CN113318257A

CN113318257A - Preparation method of silver nanowire loaded graphene aerogel for air purification and sterilization

Info

Publication number: CN113318257A
Application number: CN202110591652.7A
Authority: CN
Inventors: 张学骜; 闫博; 蔡加法; 郭晓晓; 程书建; 林明源
Original assignee: Xiamen University
Current assignee: Xiamen University
Priority date: 2021-05-28
Filing date: 2021-05-28
Publication date: 2021-08-31
Anticipated expiration: 2041-05-28
Also published as: CN113318257B

Abstract

A preparation method of graphene aerogel loaded by silver nanowires for air purification and sterilization relates to a sterilization material for air purification. Dissolving silver nitrate in deionized water, and mixing and stirring to obtain a uniform mixed solution A; adding ammonia water into the mixed solution A until the precipitate is completely dissolved to obtain a mixed solution B; dissolving PVP, SDS and sodium citrate in deionized water to obtain a mixed solution C; mixing the mixed solution B with the mixed solution C, and carrying out hydrothermal reaction to obtain a silver nanowire solution; stirring a part of silver nanowire solution and graphene oxide solution, adding ascorbic acid, alkyl glycoside and stearic acid, stirring until the solution foams and expands, and then placing the solution in a forced air oven for reaction; freezing, then unfreezing, and after completely unfreezing, respectively washing with deionized water and absolute ethyl alcohol; directly putting the washed sample into a freeze dryer for freeze drying; and annealing to obtain the graphene aerogel loaded by the silver nanowires for air purification and sterilization. The three-dimensional structure is stable, and has antibacterial and degerming effects.

Description

Preparation method of silver nanowire loaded graphene aerogel for air purification and sterilization

Technical Field

The invention relates to a sterilization material in the aspect of air purification, in particular to a preparation method of a graphene aerogel loaded by silver nanowires for air purification and sterilization.

Background

Air quality is closely related to the life of each person, various air quality problems exist in places such as offices and hotels, problems such as food insanitation and the like need to be prevented from being caused by excessive microorganisms in production environments such as food factories, and the air purification by sterilization in hospitals, clinics and the like plays an important role in relieving the illness state of patients, controlling the infection source and cutting off the transmission path. At present, measures such as ventilation, filtration, ultraviolet sterilization, disinfection and ozone sterilization are mainly used for preventing microbial pollution in air, and the measures can cause more or less problems.

Graphene Aerogel (GA) is used as a three-dimensional graphene material, and is generally prepared by taking Graphene Oxide (GO) as a precursor and then performing simple drying treatment. The preparation principle is that electrostatic repulsion between sheet layers of GO is weakened after the GO is subjected to gelation treatment, and the conjugation of pi-pi bonds is strengthened, so that the sheet layers of graphene recover a conjugated structure. However, since the space structure thereof has resistance, a graphite structure is not formed but is assembled into a GA having a three-dimensional structure, and thus the GA retains a high specific surface area of graphene. In addition, because the constituent units of the graphene nano-sheets are graphene nano-sheets, the GA has the characteristics of high porosity (80-99.8%), modifiability, low density, high elasticity, high specific surface area and the like, and the characteristics of the graphene aerogel can be applied to various adsorption aspects, such as oil and fat adsorption, and air purification through active or passive adsorption.

Silver is used as a material which is originally used by the ancient people for antisepsis and sterilization, and various silver-doped composite materials are prepared to be used for various aspects of filtration, sterilization and the like till the modern time. The silver nanowires have small size, large specific surface area and excellent antibacterial performance, and the action mode of the silver nanowires is to reduce the permeability of cell membranes by releasing anions so that cytoplasm is lost, and further the replication of DNA is influenced to achieve the effects of sterilization and disinfection.

