A switchable microemulsion, method of use and method of oily sludge treatment

Abstract

The application provides a switch type microemulsion, a use method and an oily sludge treatment method. The switch type microemulsion comprises low aliphatic acid, a surfactant, a co-surfactant, an inorganic carbonate, a graphene modified amine substance and water. The switch type microemulsion configured on the basis of the switch type solvent low aliphatic acid has the advantages of small toxicity, high flash point, recyclability and the like. Compared with the use of low aliphatic acid directly as the switch type solvent, the switch type microemulsion has lower cost and better cleaning effect. Moreover, the switch type microemulsion introduces the graphene modified material to realize stripping of stubborn oil phases in the oily sludge, and further improves the cleaning effect.

Description

Technical Field

[0001] This application relates to the field of switchable microemulsion technology, and in particular to a switchable microemulsion, its application method, and a method for treating oily sludge. Background Technology

[0002] Oily sludge, or simply oily sludge, refers to sludge mixed with heavy oils such as crude oil, refined oil, and residual oil. It is a byproduct of petroleum production and one of the main pollutants from the petroleum and petrochemical industries. With increasing environmental awareness and rising oil prices, the treatment of oily sludge pollution and the recovery of petroleum resources have attracted widespread attention. Currently, the treatment of oily sludge utilizes both traditional and novel technologies.

[0003] Traditional treatment technologies include thermochemical cleaning and extraction. Thermochemical cleaning involves adding a certain proportion of hot water and chemical agents to oily sludge. Through high-speed stirring and the emulsification and oxidation effects of the chemicals, crude oil is washed and detached from the sludge surface to achieve the cleaning purpose. This method often generates a large amount of wastewater and has limited cleaning effectiveness, proving ineffective for difficult-to-treat oily sludge such as refinery sludge. Extraction, based on the principle of "like dissolves like," uses oily solvents to extract crude oil from oily sludge. However, this method has high processing costs, and the oily solvents are not easily recycled.

[0004] Due to various limitations of traditional processing technologies, novel processing technologies, especially switch-type microemulsion extraction, have been developed. Microemulsions are thermodynamically stable, isotropic, and transparent or semi-transparent dispersion systems that spontaneously form under certain conditions. Microemulsion precursors are miscible with oil and water, greatly reducing the interfacial tension between oil and water, enhancing the fluidity of hydrophobic organic matter, and increasing its solubility, which is beneficial for the removal of oil from mud and sand.

[0005] A switch-type microemulsion extraction method uses organic amines as the oil phase solvent, and prepares microemulsions with surfactants and water for oily sludge extraction. The microemulsions are recycled based on a CO2 response. Publication number CN114621781A discloses "CO2-responsive microemulsions and their preparation methods and methods for treating oily drill cuttings," which uses anionic surfactants, co-surfactants, and an oil phase in water to prepare microemulsions, achieving base oil recovery through a CO2 response. However, the oil phase of this microemulsion is composed of highly toxic and odorous organic amines, which can easily cause secondary pollution and harm the health of operators. Furthermore, its low flash point poses a risk of explosion. Summary of the Invention

[0006] This application provides a switchable microemulsion, a method of application, and a method for treating oily sludge, in order to at least solve the above-mentioned technical problems existing in the prior art.

[0007] According to a first aspect of this application, a switchable microemulsion is provided, comprising: lower fatty acids, surfactants, co-surfactants, inorganic carbonates, graphene-modified amines, and water.

[0008] In one embodiment, the co-surfactant includes an alkaline co-surfactant and an acidic co-surfactant; the molar ratio of the lower fatty acid, alkaline co-surfactant, acidic co-surfactant, and inorganic carbonate is 1:(0.5-1.5):(0.5-1.5):(0.5-1.5); the mass ratio of the lower fatty acid to the surfactant is 1:(0.1-1.0); the water accounts for 50-95% of the total mass; and the pH value of the switch-type microemulsion is 5.6-6.6.

[0009] In one embodiment, the graphene-modified amine is one or more of graphene-modified polyether amine and graphene-modified polyol amine; the amount of graphene-modified amine added corresponds to the amount of alkaline co-surfactant, and the ratio of the number of amino groups in the graphene-modified amine to the number of amino groups in the alkaline co-surfactant is (0-1):10.

[0010] In one embodiment, the switchable microemulsion is converted into an aqueous dispersion by adding a first switchable substance; the aqueous dispersion is converted into a switchable microemulsion by adding a second switchable substance.

[0011] In one embodiment, the aqueous dispersion solution is alkaline and includes lower fatty acid ions, cations corresponding to inorganic carbonates, surfactants, acidic co-surfactants, alkaline co-surfactants, graphene-modified amines, and water; the first switching substance is a soluble calcium compound; and the second switching substance is carbon dioxide.

[0012] In one embodiment, the soluble calcium compound is one or more of calcium oxide and calcium hydroxide; the inorganic carbonate is one or more of ammonium bicarbonate, sodium bicarbonate, and potassium bicarbonate.

[0013] In one embodiment, the number of carbon atoms in the carbon chain of the lower fatty acid does not exceed ten; the surfactant is an anionic surfactant.

