The Oxidation Ability And The Viscosity Reduction Effect Of Catalytic Ozone Oxidation By Iron Based Catalysts To Ternary Produced Water

With the gradual application of the ASP technology for driving oil in many oilfields,the oil industry are producing more and more ternary produced water which is hard to be treated.However,the improvement of the current standards for the treatment of ternary produced water from oilfields has made it impossible for the existing treatment methods to achieve the standard of effluent quality after treatment.In this paper,two types of iron-based catalysts,powder and supported were prepared.The catalytic activities of iron-based catalysts in the catalytic oxidation of ozone were investigated by catalytically ozone-degrading three simple organic compounds: methylene blue,glucose,and potassium hydrogen phthalate respectively.Then,the effect of ozone-catalyzed oxidation of iron on the effluent viscosity of ternary flooding was studied in Daqing Oilfield.The experimental results of catalytic oxidation of methylene blue by iron-based catalyst catalyzed by ozonation showed when the concentration of methylene blue solution is 40.00mg/L and the volume of the solution is 500.0ml,that the optimal conditions for the degradation of methylene blue by catalytic oxidation of powdered iron-based catalysts are pH=11.00,the ozone flow rate is controlled to 40.0L/h,and powder catalyst dosage of 4.0 g/L.The time of catalytic degradation of methylene blue was the shortest,and the methylene blue solution was completely degraded after 25 minutes.The optimal conditions for the degradation of methylene blue by catalytic iron-catalyzed oxidation on a supported iron-based catalyst are pH=10.00,the ozone flow rate is controlled to 40.0 L/h,and supported catalyst dosage of 80.0 g/L.The time for the catalytic degradation of methylene blue is the shortest,and the methylene blue solution is completely degraded after 30 minutes.The experimental results of catalytic oxidation of methylene blue,glucose,and potassium hydrogen phthalate by iron-based catalysts showed that ozone oxidation alone can degrade methylene blue,but it cannot degrade potassium hydrogen phthalate and glucose.Through the study of the effect of iron-based catalyzed on the degradation of methylene blue,glucose,and potassium hydrogen phthalate by ozone oxidation,it is found that ozone oxidation can degrade methylene blue alone,but it cannot degrade potassium hydrogen phthalate and glucose;Powdered iron oxyhydroxide and supported iron oxyhydroxide have good effect on catalyzing the ozone degradation of methylene blue,potassium hydrogen phthalate,and glucose.Both have high catalytic activity and wide adaptability(catalytic effects in acidic,neutral,and alkaline environments).By investigating the effect of iron oxyhydroxide catalyzed by ozone oxidation on oilfield ternary produced water to reduce the viscosity,it is found that the optimum conditions for the catalytic ozone oxidation of powdered hydroxyl iron to reduce the viscosity of ternary produced water are as follows: when the ternary produced water is taken in 500.0ml,the ozone flow rate is controlled to 80.0L/h,the dosage of the powder type catalyst is 4.0g/L.Then the time required for the viscosity to fall to 1.80 mPa·s is the shortest which is only 30 minutes.The viscosity falling process needs 60 min,compared to the single ozone condition without catalyst.And the optimum conditions for the catalytic ozone oxidation of powdered iron oxyhydroxide to reduce the viscosity of ternary produced water are as follows: when the oil field ternary produced water is taken as 500 ml,the ozone flow rate is controlled to 80 L/h,and the powder catalyst dosage is for the 80.0g/L,the time required for the viscosity to drop to 1.80mPa·s is 50 minutes.The catalytic effect of powdered iron based catalyst on ozonation of oilfield ternary produced water is better than that of supported iron based catalyst.The presence of surfactants in the ternary produced water helps to increase the residence time of ozone in the reactor.At the same time,it can also increase the mass transfer of organic matter in the effluent from ozone and ternary produced water,thereby accelerating the viscosity reduction and increasing the viscosity reduction.rate.Using chlorine dioxide and ozone as oxidants to oxidize oilfield ternary produced water which is removed high concentrations of surfactant,the viscosity reduction effect is then studied.It is found that chlorine dioxide also has a good viscosity reduction effect.But under the same dosage,ozone has superiority on the viscosity rate and the viscosity reduction speed to chlorine dioxide.The reproducibility test results of the catalyst show that the powdered iron-based catalyst has a stable catalytic effect after catalyzing the methylene blue solution(pH=10.00)and ternary produced water of the oilfield.After catalytic degradation of methylene blue 20.00mg/L for 15 min,the removal rate was stable to 100%.The viscosities of the 500.0ml ternary effluent were all below 1.80 mPa·s for 30 min and the viscosity reduction rate fluctuates around 57%.When the supported iron-based catalyst catalyzes the methylene blue solution(pH=11.00),the supported catalyst catalyzes the degradation of methylene blue by ozone,dissolution occurs seriously and the catalytic effect gradually decreases.After 15 minutes,the removal rate of 20.00 mg/L methylene blue decreased from 95% to 86%,The supported catalyst has poor repeatability in the system when pH=11.00.