Measuring partition and diffusion coefficients for volatile organic compounds in vinyl flooring (original) (raw)
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Measuring Concentrations of Volatile Organic Compounds in Vinyl Flooring
Journal of the Air & Waste Management Association, 2001
The initial solid-phase concentration of volatile organic compounds (VOCs) is a key parameter influencing the emission characteristics of many indoor materials. Solid-phase measurements are typically made using solvent extraction or thermal headspace analysis.
Predicting the Emission Rate of Volatile Organic Compounds from Vinyl Flooring
Environmental Science & Technology, 2002
A model for predicting the rate at which a volatile organic compound (VOC) is emitted from a diffusion-controlled material is validated for three contaminants (n-pentadecane, n-tetradecane, and phenol) found in vinyl flooring (VF). Model parameters are the initial VOC concentration in the material-phase (C 0 ), the material/air partition coefficient (K), and the material-phase diffusion coefficient (D). The model was verified by comparing predicted gas-phase concentrations to data obtained during small-scale chamber tests, and by comparing predicted material-phase concentrations to those measured at the conclusion of the chamber tests.
CLEAN - Soil, Air, Water, 2009
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 398C) 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.
VOC Sink Behaviour on Building Materials - Model Evaluation
Indoor and Built Environment, 2011
The event of 11 September 2001 underscored the need to study the vulnerability of buildings to weapons of mass destruction (WMD), including chemical, biological, physical, and radiological agents. Should these agents be released inside a building, they would interact with interior surfaces, building materials, and furnishings, and could remain for a long period in an indoor environment. In this study, the sink effect was investigated with building materials (e.g. painted gypsum wallboard, vinyl flooring, carpet, mortar) and volatile organic compounds (VOCs), ethylbenzene, 1-butanol, decane, and dodecane, which were used as surrogates of toxic chemicals. It is observed that vinyl flooring has the strongest sink for ethylbenzene and dodecane. The sink experimental data were employed to evaluate the Langmuir-isotherm and diffusion sink models. Test data were also compared to a no-sink model. The sorption and desorption rate constants for the Langmuir-isotherm model were obtained. Mass balance was analyzed. There were strong correlations between equilibrium partition coefficients from the Langmuir-isotherm model and equilibrium partition coefficients and the effective diffusion coefficients from the sink diffusion model. This study provides insights into the sink effect and absorption mechanisms of VOCs in indoor environments.
Indoor Air, 2013
Accumulation of volatile organic compounds (VOCs) that migrate inside buildings from underlying contaminated soils and groundwater poses human health risks. VOCs intrusion into buildings driven only by diffusion was reproduced by a laboratory-scale experiment. Effective diffusion coefficients and fluxes of a group of selected chlorinated solvents and BTEX through two types of isolation materialthat is, concrete (anhydrite screed) and geo-membranewere estimated. The laboratory experiment indicated that the diffusive transfer of pollutants through sediments into indoor air of buildings cannot be prevented by building sealing material, but it could be attenuated to a certain degree by concrete and up to non-detectable levels by the geo-membrane. Effective diffusion coefficients through concrete and geo-membrane ranged from 3.17 9 10 À2 to 5.90 9 10 À5 cm 2 /s and from 5.47 9 10 À6 to 5.50 9 10 À8 cm 2 /s, respectively.
The Interaction of Vapour Phase Organic Compounds with Indoor Sinks
Indoor Air, 1991
The interactwn of indoor air pollutants with interior surjaces (i.e., sinks) is a well known, but pootly understood, phenomenon. Studies have shown that re-emisswns of adsorbed organic vapours can concribUte to elevated concentratirms of organics in indoor environments. Research is being conducted in small environmental test chambers to develop data for predicting sink behaviout: This paper reports on the development of sink models based on fundamental mass transfer thew. The results of experiments Conducted to determine the magnitude and rate of adsorption and desurptwn of vapour phase organic compounds for several materials are presented. Five materials were evaluated: carpet, painted wallboard, ceding tile, window g h s , and upholstey. Two organic compounds were tested with each material: tetrachhethyhe (a common cleaning solvent) and ethylbenzene (a c o m m constituent of petrohm-based solvents w&b used in consumer products). The results of the experimental work are presented showing the relevant sink effect parameters for each material tested and comparing the stive behaviour of the two organic compounds evaluated. An indoor air quality (IAQJ model was mdij5ed to incorporate adsorption and desoqtion sink rates. The model was used to predict the temporal hlstoty of
Key factor analysis of VOC sorption and its impact on indoor concentrations: The role of ventilation
Building and Environment, 2012
Previous volatile organic compound (VOC) sorption studies by building materials have been mainly conducted under a set of standard environmental conditions (e.g., 23 C, 50% relative humidity and 1 air changes per hour (ACH)). However, the conditions around a material in actual buildings are usually different from such standard conditions, especially the ventilation rate. The objective of this study is to analyze quantitatively the effect of ventilation rate on VOC sorption under various conditions. By conducting several representative simulation case studies using a model that was previously validated, it is concluded that ventilation is a key factor for determining whether sorption effect in building materials should be considered. When the ventilation rate is small (e.g., 0.1 ACH), the sorption effect of materials with strong sorption capacity such as carpet and cushion should be considered. On the other hand, sorption for most materials may be neglected when ventilation rate reaches a high level (e.g., 20 ACH). The results could be useful in indoor air quality simulation and design.
VOC adsorption on material: influence of gas phase concentration, relative humidity and type of VOC
2005
This paper presents the results of a factorial experiment design analysis to investigate volatile organic compounds (VOC) adsorption on a ceiling tile. The impacts of three factors, VOC gas phase concentration, relative humidity, and VOC type, as single parameters and as a combination, on adsorption have been investigated. Cyclohexane, toluene, ethyl acetate, isopropyl alcohol and methanol were the five VOCs used in this study. A factor significant level was determined through evaluating its F value and comparing it with the critical value of F distribution at 95% confidence level. It was found that: (i) neither the relative humidity and gas phase concentration nor any interaction effect between them had significant impacts on toluene adsorption on the ceiling tile; (ii) the adsorption isotherm appeared to be linear for the non-polar compounds and non-linear for the semi-polar and polar compounds; (iii) no significant impact of relative humidity on adsorption was observed for most VOC compounds except for methanol; and (iv) the ceiling tile had the highest adsorption capacity toward the polar compounds, followed by the aromatic compounds and aliphatic compounds. In addition, the statistical analysis regarding the experimental results of toluene as a single compound or as a part of a mixture showed that toluene adsorption capacity on the ceiling tile as a single compound was higher than as a part of a mixture.
Indoor Air, 2006
An extensive literature review of research on the impact of indoor air conditions: temperature, relative humidity and surface air velocity on materials emission rates is presented. This paper also presents the results of an experimental work CO study the impact of room air temperature and relative humidity on materials emission rates. The results indicate that both the temperature and relative humidity have a significant effect on the emissions from paint and varnish. In the case of varnish, the results were consistent with earlier results. However, the paint results show inconsistent emission behaviour. Further, for both materials, the individual compounds did not necessari!v,follow the same trend established for the TVOC. 0