Liquid-liquid condensed phase system, preparation method and application thereof, and oil-containing oil sand cleaning method

Abstract

The invention relates to the technical field of oil sludge cleaning, and discloses a liquid-liquid condensed phase system, a preparation method and application thereof, and an oil-containing oil sand cleaning method, the liquid-liquid condensed phase system comprises an anionic cyclodextrin derivative, a gemini quaternary ammonium salt surfactant and water; wherein the charge ratio of the anionic cyclodextrin derivative to the gemini quaternary ammonium salt surfactant is (0.5-10): 1. The condensed-phase droplets in the obtained liquid-liquid phase separation system can be stably dispersed in water for more than 24 hours, and can quickly spread and permeate on the surface of an oil phase, so that the synergistic cleaning effect of the surfactant and the cyclodextrin derivative is exerted, and the oil washing efficiency is effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of oil sludge cleaning, and in particular to a liquid-liquid condensed phase system, a preparation method and application thereof, and an oil-containing oil sand cleaning method. Background Art

[0002] In recent years, the large amount of sludge generated during the extraction, transportation and refining of crude oil, as well as the oily soil after the decommissioning of oilfield wells and the relocation of refining sites have become environmental issues that have attracted much attention in the petroleum and petrochemical industry. The polar substances such as colloids and asphaltene in crude oil have strong adhesion to the surface of the siliceous substrate, making it difficult for crude oil to desorb from the solid surface of sand. How to strengthen the driving force of oil-solid separation and improve the efficiency of oil washing is the key to solving the technical problems of efficient cleaning of sludge and rapid repair of oily soil.

[0003] Surfactant molecules have both hydrophilic head groups and lipophilic alkyl chains, so they have oil-water amphiphilic characteristics. Their aqueous solutions can reduce the oil-water interfacial tension, thereby stripping the oil in the oil sands to the water phase for removal. Cyclodextrin derivatives are a kind of green agent that can carry dirty oil into the water phase by relying on their own hydrophobic cavities to solubilize pollutants. However, aqueous solutions of surfactants or cyclodextrin derivatives usually have insufficient affinity for crude oil, and the molecules are slowly adsorbed at the oil-water interface, making it difficult to penetrate into the oil phase. Therefore, there is a need to develop an oil washing system with better affinity for the oil phase.

[0004] The liquid-liquid phase separation phenomenon refers to the phenomenon that a homogeneous colloidal solution spontaneously separates into two immiscible phases (a dilute phase and a condensed phase), among which the condensed phase enriched with colloidal substances is called liquid-liquid phase separation. What is special about liquid-liquid phase separation is that it can spontaneously separate into phases, which makes it different from homogeneous solutions, precipitations and gels, and shows unique advantages in the separation and enrichment of substances. So far, liquid-liquid phase separation has been widely used in various industrial fields such as daily chemicals, sewage treatment, and protein purification. In theory, the mass concentration of colloidal substances contained in the condensed phase of liquid-liquid phase separation can be concentrated to more than 20%, which should significantly improve its affinity for the oil phase interface, thereby promoting the spreading and penetration of the agent on the surface of the oil phase, and at the same time, its adsorption and enrichment rate at the oil-water interface will also be greatly accelerated.

[0005] However, the industrial cleaning process of oily soil and sludge requires that the phase separation does not occur too quickly, and the condensed phase droplets need to have a certain stability before contacting the oil phase so that they can be dispersed in water, which makes most liquid-liquid phase separation systems unable to be applied in this field. Summary of the invention

[0006] The purpose of the present invention is to overcome the problems of poor oil phase affinity, poor stability and low oil washing efficiency of the oil washing agent in the prior art, and to provide a liquid-liquid condensed phase system and its preparation method and application, and an oil sand cleaning method. The liquid-liquid condensed phase system has a liquid-liquid phase separation structure, good stability, good spreading and permeability to the oil phase, and high oil washing efficiency.

[0007] In order to achieve the above object, the present invention provides a liquid-liquid coacervate phase system on one hand, wherein the coacervate phase system comprises an anionic cyclodextrin derivative, a gemini quaternary ammonium salt surfactant and water;

[0008] Wherein, the charge ratio of the anionic cyclodextrin derivative and the double-chain quaternary ammonium salt surfactant is (0.5-10):1.

[0009] The second aspect of the present invention provides a method for preparing the above-mentioned liquid-liquid condensed phase system.

[0010] A third aspect of the present invention provides the use of the liquid-liquid condensed phase system in industrial cleaning of oily soil and oily sludge.

[0011] A fourth aspect of the present invention provides a method for cleaning oil-containing oil sands, comprising: mixing the oil-containing oil sands and an oil washing agent under stirring conditions;

[0012] Wherein, the oil washing agent comprises the liquid-liquid condensed phase system described in the first aspect.

