An oil displacement demulsifier and a preparation method thereof

Abstract

The application relates to an oil-displacing demulsifier and a preparation method thereof. First, magnetic carbon nanotubes are prepared by depositing ferric chloride hexahydrate and copper sulfate pentahydrate on the surface of carbon nanotubes; second, hyperbranched polymers with terminal double bonds are prepared; then, the two are mixed to obtain hyperbranched grafted magnetic carbon nanotubes; finally, allyl polyoxyethylene ether is continuously polymerized in situ to obtain the oil-displacing demulsifier. The oil-displacing demulsifier prepared by the application is suitable for oil-displacing demulsification treatment of coking wastewater in the early stage. The coking wastewater is complex in composition, contains little oil, but contains a lot of organic components. The polyether with multiple branched chains can form a net trapping effect in the water body, so that oil and water can be quickly gathered and separated in an emulsified state, and the oil removal rate can reach more than 97%. Meanwhile, the demulsifier has magnetism, can be recycled through magnetic separation, and the oil removal rate can still reach more than 92% after ten cycles of demulsification. The oil removal effect is good with a small amount of addition, and the coking wastewater treatment process is simplified.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment materials technology, specifically to an oil displacement and demulsifier and its preparation method. Background Technology

[0002] With rapid industrialization, wastewater discharge has become increasingly serious. As society places greater emphasis on environmental protection, the requirements for water treatment are also rising. Coking wastewater is a typical type of toxic and difficult-to-treat industrial organic wastewater. This wastewater contains large amounts of toxic and harmful substances, such as phenols, benzene, cyanide, and ammonia nitrogen. Its complex composition and high concentrations mean that excessive discharge of coking wastewater poses a significant threat to the environment.

[0003] Currently, water treatment processes mainly employ physical adsorption, flocculation sedimentation, and activated sludge methods. However, for complex coking wastewater, a single treatment method is insufficient to meet discharge standards. Therefore, there is a need to develop more efficient treatment agents for the advanced treatment of coking wastewater. Chinese patent CN106495241B discloses an oil displacement and demulsifier for coking wastewater, its preparation process, and its applications. This patent obtains a suitable formulation of the oil displacement and demulsifier through optimized screening. When used to treat coking wastewater, this oil displacement and demulsifier, after a single step of flocculation sedimentation, can reduce the oil content in the coking wastewater by 80%. However, this demulsifier is used in the treated wastewater, where the composition and content have already been significantly reduced. This oil displacement and demulsifier only provides further advanced treatment to the treated wastewater; however, the initial treatment of coking wastewater is the most challenging. Currently, there is still a lack of agents or methods for oil displacement and demulsification in the initial stage of coking wastewater treatment. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the present invention creatively proposes an oil displacement and demulsifier for coking wastewater. After oil displacement and demulsification, the coking wastewater is easier to flocculate and settle organic matter in the water, which can greatly improve the treatment efficiency of coking wastewater.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for preparing an oil displacement and demulsifier includes the following steps:

[0007] S1: Carbon nanotubes are ultrasonically dispersed in deionized water to form a dispersion, which is then mixed with ferric chloride hexahydrate and copper sulfate pentahydrate and stirred for 10-60 min. Then, 5-20 wt% ammonia water is added dropwise to adjust the pH to 7-8. The mixture is stirred and reacted at 90-100℃ for 2-10 h. After cooling, the mixture is filtered, and the solid product is washed alternately with ethanol and water and then dried. Finally, it is calcined at 400-500℃ in a nitrogen atmosphere for 1-4 h to obtain magnetic carbon nanotubes.

[0008] S2: Hyperbranched polymers were prepared by RAFT polymerization using xanthate with terminal double bonds as chain transfer agents, AIBN as initiator, and acrylamide as reactant monomer under a nitrogen atmosphere.

[0009] S3: Mix magnetic carbon nanotubes with amino-functionalized ionic liquid for later use. Dissolve hyperbranched polymer in DMF and undergo Michael addition reaction of amino-double bond under triethylamine catalysis to obtain hyperbranched grafted magnetic carbon nanotubes.

[0010] S4: The hyperbranched grafted magnetic carbon nanotubes were further dispersed in DMF, AIBN was added, nitrogen gas was introduced to remove air from the system, allyl polyoxyethylene ether was added, the temperature was raised to 70℃ and stirred for 12 h, after the reaction was completed, the solid was precipitated in ice-cold methanol, and dried to obtain the product.

