Research On The Remediation Of Soil Contaminated By Pahs Using Advanced Oxidation Processes

Advanced oxidation technology with its high efficiency,complete degradation of pollutants is widely used in the degradation of soil contaminants.Chlorine dioxide?ClO₂?catalytic oxidation of is a kind of advanced oxidation technology.The degradations of anthracene-contaminated soil using chlorine dioxide as oxidant and three kinds of catalysts prepared by different processes were studied in the thesis.The following innovative progresses were achieved in this work:1)CuO-montmorillonite was prepared using Na2CO3 precipitation method and its structure was determined by XRD,IR,TEM and EDS.ClO₂ catalytic oxidation degradation of anthracene-contaminated soil was studied in detail using CuO-montmorillonite as a catalyst.2)Fe₃O₄-CuO@ montmorillonite was prepared by coprecipitation method and used as catalyst for the degradation of anthracene in soil by ClO₂ oxidation process to reuse the catalyst conveniently by magnetic separation and avoid the secondary pollution to environment.Its structure was determined by XRD,IR,TEM and EDS.ClO₂ catalytic oxidation degradation of anthracene-contaminated soil was studied in using Fe₃O₄-CuO@ montmorillonite.The degradation effect of the catalyst was stable after 8 times recycle.3)Fe₃O₄@CuO composite material with core-shell structure was prepared using hydrothermal method and its structure was determined by XRD,IR,TEM and EDS.The results showed that CuO was coated on the surface of hollow Fe₃O₄ microspheres.Anthracene degradation rate decreased less after eight recycles,indicating good repeatability of Fe₃O₄@CuO.The chlorine dioxide?ClO₂?oxidative degradation of anthracene-contaminated soil was studied in detail using three kinds of catalysts.The operating parameters such as the ClO₂ concentration,catalyst dosage,reaction time and pH were evaluated.1)The optimal condition with CuO montmorillonite as catalyst was as follows: anthracene concentration 89.9mg/kg,ClO₂ concentration 1mol/kg,reaction time 30 min,catalyst dosage 1g/kg and pH 7.Anthracene degradation efficiency achieved 90%.2)The optimal condition with Fe₃O₄-CuO@ montmorillonite as catalyst was as follows: anthracene concentration 89.9 mg/Kg,ClO₂ concentration 1.0 mol/kg,reaction time 30 min,catalyst dosage 0.5g/kg and pH 7.Anthracene degradation efficiency achieved 95%.3)The optimal condition with Fe₃O₄-CuO@ montmorillonite as catalyst was as follows: anthracene concentration 89.9 mg/kg,ClO₂ concentration 0.7 mol/kg,reaction time 30 min,catalyst dosage 0.3 g/kg and pH 7.Anthracene degradation efficiency achieved 96%.The catalyst could be reused easily by magnetic separation and used at least 8 cycles without obvious loss of activity.The GC-MS was used to analyze the intermediate products of anthracene degradation and reaction kinetics were studied in this paper.The kinetic studies revealed that the ClO₂ catalytic oxidation degradation of anthracene-contaminated soil with the three kinds of catalysts followed pseudo-first-order kinetics with respect to ClO₂ concentration.