Demulsifier for oily wastewater treatment and preparation method thereof

Abstract

The present invention belongs to the field of water treatment technology, specifically relating to a demulsifier for treating oily wastewater and its preparation method. The preparation method comprises firstly reacting sodium laurylaminopropionate with propylene oxide under conditions of high temperature and high pressure in the presence of a catalyst to produce an intercalated propyl ether intermediate; secondly, adding a first ethylene oxide to produce an intercalated ether intermediate; and finally, adding a second ethylene oxide in an acidic environment under conditions of high temperature and high pressure to produce an intercalated ether intermediate. The demulsifier of the present invention features a simple synthesis process and a high demulsification rate. At a concentration of 15 mg / L, the oil removal rate reaches over 98%.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment, and particularly relates to a demulsifier for treating oily wastewater and a preparation method thereof. Background Art

[0002] Since oil fields entered their high-water-cut development phase, ASP flooding technology has been implemented to enhance crude oil recovery, significantly improving it. However, the oil-displacing agents, such as alkali, surfactants, and polymers, also severely emulsify oilfield wastewater. Crude oil is mostly recovered as an emulsion, dramatically increasing the oil content in the produced water. This emulsion not only creates a series of difficulties for crude oil extraction but also negatively impacts oil and gas gathering, processing, and refining. It also wastes environmental resources, necessitating demulsification of the wastewater to recover the crude oil.

[0003] The process of separating emulsified water from crude oil is called demulsification. Methods for crude oil demulsification include electrolysis, wetting coalescence dehydration, and chemical demulsification. Chemical demulsification is a commonly used method for crude oil dehydration. Demulsifiers are primarily surfactants and are added to the crude oil emulsion to disrupt the emulsion and separate the oil and water into two layers.

[0004] There are many types of conventional demulsifiers, mainly cationic organic polymer coagulants (such as polydimethyldiallyl ammonium chloride, epichlorohydrin-fatty amine, etc.) and non-ionic organic polymer coagulants (such as ethylene oxide-propylene oxide series). These agents generally have a high oil content in the lower layer of water after demulsification, which increases the cost and difficulty of the subsequent sewage treatment system.

[0005] CN101357783A discloses a method for preparing a highly efficient emulsified wastewater demulsifier, characterized by comprising the following steps: first, slowly adding an aqueous solution of a ferric salt containing 9-15% Fe2O3 to an aqueous solution of sodium silicate containing 0.8-2.4% silicon in a weight ratio of 10:1 to the aqueous solution of the ferric salt, adjusting the pH to 3-5, and reacting at 40-70°C for 2-4 hours to obtain an iron-silicon polymer; second, adding an aqueous solution of a ferric aluminum salt containing 10-14% Al2O3 (the same weight as the aqueous solution of the ferric salt) to the iron-silicon polymer synthesized in the first step under stirring, adjusting the pH to 2-3.5, and polymerizing at 40-70°C for 2-4 hours to obtain the demulsifier. The emulsified wastewater demulsifier obtained by the present invention has coagulation and purification functions while breaking the emulsion, is easy to operate, and has good environmental performance. However, when treating wastewater with this degreasing agent, the agent requires a large amount of reagent, produces a large amount of scum, causing secondary pollution, and is difficult to guarantee degreasing effectiveness.

[0006] CN106565007 discloses a deoiling agent for produced water from ASP flooding. The deoiling agent is formed by reacting 2,5-pyridinediamine with formaldehyde and formic acid to form an intermediate, which is then reacted with sodium chlorododecanoate to form a zwitterionic deoiling agent. The molar ratio of 2,5-pyridinediamine, formaldehyde, formic acid, and sodium chlorododecanoate is 1:2.5-6:2.5-5.5:0.8-2.5, preferably 1:3:3:1.5. The deoiling agent of the present invention has the characteristics of simple preparation, strong adaptability, low cost, strong salt resistance and good oil removal effect, with a salt tolerance of 2.3×10 4 mg / L, achieving an oil removal rate of over 97% in produced water from ASP flooding. Furthermore, the recovered oil produced by separation does not affect subsequent crude oil dehydration. Therefore, the present invention is widely applicable to oil removal processes for produced water from ASP flooding. However, the product of this invention contains pyridine monomer, which is highly toxic and can easily cause environmental pollution. Summary of the Invention

[0007] Aiming at the deficiencies of the current prior art, the present invention provides a demulsifier for treating oily wastewater and a preparation method thereof. The demulsifier has the characteristics of simple synthesis process and high demulsification rate.

