| Sudden incidents has the characteristics of the frequency and the influence, and the related toxic chemical contaminants are dense usually, and there is a serious threat to not only environment security, but also health of human body. As an important organic chemical raw materials and products, aniline is carcinogenic, teratogenic and mutagenic. Solidification/stabilization is able to deal with contaminated soils efficiently, but there are some limitations when dealing with organic contaminated soils, so the research had combined oxidative degradation with solidification/stabilization to deal with the soils contaminated by high concentration aniline rapidly and efficiently.Effective solidification of aniline was researched by using cement as solidification agents, potassium persulfate as oxidant and activated carbon as adsorbent, and the characterization had been observed and analyzed to explore the proper dosage of different agents. The factors that influence the effect of degradation are explored, including reaction temperature, oxidant concentration, initial pH, and the results indicated that the aniline degradation rate increased with increase of temperature and the concentration of potassium persulfate. The optimal conditions for the degradation can be obtained at 40℃ for 150 min, and the amount of substance of potassium persulfate to aniline ratio was 100, so that the aniline degradation reaches 94.1% when the pH is 5～11.The applicability of potassium persulfate for aniline degradation in contaminated soils was also studied. The aniline degradation reached 98.6% when the temperature was 40 ℃, the amount of substance of potassium persulfate to aniline ratio was 100. And the reaction was carried out faster in soils than in water, and it was effective for a variety pH of soils.The advanced oxidation processes based on potassium persulfate, the activated carbon were combined with solidification/stabilization based on cement to deal with the soils contaminated by aniline. It was explored that the influence on the immobilization when the ratio of cement was different. The fixation rate was increased with the mass of cement, and 30%(the ratio of cement and soils, by weight) cement was the best addition. It can meet environmental requirements using only cement for the concentration of 50 mg/kg aniline in soils.Different initial concentration of aniline has impact on the immobilization. The fixation rate reduced with the increase of aniline concentration when the amount of cement kept constant. By adding activated carbon can reduce the content of aniline in the leaching solution. When the addition of activated carbon increased, the fixation rate was also increased. Adding 5.0% activated carbon and 30% cement (the ratio of activated carbon or cement and soils, by weight) into aniline concentration of 2000 mg/kg in soils.It needed adding potassium persulfate besides activated carbon and cement for high concentration of aniline to achieve the goal. Experiments with the soils contaminated by aniline concentration of 10000 mg/kg were carried out, when the dosage of cement was 30%, activated carbon was 5.0%, and the amount of substance of potassium persulfate to aniline ratio was 5, the fixation rate can reach 94.07%.The microstructure of solidified bodies was observed in the study by XRD and SEM. The results indicated that significant hydration reaction occurred in the solidified bodies, and the chemical compositions in the contaminated soils were almost in accordance with the clean soils under different ratios of additives. Although the aniline would affect the cement hydration reaction, and the particles in the solidified bodies were small and dispersed, but by adding activated carbon and potassium persulfate had reduced the impact, so that the surface of the solidified bodies was complete and compact after the completion of curing. |
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