Patent CN106622046A for preparing Ag/CeO with double functions of photocatalytic degradation of dye and sterilization₂Graphene aerogel materials. A novel sol-gel method is developed by an ACS Nano 2018,12, 11407-contained 11416 university Quliang body topic group of Beijing Physician university, and large-area graphene aerogel with complete structure is prepared by using microbubbles as a template and carrying out a series of reactions, wherein the aerogel has superelasticity of up to 99% compressive strain and very low density (2.8 mg/cm)³)。

However, the framework of the graphene aerogel in the literature is not stable enough, and the damage of the three-dimensional structure of the GA may occur in the drying process or the repeated utilization process, so that how to make the three-dimensional structure of the GA more stable, but the sterilization effect is achieved, has a very important meaning.

Disclosure of Invention

The invention aims to solve the problems that a graphene aerogel framework is unstable, a GA three-dimensional structure is easy to damage and the like in the preparation of the material, and provides a preparation method of the graphene aerogel loaded with silver nanowires for air purification and sterilization, which has the advantages of simple process, low cost, more stable three-dimensional structure, antibacterial and sterilization effects and can meet various shape requirements by meeting the requirements of different containers and changing the shape of the graphene aerogel.

The invention comprises the following steps:

1) dissolving silver nitrate in deionized water, and mixing and stirring to obtain a uniform mixed solution A;

2) adding ammonia water into the mixed solution A obtained in the step 1) until the precipitate is completely dissolved to obtain a mixed solution B;

3) dissolving polyvinylpyrrolidone (PVP), Sodium Dodecyl Sulfate (SDS) and sodium citrate in deionized water to obtain a mixed solution C;

4) mixing the mixed solution B obtained in the step 2) with the mixed solution C obtained in the step 3), and placing the mixture in a reaction kettle for hydrothermal reaction to obtain a silver nanowire solution;

5) stirring a part of the silver nanowire solution obtained in the step 4) with a graphene oxide solution, adding ascorbic acid, alkyl glycoside and stearic acid, stirring until the solution foams and expands, and placing the solution in a blast oven for reaction;

6) freezing the sample obtained in the step 5), then unfreezing, and after completely unfreezing, respectively washing with deionized water and absolute ethyl alcohol;

7) directly putting the sample washed in the step 6) into a freeze dryer for freeze drying; and then annealing treatment is carried out to obtain the graphene aerogel loaded by the silver nanowires for air purification and sterilization.

In the step 1), the ratio of the silver nitrate to the deionized water can be (1-3): 2000, wherein the silver nitrate is calculated by mass (g), and the deionized water is calculated by volume (ml); the stirring time can be 0.3 h-1 h.

In the step 3), the mass ratio of the polyvinylpyrrolidone (PVP), the Sodium Dodecyl Sulfate (SDS) and the sodium citrate is (2-2.5) to 2:1, and the volume of deionized water is 200-400 ml.

In the step 4), the temperature of the hydrothermal reaction can be 90-160 ℃, and the time of the hydrothermal reaction can be 6-12 h.

In the step 5), the stirring time can be 0.5-1 h, the concentration of the graphene oxide solution is 8-32 mg/mL, and the sheet diameter of the graphene oxide can be 10-50 μm; the mass ratio of the ascorbic acid to the graphene oxide is (1.5-2.5): 1, and the ratio of the alkyl glycoside to the graphene oxide is (1-2): 1, wherein the volume (ml) of the alkyl glycoside is calculated, and the mass (g) of the graphene oxide is calculated; the mass of the stearic acid can be 0.1-0.5% of that of the graphene oxide; the rotating speed of the secondary stirring can be 900-2000 r; the solution can be foamed and expanded to be 1.5-2.5 times of the original volume; the reaction in the blast oven can be carried out for 11-14 h at 75-80 ℃.

In the step 6), the freezing temperature can be-10 to-20 ℃, and the freezing time can be 4 to 12 hours; the flushing can be performed for 2-5 times.

In step 7), the freeze-drying time may be 6 h; the freeze drying time can be 24-36 h; the annealing temperature can be 200-220 ℃, and the annealing time can be 2-6 h.