[0013] The present invention obtains a condensed phase system of liquid-liquid phase separation with a cyclodextrin derivative with good biocompatibility and a gemini quaternary ammonium salt surfactant. The condensed phase droplets in the obtained liquid-liquid phase separation system can be stably dispersed in water for more than 24 hours, meeting the residence time of the required cleaning agent for industrial cleaning processes such as oily soil and oil sludge produced in oil fields and refineries. After encountering the oil phase, the condensed phase droplets can be quickly spread and infiltrated on the oil phase surface, play the synergistic cleaning effect of the surfactant and the cyclodextrin derivative, and effectively improve the oil washing efficiency. Through the structure of the preferred anionic cyclodextrin derivative and the gemini quaternary ammonium salt surfactant, the dispersion stability of the liquid-liquid phase separation condensed phase droplets in water can be further improved, so that it can be applied to the industrial oil washing field. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a microscope picture of the liquid-liquid condensed phase system prepared in Example 1 of the present invention;

[0015] Figure 2 This is the contact condition of the droplets of the liquid-liquid condensed phase system obtained in Example 1 of the present invention on the oil phase surface. DETAILED DESCRIPTION

[0016] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0017] The first aspect of the present invention provides a liquid-liquid coacervate phase system, the liquid-liquid coacervate phase system comprising anionic cyclodextrin derivatives, gemini quaternary ammonium salt surfactants and water;

[0018] Wherein, the charge ratio of the anionic cyclodextrin derivative and the double-chain quaternary ammonium salt surfactant is (0.5-10):1.

[0019] In the prior art, anionic surfactants and cationic surfactants are usually not used for combination, because the combination of anionic and cationic surfactants is very likely to produce precipitation. The inventors of the present invention have found in their research that the combination of anionic cyclodextrin derivatives with a specific charge ratio and the double-chain quaternary ammonium salt surfactant has good dispersion stability in water, and the affinity of the condensed phase droplets to crude oil is strong, and they can quickly spread and penetrate on the oil phase surface, which can effectively promote the peeling of crude oil from the solid surface, and has high oil washing efficiency, and is particularly suitable for use as an efficient oil washing agent.

[0020] According to the present invention, the condensed phase system has a liquid-liquid phase separation structure. The liquid-liquid phase separation structure has a conventional definition in the art, and refers to a condensed phase enriched with colloidal substances whose internal microstructure is a random sponge-like structure. By observing under a microscope, small droplets of the condensed phase can be clearly seen, proving that a liquid-liquid phase separation has been formed.

[0021] In the present invention, the charge ratio of the anionic cyclodextrin derivative and the double-chain quaternary ammonium salt surfactant refers to the ratio of the molar amount of negative charges contained in the anionic cyclodextrin derivative to the molar amount of positive charges contained in the double-chain quaternary ammonium salt surfactant.

[0022] According to some preferred embodiments of the present invention, the charge ratio of the anionic cyclodextrin derivative and the gemini quaternary ammonium salt surfactant is (0.8-5):1, for example, it can be 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1, 2.2:1, 2.4:1, 2.6:1, 2.8:1, 3:1, 3.2:1, 3.4:1, 3.6:1, 3.8:1, 4:1, 4.2:1, 4.4:1, 4.6:1, 4.8:1, 5:1 and other typical but non-limiting charge ratios or ranges therebetween. Preferably, the charge ratio of the anionic cyclodextrin derivative and the gemini quaternary ammonium salt surfactant is (1.2-4):1. In the above preferred case, the surface of the liquid-liquid phase separation droplets has a certain negative charge, and the electrostatic repulsion between the droplets delays the coalescence process between the droplets, which is further beneficial to improving the dispersion stability of the liquid-liquid phase separation droplets in water.

[0023] In the present invention, the anionic cyclodextrin derivative refers to a product derived from a cyclodextrin in which the H atom on at least one hydroxyl group is replaced by an anionic hydrophilic group or an alkylene group with an anionic hydrophilic group at the end. Various anionic cyclodextrin derivatives known in the art can be applied to the present invention, for example, it can be at least one of the sulfonate type, sulfate type, phosphate type and carboxylate type cyclodextrin derivatives.

[0024] Preferably, the anionic cyclodextrin derivative has a structure as shown in formula (1),

[0025]

[0026] Wherein, m is selected from any integer from 1 to 10, and n is selected from any integer from 0 to 10;

[0027] The R1 group contains any one of -SO3M, -COOM, -PO3M2 and -PO3HM, and optionally a C1-C4 alkylene group, wherein M is an alkali metal, for example, any one of Li, Na and K, preferably Na or K.

