| Currently, polymer flooding and ASP flooding were widely used in our oilfield oil production process to enhance oil recovery, but the two technologies faced with new problems in the meantime: the amount of oilfield produced wastewater containing residual polymer and surfactant water increased year by year, so the viscosity of the sewage was increased and the emulsification of the sewage were enhanced. These problems needed to be solved by most oil fields in the future sewage treatment. In recent years, due to the notable features of Fenton’s reagent in the removal of the organic compounds in the wastewater, such as the lower operating costs, the simple process, easy to operate, environmentally friendly non-polluting, and attracted widespread attention.Oilfield wastewater was simulated in this thesis, the sewage containing polyacrylamide and sodium dodecyl sulfonate was chosen as the research object. The thesis discussed the optimum conditions of oxidative degradation of the simulation solution of surfactant sodium dodecyl sulfate and polyacrylamide by Fenton’s reagent respectively, and the oxidation degradation of coexistence of polyacrylamide and sodium dodecyl sulfate by Fenton reagent. All the conclusions were as follows:(1) The influence factors of oxidation degradation of polyacrylamide by Fenton’s reagent were investigated, the results showed that the concentration of H2O25.3mmol·L-1, the concentration of Fe2+1.44mmol-L-1, the range of pH value3-4, temperature of30℃, reaction time of15min. Under optimal oxidative degradation conditions, the removal rate of polyacrylamide reached87.61%, removal rate of CODCr reached82.60%. According to orthogonal experiment results the factors affecting weight order: H2O2concentration> Fe2+concentration> temperature> pH value. IR spectra of polyacrylamide oxidated by Fenton reagent showed that the side chain amide carboxyl was oxidated during the Fenton’s reagent reaction. The infrared spectra also showed partly polyacrylamide in the solution removed by flocculation and sedimentation. The UV spectrum showed that the polyacrylamide was oxidized into smaller organic molecules by Fenton’s reagent. The scanning electron micrographs showed that: after the Fenton reagent oxidation, polyacrylamide molecular beraked into small debris, or a low polymer or small molecule organics.(2)The optimal operating conditions of sodium dodecyl sulfate oxidation degradation by Fenton’s reagent were showed as following: concentration of Fe2+90mmg-L-1, the concentration of H2O210.6mmol-L"1, the range of pH values3-5reaction temperature of30℃, the reaction time of30min. Under the optimum conditions, the SDS removal efficiency reached82%.(3) The effect of the coexistence of polyacrylamide and sodium dodecyl sulfate on viscosity and surface tension were explored. The results showed that when concentration of polyacrylamide was certain, the surface tension of the solution was reduced with the increase of the concentration of surfactant, and viscosity of the solution changed little; when the concentration of sodium dodecyl sulfate was certain, the viscosity of the solution was increased with the increase of the concentration of the polyacrylamide, while the surface tension of the solution changed little.The optimal oxidative degradation conditions of complex systems degradated by Fenton reagent were:pH valve of3, the reaction time of20min, temperature of30℃, molar ratio of H2O2/Fe2+14. Under optimal conditions, the removal rate of complex solution CODcr could reach75%. The smooth and dense surface of complex solution sample became weaken when comparing with the scanning electron micrographs of the polyacrylamide solution, while intact surface of complex solution broke into many pieces, the surface with many small particles and became fragmented and uneven after oxidation by Fenton’s reagent. |
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