[0008] In order to achieve the above objectives, the first objective of the present invention is to disclose a demulsifier for treating oily wastewater, the molecular formula of which is as follows:

[0009]

[0010] Where:

[0011] m is a positive integer of 2-50, preferably a positive integer of 20-50.

[0012] n is a positive integer of 2-50, preferably a positive integer of 10-50.

[0013] p is a positive integer of 2-50, preferably a positive integer of 10-50.

[0014] Another object of the present invention is to provide a method for preparing the above-mentioned demulsifier for oily wastewater treatment, the preparation method comprising: under first high temperature and high pressure conditions, in the presence of a catalyst, sodium laurylaminopropionate and propylene oxide undergo an addition reaction to obtain an intercalated ether intermediate; secondly, adding a first ethylene oxide to undergo an addition reaction to obtain a mixed intercalated ether intermediate; and finally, in an acidic environment, under second high temperature and high pressure conditions, adding a second ethylene oxide to undergo an addition reaction, wherein the structural formula of the intercalated ether intermediate is shown in formula (1), and the structural formula of the mixed intercalated ether intermediate is shown in formula (2).

[0015] (1)

[0016] (2)

[0017] Wherein: m is a positive integer of 2-50, preferably a positive integer of 20-50; n is a positive integer of 2-50, preferably a positive integer of 10-50.

[0018] In the present invention, preferably, the molar ratio of propylene oxide, the first ethylene oxide and sodium laurylaminopropionate is 2-50:2-50:1; more preferably, the molar ratio of propylene oxide, the first ethylene oxide and sodium laurylaminopropionate is 10-50:5-50:1.

[0019] In the present invention, preferably, the molar ratio of the second ethylene oxide to sodium laurylaminopropionate is 2-50:1; more preferably, the molar ratio of the second ethylene oxide to sodium laurylaminopropionate is 5-50:1.

[0020] In the present invention, preferably, the catalyst is sodium hydroxide or potassium hydroxide, and the mass ratio of the catalyst to sodium dodecylaminopropionate is 0.005-0.05:1.

[0021] In the present invention, preferably, the first high temperature and high pressure conditions are a temperature of 120-160° C. and a pressure of 0.05-0.3 MPa.

[0022] In the present invention, preferably, the time of the propylene oxide addition reaction is 0.5-4 hours.

[0023] In the present invention, preferably, the time of the first ethylene oxide addition reaction is 0.5-4 hours.

[0024] In the present invention, preferably, the acidic environment is pH 3-4.

[0025] In the present invention, preferably, the second high temperature and high pressure conditions are a temperature of 130-170° C. and a pressure of 0.05-0.4 MPa.

[0026] In the present invention, preferably, the second ethylene oxide addition reaction time is 0.5-6 hours.

[0027] According to a more specific preferred embodiment, the preparation method of the demulsifier for oily wastewater treatment specifically comprises the following steps:

[0028] (1) Add sodium laurylaminopropionate, toluene, and catalyst to a high-pressure reactor, purge the reactor and pipeline with nitrogen for 2-3 minutes, stop purging, evacuate, introduce nitrogen, evacuate, repeat the above operation 3 times, introduce propylene oxide, increase the temperature, increase the pressure, keep the temperature for reaction, introduce the first ethylene oxide, adjust the reaction temperature and pressure, keep the temperature for reaction, cool to below 40°C, and stop the reaction;

[0029] (2) Open the reactor, adjust the pH to 3-4 with 1 mol / L hydrochloric acid, filter the reaction mixture, separate the liquids, and distill the toluene phase under reduced pressure to obtain a viscous liquid, which is then transferred to an autoclave;

[0030] (3) Purge the reactor and pipelines with nitrogen for 2-3 minutes, stop purging, evacuate, introduce nitrogen, evacuate, repeat the above operation 3 times, introduce the second ethylene oxide, increase the temperature, increase the pressure to keep the reaction warm, cool to below 40 ° C, adjust the pH to 7-8 with 1 mol / L sodium hydroxide, and obtain the product demulsifier.

