A method for treating waste oil sludge based on high voltage pulse electro-oxidation technology

Abstract

The invention discloses a method for treating waste oil sludge based on high-voltage pulse electro-oxidation technology, belonging to the technical field of petrochemical industry. The waste oil sludge to be treated is mixed with chabazite and modified silica microspheres, reacted for 0.5-10h under normal temperature and high-voltage pulse electric field conditions, and purified after oil and water phase separation; the surface of the modified silica microspheres is coated with a composite polyvinylidene fluoride / polymethyl methacrylate polymer layer and modified with carboxyl groups; the invention adds chabazite and modified silica microspheres to the waste oil sludge, and combines the high-voltage pulse electric field to achieve demulsification of the system. The treatment method can combine the demulsification and pulse electro-oxidation steps, thereby simplifying the treatment steps.

Description

Technical Field

[0001] The invention relates to the technical field of petrochemical industry, and in particular to a method for treating waste oil sludge based on high-voltage pulse electro-oxidation technology. Background Art

[0002] Oily sludge refers to sludge mixed with crude oil, various finished oils, residual oil and other heavy oils. Oily sludge does not exist inherently in nature, but is produced by crude oil extraction, oil field gathering and transportation process, oil refining process, oil-using industry or oil leakage, and is mixed with soil, water, etc. to form an oil-soil-water mixture. Oily sludge usually contains a large amount of difficult-to-degrade toxic and harmful substances, such as benzene, phenols, polychlorinated biphenyls, dioxins, anthracene, pyrene, etc., and is huge in volume. If it is discharged directly without treatment, it will not only occupy a large amount of arable land, but also produce foul-smelling gases, which will lead to serious groundwater pollution, serious damage to the natural ecology of food crops, trees, vegetation, etc., and will cause pollution to the surrounding soil, water and air; oily sludge is one of the main pollutants in the petroleum and petrochemical industries.

[0003] Oily sludge is generally a stable suspended emulsion system composed of water-in-oil (o / w), oil-in-water (w / o) and suspended solids. It has poor dehydration effect, high difficulty in treatment, and large differences in oil content. Generally, the oily sludge produced by oil fields, storage tanks, etc. has an oil content of 10%-50% and a water content of 40%-90%. Some of it has recycling and reuse value.

[0004] The ultimate goal of waste oil sludge treatment is to reduce the amount of waste oil, recycle it into resources and make it harmless. The commonly used treatment method for waste oil sludge is to separate oil from water by destroying the suspended emulsion system through solvent extraction and other methods, while reducing the viscosity of waste oil sludge, and then purify them separately. The oil phase is used to recover part of the oil content, and the water phase is used for comprehensive utilization after oxidation or biodegradation.

[0005] High-voltage pulse electro-oxidation technology is a new water treatment technology that integrates various advanced oxidation technologies. High-voltage pulse discharge technology uses an external electric field to inject energy into the water or the space above the water surface in a specific reactor to generate non-equilibrium plasma, triggering a series of complex physical and chemical processes to achieve the purpose of oxidation degradation; high-voltage pulse discharge technology has the advantages of low development cost, convenient treatment, and no secondary pollution.

[0006] When using high-voltage pulse electro-oxidation technology to treat waste oily sludge, it is usually necessary to first separate the oil and water in the system and then perform pulse electro-oxidation. The treatment steps are relatively complicated. At the same time, for some waste oily sludge with severe emulsification and stable state, the oil-water separation efficiency is low. Summary of the invention

[0007] In view of the above problems, the present invention provides a method for treating waste oil sludge based on high-voltage pulse electro-oxidation technology.

[0008] The purpose of the present invention is achieved by the following technical solutions:

[0009] A method for treating waste oil sludge based on high-voltage pulse electro-oxidation technology comprises the following steps:

[0010] The waste oil sludge to be treated is transferred into a treatment tank, chabazite and modified silica microspheres are added, and after being fully stirred and mixed, the mixture is reacted for 0.5-10 hours under normal temperature and high-voltage pulse electric field conditions, and then the mixture is allowed to stay in a phase separation tank for stratification, and the oil and water phases are separated and then purified separately;

[0011] The preparation method of the modified silica microspheres comprises the following steps:

[0012] (1) preparing nano-silica microspheres, keeping the nano-silica microspheres at 200-450° C. for 0.5-5 h, and cooling them for later use;

[0013] (2) adding polyvinylidene fluoride and polymethyl methacrylate to an organic solvent, stirring and dissolving them to prepare a polymer solution; dispersing the microspheres obtained in step (1) in the polymer solution, centrifuging the microspheres, and removing the solvent under reduced pressure for later use;

[0014] (3) adding the microspheres obtained in step (2) to an aqueous solution of 4-carboxylate benzene diazonium salt, stirring and reacting at 40-80° C. for 10-120 min, centrifuging and separating the microspheres, washing with deionized water and an alcohol solvent, and drying to obtain the microspheres.

