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Parameters affecting the desorption of hydrophobic organic chemicals from suspended sediments
Author(s) -
Borglin Sharon,
Wilke Amy,
Jepsen Rich,
Lick Wilbert
Publication year - 1996
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.5620151219
Subject(s) - desorption , partition coefficient , adsorption , hexachlorobenzene , chemistry , environmental chemistry , diffusion , particle (ecology) , total organic carbon , particle size , porosity , chromatography , organic chemistry , thermodynamics , pollutant , geology , physics , oceanography
Recent work has demonstrated that both the adsorption and desorption of hydrophobic organic chemicals to sediments and soils can be quite slow and that chemical equilibrium may not be a good approximation in many real situations. By means of long‒term batch experiments, this has been recently and clearly shown for the adsorption of hexachlorobenzene and three polychlorinated biphenyls to suspended sediments. In the present study, long‒term desorption experiments are performed with three hydrophobic organic chemicals (hexachlorobenzene and two polychlorinated biphenyls) and suspended sediments. Desorption times are on the order of a month to several years. It is shown that the desorption rates are dependent on the particle/floc size and density distributions, the type of water, the amount of organic carbon in the sediments, the time of adsorption before desorption, and the chemical partition coefficient. It is also shown that a simple chemical diffusion model with an effective diffusion coefficient dependent on the porosity of the particle/floc, the organic content of the sediments, and the chemical partition coefficient, along with proper consideration of particle/floc size and density distributions is sufficient to explain the experimental results.