title: Breakthrough curves for toluene adsorption on different types of activated carbon fibers: application in respiratory protection.
abstract: Activated carbon fibers (ACF) are considered viable alternative adsorbent materials in respirators because of their larger surface area, lighter weight, and fabric form. The purpose of this study was to characterize the breakthrough curves of toluene for different types of commercially available ACFs to understand their potential service lives in respirators. Two forms of ACF, cloth (AC) and felt (AF), with three surface areas each were tested. ACFs were challenged with six toluene concentrations (50-500 p.p.m.) at constant air temperature (23°C), relative humidity (50%), and air flow (16 l min-1) at different bed depths. Breakthrough data were obtained using continuous monitoring by gas chromatography using a gas sampling valve. The ACF specific surface areas were measured by an automatic physisorption analyzer. Results showed unique shapes of breakthrough curves for each ACF form: AC demonstrated a gradual increase in breakthrough concentration, whereas AF showed abrupt increase in concentration from the breakpoint, which was attributed to the difference in fiber density between the forms. AF has steeper breakthrough curves compared with AC with similar specific surface area. AC exhibits higher 10% breakthrough times for a given bed depth due to higher mass per bed depth compared with AF, indicating more adsorption per bed depth with AC. ACF in respirators may be appropriate for use as protection in environments with toluene concentration at the Occupational Safety and Health Administration Permissible Exposure Limit, or during emergency escape for higher toluene concentrations. ACF has shown great potential for application in respiratory protection against toluene and in the development of thinner, lighter, and more efficient respirators.
authors.affiliation: 1.Environmental Health Sciences Program, Department of Health Education and Promotion, East Carolina University, 300 Curry Court, 3407 Carol Belk Building, Greenville, NC 27858, USA balanayj@ecu.edu.
authors.forename: Jo Anne G
authors.initials: JA
authors.lastname: Balanay
authors.affiliation: 2.Department of Occupational and Environmental Health, University of Oklahoma, 801 N.E. 13th Street, Room 419, Oklahoma City, OK 73126, USA.
authors.forename: Evan L
authors.initials: EL
authors.lastname: Floyd
authors.affiliation: 3.Department of Environmental Health Sciences, University of Alabama at Birmingham, RPHB 530, 1530 3rd Avenue S., Birmingham, AL 35294, USA.
authors.forename: Claudiu T
authors.initials: CT
authors.lastname: Lungu
mesh_terms: D000327:Adsorption; D016902:Air Pollution, Indoor / Q000517:prevention & control; D002244:Carbon / Q000032:analysis* / Q000737:chemistry; D000077482:Carbon Fiber; D008855:Microscopy, Electron, Scanning; D015233:Models, Statistical; D016273:Occupational Exposure / Q000517:prevention & control; D012134:Respiratory Protective Devices; D013499:Surface Properties; D013784:Textiles; D014050:Toluene / Q000737:chemistry*; D014481:United States
chemical_list: D000077482:Carbon Fiber; D014050:Toluene; D002244:Carbon
keywords: activated carbon fiber; adsorption; breakthrough; respirators; respiratory protection; service life; toluene