[0011] Further, in step S1, the amounts of ferric chloride hexahydrate and copper sulfate pentahydrate are calculated according to n(Fe 3+ ):n(Cu 2 + The ratio of the total mass of the two nanotubes to the total mass of the carbon nanotubes is 2:1, and the ratio of their total mass to the mass of the carbon nanotubes is 5 to 10:1.

[0012] Further, in step S2, the structural formula of the xanthate ester with the terminal double bond is as follows: The molar ratio of RAFT chain transfer agent, initiator, and reactant monomer is 1:0.01:50 to 100.

[0013] Further, in step S3, the amino-functionalized ionic liquid is selected from one of 1-aminopropyl-3-methylimidazolium nitrate, 1-aminopropyl-3-methylimidazolium bromide, 1-aminoethyl-3-methylimidazolium nitrate, and 1-aminoethyl-3-methylimidazolium bromide.

[0014] Furthermore, in step S3, the mass ratio of magnetic carbon nanotubes, amino-functionalized ionic liquids, and hyperbranched grafted magnetic carbon nanotubes is 1:3:3 to 10.

[0015] Furthermore, in step S4, the molecular weight of the allyl polyoxyethylene ether ranges from 300 to 600, and its mass ratio to the hyperbranched grafted magnetic carbon nanotubes is 0.5 to 1:1.

[0016] The present invention further provides an oil displacement and demulsifier prepared by the preparation method described above.

[0017] This invention first uses multi-walled carbon nanotubes (CNTs) as a carrier, and utilizes the rich pore structure of CNTs to in-situ deposit and synthesize copper-doped magnetic nanomaterial CuFe2O4. This magnetic nanomaterial has been proven to have higher magnetic stability than Fe3O4. The obtained magnetic carbon nanotubes are mixed with an amino-functionalized ionic liquid. There is a π-π interaction between the ionic liquid and CNTs. Then, the amino groups in the ionic liquid undergo a Michael addition reaction with a hyperbranched polymer with terminal double bonds to coat the surface of the magnetic carbon nanotubes with an organic polymer, thereby improving the hydrophilicity of the material and effectively improving the dispersibility of carbon nanotubes in water and increasing the contact area. Finally, taking advantage of the characteristics of living radical polymerization, allyl polyoxyethylene ether (APEG) is further polymerized on the hyperbranched polymer to form an oil-displacing and demulsifying agent with a multi-branched polyether structure based on magnetic carbon nanotubes.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: The oil displacement and demulsifier prepared in this application is suitable for the early-stage oil displacement and demulsification treatment of coking wastewater. Coking wastewater has a complex composition, with a low oil content but a high amount of organic components. The polyether with a multi-branched structure in this application can form a net-catching effect in the water, which can make the oil and water quickly aggregate and separate in the emulsified state, and the oil removal rate can reach more than 97%. At the same time, the demulsifier is magnetic and can be recycled after magnetic separation. After ten cycles of demulsification-recovery-demulsification, the oil removal rate can still reach more than 92%. The addition amount is small and the oil removal effect is good, which simplifies the treatment process of coking wastewater. Detailed Implementation

[0019] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0021] Example 1:

[0022] S1: 10g of carbon nanotubes were ultrasonically dispersed in deionized water to form a dispersion, which was then mixed with 200ml of 0.8mol / L ferric chloride hexahydrate and 100ml of 0.8mol / L copper sulfate pentahydrate and stirred for 10-60min. Then, 5-20wt% ammonia was added dropwise to adjust the pH to 7-8. The mixture was stirred and reacted at 90-100℃ for 5h. After cooling, the mixture was filtered. The solid product was washed alternately with ethanol and water and then dried. Finally, it was calcined at 400℃ in a nitrogen atmosphere for 2h to obtain magnetic carbon nanotubes.

[0023] S2: Xanthate with terminal double bonds (Reference: Polym. Chem., 2011, 2, 2231-2238. Synthesis, hereinafter referred to as RAFT reagent) as chain transfer agent, AIBN as initiator, acrylamide as reactant monomer, molar ratio of 1:0.01:50, all substances were added to a Schlenk flask, tetrahydrofuran was added as solvent, nitrogen gas was introduced, and the reaction was carried out at 70℃ for 3-5 h under nitrogen atmosphere to obtain hyperbranched polymer;

[0024] S3: Mix 5g of magnetic carbon nanotubes with 15g of 1-aminopropyl-3-methylimidazolium nitrate for later use. Dissolve 15g of hyperbranched polymer in DMF, add 2g of triethylamine, and react at room temperature for 3h to obtain hyperbranched grafted magnetic carbon nanotubes.

