Study On Oxidation Treatment Of Phenol Contaminted Soil Using Potassium Ferrate

Chemical leaking accidents which could cause serious point source soil contamination happened frequently in the storage, transportation and usage of hazardous chemicals. These chemicals are extremely detrimental to ecological environment and human health, and they would chronically exist in the soil and strongly bound to the soil matrix if they can not be eliminated immediately. To eliminate the negative impacts of these accidents, rapid on-site disposal of the contaminated soil would be highly necessary.In this paper, phenol was selected as the target contaminant and the simulant phenol contaminated soil was treated with Potassium Ferrate Oxidation Method. Through the study of the influencing factors of phenol degradation efficiency, optimum operating conditions were identified. Automatic control of the whole treatment process was achieved. The final products and intermediates of the reaction were also identified by HPLC method and the reaction pathway of phenol degradation by potassium ferrate was concluded.Through single-factor experiments, the optimum operating conditions were identified as follows:soil-water ratio of the slurry 1:1-1:4; phenol-potassium ferrate molar ratio 7.5:1; initial system pH 7.0～9.0 (adjusted by 2% sulfuric acid); moderate mixing; potassium ferrate was added into the reactor in batches, dosing amount 0.15 g/batch. Under optimum conditions, the degradation efficiency of phenol reached up to 95% and the whole reaction process was done in 10 min. After each round of reaction, the supernatant of the slurry can be reused in the next round after its pH was adjusted to neutral by 2% sulfuric acid. To eliminate the bad impacts of the residual oxidant, ferrous sulfate can be added into treated soil to neutralize excessive oxidant. Based on the fact that system pH kept increasing during the reaction process, automatic control of the dosing of potassium ferrate was achieved through the monitoring of system pH value. The process flow of potassium ferrate treating point source phenol contaminated soil was further designed to establish an integrated method. Based on HPLC testing results and the intermediate product, the reaction pathway was concluded as follows: The research results of this paper can be used as a reference for practical applications.