[0031] Preferably, in step (1), the mass ratio of toluene to sodium dodecylaminopropionate is 3-5:1.

[0032] The reaction equation of the demulsifier of the present invention is:

[0033]

[0034]

[0035]

[0036] The demulsifier of the present invention is a weak cationic nonionic surfactant, the lipophilic groups are dodecyl and polyoxypropyl ether segments, and the hydrophilic groups are two polyoxyethylene ether segments and a tertiary amine. Most of the crude oil in the produced water of the oil field exists in the form of an O / W emulsion, and most of it is tiny oil droplets. The oil droplets have a negative charge on the surface and are very stable. The tertiary amine can neutralize the negatively charged oil droplets, causing the oil droplets to lose their repulsive effect and aggregate with each other, allowing the tiny oil droplets to aggregate and release to achieve the demulsification effect; the molecule of the present invention can enter the oil-water interface, replace the surfactant with strong emulsification, displace the surfactant molecules and other surface active substances, reduce the stability of the interfacial film, destroy the emulsification ability of the oil droplets, and make it easier for the small oil droplets to approach and condense, thereby achieving oil-water separation; the polyether segment in the molecule of the present invention can capture a large number of tiny oil droplets, has high flexibility, and is prone to internal rotation of the molecular chain, which increases the chance of oil droplet collision, forming oil droplets that are easy to aggregate and float to achieve the purpose of demulsification.

[0037] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0038] (1) The demulsifier of the present invention has the characteristics of cheap raw materials, wide sources and simple synthesis process;

[0039] (2) The demulsifier of the present invention has a good demulsification effect. When the concentration is 15 mg / L, the oil removal rate reaches more than 98%. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is the infrared spectrum characterization diagram of the demulsifier N7, a product of the present invention. DETAILED DESCRIPTION

[0041] The present invention will be further described in detail below with reference to specific examples and data. It should be understood that these examples are only for illustrating the present invention and are not intended to limit the scope of the present invention in any way.

[0042] Example 1 (1) Add 0.5 mol of sodium dodecylaminopropionate, 483 g of toluene, and 0.7 g of sodium hydroxide to a high-pressure reactor, purge the reactor and pipeline with nitrogen for 2 minutes, stop purging, evacuate, introduce nitrogen, evacuate, repeat the above operation 3 times, introduce 1 mol of propylene oxide, raise the temperature to 120°C, the pressure to 0.05 MPa, and keep the temperature for reaction for 1 hour, introduce 1 mol of ethylene oxide, adjust the reaction temperature to 125°C and the pressure to 0.05 MPa, keep the temperature for reaction for 0.5 hour, cool to below 40°C, and stop the reaction.

[0043] (2) Open the reactor and adjust the pH to 3-4 with 1 mol / L hydrochloric acid. Filter the reaction mixture, separate the liquids, and distill the toluene phase under reduced pressure to obtain a viscous liquid, which is then transferred to an autoclave.

[0044] (3) Purge the reactor and pipelines with nitrogen for 2 minutes, stop purging, evacuate, introduce nitrogen, evacuate, repeat the above operation 3 times, introduce 1 mol of ethylene oxide, raise the temperature to 130°C, reduce the pressure to 0.05 MPa, keep the temperature for 0.5 h, cool to below 40°C, adjust the pH to 7-8 with 1 mol / L sodium hydroxide, and obtain the product demulsifier N1.

[0045] Example 2 (1) 0.5 mol of sodium laurylaminopropionate, 419 g of toluene, and 1.2 g of sodium hydroxide were added to a high-pressure reactor. The reactor and pipeline were purged with nitrogen for 3 min, the purging was stopped, vacuum was applied, nitrogen was introduced, and vacuum was applied. The above operation was repeated 3 times. 2 mol of propylene oxide was introduced, the temperature was raised to 120°C, the pressure was reduced to 0.05 MPa, and the reaction was carried out at this temperature for 1 h. 5 mol of ethylene oxide was introduced, the reaction temperature was adjusted to 130°C and the pressure was adjusted to 0.05 MPa, the reaction was carried out at this temperature for 0.5 h, the temperature was lowered to below 40°C, and the reaction was stopped.

[0046] (2) Open the reactor and adjust the pH to 3-4 with 1 mol / L hydrochloric acid. Filter the reaction mixture, separate the liquids, and distill the toluene phase under reduced pressure to obtain a viscous liquid, which is then transferred to an autoclave.

