A method for preparing nano sulfur particles

Abstract

The present invention discloses a preparation method of nano sulfur particles, which comprises the following steps: (1) adding a stabilizer into purified water, stirring and dissolving it, then adding a mixture of sulfur and sodium sulfide nonahydrate into it, stirring and dissolving it, and then adding a thickener into it, stirring and dissolving it; wherein, the stabilizer is one of sodium carbonate, sodium hydroxide, sodium bicarbonate or a mixture of multiple kinds in any proportion; (2) uniformly adding an oxidant into the mixed system obtained in step (1), stirring, and stopping stirring and ending the reaction when the mixed system changes from yellow transparent to white emulsion; (3) transferring the reaction solution obtained in step (2), standing and then centrifuging, recycling the separated liquid for standby, washing the separated product with purified water, repeating the above standing, centrifuging and washing operations twice, drying the separated product under vacuum, and pulverizing it with a ball mill to obtain nano sulfur particles. The method provided by the present invention has mild reaction conditions and is easy to control.

Description

Technical Field

[0001] The present invention belongs to the technical field of nanomaterials, and particularly relates to a method for preparing nano sulfur particles. Background Art

[0002] Nanomaterials are an emerging and rapidly developing material science. The attractive characteristics of nanomaterials in terms of structure, physical and chemical properties have attracted the strong interest of many scientists.

[0003] Elemental sulfur is not only an important chemical raw material, but also an inorganic bactericide and insecticide that is basically non-toxic, bactericidal and insecticidal. Sulfur soap in daily life and lime sulfur mixture used to control wheat rust, powdery mildew, rice blast, and red spider mites on cotton and fruit trees are well-known sulfur-containing insecticidal and antibacterial products. Sulfur-containing bactericidal and antibacterial materials are non-toxic, have broad-spectrum bactericidal and antibacterial properties, long service life, do not produce drug resistance, and also have good heat resistance. Especially nano-bactericides, in addition to the common antibacterial effects, also have low toxicity, easy dispersion and thermal stability. For humans and animals, there will only be very minor or almost no chronic or acute diseases; and the unique trace active inorganic component release system can ensure no impact on the environment. Therefore, it has attracted much attention.

[0004] Sulfur has a very wide range of uses. After purification, impurity removal and other processing procedures, it can be used in various production fields such as the preparation of sulfuric acid, chemical fiber, chemical fertilizer, synthetic rubber, and medicine.

[0005] Using nanotechnology, elemental sulfur can be processed into powders with an average particle diameter of 20nm - 50nm, and supplemented with physical and chemical conditions to control the shape of nanomaterials by artificial methods. Sulfur nanoparticles, sulfur nanowires, and nanorods with a nanostructured system all have quantum size effects and surface effects, and have excellent properties in terms of light, electricity, magnetism, catalysis, etc. It can improve the problems of large particle size of ordinary sulfur (generally about 50μm), causing skin roughness and unsatisfactory bactericidal effects. Elemental sulfur nanomaterials have broad application prospects in the fields of electronics, biology, coatings, pharmaceuticals, etc.

[0006] Chinese Patent CN1636865A discloses a preparation method of nano sulfur. The ultrasonic solvent conversion method is adopted. Under ultrasonic conditions, elemental sulfur is dissolved in an organic solvent. By gradually adding another polar solvent to change the polarity of the system, under the action of ultrasonic energy, it precipitates and self-assembles to form elemental sulfur nanowires. The inventive method has a simple process. Compared with the gas-phase method process, it has high efficiency, mild conditions, easy control of particle size, and the solvent in the preparation process can be recycled, providing a new way for the preparation of sulfur nano materials. However, this method dissolves elemental sulfur in ethanol or acetone solvents. Organic solvents are flammable and toxic liquids. Ethyl mercaptan liquid, mesityl oxide, etc. generated after combining with sulfur are all highly volatile and highly toxic substances, requiring high production environment and production safety requirements, and cannot be mass-produced.

[0007] Chinese Patent CN 105355894 A discloses a preparation method of nano sulfur particles, including four steps of preparing a sulfur elemental solution, recrystallization, drying, and pulverization. First, a saturated solution of sulfur at temperature T1 is prepared, and then the saturated solution is cooled to T2 (T2 < T1) to gradually precipitate sulfur to obtain nano sulfur particles; maintaining the temperature at T2, separating the nano sulfur particles from the solution by means such as filtration and centrifugation, and then drying, simple ball milling or mechanical pulverization to obtain nano sulfur particles. This process is simple and easy to operate. However, organic solvents are used. Organic solvents are flammable and toxic liquids. Substances generated after combining with sulfur are highly volatile and highly toxic substances, requiring high production environment and production safety requirements, with a complex process and high requirements for production equipment, and cannot be mass-produced.