[0028] According to the present invention, the R1 group can be selected from any one of -SO3M, -COOM, -PO3M2 and -PO3HM, or can be a combination of a C1-C4 alkylene group and any one of -SO3M, -COOM, -PO3M2 and -PO3HM.

[0029] In the present invention, the C1-C4 alkylene group may be a linear or branched alkylene group, preferably a linear alkylene group, such as a methylene group, an ethylene group, a propylene group or a butylene group.

[0030] Preferably, m is selected from any integer of 1-8, and n is selected from any integer of 0-7.

[0031] According to some preferred embodiments of the present invention, R1 is any one of the groups having structures shown in formula (1-1) to formula (1-5),

[0032]

[0033] Wherein, M is an alkali metal, preferably Na or K.

[0034] The use of anionic cyclodextrin derivatives with the above-mentioned preferred structure, which contain several hydroxyl groups and anionic head groups in their molecules, is beneficial to regulating the interaction forces between them and cationic quaternary ammonium surfactants, such as hydrogen bond interactions and electrostatic interactions, and is beneficial to further improving the dispersion stability of liquid-liquid phase separation condensed phase droplets in water.

[0035] In the present invention, the "gemini quaternary ammonium salt surfactant" has the conventional definition in the art, and may also be referred to as a cationic quaternary ammonium salt gemini surfactant.

[0036] According to some preferred embodiments of the present invention, the gemini quaternary ammonium salt surfactant has a structure shown in formula (2),

[0037]

[0038] wherein each R2 is independently selected from a saturated or unsaturated hydrocarbon group of C8-22; R3 contains at least one of an alkylene group, a hydroxyl group and an amide group; and each R4 is independently selected from a methyl group or an ethyl group;

[0039] X is halogen, preferably Cl or Br.

[0040] In the present invention, "C8-22 saturated or unsaturated hydrocarbon group" means a saturated hydrocarbon group or an unsaturated hydrocarbon group having a total carbon atom count of 8-22. The saturated hydrocarbon group of C8-22 may be, for example, a straight chain alkyl group or a branched chain alkyl group having a total carbon atom count of 8, 9, 10, 11, 12, 13, 14, 15, 16, 18, 20, or 22, such as n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-hexadecyl, etc. The unsaturated hydrocarbon group of C8-22 may be, for example, a carbon chain or an aromatic ring containing an unsaturated bond.

[0041] According to the present invention, in formula (2), R3 is a linking group between two amphiphilic moieties, and the R3 group contains at least one of an alkylene group, a hydroxyl group and an amide group.

[0042] According to some preferred embodiments of the present invention, R3 is a group having a structure shown in any one of formula (2-1) to formula (2-4),

[0043]

[0044] In formula (2-1), s is an integer selected from 0-10, preferably an integer from 0-4.

[0045] According to some preferred embodiments of the present invention, the anionic cyclodextrin derivative has a structure as shown in formula (1), wherein m is selected from any integer of 1-8, n is selected from any integer of 0-7, and R1 is any one of the groups having structures shown in formulas (1-1) to (1-5); the gemini quaternary ammonium salt surfactant has a structure as shown in formula (2), wherein R2 is selected from a saturated or unsaturated hydrocarbon group of C8-22, X is Cl or Br, and R3 is a group having a structure as shown in any one of formulas (2-1) to (2-4).

[0046] The combination of a gemini quaternary ammonium salt surfactant having the above-mentioned preferred structure and an anionic cyclodextrin derivative is beneficial for adjusting the interaction force between the two and the cationic quaternary ammonium salt surfactant by means of several quaternary ammonium salt head groups, anionic head groups, hydroxyl groups and other groups contained in the two, which is beneficial for further improving the dispersion stability of liquid-liquid phase separation condensed phase droplets in water and improving oil washing efficiency.

[0047] The present invention has a wide selection range for the dosage ratio of surfactant to water in the liquid-liquid condensed phase system. The anionic cyclodextrin derivative and the gemini quaternary ammonium salt surfactant are combined using the above-mentioned charge ratio to form a liquid-liquid phase separation condensed phase system, and the condensed phase droplets in the obtained liquid-liquid phase separation system can be stably dispersed in water.