According to the invention, graphene oxide and silver nitrate are mixed to prepare the graphene aerogel, and the silver nanowires are loaded on the graphene aerogel, so that the three-dimensional structure of the graphene aerogel is more stable, and the graphene aerogel has antibacterial and antibacterial effects. And can also change the shape of graphite alkene aerogel through placing mixed liquid in the container that holds of difference to satisfy different user demands. In the process of preparing the graphene aerogel, the environment-friendly foaming agent alkyl glycoside is utilized, and the foam stabilizer stearic acid is added, so that the bubbles become stable during heat preservation, the original sizes of the bubbles can be maintained, and the bubbles can stably exist as a template; then washing with ultrapure water and absolute ethyl alcohol can wash away the redundant stearic acid and ascorbic acid; combining a phase diagram of water, directly placing the silver nanowire/graphene aerogel in a freeze dryer by utilizing the characteristic that water can be frozen under low pressure, wherein the pore size of the freeze-dried graphene aerogel is smaller than that of the graphene aerogel dried at normal temperature and normal pressure, and the corresponding specific surface area is also much larger; the final annealing treatment can decompose the residual alkyl glycoside therein, and only the graphene aerogel and the silver nanowires loaded thereon are left. In addition, the invention has the advantages of lower cost, capability of meeting different use requirements, mass production, good repeatability and the like, and has higher economic value. The silver nanowire/graphene aerogel has the functions of sterilization and disinfection, and the obtained graphene aerogel material loaded with the silver nanowires for air purification and sterilization can be used in various places without causing secondary pollution to the environment.

Drawings

Figure 1 elastic modulus of silver nanowire/graphene aerogel prepared in example 2.

Figure 2 elastic modulus of silver nanowire/graphene aerogel prepared in example 3.

Fig. 3 is a colony culture diagram of the silver nanowire/graphene aerogel prepared in example 2.

Detailed Description

According to the method, graphene oxide is used as a raw material, the prepared silver nanowire precursor is mixed with a graphene oxide solution, a bubble-ice template method is used, a foaming agent alkyl glycoside, a foaming agent stearic acid and a reducing agent ascorbic acid are added, and the GA is prepared through the gelation of GO. The following examples will further illustrate the present invention with reference to the accompanying drawings.

Example 1:

in this embodiment, a silver nanowire solution is prepared in a solution as a precursor, and a bubble-ice template is used to prepare a silver nanowire/graphene aerogel, wherein the specific preparation method is as follows:

(1) 0.1g of silver nitrate was weighed and dissolved in 200mL of deionized water and stirred for 30 min.

(2) And dropwise adding ammonia water into the silver nitrate solution until the precipitate of the silver nitrate solution is completely dissolved.

(3) An additional 0.6g of PVP, 0.6g SDS and 0.3g sodium citrate were weighed into 300mL deionized water and stirred for 10 min.

(4) And (4) placing the mixed solution obtained in the step (4) in a reaction kettle for hydrothermal reaction at the reaction temperature of 90 ℃ for 6 hours, and cooling to room temperature to obtain the silver nanowire solution.

(5) And (3) taking 100mL of the obtained silver nanowire solution and 100mL of the graphene oxide solution with the concentration of 32mg/mL, mixing the two solutions and stirring for 30 min.

(6) 4.8g of ascorbic acid, 3.2mL of alkylglycoside, and 0.0032g of stearic acid were added to the mixed solution obtained in step (5).

(7) And (4) stirring the mixed solution obtained in the step (6) at a rotating speed of about 900-2000 revolutions until the volume expansion of the solution is 2.5 times of the volume of the original solution.

(8) And (4) placing the solution foamed in the step (7) in a forced air oven for reaction at the reaction temperature of 75 ℃ for 11 h.

(9) And (5) freezing the sample obtained in the step (8), wherein the freezing temperature is approximately-15 ℃, and the freezing time is 6 h.

(10) And (4) unfreezing the frozen sample obtained in the step (9), after the sample is completely unfrozen, washing the sample twice with deionized water, and then washing the sample twice with absolute ethyl alcohol.

(11) And (4) placing the sample washed in the step (10) in a freeze dryer for freeze drying, wherein the freeze drying time is about 36 hours.