[0014] In one embodiment, the alkaline co-surfactant is one or more of alcohol amines and ether amines; the acidic co-surfactant is a polycarboxylic organic acid or its anhydride.

[0015] According to a second aspect of this application, a method for using a switchable microemulsion is provided, comprising: dissolving a low-grade fatty acid, a surfactant, a co-surfactant, an inorganic carbonate, and a graphene-modified amine in water to form a switchable microemulsion; when it is necessary to convert the switchable microemulsion into an aqueous dispersion, adding a first switchable substance to the switchable microemulsion to convert the switchable microemulsion into an aqueous dispersion and generate calcium carbonate precipitate; when it is necessary to convert the aqueous dispersion into the switchable microemulsion, adding a second switchable substance to the aqueous dispersion to convert the aqueous dispersion into a switchable microemulsion.

[0016] According to a third aspect of this application, a method for treating oily sludge based on a switchable microemulsion is provided, comprising: mixing oily sludge with a switchable microemulsion to achieve oil and sludge separation, obtaining an oil-containing microemulsion extract phase and forming a bottom sludge precipitate, wherein the switchable microemulsion comprises lower fatty acids, surfactants, co-surfactants, inorganic carbonates, graphene-modified amines, and water; adding a first switchable substance to the microemulsion extract phase, wherein the microemulsion in the microemulsion extract phase is converted into an aqueous dispersion solution and calcium carbonate precipitate is generated, at which point the oil phase is separated from the aqueous dispersion solution, resulting in sequentially layered oil phase, aqueous dispersion solution, and mixed precipitate, wherein the mixed precipitate comprises bottom sludge precipitate and calcium carbonate precipitate; separating the oil phase, aqueous dispersion solution, and mixed precipitate, recovering the oil phase, and adding a second switchable substance to the aqueous dispersion solution to convert the aqueous dispersion solution back into a switchable microemulsion.

[0017] The switchable microemulsion, its application method, and the method for treating oily sludge provided in this application have the following advantages:

[0018] 1. Switching microemulsions formulated based on lower fatty acids as switching solvents have the advantages of low toxicity, high flash point, and recyclability; at the same time, compared with using lower fatty acids directly as switching solvents, the cost is lower and the cleaning ability is improved.

[0019] 2. This switch-type microemulsion uses anionic surfactants. Since anionic surfactants have poor emulsification effects, they will not emulsify the oil phase in the aqueous dispersion state. The oil and water phases are easy to separate, improving the oil phase recovery rate. At the same time, the oil content in the aqueous dispersion is extremely low, which is beneficial for maintaining the cleaning ability when the switch-type emulsion is recycled.

[0020] 3. Adding inorganic carbonates enables the switchable microemulsion to switch between CO2 and quicklime. The resulting calcium carbonate precipitate acts as an additional solid phase generated during the cleaning process, which can dilute the bottom mud, reduce the overall residual oil rate, and improve the cleaning effect. At the same time, it can achieve carbon dioxide sequestration and help carbon neutralization.

[0021] 4. The introduction of graphene-modified materials into the switch-type microemulsion enables the removal of stubborn oil phases in oily sludge, further enhancing the cleaning ability.

[0022] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this application, nor is it intended to limit the scope of this application. Other features of this application will become readily apparent from the following description. Attached Figure Description

[0023] The above and other objects, features, and advantages of exemplary embodiments of this application will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings. Several embodiments of this application are illustrated in the drawings by way of example and not limitation, in which:

[0024] In the accompanying drawings, the same or corresponding reference numerals indicate the same or corresponding parts.

[0025] Figure 1 The diagram illustrates the implementation flow of a method for using a switchable microemulsion according to an embodiment of this application. Detailed Implementation

[0026] To make the objectives, features, and advantages of this application more apparent and understandable, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] According to a first aspect of this application, a switchable microemulsion is provided, comprising: lower fatty acids, surfactants, co-surfactants, inorganic carbonates, graphene-modified amines, and water.

[0028] This application provides a switchable microemulsion, which is a solution prepared with a switchable solvent, lower fatty acids. The switchable microemulsion has the advantages of low toxicity, high flash point, and recyclability. At the same time, compared with using lower fatty acids directly as a switchable solvent, it has lower cost and better cleaning effect. Furthermore, the switchable microemulsion introduces graphene-modified materials to remove stubborn oil phases in oily sludge, thereby improving the cleaning effect.

[0029] This application provides a switchable microemulsion that uses a first and a second switching substance as a switch, enabling the switching between the microemulsion and the aqueous dispersion solution. It is suitable for treating contaminants with both oil and solid phases, separating the oil and solid phases. Furthermore, by switching the switching substances, the switchable microemulsion can be recovered, achieving its recycling. Contaminants include oily sludge and oily mechanical parts.

[0030] In the process of treating pollutants, firstly, under acidic conditions, the lower fatty acids in the microemulsion can extract the oil phase, achieving separation of the solid and oil phases. At this time, the switch-type microemulsion is acidic, and graphene-modified materials are introduced to remove the stubborn oil phase from the oily sludge, improving the cleaning effect. Then, the first switching substance, soluble calcium, is added. After the soluble calcium dissolves in the switch-type microemulsion, the pH of the system changes from acidic to alkaline. The oil-soluble lower fatty acids are converted into water-soluble lower fatty acid ions. Simultaneously, calcium ions can react with carbonate ions to form calcium carbonate precipitate. The switch-type microemulsion then switches to an aqueous dispersion solution, causing the oil phase of the pollutants to precipitate from the aqueous dispersion solution. Because the density of the oil phase is less than that of the aqueous phase, the oil phase floats on the aqueous phase, while the solid phase settles at the bottom, achieving separation of the oil and solid phases of the oily pollutants.

