Use of Carbon Nanotube Filter in Removing Bioaerosols

Tianjia Guan and MAOSHENG YAO

State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering Peking University, Beijing 100871, China

     Abstract Number: 168
     Last modified: November 7, 2009

Abstract
In this study, the carbon nanotube (CNT) filters were created by depositing both single-walled and multi-walled CNT with loadings of 0.2-1.6 ug/cm2 on polypropylene and polyamide membrane supports with pore size of 5 and 10 um. Bacillus subtilis, Pseudomonas fluorescens and NaCl were aerosolized and collected using a Button Aerosol Sampler loaded with the CNT filters. The physical efficiencies of the CNT filters with different CNT loadings when removing the aerosols were studied using an Optical Particle Counter. The influences of acid washing on the efficiencies of CNT filters were also investigated.

The removal efficiencies of CNT filters prepared on polypropylene membrane supports when collecting B. subtilis aerosols were shown to range from 10 to 95% in average for the CNT loadings of 0.2-1.6 ug/cm2 . When collecting aerosolized P. fluorescens, the efficiencies were shown to range from 5 to 60% given similar CNT loadings on the membrane support. The results revealed that membrane types and pore sizes tested as well as CNT types did not significantly affect the performance of CNT filters. When collecting aerosolized NaCl, the efficiencies were observed relatively lower, i.e., below 50% for loadings of 0.3-1.5 ug/cm2 . Acid-rinsing was shown to exhibit some influences on the removal efficiency of single-walled CNT filters when collecting aerosolized NaCl. On the other hand, the membrane supports used in this study were shown to have stable passage efficiency of about 70% after 30 min sampling of B. subtilis aerosols. The performances of CNT filters prepared were shown to vary greatly, which was likely due to the CNT loading efficiency, membrane support filtration variance and the CNT uniformity on the support.

This study was the first to report efficiencies of CNT filters in removing biological aerosols and the information here is useful in both bioaerosol study and air cleaning technology.