CN113875775B - Preparation method of all-silicon molecular sieve encapsulated nano silver bactericide - Google Patents

Abstract

The invention belongs to the technical field of bactericide preparation, and in particular relates to a method for preparing a nano-silver bactericide encapsulated by an all-silicon molecular sieve. The present invention forms a nano-silver precursor complex formed of (3-mercaptopropyl) trimethoxysilane and silver nitrate Introduce into the synthesis system of all-silicon molecular sieve, and then encapsulate the nano-silver precursor into the all-silicon molecular sieve through in-situ static crystallization, and finally prepare the all-silicon molecular sieve-encapsulated nano-silver fungicide by high-temperature roasting and hydrogen reduction. On the one hand, the coordination between (3-mercaptopropyl)trimethoxysilane and silver ions is used to prevent the precipitation of silver ions, and the interaction between it and the molecular sieve precursor is used to uniformly disperse the silver ions inside the pores of the molecular sieve. On the other hand, the limited pore size of molecular sieves can also effectively limit the release rate of silver ions, avoid the occurrence of violent release, and achieve the purpose of slow and controlled release, so that it has broad application prospects as a broad-spectrum fungicide.

Description

A kind of preparation method of all-silicon molecular sieve encapsulated nano-silver bactericide

technical field

The invention belongs to the technical field of preparation of nano-silver bactericide, and in particular relates to a method for preparing a nano-silver bactericide encapsulated by an all-silicon molecular sieve.

Background technique

Silver ions have a strong bactericidal effect. Studies have shown that in water or air containing water, the surface of nano-silver will be oxidized and free traces of silver ions, and when the concentration of silver ions reaches 0.01ppm, it will have a good bactericidal effect After the bacteria die, silver ions can be released again to continue to play a bactericidal function. Therefore, nano-silver is a high-quality and long-lasting bactericide. However, if nano-silver is used directly for sterilization, there are problems such as high price, easy aggregation, and unstable release. For many years, scientists have been trying to uniformly load nano-silver in various carriers to obtain better bactericidal effects.

Molecular sieve is a crystalline silicate or aluminosilicate with regular structure and good thermal and hydrothermal stability. At the same time, the narrow pores of molecular sieve can effectively prevent the aggregation of silver nanoparticles and control their release rate. It is a very ideal Ag fungicide slow-controlled release carrier.

At present, the use of molecular sieves to encapsulate nano silver has made some research progress. For example, some studies have successfully synthesized Ag-TiO ₂ nanotube composite material by using _a new two-step hydrothermal method. However, the scanning electron microscope results showed that there were 32 to 103nm silver nanoparticles free on the outside of the material. There are also studies to pack Ag nanoparticles into hollow ZSM-5 molecular sieve crystals by traditional impregnation method, or use ion exchange method to locate Ag clusters in the pores of molecular sieves. Although the above methods can all synthesize molecular sieve-encapsulated nano-silver fungicides, during the loading process, a part of the metal precursor is inevitably adsorbed on the outer surface or skeleton of the carrier, resulting in uneven distribution of Ag, which in turn leads to the release of Ag fungicides. If the rate is too fast, it will eventually affect the bactericidal performance.

Therefore, it is still necessary to develop a new and universal preparation method of molecular sieve-encapsulated nano-silver fungicides to improve the bactericidal activity and controllable release rate of nano-silver fungicides.

Contents of the invention

In order to overcome the deficiencies of the above-mentioned prior art, the present invention proposes a preparation method of an all-silicon molecular sieve-encapsulated nano-silver bactericide. The prepared bactericide is composed of an all-silicon molecular sieve carrier and an active component loaded on the carrier. Divided into silver nanoparticles, the nano-silver metal is evenly dispersed inside the carrier. The reaction system involved in the preparation method is simple, the reaction conditions are mild, and the obtained all-silicon molecular sieve-encapsulated nano-silver fungicide has a novel structure, high bactericidal activity and controllable release rate, and has wide application as a broad-spectrum fungicide prospect.

In order to achieve the above object, the technical solution adopted in the present invention is:

The present invention provides a kind of preparation method of all-silicon molecular sieve encapsulation nano-silver bactericide, the method comprises the following steps:

S1. After diluting the tetrapropylammonium hydroxide solution with water, add (3-mercaptopropyl)trimethoxysilane to make a mixed solution, then add silver nitrate aqueous solution to the mixed solution, and keep stirring for more than 30 minutes;

S2. Add tetraethyl silicate to the mixing system in step S1 to obtain silver-silica sol, and the silver-silica sol is aged to obtain silver-silica gel;

S3. After the silver-silica gel in step S2 is statically crystallized, it is roasted at a high temperature in an air atmosphere, and then reduced at a high temperature in a hydrogen atmosphere, and finally an all-silicon molecular sieve-encapsulated nano-silver fungicide is prepared.

