Recyclable degradable cleaning macromolecular surfactant for oily sludge and application thereof

Abstract

The application discloses a recyclable and degradable macromolecular surfactant for cleaning oily sludge and application thereof. The macromolecular surfactant is prepared from acrylamide, long-chain alkyl methacrylate and tertiary amino-substituted methacrylate as raw materials through free radical polymerization. The macromolecular surfactant is dissolved in water to prepare a cleaning solution, and the cleaning solution can efficiently wash and remove oily sludge. CO2 and N2 are introduced into oily emulsion after the oily sludge is cleaned, or dilute hydrochloric acid and dilute alkali aqueous solution are sequentially added, the hydrophilicity and hydrophobicity of the macromolecular surfactant are changed through pH control, the macromolecular surfactant and the oil phase are separated, oil resources are recovered, and the cleaning solution containing the macromolecular surfactant can be recycled. The residual macromolecular surfactant in the deoiled sludge after cleaning can be degraded under the action of environmental microorganisms.

Description

Technical Field

[0001] This invention relates to the field of harmless treatment technology for oily sludge, specifically to a recyclable and easily degradable macromolecular surfactant for cleaning oily sludge and its application. Background Technology

[0002] High-concentration oily sludge (oil content ≥ 10 wt%) is mainly treated using chemical cleaning methods. The key to cleaning is the surfactant used to separate the oily sludge. Highly effective surfactants for cleaning oily sludge not only achieve the harmless treatment of the sludge but also allow for the recovery of valuable petroleum resources.

[0003] Currently, the surfactants used for cleaning oily sludge are mainly small-molecule surfactants such as dodecylbenzenesulfonic acid, dodecyl sulfuric acid, and sodium petroleum sulfonate. These small-molecule surfactants utilize their amphiphilic molecular structure to disrupt the stable adsorption system of the "oil-soil-water" three-phase system in oily sludge. By modifying the soil interface, they achieve the separation of petroleum hydrocarbons from solid particles, ultimately achieving the goal of harmless treatment of oily sludge and oil resource recovery. Research results show that small-molecule surfactants are effective in cleaning light components (saturated hydrocarbons and aromatic hydrocarbons) in oily sludge, but are less effective in removing heavy components such as gums and asphaltenes from petroleum, resulting in a low total petroleum hydrocarbon (TPH) removal rate after cleaning with small-molecule surfactants. Compared with small-molecule surfactants, macromolecular surfactants (MS) have unique advantages in removing heavy petroleum hydrocarbons and improving TPH removal rates.

[0004] Current research has used esterification products of fatty alcohol polyoxyethylene ether and acrylic acid as main monomers, sodium styrene sulfonate as a hydrophilic monomer, and dodecyl acrylate as a hydrophobic monomer to form macromolecular surfactants via free radical polymerization for deep cleaning of high-concentration oily sludge. However, the limiting factors for using such macromolecular surfactants to clean oily sludge are high production costs and the inability to recycle them. By optimizing the molecular structure of macromolecular surfactants and combining it with systematic control of cleaning process parameters, it is hoped that the cleaning performance can be improved while achieving the recycling of cleaning solutions containing macromolecular surfactants. While retaining the cleaning performance of macromolecular surfactants in cleaning oily sludge, optimizing their molecular topology and introducing functional groups that are easily degraded by environmental microorganisms could ensure their rapid degradation into non-toxic small molecules in the natural environment; however, to date, there are few related studies and applications reported. Summary of the Invention

[0005] The purpose of this invention is to provide a recyclable and biodegradable macromolecular surfactant for cleaning oily sludge and its application. The macromolecular surfactant, while ensuring efficient removal of heavy petroleum hydrocarbons from oily sludge, also has pH-responsive characteristics, enabling recycling and easy degradation.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A recyclable and biodegradable macromolecular surfactant for cleaning oily sludge, with the following structural formula:

[0008]

[0009] In the above structural formula, x = 200~250, y = 15~30, z = 50~60, m = 12~18, n = 1~2, and the total molecular weight is 10. 3 ~10 6 g / mol.

[0010] Furthermore, the preparation process of the macromolecular surfactant is as follows: acrylamide, long-chain alkyl methacrylate and tertiary amino-substituted methacrylate are dissolved in deionized water at a mass ratio of (1~5):1:(1~5), and the pH is adjusted to 5.5~8.5; then an initiator solution is added, and N2 is introduced for 20~30 min.

[0011] The ratio of the amount of initiator to the total mass of all monomers is (1~20):1000; the total mass of all monomers is the total mass of acrylamide, long-chain alkyl methacrylate, and tertiary amino-substituted methacrylate.

[0012] Finally, the system is heated to 40-85 °C and the reaction time is 4-8 h. After the reaction is complete, the product is collected and dried at 30-80 °C for 20-48 h to obtain a recyclable and biodegradable macromolecular surfactant for cleaning oily sludge.

[0013] Further, the initiator is at least one of ammonium persulfate, potassium persulfate, or sodium persulfate; the long-chain alkyl methacrylate is at least one of tetradecyl methacrylate, hexadecyl methacrylate, or octadecyl methacrylate; and the tertiary amino-substituted methacrylate is at least one of dimethylaminoethyl methacrylate or diethylaminoethyl methacrylate.

[0014] Application of the macromolecular surfactant in cleaning oily sludge: The macromolecular surfactant is dissolved in water to prepare a cleaning solution of 0.1~0.5 wt%. After the cleaning solution is injected into the oily sludge, it is stirred thoroughly and cleaned at 40~90℃ for 60~120 min. The mass ratio of the cleaning solution to the oily sludge is (5~20):1. After cleaning, solid-liquid separation is performed to obtain an oily emulsion and deoiled sludge. The petroleum hydrocarbon content in the deoiled sludge is determined, and the oil removal efficiency (RE) is calculated. The oil removal efficiency of the macromolecular surfactant on the oily sludge is greater than 70%.

