Measurement of diffusion coefficients of VOCs for building materials: review and development of a calculation procedure

Haghighat, Fariborz; Lee, C.-S.; Ghaly, Wahid

doi:10.1034/j.1600-0668.2002.1e008.x

Cited by 92 publications

(69 citation statements)

References 12 publications

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“…Moreover, the results obtained experimentally by the modified dry cup method fall within the existing values in the literature, obtained by other methods subject to similar gradients of concentrations, close to the values of indoor environments, like the method of twin chambers [10]. Furthermore, the values obtained by the wet cup method are of the same order of magnitude to those found by other authors who used the same method [1,7].…”

Section: Resultssupporting

confidence: 86%

“…However some facts were the same: the gypsum board presents the higher values of D and PVC the lower values of D for the three compounds studied in both methods. These differences could be explained by the influence of concentration on diffusion coefficients [1,8], which is very different in the two methods: the saturation concentration in the wet cup method (of the order of hundreds g/m 3 ) and typical concentrations of indoor environment in the modified dry cup method (of the order of several mg/m 3 ). Moreover, the results obtained experimentally by the modified dry cup method fall within the existing values in the literature, obtained by other methods subject to similar gradients of concentrations, close to the values of indoor environments, like the method of twin chambers [10].…”

Section: Resultsmentioning

confidence: 99%

“…Thus, it is expectable that the wet cup method will overestimate the diffusion coefficient. Haghighat et al [1] propose the use of the "dry cup method", in opposition to the "wet cup method".…”

Section: Methodsmentioning

confidence: 99%

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Presentation of a New Method for Determination of Diffusion Coefficients of Gaseous Pollutants in Cladding Wall Materials Indoors

Gonçalves

Santos

Silva

et al. 2010

DDF

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Abstract. Diffusion and partition coefficients are two key parameters of importance for the characterization of building materials as sources and sinks of air pollutants indoors. The number of coefficients for each pair 'chemical compound -material surface' available in the literature are still scarce and with a high discrepancy in the results obtained by different methods, even for the same method [1]. The objectives of this study were (1) to develop a simple and rapid experimental method for directly measuring the diffusion coefficient (D), and (2) to perform determinations with both the new and the cup method comparing the results obtained. The new method is based on two existent methodologies, the passive sampling on Tenax TA and the dry cup method, proposed by Haghighat et al. [1] and also developed by this research team [2]. The experiments were carried for three different building materials (cork based material, gypsum board and PVC) and three different compounds (cyclohexane, n-octane and m-xylene). The discussion of the results obtained for D by the two methods is presented in this paper. Observed differences were not of the same order of magnitude for the pairs compound/material studied, varying from the order of 10 1 in the case of PVC to 10 2 in the gypsum and in the cork. However some facts were the same: the gypsum board presents the higher values of D and PVC the lower values of D for the three compounds studied in both methods. One of the causes of these marked differences could be high difference of the concentration of the compound in the air between the methods, saturation value in cup method (dozens g/m 3 ) and low values typical from indoor environments (few mg/m 3 ) in the proposed method. IntoductionThe quality of the indoor environment of non-industrial buildings has been receiving a growing interest from the scientific community due to the implications of the 'non quality' on the health and well being of the occupants. Many studies present construction and cladding materials as main sources of indoor air pollution, particularly of volatile organic compounds (VOC).In this context the development of mathematical models for the prevision of the concentration of pollutants in real situations requires the previous study of the behaviour of the materials vs pollutants to quantify the parameters involved, represented namely by the diffusion coefficients and partition coefficients [3]. The available data in the literature for those coefficients is still scarce and, in general, with highly dispersed values. The main objective of the present work was to develop a new method for determination of D. The values of D were also determined by the cup method for comparison. Research methodsDiffusion is the mode of mass transfer of a compound caused by a concentration gradient. Diffusion transport of gases in building materials involves a complex variety of processes including molecular, Knudsen and surface diffusion within the porous interstices [4]. Several experimental techniques have been used to esti...