[0008] In the preparation methods of sulfur nanocrystals, the currently reported methods are only the high-temperature gas-phase solidification method. This method needs to be carried out under high temperature and inert gas protection, with high requirements for the production environment. Therefore, it is necessary to find a simple and easy-to-operate preparation method of nano sulfur. Summary of the Invention

[0009] Aiming at the defects of the prior art, the present invention provides a preparation method of nano sulfur particles, with mild reaction conditions and easy control.

[0010] A preparation method of nano sulfur particles includes the following steps:

[0011] (1) Add a stabilizer to purified water, stir and dissolve it, then add a mixture of sulfur and sodium sulfide nonahydrate to it, stir and dissolve it, and then add a thickener to it, stir and dissolve it; wherein, the stabilizer is one of sodium carbonate, sodium hydroxide, sodium bicarbonate or a mixture of multiple kinds in any proportion;

[0012] (2) Uniformly add an oxidant to the mixed system obtained in step (1) within 30 - 50 minutes, stir. When the mixed system changes from yellow transparent to white emulsion, stop stirring, and the reaction ends;

[0013] (3) Transfer the reaction solution obtained in step (2), let it stand for 2 - 3 h and then centrifuge. The separated solution is recovered for standby. The obtained product is washed with purified water, and the above operations of standing, centrifuging and washing are repeated twice. The obtained product is dried in vacuum and pulverized by a ball mill to obtain nano sulfur particles.

[0014] Preferably, in steps (1) and (2), the weight ratio of purified water, stabilizer, mixture of sulfur and sodium sulfide nonahydrate, thickener, and oxidant is (100 - 300):(1 - 10):(10 - 20):(1 - 20):(150 - 400).

[0015] Preferably, the mass ratio of the sulfur to the sodium sulfide nonahydrate is 1:(8 - 15).

[0016] Preferably, the thickener is one of polyvinylpyrrolidone K30, polyethylene glycol, and carboxyethyl cellulose or a mixture of multiple ones in any proportion.

[0017] Preferably, the oxidant is hydrogen peroxide solution or sodium percarbonate.

[0018] Preferably, the concentration of the hydrogen peroxide solution is 20 - 50 wt%.

[0019] Preferably, the stirring speed in step (2) is 100 - 300 r / min.

[0020] Preferably, the conditions for vacuum drying are vacuum drying at 40 - 50 °C for 12 - 15 h.

[0021] In the present invention, when the oxidant is sodium percarbonate, the sodium percarbonate can be added in the form of sodium percarbonate solution or sodium percarbonate, and its addition amount is calculated based on the effective content of sodium percarbonate.

[0022] Advantages of the present invention:

[0023] (1) In the method provided by the present invention, sulfur is dissolved in the sodium sulfide solution to form polysulfide sodium. The thickener serves as a support for nano sulfur monomers, making the particle size distribution of nano sulfur more uniform. The oxidant can greatly increase the purity of the product nano sulfur and at the same time reduce the difficulty of product separation;

[0024] (2) The reaction of the present invention is a self-heating reaction, which will spontaneously accelerate the reaction rate and increase the yield;

[0025] (3) The reaction equipment required by the present invention is relatively simple, and an ordinary high-speed reaction kettle can provide good reaction conditions;

[0026] (4) The process of the present invention is simple, easy to operate, low in cost, with high product purity and good dispersibility. The liquid separated during the preparation process can be recycled and reused. Description of the Drawings

[0027] Figure 1 Transmission electron micrograph of nano sulfur. Detailed Description of the Invention

[0028] Example 1

[0029] A method for preparing nano sulfur particles, comprising the following steps:

[0030] (1) Add 1 g of sodium carbonate to 100 g of purified water, stir to dissolve, then add a mixture of 10 g of sulfur and sodium sulfide nonahydrate, stir to dissolve, and then add 1 g of polyvinylpyrrolidone K30, stir to dissolve; wherein, the weight ratio of sulfur to sodium sulfide nonahydrate is 1:10;

[0031] (2) Slowly add 350 g of 20 wt% hydrogen peroxide solution to the mixed system obtained in step (1) within 30 min, stir at a speed of 100 rpm, and stop stirring when the mixed system changes from yellow transparent to white emulsion, and the reaction ends;

[0032] (3) Transfer the reaction solution obtained in step (2), let it stand for 2 h and then centrifuge to separate. The separated liquid is recovered for standby. The product obtained by separation is washed with purified water, and the above-mentioned standing, centrifuging and washing operations are repeated 2 times. The product obtained by separation is vacuum dried at 40 °C for 12 h and pulverized by a ball mill to obtain nano sulfur particles; perform transmission electron microscopy, see Figure 1 , it can be seen that the prepared nano sulfur particles are rod-shaped, with a diameter of about 35.2 - 53.3 nm and a length of about 200 nm.