[0015] The oil-containing emulsion is demulsified and separated by the following process: CO2 is introduced into the oil-containing emulsion or a dilute hydrochloric acid aqueous solution is added to lower the pH of the system to 4-6.9, and the emulsion is demulsified into an oil layer and an aqueous layer containing the macromolecular surfactant.

[0016] After demulsification and separation, the aqueous layer is regenerated and reused as a cleaning solution. The specific process is as follows: after separating the oil phase, N2 is introduced into the aqueous layer containing the macromolecular surfactant or a dilute alkaline solution is added to raise the pH of the system to 7-9; then the macromolecular surfactant is added to the system at a rate of 1-5 wt% of the initial dosage; then water is added to restore the volume of the cleaning solution to the initial dosage, resulting in a cleaning solution that can be recycled for the treatment of oily sludge.

[0017] After the oily sludge is washed, the macromolecular surfactants remaining in the solid phase of the deoiled sludge can be degraded in the environment, with a degradation efficiency (DE) of more than 70% at 28 days.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] The macromolecular surfactant described in this invention possesses the properties of high efficiency in cleaning oily sludge, recyclability, and easy biodegradability. The performance advantages of the macromolecular surfactant in cleaning oily sludge are shown in Table 1:

[0020] Table 1. Cleaning effect and degradation rate

[0021] Detailed Implementation

[0022] The present invention will be further illustrated below with specific embodiments, which will help to understand the present invention, but does not limit the scope of the present invention.

[0023] In this invention, the oil content of the oily sludge is ≥ 10wt%, and preferably it is capable of treating oily sludge with an oil content of 10wt% to 60wt%.

[0024] Example 1

[0025] Preparation of a recyclable and biodegradable macromolecular surfactant for cleaning oily sludge: Acrylamide, hexadecyl methacrylate, and dimethylaminoethyl methacrylate were dissolved in deionized water at a mass ratio of 5:1:2. After complete dissolution, the pH was adjusted to 7.5. 0.1 wt% ammonium persulfate aqueous solution was added, with the ratio of ammonium persulfate to the total mass of all monomers being 3:1000. N2 was then introduced to remove oxygen for 30 min.

[0026] Finally, the system was heated to 65°C and stirred for 6 hours. After the reaction was completed, the product was collected and dried at 40°C for 48 hours to obtain a recyclable and biodegradable macromolecular surfactant for cleaning oily sludge (referred to as macromolecular surfactant).

[0027] Application of recyclable and biodegradable macromolecular surfactants in the cleaning of oily sludge: The macromolecular surfactants were dissolved in water to prepare a 0.3 wt% cleaning solution, which was then mixed with oily sludge (oil content 15 wt%) at a mass ratio of 15:1 (cleaning solution: oily sludge). The mixture was then cleaned at 65 ℃ for 120 min. After cleaning, solid-liquid separation was performed to obtain an oily emulsion and de-oiled sludge. The petroleum hydrocarbon content in the de-oiled sludge was measured, and the oil removal rate was calculated to be 72.4%. The biodegradation rate of the residual macromolecular surfactants in the de-oiled sludge after cleaning reached 73.8% in the environment after 28 days.

[0028] The oil-containing emulsion is demulsified by introducing CO2 into it to lower the pH of the system to 6.5. The emulsion demulsifies into an oil layer and an aqueous layer containing macromolecular surfactants.

[0029] After demulsification and separation, the aqueous layer was regenerated and reused as a cleaning solution: After separating the oil phase, N2 was introduced into the aqueous layer for 30 minutes to raise the pH of the system to 8. Then, a large-molecule surfactant was added to the resulting liquid at 3 wt% of the initial dosage; water was added to restore the volume of the cleaning solution to the initial dosage, resulting in a cleaning solution that can be recycled for treating oily sludge. The oil removal rates of the 5th and 10th cleanings of the oily sludge were 71.5% and 70.1%, respectively.

[0030] Example 2

[0031] Preparation of a recyclable and biodegradable macromolecular surfactant for cleaning oily sludge: Acrylamide, hexadecyl methacrylate, and diethylaminoethyl methacrylate were weighed at a mass ratio of 5:1:3 and dissolved in deionized water. After complete dissolution by stirring, the pH was adjusted to 7.5. 0.1 wt% ammonium persulfate aqueous solution was added, with the ratio of ammonium persulfate to the total mass of all monomers being 6:1000. N2 was bubbled through the solution for 30 min to remove oxygen. The system was then heated to 65℃ and stirred for 6 h. After the reaction was complete, the product was collected and dried at 60℃ for 48 h to obtain the recyclable and biodegradable macromolecular surfactant for cleaning oily sludge.

[0032] Application of recyclable and biodegradable macromolecular surfactants in the cleaning of oily sludge: The macromolecular surfactants were dissolved in water to prepare a 0.3 wt% cleaning solution, which was then mixed with oily sludge (oil content 15 wt%) at a mass ratio of 20:1. The mixture was then cleaned at 65 ℃ for 120 min. After cleaning, solid-liquid separation was performed to obtain an oily emulsion and deoiled sludge. The petroleum hydrocarbon content in the deoiled sludge was measured, and the oil removal rate was calculated to be 74.2%. After cleaning, the biodegradation rate of the residual macromolecular surfactants in the deoiled sludge reached 71.7% in the environment after 28 days.

