Diffusion of phenolic compounds through polyethylene films

ABSTRACT: This paper presents experimental results of the diffusion of phenolic compounds through virgin and aged polyethylene (PE) films. The study considers five chlorophenols contaminants (4-chlorophenol, 2,4-dichlorophenol, 2,4,6-tricholophenol, 2,3,5,6-tetrachlorophenol, and pentachlorophenol) that are known to be toxic even at very low concentrations. The concentration dynamics in the source and receptor chambers of the diffusion cells is interpreted using the numerical code Pollute. For virgin PE film, partition coefficients ranged from 0.68 to 278, which corresponded to 4-chlorophenol and pentachlorophenol, respectively. Diffusion coefficients ranged from 1.0 × 10⁻¹⁴ to 2.7 × 10⁻¹³ m²/s, which corresponded to pentachlorophenol and 2,4-dichlorophenol, respectively. The study also looked at how the partition and diffusion coefficients were affected by the aqueous solubility, n-octanol–water partition coefficient, molecular diameter, and molecular weight. The trends observed in this study are similar to those found for diffusion of phenolic compounds through PE geomembranes. The results also revealed trends that differ from those previously reported for diffusion of volatile organic compounds (VOCs) through geomembranes. The existing empirical relationships for VOCs are not applicable except for calculating how the diffusion coefficient evolves as a function of solubility in water. Increasing the number of chlorine atoms on the phenolic nucleus causes an increase in the partition coefficient, which is tentatively attributed to the polarity of the molecules under study.