CN112841295A - Ag NWs-TiO2NS modified chitosan composite bactericidal coating film, preparation method and application thereof - Google Patents
Ag NWs-TiO2NS modified chitosan composite bactericidal coating film, preparation method and application thereof Download PDFInfo
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- 229910001961 silver nitrate Inorganic materials 0.000 claims description 6
- 239000000725 suspension Substances 0.000 claims description 6
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- 125000000218 acetic acid group Chemical class C(C)(=O)* 0.000 claims description 2
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- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
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- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
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Images
Classifications
-
- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23B—PRESERVING, e.g. BY CANNING, MEAT, FISH, EGGS, FRUIT, VEGETABLES, EDIBLE SEEDS; CHEMICAL RIPENING OF FRUIT OR VEGETABLES; THE PRESERVED, RIPENED, OR CANNED PRODUCTS
- A23B5/00—Preservation of eggs or egg products
- A23B5/06—Coating eggs with a protective layer; Compositions or apparatus therefor
-
- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23V—INDEXING SCHEME RELATING TO FOODS, FOODSTUFFS OR NON-ALCOHOLIC BEVERAGES AND LACTIC OR PROPIONIC ACID BACTERIA USED IN FOODSTUFFS OR FOOD PREPARATION
- A23V2002/00—Food compositions, function of food ingredients or processes for food or foodstuffs
Abstract
The Ag NWs-TiO of the invention2 The NS modified chitosan composite bactericidal coating is characterized in that: first of all, TiO is prepared2Nanosheet (TiO)2 NS); secondly, depositing Ag nano-wires (Ag NWs) on the TiO by a reduction method2Nano-sheets; finally, a series of Ag NWs-TiO with different concentrations were prepared by adding a certain amount of Chitosan (CS)2 And (3) performing NS/chitosan composite coating. The Ag NWs-TiO of the invention2 The NS modified chitosan composite bactericidal coating adopts a technology and a method which are green, safe, simple and convenient to operate and efficient to prolong the shelf life of eggs, and has great significance for promoting the further development of the fresh egg market in China.
Description
Technical Field
The invention relates to the field of preservation by a coating technology, in particular to Ag NWs-TiO2 NS modified chitosan composite bactericidal coating material and a preparation method thereof.
Background
Since 1985, the total egg yield of China gradually surpasses the United states and leaps the first in the world. According to the statistics of Food and Agricultural Organization (FAO) of the United nations, the egg yield of China in 2019 reaches 3500 million tons, which is about 4.4 times of that of the United states, 6.5 times of that of India and accounts for about 40 percent of the total world production. The egg occupation of the average number of people in China is about 20.03 kg/person, which is higher than the average level in the world and is in the front of the world. However, the overall development level of the egg industry in China still has a large gap compared with advanced countries in the world. The consumption of residents in China is mainly fresh eggs, so the total consumption of the fresh eggs accounts for 90 percent of the total production of the eggs in China. However, the shelf life of fresh eggs is short at normal temperature, and the quality of the eggs is reduced under the influence of the external environment; the egg has a brittleness value of about 60g, belongs to fragile products, and has high breakage rate in the transportation process; the packaging of eggs is mainly a pulp egg tray which is easy to damage. The development of the fresh egg market in China is greatly influenced, the international market cannot be smoothly opened, and the export of the fresh eggs in China is influenced. Therefore, the method and the device have great significance for promoting the further development of the fresh egg market in China by researching green, safe, simple and efficient technology and method for prolonging the shelf life of eggs.
At present, the chitosan coating is researched more in egg preservation, for example, the molecular weight, the type and the like of chitosan are optimized, and the preservation effect of chitosan can be improved by compounding the chitosan with other substances. However, chitosan is a hydrophilic polymer, has poor water vapor barrier properties, is prone to swelling due to moisture absorption, and has an unstable structure in a high-humidity environment. Therefore, in general, the fresh-keeping effect of the chitosan and the composite coating thereof is not long enough, and the effect of prolonging the shelf life of eggs is limited. And the current research focuses on monitoring the quality change of the coated eggs, and few researches observe the coating structure of chitosan. The main mechanism of the coating preservation is to reduce CO in the egg content by utilizing the barrier property of the coating2And loss of moisture, reducing its respiration rate and preventing invasion of microorganisms, so the structure and thickness of the coating film and its stability during storage are closely related to its freshness-retaining effect.