[0031] Next, the aqueous dispersion is recovered, and a second switching substance, carbon dioxide, is added to it. Carbon dioxide combines with water to form bicarbonate ions, which lowers the pH to acidic. At this point, water-soluble lower fatty acid ions are converted into oil-soluble lower fatty acids, and the aqueous dispersion is switched to a microemulsion, realizing the regeneration of the switch-type microemulsion. That is, the microemulsion can be used again to treat oily pollutants.

[0032] The switchable microemulsion provided in this application utilizes the characteristics of a switchable microemulsion formed by lower fatty acids in an acidic environment. In an alkaline environment, it has the characteristics of being water-soluble and losing compatibility with oil, thereby achieving the extraction and separation of the oil phase of contaminants. Furthermore, the introduction of graphene-modified materials enables the stripping of stubborn oil phases from oily sludge, improving the cleaning effect.

[0033] Microemulsions are formed by mixing surfactants, co-surfactants, inorganic carbonates, graphene-modified amines, and water with lower fatty acids. Compared to pure lower fatty acid solvents, microemulsions exhibit better extraction performance on the oil phase. Furthermore, since microemulsions are predominantly water, raw material costs are reduced. The combination of surfactants and co-surfactants results in homogeneous and stable microemulsions. These microemulsions are miscible with both water and oil.

[0034] The inorganic carbonate is a soluble inorganic carbonate with both cations and anions that can dissolve in the switch-type microemulsion. When the first switch substance is added, the cations formed after the first switch substance dissolves in the switch-type microemulsion react with the anions of the inorganic carbonate to form a precipitate. Simultaneously, the formation of the precipitate promotes the dissolution of the first switch substance, generating a large number of hydroxide ions. These hydroxide ions react with oil-soluble lower fatty acids to form water-soluble lower fatty acid ions, transforming the microemulsion into an aqueous dispersion. When the second switch substance is added to the aqueous dispersion, the second switch substance reacts with water to form carbonic acid. Carbonic acid is more acidic than lower fatty acids, converting the lower fatty acid ions into lower fatty acids, while simultaneously generating bicarbonate ions. The aqueous dispersion then transforms into a microemulsion. In subsequent switch cycles, the first switch substance is added again to form calcium carbonate precipitate, which is equivalent to absorbing carbon dioxide and converting gaseous carbon dioxide into solid calcium carbonate, achieving carbon dioxide sequestration, contributing to carbon neutrality, and making it more environmentally friendly.

[0035] In one embodiment, the switchable microemulsion and the aqueous dispersion further contain graphene-modified amines, which are one or more of graphene-modified polyether amines and graphene-modified polyol amines; the amount of graphene-modified amines added corresponds to the amount of alkaline co-surfactant, and the ratio of the number of amino groups in the graphene-modified amines to the number of amino groups in the alkaline co-surfactant is (0-1):10.

[0036] The amount of graphene-modified amine added can correspond to the amount of alkaline co-surfactant added. Calculated in molar ratio, the number of amino groups in the graphene-modified amine is defined as the unit of calculation, and the number of amino groups in the alkaline co-surfactant is defined as the unit of calculation. The ratio of the number of amino groups in the graphene-modified amine to the number of amino groups in the alkaline co-surfactant is (0-1):10, preferably with the proportion of graphene-modified amine not exceeding one-tenth of the alkaline co-surfactant.

[0037] The following provides a method for preparing graphene-modified polyetheramine:

[0038] Add 1 part graphene oxide (GO) to 10-1000 parts polyetheramine D230, stir and heat to 50-80℃, and continue stirring at this temperature for 6-8 hours to obtain graphene-modified polyetheramine. For preparing other graphene-modified amines, the reaction temperature, reaction time, and other reaction parameters can be adjusted based on the target amine, which will not be elaborated further.

[0039] The following provides specific preparation scenarios for graphene-modified polyetheramines.

[0040] Add 1g of GO to 50g of polyetheramine D230, stir and heat to 60℃, and continue stirring at this temperature for 8 hours to obtain graphene-modified polyetheramine.

[0041] In one embodiment, the number of carbon atoms in the carbon chain of the lower fatty acid does not exceed ten carbon atoms.

[0042] Lower fatty acids are liquid at room temperature. Formulating them into microemulsions is simpler and less costly compared to other substances that can switch between water-soluble and oil-soluble states. Therefore, this application does not limit the chain structure of the lower fatty acids; they can be chain-like or cyclic fatty acids, as long as the carbon chain of the lower fatty acid does not exceed ten carbon atoms. The lower fatty acids can be selected based on the actual oil content of the oil-containing contaminants, choosing one or more of the following: hexanoic acid, heptanoic acid, octanoic acid, isooctanoic acid, nonanoic acid, isononanoic acid, decanoic acid, and neodecanoic acid.

