Unsteady Mass-Transfer Modeling and Simulation of PBDEs in Air, Water, and Soil

Polybrominated diphenyl ethers as flame retardants prevent the branching mechanism of free radicals in gas phase during the combustion. Therefore, they are used in electric and electronical instruments. These supplies are entering the landfills after use. The existing flame retardants in these landfills enter the air, water and soil and pollute them. In this paper a mass-transfer model is developed with respect to the reactions and transfer processes of these chemicals in the various parts of environment. The curves of concentration versus time are also presented for three different compartment and four commercial PBDEs. The results show that concentrations of these chemicals are rather constant in the soil and so these pollutant chemicals are persistent in soil. Although concentrations of these pollutants in water have increasing trend, but the amount of concentration is lower than that of soil and it may be due to their hydrophobic structure. Incidentally, the concentration of these pollutants in air decreases with passing time.