A research team led by O Kyong Ryol, a section head at the Nano Physics Engineering Institute, has developed low-cost ceramic membranes.
Thanks to their unique advantages such as high separation efficiency, excellent thermal and chemical stability and low energy consumption, ceramic membranes have found wide application in gas separation and water purification, and in foodstuff, pharmaceutical and chemical industries.
A ceramic separation membrane is considered as a compound of gradually smaller porous materials, which generally consists of several thin separation layers on a porous support.
In the past years, most ceramic membranes were fabricated as porous ceramic supports with materials such as Al2O3, ZrO2 and SiC or their composites. However, both expensive starting materials and high cost of production processes restricted their extensive applications in industrial fields.
In order to reduce the fabrication cost, they have developed natural kaolin-based ceramic membranes.
Among these porous mineral-based materials, porous mullite ceramics have superior advantages such as good chemical and thermal durability, low expansion coefficient and excellent mechanical properties. These characteristics put them in use as ceramic membrane supports and catalyst supports.
For improvement of the porosity of supports, they are generally prepared by adding pore-forming agents such as corn starch and graphite, but these methods cost a lot and have some defects.
Therefore, as an attempt to solve such problems, they prepared low-cost porous mullite ceramic membrane supports with 2nm pores by extrusion and reaction sintering, with natural mineral kaolin as raw material and Al(OH)3 as a pore-forming agent.
Low-cost porous ceramic membranes are useful filtration components in a number of applications fields, and they will find use in removing contaminants of several micrometers in size down to nanometer range from various fluids.
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