[0047] (3) Purge the reactor and pipelines with nitrogen for 2 minutes, stop purging, evacuate, introduce nitrogen, evacuate, repeat the above operation 3 times, introduce 5 mol of ethylene oxide, raise the temperature to 135°C, reduce the pressure to 0.07 MPa, keep the temperature for 1 hour, cool to below 40°C, adjust the pH to 7-8 with 1 mol / L sodium hydroxide, and obtain the product demulsifier N2.

[0048] Example 3 (1) 0.5 mol of sodium laurylaminopropionate, 492 g of toluene, and 2.8 g of sodium hydroxide were added to a high-pressure reactor. The reactor and pipeline were purged with nitrogen for 2 min, the purging was stopped, vacuum was applied, nitrogen was introduced, and vacuum was applied. The above operation was repeated 3 times. 5 mol of propylene oxide was introduced, the temperature was raised to 125°C, the pressure was reduced to 0.1 MPa, and the reaction was kept warm for 0.5 h. 10 mol of ethylene oxide was introduced, the reaction temperature was adjusted to 140°C and the pressure was adjusted to 0.1 MPa, the reaction was kept warm for 1 h, the temperature was lowered to below 40°C, and the reaction was stopped.

[0049] (2) Open the reactor and adjust the pH to 3-4 with 1 mol / L hydrochloric acid. Filter the reaction mixture, separate the liquids, and distill the toluene phase under reduced pressure to obtain a viscous liquid, which is then transferred to an autoclave.

[0050] (3) Purge the reactor and pipelines with nitrogen for 2 minutes, stop purging, evacuate, introduce nitrogen, evacuate, repeat the above operation 3 times, introduce 8 mol of ethylene oxide, raise the temperature to 140°C, reduce the pressure to 0.1 MPa, keep the temperature and react for 2 hours, cool to below 40°C, adjust the pH to 7-8 with 1 mol / L sodium hydroxide, and obtain the product demulsifier N3.

[0051] Example 4 (1) 0.5 mol of sodium laurylaminopropionate, 505 g of toluene, and 3.8 g of sodium hydroxide were added to a high-pressure reactor. The reactor and pipeline were purged with nitrogen for 3 min, the purging was stopped, vacuum was applied, nitrogen was introduced, and vacuum was applied. The above operation was repeated 3 times. 10 mol of propylene oxide was introduced, the temperature was raised to 125°C, the pressure was reduced to 0.15 MPa, and the reaction was carried out at this temperature for 1 h. 15 mol of ethylene oxide was introduced, the reaction temperature was adjusted to 147°C and the pressure was adjusted to 0.1 MPa, the reaction was carried out at this temperature for 1 h, the temperature was lowered to below 40°C, and the reaction was stopped.

[0052] (2) Open the reactor and adjust the pH to 3-4 with 1 mol / L hydrochloric acid. Filter the reaction mixture, separate the liquids, and distill the toluene phase under reduced pressure to obtain a viscous liquid, which is then transferred to an autoclave.

[0053] (3) Purge the reactor and pipelines with nitrogen for 2 minutes, stop purging, evacuate, introduce nitrogen, evacuate, repeat the above operation 3 times, introduce 20 mol of ethylene oxide, raise the temperature to 148 ° C, reduce the pressure to 0.2 MPa, keep the temperature for 3 hours, cool to below 40 ° C, adjust the pH to 7-8 with 1 mol / L sodium hydroxide, and obtain the product demulsifier N4.

[0054] Example 5 (1) 0.5 mol of sodium laurylaminopropionate, 620 g of toluene, and 4.5 g of sodium hydroxide were added to a high-pressure reactor. The reactor and pipelines were purged with nitrogen for 2 min, the purging was stopped, vacuum was applied, nitrogen was introduced, and vacuum was applied. The above operation was repeated 3 times. 15 mol of propylene oxide was introduced, the temperature was raised to 135°C, the pressure was reduced to 0.15 MPa, and the reaction was carried out at this temperature for 2 h. 20 mol of ethylene oxide was introduced, the reaction temperature was adjusted to 150°C and the pressure was adjusted to 0.2 MPa, the reaction was carried out at this temperature for 2 h, the temperature was lowered to below 40°C, and the reaction was stopped.

