Preparation And Filtration/Adsorption Properties Of Mullite-based Porous Ceramics With Network Of Pore Walls

Mullite porous ceramics have the characteristics of high temperature resistance,corrosion resistance,large specific surface area and high porosity,and are widely used in the field of adsorption and filtration.However,these conventional mullite porous ceramics suffer from inevitable drawbacks such as high cost,complicated preparation methods,and low specific surface area,which hinder its filtration and adsorption performance and limit their application.Coal gangue is a solid waste,and contains a large amount of Si O2 and Al2O3,which can be used as a raw material for preparing mullite porous ceramics.First,to solve the above problems,polyurethane foam technology was used to prepare mullite porous ceramics with three-dimensional network of pore walls using alumina and silica fine powder as raw materials.The effects of solid loading and sintering temperature on the pore structure,microstructure and mechanical properties of mullite porous ceramics were studied.It was found that when the solid loading was 61 wt%,three-dimensional uniform distributions of pore structures and more complete pore morphology could be obtained.After calcining the sample at 1400 ℃ for 2 h,mullite porous ceramics with porosity up to about 85.3% and compressive strength about 3.0 MPa can be obtained.Besides,the sample was tested for room temperature particulate matter(PM)filtration performance,and it was found that the removal efficiency of PM could reach 89% within 60 mins,and the pressure drop was only 33 Pa.Secondly,mullite porous ceramics are expensive to prepare,which severely limit its application range.To reduce its preparation cost,coal gangue/mullite-based porous ceramics with three-dimensional network pore walls were prepared by using coal gangue powder and alumina as raw materials and mixing them in a ratio of n Al : n Si = 3 : 1.The effects of solid loading and sintering temperature on the pore structure,microstructure,and mechanical properties of gangue/mullite-based porous ceramics were studied.It was found that when the solid loading was 54 wt%,three-dimensional uniform distributions of pore structures and more complete pore morphology could be obtained.After calcining the sample at 1300 ℃ for 2 h,coal gangue/mullite-based porous ceramics with porosity up to about 87.0% and compressive strength about 1.9 MPa can be obtained.Also,the effect of temperature on the porosity of the sample is small.When the temperature is 1600 ℃,the porosity of coal gangue/mullite-based porous ceramics only decreases by 0.6%.The sample was tested for PM filtration performance,and we found that the removal efficiency of PM is only 3.0% at the highest.Finally,to further reduce the preparation cost of mullite porous ceramics and expand its application fields.In this work,coal gangue powder was used as the main raw material to prepare coal gangue-based porous ceramics with three-dimensional network pore wall structures.The effects of solid loading and sintering temperature on the pore structure,microstructure,and mechanical properties of gangue-based porous ceramics were studied.It was found that when the solid loading was 49 wt%,three-dimensional uniform pore structure distributions and more complete pore morphology could be obtained.After being calcined at 1000 ℃ for 2 h,reticular structures can be obtained with a porosity of about 87.0% and a compressive strength of 0.13 MPa.The sample was tested for dye adsorption and PM filtration performance,and we found that the removal efficiency of methylene blue could be reached 94.9%.Furthermore,the removal efficiency of PM can reach 75%,but the pressure drop is only 40 Pa in an hour.