[0033] The oil-containing emulsion is demulsified by adding a dilute hydrochloric acid aqueous solution to lower the pH of the emulsion to 6.5. The emulsion is demulsified into an oil layer and an aqueous layer containing macromolecular surfactants.

[0034] After demulsification and separation, the aqueous layer was regenerated and reused as a cleaning solution: After separating the oil phase, a dilute alkaline aqueous solution was added to the aqueous layer to raise the pH of the system to 8. Then, a large-molecule surfactant was added to the resulting liquid at a dosage of 3 wt% of the initial dosage. Water was added to restore the volume of the cleaning solution to the initial dosage, resulting in a cleaning solution that can be recycled for the treatment of oily sludge. The oil removal rates of the 5th and 10th cleanings of the oily sludge were 72.3% and 70.5%, respectively.

[0035] Example 3

[0036] Preparation of a recyclable and biodegradable macromolecular surfactant for cleaning oily sludge: Acrylamide, tetradecyl methacrylate, and dimethylaminoethyl methacrylate were weighed at a mass ratio of 4:1:2 and dissolved in deionized water. After complete dissolution by stirring, the pH was adjusted to 7.5. 0.1 wt% ammonium persulfate aqueous solution was added, with the ratio of ammonium persulfate to the total mass of all monomers being 3:1000. N2 was bubbled through the solution for 30 min to remove oxygen. The system was then heated to 65℃ and stirred for 6 h. After the reaction was complete, the product was collected and dried at 60℃ for 48 h to obtain the recyclable and biodegradable macromolecular surfactant for cleaning oily sludge.

[0037] Application of recyclable and biodegradable macromolecular surfactants in the cleaning of oily sludge: The macromolecular surfactants were dissolved in water to prepare a 0.3 wt% cleaning solution, which was then mixed with oily sludge (oil content 16 wt%) at a mass ratio of 15:1 and cleaned at 65 ℃ for 120 min. After cleaning, solid-liquid separation was performed to obtain an oily emulsion and deoiled sludge, respectively. The petroleum hydrocarbon content in the deoiled sludge was measured, and the oil removal rate was calculated to be 71.3%. After cleaning, the biodegradation rate of the residual macromolecular surfactants in the deoiled sludge reached 74.1% in the environment after 28 days.

[0038] The oil-containing emulsion is demulsified by introducing CO2 into it to lower the pH to 6.5. The emulsion demulsifies into an oil layer and an aqueous layer containing macromolecular surfactants.

[0039] After demulsification and separation, the aqueous layer is regenerated and reused as a cleaning solution: After separating the oil phase, N2 is introduced into the aqueous layer to raise the pH of the system to 8. Then, a large-molecule surfactant is added to the resulting liquid at a dosage of 3 wt% of the initial dosage. Water is added to restore the volume of the cleaning solution to the initial dosage, resulting in a cleaning solution that can be recycled for the treatment of oily sludge. The oil removal rates of the 5th and 10th cleanings of the oily sludge were 69.7% and 66.4%, respectively.

[0040] Example 4

[0041] Preparation of a recyclable and biodegradable macromolecular surfactant for cleaning oily sludge: Acrylamide, tetradecyl methacrylate, and diethylaminoethyl methacrylate were weighed at a mass ratio of 4:1:2 and dissolved in deionized water. After complete dissolution by stirring, the pH was adjusted to 7.5. 0.1 wt% ammonium persulfate aqueous solution was added, with the ratio of ammonium persulfate to the total mass of all monomers being 8:1000. N2 was bubbled through the solution for 30 min to remove oxygen. The system was then heated to 65℃ and stirred for 6 h. After the reaction was complete, the product was collected and dried at 60℃ for 48 h to obtain the recyclable and biodegradable macromolecular surfactant for cleaning oily sludge.

[0042] Application of recyclable and biodegradable macromolecular surfactants in the cleaning of oily sludge: The macromolecular surfactants were dissolved in water to prepare a 0.3 wt% cleaning solution, which was then mixed with oily sludge (oil content 15 wt%) at a mass ratio of 15:1. The solution was then used for cleaning at 65 °C for 120 min. After cleaning, solid-liquid separation was performed to obtain an oily emulsion and de-oiled sludge. The petroleum hydrocarbon content in the de-oiled sludge was measured, and the oil removal rate was calculated to be 72.5%. The biodegradation rate of the residual macromolecular surfactants in the de-oiled sludge after cleaning reached 73.5% in the environment after 28 days.

[0043] The oil-containing emulsion is demulsified by adding a dilute hydrochloric acid aqueous solution to lower the pH of the emulsion to 6.5. The emulsion is demulsified into an oil layer and an aqueous layer containing macromolecular surfactants.

[0044] After demulsification and separation, the aqueous layer is regenerated and reused as a cleaning solution: After separating the oil phase, a dilute alkaline aqueous solution is added to the aqueous layer containing macromolecular surfactants to raise the pH of the system to 8.5. Then, macromolecular surfactants are added to the resulting liquid at a dosage of 5 wt% of the initial dosage. Water is added to restore the volume of the cleaning solution to the initial dosage, resulting in a cleaning solution that can be recycled for the treatment of oily sludge. The oil removal rates of the 5th and 10th cleanings of the oily sludge were 70.1% and 69.2%, respectively.

