Modified Fenton oxidation of pyrene in contaminated soils using iron nano oxides

Problems related to conventional Fenton oxidation، including neccesity of having a low pH and production of considerable amounts of sludge، have prompted researchers to consider chelating agents to improve the pH operating range and iron nano-oxide particles to reduce excess sludge. The main objective of this study was to remove pyrene from contaminated soils by a modified Fenton oxidation method at neutral pH.

Experiments were conducted using various concentrations of H2O2 (0-500 mM)، iron nano-oxides (0-60 mM)، reaction times (0. 5-24 hours) and several chelating agents، namely، sodium pyrophosphate، ethylene diamine tetra-acetic acid، sodium citrate، fulvic and humic acids، to eliminate pyrene from soil (concentrations of 100-500 mg/kg).

The efficiency of removal of pyrene at an initial concentration of 100 mg/kg was 99 % at the following reaction conditions: H2O2 and iron nano-oxide concentrations of 300 mM and 30 mM، respectively; pH=3; and a reaction time of 6 hours. The initial pyrene concentration of 100 mg/kg decreased to 7 mg/kg at optimum conditions using sodium pyrophosphate as the chelating agent at pH 7.

The modified Fenton oxidation method، using iron nano-oxide at optimum conditions as defined in this research، is an efficient alternative for chemical remediation or pre-treatment of soils contaminated wih pyrene at neutral pH.