Calcium sulfate nano-particles with high dispersibility in water-in-oil emulsion and preparation method of calcium sulfate nano-particles

Abstract

The invention discloses calcium sulfate nanoparticles with high dispersibility in a water-in-oil emulsion and a preparation method thereof, and the preparation method comprises the following steps: (1) dissolving water, disodium ethylene diamine tetraacetate and ammonium sulfate in glycerol to obtain a solution I; (2) dissolving calcium chloride and a silane coupling agent in glycerol to obtain a solution II; (3) heating the solution I and the solution II, mixing, stirring the mixture for reaction, and centrifugally filtering to obtain calcium sulfate nanoparticles; (4) washing the obtained calcium sulfate nanoparticles in a mixture of water and acetone to remove glycerol, ethylene diamine tetraacetic acid and the silane coupling agent; and (5) drying the cleaned calcium sulfate nanoparticles in a drying oven to remove water and acetone. According to the invention, the dispersibility of the nanoparticles in the water-in-oil emulsion is enhanced, the separation time is shortened, and the energy consumption is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of oil-water separation, and in particular relates to calcium sulfate nanoparticles with high dispersibility in oil-in-water emulsion and a preparation method thereof. Background Art

[0002] A large amount of water-in-oil emulsions are generated during oil extraction and industrial emissions. Due to the high degree of emulsification, these emulsions are difficult to effectively treat with traditional separation methods, resulting in environmental pollution and waste of resources. In addition, water-in-oil emulsions will increase the load on equipment, cause corrosion and scaling on metal surfaces, and affect the service life of equipment. Therefore, water-in-oil emulsion separation technology is not only a key means to solve environmental pollution and protect the ecological environment, but also an important way to improve resource utilization efficiency and reduce production costs. With the acceleration of industrialization and the improvement of environmental awareness, the research and application of water-in-oil emulsion separation technology will receive more and more attention.

[0003] Regarding the separation technology of water-in-oil emulsion, the inventor of the present invention previously applied for invention patents CN105771321A, a method for separating water-in-oil emulsion with inorganic crystals, and CN117923522A, a method for removing trace water from water-in-oil emulsion with anhydrous sodium sulfate crystals and a preparation method and a regeneration method thereof. The trace water in the emulsion is fixed in the crystals through the fixed lattice structure of the crystals, and then the crystals are separated from the oil to achieve the purpose of removing water.

[0004] However, since these micro-nanoparticles have extremely good hydrophilicity, their dispersibility in oil-in-water emulsions is poor. In the above-mentioned prior patents, mechanical stirring (0.5h) and heating stirring (20-100°C / 0.5-2h) are required to fully disperse the micro-nanoparticles, which makes the separation process time-consuming and energy-intensive, and there is a risk of changing the properties of the oil by heating. Summary of the invention

[0005] In view of this, the object of the present invention is to provide a calcium sulfate nanoparticle with high dispersibility in an oil-in-water emulsion and a preparation method thereof, so as to enhance the dispersibility of the nanoparticle in the oil-in-water emulsion, reduce the separation time and reduce the energy consumption.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention discloses a method for preparing calcium sulfate nanoparticles with high dispersibility in a water-in-oil emulsion, comprising the following steps:

[0008] (1) dissolving water, disodium ethylenediaminetetraacetate and ammonium sulfate in glycerol to obtain solution I;

[0009] (2) dissolving calcium chloride and a silane coupling agent in glycerol to obtain a solution II;

[0010] (3) heating solution I and solution II and mixing them, stirring the mixture for reaction, and then centrifugally filtering to obtain calcium sulfate nanoparticles;

[0011] (4) washing the obtained calcium sulfate nanoparticles in a mixture of water and acetone to remove glycerol, disodium ethylenediaminetetraacetate and silane coupling agent;

[0012] (5) Drying the washed calcium sulfate nanoparticles in an oven to remove water and acetone.

[0013] As a preferred technical solution, in step (1), the mass ratio of disodium ethylenediaminetetraacetate to ammonium sulfate is 1:5 to 1:5.5.