[0043] In one embodiment, the surfactant is an anionic surfactant.

[0044] Anionic surfactants have poor emulsifying ability, but when a switchable microemulsion is converted into an aqueous dispersion, it can facilitate the separation of the oil and aqueous phases. Anionic surfactants can be selected from one or more of the following: sodium α-alkenyl sulfonate and its copolymers, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, triethanolamine dodecylbenzene sulfonate, secondary alkyl sulfonate, sodium dodecyl diphenyl ether disulfonate, fatty alcohol polyoxyethylene ether sulfate, fatty alcohol polyoxyethylene ether sulfonate, alkylphenol polyoxyethylene ether carboxylate, and fatty alcohol polyoxyethylene ether carboxylate.

[0045] In one embodiment, the co-surfactant includes basic co-surfactants and acidic co-surfactants; the basic co-surfactant is an amino-based co-surfactant, which is at least one of an alcoholamine or an etheramine co-surfactant. The acidic co-surfactant is a small-molecule organic acid co-surfactant, which is a polycarboxylic acid or its anhydride.

[0046] Co-surfactants include basic co-surfactants and acidic co-surfactants. By combining the two co-surfactants, the microemulsion can be kept stable and can be diluted with water in any way, simplifying the preparation process of switchable microemulsions.

[0047] Among them, the alkanolamine or etheramine cosurfactant is selected from one or more of the following: monoethanolamine, diethanolamine, triethanolamine, N-(2-hydroxyethyl)ethylenediamine, N,N'-bis(2-hydroxyethyl)ethylenediamine, N,N,N',N'-tetra(2-hydroxyethyl)ethylenediamine, polyetheramine D230, polyetheramine EDR-100, polyetheramine THF-100, and polyetheramine T-403.

[0048] The small molecule organic acid co-surfactants are selected from one or more of the following: oxalic acid, malonic acid, fumaric acid, maleic acid, maleic anhydride, succinic acid, succinic anhydride, glutaric acid, glutaric anhydride, citric acid, malic acid, and tartaric acid.

[0049] Taking decanoic acid, sodium bicarbonate, malonic acid, and ethanolamine as examples

[0050] The reaction process is as follows:

[0051]

[0052] The reaction involves malonic acid and ethanolamine acting as co-surfactants to react with each other to generate an amphiphilic substance that promotes the formation of microemulsions.

[0053]

[0054] This reaction is a switching process with decanoic acid as the lower fatty acid. It should be understood that the soluble components of the switch-type microemulsion and aqueous dispersion exist in the system in ionic form, and the actual reaction is not limited to the above equation.

[0055] In one embodiment, the molar ratio of lower fatty acids, alkaline co-surfactants, and inorganic carbonates is 1:(0.5-1.5):(0.5-1.5); the amount of acidic co-surfactants added corresponds to the pH value of the switch-type microemulsion, and the pH value of the microemulsion is 5.6-6.6.

[0056] This application embodiment can use specific component ratios to ensure the stability of the switchable microemulsion. Specifically, based on the molar ratio, the calculation is defined as the number of carboxylate groups, based on the presence of carboxyl groups in lower fatty acids; the calculation is also defined as the number of carboxylate groups, based on the presence of polycarboxylic organic acids or their anhydrides in acidic co-surfactants; and the calculation is defined as the number of amino groups, based on the presence of amino groups in basic co-surfactants.

[0057] The molar ratio of lower fatty acids: acidic co-surfactant: basic co-surfactant is 1:(0.5-1.5):(0.5-1.5); preferably 1:(0.95-1.05):(1.0-1.1). Alternatively, during the preparation of the switch-type microemulsion, the acidic co-surfactant is added last to adjust the pH to acidic. In this case, the actual amount of acidic co-surfactant added is determined based on the pH value of the switch-type microemulsion. The pH value of the microemulsion is adjusted to 5.6-6.6, preferably 5.8-6.4.

[0058] In one embodiment, the mass ratio of lower fatty acids to surfactants is 1:(0.1 to 1.0).

[0059] This application embodiment can use specific component ratios to ensure the stability of the switchable microemulsion. The preferred mass ratio of lower fatty acids to surfactants is 1:(0.1~0.6).

[0060] The remainder is water, which accounts for 50-95% of the total mass according to the mass ratio. Because the dispersant contains a large amount of water, the cost is low.

[0061] In one embodiment, the soluble calcium compound is at least one of calcium oxide and calcium hydroxide.

[0062] In the selection of soluble calcium compounds, at least one of calcium oxide and calcium hydroxide can be chosen. As the first switching substance, it can adjust the pH of the switching microemulsion and react with carbonates to form calcium carbonate precipitate.

[0063] In one embodiment, the inorganic carbonate is a bicarbonate, such as ammonium bicarbonate, sodium bicarbonate, or potassium bicarbonate. Bicarbonates do not react with fatty acid ions.