Therefore, the purpose of the patent is to monitor the structure of the chitosan coating and the change of the structure in the storage process while observing the influence of the coating layer number, the coating liquid concentration, the compounding with other polymers or the addition of nanoparticles on the preservation effect of the chitosan coating, and the like, so as to discuss the influence mechanism of the chitosan coating on the preservation effect of eggs from the aspect of the influence of different coating modes on the chitosan coating structure. And further improving the fresh-keeping effect of the coated eggs and preparing the efficient egg sterilizing and fresh-keeping material.
Disclosure of Invention
In order to achieve the above object, the present invention provides Ag NWs-TiO2 NS modified chitosan composite bactericidal coating material. The invention aims to provide a preparation method of a composite chitosan coating film for egg preservation. The composite chitosan coating obtained by the preparation method can clean and sterilize, prevent invasion of bacteria and oxygen, prevent loss of moisture and CO2 in eggs, keep the pH value of protein acidic, inhibit respiration in the eggs, prevent growth and reproduction of aerobic bacteria, delay water sampling of egg white, inhibit yolk from yellowing and prolong the shelf life of fresh eggs.
Preferably, the eggs include chicken eggs, duck eggs, goose eggs, pigeon eggs, pheasant eggs or quail eggs.
The Ag NWs-TiO of the invention2 The NS modified chitosan composite bactericidal coating is characterized in that: first of all, TiO is prepared2Nanosheet (TiO)2 NS); secondly, depositing Ag nano-wires (Ag NWs) on the TiO by a reduction method2Nano-sheets; finally, a series of Ag NWs-TiO with different concentrations were prepared by adding a certain amount of Chitosan (CS)2And (3) performing NS/chitosan composite coating.
The above Ag NWs-TiO2 The preparation method of the NS modified chitosan composite bactericidal coating comprises the following specific steps:
step 1: TiO22Nanosheet (TiO)2 NS) preparation
(a) Mixing tetrabutyl titanate and 30 mL hydrochloric acid with different concentrations, and magnetically stirring for 10-40 min;
(b) adding 0.1-0.6 g ammonium hexafluorotitanate into the solution, and stirring for 30-50 min;
(c) transferring the solution into a polytetrafluoroethylene lining;
(d) placing the reaction kettle in an oven, keeping the reaction kettle at 160 ℃ for 12 hours, and taking out a sample when the temperature is reduced to room temperature;
(e) repeatedly cleaning with clear water, and oven drying in oven at 80 deg.C to obtain TiO2Nanosheets.
Step 2: preparation of Ag nanowires (Ag NWs)
(a) Accurately weighing polyvinylpyrrolidone (PVP, with different molecular weights) and silver nitrate (AgNO)3) And sequentially adding the mixture into a flask;
(b) adding 80mL of glycol, and stirring gently for 5-25 min;
(c) then heating the solution at 180 ℃ for 6 hours, and cooling the solution to room temperature in a glass dryer;
(d) finally, the resulting product was washed several times with acetone and ethanol and then stored in ethanol until use.
And step 3: ag NWs-TiO2Preparation of NS composite bactericidal coating
TiO prepared by the previous step2Firstly, immersing the nanosheets into the ethanol solution of Ag NWs with a certain concentration obtained in the step 2, stirring at room temperature for reacting for 6 hours to obtain Ag NWs-TiO2NS composite bactericidal paint.
And 4, step 4: ag NWs-TiO2Preparation of NS/Chitosan (CS) composite bactericidal coating film
(a) Weighing a certain amount of chitosan, adding the chitosan into 0.5-12.6% acetic acid solution, uniformly stirring, and preparing pure chitosan coating solution with the concentration of 0.1-6.3% (w/v);
(b) then adding a certain amount of Ag NWs and TiO mixed in the step 32NS suspension, Ag NWs and TiO in coating liquid2 The mass fraction of NS is 0.5-25.0% of chitosan;
(c) stirring for 24 hours to prepare Ag NWs-TiO2 NS modified chitosan composite bactericidal coating.
In a preferred embodiment, the concentration of the hydrochloric acid solution is 1.2, 2.4, 3.6, 4.0, 4.8, 5.2, 5.6, 6.6, 7.6, 9.1, 10.6, 12.6, 15.0, 20.0 mol/L.