[0025] S4: Continue to disperse hyperbranched grafted magnetic carbon nanotubes in DMF, add 0.5 times the amount of APEG300, add the catalytic amount of AIBN, purge nitrogen to remove air from the system, heat to 70℃ and stir for 12h. After the reaction is complete, precipitate solid in ice-cold methanol, dry and obtain the oil displacement demulsifier.

[0026] Example 2:

[0027] S1: 10g of carbon nanotubes were ultrasonically dispersed in deionized water to form a dispersion, which was then mixed with 200ml of 0.8mol / L ferric chloride hexahydrate and 100ml of 0.8mol / L copper sulfate pentahydrate and stirred for 10-60min. Then, 5-20wt% ammonia was added dropwise to adjust the pH to 7-8. The mixture was stirred and reacted at 90-100℃ for 5h. After cooling, the mixture was filtered. The solid product was washed alternately with ethanol and water and then dried. Finally, it was calcined at 400℃ in a nitrogen atmosphere for 2h to obtain magnetic carbon nanotubes.

[0028] S2:n(RAFT reagent: AIBN: acrylamide) = 1:0.01:60. All substances were added to a Schlenk flask, tetrahydrofuran was added as a solvent, nitrogen gas was introduced, and the mixture was heated to 70°C under a nitrogen atmosphere for 3-5 hours to obtain a hyperbranched polymer.

[0029] S3: Mix 5g of magnetic carbon nanotubes with 15g of 1-aminopropyl-3-methylimidazolium nitrate for later use. Dissolve 17g of hyperbranched polymer in DMF, add 2g of triethylamine, and react at room temperature for 3h to obtain hyperbranched grafted magnetic carbon nanotubes.

[0030] S4: Continue to disperse hyperbranched grafted magnetic carbon nanotubes in DMF, add 0.5 times the amount of APEG300, add the catalytic amount of AIBN, purge nitrogen to remove air from the system, heat to 70℃ and stir for 12h. After the reaction is complete, precipitate solid in ice-cold methanol, dry and obtain the oil displacement demulsifier.

[0031] Example 3:

[0032] S1: 10g of carbon nanotubes were ultrasonically dispersed in deionized water to form a dispersion, which was then mixed with 200ml of 0.8mol / L ferric chloride hexahydrate and 100ml of 0.8mol / L copper sulfate pentahydrate and stirred for 10-60min. Then, 5-20wt% ammonia was added dropwise to adjust the pH to 7-8. The mixture was stirred and reacted at 90-100℃ for 5h. After cooling, the mixture was filtered. The solid product was washed alternately with ethanol and water and then dried. Finally, it was calcined at 400℃ in a nitrogen atmosphere for 2h to obtain magnetic carbon nanotubes.

[0033] S2:n(RAFT reagent: AIBN: acrylamide) = 1:0.01:70. All the substances were added to a Schlenk flask, tetrahydrofuran was added as a solvent, nitrogen gas was introduced, and the mixture was heated to 70°C under a nitrogen atmosphere for 3-5 hours to obtain the hyperbranched polymer.

[0034] S3: Mix 5g of magnetic carbon nanotubes with 15g of 1-aminopropyl-3-methylimidazolium bromide for later use. Dissolve 20g of hyperbranched polymer in DMF, add 2g of triethylamine, and react at room temperature for 3h to obtain hyperbranched grafted magnetic carbon nanotubes.

[0035] S4: The hyperbranched grafted magnetic carbon nanotubes were further dispersed in DMF, 0.8 times the amount of APEG400 was added, and the amount of AIBN was added as a catalyst. Nitrogen gas was introduced to remove air from the system, and the temperature was raised to 70°C and stirred for 12 hours. After the reaction was completed, the solid was precipitated in ice-cold methanol. After drying, the oil displacement demulsifier was obtained.

[0036] Example 4:

[0037] S1: 10g of carbon nanotubes were ultrasonically dispersed in deionized water to form a dispersion, which was then mixed with 200ml of 0.8mol / L ferric chloride hexahydrate and 100ml of 0.8mol / L copper sulfate pentahydrate and stirred for 10-60min. Then, 5-20wt% ammonia was added dropwise to adjust the pH to 7-8. The mixture was stirred and reacted at 90-100℃ for 5h. After cooling, the mixture was filtered. The solid product was washed alternately with ethanol and water and then dried. Finally, it was calcined at 400℃ in a nitrogen atmosphere for 2h to obtain magnetic carbon nanotubes.