[0064] According to a second aspect of this application, a method for using a switchable microemulsion is provided, comprising: step 101, dissolving a lower fatty acid, a surfactant, a co-surfactant, an inorganic carbonate, and a graphene-modified amine in water to form a switchable microemulsion; step 102, when it is necessary to convert the switchable microemulsion into an aqueous dispersion, adding a first switch substance to the switchable microemulsion to convert the switchable microemulsion into an aqueous dispersion and generating calcium carbonate precipitate; wherein, the first switch substance is a soluble calcium compound, and the aqueous dispersion includes a lower fatty acid ion, a cation corresponding to the inorganic carbonate, a surfactant, a co-surfactant, a graphene-modified amine, and water; step 103, when it is necessary to convert the aqueous dispersion into a switchable microemulsion, adding a second switch substance to the aqueous dispersion to convert the aqueous dispersion into a microemulsion; wherein, the second switch substance is carbon dioxide.

[0065] Operations 101 to 103 describe the conversion process of the dispersion system of the switch-type microemulsion, explained in conjunction with the treatment of oily contaminants. First, under acidic conditions, the switch-type microemulsion, by its very nature, can extract the oil phase, achieving separation of the solid and oil phases. Then, a first switching substance, a soluble calcium compound, is added. After the soluble calcium compound dissolves in the switch-type microemulsion, calcium ions react with carbonate ions to form calcium carbonate precipitate. Simultaneously, the formation of the precipitate promotes the dissolution of the first switching substance, generating a large number of hydroxide ions, causing the pH of the switch-type microemulsion to change from acidic to alkaline. These hydroxide ions then react with lower fatty acids to form lower fatty acid ions. These lower fatty acid ions are water-soluble, forming an aqueous dispersion solution. This aqueous dispersion solution loses its ability to dissolve the oil phase of the contaminant, causing the oil phase of the contaminant to precipitate from the aqueous dispersion solution. Since the density of the oil phase is less than that of the aqueous phase, the oil phase floats on top of the aqueous phase, while the solid phase settles below it, achieving separation of the oil and solid phases of the oily contaminant.

[0066] Next, the aqueous dispersion is recovered, and a second switching substance, carbon dioxide, is added to it. Carbon dioxide combines with water to form acid anions, which lowers the pH to acidic. At this point, the lower fatty acid anions are converted into lower fatty acids, and the aqueous dispersion is switched to a switch-type microemulsion, realizing the regeneration of the switch-type microemulsion. That is, the newly formed switch-type microemulsion can be used to treat oily pollutants again.

[0067] It should be added that, when a switchable microemulsion provided in this application embodiment contains graphene-modified amines, a method of using the switchable microemulsion includes:

[0068] First, low fatty acids, surfactants, co-surfactants, inorganic carbonates, and graphene-modified amines are dissolved in water to form a switch-type microemulsion.

[0069] Then, when it is necessary to convert the switch-type microemulsion into an aqueous dispersion, a first switch substance is added to the switch-type microemulsion to convert it into an aqueous dispersion and generate calcium carbonate precipitate; wherein, the first switch substance is a soluble calcium compound, and the aqueous dispersion includes lower fatty acid ions, cations corresponding to inorganic carbonates, surfactants, co-surfactants, graphene-modified amines, and water;

[0070] Subsequently, when it is necessary to convert the aqueous dispersion into a switchable microemulsion, a second switchable substance is added to the aqueous dispersion to convert it into a microemulsion; wherein, the second switchable substance is carbon dioxide.

[0071] Its effect is to better peel off stubborn oil phases, such as gum asphalt. The remaining operations and effects are consistent with the above implementation method and will not be repeated.

[0072] According to a third aspect of this application, a method for treating oily sludge based on a switchable microemulsion is provided, comprising: step 201, mixing oily sludge with a switchable microemulsion, such that the oil phase of the oily sludge combines with the switchable microemulsion to form a sediment precipitate, wherein the switchable microemulsion comprises lower fatty acids, surfactants, co-surfactants, inorganic carbonates, graphene-modified amines, and water; and step 202, adding a first switchable substance to the switchable microemulsion, such that the switchable microemulsion is converted into an aqueous dispersion solution and calcium carbonate precipitate is generated, wherein the oil phase of the oily sludge combines with the water... The dispersion solution is separated to obtain an oil phase, an aqueous dispersion solution, and a mixed precipitate that are sequentially separated. The mixed precipitate includes sediment precipitate and calcium carbonate precipitate. The first switching substance is a soluble calcium compound. The aqueous dispersion solution includes lower fatty acid ions, cations corresponding to inorganic carbonates, surfactants, co-surfactants, graphene-modified amines, and water. In operation 203, the oil phase, aqueous dispersion solution, and mixed precipitate of the oily sludge are separated. A second switching substance is added to the aqueous dispersion solution to convert it back into a microemulsion. The second switching substance is carbon dioxide.

[0073] See Figure 1 When a switchable microemulsion provided in this application contains graphene-modified amines, a method for treating oily sludge based on the switchable microemulsion includes:

[0074] First, oily sludge is mixed with a switch-type microemulsion, so that the oil phase of the oily sludge combines with the switch-type microemulsion and forms bottom sludge sediment. The switch-type microemulsion includes lower fatty acids, surfactants, co-surfactants, inorganic carbonates, graphene-modified amines and water.

