The effect of sacrificial templates on the pore characteristics of sintered diatomite membranes

Abstract

Recently, porous ceramic membranes have become an interesting subject due to their outstanding thermal and chemical stability. Among the many types of ceramics, as diatomite is inherently porous and irregular, it is worthwhile to investigate the relationship between the characteristics of sacrificial templates and porous microstructures after sintering. Therefore, sintered diatomite membranes were prepared with 8¯m solid polymer spheres, 20¯m solid polymer spheres, wheat starch, and light clusters of aggregated carbon nanotubes while varying the amount of sacrificial template material by dry pressing at 25 MPa. The results show that the characteristics of the sacrificial templates, e.g., the rigidity, directly affect the pore characteristics and accordingly determine the permeability of sintered diatomite membranes. Also, we discuss whether the largest pore sizes and average pore sizes of the sintered diatomite membranes reflect the actual permeability appropriately.

Preparation processes and characterizations of alumina-coated alumina support layers and alumina-coated natural material-based support layers for microfiltration

“…In this study, we achieved the following goals: (1) We determined the air permeability of the diatomite support layer [14,19,22]. (2) We evaluated the air permeability of a diatomite-coated diatomite support layer [20].…”

“…The mechanical strength of a diatomite support layer is not acceptable for a free-standing membrane, therefore, we introduced kaolin to tailor the pore characteristics of the diatomite support layer. Previously, we reported possible approaches for fabrication of a diatomite-based support layer that allowed fine-tuning of the pore characteristics [13][14][15][16][17][18][19][20][21][22].…”

The preparation and pore characteristics of an alumina coating on a diatomite-kaolin composite support layer

“…These approaches enabled (1) the enhancement of the permeability of the diatomite support layer beyond that achieved by controlling the sintering temperature, 21) (2) the reduction of the largest pore size of the diatomite support layer by forming a diatomite-kaolin composite, 22) and (3) the reduction of the largest pore size of the diatomite support layer by depositing a diatomitekaolin composite coating. 23) If an inexpensive natural material composite support layer, such as the diatomite-kaolin composite support layer used in this study, can be coated with a limited amount of an expensive highpurity alumina, an alumina-coated diatomite-kaolin composite support layer can be used as an intermediate platform to replace the expensive high-purity alumina support layer.…”

Successful preparation of self-setting particle-stabilized zeolite 13X foams

“…In contrast to the negligible permeability of the particle-stabilized zirconia foam (0.46 liter/min/cm 2 at 175 kPa), which has a closed-pore structure, the self-setting particle-stabilized zeolite 13X foam with 5 wt.% of lithium carbonate which has an interconnected pore structure, has an appropriate permeability (9.08 liter/min/cm 2 at 175 kPa) compared to the ceramic membranes for microfiltration such as the sintered diatomite membranes (1.452.80 liter/min/cm 2 at 175 kPa), 23) the sintered diatomitekaolin composite membranes (1.132.87 liter/min/cm 2 at 175 kPa), 24) and the sintered particle-stabilized diatomite foam (3.70 7.29 liter/min/cm 2 at 60 kPa). 25) As we added 50 wt.% of commercial calcium aluminate cement to the particle-stabilized zeolite 13X foam to give a self-setting ability, the micropores of self-setting particle-stabilized zeolite 13X foam could be partially filled or covered with hydration reaction products. Therefore, the pore volume of a self-setting particle-stabilized zeolite 13X foam with 5 wt.% of lithium carbonate, as-received zeolite 13X powder and asreceived calcium aluminate cement powder were measured.…”