In a preferred embodiment, the concentration of the aqueous solution of butyl titanate varies from 0.02 to 0.6 mol/mL.
In a preferred embodiment, the AgNO is3The solution concentrations were 0.2, 0.4, 0.6 and 0.8 m/L.
In a preferred embodiment, the polyvinylpyrrolidone has a molecular weight of 8000-.
In the invention, the mass volume concentration of the chitosan solution is preferably 0.1-6.3%, more preferably 0.2-0.8%, and even more preferably 0.4-0.6%;
in a preferred embodiment, the solvent of the chitosan solution is preferably acetic acid;
in a preferred embodiment, the acetic acid is preferably provided in the form of an acetic acid solution, and the volume concentration of the acetic acid solution is preferably 0.5 to 12.6%, more preferably 1.2 to 5.6%, and still more preferably 2.1 to 3.2%.
The chitosan can be fully dissolved by dissolving the chitosan in the acetic acid solution, so that the chitosan is favorably coated on the surface of eggs, and secondly, the acetic acid is used as the solvent for dissolving the chitosan, so that when eggs are immersed in the chitosan solution, the acetic acid solution and calcium carbonate on the surface of the eggshell generate acid-base neutralization reaction, tiny cracks on the surface of the eggshell are filled, and the eggshell structure is more compact. The chitosan is physically adsorbed and cannot react with the surface of the eggshell.
On the basis of the technical scheme, the invention can be further improved as follows. Further, the egg preservation method comprises the following steps: and (3) coating the composite coating liquid for preserving the eggs on the surfaces of the eggs by adopting a coating method, and air-drying or drying to obtain the eggs with the bactericidal coatings.
The invention has the beneficial effects that:
the Ag NWs-TiO of the invention2Compared with the prior art, the NS modified chitosan composite bactericidal coating has the following main beneficial effects:
1. the preparation method of the composite chitosan coating film for egg preservation comprises the steps of preparing silver nanowires (Ag NWs) and titanium dioxide nanosheets (TiO) by self2 NS) and then compounded with Chitosan (CS), thereby greatly improving the antibacterial property and prolonging the freshness preservation of poultry eggsTime. Coating with pure chitosan, and keeping the eggs fresh for 18d-22 d; the composite chitosan coating film for keeping poultry eggs fresh has the preservation time of 60-65 days for poultry eggs, and can prolong 42-47 days compared with a simple chitosan coating film. 2. The Ag NWs-TiO prepared by the preparation method of the invention2 The NS modified chitosan composite bactericidal coating can clean and sterilize, prevent the invasion of bacteria and oxygen, prevent the loss of moisture and CO2 in eggs, keep the pH value of protein acidic, inhibit the respiration in eggs, prevent the growth and reproduction of aerobic bacteria (such as escherichia coli, staphylococcus aureus and candida albicans), delay the watery transformation of egg white, inhibit yolk from yellowing, and prolong the shelf life of fresh eggs.
3. The invention relates to Ag NWs-TiO for preserving eggs2 The preparation method of the NS modified chitosan composite bactericidal coating has the advantages of easy operation, low cost, short preparation period, good repeatability, wide market prospect and suitability for large-scale popularization and application.
Drawings
FIG. 1 shows Ag NWs-TiO prepared by the present invention2 SEM images of NS composite nanomaterials.
FIG. 2 shows Ag NWs-TiO prepared according to the present invention2 XRD patterns of NS composite nanomaterials.
Detailed description of the invention
The invention is further illustrated by the following examples
Example 1
Step 1: TiO22Nanosheet (TiO)2 NS) preparation
(a) Mixing tetrabutyl titanate with the concentration of 0.02 mol/mL and hydrochloric acid with the concentration of 30 mL being 1.2-4.8mol/L, and magnetically stirring for 10-40 min;
(b) 0.1 g of ammonium hexafluorotitanate is added into the solution and stirred for 30-50 min;
(c) transferring the solution into a polytetrafluoroethylene lining;
(d) placing the reaction kettle in an oven, keeping the reaction kettle at 160 ℃ for 12 hours, and taking out a sample when the temperature is reduced to room temperature;
(e) repeatedly cleaning with clear water, and oven drying in oven at 80 deg.C to obtain TiO2Nanosheets.