[0014] As a preferred technical solution, in step (2), the mass ratio of the silane coupling agent to calcium chloride is 1:10 to 1:100.

[0015] As a preferred technical solution, in step (2), the mass ratio of the silane coupling agent to calcium chloride is 1:20 to 1:40.

[0016] As a preferred technical solution, in step (3), solution I and solution II are mixed in a molar ratio of calcium chloride to ammonium sulfate of 1:1.

[0017] As a preferred technical solution, in step (3), the heating temperature of solution I and solution II is 80-100° C., the reaction temperature is 80-100° C., and the stirring rate is 300-500 rpm.

[0018] As a preferred technical solution, in step (4), the volume ratio of water to acetone is 1:5 to 1:10.

[0019] As a preferred technical solution, in step (5), the drying temperature is 50 to 80° C. and the drying time is 1 to 3 hours.

[0020] The invention also discloses calcium sulfate nanoparticles prepared by the preparation method.

[0021] The invention also discloses a method for removing trace water in an oil-in-water emulsion, wherein the calcium sulfate nanoparticles are added into the oil-in-water emulsion, fully stirred, and separated to obtain clean oil and calcium sulfate dihydrate.

[0022] The beneficial effects of the present invention are:

[0023] The invention synthesizes monodisperse calcium sulfate nanoparticles through a crystallization process mediated by disodium ethylenediaminetetraacetate, and adds a silane coupling agent into a solution II. The silane coupling agent reacts with hydroxyl groups on the surface of the calcium sulfate particles, thereby giving the calcium sulfate nanoparticles lipophilicity, thereby promoting the dispersion of the calcium sulfate nanoparticles in an oil-in-water emulsion.

[0024] The surface modified calcium sulfate nanoparticles obtained by the method of the present invention have significantly higher dispersibility than unmodified calcium sulfate nanoparticles, can significantly shorten the time of the oil-water separation process, and the reaction process does not require heating, effectively reducing the energy consumption of the oil-water separation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to make the purpose, technical solution and beneficial effects of the present invention clearer, the present invention provides the following drawings for illustration:

[0026] Figure 1 a is a photograph of the unmodified calcium sulfate granules powder prepared in Comparative Example 1 of the present invention just added into the emulsion;

[0027] Figure 1 b is a photograph of the unmodified calcium sulfate granules prepared in Comparative Example 1 of the present invention after being added to the emulsion for 2 minutes;

[0028] Figure 2 a is a photograph of the modified calcium sulfate granules powder prepared in Example 1 of the present invention just added into the emulsion;

[0029] Figure 2 b is a photograph of the modified calcium sulfate granules powder prepared in Example 1 of the present invention 10 seconds after being added to the emulsion;

[0030] Figure 3 a is a photograph of the modified calcium sulfate granules powder prepared in Example 1 of the present invention, added to the emulsion and stirred for 10 minutes, and the solid was separated to obtain the oil;

[0031] Figure 3 b is a microscopic image of the oil obtained after adding the modified calcium sulfate granule powder prepared in Example 1 of the present invention to the emulsion and stirring for 10 minutes and separating the solid. DETAILED DESCRIPTION

[0032] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0033] The methods used in the following examples are all conventional methods unless otherwise specified. The materials or reagents required in the following examples are all purchased from the market unless otherwise specified.

[0034] Embodiment 1:

[0035] A method for preparing calcium sulfate nanoparticles with high dispersibility in a water-in-oil emulsion comprises the following steps:

[0036] (1) Dissolve 10 ml of deionized water, 1 g of disodium ethylenediaminetetraacetate, and 5 g of ammonium sulfate in 200 ml of glycerol to obtain solution I;

[0037] (2) dissolving 4.2 g of calcium chloride and 0.4 g of a silane coupling agent in 50 ml of glycerol to obtain a solution II;

[0038] (3) heating solution I and solution II to 90° C., then quickly injecting solution II into solution I, stirring the mixture at 90° C. at a speed of 500 rpm for reaction, and then centrifugally filtering to obtain calcium sulfate nanoparticles;

[0039] (4) washing the obtained calcium sulfate nanoparticles three times in a mixture of water and acetone (volume ratio 1:8) to remove glycerol, disodium ethylenediaminetetraacetate and silane coupling agent;

[0040] (5) The washed calcium sulfate nanoparticles were dried in an oven at 80° C. for 2 h to remove water and acetone.

