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Henry’s Law Constant and Overall Mass Transfer Coefficient for Formaldehyde Emission from Small Water Pools under Simulated Indoor Environmental Conditions
Citation:
Liu, X., Z. Guo, N. Roache, C. Mocka, M. Allen, AND M. Mason. Henry’s Law Constant and Overall Mass Transfer Coefficient for Formaldehyde Emission from Small Water Pools under Simulated Indoor Environmental Conditions. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 49(3):1603-1610, (2015).
Impact/Purpose:
The aim of this study was to determine the HLC and the overall mass transfer coefficient for formaldehyde needed to model the behavior of formaldehyde released from biocides under various conditions of usage.The HLC and overall mass transfer coefficient obtained from this work can be used as key input parameters to evaluate and develop improved emission models for formaldehyde from biocides in occupational and residential settings.
Description:
The Henry’s law constant (HLC) and the overall mass transfer coefficient are both important parameters for modeling formaldehyde emissions from aqueous solutions. In this work, the apparent HLCs for aqueous formaldehyde solutions were determined in the concentration range from 0.01 % to 1 % (w/w) and at different temperatures (23, 40 and 55 °C) by a static headspace extraction method. The aqueous solutions tested included formaldehyde in water, formaldehyde-water with nonionic surfactant, Tergitol™ NP-9, and the anionic surfactant, sodium lauryl sulfate. Overall, the HLCs that were measured ranged from 8.93 × 10-6 to 1.12 × 10-4 (gas-concentration/aqueous-concentration, dimensionless). Fourteen small chamber tests were conducted with the formaldehyde solution in a small pool. By applying the measured HLCs, the overall liquid-phase mass transfer coefficients (KOLs) were determined to be in the range of 8.12 × 10-5 to 1.10 × 10-4 m/h, and the overall gas-phase mass transfer coefficients were between 2.84 and 17.9 m/h. The influence of the formaldehyde concentration, temperature, agitation rate, and surfactant on the HLC and the KOL was investigated. The results from this study provided data needed for assessing indoor exposure to formaldehyde originating from the use of household products that contain formaldehyde-releasing biocides.
URLs/Downloads:
http://dx.doi.org/10.1021/es504540c
HLC-EST-PAPER-08252014.PDF (PDF, NA pp, 559.655 KB, about PDF)