Step 2: preparation of Ag nanowires (Ag NWs)
(a) 0.2g of polyvinylpyrrolidone (PVP, molecular weight: 24000) and 0.2 m/L of silver nitrate (AgNO) were weighed accurately3) And sequentially adding the mixture into a flask;
(b) adding 80mL of glycol, and stirring gently for 5-25 min;
(c) then heating the solution at 180 ℃ for 6 hours, and cooling the solution to room temperature in a glass dryer;
(d) finally, the resulting product was washed several times with acetone and ethanol and then stored in ethanol until use.
And step 3: ag NWs-TiO2Preparation of NS composite bactericidal coating
TiO prepared by the previous step2Firstly, immersing the nanosheets into the ethanol solution of Ag NWs with a certain concentration obtained in the step 2, stirring at room temperature for reacting for 6 hours to obtain Ag NWs-TiO2NS composite bactericidal paint.
And 4, step 4: ag NWs-TiO2 Preparation of NS/Chitosan (CS) composite bactericidal coating film
(a) Weighing a certain amount of chitosan, adding the chitosan into 0.5-12.6% acetic acid solution, uniformly stirring, and preparing pure chitosan coating solution with the concentration of 0.1-6.3% (w/v);
(b) then adding a certain amount of Ag NWs and TiO mixed in the step 32 NS suspension, Ag NWs and TiO in coating liquid2 The mass fraction of NS is 0.5-25.0% of chitosan;
(c) stirring for 24 hours to prepare Ag NWs-TiO2 NS modified chitosan composite bactericidal coating.
Example 2
Step 1: TiO22Nanosheet (TiO)2 NS) preparation
(a) Mixing tetrabutyl titanate with the concentration of 0.04 mol/mL and hydrochloric acid with the concentration of 30 mL of 4.8-9.1 mol/L, and magnetically stirring for 10-40 min;
(b) 0.2g of ammonium hexafluorotitanate is added into the solution and stirred for 30-50 min;
(c) transferring the solution into a polytetrafluoroethylene lining;
(d) placing the reaction kettle in an oven, keeping the reaction kettle at 160 ℃ for 12 hours, and taking out a sample when the temperature is reduced to room temperature;
(e) repeatedly cleaning with clear water, and oven drying in oven at 80 deg.C to obtain TiO2Nanosheets.
Step 2: preparation of Ag nanowires (Ag NWs)
(a) 0.2g of polyvinylpyrrolidone (PVP, molecular weight: 58000) and 0.4 m/L of silver nitrate (AgNO) were weighed out accurately3) And sequentially adding the mixture into a flask;
(b) adding 80mL of glycol, and stirring gently for 5-25 min;
(c) then heating the solution at 180 ℃ for 6 hours, and cooling the solution to room temperature in a glass dryer;
(d) finally, the resulting product was washed several times with acetone and ethanol and then stored in ethanol until use.
And step 3: ag NWs-TiO2Preparation of NS composite bactericidal coating
TiO prepared by the previous step2Firstly, immersing the nanosheets into the ethanol solution of Ag NWs with a certain concentration obtained in the step 2, stirring at room temperature for reacting for 6 hours to obtain Ag NWs-TiO2NS composite bactericidal paint.
And 4, step 4: ag NWs-TiO2 Preparation of NS/Chitosan (CS) composite bactericidal coating film
(a) Weighing a certain amount of chitosan, adding the chitosan into 0.5-12.6% acetic acid solution, uniformly stirring, and preparing pure chitosan coating solution with the concentration of 0.1-6.3% (w/v);
(b) then adding a certain amount of Ag NWs and TiO mixed in the step 32 NS suspension, Ag NWs and TiO in coating liquid2 The mass fraction of NS is 0.5-25.0% of chitosan;
(c) stirring for 24 hours to prepare Ag NWs-TiO2 NS modified chitosan composite bactericidal coating.
