Effects of Thermal Regeneration of Activated Carbon Fibers on Adsorption Characteristics for Toluene

Respiratory protective equipment is recommended as one method to diminish exposure to airborne pollutants , including volatile organic compounds (VOCs). Activated carbon fiber (ACF) has a potential use as an alternative adsorbent in respirators for VOCs. The advantages of ACF as an alternative absorbent include larger surface areas , higher adsorption capacities , thinner critical bed depth , higher number of micropores , faster heat and mass transfer properties , and its fabric form. When its saturation capacity is reached , the adsorbent is no longer effective for removing pollutants. To recover the ability to capture gaseous pollutants , carbon adsorbents typically are regenerated. The ACF's ability to be regenerated makes it a more cost effective , energy efficient and environmentally sustainable option to aid in certain purification processes. The purpose of this study was to investigate the effects of thermal regeneration on the adsorption characteristics of activated carbon fiber (ACF) in respirator cartridges for toluene and also to investigate the extent to which regeneration decreased the ACF's adsorption capacity and breakthrough time (BT). Results showed that the 10% and 50% BTs for the two tested ACF types (ACF 210 and ACF 605) were not significantly different (P = 0.06). However , the differences in 10% and 50% BT between the two toluene concentrations (200 and 500 ppm) were significant (P < 0.01) but the differences in 10% and 50% BT among the regeneration events were not statistically significant (P = 1.00). Consequently , ACF performed consistently well in adsorbing toluene to its full capacity even after multiple regenerations. The ACF's performance in this study displays its potential to serve as an alternative adsorbent to granular activated carbon (GAC) in respirators. Effective adsorbents in respirators need to consistently adsorb VOCs to their full capacity even after multiple regenerations. Additionally , they must have no loss in breakthrough times regardless of the concentration exposures to VOCs. These particular requirements allow ACF to be a potentially effective adsorbent in respirators