title: Kinetics and equilibrium partitioning of dissolved BTEX in PDMS and POM sheets.
abstract: Passive sampling of volatile organic chemicals from soil and groundwater is primarily important in assessing the status of environmental contamination. A group of low molecular weight pollutants usually found in petroleum fuels, benzene, toluene, ethylbenzene, and xylenes (BTEX) was studied for its kinetics and equilibrium partitioning with single-phase passive samplers using polydimethylsiloxane (PDMS) and polyoxymethylene (POM) as sorbing phase. PDMS (1 mm) and POM (0.076 mm) sheets were used for sorption of BTEX and concentrations were analyzed using GC-FID. The equilibrium absorption and desorption of PDMS in water was achieved after 120 min while POM sheets absorbed up to 35 days and desorbed in 7 days. The kinetic rate constants in PDMS is higher than in POM up to 3 orders of magnitude. Logarithms of partition coefficient were determined to be in the range of 1.6-2.8 for PDMS and 2.1-3.1 for POM. The results indicate that POM is a stronger sorbent for BTEX and has slower equilibration time than PDMS. The partitioning process for both polymers was found to be enthalpy-driven by measurement of K d values at varying temperatures. K d values increase at low temperature and high ionic strength conditions. Presence of other gasoline components, as well as dissolved organic matter, did not significantly affect equilibrium partitioning. A good 1:1 correlation between the measured and the predicted concentrations was established on testing the potential application of the constructed PDMS sampler on natural soils and artificial soils spiked with gasoline-contaminated water.
authors.affiliation: Department of Environmental Engineering, Daegu University, 201 Daegudae-ro, Gyeongsan-si, Gyeongsanbuk-do, 38453, Korea.
authors.forename: Go-Un
authors.initials: GU
authors.lastname: Nam
authors.affiliation: Department of Environmental Engineering, Daegu University, 201 Daegudae-ro, Gyeongsan-si, Gyeongsanbuk-do, 38453, Korea.
authors.forename: Riza Gabriela
authors.initials: RG
authors.lastname: Bonifacio
authors.affiliation: Division of Environmental Science and Ecological Engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Korea.
authors.forename: Jung-Hwan
authors.initials: JH
authors.lastname: Kwon
authors.affiliation: Department of Environmental Engineering, Daegu University, 201 Daegudae-ro, Gyeongsan-si, Gyeongsanbuk-do, 38453, Korea. yshong@daegu.ac.kr.
authors.forename: Yongseok
authors.identifier: http://orcid.org/0000-0002-4746-7391
authors.initials: Y
authors.lastname: Hong
mesh_terms: D001554:Benzene / Q000032:analysis; D001555:Benzene Derivatives / Q000032:analysis / Q000737:chemistry*; D004129:Dimethylpolysiloxanes / Q000737:chemistry*; D004784:Environmental Monitoring / Q000379:methods*; D060587:Groundwater; D007700:Kinetics; D012117:Resins, Synthetic / Q000737:chemistry*; D012987:Soil / Q000737:chemistry; D014050:Toluene / Q000032:analysis; D055549:Volatile Organic Compounds / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*; D014992:Xylenes / Q000032:analysis
chemical_list: D001555:Benzene Derivatives; D004129:Dimethylpolysiloxanes; D012117:Resins, Synthetic; D012987:Soil; D055549:Volatile Organic Compounds; D014874:Water Pollutants, Chemical; D014992:Xylenes; D014050:Toluene; C013830:baysilon; C010102:delrin; D001554:Benzene; C004912:ethylbenzene
keywords: BTEX; Equilibrium partitioning; Groundwater pollution; Kinetics; Passive sampling; Polydimethylsiloxane (PDMS); Polyoxymethylene (POM); Soil pollution; Volatile organic compounds