Vapor adsorption characteristics of toluene in an activated carbon adsorbent-loaded nonwoven fabric media for chemical filters applied to cleanrooms

Abstract

Chemical filters are used extensively in the cleanrooms of the semiconductor factories to remove airborne molecular contamination (AMC). Adsorption by activated carbons (AC) as media within the chemical filter is one of the practical methods for removal of gaseous contamination in a cleanroom. The objective of this study is to evaluate coconut shell activated carbon adsorbent-loaded nonwoven fabric media performance by determining the breakthrough curves, the linear driving force (LDF), the intra-particle diffusion characteristics, the empty bed contact time (EBCT) and the bed depth service time (BDST), the mass-transfer zone (MTZ), and pressure drop. The testing conditions were maintained at 28 ± 1 °C, and relative humidity at 40 ± 2% with face velocities of 0.076, 0.114 and 0.152 m/s for removal efficiency and capacity determination. The challenge gas concentrations of toluene were fixed at 10, 31, 42 and 70 ppm to accelerate the breakthrough of media adsorption. The concentrations were measured by a real-time photoionization detector. Results showed that breakthrough curves correlate to the challenge vapor concentration and the face velocity. Saturated adsorption ratio was increased with raised challenge gas concentration and increased face velocity significantly.