[0055] (2) Open the reactor and adjust the pH to 3-4 with 1 mol / L hydrochloric acid. Filter the reaction mixture, separate the liquids, and distill the toluene phase under reduced pressure to obtain a viscous liquid, which is then transferred to an autoclave.

[0056] (3) Purge the reactor and pipelines with nitrogen for 2 minutes, stop purging, evacuate, introduce nitrogen, evacuate, repeat the above operation 3 times, introduce 25 mol of ethylene oxide, raise the temperature to 155°C, and the pressure to 0.28 MPa. Keep the temperature for 3 hours, cool to below 40°C, and adjust the pH to 7-8 with 1 mol / L sodium hydroxide to obtain the product demulsifier N5.

[0057] Example 6 (1) 0.5 mol of sodium laurylaminopropionate, 645 g of toluene, and 5.8 g of sodium hydroxide were added to a high-pressure reactor. The reactor and pipeline were purged with nitrogen for 3 minutes, the purging was stopped, vacuum was applied, nitrogen was introduced, and vacuum was applied. The above operation was repeated 3 times. 20 mol of propylene oxide was introduced, the temperature was raised to 140°C, the pressure was reduced to 0.2 MPa, and the reaction was carried out at this temperature for 3 hours. 25 mol of ethylene oxide was introduced, the reaction temperature was adjusted to 152°C and the pressure was adjusted to 0.22 MPa, the reaction was carried out at this temperature for 3 hours, the temperature was lowered to below 40°C, and the reaction was stopped.

[0058] (2) Open the reactor and adjust the pH to 3-4 with 1 mol / L hydrochloric acid. Filter the reaction mixture, separate the liquids, and distill the toluene phase under reduced pressure to obtain a viscous liquid, which is then transferred to an autoclave.

[0059] (3) Purge the reactor and pipelines with nitrogen for 3 minutes, stop purging, evacuate, introduce nitrogen, evacuate, repeat the above operation 3 times, introduce 25 mol of ethylene oxide, raise the temperature to 170°C, reduce the pressure to 0.4 MPa, keep the temperature for 6 hours, cool to below 40°C, adjust the pH to 7-8 with 1 mol / L sodium hydroxide, and obtain the product demulsifier N6.

[0060] Example 7 (1) 0.5 mol of sodium laurylaminopropionate, 633 g of toluene, and 7 g of potassium hydroxide were added to a high-pressure reactor. The reactor and pipelines were purged with nitrogen for 2 min, the purging was stopped, vacuum was applied, nitrogen was introduced, and vacuum was applied. The above operation was repeated 3 times. 25 mol of propylene oxide was introduced, the temperature was raised to 150°C, the pressure was reduced to 0.28 MPa, and the reaction was carried out at this temperature for 4 h. 25 mol of ethylene oxide was introduced, the reaction temperature was adjusted to 160°C and the pressure was adjusted to 0.3 MPa, the reaction was carried out at this temperature for 4 h, the temperature was lowered to below 40°C, and the reaction was stopped.

[0061] (2) Open the reactor and adjust the pH to 3-4 with 1 mol / L hydrochloric acid. Filter the reaction mixture, separate the liquids, and distill the toluene phase under reduced pressure to obtain a viscous liquid, which is then transferred to an autoclave.

[0062] (3) Purge the reactor and pipelines with nitrogen for 2 minutes, stop purging, evacuate, introduce nitrogen, evacuate, repeat the above operation 3 times, introduce 25 mol of ethylene oxide, raise the temperature to 165°C, and the pressure to 0.38 MPa. Keep the temperature for 6 hours, cool to below 40°C, and adjust the pH to 7-8 with 1 mol / L sodium hydroxide to obtain the product demulsifier N7.

[0063] Example 8 (1) 0.5 mol of sodium laurylaminopropionate, 697 g of toluene, and 6.5 g of potassium hydroxide were added to a high-pressure reactor. The reactor and pipelines were purged with nitrogen for 2 min, the purging was stopped, vacuum was applied, nitrogen was introduced, and vacuum was applied. The above operation was repeated 3 times. 25 mol of propylene oxide was introduced, the temperature was raised to 150°C, the pressure was reduced to 0.3 MPa, and the reaction was carried out at this temperature for 4 h. 20 mol of ethylene oxide was introduced, the reaction temperature was adjusted to 158°C and the pressure was adjusted to 0.3 MPa, the reaction was carried out at this temperature for 4 h, the temperature was lowered to below 40°C, and the reaction was stopped.

