A Study on the Release of Oil from Oil-Contaminated Sediment Through Laboratory Experiments

The release of heavy oil from laboratory-contaminated sediments was studied in a series of kinetic and equilibrium experiments. The kinetic curves could be interpreted by a two-compartment first-order equation including rapid and slow release steps. The slow step was dominant and the rate constant was 3 orders of magnitude smaller than for the rapid step. Equilibrium experiments for the slow step revealed that the isotherms could be described by the Freundlich equation. The release of heavy oil was found to correlate with higher contamination level, larger particle size, lower salinity, and higher temperature. The effect of coexisting surfactant on the release was also investigated and the results showed that the presence of Tween-20 promoted the process. The oil release process was endothermic and the randomness at the solid-liquid interface increased during the desorption process. The values of activation energy and standard enthalpy change indicated that this process was a physical one.