[0075] Then, a first switching substance is added to the switch-type microemulsion to convert it into an aqueous dispersion solution and generate calcium carbonate precipitate. The oil phase of the oily sludge is separated from the aqueous dispersion solution, resulting in sequentially layered oil phase, aqueous dispersion solution, and mixed precipitate. The mixed precipitate includes bottom sludge precipitate and calcium carbonate precipitate. The first switching substance is a soluble calcium compound, and the aqueous dispersion solution includes lower fatty acid ions, cations corresponding to inorganic carbonates, surfactants, co-surfactants, graphene-modified amines, and water.

[0076] Next, the oil phase, aqueous dispersion, and mixed precipitate of the oily sludge are separated. A second switching substance is added to the aqueous dispersion to convert the aqueous dispersion back into a microemulsion. The second switching substance is carbon dioxide.

[0077] To facilitate a further understanding of the above implementation scenarios, a specific implementation scenario is provided below: a method for treating oily sludge based on switchable microemulsions, comprising:

[0078] First, the oily sludge sample is mixed with a switch-type microemulsion in a microemulsion state at a volume ratio of 1:(2-5). The mixture can be heated to 60-70°C in a container and stirred for 0.5-1.5 hours to achieve thorough mixing. Then, it is allowed to stand for 10-30 minutes to allow the microemulsion to fully extract the oil phase from the oily sludge sample.

[0079] Then, add a certain amount of quicklime or hydrated lime, adjust the pH value to 7.5-8.5, and continue stirring for 10-30 minutes to carry out the on / off reaction;

[0080] Then, the three-phase separation of oil, water and solid phases is achieved by centrifugation. The oil phase is recovered to obtain usable oil resources. The solid phase is separated to obtain solid waste that meets national standards. The water phase is recovered and converted into a reusable microemulsion in a microemulsion state using carbon dioxide.

[0081] The following provides specific implementation scenarios as examples.

[0082] Example 1

[0083] Switchable microemulsions include: octanoic acid, sodium bicarbonate, malonic acid, D230, graphene-modified polyetheramine, and SDS.

[0084] Preparation method: Dissolve 28.84g SDS, 100g D230, 15g graphene-modified polyetheramine and 84g sodium bicarbonate in 1696.16g water, add 144.2g octanoic acid and stir evenly, then add 52g malonic acid and keep stirring until the malonic acid is completely dissolved to obtain a switch-type microemulsion. At this time, the pH value of the switch-type microemulsion is 6.0.

[0085] Example 2

[0086] Switchable microemulsions include: octanoic acid, sodium bicarbonate, malonic acid, D230, graphene-modified polyetheramine, and AOS.

[0087] Preparation method: Dissolve 28.84g AOS, 100g D230, 15g graphene-modified polyetheramine and 84g sodium bicarbonate in 1696.16g water, add 144.2g octanoic acid and stir evenly, then add 52g malonic acid and keep stirring until the malonic acid is completely dissolved to obtain the switch-type microemulsion. At this time, the pH value of the switch-type microemulsion is 6.1.

[0088] Example 3

[0089] Switchable microemulsions include: octanoic acid, sodium bicarbonate, malonic acid, D230, graphene-modified polyetheramine, and AES.

[0090] Preparation method: Dissolve 28.84g AES, 100g D230, 15g graphene-modified polyetheramine and 84g sodium bicarbonate in 1696.16g water, add 144.2g octanoic acid and stir evenly, then add 52g malonic acid and keep stirring until the malonic acid is completely dissolved to obtain the switch-type microemulsion. At this time, the pH value of the switch-type microemulsion is 5.9.

[0091] Example 4

[0092] Switchable microemulsions include: octanoic acid, sodium bicarbonate, malonic acid, D230, graphene-modified polyetheramine, and SLES.

[0093] Preparation method: Dissolve 28.84g SLES, 100g D230, 15g graphene-modified polyetheramine and 84g sodium bicarbonate in 1696.16g water, add 144.2g octanoic acid and stir evenly, then add 52g malonic acid and keep stirring until the malonic acid is completely dissolved to obtain the switch-type microemulsion. At this time, the pH value of the switch-type microemulsion is 5.9.

[0094] Example 5

[0095] Switchable microemulsions include: hexanoic acid, sodium bicarbonate, malonic acid, D230, graphene-modified polyetheramine, and SLES.

[0096] Preparation method: Dissolve 23.24g SLES, 100g D230, 15g graphene-modified polyetheramine and 84g sodium bicarbonate in 1561.76g water, add 116.2g hexanoic acid and stir evenly, then add 52g malonic acid and keep stirring until the malonic acid is completely dissolved to obtain the switch-type microemulsion. At this time, the pH value of the switch-type microemulsion is 5.7.

[0097] Example 6

[0098] Switchable microemulsions include: heptanoic acid, sodium bicarbonate, malonic acid, D230, graphene-modified polyetheramine, and SLES.

[0099] Preparation method: Dissolve 26.04g SLES, 100g D230, 15g graphene-modified polyetheramine and 84g sodium bicarbonate in 1628.96g water, add 130.2g n-heptanoic acid and stir evenly, then add 52g malonic acid and keep stirring until the malonic acid is completely dissolved to obtain the switch-type microemulsion. At this time, the pH value of the switch-type microemulsion is 5.8.

