Page:Current Strategies for Engineering Controls in Nanomaterial Production and Downstream Handling Processes.pdf/30

 Figure 5. Four primary filter collection mechanisms

These mechanisms apply mainly to mechanical filters and are influenced by particle size. Impaction and interception are the dominant collection mechanisms for particles greater than 0.2 μm, and diffusion and electrostatic attraction are dominant for particles less than 0.2 μm, including nanomaterials. The combined effect of these collection mechanisms results in the classic collection efficiency curve, shown in Figure 6.

Figure 6. Collection efficiency curve, i.e., fractional collection efficiency versus particle diameter for a typical filter (Used with permission from Lee and Liu [1980].) Current Strategies for Engineering Controls in Nanomaterial Production and Downstream Handling Processes