[0033] Example 2

[0034] A method for preparing nano sulfur particles, comprising the following steps:

[0035] (1) Add 10 g of sodium hydroxide to 300 g of purified water, stir to dissolve, then add a mixture of 20 g of sulfur and sodium sulfide nonahydrate, stir to dissolve, and then add 20 g of polyethylene glycol, stir to dissolve; wherein, the weight ratio of sulfur to sodium sulfide nonahydrate is 1:8;

[0036] (2) Slowly add 200 g of 35 wt% hydrogen peroxide solution to the mixed system obtained in step (1) within 30 min, stir at a speed of 300 rpm, and stop stirring when the mixed system changes from yellow transparent to white emulsion, and the reaction ends;

[0037] (3) Transfer the reaction solution obtained in step (2), let it stand for 2 h and then centrifuge to separate. The separated liquid is recovered for standby. The product obtained by separation is washed with purified water, and the above operations of standing, centrifuging and washing are repeated 2 times. The product obtained by separation is vacuum-dried at 50 °C for 15 h and then pulverized by a ball mill to obtain nano sulfur particles. Observed by transmission electron microscopy, the nano sulfur particles are rod-shaped, with a diameter of about 75.7 - 150.3 nm and a length of about 500 nm.

[0038] Example 3

[0039] A method for preparing nano sulfur particles, comprising the following steps:

[0040] (1) Add 5 g of sodium bicarbonate to 200 g of purified water, stir to dissolve, then add a mixture of 10 g of sulfur and sodium sulfide nonahydrate thereto, stir to dissolve, and then add 10 g of carboxyethyl cellulose thereto, stir to dissolve; wherein, the weight ratio of sulfur to sodium sulfide nonahydrate is 1:15;

[0041] (2) Slowly add 150 g of 50 wt% hydrogen peroxide solution to the mixed system obtained in step (1) within 50 min, stir at a speed of 200 rpm, and stop stirring when the mixed system changes from yellow transparent to white emulsion, and the reaction ends;

[0042] (3) Transfer the reaction solution obtained in step (2), let it stand for 3 h and then centrifuge to separate. The separated liquid is recovered for standby. The product obtained by separation is washed with purified water, and the above operations of standing, centrifuging and washing are repeated 2 times. The product obtained by separation is vacuum-dried at 50 °C for 15 h and then pulverized by a ball mill to obtain nano sulfur particles. Observed by transmission electron microscopy, the nano sulfur particles are rod-shaped, with a diameter of about 50.5 - 90.7 nm and a length of about 350 nm.

[0043] Example 4

[0044] A method for preparing nano sulfur particles, comprising the following steps:

[0045] (1) Add 8 g of stabilizer to 200 g of purified water, stir to dissolve, then add a mixture of 15 g of sulfur and sodium sulfide nonahydrate thereto, stir to dissolve, and then add 5 g of thickener thereto, stir to dissolve; wherein, the weight ratio of sulfur to sodium sulfide nonahydrate is 1:10; the stabilizer is a mixture of sodium carbonate and sodium bicarbonate with an equal mass ratio; the thickener is a mixture of polyvinylpyrrolidone K30 and carboxyethyl cellulose with an equal mass ratio;

[0046] (2) Slowly add 350 g of 30 wt% hydrogen peroxide solution to the mixed system obtained in step (1) within 50 min, stir at a speed of 200 rpm, and stop stirring when the mixed system changes from yellow transparent to white emulsion, and the reaction ends;

[0047] (3) Transfer the reaction solution obtained in step (2), let it stand for 2 h and then centrifuge. The separated solution is recovered for reuse. The obtained product is washed with purified water, and the above operations of standing, centrifuging and washing are repeated twice. The obtained product is dried in vacuum at 50 °C for 15 h and then pulverized by a ball mill to obtain nano sulfur particles. Observed by transmission electron microscopy, the nano sulfur particles are rod-shaped, with a diameter of about 39.2 - 78.9 nm and a length of about 300 nm.