[0100] Example 7

[0101] Switchable microemulsions include: nonanoic acid, sodium bicarbonate, malonic acid, D230, graphene-modified polyetheramine, and SLES.

[0102] Preparation method: Dissolve 31.64g SLES, 100g D230, 15g graphene-modified polyetheramine and 84g sodium bicarbonate in 1763.36g water, add 158.2g nonanoic acid and stir evenly, then add 52g malonic acid and keep stirring until the malonic acid is completely dissolved to obtain the switch-type microemulsion. At this time, the pH value of the switch-type microemulsion is 6.0.

[0103] Example 8

[0104] Switchable microemulsions include: decanoic acid, sodium bicarbonate, malonic acid, D230, graphene-modified polyetheramine, and SLES.

[0105] Preparation method: Dissolve 34.46g SLES, 100g D230, 15g graphene-modified polyetheramine and 84g sodium bicarbonate in 1831.04g water, add 172.3g n-decanoic acid and stir evenly, then add 52g malonic acid and keep stirring until the malonic acid is completely dissolved to obtain the switch-type microemulsion. At this time, the pH value of the switch-type microemulsion is 6.1.

[0106] Comparative Example 1

[0107] Switchable microemulsions include: octanoic acid, sodium bicarbonate, malonic acid, D230, and SDS.

[0108] Preparation method: Dissolve 28.84g SDS, 115g D230 and 84g sodium bicarbonate in 1696.16g water, add 144.2g octanoic acid and stir evenly, then add 52g malonic acid and keep stirring until the malonic acid is completely dissolved to obtain the switch-type microemulsion. At this time, the pH value of the switch-type microemulsion is 6.0.

[0109] Comparative Example 2

[0110] Pure caprylic acid, without any other substances.

[0111] Comparative Example 3

[0112] D60 solvent oil (hydrocarbons, solvent that is not renewable or recyclable).

[0113] test

[0114] 1. Simulated oil test.

[0115] Using Comparative Example 1 as an example, the microemulsion can be mixed with crude oil or white oil to form a homogeneous phase. After adding a certain amount of quicklime, the oil, water, and solid components can be separated. When a certain amount of carbon dioxide is introduced, the microemulsion is regenerated and a homogeneous phase is formed again.

[0116] 2. Oily sludge cleaning test

[0117] Test subject:

[0118] Using refinery tank bottom sludge as a sample, the oil content of the treated bottom sludge should be <8%.

[0119] The microemulsion or solvent dispersion systems of the corresponding examples and comparative examples were mixed at a mass ratio of 1:3. Three samples of each example and comparative example were washed and labeled as Sample 1, Sample 2 and Sample 3. The washing temperature was 70°C and the samples were magnetically stirred for 1 hour. After centrifugation, the bottom mud was taken, dried and ground into powder.

[0120] The residual oil content of the powdery sediment was determined according to the standard "Determination of Petroleum in Soil - Infrared Spectrophotometry" (HJ1051-2019).

[0121] The measurement results are as follows:

[0122]

[0123]

[0124] As shown in the table above, the switchable microemulsion provided in this application embodiment can clean oily sludge and fully meet the manufacturer's requirement that the oil content of the treated sludge be <8%.

[0125] As can be seen from the comparison of Examples 1-8 with Comparative Example 1, the introduction of graphene-modified polyetheramine also significantly improves the cleaning effect;

[0126] As can be seen from Examples 1-8 and Comparative Example 3, the cleaning effect is comparable to that of the non-recyclable D60 solvent (which almost reaches the limit of cleaning effect), indicating that the microemulsion has an excellent cleaning effect.

[0127] 3. Secondary cleaning test

[0128] To verify that graphene-modified polyetheramine can improve the cleaning effect, after one cleaning in Comparative Example 1, a second cleaning was performed to compare the cleaning effects of Comparative Example 1 and Example 1. The cleaning method was as follows:

[0129] The powdered sediment obtained in Comparative Example 1 was mixed again with the switch-type microemulsions of Comparative Example 1 and Example 1 at a mass ratio of 1:3. The mixture was stirred magnetically at 70°C for 1 hour. After centrifugation, the sediment was collected, dried, and ground into powdered sediment.

[0130] The residual oil content of the powdery sediment was determined according to the standard "Determination of Petroleum in Soil - Infrared Spectrophotometry" (HJ1051-2019).

[0131] The measurement results are as follows:

[0132] Example 1 3.25 Comparative Example 1 5.17

[0133] As shown in the table above, the introduction of graphene-modified polyetheramine has a cleaning effect on stubborn oil phases.

[0134] 4. Circulation cleaning test

[0135] 1. Ten oily sludge samples were separated from the same sludge sample. The first oily sludge sample was mixed with the switch-type microemulsion obtained in Example 4 at a ratio of 1:3. The mixture was heated to 70°C and stirred for 1 hour in a container. After standing for 10 minutes, quicklime was added to adjust the pH value to 8.0, and stirring was continued for 10 minutes.

[0136] 2. Three-phase separation of oil, water and solid is achieved by centrifugation, in which the oil layer is recovered, the oil content of the bottom sediment is measured after drying, the water phase is recovered, carbon dioxide is introduced, and the pH is adjusted to 6.0 for microemulsion regeneration.

