Core-shell structured anionic nano microemulsion system, and preparation and application thereof

Abstract

The invention discloses a core-shell structured anionic nano microemulsion system, and preparation and application thereof. The system comprises an anionic Gemini surfactant, an oil phase material, a solubilizer and water; wherein the microemulsion has a core-shell structure, with the outer shell being an anionic Gemini surfactant, and the inner core being an oil phase material. The anionic Gemini surfactant is N,N,N′,N′-dodecyl tetrasubstituted diphenyl ether sulfonate having the structural formula: ##STR00001## The anionic nano-microemulsion system of the present invention is homogeneous and transparent, has a spherical core-shell structure, has a nanometer size (3 to 40 nm) as droplets, has a narrow particle size distribution, is not easy to agglomerate, has good stability, and has an ultra-low interfacial tension and a capability of reducing viscosity of crude oil.

Claims

1. A core-shell structured anionic nano microemulsion system, wherein the system comprises: an anionic Gemini surfactant, an oil phase material, a solubilizer and water; wherein the microemulsion has a core-shell structure, with the outer shell being the anionic Gemini surfactant, and the inner core being the oil phase material; and the anionic Gemini surfactant is N,N,N′,N′-dodecyl tetrasubstituted diphenyl ether sulfonate having the structural formula: ##STR00005##

2. The anionic nano microemulsion system according to claim 1, wherein the microemulsion has a droplet size ranging from 5 to 300 nm.

3. The anionic nano microemulsion system according to claim 1, wherein the microemulsion has an effective concentration of of 0.05 to 0.5%, wherein the effective concentration is the total concentration of the anionic Gemini surfactant, the oil phase material and the solubilizer.

4. The anionic nano microemulsion system according to claim 3, wherein the anionic Gemini surfactant accounts for 5 to 77% by mass, the oil phase material accounts for 5 to 46% by mass, and the solubilizer accounts for 5 to 31% by mass.

5. The anionic nano microemulsion system according to claim 1, wherein the oil phase material is selected from an aromatic hydrocarbon compound, a heterocyclic compound, and a terpene compound, or a combination thereof.

6. The anionic nano microemulsion system according to claim 5, wherein the oil phase material is selected from xylene, pyrrolidone, menthol, alpha-pinene, beta-myrcene, limonene, or a combination thereof.

7. The anionic nano microemulsion system according to claim 1, wherein the solubilizer is selected from one or more small molecule alcohol compounds.

8. The anionic nano microemulsion system according to claim 7, wherein the solubilizer is selected from ethanol, propanol, isopropanol, ethylene glycol, butanol, pentanol, or a combination thereof.

9. The anionic nano microemulsion system according to claim 1, wherein the anionic nano microemulsion system further comprises an inorganic salt.

10. The anionic nano microemulsion system according to claim 9, wherein the inorganic salt has a mass content of 0 to 15%, excluding 0.

11. A preparation method for the anionic nano microemulsion system according to claim 1, wherein the method comprises: S1, mixing an anionic Gemini surfactant, an oil phase material, a solubilizer and water well, to obtain a homogeneous mixed solution; or mixing an anionic Gemini surfactant, an oil phase material, and a solubilizer well, to obtain a homogeneous mixed solution; and S2, diluting the homogeneous mixed solution using water or inorganic brine to a low concentration condition, to obtain the core-shell structured anionic nano microemulsion system.

12. The preparation method according to claim 11, wherein the homogeneous mixed solution from S1 comprises by mass: 5 to 50% of the anionic Gemini surfactant, 5 to 30% of the oil phase material, 5 to 20% of the solubilizer, and water to balance.

13. The preparation method according to claim 11, wherein the low concentration condition is that the effective concentration of the microemulsion is 0.05 to 0.5%.

14. The preparation method according to claim 11, wherein the oil phase material is selected from an aromatic hydrocarbon compound, a heterocyclic compound, a terpene compound, or a combination thereof.

15. The preparation method according to claim 11, wherein the oil phase material is selected from xylene, pyrrolidone, menthol, alpha-pinene, beta-myrcene, limonene, or a combination thereof.

16. The preparation method according to claim 11, wherein the solubilizer is selected from ethanol, propanol, isopropanol, ethylene glycol, butanol, pentanol, or a combination thereof.

17. The preparation method according to claim 11, wherein in S2, the inorganic salt brine is used for diluting, and the obtained anionic nano microemulsion system has an inorganic salt mass content of 0 to 15%, excluding 0.

18. The preparation method according to claim 11, wherein the microemulsion in the anionic nano microemulsion system has a droplets size ranged from 5 to 300 nm.

19. The preparation method according to claim 11, wherein the mixing and diluting are carried out under an agitation at 10 to 400 rpm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic view of the structure of a microemulsion of the present invention.