[0045] Example 5

[0046] Preparation of a recyclable and biodegradable macromolecular surfactant for cleaning oily sludge: Acrylamide, octadecyl methacrylate, and dimethylaminoethyl methacrylate were weighed at a mass ratio of 5:1:1 and dissolved in deionized water. After complete dissolution by stirring, the pH was adjusted to 7.5. 0.1 wt% ammonium persulfate aqueous solution was added, with the ratio of ammonium persulfate to the total mass of all monomers being 5:1000. N2 was bubbled through the solution for 30 min to remove oxygen. The system was then heated to 65℃ and stirred for 6 h. After the reaction was complete, the product was collected and dried at 60℃ for 48 h to obtain the recyclable and biodegradable macromolecular surfactant for cleaning oily sludge.

[0047] Application of recyclable and biodegradable macromolecular surfactants in the cleaning of oily sludge: The macromolecular surfactants were dissolved in water to prepare a 0.3 wt% cleaning solution, which was then mixed with oily sludge (oil content 15 wt%) at a mass ratio of 9:1. The solution was cleaned at 75 ℃ for 120 min. After cleaning, solid-liquid separation was performed to obtain an oily emulsion and deoiled sludge. The petroleum hydrocarbon content in the deoiled sludge was measured, and the oil removal rate was calculated to be 75.3%. After cleaning, the biodegradation rate of the residual macromolecular surfactants in the deoiled sludge reached 70.2% in the environment after 28 days.

[0048] The oil-containing emulsion is demulsified by introducing CO2 into it to lower the pH to 6.5. The emulsion demulsifies into an oil layer and an aqueous layer containing macromolecular surfactants.

[0049] After demulsification and separation, the aqueous layer is regenerated and reused as a cleaning solution: After separating the oil phase, N2 is introduced into the aqueous layer containing macromolecular surfactants to raise the pH of the system to 8.5. Then, macromolecular surfactants are added to the resulting liquid at a dosage of 5 wt% of the initial dosage; water is added to restore the volume of the cleaning solution to the initial dosage, resulting in a cleaning solution that can be recycled for the treatment of oily sludge. The oil removal rates of the 5th and 10th cleanings of the oily sludge were 73.5% and 72.3%, respectively.

[0050] Example 6

[0051] Preparation of a recyclable and biodegradable macromolecular surfactant for cleaning oily sludge: Acrylamide, hexadecyl methacrylate, and diethylaminoethyl methacrylate were weighed at a mass ratio of 5:1:1 and dissolved in deionized water. After complete dissolution by stirring, the pH was adjusted to 7.5. 0.1 wt% ammonium persulfate aqueous solution was added, with the ratio of ammonium persulfate to the total mass of all monomers being 5:1000. N2 was bubbled through the solution for 30 min to remove oxygen. The system was then heated to 65℃ and stirred for 6 h. After the reaction was complete, the product was collected and dried at 60℃ for 48 h to obtain the recyclable and biodegradable macromolecular surfactant for cleaning oily sludge.

[0052] Application of recyclable and biodegradable macromolecular surfactants in the cleaning of oily sludge: The macromolecular surfactants were dissolved in water to prepare a 0.3 wt% cleaning solution, which was then mixed with oily sludge (oil content 15 wt%) at a mass ratio of 15:1. The mixture was then cleaned at 75 ℃ for 120 min. After cleaning, solid-liquid separation was performed to obtain an oily emulsion and deoiled sludge. The petroleum hydrocarbon content in the deoiled sludge was measured, and the oil removal rate was calculated to be 74.3%. After cleaning, the biodegradation rate of the residual macromolecular surfactants in the deoiled sludge reached 72.8% in the environment after 28 days.

[0053] The oil-containing emulsion is demulsified by adding a dilute hydrochloric acid aqueous solution to lower the pH of the emulsion to 6.5. The emulsion is demulsified into an oil layer and an aqueous layer containing macromolecular surfactants.

[0054] After demulsification and separation, the aqueous layer was regenerated and reused as a cleaning solution: After separating the oil phase, a dilute alkaline aqueous solution was added to the aqueous layer to raise the pH of the system to 8. Then, a large-molecule surfactant was added to the resulting liquid at a dosage of 5 wt% of the initial dosage. Water was added to restore the volume of the cleaning solution to the initial dosage, resulting in a cleaning solution that can be recycled for the treatment of oily sludge. The oil removal rates of the 5th and 10th cleanings of the oily sludge were 73.7% and 71.5%, respectively.

[0055] Example 7

[0056] Preparation of a recyclable and biodegradable macromolecular surfactant for cleaning oily sludge: Acrylamide, octadecyl methacrylate, and dimethylaminoethyl methacrylate were weighed at a mass ratio of 5:1:2 and dissolved in deionized water. After complete dissolution by stirring, the pH was adjusted to 7.5. 0.1 wt% of ammonium persulfate aqueous solution was added, with the ratio of ammonium persulfate to the total mass of all monomers being 5:1000. After purging with N2 for 30 min to remove oxygen, the system was heated to 65℃ and stirred for 6 h. After the reaction was complete, the product was collected and dried at 60℃ for 48 h to obtain the recyclable and biodegradable macromolecular surfactant for cleaning oily sludge.

[0057] Application of recyclable and biodegradable macromolecular surfactants in the cleaning of oily sludge: The macromolecular surfactants were dissolved in water to prepare a 0.3 wt% cleaning solution, which was then mixed with oily sludge (oil content 14 wt%) at a mass ratio of 18:1 and cleaned at 75 ℃ for 120 min. After cleaning, solid-liquid separation was performed to obtain an oily emulsion and deoiled sludge, respectively. The petroleum hydrocarbon content in the deoiled sludge was measured, and the oil removal rate was calculated to be 75.9%. After cleaning, the biodegradation rate of the residual macromolecular surfactants in the deoiled sludge reached 73.9% in the environment after 28 days.

