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Designing high-performance ceramic adsorbent with a wide spectrum of properties such as regulatable pore structure, high surface area, ultrahigh organic dye removal efficiency and renewability in an affordable and rational approach is vital for real-life applications. However, integrating all these individual functionalities simultaneously into one bulky material is still challenging. Herein, hierarchical porous ceramic adsorbents with nanofibrous-granular composite structure were proposed via colloidal co-assembly of coal-containing kaolin waste and silicon to resolve the above conflicting demands. Such structure endows the resultant products with satisfactory surface area of 52 m2 g−1, ultrahigh malachite green removal efficiency of 97.6%, outstanding adsorption capacity of 97.6 mg/g, excellent renewability after calcining at 500 °C. Such ceramic adsorbent provides a sustainable and feasible strategy for fabricating water purification materials. [ABSTRACT FROM AUTHOR]

The design and synthesis of new filtration materials for high-temperature particulate matter capture are of both technological and scientific importance but still remain a challenging task. In the current work, we presented an approach for the manufacturing of highly porous SiC cellular ceramics by combining polyether polyol-modified carbon black with polyurethane foaming method. Hydroxyl groups were introduced to the surface of carbon black to prevent agglomeration. As-obtained SiC cellular ceramic possed three-dimensional interconnected reticular architecture with the abundant micron-sized window on its cell wall. The resulting porous SiC ceramic exhibited a high removal efficiency (95.8%) with extremely low pressure drop (38 Pa). The successful fabrication of such fascinating material may provide new insights for high-temperature particulate matter filtration. [ABSTRACT FROM AUTHOR]

Engineering high performance cellular ceramics with both ultralow density and satisfactory compressive strength for practical applications still represents a grand challenge. Herein, alumina-based cellular ceramics bonded by in-situ formed mullite phase were constructed by Al 2 O 3 –Si-boehmite particle-stabilized foams. The gelation of boehmite sol improved the stability and harnessed the deformation of dried Al 2 O 3 –Si composite foam. The oxidation of silicon and further generation of in-situ mullite phase enhanced the chemical bond between alumina particles on cell walls, resulting in the superior mechanical properties. As an exemplar, the resulting cellular ceramic possessed the robust compressive strength of 2.26 MPa at a high porosity of 87.8%. The gelation-assisted Al 2 O 3 –Si particle-stabilized foams provide a facile and convenient strategy for construction of composite ceramic foams with high porosity and robust strength. [ABSTRACT FROM AUTHOR]

Cellular ceramics with 3D network architecture are attracting ever-increasing attention because of their great application potential in multiple fields. Unfortunately, a daunting challenge still remains for fabricating such materials. A novel methodology is provided in the current work to construct cellular ZrO 2 ceramics with such architecture by combining polyurethane foaming and chemical modification technology. Stearic acid grafted ZrO 2 powder with improved dispersibility allows the successful assembly into the polyurethane porous framework. The obtained cellular materials possess a three-dimensional network architecture with windows on the cell wall. The resulting ZrO 2 cellular ceramic with such unique structure exhibits a relatively high porosity (83.5%) and robust compressive strength (13.5 MPa), which outperforms most of the existing ZrO 2 -based counterparts. With above advantages, we envision that as-prepared products are promising for filter applications. [ABSTRACT FROM AUTHOR]

Ultralight ceramics with striking mechanical properties and improved pore connectivity could have wide applications in areas ranging from catalyst support to hot gas filtration. However, creating such materials has proven to be a challenging target. This work demonstrated a novel methodology to prepare porous MgAl 2 O 4 ceramics by calcining gelled MgO–Al 2 O 3 –SiO 2 particle-stabilized foams. The striking green strength of dried foams can be achieved as a consequence of MgO hydration and subsequent formation of gelled Mg(OH) 2 and MgO–SiO 2 –H 2 O skeleton. The decomposition of colloidal substance at elevated temperature resulted in the formation of small pores on the cell wall, thus forming the hierarchical porous architecture and improving the pore connectivity. The highly porous MgAl 2 O 4 ceramics fired at 1600°C possessed the integrated properties of ultrahigh porosity (87.0%), improved pore connectivity and satisfactory compressive strength (7.93 MPa), showing great potential to be used in multiple industrial fields. [ABSTRACT FROM AUTHOR]

Abstract A facile method for preparation of SiC nanofibrous network reinforced hierarchical structured porous Si 3 N 4 based ceramics via annealing Si-Si 3 N 4 binary particle-stabilized foam in coke bed is reported in this work for the first time. The atmosphere created by coke bed enables the fabrication of Si 3 N 4 based porous ceramics at 1450 °C without using sintering additives. As prepared specimens possess a relative high compressive strength due to the partial oxidation of Si 3 N 4 particles. This novel structure with three levels of hierarchy characterized by flexible SiC nanofibrous network, cell walls and unit cells can be characterized. The vaporization of silicon powder results in formation of Si(g), SiO(g) and allows subsequent generation of SiC nanofibrous network, leading to a considerable number of micro-pores on cell walls simultaneously. As-prepared porous ceramics contained 76.7% porosity and had compressive strength of 10.81 MPa. [ABSTRACT FROM AUTHOR]

Constructing high-performance air filters for high-temperature particulate matter (PM) removal is of great importance but remains challenging. Here we demonstrate the ceramic foam-based filters via polyurethane (PU) foaming using diatomite and kaolin powder as the starting materials. Diatomite was grafted by dodecanedioic acid (DA) to improve the dispersity in the PU slurry. The calcined products demonstrated a hierarchical pore structure with multiple well-controlled micron-sized window pores on the cell wall of the sub-micron bubble. The resulting products exhibited a high removal efficiency (96.3%) at a pressure drop of 33 Pa. This research showed that as-prepared ceramic foams can be potentially used as new high-temperature filters for high-temperature PM removal. [ABSTRACT FROM AUTHOR]

The generation of PVA hydrogel through freeze-thaw technique has been utilized innovatively to complete the forming process of porous Si 3 N 4 ceramics in the present work. In comparison with gelcasting method, green body with comparable strength has been achieved by this novel forming process, which is owing to the strong function of PVA gel caused by the freeze-thaw cycles. Herein, Si 3 N 4 hollow spheres are employed as pore-forming agent in order to achieve closed pores. The morphology of green body illustrates that pores originate from both hollow spheres and the space occupied by ice crystals, and the latter gives rise to the increase of porosity around 10%. Studies on the mechanical, dielectric and thermal properties of porous Si 3 N 4 ceramics dependent on freeze-thaw cycle and freezing time have been performed. It is found that porous ceramics treated for freeze-thaw 2 cycles with freezing time of 24 h present excellent properties, which are promising to be applied as radome materials. [ABSTRACT FROM AUTHOR]