RESUMO
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 with pyrene at neutral pH