[0058] The oil-containing emulsion is demulsified by adding a dilute hydrochloric acid aqueous solution to lower the pH of the emulsion to 6.5. The emulsion is demulsified into an oil layer and an aqueous layer containing macromolecular surfactants.

[0059] After demulsification and separation, the aqueous layer is regenerated and reused as a cleaning solution: After separating the oil phase, a dilute alkaline aqueous solution is added to the aqueous layer containing macromolecular surfactants to raise the pH of the system to 8.5. Then, macromolecular surfactants are added to the resulting liquid at a dosage of 3 wt% of the initial dosage. Water is added to restore the volume of the cleaning solution to the initial dosage, resulting in a cleaning solution that can be recycled for the treatment of oily sludge. The oil removal rates of the 5th and 10th cleanings of the oily sludge were 74.5% and 73.1%, respectively.

[0060] Example 8

[0061] Preparation of a recyclable and biodegradable macromolecular surfactant for cleaning oily sludge: Acrylamide, octadecyl methacrylate, and diethylaminoethyl methacrylate were weighed at a mass ratio of 5:1:2 and dissolved in deionized water. After complete dissolution by stirring, the pH was adjusted to 7.5. 0.1 wt% ammonium persulfate aqueous solution was added, with the ratio of ammonium persulfate to the total mass of all monomers being 5:1000. N2 was bubbled through the solution for 30 min to remove oxygen. The system was then heated to 65℃ and stirred for 6 h. After the reaction was complete, the product was collected and dried at 60℃ for 48 h to obtain the recyclable and biodegradable macromolecular surfactant for cleaning oily sludge.

[0062] Application of recyclable and biodegradable macromolecular surfactants in the cleaning of oily sludge: The macromolecular surfactants were dissolved in water to prepare a 0.3 wt% cleaning solution, which was then mixed with oily sludge (oil content 15 wt%) at a mass ratio of 20:1 and cleaned at 75 ℃ for 120 min. After cleaning, solid-liquid separation was performed to obtain an oily emulsion and deoiled sludge, respectively. The petroleum hydrocarbon content in the deoiled sludge was measured, and the oil removal rate was calculated to be 78.6%. After cleaning, the biodegradation rate of the residual macromolecular surfactants in the deoiled sludge reached 74.2% in the environment after 28 days.

[0063] The oil-containing emulsion is demulsified by introducing CO2 into it to lower the pH to 6.5. The emulsion demulsifies into an oil layer and an aqueous layer containing macromolecular surfactants.

[0064] After demulsification and separation, the aqueous layer is regenerated and reused as a cleaning solution: After separating the oil phase, N2 is introduced into the aqueous layer containing macromolecular surfactants to raise the pH of the system to 8.5. Then, macromolecular surfactants are added to the resulting liquid at a dosage of 3 wt% of the initial dosage; water is added to restore the volume of the cleaning solution to the initial dosage, resulting in a cleaning solution that can be recycled for the treatment of oily sludge. The oil removal rates of the 5th and 10th cleanings of the oily sludge were 76.4% and 73.7%, respectively.

[0065] Comparative Example 1

[0066] This comparative example, based on Example 8, does not introduce diethylaminoethyl methacrylate, and the mass ratio of acrylamide to hexadecyl methacrylate is 5:1 to prepare the surfactant.

[0067] The surfactant was used to clean oily sludge, following the same cleaning process as in Example 8. After cleaning, solid-liquid separation was performed to obtain an oily emulsion and deoiled sludge. The petroleum hydrocarbon content in the deoiled sludge was measured, and the oil removal rate was calculated to be 46.3%. After cleaning, the biodegradation rate of the residual macromolecular surfactant in the deoiled sludge reached 65.6% in the environment after 28 days.

[0068] Furthermore, this surfactant cannot achieve a reversible hydrophilic-hydrophobic structural transformation by introducing CO2 / N2 or adding dilute hydrochloric acid or dilute alkaline aqueous solution, and the prepared cleaning solution for cleaning oily sludge cannot achieve recycling efficiency close to that of the initial cleaning.

[0069] Comparative Example 2

[0070] This comparative example, based on Example 8, does not introduce diethylaminoethyl methacrylate, and the mass ratio of acrylamide to octadecyl methacrylate is 5:1 to prepare the surfactant.

[0071] The surfactant was used to clean oily sludge, following the same cleaning process as in Example 8. After cleaning, solid-liquid separation was performed to obtain an oily emulsion and deoiled sludge. The petroleum hydrocarbon content in the deoiled sludge was measured, and the oil removal rate was calculated to be 54.8%. After cleaning, the biodegradation rate of the residual macromolecular surfactant in the deoiled sludge reached 68.7% in the environment after 28 days.

[0072] This surfactant cannot achieve a reversible hydrophilic-hydrophobic structural transformation by introducing CO2 / N2 or adding dilute hydrochloric acid or dilute alkaline aqueous solution, and the prepared cleaning solution for cleaning oily sludge cannot achieve recycling efficiency close to that of the initial cleaning.

[0073] Comparative Example 3

[0074] This comparative example, based on Example 8, does not introduce diethylaminoethyl methacrylate and octadecyl methacrylate. It is prepared using acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and sodium p-styrenesulfonate as raw materials, with a mass ratio of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and sodium p-styrenesulfonate of 5:1:2. The surfactant is prepared using the same preparation process as in Example 8.

[0075] The surfactant was used to clean oily sludge, following the same cleaning process as in Example 8. After cleaning, solid-liquid separation was performed to obtain an oily emulsion and deoiled sludge. The petroleum hydrocarbon content in the deoiled sludge was measured, and the oil removal rate was calculated to be 47.4%. After cleaning, the biodegradation rate of the residual macromolecular surfactant in the deoiled sludge reached 59.3% in the environment after 28 days.