[0048] According to some preferred embodiments of the present invention, based on the total amount of the condensed phase system, the molar concentration of the anionic cyclodextrin derivative is not less than 0.05mmol / L, preferably 0.1-2mmol / L. For example, it can be 0.1mmol / L, 0.2mmol / L, 0.3mmol / L, 0.4mmol / L, 0.5mmol / L, 0.6mmol / L, 0.7mmol / L, 0.8mmol / L, 0.9mmol / L, 1mmol / L, 1.1mmol / L, 1.2.mmol / L, 1.3mmol / L, 1.4mmol / L, 1.5mmol / L, 1.6mmol / L, 1.7mmol / L, 1.8mmol / L, 1.9mmol / L, 2mmol / L and other typical but non-limiting proportions. Within the above preferred range, the concentration of the colloidal substance and the strength of the intermolecular interaction force are both conducive to the stability of the liquid-liquid phase separation.

[0049] Preferably, based on the total amount of the condensed phase system, the total molar concentration of the anionic cyclodextrin derivative and the gemini quaternary ammonium salt surfactant is not less than 0.1mmol / L, preferably 0.3-10mmol / L, for example, it can be 0.3mmol / L, 0.4mmol / L, 0.5mmol / L, 0.6mmol / L, 0.7mmol / L, 0.8mmol / L, 0.9mmol / L, 1mmol / L, 2mmol / L, 3mmol / L, 4mmol / L, 5mmol / L, 6mmol / L, 7mmol / L, 8mmol / L, 9mmol / L, 10mmol / L and other typical but non-limiting concentration values ​​or the range therebetween.

[0050] The second aspect of the present invention provides a method for preparing the above-mentioned coacervated phase system, comprising: separately preparing an aqueous solution A of anionic cyclodextrin derivatives and an aqueous solution A of gemini quaternary ammonium salt surfactants and then mixing aqueous solution A and aqueous solution B.

[0051] According to the present invention, a liquid-liquid coacervate phase system with liquid-liquid phase separation can be obtained by simply mixing anionic cyclodextrin derivatives and gemini quaternary ammonium salt surfactants. The preparation method is simple and efficient.

[0052] According to the present invention, the specific selection of the anionic cyclodextrin derivative and the gemini quaternary ammonium salt surfactant is the same as the definition range of the first aspect, and will not be repeated here. The amount of the aqueous solution A and the aqueous solution B is such that the charge ratio of the anionic cyclodextrin derivative and the gemini quaternary ammonium salt surfactant is (0.5-10):1.

[0053] The present invention has no particular limitation on the concentrations of the aqueous solution A and the aqueous solution B. Preferably, the concentration of the mixed solution can be selected as long as it meets the above-mentioned preferred range. Those skilled in the art can make the selection according to actual conditions.

[0054] The present invention has no particular requirement for the mixing order of the aqueous solution A and the aqueous solution B. Preferably, the mixing is performed under stirring conditions with a stirring rate of 20-1000 rpm, preferably 100-300 rpm.

[0055] The present invention has no special requirements for the temperature and pressure of the mixing, and the mixing can be carried out under normal temperature and pressure.

[0056] The third aspect of the present invention provides the use of the above-mentioned condensed phase system in industrial cleaning of oily soil and oily sludge.

[0057] Conventional liquid-liquid phase separation systems in the prior art can be divided into polymer systems, polymer-surfactant complex systems, and surfactant-organic small molecule complex systems. However, polymers are easily adsorbed and retained on the surface of sand and soil, causing secondary pollution. At the same time, the industrial cleaning process of oily soil and sludge requires that the phase separation rate cannot be too fast, and the condensed phase droplets need to have a certain stability before contacting the oil phase so that they can be dispersed in water. This makes most liquid-liquid phase separation systems unable to be applied to the industrial cleaning field of oily soil and sludge.

[0058] The small droplets of the coagulated phase in the liquid-liquid coagulated phase system provided by the present invention can be stably dispersed in water for more than 24 hours, meeting the residence time of the cleaning agent required by industrial cleaning processes such as oily soil and sludge produced in oil fields and refineries. After encountering the oil phase, the coagulated phase droplets can quickly spread and penetrate on the surface of the oil phase, exert the synergistic cleaning effect of the anionic cyclodextrin derivative and the gemini quaternary ammonium salt surfactant, effectively improve the oil washing efficiency, and have good application prospects.

[0059] A fourth aspect of the present invention provides a method for cleaning oil-containing oil sands, comprising: mixing the oil-containing oil sands and an oil washing agent under stirring conditions;

[0060] Wherein, the oil washing agent is the condensed phase system described in the first aspect.

[0061] According to some preferred embodiments of the present invention, the liquid-solid mass ratio of the oil washing agent to the oil-containing oil sand is (1-10):1, for example, it can be 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1 and other typical but non-limiting ratios or ranges therebetween. Preferably, the liquid-solid mass ratio of the oil washing agent to the oil-containing oil sand is (2-5):1. In the above preferred case, it is conducive to the full interaction between the oil washing agent and the oil sand, thereby improving the oil washing efficiency.

