Pankow absorption model

Particle-gas partitioning can be described by a variation of the Pankow absorption model, in which liquid-phase vapor pressure is replaced by the octanol-air partition coefficient as a fitting parameter (equations (22)-(25)). Section 10.3.4 states the advantages of doing so. Koa has been reported as a function of temperature for several PCB congeners, chlorobenzenes, PAHs, polychloronaphthalenes (PCNs), and p,p -DDT (Harner and Bidleman, 1996, 1998b Harner and Mackay, 1995 Komp and McLachlan, 1997). For others, Koa can be estimated from the ratio of the octanol-water partition coefficient to the Henry s law constant (H = Pa m3/ mol) (Finizio et al., 1997 Harner and Mackay, 1995 Simonich and Hites, 1995). 

The Pankow absorption model supposes that gaseous POPs partition into a liquid-like organic film on the aerosol. It uses P,s, the fraction of organic matter in the particle (fom), and the activity coefficient of the solute in the liquid film (yorJ. The latter is apt to vary substantially among different chemical classes of POPs. 

The present study was carried out to measure gaseous and particulate concentrations of PAHs and PCBs in Singapore urban air. The data were then apphed to make an assessment of the Junge-Pankow absorption model (Junge 1977 Pankow 1987), the octanol-air partitioning coefficient (Kqa) absorption model (Pankow... 

Koa and/om are easier to measure than the parameters used in Pankow absorption model (Hamer and Bidleman 1998 Faleoner and Hamer 2000). The slope is equal to 1 when plotting log Kp values against log Koa- However, various slope values have been reported in many studies (Table 3). 

Finizio et al. [7] provided an alternative interpretation of the Pankow absorption model [5] in terms of the octanol/air partition coefficient (Kqa, air/m octanol)... 

Pankow, J. F., An Absorption Model of Gas/Particle Partitioning of Organic Compounds in the Atmosphere, Atmos. Environ., 28, 185-188 (1994a). 

FIGURE 9.65 Observed percentages in the particle phase of PAHs (( ) N-E air ( ) S-W air), PCBs (( ) nonortho, ( ) monoortho, and multiortho PCBs, respectively), and ( ) PCNs in Chicago air compared to model predicted values, (a) Solid line is calculated with Junge-Pankow (J-P) adsorption model (Eq. (TT)). (b) Solid and dotted lines are calculated with absorption model for aerosols assumed to contain 10 and 20% organic matter (om), respectively (adapted from Harner and Bidleman, 1998). 

Pankow, J.F. 1994a. An absorption model of gas-particle partitioning in the atmosphere. Atmos. Environ. 21 185-188. 

Pankow J. F. An absorption model of the gas-aerosol partitioning involved in the formation of secondary organic aerosol. Atmos. Environ.l994b, Vol. 28, No. 2, 189-193. 

Similar to the partitioning in the water column, SVOCs can also partition through an absorption process in addition to physical adsorption onto the surface of particles. SVOCs would dissolve in the organic matter (OM) in the atmosphere, which exists both as primary (POA) and as secondary organic aerosols (SOA) (Lohmann and Lammel 2004). Kqa absorption model has been proposed by Pankow (1994) and Finizio et al. (1997). The octanol-air partitioning coefficient (Kqa) can be used to predict Kp with the assumption that the predominant distribution process is absorption (Harner and Bidleman 1998). The relationship between Kp and Kqa is... 

Comparison of Junge-Pankow Adsorption and Koa-based Absorption Models... 

Junge-Pankow model and Koa absorption model were found to simulate the data better than each other in different studies indicated by the coefficient of determination in Tables 2 and 3. In a Chicago study, Junge-Pankow model was found to fit the experimental PAH data better than Koa-based absorption model, while Koa-based absorption model better predicted the sorption of PCBs and PCDD/Fs, resolving the difference between multi-ortho and non-ortho PCBs (Hamer and Bidleman 1998). In a German study, Junge-Pankow model was found to be better than Koa-based absorption model for PCBs (Mandalakis and Stephanou 2007), although both models tend to underestimate the lower chlorinated PCBs. Another... 

Study by Lohmann et al. (2000) who examined partitioning of PCBs in the atmosphere of Manchester also drew the similar conclusion. On the contrary, Harner and Bidleman (1998) concluded that the Koa-based model is more suitable for PCBs compared to the Junge-Pankow model. Chen et al. found that Koa absorption model predicted better for most of PBDE congeners while Junge-Pankow model tended to overestimate the fractions of PBDEs in particle phase in a Chinese study (Chen et al. 2006). The prediction results may vary signihcantly with the assumption of different OM content and total surface area of particles (Shoeib et al. 2004 Chen et al. 2006 Cetin and Odabasi 2008). 

Pankow JF (1987) Review and comparative analysis of the theories on partitioning between the gas and aerosol particulate phases in the atmosphere. Atmos Environ 21 2275-2283 (1967) Pankow JF (1994) An absorption model of gas/particle partitioning of organic compounds in the... 

Pankow proposed two models of vapor/particle partitioning based on surface adsorption [4] and absorption [5]. Both models predict inverse relationships between Apa and the liquid-state saturation vapor pressure (Pl, Pa) that have the form [2] ... 

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