Preferably, the temperature of the static crystallization is 90-125° C., and the time is 48-144 hours. Specifically, the static crystallization is static crystallization at 95° C. for 4 days.

Preferably, the temperature of the high-temperature calcination is 300-550° C., the time is 1-8 hours, and the heating rate is 0.5-5° C./min. Specifically, the temperature of the high-temperature calcination is 500° C., the time is 2 hours, and the heating rate is 0.5° C./min.

Preferably, the temperature of the high-temperature reduction is 250-500°C, the time is 2-4 hours, and the heating rate is 0.5-5°C/min. Specifically, the temperature of the high-temperature reduction is 300° C., the time is 2 hours, and the heating rate is 0.5° C./min.

Preferably, the aging temperature is 40-90° C. and the aging time is 1-2 hours. Specifically, the aging temperature is 80° C. and the aging time is 1 hour.

Preferably, in step S1, the concentration of the tetrapropylammonium hydroxide solution is 25wt% ~ 40wt%, the concentration of the silver nitrate aqueous solution is 0.2wt% ~ 0.3wt%, dilute with water to make the silver obtained in step S2- The concentration of tetrapropylammonium hydroxide in the silica sol is 9.0-10.0wt%, and the concentration of silver nitrate is 0.06-0.08wt%.

Preferably, the molar ratio of tetrapropylammonium hydroxide to tetraethyl silicate is 1:2-5.

Preferably, the molar ratio of silver nitrate to (3-mercaptopropyl)trimethoxysilane is 1:10-40.

Preferably, the molar ratio of tetrapropylammonium hydroxide to (3-mercaptopropyl)trimethoxysilane is 1:0.15-0.25.

The present invention also provides an all-silicon molecular sieve-encapsulated nano-silver bactericide prepared by the above-mentioned preparation method of an all-silicon molecular sieve-encapsulated nano-silver bactericide.

Compared with prior art, the beneficial effect of the present invention is:

The invention provides a method for preparing a nano-silver fungicide encapsulated by an all-silicon molecular sieve. The nano-silver precursor complex formed by (3-mercaptopropyl)trimethoxysilane and silver nitrate is introduced into the synthesis system of an all-silicon molecular sieve. Then the nano-silver precursor is encapsulated into the all-silicon molecular sieve through in-situ static crystallization, and finally the nano-silver fungicide encapsulated by the all-silicon molecular sieve is prepared by high-temperature roasting and hydrogen reduction. On the one hand, the coordination of (3-mercaptopropyl) trimethoxysilane and silver ions is used to protect silver ions to prevent their precipitation in the alkaline sol of synthetic molecular sieves, and to use (3-mercaptopropyl) trimethoxysilane to protect silver ions. The interaction between oxysilane and molecular sieve precursors enables silver ions to be encapsulated into molecular sieve channels during the synthesis process, which avoids the aggregation of silver ions on the outer surface of molecular sieves to the greatest extent, and contributes to the uniformity of silver ions in the molecular sieve channels. dispersion. On the other hand, the limited pore size of molecular sieves can also effectively limit the release rate of silver ions, avoid the occurrence of violent release, and achieve the purpose of slow and controlled release. It can be used as a broad-spectrum fungicide and has broad application prospects.

Description of drawings

Fig. 1 is the XRD pattern of all-silicon molecular sieve encapsulation nano-silver fungicide;

Figure 2 is a TEM image of the nano-silver fungicide encapsulated by all-silicon molecular sieves.

Detailed ways

Specific embodiments of the present invention will be further described below. It should be noted here that the descriptions of these embodiments are used to help understand the present invention, but are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not constitute a conflict with each other.

The experimental methods in the following examples, unless otherwise specified, are conventional methods, and the test materials used in the following examples, unless otherwise specified, can be purchased through conventional commercial channels.

Embodiment 1 A kind of preparation method of all-silicon molecular sieve encapsulation nano-silver fungicide (using Silicalite-1 molecular sieve as molecular sieve carrier)

(1) Take 7.32g of tetrapropylammonium hydroxide aqueous solution (TPAOH, 40wt%), add 5g of H ₂ O to dilute, then add 0.507mL of (3-mercaptopropyl)trimethoxysilane, mix well to make a mixed solution; Take 0.022g of silver nitrate (AgNO ₃ ), add 7.887g of H ₂ O to dissolve it into an aqueous solution of silver nitrate, add the obtained aqueous solution of silver nitrate dropwise into the above mixed solution, and keep stirring for 30 minutes.