[0062] In the present invention, the oil-containing oil sand can be oil-containing sludge produced during the exploitation, pipeline transportation and refining of crude oil, or oil-contaminated soil after the decommissioning well site of an oil field and the relocation of a refining site. The content of crude oil pollutants in the oil-containing oil sand is not less than 5wt%, preferably 5-25wt%. For the oil-containing oil sand of the above composition, the oil washing agent provided by the present invention has a more excellent cleaning effect.

[0063] The present invention has no particular limitation on the conditions for mixing the oil-containing oil sands and the oil washing agent, and the conventional operating conditions in the art can be adopted. Preferably, the mixing temperature is 40-65°C, preferably 50-60°C, the stirring rate is 100-200rpm, preferably 120-150rpm, and the mixing time is 1-12h, preferably 2-4h.

[0064] The present invention will be described in detail below through examples.

[0065] In the following examples, unless otherwise specified, all reagents used are commercially available chemical reagents.

[0066] Example 1

[0067] Preparation based on liquid-liquid phase separation of sulfobutyl-β-cyclodextrin and gemini quaternary ammonium salt 12-6-12. The structural formulas of sulfobutyl-β-cyclodextrin (purchased from Accela, purity 98%, item number SY003635) and 12-6-12 (prepared according to the method described in Langmuir 1991, 7, 1072-1075) are shown in the following formula a1 and formula b1 respectively:

[0068]

[0069] Among them, the m value is 2 and the n value is 5.

[0070]

[0071] Weigh 0.435g of sulfobutyl-β-cyclodextrin and prepare it into 100mL of aqueous solution (molar concentration 3mM); weigh 0.067g of 12-6-12 Gemini surfactant and prepare it into 100mL of aqueous solution (molar concentration 1mM). Then, gradually add the 12-6-12 aqueous solution into the sulfobutyl-β-cyclodextrin aqueous solution under stirring. The two prepared aqueous solutions are stirred and mixed at room temperature at a stirring speed of 300rpm to prepare a liquid-liquid condensed phase system. Observe under a microscope at a magnification of 40 times, as shown in FIG. Figure 1 As shown, small droplets of the condensed phase can be clearly seen, proving that liquid-liquid phase separation has occurred.

[0072] In the system, the molar concentration of sulfobutyl-β-cyclodextrin is 1.5 mM, the molar concentration of 12-6-12 gemini surfactant is 0.5 mM, and the mixed charge ratio of sulfobutyl-β-cyclodextrin and 12-6-12 is 3:1.

[0073] Example 2

[0074] Preparation based on liquid-liquid phase separation of carboxymethyl-β-cyclodextrin and gemini quaternary ammonium salt 12-3-12. The structural formulas of carboxymethyl-β-cyclodextrin (purchased from Inokai, purity 99%, item number A62744) and 12-3-12 (prepared according to the method described in Langmuir 1991, 7, 1072-1075) are shown in the following formula a2 and formula b2 respectively:

[0075]

[0076] Among them, the m value is 7 and the n value is 0.

[0077]

[0078] Weigh 0.0308 g of carboxymethyl-β-cyclodextrin and prepare it into 100 mL of aqueous solution (molar concentration 0.2 mM); weigh 0.0366 g of 12-3-12 gemini quaternary ammonium salt surfactant and prepare it into 100 mL of aqueous solution (molar concentration 0.584 mM). Then, the carboxymethyl-β-cyclodextrin aqueous solution is gradually added to the 12-3-12 aqueous solution under stirring conditions, and the above two prepared aqueous solutions are mixed while stirring at room temperature at a stirring speed of 100 rpm to prepare a liquid-liquid condensed phase system.

[0079] In the system, the molar concentration of carboxymethyl-β-cyclodextrin is 0.1 mM, the molar concentration of 12-3-12 gemini quaternary ammonium salt surfactant is 0.292 mM, and the mixed charge ratio of carboxymethyl-β-cyclodextrin and 12-6-12 is 1.2:1.

[0080] Example 3

[0081] Preparation based on liquid-liquid phase separation of sulfobutyl-β-cyclodextrin and gemini quaternary ammonium salt Malic-2C12. The structural formula of sulfobutyl-β-cyclodextrin (purchased from Accela, purity 98%, item number SY003635) is shown in formula a1, and the structural formula of gemini quaternary ammonium salt Malic-2C12 (prepared according to Example 1 of invention patent CN111072511B) is shown in b3:

[0082]

[0083] Weigh 0.58 g of sulfobutyl-β-cyclodextrin and prepare it into 100 mL of aqueous solution (molar concentration 4 mM); weigh 0.077 g of Malic-2C12 gemini quaternary ammonium salt surfactant and prepare it into 100 mL of aqueous solution (molar concentration 1 mM). Then, the Malic-2C12 aqueous solution is gradually added to the sulfobutyl-β-cyclodextrin aqueous solution under stirring conditions, and the above two prepared aqueous solutions are stirred and mixed at room temperature at a stirring speed of 250 rpm to prepare a liquid-liquid condensed phase system.

