Development of a model for the estimation of indoor volatile organic compounds concentration based on experimental sorption parameters

In order to model indoor air quality quantitatively, the adsorption and the desorption rate constants of toluene for four typical furnishing materials (namely, two polyacrylonitrile carpets, a cotton sofa and a polyester curt ain) were obtained by analyzing the toluene evaporation experiments in a te st chamber. The N-2-BET areas were also measured for these materials and th ey were found to be in the range of 0.5-1.5 m(2)/g. It was found that the c onstants, at 25 degrees C, ranged between 0.0009 and 0.0013 m* h(-1) for ad sorption and between 0.03 and 0.06 h(-1) for desorption, depending on the t ype of the material. These constants were then incorporated in a model for predicting the toluene concentration as function of time and the theoretica l results were compared with the measured data of a test house. The unstead y state mass-balance model which rook into account adsorption and desorptio n rates and assumed negligible external and internal mass-transfer resistan ces were found to be satisfactory. Mixing factors were used in expressing d eviations from complete mixing in the test chamber, and values around 0.7 w ere obtained experimentally by the SF6 tracer gas technique. The same techn ique was also used to measure the hourly air exchange rates in the test hou se.