[0015] In some preferred embodiments, the waste oil sludge to be treated is ground oil sludge, tank bottom oil sludge or shale oil sludge.

[0016] In some preferred embodiments, the mass ratio of the oil content of the waste oil sludge to the chabazite and the modified silica microspheres is 10:(0.5-3):(1-3.5).

[0017] In some preferred embodiments, the chabazite is a degassed product, and the degassing comprises the following steps:

[0018] The chabazite is soaked in a potassium chloride solution, refluxed at 60-70° C. for 12-24 hours, washed with deionized water and dried, and the dried chabazite is heated for heat treatment under a vacuum condition of no more than 10 Pa, and then cooled to obtain the method.

[0019] In some preferred embodiments, the silicon-aluminum ratio of the chabazite is 1.8-2.5; and the particle size of the chabazite is 60-200 mesh.

[0020] In some preferred embodiments, the heat treatment is: when the temperature is raised to 150°C, 250°C, and 350°C, the temperatures are kept for 1h, 1h, and 6h respectively, and the heating rate is 2-10°C / min.

[0021] In some preferred embodiments, the pulse amplitude of the high-voltage pulse electric field is 5-15 kV, the pulse frequency is 100-1500 Hz, the pulse width is 10-100 μs, and the distance between the two electrodes of the high-voltage pulse electric field is 1-50 cm.

[0022] In some preferred embodiments, the mass ratio of the polyvinylidene fluoride and the polymethyl methacrylate in step (2) is (2.5-9):1, and the concentration of the polymer in the polymer solution is 14-20wt%.

[0023] In some preferred embodiments, the organic solvent in step (2) is a mixed solvent of acetone and N,N-dimethylformamide, and the mixed volume ratio thereof is (2.5-4):1.

[0024] In some preferred embodiments, the 4-carboxylic acid benzene diazonium salt in step (3) is toluenesulfonate of 4-carboxylic acid benzene diazonium, and the concentration of its aqueous solution is 1.5-3 g / L.

[0025] The beneficial effects of the present invention are:

[0026] In view of the problem that demulsification is required before treating waste oil sludge with high-voltage pulse electro-oxidation technology, and the treatment steps are relatively complicated, the present invention provides a waste oil sludge treatment method based on high-voltage pulse electro-oxidation technology. The treatment method can combine the demulsification and pulse electro-oxidation steps, thereby simplifying the treatment steps. Specifically, the present invention adds chabazite and modified silica microspheres to the waste oil sludge, and combines high-voltage pulse electric field to achieve demulsification of the system. Chabazite has unique adsorption and ion exchange properties. The interior of chabazite has pores with uniform pore size and a large number of holes, so that the interior of chabazite has a particularly large surface area. The cations inside the chabazite have a certain fluidity. When the chabazite is immersed in a liquid with metal cations When the chabazite is placed in a salt solution of an ion, the original cations in the chabazite can be replaced, and the chabazite can change its internal pore size as well as the electric field and surface acidity inside the crystal, thereby changing its adsorption. The present invention utilizes a high-voltage pulse electric field to induce a reversible expansion and adsorption of the chabazite skeleton, thereby increasing the instability of the emulsified system and promoting water-oil phase transfer. Furthermore, ion exchange and degassing treatment can increase the stability of the zeolite skeleton. The surface of the modified silica microspheres is coated with a composite polyvinylidene fluoride / polymethyl methacrylate polymer layer and modified with carboxyl groups. The excellent dielectric properties of polyvinylidene fluoride / polymethyl methacrylate are utilized, and the change in surface energy under the stimulation of a changing electric field can promote water-oil phase transfer in the emulsion. DETAILED DESCRIPTION

[0027] The present invention is further described in conjunction with the following examples.

[0028] The waste oil sludge described in the embodiment of the present invention is tank bottom oil sludge from Aohan Pagoda Oil Shale Co., Ltd., with a water content of 23.8%, an oil content of 48.17%, a low calorific value of 18750 kJ / kg, and an ash content of 12.31%.

