An Experimental Study for Examining the Effects of Environmental Conditions on Diffusion Coefficient of VOCs in Building Materials

作者：Farajollahi Yashar; Chen Zhi; Haghighat Fariborz^*

来源：Clean-Soil Air Water, 2009, 37(6): 436-443.

DOI：10.1002/clen.200900053

• Ceiling tiles
• Diffusion coefficient
• Diffusivity
• Indoor Air
• Volatile organic carbon (VOC)

The diffusion coefficients (diffusivity) of five different volatile organic carbon compounds (VOCs), i.e., octane, isopropanol, cyclohexane, ethyl acetate, and hexane, were experimentally determined for a building ceiling tile. The effects of typical indoor environmental conditions on the diffusivity of the VOCs in the tile were evaluated over a range of temperatures (15, 23, 31 and 39 degrees C) and at three relative humidity percentages (0, 20, and 40%). Three novel methods were developed during the course of this study: (i) a two-chamber experimental apparatus for diffusivity testing of building materials, (ii) a GC/MS method for determining the above VOCs, and (iii) a two-factor method for analyzing the statistical significance effects of temperature and humidity on VOC diffusivity. The results showed that the diffusion coefficients of the VOCs were positively related to their vapor pressure, but not to their boiling point, molecular weight or polarity index. No difference was observed between the diffusion coefficient of a VOC present alone or as part of a mixture of VOCs. Temperature and humidity (in the range of a typical indoor environment) had minor significant effects on the diffusion coefficient, with temperature being more important than humidity. It is hypothesized that water vapor molecules may occupy the pores of the ceiling tile material under conditions of high relative humidity and prevent the VOC molecules from diffusing through the pores.

• 出版日期2009-6