Remediation of Anthracene-Contaminated Soil by ClO2 in the Presence of Magnetic Fe3O4-CuO@Montmorillonite as Catalyst

Abstract

Fe3O4-CuO@montmorillonite was prepared using coprecipitation method, and its structure was determined by XRD, IR, and transmission electron micrograph (TEM). Montmorillonite in Fe3O4-CuO@montmorillonite nanocomposite allowed the silicate layer of montmorillonite to behave as a barrier, which prevented the agglomeration and natural crystallization of Fe3O4 and CuO. Furthermore, the chlorine dioxide (ClO2) oxidative degradation of anthracene-contaminated soil was studied in detail using Fe3O4-CuO@montmorillonite as a magnetic heterogeneous catalyst. The operating parameters such as ClO2 concentration, catalyst dosage, reaction time, and pH were evaluated. Compared with the conventional ClO2 oxidation process without the catalyst, the ClO2 catalytic oxidation system could significantly enhance the degradation efficiency. Under the optimal condition (anthracene concentration 89.8 mg/kg, water soil mass ratio 3:1, initial pH 7, ClO2 concentration 1 mol/kg, catalyst dosage 1 g/kg, reaction time 30 min, and reaction temperature 25 °C), anthracene degradation efficiency achieved 96.2 %. The catalyst could be easily reused by magnetic separation and used at least 8 cycles without obvious loss of activity. The kinetic studies revealed that the ClO2 catalytic oxidation degradation of anthracene-contaminated soil with Fe3O4-CuO@montmorillonite as catalyst followed pseudo-first-order kinetics with respect to ClO2 concentration. Thus, this study showed potential application of ClO2 catalytic oxidation process in remediation of organic pollutant-contaminated soil.