Example 3
Step 1: TiO22Nanosheet (TiO)2 NS) preparation
(a) Mixing tetrabutyl titanate with the concentration of 0.06 mol/mL and hydrochloric acid with the concentration of 30 mL of 9.1-15.0 mol/L, and magnetically stirring for 10-40 min;
(b) 0.3 g of ammonium hexafluorotitanate is added into the solution and stirred for 30-50 min;
(c) transferring the solution into a polytetrafluoroethylene lining;
(d) placing the reaction kettle in an oven, keeping the reaction kettle at 160 ℃ for 12 hours, and taking out a sample when the temperature is reduced to room temperature;
(e) repeatedly cleaning with clear water, and oven drying in oven at 80 deg.C to obtain TiO2Nanosheets.
Step 2: preparation of Ag nanowires (Ag NWs)
(a) 0.2g of polyvinylpyrrolidone (PVP, molecular weight: 40000) and 0.6 m/L of silver nitrate (AgNO) were weighed accurately3) And sequentially adding the mixture into a flask;
(b) adding 80mL of glycol, and stirring gently for 5-25 min;
(c) then heating the solution at 180 ℃ for 6 hours, and cooling the solution to room temperature in a glass dryer;
(d) finally, the resulting product was washed several times with acetone and ethanol and then stored in ethanol until use.
And step 3: ag NWs-TiO2Preparation of NS composite bactericidal coating
TiO prepared by the previous step2Firstly, immersing the nanosheets into the ethanol solution of Ag NWs with a certain concentration obtained in the step 2, stirring at room temperature for reacting for 6 hours to obtain Ag NWs-TiO2NS composite bactericidal paint.
And 4, step 4: ag NWs-TiO2 Preparation of NS/Chitosan (CS) composite bactericidal coating film
(a) Weighing a certain amount of chitosan, adding the chitosan into 0.5-12.6% acetic acid solution, uniformly stirring, and preparing pure chitosan coating solution with the concentration of 0.1-6.3% (w/v);
(b) then adding a certain amount of Ag NWs and TiO mixed in the step 32 NS suspension, Ag NWs and TiO in coating liquid2 The mass fraction of NS is 0.5-25.0% of chitosan;
(c) stirring for 24 hours to prepare Ag NWs-TiO2 NS modified chitosan composite bactericidal coating.
Example 4
Step 1: TiO22Nanosheet (TiO)2 NS) preparation
(a) Mixing tetrabutyl titanate with the concentration of 0.05 mol/mL and hydrochloric acid with the concentration of 30 mL and the concentration of 15.0-20.0 mol/L, and magnetically stirring for 10-40 min;
(b) 0.25 g of ammonium hexafluorotitanate is added into the solution and stirred for 30-50 min;
(c) transferring the solution into a polytetrafluoroethylene lining;
(d) placing the reaction kettle in an oven, keeping the reaction kettle at 160 ℃ for 12 hours, and taking out a sample when the temperature is reduced to room temperature;
(e) repeatedly cleaning with clear water, and oven drying in oven at 80 deg.C to obtain TiO2Nanosheets.
Step 2: preparation of Ag nanowires (Ag NWs)
(a) Accurately weighing 0.2g polyvinylpyrrolidone (PVP, molecular weight: 1300000) and 0.8 m/L silver nitrate (AgNO)3) And sequentially adding the mixture into a flask;
(b) adding 80mL of glycol, and stirring gently for 5-25 min;
(c) then heating the solution at 180 ℃ for 6 hours, and cooling the solution to room temperature in a glass dryer;
(d) finally, the resulting product was washed several times with acetone and ethanol and then stored in ethanol until use.
And step 3: ag NWs-TiO2Preparation of NS composite bactericidal coating
TiO prepared by the previous step2Firstly, immersing the nanosheets into the ethanol solution of Ag NWs with a certain concentration obtained in the step 2, stirring at room temperature for reacting for 6 hours to obtain Ag NWs-TiO2NS composite bactericidal paint.
And 4, step 4: ag NWs-TiO2 Preparation of NS/Chitosan (CS) composite bactericidal coating film
(a) Weighing a certain amount of chitosan, adding the chitosan into 0.5-12.6% acetic acid solution, uniformly stirring, and preparing pure chitosan coating solution with the concentration of 0.1-6.3% (w/v);
(b) then adding a certain amount of Ag NWs and TiO mixed in the step 32 NS suspension, Ag NWs and TiO in coating liquid2 The mass fraction of NS is 0.5-25.0% of chitosan;
(c) stirring for 24 hours to prepare Ag NWs-TiO2 NS modified chitosan composite bactericidal coatingAnd (3) a membrane.
