Production and characterization of durable self‐cleaning and engineering porous Al₂O₃/CaAl₁₂O₁₉ ceramic membranes

Abstract

The rapid development of engineering filtering process suggests that it is imperative to produce membrane substrates with a fine pore size, high gas permeation, and antifouling properties for efficient and long-term application. This study reports on a novel fabrication method of a porous Al 2 O 3 /CaAl 12 O 19 ceramic membrane substrate by a direct foaming method combined with cement solidification and tape-casting technology. The microstructure of the produced ceramic membrane consisted of pores with a size of 50-150 μm, which were interconnected with each other with a large number of small filtering functional pores of <10 μm. By increasing the amount of the foaming agent, the porosity of the porous Al 2 O 3 /CaAl 12 O 19 ceramic membranes was tailored from 64.8% to 80.5%, and the bending strength decreased from 32.1 ± 1.0 to 9.6 ± 0.9 MPa, respectively. The sintered hydrophilic ceramic substrate was successfully modified to a hydrophobic one (with water contact angles of 143°) by pyrolysis of dimethyldichlorosilane and dichloromethylsilane. The resultant membrane displayed high chemical stability and self-cleaning features. The membrane with a porosity of 64.8% had a N 2 permeation of 3.0 (±0.5) × 10 7 L m −2 h −1 at 0.5 bar and a water flux which could be totally suppressed at a liquid entry pressure of 0.45 bar.

Highly permeable Al2O3 microfiltration membranes with holey interior structure achieved through sacrificial C particles

“…where ε is the porosity, m is the total mass of the membrane with only holey layer, m 0 is the mass of the single support, s is the area of the coated surface, h is the thickness of the holey layer, and ρ is the theoretical density of the Al 2 O 3 (3.99 g/ cm 3 ). 25 The reported values of porosity were the average of 10 specimens.…”

“…Ceramic membranes exhibit several advantages compared with polymeric membranes, including excellent mechanical and chemical stability, high pressure tolerance, suitability for a wide range of treatment environments, high flux, and long service life. [1][2][3][4][5] These superior characteristics make them preferable for the wastewater treatment, if it were not for the fact that they are of high cost. The primary materials for the fabrication of ceramic membranes include alumina, 6,7 titania, 8,9 zirconia, 5,10 silicon nitride, 11,12 and silicon carbide.…”

“…Membrane separation is one of the most efficient processes for water and wastewater treatment. Ceramic membranes exhibit several advantages compared with polymeric membranes, including excellent mechanical and chemical stability, high pressure tolerance, suitability for a wide range of treatment environments, high flux, and long service life . These superior characteristics make them preferable for the wastewater treatment, if it were not for the fact that they are of high cost.…”

A novel process to high‐strength and controlled‐shrinkage Al2O3 foams with open‐cell by Al powder hollowing technology

“…Such high‐performance ceramic material has proven to be satisfied the demands of many areas, for instance, energy, construction, transport, biomedical, and aerospace 4–6 . Nowadays, research on these materials focuses on the controlling of pore structure because complex and hierarchically porous have a significant influence on mechanical strength, 7,8 thermal and acoustic insulation, 9,10 filtration, 11–13 and catalytic supports 14 . Until now, many ways can be given to prepare ceramic foams, for example, sacrificial template, 15 replica, 16 direct foaming 17 (DF), and gelation freezing, 18 but the obtained materials face three problems: (i) single pore structure, (ii) very low mechanical properties when it has excessive porosity, 19 and (iii) high sintering shrinkage.…”

Fabrication and Characterization of Ice Templated Membrane Supports from Portland Cement

“…Recently, calcium aluminate cement, which is different than Portland cement, is also proved to be a promising material for membrane fabrication [17]. However, it would be better to avoid high-temperature sintering, where it is used for calcium aluminate membranes, for the sake of environmental protection [18].…”