correlation and thermal conductivity as well as strength were determined using grey relation theory. The results showed that the porosity and mean pore size increased against the amount of CB, whereas the thermal conductivity, cold crushing strength and cold modulus of rupture reduced. The <2 μm pores were helpful for enhancing the strength and decreasing the thermal conductivity whereas the >14 μm pores had the opposite effects. [ABSTRACT FROM AUTHOR]

• Graphene oxide (GO) film with asymmetric surface structure was self-assembled. • The GO film was flame-expanded and exfoliated into porous graphene film (PGF). • The PGF shows ultrahigh adsorption rates for organics. Porous graphene film (PGF) with unique surface consisting mostly of thermal-exfoliated worm-like graphene sheets were fabricated through flame expansion-exfoliation of graphene oxide film with non-exfoliated graphite oxide powders precipitated at its bottom. The resultant PGF showed not only faster adsorption rate during oil/solvent collection in comparison with traditional PGFs, but also similar high adsorption capacity and reliable recyclability. For instance, the adsorption capacities of the new PGF for organic solvents were in the range of ~11–33 times of its own weight, and they displayed good stability during ten exchange-evaporation recycling process. Moreover, this approach can be easily scalable and applied to prepare other PGF composites. [ABSTRACT FROM AUTHOR]

The present work studied a simple direct foaming method for preparation of porous alumina ceramics by expansion of a ceramic suspension based on polyurethane (PU) foam system. The effects of polyurethane formulas including catalyst composition, blowing agent content, NCO index and solid content on the samples properties were investigated. The results showed that the homogeneity, porosity and mechanical properties are various for different formulas. The dried green bodies showed diametrical compressive strength in the range of 0.39-1.25 MPa and were amenable to machining operations such as milling, drilling and lathing. Meanwhile, PU formulas play an important role in the microstructures and mechanical properties of green bodies and sintered ceramic foams. Pyrolytic removal of polyurethane skeleton followed by sintering at 1550 °C produced alumina bodies with open cell porosity 54-75% and diametrical compressive strength 1.39-28.47 MPa. Microstructure showed both large (200-300 μm) and small (50-100 μm) pores all with various sizes of windows. Based on the optimization of polyurethane formulation, the porous alumina foam with porosity of 64% and compressive strength of 25.26 MPa was prepared. This polyurethane foam system is easily available and low-cost, which could be widely applied in preparation of other porous ceramics, such as ZrO2, SiO2, etc. [ABSTRACT FROM AUTHOR]

We herein report a novel hierarchically porous ceramic foams derived from boehmite gel foams, which possess both high porosity and superior strength. The gel foams show excellent printability due to its predominant stability, high yield stress and storage modulus, which endows such foam material ideal ink for 3D printing lightweight and complex-shape materials via direct ink writing approach. The 3D printed ceramic foams possess programmable architecture assembled by porous filaments, uniform macro-pores with tunable size in the range of 4∼70 μm, as well as nanoscale pores in cell wall, after sintering at relatively low temperature of 1200–1300 °C. In this way, ceramic foams with high strength were achieved, attributed to the tiny grains, large amount of grain boundaries, uniform pores and hierarchical pore structure. Notably, the foams sintered below 1200 °C have significant advantage on specific surface area, which could reach up to 300-400 m2/g. [ABSTRACT FROM AUTHOR]

Abstract In the present work, Al 2 O 3 -Si 3 N 4 porous ceramics with a cactus-like architecture were fabricated by calcining Al 2 O 3 -Si binary particle-stabilized foams in the nitrogen atmosphere. A large number of acicular Si 3 N 4 nanobelts were constructed on the surface of cell walls as a consequence of CVD process to achieve an interlaced network. Such structure was beneficial to realize a high capture efficiency of particulate matters (PM) during filtration. Resultant products having a bulk density of 0.38 g/cm3 at an apparent porosity of 86% can potentially be applied as the air filters in environment field. [ABSTRACT FROM AUTHOR]

Compressive strength is one of the most important mechanical properties for ceramic foams but the dependence of compressive strength of highly porous ceramic foams on porosity remains unclear up to now, especially for the ceramic foams with porosity above 94%. In this paper, the relationship between compressive strength and porosity of ceramic foams with high porosity in the range of 79–98% was studied for the first time. The alumina ceramic foams and zirconia foams were prepared by particle-stabilized foaming method using sodium dodecyl sulfonate (SDS) as foaming agent. It was found that the function relation between compressive strength and porosity depended on porosity level. Specifically, compressive strength of ceramic foams fitted well with Rice Model when the porosity ranged from 79% to 94%. When the porosity increased above 95%, compressive strength of ceramic foams showed linear relation to porosity, which was probably due to the characteristic of highly porous ceramic foams with thin and lamellate cell wall. [ABSTRACT FROM AUTHOR]

