Remediation of fuel oil contaminated soils by activated persulfate in the presence of MnO2

In this study, batch system experiments were carried out for evaluating the capability of persulfate (PS) to remediate fuel oil contaminated soils. Remediation was performed by spiking soil samples with fuel oil and then treating the mixture with sodium PS. Different controlling factors including pH (3, 6, and 9), PS concentrations (50-500 mmol/l), metal activators (ferrous sulfate, magnetite, and MnO2), and temperature (25, 40, and 60°C) were considered. Results proved that PS oxidation is effective in fuel oil degradation. The best PS : Fe2+ molar ratios were reported 400 : 2 and 250 : 1 for silty clay and loamy sand soil samples, respectively. Lower pH was more of interest in removal of fuel oil by PS oxidation. MnO2 improved fuel oil degradation when used together with metal activators. The results showed that when MnO2 was used together with ferrous sulfate and magnetite at acidic condition (pH = 3), the removal efficiencies were the best. Increasing temperature from 25 to 60°C improved the fuel oil degradation in the PS oxidation batch system. The results showed that activating PS by using ferrous sulfate along with MnO2 at acidic condition in 60°C could increase fuel oil degradation near to 58% in silty clay soil samples, while the degradation rate for loamy sand soil samples in similar conditions was 62%.