[0076] This surfactant cannot achieve a reversible hydrophilic-hydrophobic structural transformation by introducing CO2 / N2 or adding dilute hydrochloric acid or dilute alkaline aqueous solution, and the prepared cleaning solution for cleaning oily sludge cannot achieve recycling efficiency close to that of the initial cleaning.

[0077] Comparative Example 4

[0078] Preparation of macromolecular surfactant: Acrylamide, octadecyl methacrylate, and 2-vinylpyridine (2-VP) were dissolved in deionized water in a mass ratio of 5:1:2. After complete dissolution, the pH was adjusted to 7. 0.1 wt% ammonium persulfate aqueous solution was added, with the ratio of ammonium persulfate to the total mass of all monomers being 5:1000. N2 was bubbled through the system to remove oxygen for 30 min. Finally, the system was heated to 65 °C and stirred for 6 h. After the reaction was complete, the product was collected and dried at 40 °C for 48 h to obtain the macromolecular surfactant.

[0079] Cleaning of oily sludge: The macromolecular surfactant was dissolved in water to prepare a 0.3 wt% cleaning solution, which was then mixed with the oily sludge at a mass ratio of 20:1 and cleaned at 75°C for 120 min. After cleaning, solid-liquid separation was performed to obtain an oily emulsion and de-oiled sludge, respectively. The petroleum hydrocarbon content in the de-oiled sludge was measured, and the oil removal rate was calculated to be 72.9%. After cleaning, the biodegradation rate of the residual macromolecular surfactant in the de-oiled sludge reached 51.2% in the environment after 28 days.

[0080] This surfactant cannot achieve a reversible hydrophilic-hydrophobic structural transformation by introducing CO2 / N2 or adding dilute hydrochloric acid or dilute alkaline aqueous solution, and the prepared cleaning solution for cleaning oily sludge cannot achieve recycling efficiency close to that of the initial cleaning.

[0081] Comparative Example 5

[0082] Preparation of macromolecular surfactants: Acrylamide (main monomer), octadecyl methacrylate (hydrophobic monomer), 2-acrylamido-2-methylpropanesulfonic acid (AMPS) (hydrophilic monomer), and dimethylaminoethyl methacrylate (DMAEMA) (responsive monomer) were dissolved in deionized water in a mass ratio of 6:1:2:1. After complete dissolution, the pH was adjusted to 7. A 0.1 wt% aqueous solution of ammonium persulfate was added, with the ratio of ammonium persulfate to the total mass of all monomers being 5:1000. The system was then deoxygenated by purging with N2 for 30 min. Finally, the system was heated to 65 °C and stirred for 6 h. After the reaction was complete, the product was collected and dried at 40 °C for 48 h to obtain the macromolecular surfactant.

[0083] Cleaning of oily sludge: The macromolecular surfactant was dissolved in water to prepare a 0.3 wt% cleaning solution, which was then mixed with the oily sludge at a mass ratio of 20:1 and cleaned at 75 ℃ for 120 min. After cleaning, solid-liquid separation was performed to obtain an oily emulsion and de-oiled sludge, respectively. The petroleum hydrocarbon content in the de-oiled sludge was measured, and the oil removal rate was calculated to be 75.9%. After cleaning, the biodegradation rate of the residual macromolecular surfactant in the de-oiled sludge reached 53.7% in the environment after 28 days.

[0084] This surfactant cannot achieve a reversible hydrophilic-hydrophobic structural transition by introducing CO2 / N2 or adding dilute hydrochloric acid or dilute alkaline aqueous solutions. Therefore, the prepared cleaning solution for oily sludge cannot achieve near-initial cleaning efficiency for recycling. The reversible and dramatic hydrophilic-hydrophobic transition that originally occurred when the tertiary amine exists alone is suppressed, macroscopically manifested as a near-complete loss of pH responsiveness, failing to simultaneously meet the requirements of good cleaning effect and pH responsiveness.

[0085] Comparative Example 6

[0086] Preparation of macromolecular surfactants: Hydrophilic monomers methacrylic acid, hydrophobic monomers octadecyl methacrylate, and responsive monomers diethylaminoethyl methacrylate were dissolved in deionized water in a mass ratio of 5:1:2. After complete dissolution, the pH was adjusted to 7. A 0.1 wt% aqueous solution of ammonium persulfate was added, with the ratio of ammonium persulfate to the total mass of all monomers being 5:1000. The system was then deoxygenated by purging with N2 for 30 min. Finally, the system was heated to 65 °C and stirred for 6 h. After the reaction was complete, the product was collected and dried at 40 °C for 48 h to obtain the macromolecular surfactant.

[0087] Cleaning of oily sludge: The macromolecular surfactant was dissolved in water to prepare a 0.3 wt% cleaning solution, which was then mixed with the oily sludge at a mass ratio of 20:1 and cleaned at 75 ℃ for 120 min. After cleaning, solid-liquid separation was performed to obtain an oily emulsion and de-oiled sludge, respectively. The petroleum hydrocarbon content in the de-oiled sludge was measured, and the oil removal rate was calculated to be 65.7%. After cleaning, the biodegradation rate of the residual macromolecular surfactant in the de-oiled sludge reached 63.8% in the environment after 28 days.

[0088] This surfactant cannot achieve a reversible hydrophilic-hydrophobic structural transition by introducing CO2 / N2 or adding dilute hydrochloric acid or dilute alkaline aqueous solutions. Therefore, the prepared cleaning solution for cleaning oily sludge cannot achieve recycling efficiency close to that of the initial cleaning. The reversible and intense hydrophilic-hydrophobic transition that originally occurred when the tertiary amine exists alone is inhibited, and the pH responsiveness is essentially lost.

