Citation:

Liu, X. Investigation on the direct transfer of SVOCs from source to settled dust: analytical model and key parameter determination. ACS Agricultural Science & Technology. American Chemical Society, Washington, DC, 56(9):5489-5496, (2022). https://doi.org/10.1021/acs.est.1c08257

Impact/Purpose:

Human exposure to semi-volatile organic compounds (SVOCs) can occur through various pathways including direct contacts through hand and other skin surfaces, ingestion through hand-to-mouth and diet activities, and inhalation of gases and airborne particles, which will pose adverse health effects. As an important exposure source, settled dust has attracted wide attention because of the complexity of its interactions with SVOCs. It is a challenging problem on how to accurately and conveniently measure key parameters including the dust diffusion coefficient and dust/air partition coefficient that control the mass transfer mechanisms between SVOCs and settled dust. This study develops an analytical model based on the experimental data and demonstrates the effectiveness of the developed analytical model to characterize the transport mechanism of direct contact between SVOC source materials and settled dust and to determine the key parameters. 

Description:

Settled dust is an important medium for semi-volatile organic compounds (SVOCs) transport indoors. Understanding the mechanism of interaction between SVOCs and settled dust can greatly reduce the exposure risk. This study develops an analytical model to elucidate the mechanism of direct contact between SVOC sources and settled dust. The model incorporates the adsorption of SVOCs onto indoor surfaces, which was ignored in previous numerical models. Based on this model, a hybrid optimization method is applied to determine the key parameters of SVOC transport, i.e., the diffusion coefficient in the dust, the dust/air partition coefficient, and the chamber surface/air partition coefficient. Experiments of direct contact between SVOC source materials containing organophosphorus flame retardants (OPFRs) and settled dust were conducted in chambers. The key parameters were determined by performing curve fitting using data collected from the OPFR chamber tests and from the literature for phthalates. The reliability and robustness of the model and measurement method are demonstrated by the high fitting accuracy and sensitivity analysis. The obtained key parameters are more accurate than those from empirical correlations in prior studies. Further analysis indicates that dust/air partition coefficient plays an important role and adsorption effect on surfaces cannot be neglected for SVOC transport.

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