(2) FIG. 2 is an infrared spectrum of N,N,N′,N′-dodecyl tetrasubstituted diphenyl ether sulfonate.

(3) FIG. 3 is a nuclear magnetic hydrogen spectrum of N,N,N′,N′-dodecyl tetrasubstituted diphenyl ether sulfonate.

(4) FIG. 4 is a graph of surface tension versus concentration (25° C.) of N,N,N′,N′-dodecyl tetrasubstituted diphenyl ether sulfonate.

(5) FIG. 5 is a graph showing the average particle size distribution of an anionic nano microemulsion prepared in Example 1 over time.

(6) FIG. 6 is a graph showing the average particle size distribution of an anionic nano microemulsion prepared in Example 2 over time.

(7) FIG. 7 is a graph showing the average particle size distribution of an anionic nano microemulsion prepared in Example 3 over time.

(8) FIG. 8 is a TEM image of an anionic nano microemulsion prepared in Example 4 at a mass concentration of 0.1%.

(9) FIG. 9 is a TEM image of an anionic nano microemulsion prepared in Example 4 at a mass concentration of 0.3%.

(10) FIG. 10 is a graph showing the initial particle size and its distribution of an anionic nano microemulsion prepared in Example 4 at a mass concentration of 0.1%.

(11) FIG. 11 is a graph showing the initial particle size and its distribution of an anionic nano microemulsion prepared in Example 4 at a mass concentration of 0.3%.

(12) FIG. 12 is a graph showing the average particle size distribution of an anionic nano microemulsion prepared in Example 4 over time.

(13) FIG. 13 is a graph showing the effect of an anionic nano microemulsion prepared in Example 4 on the viscosity reduction of a certain crude oil from Xinjiang.

DETAILED DESCRIPTION OF THE INVENTION

(14) In order to more clearly illustrate that present invention, the present invention will be further described in connection with preferred examples. It will be understood by those skilled in the art that the following detailed description is illustrative but not limiting, and should not be used to limit the scope of the invention.

Preparation of anionic Gemini surfactant of N,N,N′,N′-dodecyl tetrasubstituted diphenyl ether sulfonate

(15) ##STR00004##

(1) Synthesis of N,N,N′,N′-dodecyl tetrasubstituted diphenyl ether

(16) Into a three-necked flask placed in a constant temperature water bath and equipped with a stirrer, 25.00 g (124.85 mmol) of 4,4′-diamino diphenyl ether, 10.46 g (41.95 mmol) of bromodecane and 5.80 g of K.sub.2CO.sub.3 (20 wt %) as deacid reagent were added sequentially. With maintaining the pH of the system=7-10, 150 mL of DMF as solvent was added under the protection of nitrogen. With stirring, the temperature was raised to 60° C., and after 24 hours of reaction, the reaction was completed (the end point of the reaction is monitored by TLC, and the developing agent is V (petroleum ether):V (ethyl acetate)=10:1). Water was added for liquid separation. The aqueous phase was extracted three times with ethyl acetate and the organic phase was washed with water. The resultant was concentrated to dryness, purified through column and dried to give 80 g (91.58 mmol) of N,N,N′,N′-dodecyl tetrasubstituted diphenyl ether as a yellow oily intermediate.

(2) Synthesis of N,N,N′,N′-dodecyl tetrasubstituted diphenyl ether sulfonate

(17) With the reaction device same as that in (1), into a three-necked flask, 2.00 g (9.158 mmol) of N,N,N′,N′-dodecyl tetrasubstituted diphenyl ether and 50 mL of acetic acid as solvent were added sequentially, and 10 mL of concentrated sulfuric acid was added dropwise with ice bath and stirring. After the dropwise addition was completed, the temperature was raised to room temperature, and the reaction was carried out for 6 h (the end point of the reaction is monitored by TLC). After completion of the reaction, water was added to quench, and the liquids were separated. The aqueous phase was extracted three times with ethyl acetate and the organic phase was washed with water. The resultant was concentrated to dryness and purified through column. The product was dissolved in water, and a 1 mol/L aqueous solution of NaOH was slowly added dropwise until the pH of the system was adjusted to 10, and the aqueous phase was recovered and concentrated to dryness. As a result, 1.8 g (1.75 mmol) of N,N,N′,N′-dodecyl tetrasubstituted diphenyl ether sulfonate as a brown viscous product was obtained.