• A novel type of aryl-triazine linked two-dimensional covalent organic frameworks (2D-COFs). • 4-Acetylbenzonitrile as a "two-in-one" type monomer for trimerization toward COFs. • A simple, efficient, scalable synthetic approach toward 2D-COFs. • Efficient adsorption for phenolic compounds. • DFT calculations support improved adsorption with the triazine-incorporated 2D-COFs. We report the synthesis of aryl-triazine linked two-dimensional covalent organic frameworks (2D-COFs) via trifluoromethanesulfonic acid-catalyzed trimerization, employing 4-acetylbenzonitrile as a "two-in-one" type monomer in COFs synthesis for the first time. It enables the simple and scalable synthesis of COFs with outstanding thermal stability and lamellar structure at >90 % yield via convenient operations. 2D-COFs have been applied for the adsorption of phenol, bisphenol A and 1-naphthol, exhibiting a pseudo-second-order kinetics. Calculations demonstrated that the incorporation of triazines into aromatic 2D-COFs benefit the adsorption process. The facile synthesis and aryl-triazine-linked architecture should broaden opportunities toward more 2D-COFs and facilitate potential applications. [ABSTRACT FROM AUTHOR]

• A flow-through Ti/TiO 2 -NTA/Ti 4 O 7 was modified by TiO 2 nanotube array. • The flow-through mode is significantly superior to the traditional flow-by mode. • Favipiravir removal ratio was as high as 93.4% at Ti/TiO 2 -NTA/Ti 4 O 7 anode. • A high removal ratio of 87.7% for favipiravir can be achieved in actual wastewater. In this study, TiO 2 nanotube arrays (TiO 2 -NTA) were used as an intermediate layer to provide effective electrocatalytic activity and stability for Ti/TiO 2 -NTA/Ti 4 O 7 anode. Compared with Ti/Ti 4 O 7 anode, Ti/TiO 2 -NTA/Ti 4 O 7 anode exhibited higher oxygen evolution potential (2.40 V), larger active specific surface areas (1.81 m2 g−1), stronger radical generation capacity (64.42 μM), longer accelerated service life (56.0 h), and superior favipiravir removal ratio. The flow-through electrochemical reaction system was constructed by using the porous Ti/TiO 2 -NTA/Ti 4 O 7 anode. The removal ratio, TOC removal ratio and mineralization current efficiency of favipiravir in the flow-by electrochemical system were significantly improved and the energy consumption was reduced compared with the conventional flow-by electrochemical system, verifying the superiority of the porous flow-through Ti/TiO 2 -NTA/Ti 4 O 7 anode. The effects of operating parameters on the removal of favipiravir in the flow-through electrochemical reaction system were investigated. The degradation mechanisms of favipiravir are the synergetic effects of the free radical (·OH and SO 4 −·) and the direct electron transfer. Ti/TiO 2 -NTA/Ti 4 O 7 anode displayed excellent stability in five consecutive cycles, exhibited significant removal ratio (87.7%) of favipiravir from actual wastewater, and remained efficient and versatile for a wide range of typical PPCPs pollutants. Therefore, Ti/TiO 2 -NTA/Ti 4 O 7 is a promising porous anode material in the engineering application. [Display omitted] [ABSTRACT FROM AUTHOR]

• A novel type of aryl-aryl linked two-dimensional covalent organic frameworks (2D-COFs). • An efficient, scalable, mild and interfacial synthetic method toward 2D-COFs. • 2D-COFs featured with layered nanosheet structure of large surface area, aryl-aryl linked backbone, dispersible in organic solvent. • Efficient adsorption for polycyclic aromatic hydrocarbons. A novel type of aryl-aryl linked two-dimensional covalent organic frameworks (2D-COFs) material possessing layered nanosheet structure with a large surface and regular porosity was constructed via trimerization of acetyl at the dynamic interface of dichloromethane and trifluoromethanesulfonic acid. This synthetic strategy compared with traditional COFs synthetic methods has the advantages of simple condition, low temperature, short reaction time, high yield, and absence of a metal catalyst. Due to the strong π–π interaction and hydrophobic effect, associated with high surface area and highly ordered 2D open nanopores, 2D-COFs have been successfully applied to the adsorption of toxic organic compounds of polycyclic aromatic hydrocarbons (PAHs). [ABSTRACT FROM AUTHOR]

Fibrous materials, such as cellulose papers, fibres, or textiles, are regarded as potential evaporation materials used in evaporative cooling systems. The fibrous material's wettability and evaporation characteristic have significant influences on heat and mass transfer performance of evaporative cooling systems. This paper studied the wicking performance of selected fibrous materials including cellulose/PET fibre, Coolmax fabric and wood pulp paper by numerical modelling and dedicated experiment based on transient weight and optical measurements. The effect of evaporation on the performance of wicking rise were analysed in depth using the obtained experimental data. The measured data show good agreements with the predicted results, within ± 6.67%, 7.47% and 3.78% errors for the three types of materials, respectively. The microstructure parameters that control water diffusion performance of porous materials, i.e., permeability to effective pore radius ratio, were found to be highest for cellulose/PET fibre followed by Coolmax. Additionally, the study compared water evaporation rate of the selected materials by a few validated preliminary tests operating under various ambient air velocities and surface temperatures. Coolmax and cellulose/PET fibres were found to have similar higher evaporation rate than wood pulp paper. This paper presented numerical and experimental approaches for accurately characterising and differentiating wicking and evaporation performance of fibrous materials which would contribute to optimise evaporation materials for evaporative cooling systems. [ABSTRACT FROM AUTHOR]