Title

Treatment of soil contaminated by fuel oil by using activated persulfate oxidation

Principal Investigator

Amir Hossein Mahvi

Abstract

Biological and chemical degradation of fuel oil is more difficult in comparison with lower ranges such as diesel and gasoline, which is due to their lower volatility, lower biodegradability, higher viscosity, and lower mobility. Many different advanced oxidation processes including enzymatic processes, peroxide oxidation, photochemical, and sonochemical process are efficient in degradation of organic pollutants from aqueous and soil media. Persulfate (PS) has been proved as a strong oxidant (E0 = 2.0 V). Furthermore, PS can be converted to sulfate radicals (SO4•-), which is a more powerful oxidant (E0= 2.6 V). The objective of this study was to evaluate the effects of PS which is activated by transition metals and minerals on treatment of fuel oil. In this study, batch system experiments were carried out for evaluating the ability of persulfate (PS) in remediation of fuel oil contaminated soils. Remediation was taken by spiking soil samples with fuel oil and then treating the mixture with sodium persulfate. Different controlling factors including pH (3, 6, and 9), persulfate concentrations (50-500 mM), metal activators such as ferrous, cobalt, and copper ions, minerals (pirite and ilminite), temperature (25, 40, and 60 ⁰C), and MnO2 as Co-oxidant were considered. Results proved that persulfate oxidation is effective in fuel oil degradation. The best PS: Fe2+, PS: Co2+, PS: Cu2+ molar ratios were reported 400:2 200:3, and 300:1, respectively, for silty clay soil sampl whilst it was 250:1, 150:1, and 200:2, respectively, for loamy sand soil sample. Lower pH was more of interest in removal of fuel oil by persulfate oxidation. MnO2 improved fuel oil degradation when used together with metal activators. The results showed that when MnO2 was used together with ferrous, cobalt, and copper ions and at acidic condition (pH=3), the removal efficiencies were the most. Increasing temperature from 25 to 60 ⁰C improved the TPHs degradation in persulfate oxidation batch system. The results showed that, using ferrous MnO2 along with ferrous, cobalt, and copper ions, could increase fuel oil removal upto 40, 44, and 46 %, respectively, in silty clay soil samples and 42, 47, and 37%, respectively for loamy sand soil samples

Year

2013