[0038] S2:n(RAFT reagent: AIBN: acrylamide) = 1:0.01:100. All substances were added to a Schlenk flask, tetrahydrofuran was added as a solvent, nitrogen gas was introduced, and the mixture was heated to 70°C under a nitrogen atmosphere for 3-5 hours to obtain a hyperbranched polymer.

[0039] S3: Mix 5g of magnetic carbon nanotubes with 15g of 1-aminopropyl-3-methylimidazolium nitrate for later use. Dissolve 15g of hyperbranched polymer in DMF, add 2g of triethylamine, and react at room temperature for 3h to obtain hyperbranched grafted magnetic carbon nanotubes.

[0040] S4: Continue to disperse hyperbranched grafted magnetic carbon nanotubes in DMF, add 0.5 times the amount of APEG300, add the catalytic amount of AIBN, purge nitrogen to remove air from the system, heat to 70℃ and stir for 12h. After the reaction is complete, precipitate solid in ice-cold methanol, dry and obtain the oil displacement demulsifier.

[0041] Example 5:

[0042] S1: 10g of carbon nanotubes were ultrasonically dispersed in deionized water to form a dispersion, which was then mixed with 300ml of 0.8mol / L ferric chloride hexahydrate and 150ml of 0.8mol / L copper sulfate pentahydrate and stirred for 10-60min. Then, 5-20wt% ammonia was added dropwise to adjust the pH to 7-8. The mixture was stirred and reacted at 90-100℃ for 5h. After cooling, the mixture was filtered. The solid product was washed alternately with ethanol and water and then dried. Finally, it was calcined at 400℃ in a nitrogen atmosphere for 2h to obtain magnetic carbon nanotubes.

[0043] S2:n(RAFT reagent: AIBN: acrylamide) = 1:0.01:70. All the substances were added to a Schlenk flask, tetrahydrofuran was added as a solvent, nitrogen gas was introduced, and the mixture was heated to 70°C under a nitrogen atmosphere for 3-5 hours to obtain the hyperbranched polymer.

[0044] S3: Mix 5g of magnetic carbon nanotubes with 15g of 1-aminopropyl-3-methylimidazolium bromide for later use. Dissolve 20g of hyperbranched polymer in DMF, add 2g of triethylamine, and react at room temperature for 3h to obtain hyperbranched grafted magnetic carbon nanotubes.

[0045] S4: The hyperbranched grafted magnetic carbon nanotubes were further dispersed in DMF, 0.8 times the amount of APEG400 was added, and the amount of AIBN was added as a catalyst. Nitrogen gas was introduced to remove air from the system, and the temperature was raised to 70°C and stirred for 12 hours. After the reaction was completed, the solid was precipitated in ice-cold methanol. After drying, the oil displacement demulsifier was obtained.

[0046] Comparative Example 1:

[0047] The carbon nanotubes were mixed with Fe3O4, and the remaining steps were the same as in Example 5.

[0048] Comparative Example 2:

[0049] 10g of carbon nanotubes were ultrasonically dispersed in deionized water to form a dispersion, which was then mixed with 300ml of 0.8mol / L ferric chloride hexahydrate and 150ml of 0.8mol / L copper sulfate pentahydrate and stirred for 10-60min. Then, 5-20wt% ammonia was added dropwise to adjust the pH to 7-8. The mixture was stirred and reacted at 90-100℃ for 5h. After cooling, the mixture was filtered, and the solid product was washed alternately with ethanol and water and dried. Finally, it was calcined at 400℃ in a nitrogen atmosphere for 2h to obtain magnetic carbon nanotubes.

[0050] Magnetic carbon nanotubes were mixed with allyl polyoxyethylene ether and used as an oil displacement and demulsifier.

[0051] Performance testing:

[0052] The oil displacement and demulsifier prepared above was used to treat coking wastewater discharged from a chemical plant. The coking wastewater was turbid and black, with a COD content of 7500 mg / L, an oil content of 85 mg / L, and ammonia nitrogen content, etc., which were not measured in this application. 500 mg of the above oil displacement and demulsifier was added to 1 L of coking wastewater, stirred evenly, and allowed to stand for 30-60 min. The appearance of the wastewater after demulsification was observed, and the oil removal rate was calculated and recorded in Table 1.

[0053] In addition, to test the magnetic properties of the oil displacement demulsifier, the wastewater after demulsification was separated from the oil displacement demulsifier under the action of a magnetic field. After being thoroughly washed with ethanol and water and dried, it was put back into new wastewater for the next round of demulsification experiment. This was repeated many times, and the oil removal rate after the tenth cycle was recorded in Table 2.