[0029] Example 1

[0030] A method for treating waste oil sludge based on high-voltage pulse electro-oxidation technology comprises the following steps:

[0031] The waste oil sludge to be treated is transferred into a treatment tank, chabazite and modified silica microspheres are added, and after being fully stirred and mixed, the mixture is reacted for 4 hours under normal temperature and high-voltage pulse electric field conditions, and then placed in a phase separation tank for stratification. After the oil and water phases are separated, they are purified separately. The finished oil is obtained after the oil layer is dried, and the oil sludge residue is obtained after the water layer is dehydrated and dried;

[0032] The mass ratio of the oil content of the waste oil sludge to the chabazite and the modified silica microspheres is 10:1.5:2.5;

[0033] The chabazite has a silicon-aluminum ratio of 2.2 and a particle size of 100 mesh;

[0034] The preparation method of the modified silica microspheres comprises the following steps:

[0035] (1) keeping the nano-silica microspheres at 350° C. for 2 hours, cooling them for standby use, and the particle size of the nano-silica microspheres is 100-1000 nm;

[0036] (2) adding polyvinylidene fluoride and polymethyl methacrylate to a mixed solvent of acetone and N,N-dimethylformamide (v / v=3 / 1), stirring and dissolving to prepare a polymer solution; dispersing the microspheres obtained in step (1) in the polymer solution, centrifuging the microspheres, and removing the solvent under reduced pressure for later use; the mass ratio of the polyvinylidene fluoride to the polymethyl methacrylate is 4:1, and the concentration of the polymer in the polymer solution is 15wt%;

[0037] (3) adding the microspheres obtained in step (2) to an aqueous solution of 4-carboxybenzenediazide toluenesulfonate (concentration 1.5 g / L), stirring and reacting at 40-80° C. for 10-120 min, centrifuging and separating the microspheres, washing with deionized water and an alcohol solvent, and drying to obtain the microspheres;

[0038] The pulse amplitude of the high-voltage pulse electric field is 10 kV, the pulse frequency is 500 Hz, the pulse width is 100 μs, the pulse duty cycle is 0.5, and the distance between the two electrodes of the high-voltage pulse electric field is 10 cm.

[0039] The average oil recovery rate of the oily sludge in this example (parallel 3 times) is 76.1%, and the TOC removal rate is 48.30%.

[0040] Example 2

[0041] A method for treating waste oil sludge based on high-voltage pulse electro-oxidation technology comprises the following steps:

[0042] The waste oil sludge to be treated is transferred into a treatment tank, chabazite and modified silica microspheres are added, and after being fully stirred and mixed, the mixture is reacted for 4 hours under normal temperature and high-voltage pulse electric field conditions, and then placed in a phase separation tank for stratification. After the oil and water phases are separated, they are purified separately. The finished oil is obtained after the oil layer is dried, and the oil sludge residue is obtained after the water layer is dehydrated and dried;

[0043] The mass ratio of the oil content of the waste oil sludge to the chabazite and the modified silica microspheres is 10:1.5:2.5;

[0044] The chabazite is a degassed product, and the degassing comprises the following steps:

[0045] The chabazite was immersed in a 1 mol / L potassium chloride solution, refluxed at 65°C for 14 hours, washed with deionized water and dried, and the dried chabazite was heated for heat treatment under a vacuum condition of no more than 10 Pa, with a heating rate of 5°C / min, and kept warm for 1h, 1h, and 6h when the temperature was raised to 150°C, 250°C, and 350°C, respectively, and then cooled to obtain the chabazite; the silicon-aluminum ratio of the chabazite was 2.2, and the particle size was 100 mesh;

[0046] The preparation method of the modified silica microspheres comprises the following steps:

[0047] (1) keeping the nano-silica microspheres at 350° C. for 2 hours, cooling them for standby use, wherein the particle size of the nano-silica microspheres is 100-1000 nm;

[0048] (2) adding polyvinylidene fluoride and polymethyl methacrylate to a mixed solvent of acetone and N,N-dimethylformamide (v / v=3 / 1), stirring and dissolving to prepare a polymer solution; dispersing the microspheres obtained in step (1) in the polymer solution, centrifuging the microspheres, and removing the solvent under reduced pressure for later use; the mass ratio of the polyvinylidene fluoride to the polymethyl methacrylate is 4:1, and the concentration of the polymer in the polymer solution is 15wt%;

[0049] (3) adding the microspheres obtained in step (2) to an aqueous solution of 4-carboxybenzenediazide toluenesulfonate (concentration 1.5 g / L), stirring and reacting at 40-80° C. for 10-120 min, centrifuging and separating the microspheres, washing with deionized water and an alcohol solvent, and drying to obtain the microspheres;

[0050] The pulse amplitude of the high-voltage pulse electric field is 10 kV, the pulse frequency is 500 Hz, the pulse width is 100 μs, the pulse duty cycle is 0.5, and the distance between the two electrodes of the high-voltage pulse electric field is 10 cm.

