摘要

Dissolved Fe(II) and humic acid (HA) were pre-impregnated into contaminated soil to catalyze hydrogen peroxide to remove crude oil (CO). The effects of parameters such as initial Fe(II), HA and H2O2 concentrations on the oxidation of total petroleum hydrocarbon (TPH) were investigated using response surface methodology based on Box-Behnken design. The rate of hydrogen peroxide decomposition is decreased by pre-impregnating with dissolved Fe(II) + HA compared with only pre-impregnated Fe(II) and modified Fenton (MF). Oxygen evolution is the predominant route of hydrogen peroxide decomposition at natural pH. Unlike O-2 evolution, the kinetics of hydroxyl radical (OH center dot) production are clearly uncoupled from H2O2 decay in these systems. The steady-state hydroxyl radical production rate is higher in the systems with pre-impregnated dissolved Fe(II) and HA, and more significance is the decrease in detectable TPH (70.84% removal efficiency) when soil is pre-impregnated with dissolved 25 mM Fe(II) + 0.7 mg/mL HA, and with the application of 700 mM H2O2, possibly due to hydrogen peroxide catalyzed by the iron of this complex (CO-HA-Fe(II)) producing hydroxyl radical in close proximity to the CO. Meanwhile, the removal efficiency of C-21-C-30 is up to 65.69%, which is 2.6times higher than that of the MF (25.52%).