Filtration of nano-particles by a gas-solid fluidized bed

Area of Science:

• Environmental Engineering
• Particle Technology
• Filtration Science

Background:

• Nanoparticle filtration is crucial for air quality control.
• Fluidized beds offer a dynamic approach to particle removal.
• Understanding material interactions is key for efficient filtration.

Purpose of the Study:

• To investigate the filtration of 80 nm silicon dioxide (SiO2) and aluminum oxide (Al2O3) nanoparticles using fluidized beds.
• To compare the performance of silica sand and activated carbon (A.C.) as bed materials.
• To analyze the dynamic nature of filtration and its impact on removal efficiency over time.

Main Methods:

• Utilized fluidized beds with silica sand and A.C. as filtration media.
• Introduced a gas stream containing 80 nm SiO2 and Al2O3 particles.
• Monitored particle removal efficiency and its variation over time due to elutriation.

Main Results:

• Silica sand provided steady removal efficiencies of 86-93% for both SiO2 and Al2O3.
• A.C. filtration was dynamic; Al2O3 efficiency dropped from 92% to 80%, and SiO2 from 83% to 40%.
• Higher voidage in A.C. and particle segregation affected nanoparticle removal, particularly for SiO2.

Conclusions:

• Silica sand offers stable and comparable filtration for both SiO2 and Al2O3 nanoparticles.
• Activated carbon's high surface area is offset by dynamic filtration issues and particle segregation, leading to lower and variable efficiencies.
• Fluidized bed material selection significantly impacts nanoparticle filtration dynamics and overall effectiveness.