(12) And (4) annealing the sample in the step (11), wherein the annealing temperature is 220 ℃, the annealing time is 6h, and the atmosphere condition is air.

Example 2:

(1) 0.3g of silver nitrate was weighed and dissolved in 200mL of deionized water and stirred for 60 min.

(3) An additional 0.75g PVP, 0.6g SDS and 0.3g sodium citrate were weighed into 300mL deionized water and stirred for 10 min.

(4) And (4) placing the mixed solution obtained in the step (3) in a reaction kettle for hydrothermal reaction at the temperature of 160 ℃ for 3 hours, and cooling to room temperature to obtain the silver nanowire solution.

(5) And (3) taking 50mL of the obtained silver nanowire solution and 50mL of the graphene oxide solution with the concentration of 8mg/mL, mixing the two solutions and stirring for 60 min.

(6) 1g of ascorbic acid, 0.8mL of alkylglycoside, and 0.002g of stearic acid were added to the mixed solution obtained in step (5).

(7) And (4) stirring the mixed solution obtained in the step (6) at the rotating speed of about 1500 revolutions until the volume of the solution expands to 1.5 times of the volume of the original solution.

(8) And (4) placing the solution foamed in the step (7) in a forced air oven for reaction at the reaction temperature of 80 ℃ for 12 h.

(9) And (4) freezing the sample obtained in the step (8), wherein the freezing temperature is approximately-20 ℃, and the freezing time is 12 h.

(11) And (4) placing the sample washed in the step (10) in a freeze dryer for freeze drying, wherein the freeze drying time is about 24 hours.

(12) And (4) annealing the sample in the step (11), wherein the annealing temperature is 200 ℃, the annealing time is 2 hours, and the atmosphere condition is air.

Example 3:

(1) 0.2g of silver nitrate was weighed and dissolved in 200mL of deionized water and stirred for 60 min.

(3) An additional 0.7g of PVP, 0.6g SDS and 0.3g sodium citrate were weighed into 300mL deionized water and stirred for 10 min.

(4) And (4) placing the mixed solution obtained in the step (3) in a reaction kettle for hydrothermal reaction at the temperature of 160 ℃ for 12 hours, and cooling to room temperature to obtain the silver nanowire solution.

(5) And (3) taking 50mL of the obtained silver nanowire solution and 50mL of the graphene oxide solution with the concentration of 20mg/mL, mixing the two solutions and stirring for 60 min.

(6) 2g of ascorbic acid, 1.66mL of an alkylglycoside, and 0.003g of stearic acid were added to the mixed solution obtained in step (5).

(7) And (4) stirring the mixed solution obtained in the step (6) at a rotating speed of about 900-1500 revolutions until the volume expansion of the solution is 2 times of that of the original solution.

(9) And (4) freezing the sample obtained in the step (8), wherein the freezing temperature is approximately-18 ℃, and the freezing time is 6 h.

(12) And (4) annealing the sample in the step (11), wherein the annealing temperature is 200 ℃, the annealing time is 4h, and the atmosphere condition is air.

Fig. 1 and 2 show a compressive stress strain diagram of the silver nanowire/graphene aerogel prepared in embodiments 1 and 2, and the elastic modulus calculated according to the compressive stress strain diagram is 0.00315MPa and 0.01084MPa, respectively, so that it can be seen that the silver nanowire/graphene aerogel prepared in embodiments 1 and 2 has a very low elastic modulus, the loading line and the unloading line are very close, the elastic hysteresis loop is very small, and the doping of the silver nanowire plays a certain supporting role on the three-dimensional structure of the graphene aerogel, thereby showing very good elasticity.

Fig. 3 shows a 2h colony culture diagram of the silver nanowire/graphene aerogel composite material prepared in example 3, and it can be seen from fig. 3 that no colony exists in a local area between the graphene aerogel and the round wire, which indicates that the prepared silver nanowire/graphene aerogel has bactericidal and bactericidal effects.