(2) Add 10g of tetraethyl silicate (TEOS) dropwise to the above mixing system, mix evenly to obtain a colorless and transparent silver-silica sol, heat the obtained silver-silica sol to 80°C, stir and age for 1h, and obtain silver -Silicone gel.

(3) Put the above silver-silica gel into a polytetrafluoroethylene-lined crystallization kettle for static crystallization at 95°C for 4 days, centrifuge, wash, and dry after crystallization, and transfer the obtained sample to a tube In the furnace, heat up to 500°C for 2 hours in an air atmosphere (heating rate 0.5°C/min), cool to room temperature after roasting, and then heat up to 300°C in a hydrogen atmosphere for 2 hours (heating rate 0.5°C/min), The all-silicon molecular sieve-encapsulated nano-silver fungicide (Ag@Silicalite-1) can be obtained.

Carry out X-ray diffraction (XRD) and transmission electron microscope (TEM) analysis to the prepared all-silicon molecular sieve encapsulation nano-silver bactericide, can draw from the XRD data of Fig. 1, the self structure of Silicalite-1 molecular sieve after encapsulation has not been affected. obvious impact. From the transmission electron microscopy data in Figure 2, it can be seen that Ag nanoparticles are uniformly dispersed in the Silicalite-1 molecular sieve crystal, with a particle size of about 1-2nm.

Embodiment 2 A kind of preparation method of all-silicon molecular sieve encapsulated nano-silver fungicide

(1) Take 7.32g of tetrapropylammonium hydroxide aqueous solution (TPAOH, 40wt%), add 5g of H ₂ O to dilute, then add 0.622mL of (3-mercaptopropyl)trimethoxysilane, mix well to make a mixed solution; Take 0.027g of silver nitrate (AgNO ₃ ), add 7.887g of H ₂ O to dissolve it into an aqueous solution of silver nitrate, add the obtained aqueous solution of silver nitrate dropwise into the above mixed solution, and keep stirring for 30 minutes.

(2) Add 10g of tetraethyl silicate (TEOS) dropwise to the above mixing system, mix evenly to obtain a colorless and transparent silver-silica sol, heat the obtained silver-silica sol to 80°C, stir and age for 1h, and obtain silver -Silicone gel.

(3) Put the above silver-silica gel into a polytetrafluoroethylene-lined crystallization kettle for static crystallization at 95°C for 4 days, centrifuge, wash, and dry after crystallization, and transfer the obtained sample to a tube In the furnace, heat up to 500°C in an air atmosphere for 2 hours (heating rate: 0.5°C/min), cool to room temperature after roasting, and then heat up to 300°C in a hydrogen atmosphere for 2 hours (heating rate: 0.5°C/min) , the all-silicon molecular sieve-encapsulated nano-silver fungicide can be obtained.

The XRD and TEM analysis results are consistent with Example 1.

Embodiment 3 A kind of preparation method of all-silicon molecular sieve encapsulated nano-silver fungicide

(1) Take 7.32g of tetrapropylammonium hydroxide aqueous solution (TPAOH, 40wt%), add 5g of H ₂ O to dilute, then add 0.761mL of (3-mercaptopropyl)trimethoxysilane, mix well to make a mixed solution; Take 0.033g of silver nitrate (AgNO ₃ ), add 7.887g of H ₂ O to dissolve it into an aqueous solution of silver nitrate, add the obtained aqueous solution of silver nitrate dropwise to the above mixed solution, and keep stirring for 30 minutes.

(2) Add 10g of tetraethyl silicate (TEOS) dropwise to the above mixing system, mix evenly to obtain a colorless and transparent silver-silica sol, heat the obtained silver-silica sol to 80°C, stir and age for 1h, and obtain silver -Silicone gel.

(3) Put the above silver-silica gel into a polytetrafluoroethylene-lined crystallization kettle for static crystallization at 95°C for 4 days, centrifuge, wash, and dry after crystallization, and transfer the obtained sample to a tube In the furnace, heat up to 500°C for 2 hours in an air atmosphere (heating rate 0.5°C/min), cool to room temperature after roasting, and then heat up to 300°C in a hydrogen atmosphere for 2 hours (heating rate 0.5°C/min), The all-silicon molecular sieve-encapsulated nano-silver fungicide can be obtained.

The XRD and TEM analysis results are consistent with Example 1.