Comparative example 1:
the eggs were washed with clear water and air-dried, labeled as CK1, and stored at 25 ℃.
Comparative example 2:
ag and TiO of the prior art2The combined bactericidal coating was a comparative example, designated CK 2. The specific preparation method of the bactericidal coating comprises the following steps:
taking 0.8mmol nano silver and 0.6mmol nano TiO2Adding 20mL of acetic acid, and strongly stirring to obtain the bactericidal coating.
Comparative example 3:
ag and TiO in the prior art2The chitosan-bonded bactericidal coating film was designated as CK3 as a comparative example. The specific preparation method of the bactericidal coating comprises the following steps:
taking 0.8mmol nano silver and 0.6mmol nano TiO2Adding 20mL of acetic acid and 0.5g of chitosan, and strongly stirring to obtain the bactericidal coating.
In the invention, the weight loss rate test method comprises the following steps: each egg is weighed before and during storage. And the mass of the eggs before and during storage is recorded as m0And mt. The weight loss rate of the eggs was calculated according to the following formula: Δ m% (m0-mt)/m0 × 100%.
The weight loss test results are shown in table 1, and the influence of the coating treatment on the weight loss can be obtained from the test results in table 1.
Table 1 influence of composite nano-coating treatment on weight loss ratio
The lower the weight loss rate, the better the preservation effect of the eggs. As can be seen from the weight loss rate test results in Table 1, the film coating agent provided by the invention can effectively reduce the weight loss rate of eggs and improve the egg preservation effect.
The composite bactericidal material obtained in the first to fourth embodiments of the invention, four control samples and three control samples are respectively subjected to bacteriostasis experiments, and the experiment steps are as follows: (1) staphylococcus aureusOr inoculating Escherichia coli into a nutrition dish, and activating at 37 deg.C. (2) The cultured streptococcus liquid is placed in a sterile beaker, and 9 groups are respectively taken, wherein one group is a control group. (3) Placing the materials in 8 groups of bacterial solutions respectively: the first four groups contain prepared sterilizing materials with different concentrations, and the second four groups respectively and independently contain Ag NWs-TiO2 NS a, Ag NWs-chitosan b, TiO2 NS-chitosan c and chitosan d alone, control group were put in equal amount of clear water. (4) And observing and counting by using a flat plate counting method, and calculating by using a sterilization rate formula. The following table is a bactericidal chart for 11 experiments.
TABLE 2 Bactericidal Effect of composite Nano coating film
As shown in Table 2, Ag NWs-chitosan and TiO2 NS-chitosan and Ag NWs-TiO2 The NS-chitosan composite nano material has good inhibition effect on staphylococcus or escherichia coli. After the nano silver and the nano titanium dioxide are compounded, the nano silver-titanium dioxide composite coating film has a synergistic bactericidal effect, the antibacterial performance of the obtained nano silver-titanium dioxide composite coating film is obviously enhanced, the killing rate of bacteria is higher than 89.02%, and the bactericidal rate in the comparative example is only 82.67%. Therefore, the nano silver-titanium dioxide composite coating has excellent sterilization and disinfection performance. Therefore, the nano silver-titanium dioxide composite coating is added into the chitosan coating subsequently, the sterilization rate of the chitosan coating is higher than 99.99 percent, and the sterilization rate of the chitosan coating is only 88.96 percent in the comparative example, so that the sterilization and disinfection performance of the composite chitosan coating, which is used for preserving eggs one by one, of the final product is improved.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that a person skilled in the art could make several improvements, modifications and improvements without departing from the principle of the invention, and such improvements, modifications and improvements should also be considered as the protection scope of the present invention.
Claims (9)
1. An Ag NWs-TiO2 NS modified chitosan composite bactericidal coating,the method is characterized in that: first, TiO is prepared2Nanosheet (TiO)2 NS); secondly, depositing Ag nano-wires (Ag NWs) on the TiO by a reduction method2Nano-sheets; finally, a series of Ag NWs-TiO with different concentrations were prepared by adding a certain amount of Chitosan (CS)2 And (3) performing NS/chitosan composite coating.