The silver nanowire/graphene aerogel is prepared by mixing a silver nanowire solution and a graphene oxide solution by adopting a sol-gel method and taking bubbles and ice as templates and adding a foaming agent, a foam stabilizer and a reducing agent. According to the invention, the silver nanowires are innovatively doped into the graphene aerogel, so that on one hand, the addition of the silver nanowires can enable the three-dimensional structure of the graphene aerogel to be more stable, and thus the graphene aerogel has a very low elastic modulus; on the other hand, due to the addition of silver, the graphene aerogel has the sterilization and antibacterial performance. The silver nanowire/graphene aerogel has the advantages of good elasticity, adjustable shape, antibacterial and bactericidal effects, strong experimental repeatability and the like, so that the silver nanowire/graphene aerogel has great competitiveness and high commercial value in the existing adsorption and purification materials.

Claims

1. The preparation method of the graphene aerogel loaded with the silver nanowires for air purification and sterilization is characterized by comprising the following steps:

3) dissolving polyvinylpyrrolidone, sodium dodecyl sulfate and sodium citrate in deionized water to obtain a mixed solution C;

5) stirring a part of the silver nanowire solution obtained in the step 4) with a graphene oxide solution, adding ascorbic acid, alkyl glycoside and stearic acid, stirring again until the solution foams and expands, and placing the solution in a blast oven for reaction;

2. The preparation method of the silver nanowire-loaded graphene aerogel for air purification and sterilization according to claim 1, wherein in the step 1), the ratio of silver nitrate to deionized water is (1-3): 2000, wherein the silver nitrate is calculated by mass (g), and the deionized water is calculated by volume (ml); the stirring time can be 0.3 h-1 h.

3. The preparation method of the silver nanowire-loaded graphene aerogel for air purification and sterilization according to claim 1, wherein in the step 3), the mass ratio of the polyvinylpyrrolidone to the sodium dodecyl sulfate to the sodium citrate is (2-2.5): 2:1, and the deionized volume is 200-400 ml.

4. The method for preparing the silver nanowire-loaded graphene aerogel for air purification and sterilization according to claim 1, wherein in the step 4), the temperature of the hydrothermal reaction is 90-160 ℃, and the time of the hydrothermal reaction is 6-12 h.

5. The method for preparing the silver nanowire-loaded graphene aerogel for air purification and sterilization according to claim 1, wherein in the step 5), the stirring time is 0.5-1 h, the concentration of the graphene oxide solution is 8-32 mg/mL, and the sheet diameter of the graphene oxide is 10-50 μm.

6. The method for preparing the silver nanowire-loaded graphene aerogel for air purification and sterilization according to claim 1, wherein in the step 5), the mass ratio of the ascorbic acid to the graphene oxide is (1.5-2.5): 1, and the ratio of the alkyl glycoside to the graphene oxide is (1-2): 1, wherein the alkyl glycoside is calculated by volume (ml) and the graphene oxide is calculated by mass (g).

7. The method for preparing the silver nanowire-loaded graphene aerogel for air purification and sterilization according to claim 1, wherein in the step 5), the mass of the stearic acid is 0.1-0.5% of the mass of the graphene oxide; the rotating speed of the secondary stirring can be 900-2000 r.

8. The method for preparing the silver nanowire-loaded graphene aerogel for air purification and sterilization according to claim 1, wherein in the step 5), the solution expands to 1.5 to 2.5 times of the original volume by foaming; the reaction in the blast oven is carried out for 11-14 h at 75-80 ℃.

9. The preparation method of the silver nanowire-loaded graphene aerogel for air purification and sterilization according to claim 1, wherein in the step 6), the freezing temperature is-10 to-20 ℃, and the freezing time is 4 to 12 hours; the flushing can be performed for 2-5 times.

10. The method for preparing the silver nanowire-loaded graphene aerogel for air purification and sterilization according to claim 1, wherein in the step 7), the freeze-drying time is 6 hours and the freeze-drying time is 24-36 hours; the annealing temperature is 200-220 ℃, and the annealing time is 2-6 h.