An infrared spectrum of N,N,N′,N′-dodecyl tetrasubstituted diphenyl ether sulfonate

(18) With respect to FIG. 2, it can be seen from the spectrum analysis that:

(19) 2946, 2869 are CH.sub.3, CH.sub.2 extensional vibration peaks; 1610, 1591, 1507, 1450 are vibrational peaks of the benzene ring skeleton; 873, 828 are characteristic peaks of para-substitution of benzene ring; 1274, 1241 are C—N extensional vibration peaks; 1100, 1049 are C—O extensional vibration peaks; 1091 is a S═O extensional vibration peak; 719 is a (CH.sub.2).sub.n (n≥4) plane swinging vibration peak; and 622 is a S—O extensional vibration peak.

A nuclear magnetic hydrogen spectrum of N,N,N′,N′-dodecyl tetrasubstituted diphenyl ether sulfonate

(20) With respect to FIG. 3, it can be seen from the spectrum analysis that:

(21) .sup.1-NMR (400 MHz, CDCl.sub.3): δ: 0.82-0.99 [3H, CH.sub.3CH.sub.2], 1.12-1.29 [16H, CH.sub.3(CH.sub.2).sub.8CH.sub.2CH.sub.2], 1.46-1.69 [2H, (CH.sub.2).sub.10CH.sub.2CH.sub.2N], 3.19-3.24 [2H, (CH.sub.2).sub.10CH.sub.2CH.sub.2N], 6.60-6.64 [1H, NCCH], 6.88-6.91 [1H, OCCH].

Surfactant Activity Determination of N,N,N′,N′-dodecyl tetrasubstituted diphenyl ether sulfonate

(22) The ability of surfactant to reduce the surface tension of water is an important parameter to evaluate its surface activity. The surface tension of aqueous solution of target aqueous solution at different concentration at 25° C. is determined by a method of hanging plate, and a concentration dependent curve (FIG. 4) was made for the surface tension of an aqueous solution of Gemini surfactant of N,N,N′,N′-dodecyl tetrasubstituted diphenyl ether sulfonate. From this curve, the surface activity parameters of the Gemini surfactant can be obtained, the critical micelle concentration cmc is 0.016 wt %, and the surface tension γ.sub.cmc at the critical micelle concentration is 23 mN/m.

EXAMPLE 1

(23) This example provides a core-shell structured anionic nano microemulsion system and a preparation method thereof. The main preparation steps and test results are as follows:

(24) (1) In parts by weight, 5 parts of xylene, 45 parts of anionic Gemini surfactant of N,N,N′,N′-dodecyl tetrasubstituted diphenyl ether sulfonate, 15.5 parts of butanol, and 34.5 parts of water are weighed and put into reactor, and mixed under agitation at 300 rpm, until completely dissolved, and a homogeneous mixed solution is obtained.

(25) (2) In parts by weight, 0.2 parts of the above homogeneous mixed solution and 99.8 parts of water were taken, and mixed under agitation at 300 rpm in a reactor, until completely dissolved, to obtain a core-shell structured anionic nano microemulsion system. The effective concentration thereof is 0.13%, the appearance is uniform and transparent, and it is stable for a long time.

(26) (3) The initial average particle size of the microemulsion was determined to be 8.0 nm by dynamic light scattering (BI-200SM, Brookhaven) at 90°. After stabilization for 22 days, the average particle size was 152.8 nm (see FIG. 5).

EXAMPLE 2

(27) This example provides a core-shell structured anionic nano microemulsion system and a preparation method thereof. The main preparation steps and test results are as follows:

(28) (1) In parts by weight, 10 parts of pyrrolidone, 50 parts of anionic Gemini surfactant of N,N,N′,N′-dodecyl tetrasubstituted diphenyl ether sulfonate, 20 parts of isopropanol, and 20 parts of water are weighed and put into reactor, and mixed under agitation at 300 rpm, until completely dissolved, and a homogeneous mixed solution is obtained.

(29) (2) In parts by weight, 0.2 parts of the above homogeneous mixed solution and 99.8 parts of water were taken, and mixed under agitation at 300 rpm in a reactor, until completely dissolved, to obtain a core-shell structured anionic nano microemulsion system. The effective concentration thereof is 0.16%, the appearance is uniform and transparent, and it is stable for a long time.

(30) (3) The initial average particle size of the microemulsion was determined to be 12.1 nm by dynamic light scattering (BI-200SM, Brookhaven) at 90°. After stabilization for 22 days, the average particle size was 267.0 nm (see FIG. 6).

EXAMPLE 3

(31) This example provides a core-shell structured anionic nano microemulsion system and a preparation method thereof. The main preparation steps and test results are as follows:

(32) (1) In parts by weight, 5 parts of thiophene, 45 parts of anionic Gemini surfactant of N,N,N′,N′-dodecyl tetrasubstituted diphenyl ether sulfonate, 20 parts of ethanol, and 30 parts of water are weighed and put into reactor, and mixed under agitation at 300 rpm, until completely dissolved, and a homogeneous mixed solution is obtained.