[0089] Comparative Example 7

[0090] Preparation of macromolecular surfactants: Hydrophilic monomer hydroxyethyl methacrylate, hydrophobic monomer octadecyl methacrylate, and responsive monomer diethylaminoethyl methacrylate were dissolved in deionized water in a mass ratio of 5:1:2. After complete dissolution, the pH was adjusted to 7. 0.1 wt% ammonium persulfate aqueous solution was added, with the ratio of ammonium persulfate to the total mass of all monomers being 5:1000. N2 was bubbled through the system to remove oxygen for 30 min. Finally, the system was heated to 65 °C and stirred for 6 h. After the reaction was complete, the product was collected and dried at 40 °C for 48 h to obtain the macromolecular surfactant.

[0091] Cleaning of oily sludge: The macromolecular surfactant was dissolved in water to prepare a 0.3 wt% cleaning solution, which was then mixed with the oily sludge at a mass ratio of 20:1 and cleaned at 75 ℃ for 120 min. After cleaning, solid-liquid separation was performed to obtain an oily emulsion and de-oiled sludge, respectively. The petroleum hydrocarbon content in the de-oiled sludge was measured, and the oil removal rate was calculated to be 69.4%. After cleaning, the biodegradation rate of the residual macromolecular surfactant in the de-oiled sludge reached 62.4% in the environment after 28 days.

[0092] This surfactant cannot achieve a reversible hydrophilic-hydrophobic structural transition by introducing CO2 / N2 or adding dilute hydrochloric acid or dilute alkaline solutions. Therefore, the prepared cleaning solution for cleaning oily sludge cannot achieve near-initial cleaning efficiency for recycling. The polymer cannot produce a significant and rapid hydrophilic-hydrophobic switch, and its pH responsiveness is significantly weakened or even disappears.

[0093] Comparative Example 8

[0094] Preparation of macromolecular surfactants: Hydrophilic monomers acrylamide, hydrophobic monomers methyleugenol, and responsive monomers diethylaminoethyl methacrylate were dissolved in deionized water in a mass ratio of 5:1:2. After complete dissolution, the pH was adjusted to 7. A 0.1 wt% aqueous solution of ammonium persulfate was added, with the ratio of ammonium persulfate to the total mass of all monomers being 5:1000. The system was then deoxygenated by purging with N2 for 30 min. Finally, the system was heated to 65 °C and stirred for 6 h. After the reaction was complete, the product was collected and dried at 40 °C for 48 h to obtain the macromolecular surfactant.

[0095] Cleaning of oily sludge: The macromolecular surfactant was dissolved in water to prepare a 0.3 wt% cleaning solution, which was then mixed with the oily sludge at a mass ratio of 20:1 and cleaned at 75 ℃ for 120 min. After cleaning, solid-liquid separation was performed to obtain an oily emulsion and de-oiled sludge, respectively. The petroleum hydrocarbon content in the de-oiled sludge was measured, and the oil removal rate was calculated to be 56.3%. After cleaning, the biodegradation rate of the residual macromolecular surfactant in the de-oiled sludge reached 58.6% in the environment after 28 days.

[0096] The oil-containing emulsion is demulsified by introducing CO2 into it to lower the pH to 6.5. The emulsion demulsifies into an oil layer and an aqueous layer containing macromolecular surfactants.

[0097] After demulsification and separation, the aqueous layer is regenerated and reused as a cleaning solution: After separating the oil phase, N2 is introduced into the aqueous layer containing macromolecular surfactants to raise the pH of the system to 8.5. Then, macromolecular surfactants are added to the resulting liquid at a dosage of 3 wt% of the initial dosage; water is added to restore the volume of the cleaning solution to the initial dosage, resulting in a cleaning solution that can be recycled for the treatment of oily sludge. However, the cleaning effect of the reused cleaning solution is poor; the oil removal rates of the 5th and 10th cleanings of the oily sludge are only 37.4% and 19.5%, respectively.

[0098] Comparative Example 9

[0099] Preparation of macromolecular surfactants: The main monomer N,N-dimethylacrylamide, the hydrophobic monomer octadecyl methacrylate, and the responsive monomer diethylaminoethyl methacrylate were dissolved in deionized water in a mass ratio of 5:1:2. After complete dissolution, the pH was adjusted to 7. A 0.1 wt% aqueous solution of ammonium persulfate was added, with the ratio of ammonium persulfate to the total mass of all monomers being 5:1000. N2 was introduced to deoxygenate the system for 30 min. Finally, the system was heated to 65 °C and stirred for 6 h. After the reaction was complete, the product was collected and dried at 40 °C for 48 h to obtain the macromolecular surfactant.

[0100] Cleaning of oily sludge: The macromolecular surfactant was dissolved in water to prepare a 0.3 wt% cleaning solution, which was then mixed with the oily sludge at a mass ratio of 20:1 and cleaned at 75°C for 120 min. After cleaning, solid-liquid separation was performed to obtain an oily emulsion and de-oiled sludge, respectively. The petroleum hydrocarbon content in the de-oiled sludge was measured, and the oil removal rate was calculated to be 61.6%. After cleaning, the biodegradation rate of the residual macromolecular surfactant in the de-oiled sludge in the environment was 59.4% at 28 days.

[0101] This surfactant cannot achieve a reversible hydrophilic-hydrophobic structural transformation by introducing CO2 / N2 or adding dilute hydrochloric acid or dilute alkaline aqueous solution, and the prepared cleaning solution for cleaning oily sludge cannot achieve recycling efficiency close to that of the initial cleaning.