[0041] Embodiment 2:

[0042] A method for preparing calcium sulfate nanoparticles with high dispersibility in an oil-in-water emulsion, the difference from Example 1 is that the mass of the silane coupling agent in step (2) is 0.3 g.

[0043] Embodiment 3:

[0044] A method for preparing calcium sulfate nanoparticles with high dispersibility in an oil-in-water emulsion, the difference from Example 1 being that the mass of the silane coupling agent in step (2) is 0.2 g.

[0045] Embodiment 4:

[0046] A method for preparing calcium sulfate nanoparticles with high dispersibility in an oil-in-water emulsion, the difference from Example 1 is that the mass of the silane coupling agent in step (2) is 0.1 g.

[0047] Embodiment 5:

[0048] A method for preparing calcium sulfate nanoparticles with high dispersibility in an oil-in-water emulsion, the difference from Example 1 being that the mass of the silane coupling agent in step (2) is 0.08 g.

[0049] Embodiment 6:

[0050] A method for preparing calcium sulfate nanoparticles with high dispersibility in an oil-in-water emulsion, the difference from Example 1 is that the mass of the silane coupling agent in step (2) is 0.04 g.

[0051] Comparative Example 1

[0052] A method for preparing calcium sulfate nanoparticles with high dispersibility in a water-in-oil emulsion, which differs from Example 1 in that no silane coupling agent is added in step (2).

[0053]

Preparation of water-in-oil emulsion

[0054] 1 ml of deionized water was added to 99 ml of transformer oil, magnetically stirred at 500 rpm for 2 h, and then ultrasonicated at a frequency of 45 kHz for 3 h to obtain a stable white water-in-oil emulsion with a water content of 1%.

[0055]

Oil-water separation performance test

[0056] Take 10 ml of the emulsion and put it in a sample bottle, weigh an appropriate amount of calcium sulfate nanoparticles according to the water capacity of the calcium sulfate nanoparticles, add the calcium sulfate nanoparticles into the sample bottle containing the emulsion, then perform magnetic stirring at 1500 rpm for a certain period of time to allow the calcium sulfate nanoparticles to fully react with water, centrifuge at 5000 rpm for 3 minutes after the reaction to separate the liquid from the solid, take the supernatant to measure the water content in the oil, and calculate the oil-water separation efficiency according to the formula: separation efficiency = (initial water content-water content after reaction) / initial water content×100%.

[0057]

Test results

[0058] The test results are shown in Table 1

[0059] Table 1 Comparison of oil-water separation performance between the examples and the comparative examples

[0060]

[0061] From the data in Table 1, it can be seen that the surface-modified calcium sulfate nanoparticles obtained by the method for preparing calcium sulfate nanoparticles with high dispersibility in oil-in-water emulsions according to the present invention show better dispersibility in the separation process of oil-in-water emulsions than the unmodified calcium sulfate nanoparticles, which is specifically manifested as follows:

[0062] like Figure 1 As shown in the figure, when the unmodified calcium sulfate nanoparticle powder is added to the emulsion, most of the powder floats on the emulsion and gradually sinks into the emulsion after 2 minutes. Figure 2 As shown, when the surface-modified calcium sulfate nanoparticle powder was just added to the emulsion, the powder began to immerse in the emulsion, and after 10 seconds, all the modified calcium sulfate nanoparticle powders were completely immersed in the emulsion. This proves the excellent dispersibility of the surface-modified calcium sulfate nanoparticles in the emulsion, which significantly shortens the stirring time during the oil-water separation process.

