Diffusion coefficients of polychlorinated biphenyls and polycyclic aromatic hydrocarbons in polydimethylsiloxane and low‐density polyethylene polymers

Abstract

Diffusion coefficients (D) of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) were determined by film-stacking technique in low-density polyethylene (LDPE) and two types of polydimethylsiloxane (PDMS) (also known as silicone rubber, SR) with the trade names AlteSil TM and SilasticThe estimated values of D for PCBs and PAHs over a wide range of hydrophobicity were 2-2.5 orders of magnitude lower in LDPE than in SR polymers. Log D (m 2 s À1 ) of PCBs ranged from À10.1 to À10.9 for SRs and from À12.4 to À13.7 for LDPE. For PAHs these ranges were À9.8 to À11.4 for SRs and À11.9 to À13.7 for LDPE. Compared with the D values calculated in water, D were 1-2 and 3-4 orders of magnitude lower in SR and LDPE, respectively. For PAH molecules, D was lower than for PCBs with a similar molecular weight, probably because of their more rigid structure. The range of log D for PCBs in SR was only 0.5 log units (factor of 3.2) versus 1.2 log units (factor of 16) in LDPE. Although compound classes showed different relations, a linear relation of D with total surface area was the most universal. This relation may be used for prediction of D values in SR and LDPE polymers for other organic compounds.

An interlaboratory study on passive sampling of emerging water pollutants

“…does not limit the uptake rate. This can be confirmed by measuring the diffusion coefficients inside the sampler material [29]. Thus, it is necessary to know also diffusion coefficients of analytes and PRCs in the polymer used in partitioning PS.…”

Passive sampling for target and nontarget analyses of moderately polar and nonpolar substances in water

“…There may be some limitation to the diffusion of BDE-209 in the LDPE that may be more significant than in the silicone polymer. Different diffusion rates for chemicals in different polymer matrices have previously been observed [29], and different classes of chemicals might also have distinctly differing diffusion rates within the same polymer. A lower-than-expected sorption of BDE-209 to LDPE (K PE-W ) has been attributed to this large molecule having difficulty diffusing within the polymer matrix [30].…”

Low density polyethylene (LDPE) passive samplers for the investigation of polychlorinated biphenyl (PCB) point sources in rivers

“…Finally, R s is also increased with the use of a receiving phase which has high diffusion coefficients (D s ) for the investigated pollutants and a high K sw . D s of PCBs are higher in silicone than in LDPE (about 2.3-3.2 units of log) but LDPE is thinner (2 units of log if 0.05 mm thick LDPE from this study is compared with the 5 mm thick AlteSil silicone) (Rusina et al, 2010a). According to Smedes et al (2009), sampler-water partition coefficients of PCBs are of the same order of magnitude for LDPE and silicone (maximal difference of 0.5 units of log).…”