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Section: Resultssupporting

confidence: 86%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Presentation of a New Method for Determination of Diffusion Coefficients of Gaseous Pollutants in Cladding Wall Materials Indoors

Gonçalves

Santos

Silva

et al. 2010

DDF

View full text Add to dashboard Cite

show abstract

“…It is based upon Fick's 1 st law [8]. The main disadvantage of this method is that the liquid VOC placed in the cup creates a concentration of saturation, which is unrealistically high for indoor air quality application, with values of around dozens of g/m 3 [2]. Thus, it is expected that the cup method will overestimate the diffusion coefficient.…”

Section: Methodsmentioning

confidence: 99%

“…Thus, it is expected that the cup method will overestimate the diffusion coefficient. Haghighat et al [2] proposed the use of this method with a modification, and called it the "dry cup method", in contrast to the old "wet cup method". In the dry cup method, a desiccant, e.g.…”

Section: Methodsmentioning

confidence: 99%

Improvement of the Modified Dry-Cup Method for Determination of the Diffusion Coefficients of Gaseous Pollutants in Building Materials

Gonçalves

Silva

Santos

et al. 2010

DDF

View full text Add to dashboard Cite

Diffusion and partition coefficients are key parameters for the characterization of building materials as sources and sinks of air pollutants indoors. A simple and rapid experimental method for direct measurement of the diffusion coefficient (D) was presented in a previous article [1]: the modified dry cup method. This method was based upon two existent methodologies, the passive sampling on Tenax TA and the dry cup method, proposed by Haghighat et al. [2]. In the present article, some improvements were made in the experimental set-up in order to obtain more precise results. The previous cup was modified by increasing the number of Tenax tubes, connected to the bottom of the cup, from one to five. The results obtained with both cups were compared. Measurements with single compounds and with three compounds simultaneously were compared in order to evaluate the influence of competition between molecules of different compounds.

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Internal diffusion and re‐emission of leaked liquid ethyl acetate from mortar materials

Harashima

Sumiyoshi

Ito

2022

Japan Architectural Review

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Assuming the leakage of hazardous liquid chemicals in factories and chemical plants caused by natural disasters or human error, it is important to precisely estimate exposure risk and design appropriate evacuation plans and risk‐reduction measures. The exposure risk of indoor residents to leaked chemicals may be estimated using direct measurements or theoretical/numerical estimations of gas‐phase concentrations. Although mathematical models of gas‐phase concentration in the workplace are essential for predicting exposure concentrations at the design stage, practical models have not yet been fully established. We previously proposed practical numerical models to assess indoor gas‐phase concentration distributions after the accidental leakage of liquid chemicals using liquid toluene as a representative hazardous chemical. In this study, the leakage of liquid ethyl acetate, a commonly used organic solvent, into mortar flooring was reproduced in a small test chamber, and numerical analysis was performed. The results showed that the time history of the chamber exhaust concentration had a sharp peak and differed significantly from that of toluene. Three‐dimensional computational fluid dynamics (CFD) analysis incorporating practical ethyl acetate emission models reproduced the external and internal emission characteristics of leaked ethyl acetate on the mortar material. The models showed reasonable agreement with the experimental data.

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Measurement of diffusion coefficients of VOCs for building materials: review and development of a calculation procedure

Cited by 92 publications

References 12 publications

Presentation of a New Method for Determination of Diffusion Coefficients of Gaseous Pollutants in Cladding Wall Materials Indoors

Presentation of a New Method for Determination of Diffusion Coefficients of Gaseous Pollutants in Cladding Wall Materials Indoors

Improvement of the Modified Dry-Cup Method for Determination of the Diffusion Coefficients of Gaseous Pollutants in Building Materials

Internal diffusion and re‐emission of leaked liquid ethyl acetate from mortar materials

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