[0084] In the system, the molar concentration of sulfobutyl-β-cyclodextrin is 2 mM, the molar concentration of Malic-2C12 gemini surfactant is 0.5 mM, and the mixed charge ratio of sulfobutyl-β-cyclodextrin and Malic-2C12 is 4:1.

[0085] Example 4

[0086] The method of Example 1 is followed, except that 0.435 g of sulfobutyl-β-cyclodextrin is weighed and prepared into 100 mL of aqueous solution (molar concentration 3 mM); 0.201 g of 12-6-12 gemini surfactant is weighed and prepared into 100 mL of aqueous solution (molar concentration 3 mM). After mixing, a liquid-liquid coacervate phase system is obtained.

[0087] In the system, the molar concentration of sulfobutyl-β-cyclodextrin is 1.5 mM, the molar concentration of 12-6-12 gemini surfactant is 1.5 mM, and the mixed charge ratio of sulfobutyl-β-cyclodextrin and 12-6-12 is 1:1.

[0088] Example 5

[0089] The method of Example 1 is followed, except that the Gemini quaternary ammonium salt surfactant 12-6-12 is replaced by 12-3-12, and its linking group is changed from —(CH2)6— to —(CH2)3—. The structure of 12-3-12 is shown in formula b4:

[0090]

[0091] Accordingly, 0.063 g of 12-3-12 gemini surfactant was weighed and prepared into 100 mL of aqueous solution (molar concentration 1 mM), and a liquid-liquid condensed phase system was obtained after mixing.

[0092] In the system, the molar concentration of sulfobutyl-β-cyclodextrin is 1.5 mM, the molar concentration of 12-3-12 gemini surfactant is 0.5 mM, and the mixed charge ratio of sulfobutyl-β-cyclodextrin and 12-3-12 is 3:1.

[0093] Example 6

[0094] According to the method of Example 1, the difference is that

[0095] Weigh 0.0232 g of sulfobutyl-β-cyclodextrin and prepare it into 100 mL of aqueous solution (molar concentration 0.16 mM); weigh 0.0355 g of 12-6-12 gemini surfactant and prepare it into 1000 mL of aqueous solution (molar concentration 0.053 mM). Weigh 100 mL of 12-6-12 aqueous solution and mix it with 100 mL of sulfobutyl-β-cyclodextrin aqueous solution to obtain a liquid-liquid coacervate phase system.

[0096] In the system, the molar concentration of sulfobutyl-β-cyclodextrin is 0.08 mM, the molar concentration of 12-6-12 gemini surfactant is 0.027 mM, and the mixed charge ratio of sulfobutyl-β-cyclodextrin and 12-6-12 is 3:1.

[0097] Comparative Example 1

[0098] Preparation of the composite system of sulfobutyl-β-cyclodextrin and single-chain quaternary ammonium salt dodecyltrimethylammonium bromide (DTAB).

[0099] Weigh 0.435 g of sulfobutyl-β-cyclodextrin and prepare it into 100 mL of aqueous solution (molar concentration 3 mM); weigh 0.062 g of single-chain quaternary ammonium salt surfactant DTAB and prepare it into 100 mL of aqueous solution (molar concentration 2 mM). Then, the DTAB aqueous solution is gradually added to the sulfobutyl-β-cyclodextrin aqueous solution under stirring conditions, and the above two prepared aqueous solutions are mixed while stirring at a stirring speed of 300 rpm at room temperature to prepare a composite system.

[0100] In the system, the molar concentration of sulfobutyl-β-cyclodextrin is 1.5 mM, the molar concentration of DTAB surfactant is 1 mM, and the mixed charge ratio of sulfobutyl-β-cyclodextrin and DTAB is 3:1.

[0101] The composite system is clear and transparent, and no liquid-liquid phase separation occurs.

[0102] Comparative Example 2

[0103] 0.218 g of sulfobutyl-β-cyclodextrin was weighed and prepared into 100 mL of aqueous solution (molar concentration 1.5 mM). The obtained aqueous solution was clear and transparent without liquid-liquid phase separation.

[0104] Comparative Example 3

[0105] 0.034 g of 12-6-12 gemini surfactant was weighed and prepared into 100 mL of aqueous solution (molar concentration 0.5 mM). The obtained aqueous solution was clear and transparent without forming liquid-liquid phase separation.