[0064] (2) Open the reactor and adjust the pH to 3-4 with 1 mol / L hydrochloric acid. Filter the reaction mixture, separate the liquids, and distill the toluene phase under reduced pressure to obtain a viscous liquid, which is then transferred to an autoclave.

[0065] (3) Purge the reactor and pipelines with nitrogen for 3 minutes, stop purging, evacuate, introduce nitrogen, evacuate, repeat the above operation 3 times, introduce 20 mol of ethylene oxide, raise the temperature to 165°C, and the pressure to 0.35 MPa. Keep the reaction at this temperature for 5 hours, cool it to below 40°C, and adjust the pH to 7-8 with 1 mol / L sodium hydroxide to obtain the product demulsifier N8.

[0066] Example 9 (1) 0.5 mol of sodium laurylaminopropionate, 685 g of toluene, and 6.2 g of potassium hydroxide were added to a high-pressure reactor. The reactor and pipelines were purged with nitrogen for 2 min, the purging was stopped, vacuum was applied, nitrogen was introduced, and vacuum was applied. The above operation was repeated 3 times. 25 mol of propylene oxide was introduced, the temperature was raised to 150°C, the pressure was reduced to 0.3 MPa, and the reaction was carried out at this temperature for 4 h. 15 mol of ethylene oxide was introduced, the reaction temperature was adjusted to 156°C and the pressure was adjusted to 0.28 MPa, the reaction was carried out at this temperature for 4 h, the temperature was lowered to below 40°C, and the reaction was stopped.

[0067] (2) Open the reactor and adjust the pH to 3-4 with 1 mol / L hydrochloric acid. Filter the reaction mixture, separate the liquids, and distill the toluene phase under reduced pressure to obtain a viscous liquid, which is then transferred to an autoclave.

[0068] (3) Purge the reactor and pipelines with nitrogen for 3 minutes, stop purging, evacuate, introduce nitrogen, evacuate, repeat the above operation 3 times, introduce 20 mol of ethylene oxide, raise the temperature to 162°C, and the pressure to 0.32 MPa, keep the temperature and react for 5 hours, cool to below 40°C, and adjust the pH to 7-8 with 1 mol / L sodium hydroxide to obtain the product demulsifier N9.

[0069] Example 10 Indoor Evaluation of Demulsifier

[0070] The produced water of ASP flooding in a certain oil field has an oil content of 1450 mg / L. The demulsification experiment of the present invention was carried out on it. The experimental method refers to the "SY / T5797-1993 Method for Evaluating the Performance of Demulsifiers for Oil-in-Water Emulsions". The demulsifier AES (sodium nonylphenol polyoxyethylene sulfate) was used for comparative experiment. The experimental results are shown in Table 1.

[0071] Table 1 Demulsifier demulsification test results (oil removal rate, %)

[0072] Demulsifier 5mg / L,% 10mg / L,% 15mg / L,% <![CDATA[N1]]> 85.2 90.3 98.1 <![CDATA[N2]]> 86.3 92.9 98.2 <![CDATA[N3]]> 89.5 93.3 98.4 <![CDATA[N4]]> 92.6 95.4 98.6 <![CDATA[N5]]> 91.6 94.3 98.5 <![CDATA[N6]]> 93.8 96.5 98.8 <![CDATA[N7]]> 94.7 98 99.2 <![CDATA[N8]]> 94.1 97.6 99 <![CDATA[N9]]> 93.8 97.2 99 AES 78.8 86.6 92.3

[0073] From Table 1 we can see that:

[0074] (1) The oil removal rate of the demulsifiers N1-N9 of the present invention reached 85% or above when used at a concentration of 5 mg / L, with the highest reaching 94.7%; while the oil removal rate of AES was 78.8% when used at a concentration of 5 mg / L;

[0075] (2) The oil removal rate of the demulsifiers N1-N9 of the present invention reached 90% or above when the concentration was 10 mg / L, with the highest reaching 97.6%; while the oil removal rate of AES was 86.6% when the concentration was 10 mg / L;

[0076] (3) The oil removal rate of the demulsifiers N1-N9 of the present invention reached 98% or above when the concentration was 15 mg / L, with the highest reaching 99.2%; while the oil removal rate of AES was 92.3% when the concentration was 15 mg / L.