[0051] The average oil recovery rate of the oily sludge in this example (three times in parallel) is 78.4%, and the TOC removal rate is 47.82%.

[0052] Example 3

[0053] A method for treating waste oil sludge based on high-voltage pulse electro-oxidation technology comprises the following steps:

[0054] The waste oil sludge to be treated is transferred into a treatment tank, chabazite and silica microspheres are added, and after being fully stirred and mixed, the mixture is reacted for 4 hours under normal temperature and high-voltage pulse electric field conditions, and then placed in a phase separation tank for stratification. After the oil and water phases are separated, they are purified separately. The finished oil is obtained after the oil layer is dried, and the oil sludge residue is obtained after the water layer is dehydrated and dried;

[0055] The mass ratio of the oil content of the waste oil sludge to the chabazite and the modified silica microspheres is 10:1.5:2.5;

[0056] The chabazite has a silicon-aluminum ratio of 2.2 and a particle size of 100 mesh;

[0057] The silica microspheres are heat treated (350°C for 2 hours) and have a particle size of 100-1000 nm;

[0058] The pulse amplitude of the high-voltage pulse electric field is 10 kV, the pulse frequency is 500 Hz, the pulse width is 100 μs, the pulse duty cycle is 0.5, and the distance between the two electrodes of the high-voltage pulse electric field is 10 cm.

[0059] The average oil recovery rate of the oily sludge in this example (three times in parallel) is 41.3%, and the TOC removal rate is 48.14%.

[0060] Example 4

[0061] A method for treating waste oil sludge based on high-voltage pulse electro-oxidation technology comprises the following steps:

[0062] The waste oil sludge to be treated is transferred into a treatment tank, chabazite is added, and after being fully stirred and mixed, it is reacted for 4 hours under normal temperature and high-voltage pulse electric field conditions, and then placed in a phase separation tank for stratification;

[0063] Wherein, the mass ratio of the oil content of the waste oil sludge to the chabazite is 10:1.5;

[0064] The chabazite has a silicon-aluminum ratio of 2.2 and a particle size of 100 mesh;

[0065] The pulse amplitude of the high-voltage pulse electric field is 10 kV, the pulse frequency is 500 Hz, the pulse width is 100 μs, the pulse duty cycle is 0.5, and the distance between the two electrodes of the high-voltage pulse electric field is 10 cm.

[0066] The average oil recovery rate of the oily sludge in this example (three times in parallel) is 42.6%, and the TOC removal rate is 48.06%.

[0067] Example 5

[0068] A method for treating waste oil sludge based on high-voltage pulse electro-oxidation technology comprises the following steps:

[0069] The waste oil sludge to be treated is transferred into a treatment tank, modified silica microspheres are added, and after being fully stirred and mixed, the mixture is reacted for 4 hours under normal temperature and high-voltage pulse electric field conditions, and then placed in a phase separation tank for stratification;

[0070] Wherein, the mass ratio of the oil content of the waste oil sludge to the modified silica microspheres is 10:2.5;

[0071] The preparation method of the modified silica microspheres comprises the following steps:

[0072] (1) keeping the nano-silica microspheres at 350° C. for 2 hours, cooling them for standby use, wherein the particle size of the nano-silica microspheres is 100-1000 nm;

[0073] (2) adding polyvinylidene fluoride and polymethyl methacrylate to a mixed solvent of acetone and N,N-dimethylformamide (v / v=3 / 1), stirring and dissolving to prepare a polymer solution; dispersing the microspheres obtained in step (1) in the polymer solution, centrifuging the microspheres, and removing the solvent under reduced pressure for later use; the mass ratio of the polyvinylidene fluoride to the polymethyl methacrylate is 4:1, and the concentration of the polymer in the polymer solution is 15wt%;

[0074] (3) adding the microspheres obtained in step (2) to an aqueous solution of 4-carboxybenzenediazide toluenesulfonate (concentration 1.5 g / L), stirring and reacting at 40-80° C. for 10-120 min, centrifuging and separating the microspheres, washing with deionized water and an alcohol solvent, and drying to obtain the microspheres;

[0075] The pulse amplitude of the high-voltage pulse electric field is 10 kV, the pulse frequency is 500 Hz, the pulse width is 100 μs, the pulse duty cycle is 0.5, and the distance between the two electrodes of the high-voltage pulse electric field is 10 cm.

[0076] The average oil recovery rate of the oily sludge in this example (parallel 3 times) is 50.8%, and the TOC removal rate is 47.91%.

