The adsorption and subsequent desorption of volatile organic compounds from the walls, ducts, and air-conditioning system of a large indoor air research environmental chamber have been investigated. Contaminants were volatilized into the chamber, then flushed from the chamber after an equilibration period. The mass of each contaminant adsorbed by chamber surfaces was calculated by a mass balance method. The adsorption ratio, defined as the mass adsorbed divided by the mass in the air at the end of the equilibration period, was determined for three chamber operation modes. Adsorption (k_a) and desorption (k_d) rate constants were determined by fitting the concentration data to a model. Adsorption ratios calculated by the mass balance method are comparable (r~2 chemical bounds 0.94) with equilibrium adsorption ratios determined from the product of the adsorption ratio constants (k_a/k_d) and test chamber surface to volume (S/V) ratio. Test results show that adsorption of normal alkanes by the large chamber is approximately a factor of 10 lower than that reported for the same compounds in small environmental chambers made of glass and stainless steel.
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