Example 4 A preparation method of all-silicon molecular sieve encapsulated nano-silver bactericide

(1) Take 7.32g of tetrapropylammonium hydroxide aqueous solution (TPAOH, 40wt%), add 5g of H ₂ O to dilute, then add 1.153mL of (3-mercaptopropyl)trimethoxysilane, mix well to make a mixed solution; Take 0.05g of silver nitrate (AgNO ₃ ), add 7.887g of H ₂ O to dissolve it into an aqueous solution of silver nitrate, add the obtained aqueous solution of silver nitrate dropwise into the above mixed solution, and keep stirring for 30 minutes.

(2) Add 10g of tetraethyl silicate (TEOS) dropwise to the above mixing system, mix evenly to obtain a colorless and transparent silver-silica sol, heat the obtained silver-silica sol to 80°C, stir and age for 1h, and obtain silver -Silicone gel.

(3) Put the above silver-silica gel into a polytetrafluoroethylene-lined crystallization kettle for static crystallization at 95°C for 4 days, centrifuge, wash, and dry after crystallization, and transfer the obtained sample to a tube In the furnace, heat up to 500°C for 2 hours in an air atmosphere (heating rate 0.5°C/min), cool to room temperature after roasting, and then heat up to 300°C in a hydrogen atmosphere for 2 hours (heating rate 0.5°C/min), The all-silicon molecular sieve-encapsulated nano-silver fungicide can be obtained.

The XRD and TEM analysis results are consistent with Example 1.

Example 5 A preparation method of all-silicon molecular sieve encapsulated nano-silver bactericide

(1) Take 7.32g of tetrapropylammonium hydroxide aqueous solution (TPAOH, 40wt%), add 5g of H ₂ O to dilute, then add 0.577mL of (3-mercaptopropyl)trimethoxysilane, mix well to make a mixed solution; Take 0.25g of silver nitrate (AgNO ₃ ), add 7.887g of H ₂ O to dissolve it into an aqueous solution of silver nitrate, add the obtained aqueous solution of silver nitrate dropwise into the above mixed solution, and keep stirring for 30 minutes.

(2) Add 10g of tetraethyl silicate (TEOS) dropwise to the above mixing system, mix evenly to obtain a colorless and transparent silver-silica sol, heat the obtained silver-silica sol to 80°C, stir and age for 1h, and obtain silver -Silicone gel.

(3) Put the above silver-silica gel into a polytetrafluoroethylene-lined crystallization kettle for static crystallization at 95°C for 4 days, centrifuge, wash, and dry after crystallization, and then transfer the obtained sample to a tube furnace In an air atmosphere, the temperature was raised to 500 ° C for 2 hours (heating rate 0.5 ° C / min), cooled to room temperature after roasting, and then heated to 300 ° C in a hydrogen atmosphere for 2 hours (heating rate 0.5 ° C / min), that is An all-silicon molecular sieve-encapsulated nano-silver fungicide can be obtained.

The XRD and TEM analysis results are consistent with Example 1.

Comparative Example 1 All-silicon molecular sieve loaded with nano-silver by impregnation method

Immerse 5g of all-silicon molecular sieve (Silicalite-1 molecular sieve) in 10mL of silver nitrate aqueous solution (0.16wt%), evaporate the water and heat up to 500°C for 2 hours in an air atmosphere (heating rate 0.5°C/min), and cool to room temperature Afterwards, the temperature was raised to 300° C. for reduction in hydrogen atmosphere for 2 hours (heating rate 0.5° C./min), and an all-silicon molecular sieve loaded with nano silver by impregnation method was obtained.

Experimental Example 1 Silver ion release rate test

Taking the all-silicon molecular sieve-encapsulated nano-silver fungicides of Examples 1 and 2 as examples, and taking the all-silicon molecular sieve samples loaded with nano-silver by impregnation method as a control, their silver ion release rates were tested.

Take respectively the all-silicon molecular sieve packaged nano-silver sample of embodiment 1 and 2 and the all-silicon molecular sieve sample (calculated by silver content, each sample contains about 0.4 mg of nano-silver) by impregnation method in a 50mL centrifuge tube, Add 20 mL of absolute ethanol and continue to shake for six days. During each sampling period, centrifuge at 5000 rpm for 10 min. Use a pipette gun to take 1 mL of the supernatant as a sample, and add 1 mL of absolute ethanol. The obtained supernatant was carried out by ICP test to measure the concentration of silver ions, and the calculated initial release rate of the all-silicon molecular sieve encapsulated nano-silver sample of Example 1 was about 3.38mg/L/d, and dropped to about 0.47mg/L after six days /d; the initial release rate of the all-silicon molecular sieve encapsulated nano-silver sample of Example 2 is about 1.61mg/L/d, and drops to about 0.225mg/L/d after six days; the all-silicon molecular sieve sample loaded with nano-silver by impregnation method The initial release rate is about 13.33mg/L/d, which drops to about 2.50mg/L/d after six days. It can be seen that the all-silicon molecular sieve-encapsulated nano-silver fungicide prepared by the method of the present invention has a controllable release rate of silver ions.

