CN115179379A

CN115179379A - Preparation method of food-grade antibacterial and mildewproof wood

Info

Publication number: CN115179379A
Application number: CN202210815215.3A
Authority: CN
Inventors: 葛鹏; 惠欣; 任碧莹; 贾向坤; 宁静
Original assignee: Western Metal Material Co ltd
Current assignee: Western Metal Material Co ltd
Priority date: 2022-07-08
Filing date: 2022-07-08
Publication date: 2022-10-14

Abstract

The invention provides a preparation method of food-grade antibacterial and mildewproof wood, and relates to the technical field of wood treatment. The preparation method of the food-grade antibacterial mildewproof wood provided by the invention comprises the following steps: soaking wood to be treated in a zinc salt aqueous solution to obtain zinc ion-containing wood; putting the zinc ion-containing wood into an alkaline precipitator solution, carrying out double decomposition reaction, and heating the obtained reaction product at high temperature to obtain zinc oxide-loaded wood; soaking the wood loaded with the zinc oxide in a silver salt aqueous solution to obtain silver ion-containing wood; and (3) placing the silver ion-containing wood into a reducing agent water solution, and carrying out reduction reaction to obtain the food-grade antibacterial mildew-proof wood. The ZnO-Ag ultrafine nano particles are prepared from the raw materials on the surface and in the interior of the wood, and the pore channels of the wood have relatively closed structures, so that the antibacterial and mildewproof durability of the wood is greatly improved.

Description

Preparation method of food-grade antibacterial and mildewproof wood

Technical Field

The invention relates to the technical field of wood treatment, in particular to a preparation method of food-grade antibacterial and mildewproof wood.

Background

Wood is one of the oldest materials used by humans. Even in the highly developed industrial civilization today, wood, an ancient and vital material, still plays an irreplaceable role in life due to the characteristics of 'green' and 'environmental protection', and is widely applied to the fields of packaging and transportation, home buildings, building decoration, furniture floors, kitchen utensils and the like. However, wood, as a natural biological material, is easily attacked by mold and is a hotbed to which microorganisms adhere. Especially in the rainy season, the progress of wood utensil mildew is aggravated by humid air, the risk of disease entrance is greatly increased, food poisoning, acute diarrhea and various infectious diseases follow after. This problem seriously affects our health and therefore the demand of the consumer market for food grade antibacterial and mildewproof wooden furniture is growing rapidly.

Common antibacterial mildew inhibitors include oil type (coal tar, coal tar creosote and the like), organic type (pentachlorophenol, copper naphthenate and the like) and water-borne type (ammonia-soluble quaternary copper, copper dimethyl dithiocarbamate and the like), the application range of the common antibacterial mildew inhibitors is limited due to high toxicity and environmental pollution, and the water-borne type antibacterial mildew inhibitors have unsatisfactory effect and unstable performance and cannot play a good protection role. The inorganic antibacterial material has the advantages of high safety, good heat resistance, good durability, difficult generation of drug resistance and the like, and is developed and applied continuously since the 80 s of the 20 th century. Among them, inorganic antibacterial agents represented by nano silver and nano zinc oxide have been studied more extensively and intensively.

The nano-silver antibacterial agent combines the dual advantages of the inorganic antibacterial material and the nano-antibacterial material, has the advantages of large specific surface area, high surface reaction activity, more surface active centers, high catalytic efficiency, strong adsorption capacity and the like, and is considered to be a nontoxic and environment-friendly antibacterial material. Chinese patent CN106977969A provides an antibacterial and mildew-proof wood fiber chopping block and a preparation method thereof, wherein wood fibers are used as a base material, and nano-silver is attached to the base material as an antibacterial agent, so that the effects of mildew resistance, antibacterial and bacteriostatic properties, no cracking and the like are realized, wherein the base material comprises wood fibers, lignin and water-based resin. The product described in this patent is formed by high temperature pressing and has a high density but still risks cracking, the occurrence of large amounts of debris, etc. Chinese patent CN109591136A provides a method for preparing nano-silver antibacterial wood composite material, which utilizes a vacuum pressurization method to add nano-silver particles into wood, and squeezes the nano-silver particles into wood pores by changing the pressure intensity of the nano-silver and other factors, thereby maximally improving the weight gain rate of the wood, wherein the spherical nano-silver filled wood is beneficial to filling, the antibacterial effect is good, the antibacterial rate is 93.5%, the minimum inhibitory concentration MIC value is 500ppm, and the nano-silver concentration is increased along with the reduction of the nano-silver particles, so that the antibacterial capability of the wood can be improved. However, the bacteriostatic wood prepared by the method consumes a large amount of nano silver ions, and the cost is high.

The nano zinc oxide has good thermal stability and durability, particularly, the zinc element is an essential trace element for human bodies, has good compatibility with the human bodies, has low price, and has strong killing or inhibiting effect on pathogenic bacteria such as escherichia coli, staphylococcus aureus, salmonella and the like. Chinese patent CN103481345A discloses a method for microwave hydrothermal synthesis of zinc oxide nanostructure modified wood, which comprises preparing nano zinc oxide on the surface of wood by microwave hydrothermal synthesis, preparing zinc oxide seed crystal colloidal solution, preparing wood with zinc oxide seed crystal growing on the surface, and finally placing the wood into aqueous solution formed by mixing zinc salt and ammonia source for microwave hydrothermal reaction to complete microwave hydrothermal synthesis method for preparing nano zinc oxide on the surface of wood. The wood modified by the nano zinc oxide not only completely maintains the texture and the structure of the wood, but also hardly changes color, and can be widely applied to places with high requirements on ultraviolet resistance, antibacterial property, flame retardance and the like of the wood. However, the method for preparing the wood has higher equipment requirement and is not beneficial to industrial production.