[0106] Test Case

[0107] (1) Determination of the wetting ability of the liquid-liquid phase separation system on the oil-containing surface:

[0108] The oil phase used is crude oil separated from oily soil of Shengli HK oilfield (crude oil pollutant content 16 wt%) and oil sludge of YS refinery (crude oil pollutant content 20 wt%).

[0109] First, the oil phase in the oil-containing oil sands is uniformly coated on the surface of a clean glass slide at high temperature and allowed to cool naturally. Then, the contact angle of the droplets of the liquid-liquid condensed phase system prepared in the above embodiments and comparative examples on the surface of the glass slide is measured by the sessile drop method using a KRUSSDSA100 contact angle meter. The contact angle experiment temperature is controlled at 25°C. The timing starts when the droplets reach the oily interface. After balancing for 3 minutes, the contact angle is obtained by photographing and fitting. The measurement results are shown in Table 1. Among them, the contact conditions of the droplets of the liquid-liquid condensed phase system prepared in Example 1 on the surface of the glass slide are shown in Table 1. Figure 2 As shown, it can be seen that the liquid-liquid phase separation system has good spreading performance on the oil phase surface and a small contact angle.

[0110] Table 1

[0111]

[0112] As shown in Table 1, the liquid-liquid phase separation obtained in the embodiment of the present invention has lower contact angle (all lower than 20 degree) on oily surface, proving that the liquid-liquid phase separation system prepared has the ability of rapid spreading and infiltration on the oily surface of oil-bearing oil-sand.Preferably, the liquid-liquid phase separation system prepared by embodiment 1-3 is all lower than 15 degree in the contact angle on oily surface, and penetration ability is better.By contrast, after gemini quaternary ammonium salt surfactant is changed into single-chain quaternary ammonium salt surfactant, the contact angle is higher than 40 degree, and the wetting ability of system on oily surface decreases obviously.And when sulfobutyl cyclodextrin or gemini quaternary ammonium salt surfactant single component exists, the contact angle of droplet on oily surface is all higher than 60 degree, and the wetting ability on oil phase surface is weaker.

[0113] (2) Determination of water dispersion stability of liquid-liquid phase separation droplets:

[0114] 100 mL of the liquid-liquid condensed phase system prepared in the above examples was taken respectively, transferred to a transparent stoppered graduated glass test tube, allowed to stand, and the time required for the liquid-liquid phase separation system to begin to have an obvious phase separation boundary was observed and recorded.

[0115] At the same time, the Zeta potential of the newly prepared liquid-liquid phase separation system solution at 25°C was tested using a Malven Zetasizer Nano-ZS instrument. The results are shown in Table 2.

[0116] Table 2

[0117] serial number t / h Zeta potential / mV Example 1 28.0 -6.55 Example 2 26.5 -4.83 Example 3 25.5 -3.75 Example 4 27.0 -2.51 Example 5 24.5 -6.40 Example 6 38.5 -3.33

[0118] The results in Table 2 show that the liquid-liquid phase separation droplets can be stably dispersed in water for more than 24 hours, which fully meets the requirements of the industrial cleaning process for oily soil and sludge. The reason for the good dispersion stability of the liquid-liquid phase separation system is that the surface of the condensed phase droplets is negatively charged, and their Zeta potentials are all negative, and the absolute values ​​are all higher than 2.50 mV, which proves that there is electrostatic repulsion between the droplets.

[0119] (3) Evaluation of oil washing ability:

[0120] This evaluation test uses Shengli HK oilfield oily soil (crude oil pollutant content 16wt%) and YS refinery sludge (crude oil pollutant content 20wt%) as oil washing targets. Take 10g of sludge in a 100mL conical flask, add the aqueous solution oil washing system prepared in the above embodiment and comparative example respectively (the amount added is shown in Table 3), seal it and place it in a Jinyi SHZ-88 water bath constant temperature oscillator to heat to 40°C, and shake it at a constant rate of 30rpm for 4 hours. After cooling to room temperature, let it stand and settle to separate, separate the solution and the washed crude oil from the solid phase, dry the separated solid at 100°C to constant weight, and weigh its weight m.

[0121] The cleaning efficiency of the washing oil system is calculated by the following formula, and the calculation results are shown in Table 3:

[0122] Cleaning efficiency = (mass of unwashed oil-bearing sands - m) / mass of crude oil pollutants in unwashed oil-bearing sands × 100%.