[0077] Compared with the prior art products, the demulsifier of the present invention has a good oil removal effect.

[0078] Example 11 Demulsifier Field Application

[0079] The water from the joint station L4 is produced water from the oilfield binary flooding. A field test was carried out at the joint station L4 with a treatment scale of 120m 3 / d, the oil content of the incoming water was 1320 mg / L, the salinity of the produced water was 18900 mg / L, and the temperature was 68°C. The demulsifier N7 of the present invention was used to demulsify the produced water of the joint station L4. The dosage of demulsifier N7 was 1.8 kg / d, and the concentration was 15 mg / L. After treatment, the oil content of the produced water was reduced to 23.76 mg / L, and the oil removal rate reached 98.2%, meeting the process requirements.

[0080] Example 12 Infrared spectroscopy characterization

[0081] Product N7 was characterized by infrared spectroscopy, and the results are as follows: Figure 1 shown.

[0082] Figure 1 Medium, 2942cm -1 It is the absorption peak of the CH bond in dodecyl; 1343cm -1 is the CN bond absorption peak; 1360cm -1 It is the absorption peak of polyoxypropylene ether; 1112cm -1 It is the absorption peak of polyoxyethylene ether segment.

[0083] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for preparing an emulsifier for treating oily wastewater, characterized in that: The preparation method comprises: under first high temperature and high pressure conditions, in the presence of a catalyst, sodium laurylaminopropionate and propylene oxide undergo an addition reaction to obtain an intercalated ether intermediate; secondly, adding a first ethylene oxide to undergo an addition reaction to obtain a mixed intercalated ether intermediate; and finally, in an acidic environment, under second high temperature and high pressure conditions, adding a second ethylene oxide to undergo an addition reaction to obtain a demulsifier, wherein the structural formula of the intercalated ether intermediate is shown in formula (1), and the structural formula of the mixed intercalated ether intermediate is shown in formula (2). （1） （2） Wherein: m is a positive integer between 2 and 50, and n is a positive integer between 2 and 50; The molar ratio of propylene oxide, the first ethylene oxide and sodium laurylaminopropionate is 2-50:2-50:1; The demulsifier molecular formula is as follows: ， Where: m is a positive integer from 2 to 50; n is a positive integer from 2 to 50; p is a positive integer from 2 to 50.

2. The method for preparing a demulsifier for oily wastewater treatment according to claim 1, wherein: The molar ratio of the propylene oxide, the first ethylene oxide and the sodium laurylaminopropionate is 10-50:5-50:

1.

3. The method for preparing a demulsifier for oily wastewater treatment according to claim 1, wherein: The molar ratio of the second ethylene oxide to sodium laurylaminopropionate is 2-50:

1.

4. The method for preparing a demulsifier for oily wastewater treatment according to claim 1, wherein: The catalyst is sodium hydroxide or potassium hydroxide, and the mass ratio of the catalyst to sodium dodecylaminopropionate is 0.005-0.05:

1.

5. The method for preparing a demulsifier for oily wastewater treatment according to claim 1, wherein: The first high temperature and high pressure conditions are a temperature of 120-160° C. and a pressure of 0.05-0.3 MPa.

6. The method for preparing a demulsifier for oily wastewater treatment according to claim 1, characterized in that: The time of the propylene oxide addition reaction is 0.5-4h.

7. The method for preparing a demulsifier for oily wastewater treatment according to claim 1, characterized in that: The time of the first ethylene oxide addition reaction is 0.5-4 hours.

8. The method for preparing a demulsifier for oily wastewater treatment according to claim 1, characterized in that: The second high temperature and high pressure conditions are a temperature of 130-170° C. and a pressure of 0.05-0.4 MPa.

9. The method for preparing a demulsifier for oily wastewater treatment according to claim 1, characterized in that: The time of the second ethylene oxide addition reaction is 0.5-6h.

10. A demulsifier for treating oily wastewater, characterized in that: The demulsifier molecular formula is as follows: ， Where: m is a positive integer from 2 to 50; n is a positive integer from 2 to 50; p is a positive integer from 2 to 50.

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