[0077] Comparison Example

[0078] A method for treating waste oil sludge based on high-voltage pulse electro-oxidation technology comprises the following steps:

[0079] The waste oil sludge to be treated is transferred into the treatment tank, fully stirred and homogenized, reacted for 4 hours under normal temperature and high voltage pulse electric field conditions, and then stayed in the phase separation tank for stratification;

[0080] The pulse amplitude of the high-voltage pulse electric field is 10 kV, the pulse frequency is 500 Hz, the pulse width is 100 μs, the pulse duty cycle is 0.5, and the distance between the two electrodes of the high-voltage pulse electric field is 10 cm.

[0081] The average oil recovery rate of the oily sludge described in this comparative example (parallel 3 times) was 19.5%, and the TOC removal rate was 49.62%.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for treating waste oil sludge based on high-voltage pulse electro-oxidation technology, characterized in that: The following steps are involved: The waste oil sludge to be treated is transferred into a treatment tank, chabazite and modified silica microspheres are added, and after being fully stirred and mixed, the mixture is reacted for 0.5-10 hours under normal temperature and high-voltage pulse electric field conditions, and then the mixture is allowed to stay in a phase separation tank for stratification, and the oil and water phases are separated and then purified separately; The preparation method of the modified silica microspheres comprises the following steps: (1) preparing nano-silica microspheres, keeping the nano-silica microspheres at 200-450° C. for 0.5-5 h, and cooling them for later use; (2) adding polyvinylidene fluoride and polymethyl methacrylate to an organic solvent, stirring and dissolving them to prepare a polymer solution; dispersing the microspheres obtained in step (1) in the polymer solution, centrifuging the microspheres, and removing the solvent under reduced pressure for later use; (3) adding the microspheres obtained in step (2) to an aqueous solution of 4-carboxylate benzene diazonium salt, stirring and reacting at 40-80° C. for 10-120 min, centrifuging and separating the microspheres, washing with deionized water and an alcohol solvent, and drying to obtain the microspheres.

2. The method for treating waste oil sludge based on high voltage pulse electro-oxidation technology according to claim 1, characterized in that: The waste oil sludge to be treated is ground oil sludge, tank bottom oil sludge or shale oil sludge.

3. The method for treating waste oil sludge based on high voltage pulse electro-oxidation technology according to claim 1, characterized in that: The mass ratio of the oil content of the waste oil sludge to the chabazite and the modified silica microspheres is 10:(0.5-3):(1-3.5).

4. The method for treating waste oil sludge based on high voltage pulse electro-oxidation technology according to claim 1, characterized in that: The chabazite is a degassed product, and the degassing comprises the following steps: The chabazite is soaked in a potassium chloride solution, refluxed at 60-70° C. for 12-24 hours, washed with deionized water and dried, and the dried chabazite is heated for heat treatment under a vacuum condition of no more than 10 Pa, and then cooled to obtain the method.

5. The method for treating waste oil sludge based on high voltage pulse electro-oxidation technology according to claim 4 is characterized in that: The silicon-aluminum ratio of the chabazite is 1.8-2.5; the particle size of the chabazite is 60-200 meshes.

6. The method for treating waste oil sludge based on high voltage pulse electro-oxidation technology according to claim 4, characterized in that: The heat treatment is as follows: when the temperature is raised to 150° C., 250° C. and 350° C., the temperature is kept for 1 h, 1 h and 6 h respectively, and the heating rate is 2-10° C. / min.

7. The method for treating waste oil sludge based on high voltage pulse electro-oxidation technology according to claim 1, characterized in that: The pulse amplitude of the high-voltage pulse electric field is 5-15 kV, the pulse frequency is 100-1500 Hz, the pulse width is 10-100 μs, and the distance between the two electrodes of the high-voltage pulse electric field is 1-50 cm.

8. The method for treating waste oil sludge based on high voltage pulse electro-oxidation technology according to claim 1, characterized in that: In step (2), the mass ratio of the polyvinylidene fluoride to the polymethyl methacrylate is (2.5-9):1, and the concentration of the polymer in the polymer solution is 14-20wt%.

9. The method for treating waste oil sludge based on high voltage pulse electro-oxidation technology according to claim 1, characterized in that: The organic solvent in step (2) is a mixed solvent of acetone and N,N-dimethylformamide, and the mixed volume ratio is (2.5-4):

1.

10. The method for treating waste oil sludge based on high voltage pulse electro-oxidation technology according to claim 1, characterized in that: The 4-carboxylic acid benzene diazonium salt in step (3) is toluenesulfonate of 4-carboxylic acid benzene diazonium, and the concentration of its aqueous solution is 1.5-3 g / L.