The effect of volatilization on the mass flow of a non-aqueous pollutant liquid mixture in an inert porous medium: experiments with kerosene

Kerosene, an industrial petroleum product characterized by the presence of a large number of petroleum hydrocarbons (C₉-C₁₅), was selected as an example of a non-aqueous pollutant liquid (NAPL) mixture for our studies. Three inert materials (fine, medium and coarse sand) were used in the experiments and the initial amount of kerosene applied ranged from residual to saturated retention capacity. Volatilization in the air phase and saturated mass flow of kerosene in the three sands were studied in the laboratory under controlled conditions. The volatilization was the major physicochemical process affecting the fate of kerosene in the inert porous medium. During volatilization the liquid kerosene changed its composition by gradually losing its light components (C₉-C₁₃), and the viscosity of the remaining liquid kerosene increased. The increase in viscosity led to a decrease in the infiltration rate, for example, by about 20% when the viscosity increased from 1.3 × 10^?3 to 2.0 × 10^?3 Pa s. The relationship between the composition of the residual kerosene following volatilization and its mass flow in a sand illustrates the behaviour of non-aqueous pollutants in inert porous media.