[0063] Example 1 only needs 10 minutes of reaction to achieve a stable separation efficiency. The effect after separation is as follows: Figure 3 As shown, the oil product after separation is clear and transparent, and almost no water droplets can be observed in its microscopic image. The separation efficiency reaches 98.10%, which is slightly lower than that of the comparative example, but the reaction time is greatly shortened. The reaction time of Examples 2-4 is shortened to 15 minutes, among which the separation efficiency of Example 2 is slightly lower than that of the comparative example, while the separation efficiency of Examples 3-4 is equivalent to that of the comparative example. Under the premise that the separation efficiency is not reduced, the reaction time of Examples 5-6 is shortened to 20 and 25 minutes respectively. In contrast, the separation process of Comparative Example 1 requires 45 minutes of reaction.

[0064] The above data show that the surface-modified calcium sulfate nanoparticles proposed in the present invention have high dispersibility in the water-in-oil emulsion. The lipophilic property of the silane coupling agent enables the modified calcium sulfate nanoparticles to be quickly dispersed in the emulsion, thereby improving the reaction efficiency and greatly shortening the reaction time.

[0065] The above-described embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or changes made by those skilled in the art based on the present invention are within the protection scope of the present invention. The protection scope of the present invention shall be subject to the claims.

Claims

1. A method for preparing calcium sulfate nanoparticles with high dispersibility in water-in-oil emulsion, characterized in that: The steps include: (1) dissolving water, disodium ethylenediaminetetraacetate and ammonium sulfate in glycerol to obtain solution I; (2) dissolving calcium chloride and a silane coupling agent in glycerol to obtain a solution II; (3) heating solution I and solution II and mixing them, stirring the mixture for reaction, and then centrifugally filtering to obtain calcium sulfate nanoparticles; (4) washing the obtained calcium sulfate nanoparticles in a mixture of water and acetone to remove glycerol, disodium ethylenediaminetetraacetate and silane coupling agent; (5) Drying the washed calcium sulfate nanoparticles in an oven to remove water and acetone.

2. The method for preparing calcium sulfate nanoparticles with high dispersibility in water-in-oil emulsion according to claim 1, characterized in that: In the step (1), the mass ratio of disodium ethylenediaminetetraacetate to ammonium sulfate is 1:5 to 1:5.

5.

3. The method for preparing calcium sulfate nanoparticles with high dispersibility in water-in-oil emulsion according to claim 1, characterized in that: In the step (2), the mass ratio of the silane coupling agent to calcium chloride is 1:10 to 1:

100.

4. The method for preparing calcium sulfate nanoparticles with high dispersibility in water-in-oil emulsion according to claim 3, characterized in that: In the step (2), the mass ratio of the silane coupling agent to calcium chloride is 1:20 to 1:

40.

5. The method for preparing calcium sulfate nanoparticles with high dispersibility in water-in-oil emulsion according to claim 1, characterized in that: In the step (3), solution I and solution II are mixed in a molar ratio of calcium chloride to ammonium sulfate of 1:

1.

6. The method for preparing calcium sulfate nanoparticles with high dispersibility in water-in-oil emulsion according to claim 1, characterized in that: In the step (3), the heating temperature of solution I and solution II is 80-100° C., the reaction temperature is 80-100° C., and the stirring rate is 300-500 rpm.

7. The method for preparing calcium sulfate nanoparticles with high dispersibility in water-in-oil emulsion according to claim 1, characterized in that: In the step (4), the volume ratio of water to acetone is 1:5 to 1:

10.

8. The method for preparing calcium sulfate nanoparticles with high dispersibility in water-in-oil emulsion according to claim 1, characterized in that: In the step (5), the drying temperature is 50 to 80° C. and the drying time is 1 to 3 hours.

9. Calcium sulfate nanoparticles prepared by the preparation method according to any one of claims 1 to 8.

10. A method for removing trace water from a water-in-oil emulsion, characterized in that: the calcium sulfate nanoparticles according to claim 9 are added to the water-in-oil emulsion, stirred sufficiently, and separated to obtain clean oil and calcium sulfate dihydrate.

Images