[0054] Table 1

[0055] COD (mg / L) Oil removal rate % Appearance Example 1 3950 97.8 The interface is well-layered, and the lower layer of water is clear. Example 2 3870 98.5 The interface is well-layered, and the lower layer of water is clear. Example 3 3660 99.2 The interface is well-layered, and the lower layer of water is clear. Example 4 4000 97.0 The interface is well-layered, and the lower layer of water is clear. Example 5 3680 99.1 The interface is well-layered, and the lower layer of water is clear. Comparative Example 1 4090 97.2 The interface is well-layered, and the lower layer of water is clear. Comparative Example 2 6550 65.4 The interface is not clearly layered, and the lower layer of water is turbid.

[0056] As shown in Table 1, the oil displacement demulsifier prepared in this application has a good demulsification effect, with an oil removal rate of over 97% and a COD removal rate of about 50%, thus reducing the burden on subsequent deep treatment. Comparing Comparative Example 1 and Comparative Example 2, the hyperbranched polyether structure coated on the carbon nanotubes has a better demulsification effect.

[0057] Based on Table 2, it is not difficult to see that the oil displacement and demulsifier prepared in this application has stable magnetism and can be recycled several times. After ten cycles of demulsification-recovery-demulsification, the oil removal rate can still reach more than 92%.

[0058] Table 2

[0059] Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Oil removal rate % 92.1 92.7 93.2 91.8 93.7 -- --

[0060] Due to the magnetic instability of the oil displacement and demulsifiers in Comparative Examples 1 and 2, they could not complete ten cycles. Comparative Example 1 was able to cycle 8 times, while Comparative Example 2 was only able to cycle 5 times.

[0061] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for preparing an oil displacement and demulsifier, characterized in that, Includes the following steps: S1: Disperse carbon nanotubes ultrasonically in deionized water to form a dispersion. Mix this dispersion with ferric chloride hexahydrate and copper sulfate pentahydrate and stir for 10-60 min. Then, add 5-20 wt% ammonia solution dropwise to adjust the pH to 7-8. Maintain a pH of 90-100. o The reaction was stirred at C for 2–10 h, cooled, filtered, and the solid product was washed alternately with ethanol and water, dried, and then dried at 400–500 °C. o Magnetic carbon nanotubes were obtained by calcination in a nitrogen atmosphere at C for 1-4 hours. S2: Hyperbranched polymers were prepared by RAFT polymerization using xanthate with terminal double bonds as chain transfer agents, AIBN as initiator, and acrylamide as reactant monomer under a nitrogen atmosphere. S3: Mix magnetic carbon nanotubes with amino-functionalized ionic liquid for later use. Dissolve hyperbranched polymer in DMF and undergo Michael addition reaction of amino-double bond under triethylamine catalysis to obtain hyperbranched grafted magnetic carbon nanotubes. S4: Continue to disperse the hyperbranched grafted magnetic carbon nanotubes in DMF, add AIBN, purge the system with nitrogen to remove air, add allyl polyoxyethylene ether, and heat to 70°C. o The reaction was stirred for 12 hours. After the reaction was complete, a solid precipitated in ice-cold methanol. After drying, the product was obtained. The structural formula of the xanthate with terminal double bonds is as follows: The molar ratio of RAFT chain transfer agent, initiator, and reactant monomer is 1:0.01:50 to 100. The amino-functionalized ionic liquid is selected from one of 1-aminopropyl-3-methylimidazolium nitrate, 1-aminopropyl-3-methylimidazolium bromide, 1-aminoethyl-3-methylimidazolium nitrate, and 1-aminoethyl-3-methylimidazolium bromide.

2. The method for preparing the oil displacement and demulsifier according to claim 1, characterized in that, In step S1, the amounts of ferric chloride hexahydrate and copper sulfate pentahydrate are determined according to n(Fe 3+ ):n(Cu 2+ The ratio of the total mass of the nanotubes to the total mass of the carbon nanotubes is 2:1, and the ratio of their total mass to the mass of the carbon nanotubes is 5 to 10:

1.

3. The method for preparing the oil displacement and demulsifier according to claim 1, characterized in that, In step S4, the molecular weight of allyl polyoxyethylene ether ranges from 300 to 600, and its mass ratio to hyperbranched grafted magnetic carbon nanotubes is 0.5 to 1:

1.

4. An oil displacement and demulsifier prepared by any one of claims 1-3.