[0048] Example 5

[0049] A preparation method of nano sulfur particles, comprising the following steps:

[0050] (1) Add 10 g of stabilizer to 300 g of purified water, stir to dissolve, then add a mixture of 10 g of sulfur and sodium sulfide nonahydrate thereto, stir to dissolve, and then add 8 g of thickener thereto, stir to dissolve; wherein, the weight ratio of sulfur to sodium sulfide nonahydrate is 1:10; the stabilizer is a mixture of sodium carbonate, sodium bicarbonate and sodium hydroxide; the thickener is a mixture of polyvinylpyrrolidone K30 and polyethylene glycol in an equal mass ratio;

[0051] (2) Slowly add 400 g of 50 wt% sodium percarbonate solution to the mixed system obtained in step (1) within 30 min, stir at a rotation speed of 200 rpm, and stop stirring when the mixed system changes from yellow transparent to white emulsion, and the reaction ends;

[0052] (3) Transfer the reaction solution obtained in step (2), let it stand for 2 h and then centrifuge. The separated solution is recovered for reuse. The obtained product is washed with purified water, and the above operations of standing, centrifuging and washing are repeated twice. The obtained product is dried in vacuum at 50 °C for 15 h and then pulverized by a ball mill to obtain nano sulfur particles. Observed by transmission electron microscopy, the nano sulfur particles are rod-shaped, with a diameter of about 50.5 - 130.7 nm and a length of about 270 nm.

[0053] Example 6

[0054] A preparation method of nano sulfur particles, comprising the following steps:

[0055] (1) Add 10 g of stabilizer to 300 g of purified water, stir to dissolve, then add a mixture of 20 g of sulfur and sodium sulfide nonahydrate thereto, stir to dissolve, and then add 20 g of thickener thereto, stir to dissolve; wherein, the weight ratio of sulfur to sodium sulfide nonahydrate is 1:15; the stabilizer is a mixture of sodium carbonate, sodium bicarbonate and sodium hydroxide; the thickener is a mixture of polyvinylpyrrolidone K30, polyethylene glycol and carboxyethyl cellulose in an equal mass ratio;

[0056] (2) Add 400 g of sodium percarbonate into the mixed system obtained in step (1) at a uniform speed within 50 min, stir at a rotation speed of 200 rpm, and stop stirring when the mixed system changes from yellow transparent to white emulsion, and the reaction ends;

[0057] (3) Transfer the reaction solution obtained in step (2), let it stand for 3 h and then perform centrifugal separation. The separated solution is recovered for standby. The product obtained by separation is washed with purified water, and the above-mentioned standing, centrifuging and washing operations are repeated 2 times. The product obtained by separation is vacuum dried at 50 °C for 15 h and pulverized by a ball mill to obtain nano sulfur particles; Observed by transmission electron microscopy, the nano sulfur particles are rod-shaped, with a diameter of about 40.6 - 165.3 nm and a length of about 173 nm.

[0058] Performance detection

[0059] 1. The sulfur obtained by the present invention is detected according to GB 3150 - 2010, and the results are shown in Table 1.

[0060] Table 1 Detection data of sulfur

[0061] 。

Claims

1. A method for preparing nano sulfur particles, characterized in that: It includes the following steps: (1) Add a stabilizer to purified water, stir to dissolve, then add a mixture of sulfur and sodium sulfide nonahydrate to it, stir to dissolve, and then add a thickener to it, stir to dissolve; wherein, the stabilizer is one of sodium carbonate, sodium hydroxide, sodium bicarbonate or a mixture of multiple kinds in any proportion; (2) Uniformly add an oxidant to the mixed system obtained in step (1) within 30 - 50 min, stir, and stop stirring when the mixed system changes from yellow transparent to white emulsion, and the reaction ends; (3) Transfer the reaction solution obtained in step (2), let it stand for 2 - 3 h and then centrifuge, recycle the separated liquid for standby, wash the separated product with purified water, repeat the above operations of standing, centrifuging and washing 2 times, vacuum dry the separated product, and pulverize it with a ball mill to obtain nano sulfur particles; The oxidant is hydrogen peroxide solution or sodium percarbonate; In steps (1) and (2), the weight ratio of purified water, stabilizer, mixture of sulfur and sodium sulfide nonahydrate, thickener, and oxidant is (100 - 300):(1 - 10):(10 - 20):(1 - 20):(150 - 400).

2. The method for preparing nano sulfur particles according to claim 1, characterized in that: The mass ratio of sulfur to sodium sulfide nonahydrate is 1:(8 - 15).

3. The method for preparing nano sulfur particles according to claim 2, characterized in that: The thickener is one of polyvinylpyrrolidone K30, polyethylene glycol, carboxyethyl cellulose or a mixture of multiple kinds in any proportion.

4. The method for preparing nano sulfur particles according to claim 3, characterized in that: The concentration of the hydrogen peroxide solution is 20 - 50 wt%.

5. The method for preparing nano sulfur particles according to claim 3, characterized in that: The stirring speed in step (2) is 100 - 300 r / min.

6. The method for preparing nano sulfur particles according to claim 5, characterized in that: The conditions for vacuum drying are vacuum drying at 40 - 50 °C for 12 - 15 h.

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