[0123] Table 3 Cleaning efficiency of different washing oil systems

[0124]

[0125]

[0126] The result of table 3 shows, the liquid-liquid phase separation oil washing system that the embodiment of the present invention makes can play a good cleaning effect to oil field and refinery oil sludge, and the cleaning efficiency of dirty oil can reach more than 82.4% and 83.2% respectively, and can reach more than 85% and 90% respectively under the preferred situation.By contrast, the gemini quaternary ammonium salt surfactant is changed into single-chain quaternary ammonium salt surfactant, and the composite system formed with cyclodextrin derivative can't form liquid-liquid phase separation, and the highest oil washing efficiency to oil field and refinery oil sludge is respectively 78.6% and 80.2%.In addition, the oil washing efficiency when cyclodextrin derivative or gemini quaternary ammonium salt surfactant exists separately is lower than 62%.Thus prove, the liquid-liquid phase separation system provided by the present invention can be used as efficient green oil washing agent, and has good application prospect in the oil sludge efficient cleaning and oily soil rapid repair field produced in oil field and refinery.

[0127] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A liquid-liquid condensed phase system, characterized in that: The liquid-liquid coacervate phase system comprises anionic cyclodextrin derivatives, gemini quaternary ammonium salt surfactants and water; Wherein, the charge ratio of the anionic cyclodextrin derivative and the gemini quaternary ammonium salt surfactant is (0.5-10):

1.

2. The liquid-liquid condensed phase system according to claim 1, wherein: The liquid-liquid condensed phase system has a liquid-liquid phase separation structure.

3. The liquid-liquid condensed phase system according to claim 1 or 2, wherein: The charge ratio of the anionic cyclodextrin derivative and the gemini quaternary ammonium salt surfactant is (0.8-5):1, preferably (1.2-4):

1.

4. The liquid-liquid condensed phase system according to any one of claims 1 to 3, wherein: The anionic cyclodextrin derivative is at least one of sulfonate type, sulfate type, phosphate type and carboxylate type cyclodextrin derivatives.

5. The liquid-liquid condensed phase system according to claim 4, wherein: The anionic cyclodextrin derivative has a structure shown in formula (1), Wherein, m is selected from any integer from 1 to 10, and n is selected from any integer from 0 to 10; The R1 group contains any one of -SO3M, -COOM, -PO3M2 and -PO3HM, and an optional C1-C5 alkylene group; wherein M is an alkali metal, preferably Na or K; Preferably, R1 is any one of the groups of structures shown in formula (1-1) to formula (1-5), Wherein, M is an alkali metal, preferably Na or K.

6. The liquid-liquid condensed phase system according to any one of claims 1 to 5, wherein: The gemini quaternary ammonium salt surfactant has a structure shown in formula (2), wherein each R2 is independently selected from a saturated or unsaturated hydrocarbon group of C8-22; R3 contains at least one of an alkylene group, a hydroxyl group and an amide group; and each R4 is independently selected from a methyl group or an ethyl group; X is halogen, preferably Cl or Br.

7. The liquid-liquid condensed phase system according to claim 6, wherein: R3 is a group having a structure represented by any one of formula (2-1) to formula (2-4), In formula (2-1), s is an integer selected from 0-10, preferably an integer from 0-4.

8. The liquid-liquid condensed phase system according to any one of claims 1 to 7, wherein: Based on the total amount of the liquid-liquid condensed phase system, the molar concentration of the anionic cyclodextrin derivative is not less than 0.05 mmol / L, preferably 0.1-2 mmol / L; Preferably, based on the total amount of the liquid-liquid coacervate phase system, the total molar concentration of the anionic cyclodextrin derivative and the gemini quaternary ammonium salt surfactant is not less than 0.1 mmol / L, preferably 0.3-10 mmol / L.

9. The method for preparing the liquid-liquid condensed phase system according to any one of claims 1 to 8, comprising: Separately preparing an aqueous solution A of anionic cyclodextrin derivatives and an aqueous solution B of gemini quaternary ammonium salt surfactants, and then mixing the aqueous solution A and the aqueous solution B; Preferably, the mixing is carried out under stirring conditions, with a stirring rate of 20-1000 rpm, preferably 100-300 rpm.

10. Use of the liquid-liquid condensed phase system according to any one of claims 1 to 8 in industrial cleaning of oily soil and oil sludge.

11. A method for cleaning oil-containing oil sands, comprising: Mixing the oil-bearing oil sand and the oil washing agent under stirring conditions; Wherein, the oil washing agent comprises the liquid-liquid condensed phase system as described in any one of claims 1 to 8; Preferably, the liquid-to-solid mass ratio of the oil washing agent to the oil-containing oil sand is (1-10):1, preferably (2-5):1; Preferably, the content of crude oil pollutants in the oil-bearing oil sand is not less than 5wt%; Preferably, the mixing temperature is 40-65° C., the stirring rate is 100-200 rpm, and the mixing time is 1-12 h.

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