[0137] 3. Mix the second oily sludge sample with the regenerated microemulsion at a ratio of 1:3, and repeat the above steps until all 10 oily sludge samples have been dried and the oil content is measured.

[0138] The measurement results are as follows:

[0139] 1 2.90 2 2.81 3 2.65 4 2.79 5 2.89 6 2.67 7 2.97 8 3.06 9 2.98 10 2.87

[0140] Analysis of the table above shows that after nine regenerations of the switch-type microemulsion, the cleaning effect on the oily sludge sample did not decrease, indicating that the switch-type microemulsion has a good cyclic cleaning effect.

[0141] Furthermore, it can significantly reduce costs while ensuring cleaning effectiveness; the generated calcium carbonate precipitate can dilute the bottom mud and reduce the oil content.

[0142] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this application can be achieved, and this is not limited herein.

[0143] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0144] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A switchable microemulsion, characterized in that, include: Lower fatty acids with no more than 10 carbon atoms in their carbon chains, anionic surfactants, basic co-surfactants, acidic co-surfactants, soluble inorganic carbonates, graphene-modified amines, and water; The alkaline co-surfactant is an alcohol amine and / or an ether amine, and the acidic co-surfactant is a polycarboxylic organic acid or its anhydride; the graphene-modified amine is one or more of graphene-modified polyether amine and graphene-modified polyol amine, and the ratio of the number of amino groups in the graphene-modified amine to the number of amino groups in the alkaline co-surfactant is (0~1):

10. The molar ratio of the lower fatty acid, basic co-surfactant, acidic co-surfactant, and inorganic carbonate is 1:(0.5~1.5):(0.5~1.5):(0.5~1.5); the mass ratio of the lower fatty acid to the anionic surfactant is 1:(0.1~1.0); water accounts for 50~95% of the total mass of the microemulsion; the pH value of the switch-type microemulsion is controlled at 5.6~6.

6.

2. A method for using a switchable microemulsion, characterized in that, include: Low-grade fatty acids with no more than 10 carbon atoms in their carbon chains, anionic surfactants, basic co-surfactants, acidic co-surfactants, soluble inorganic carbonates, and graphene-modified amines are dissolved in water to form a switch-type microemulsion. The alkaline co-surfactant is an alcohol amine and / or an ether amine, and the acidic co-surfactant is a polycarboxylic organic acid or its anhydride; the graphene-modified amine is one or more of graphene-modified polyether amine and graphene-modified polyol amine, and the ratio of the number of amino groups in the graphene-modified amine to the number of amino groups in the alkaline co-surfactant is (0~1):

10. The molar ratio of the lower fatty acids, basic co-surfactant, acidic co-surfactant, and inorganic carbonate is 1:(0.5~1.5):(0.5~1.5):(0.5~1.5); the mass ratio of the lower fatty acids to the anionic surfactant is 1:(0.1~1.0); water accounts for 50~95% of the total mass of the microemulsion; the pH value of the switch-type microemulsion is controlled at 5.6~6.

6. When it is necessary to convert the switch-type microemulsion into an aqueous dispersion, a soluble calcium compound is added to the switch-type microemulsion to convert it into an aqueous dispersion and generate calcium carbonate precipitate. When it is necessary to convert the aqueous dispersion into the switchable microemulsion, CO2 is added to the aqueous dispersion, and the aqueous dispersion is converted into a switchable microemulsion.

3. A method for treating oily sludge based on switchable microemulsions, characterized in that, include: Oily sludge is mixed with a switchable microemulsion to separate oil and sludge, resulting in an oil-containing microemulsion extract phase and forming bottom sludge precipitate. The switchable microemulsion includes lower fatty acids with no more than 10 carbon atoms in the carbon chain, anionic surfactants, basic co-surfactants, acidic co-surfactants, soluble inorganic carbonates, graphene-modified amines, and water. The alkaline co-surfactant is an alcohol amine and / or an ether amine, and the acidic co-surfactant is a polycarboxylic organic acid or its anhydride; the graphene-modified amine is one or more of graphene-modified polyether amine and graphene-modified polyol amine, and the ratio of the number of amino groups in the graphene-modified amine to the number of amino groups in the alkaline co-surfactant is (0~1):

10. The molar ratio of the lower fatty acids, basic co-surfactant, acidic co-surfactant, and inorganic carbonate is 1:(0.5~1.5):(0.5~1.5):(0.5~1.5); the mass ratio of the lower fatty acids to the anionic surfactant is 1:(0.1~1.0); water accounts for 50~95% of the total mass of the microemulsion; the pH value of the switch-type microemulsion is controlled at 5.6~6.

6. A soluble calcium compound is added to the microemulsion extraction phase, which transforms the microemulsion in the microemulsion extraction phase into an aqueous dispersion solution and generates calcium carbonate precipitate. At this time, the oil phase separates from the aqueous dispersion solution, resulting in an oil phase, an aqueous dispersion solution, and a mixed precipitate that are sequentially separated. The mixed precipitate includes sediment precipitate and calcium carbonate precipitate. The oil phase, aqueous dispersion, and mixed precipitate are separated, the oil phase is recovered, and CO2 is added to the aqueous dispersion to reconstitute the aqueous dispersion into a switchable microemulsion.

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