Experimental example 2 Bactericidal effect test

Weigh 0.2g all-silicon molecular sieve encapsulated nano-silver sample (taking Example 1 as an example) and the all-silicon molecular sieve sample loaded with nano-silver by impregnation method respectively in a sterilized 50mL centrifuge tube, add 20mL deionized water, and shake for 30 Two days later, the sample was centrifuged, washed to remove the silver ions adsorbed on the surface, dried and weighed 0.05g as a sample, placed in a sterilized 50mL centrifuge tube, added 5mL of PBS buffer, and shaken at 37°C for 24h to make it Fully release the Ag ions, then add 0.1mL of Escherichia coli bacteria liquid to it as the experimental group, and perform the same operation with blank PBS buffer as the control group. Place the above-mentioned samples with bacterial solution in a 37°C incubator for 2 hours, and then adopt a ten-fold dilution method to obtain a sample diluted ^10-2 times. Take 0.1mL of the diluted supernatant and spread evenly on the solid culture medium. In the base 9cm plastic culture dish, cultivate 18h at 37 ℃ again, take out and count, the result shows that the bactericidal rate of the all-silicon molecular sieve encapsulation nano-silver sample of embodiment 1 can reach more than 99%; The silicon molecular sieve sample has lost its bactericidal ability. It can be seen that the all-silicon molecular sieve-encapsulated nano-silver bactericide prepared by the method of the present invention has relatively high bactericidal activity.

The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, without departing from the principle and spirit of the present invention, various changes, modifications, substitutions and modifications to these embodiments still fall within the protection scope of the present invention.

Claims (7)

1. a kind of preparation method of all-silicon molecular sieve encapsulating nano-silver bactericide, is characterized in that, comprises the following steps: S1. After diluting the tetrapropylammonium hydroxide solution with water, add (3-mercaptopropyl)trimethoxysilane to make a mixed solution, then add silver nitrate aqueous solution to the mixed solution, and keep stirring for more than 30 minutes. The molar ratio of propylammonium hydroxide to (3-mercaptopropyl)trimethoxysilane is 1:0.15～0.25, and the molar ratio of silver nitrate to (3-mercaptopropyl)trimethoxysilane is 1:10 ~40; S2, add tetraethyl silicate to the mixing system of step S1, obtain silver-silica sol, silver-silica sol obtains silver-silica gel after aging again, described tetraethyl silicate and tetrapropyl hydroxide The molar ratio of ammonium is 2-5:1; S3. After the silver-silica gel in step S2 is statically crystallized, it is roasted at a high temperature in an air atmosphere, and then reduced at a high temperature in a hydrogen atmosphere, and finally an all-silicon molecular sieve-encapsulated nano-silver fungicide is prepared. 2. The preparation method of a nano-silver fungicide encapsulated with all-silicon molecular sieve according to claim 1, characterized in that, the static crystallization temperature is 90-125° C. and the time is 48-144 hours. 3. The preparation method of a kind of all-silicon molecular sieve-encapsulated nano-silver fungicide according to claim 1, characterized in that, the temperature of the high-temperature roasting is 300-550° C., the time is 1-8 hours, and the heating rate is 0.5 ~5°C/min. 4. The preparation method of a kind of all-silicon molecular sieve-encapsulated nano-silver fungicide according to claim 1, characterized in that, the temperature of the high-temperature reduction is 250-500° C., the time is 2-4 hours, and the heating rate is 0.5 ~5°C/min. 5 . The method for preparing a nano-silver fungicide encapsulated with all-silicon molecular sieves according to claim 1 , wherein the aging temperature is 40-90° C. and the aging time is 1-2 hours. 6 . 6. The preparation method of a kind of all-silicon molecular sieve encapsulated nano-silver bactericide according to claim 1, characterized in that, in step S1, the concentration of the tetrapropylammonium hydroxide solution is 25wt%～40wt%, so The concentration of the silver nitrate aqueous solution is 0.2wt%～0.3wt%, adding water to dilute the concentration of tetrapropylammonium hydroxide in the silver-silica sol gained in step S2 is 9.0-10.0wt%, and the concentration of silver nitrate is 0.06-0.08 wt%. 7. The all-silicon molecular sieve-encapsulated nano-silver bactericide prepared by the method for preparing the all-silicon molecular sieve-encapsulated nano-silver bactericide according to any one of claims 1-6.

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