[0102] Comparative Example 10

[0103] Preparation of macromolecular surfactant: Acrylamide, styrene (hydrophobic monomer), and diethylaminoethyl methacrylate (responsive monomer) were dissolved in deionized water in a mass ratio of 5:1:2. After complete dissolution, the pH was adjusted to 7. A 0.1 wt% aqueous solution of ammonium persulfate was added, with the ratio of ammonium persulfate to the total mass of all monomers being 5:1000. N2 was bubbled through the system to remove oxygen for 30 min. Finally, the system was heated to 65 °C and stirred for 6 h. After the reaction was complete, the product was collected and dried at 40 °C for 48 h to obtain the macromolecular surfactant.

[0104] Cleaning of oily sludge: The macromolecular surfactant was dissolved in water to prepare a 0.3 wt% cleaning solution, which was then mixed with the oily sludge at a mass ratio of 20:1 and cleaned at 75°C for 120 min. After cleaning, solid-liquid separation was performed to obtain an oily emulsion and de-oiled sludge, respectively. The petroleum hydrocarbon content in the de-oiled sludge was measured, and the oil removal rate was calculated to be 54.3%. After cleaning, the biodegradation rate of the residual macromolecular surfactant in the de-oiled sludge in the environment was 41.5% at 28 days.

[0105] This surfactant cannot achieve a reversible hydrophilic-hydrophobic structural transformation by introducing CO2 / N2 or adding dilute hydrochloric acid or dilute alkaline aqueous solution, and the prepared cleaning solution for cleaning oily sludge cannot achieve recycling efficiency close to that of the initial cleaning.

[0106] Table 2 lists the key parameters of different embodiments and comparative examples of the present invention, the oil removal efficiency (RE) of oily sludge, and the biodegradation efficiency (DE) of the surfactant remaining in the de-oiled sludge after 28 days.

[0107] Table 2. Comparison of surfactant preparation conditions and performance in the examples and comparative examples

[0108]

[0109] Any aspects not covered in this invention are applicable to existing technologies.

Claims

1. A recyclable and biodegradable macromolecular surfactant for cleaning oily sludge, characterized in that, The structural formula of the macromolecular surfactant used for cleaning oily sludge is: ， In the above structural formula, x = 200~250, y = 15~30, z = 50~60, m = 12~18, n = 1~2, and the total molecular weight is 10. 3 ~10 6 g / mol.

2. The recyclable and biodegradable macromolecular surfactant for cleaning oily sludge as described in claim 1, characterized in that, The preparation process of the macromolecular surfactant is as follows: acrylamide, long-chain alkyl methacrylate and tertiary amino-substituted methacrylate are dissolved in deionized water at a mass ratio of (1~5):1:(1~5), and the pH is adjusted to 5.5~8.5; then an initiator solution is added, and N2 is introduced for 20~30 min. The ratio of the amount of initiator to the total mass of all monomers is (1~20):1000; the total mass of all monomers is the total mass of acrylamide, long-chain alkyl methacrylate, and tertiary amino-substituted methacrylate. Finally, the system was heated to 40-85 °C and the reaction time was 4-8 h. After the reaction was completed, the product was collected and dried at 30-80 °C for 20-48 h to obtain a recyclable and biodegradable macromolecular surfactant for cleaning oily sludge.

3. The recyclable and biodegradable macromolecular surfactant for cleaning oily sludge as described in claim 2, characterized in that, The initiator is at least one of ammonium persulfate, potassium persulfate, or sodium persulfate; The long-chain alkyl methacrylate is at least one of dodecyl methacrylate, tetradecyl methacrylate, hexadecyl methacrylate, or octadecyl methacrylate. The tertiary amino-substituted methacrylate is at least one of dimethylaminoethyl methacrylate or diethylaminoethyl methacrylate.

4. The application of the recyclable and biodegradable macromolecular surfactant for cleaning oily sludge as described in claim 1 in the cleaning of oily sludge, characterized in that: The macromolecular surfactant was dissolved in water to prepare a cleaning solution of 0.1~0.5 wt%. The cleaning solution was injected into the oily sludge and stirred thoroughly. The oily sludge was cleaned at 40~90℃ for 60~120 min, wherein the mass ratio of the cleaning solution to the oily sludge was (5~20):

1. After cleaning, solid-liquid separation was performed to obtain an oily emulsion and deoiled sludge. The petroleum hydrocarbon content in the deoiled sludge was determined, and the oil removal rate was calculated. The oil removal rate of the macromolecular surfactant on the oily sludge was greater than 70%. The oil-containing emulsion is demulsified and separated by the following process: CO2 is introduced into the oil-containing emulsion or a dilute hydrochloric acid aqueous solution is added to lower the pH of the system to 4-6.9, and the emulsion is demulsified into an oil layer and an aqueous layer containing the macromolecular surfactant. After demulsification and separation, the aqueous layer is regenerated and reused using a washing solution. Specifically, after separating the oil phase, N2 is introduced into the aqueous layer containing the macromolecular surfactant, or a dilute alkaline solution is added, to raise the pH of the system to 7-9. Then, the macromolecular surfactant is added to the system at a rate of 1-5 wt% of the initial dosage. Then add water to restore the volume of the cleaning solution to the initial amount, resulting in a cleaning solution that can be recycled for the treatment of oily sludge.

5. The application as described in claim 4, characterized in that, After the oily sludge was washed, the degradation rate of the macromolecular surfactants remaining in the deoiled sludge in the environment was greater than 70% at 28 days.

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