(33) (2) In parts by weight, 0.3 parts of the above homogeneous mixed solution, 98.7 parts of water and 1 part of NaCl were taken, and mixed under agitation at 300 rpm in a reactor, until completely dissolved, to obtain a core-shell structured anionic nano microemulsion system. The effective concentration thereof is 0.21%, the appearance is uniform and transparent, and it is stable for a long time.

(34) (3) The initial average particle size of the microemulsion was determined to be 66.5 nm by dynamic light scattering (BI-200SM, Brookhaven) at 90°. After stabilization for 22 days, the average particle size was 285.6 nm (see FIG. 7).

EXAMPLE 4

(35) This Example provides a core-shell structured anionic nano microemulsion system and a preparation method thereof. The main preparation steps and test results are as follows:

(36) (1) In parts by weight, 30 parts of α-pinene, 50 parts of anionic Gemini surfactant of N,N,N′,N′-dodecyl tetrasubstituted diphenyl ether sulfonate and 20 parts of pentanol were taken, and mixed under agitation at 300 rpm in a reactor, until completely dissolved, to obtain a homogeneous mixed solution.

(37) (2) In parts by weight, 0.1 part of the above homogeneous mixed solution, 94.9 parts of water, 5 parts of NaCl were taken, and mixed under agitation at 300 rpm in a reactor, until completely dissolved, to obtain a core-shell structured anionic nano microemulsion system. The effective concentration thereof is 0.1%, the appearance is uniform and transparent, and it is stable for a long time. The transmission electron microscopy (HT7700, HITACHI, Japan) proved that the microemulsion system at a mass concentration of 0.1% has a spherical core-shell structure (see FIG. 8).

(38) (3) In parts by weight, 0.3 part of the above homogeneous mixed solution, 94.7 parts of water, 5 parts of NaCl were taken, and mixed under agitation at 300 rpm in a reactor, until completely dissolved, to obtain a core-shell structured anionic nano microemulsion system. The effective concentration thereof is 0.3%, the appearance is uniform and transparent, and it is stable for a long time. The transmission electron microscopy (HT7700, HITACHI, Japan) proved that the microemulsion system at a mass concentration of 0.3% has a spherical core-shell structure (see FIG. 9).

(39) (4) In dynamic light scattering measurement (Brookhaven BI-200SM) at 90°, the initial average particle diameters of anionic nano microemulsions with mass concentrations of 0.1% and 0.3% were determined as 24.0 nm and 15.1 nm, respectively (see FIGS. 10 and 11), and the particle size distribution was narrow. After stabilization for 30 days, the average particle size was 110.5 nm, and 32.6 nm (see FIG. 12). That is, both the anionic nano microemulsion system have a particle size of less than 40 nm. The particle size of the anionic nano microemulsion at a mass concentration of 0.3% is always smaller than 40 nm, with minimal variation and excellent stability, showing obvious superiority.

EXAMPLE 5

(40) This Example evaluates the main properties of the core-shell structured anionic nano microemulsion system, and the specific results are as follows:

(41) (1) By using a TX500C rotary drop interface force meter, the interfacial tension of 0.1% by mass and 0.3% by mass of anionic nano microemulsion system prepared in Example 4 with kerosene at 80° C. were determined as 0.012 mN/m and 0.009 mN/m, respectively. The experimental results show that the anionic nano microemulsion system has ultra-low interfacial tension, showing obvious superiority.

(42) (2) By using a TX500C rotary drop interface force meter, the interfacial tension of 0.1% by mass and 0.3% by mass of anionic nano microemulsion system prepared in Example 4 with a certain crude oil in Xinjiang (apparent viscosity is 18 mPa.Math.s) at 80° C. were determined as 0.1 mN/m and 0.08 mN/m, respectively. The experimental results show that the anionic nano microemulsion system has ultra-low interfacial tension with crude oil, showing obvious superiority.

(43) (3) By using a rheometer (RS600, Huck, Germany), the effects of 0.1% by mass and 0.3% by mass of anionic nano microemulsion system prepared in Example 4 on reducing the viscosity of certain crude oil in Xinjiang were determined (see FIG. 13). The experimental results show that the anionic nano microemulsion system has an average viscosity reduction efficiency of 40% for a certain crude oil in Xinjiang, which is a good viscosity-reducing effect and shows obvious superiority.

(44) It will be apparent that the above-described examples of the present invention are merely for clearly illustration of the present invention and are not intended to limit the embodiments of the present invention. To those of ordinary skill in the art, other different forms of changes or variations may also be made on the basis of the above description. It is unable to exhaust all implementations, and the obvious changes or variations that are introduced from the technical solution of the present invention are still within the scope of the present invention.