2. Ag NWs-TiO2 The preparation method of the NS modified chitosan composite bactericidal coating is characterized by comprising the following specific steps:
step 1: TiO22Nanosheet (TiO)2 NS) preparation
(a) Mixing tetrabutyl titanate and 30 mL hydrochloric acid with different concentrations, and magnetically stirring for 10-40 min;
(b) adding 0.1-0.6 g ammonium hexafluorotitanate into the solution, and stirring for 30-50 min;
(c) transferring the solution into a polytetrafluoroethylene lining;
(d) placing the reaction kettle in an oven, keeping the reaction kettle at 160 ℃ for 12 hours, and taking out a sample when the temperature is reduced to room temperature;
(e) repeatedly cleaning with clear water, and oven drying in oven at 80 deg.C to obtain TiO2Nanosheets;
step 2: preparation of Ag nanowires (Ag NWs)
(a) Accurately weighing polyvinylpyrrolidone (PVP, with different molecular weights) and silver nitrate (AgNO)3) And sequentially adding the mixture into a flask;
(b) adding 80mL of glycol, and stirring gently for 5-25 min;
(c) then heating the solution at 180 ℃ for 6 hours, and cooling the solution to room temperature in a glass dryer;
(d) finally, washing the obtained product with acetone and ethanol for several times, and then storing the product in ethanol for later use;
and step 3: ag NWs-TiO2Preparation of NS composite bactericidal coating
TiO prepared by the previous step2Firstly, immersing the nanosheets into the ethanol solution of Ag NWs with a certain concentration obtained in the step 2, stirring at room temperature for reacting for 6 hours to obtain Ag NWs-TiO2NS composite bactericidal paint;
and 4, step 4: ag NWs-TiO2 Preparation of NS/Chitosan (CS) composite bactericidal coating film
(a) Weighing a certain amount of chitosan, adding the chitosan into 0.5-12.6% acetic acid solution, uniformly stirring, and preparing pure chitosan coating solution with the concentration of 0.1-6.3% (w/v);
(b) then adding a certain amount of Ag NWs and TiO mixed in the step 32 NS suspension, Ag NWs and TiO in coating liquid2 The mass fraction of NS is 0.5-25.0% of chitosan;
(c) stirring for 24 hours to prepare Ag NWs-TiO2 NS modified chitosan composite bactericidal coating.
3. Ag NWs-TiO according to claim 22 The preparation method of the NS modified chitosan composite bactericidal coating is characterized in that the concentration of the hydrochloric acid solution is 1.2, 2.4, 3.6, 4.0, 4.8, 5.2, 5.6, 6.6, 7.6, 9.1, 10.6, 12.6, 15.0 and 20.0 mol/L.
4. Ag NWs-TiO according to claim 22 The preparation method of the NS modified chitosan composite bactericidal coating is characterized in that the concentration of the butyl titanate aqueous solution is 0.02-0.6 mol/mL.
5. Ag NWs-TiO according to claim 22 The preparation method of the NS modified chitosan composite bactericidal coating is characterized in that the AgNO is3The solution concentrations were 0.2, 0.4, 0.6 and 0.8 m/L.
6. Ag NWs-TiO according to claim 22 The preparation method of the NS modified chitosan composite bactericidal coating is characterized in that the molecular weight of the polyvinylpyrrolidone is 8000-1300000.
7. Ag NWs-TiO according to claim 22 The preparation method of the NS modified chitosan composite bactericidal coating is characterized in that the mass volume of the chitosan solution isThe concentration is preferably 0.1% to 6.3%, more preferably 0.2% to 0.8%, and still more preferably 0.4% to 0.6%.
8. Ag NWs-TiO according to claim 22 The preparation method of the NS modified chitosan composite bactericidal coating is characterized in that the solvent of the chitosan solution is preferably acetic acid.
9. Ag NWs-TiO according to claim 22 The preparation method of the NS modified chitosan composite bactericidal coating is characterized in that the acetic acid is preferably provided in the form of an acetic acid solution, and the volume concentration of the acetic acid solution is preferably 0.5-12.6%, more preferably 1.2-5.6%, and more preferably 2.1-3.2%.
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| CN111903750A (en) * | 2020-07-16 | 2020-11-10 | 桂林理工大学 | Composite chitosan coating film for poultry egg preservation, preparation method and application thereof |
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