With the research on the antibacterial performance of the nano particles, people gradually find that the ZnO-Ag composite nano particles have stronger antibacterial performance. The composite material has the advantages that zinc oxide generates photon-generated carriers (electron-hole pairs) under the excitation of ultraviolet light, and further generates free radicals with strong oxidizing property so as to kill bacteria and viruses, but the photon-generated carriers of pure zinc oxide have short service life and low photocatalysis efficiency, and the silver nanoparticles can promote electrons to be transferred from the zinc oxide to the silver nanoparticles, so that the service life of the photon-generated carriers is greatly prolonged, and the photocatalysis performance is enhanced. In addition, zinc oxide can only respond to ultraviolet light, but the surface plasmon resonance phenomenon of silver nanoparticles can absorb almost the whole visible light spectrum, and electron transfer occurs between the silver nanoparticles and zinc oxide to generate a photocatalytic effect, and the phenomenon is called plasma sensitization. Based on the advantages, the research of the composite antibacterial agent is widely concerned by the students, and the composite antibacterial agent has great potential application value in the fields of antibacterial plastics, antibacterial fibers, antibacterial ceramics, antibacterial wood and the like.

At present, the main methods for preparing the ZnO-Ag composite antibacterial agent are an in-situ synthesis method and a loading method. The former uses zinc salt and silver salt to directly react to obtain a precursor or a mixed solution, and then the ZnO-Ag composite nano particles are obtained by a hydrothermal or calcining method. The latter adopts ion sputtering method, ultraviolet light reduction method, dipping high temperature roasting method and the like to load the nano silver particles on the surface of the prepared nano zinc oxide. However, the ZnO-Ag composite antibacterial agents prepared by the two methods still have a great number of defects in the practical aspect. Firstly, znO-Ag can be effectively combined with a matrix through an in-situ synthesis method, but only a small amount of silver antibacterial agent can be exposed on the surface, and most of silver in a bulk phase cannot exert the effect; the ZnO-Ag composite nano particle obtained by the indirect loading method has larger particles, weak binding force between a solid phase and a matrix and easy loss of the antibacterial agent. In addition, the current preparation process has the problems of complex process, high requirement on equipment, inconvenience for large-scale production and the like.

Disclosure of Invention

The invention aims to provide a preparation method of food-grade antibacterial and mildewproof wood, which utilizes the structure and space confinement effect of the wood to prepare ZnO-Ag ultrafine nanoparticles and realizes high-dispersity in-situ loading on the surface of the wood within a certain depth range; because the pore canal of the wood has a relatively closed structure, the solution distribution is limited, thereby overcoming the agglomeration of the precipitated particles under the condition of not adding other components, and the ZnO-Ag superfine nano particles precipitated in situ have strong binding force with the matrix and are not easy to lose. The preparation method provided by the invention has the advantages of simpler process, lower requirement on equipment, contribution to industrial production and bright prospect in processing and application of various antibacterial woods.

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

the invention provides a preparation method of food-grade antibacterial and mildewproof wood, which comprises the following steps:

soaking wood to be treated in a zinc salt aqueous solution to obtain zinc ion-containing wood;

placing the wood containing zinc ions in an alkaline precipitator solution, carrying out double decomposition reaction, and heating the obtained reaction product at high temperature to obtain the wood loaded with zinc oxide;

soaking the wood loaded with the zinc oxide in a silver salt aqueous solution to obtain silver ion-containing wood;

and (3) placing the silver ion-containing wood into a reducing agent water solution, and carrying out reduction reaction to obtain the food-grade antibacterial mildew-proof wood.

Preferably, the zinc salt in the zinc salt aqueous solution comprises one or more of zinc nitrate, zinc acetate and zinc chloride; the concentration of the zinc salt water solution is 0.5-5 mol/L.

Preferably, the weight of the zinc ion-containing wood is increased by 15 to 70 percent compared with the wood to be treated.

Preferably, the alkaline precipitant in the alkaline precipitant solution comprises one or more of NaOH, KOH and ammonia water.

Preferably, the temperature of the double decomposition reaction is 20-45 ℃, and the time of the double decomposition reaction is 1-24 h; the high-temperature heating temperature is 90-120 ℃, and the heat preservation time is 5-6 h.

Preferably, the silver salt in the aqueous silver salt solution comprises silver nitrate; the concentration of the silver salt aqueous solution is 0.001-0.05 mol/L.

Preferably, the weight of the wood containing silver ions is increased by 15 to 70 percent compared with the wood loaded with zinc oxide.

Preferably, the reducing agent in the reducing agent aqueous solution comprises one or more of sodium borohydride, trisodium citrate, ascorbic acid, glucose, ethylene glycol and dextran; the concentration of the reducing agent aqueous solution is 0.01-1 mol/L.

Preferably, the temperature of the reduction reaction is 20-45 ℃; the time of the reduction reaction is 1-24 h.

Preferably, the reduction reaction further comprises: and washing and drying the obtained wood in sequence to obtain the food-grade antibacterial mildew-proof wood.

The invention provides a preparation method of food-grade antibacterial and mildewproof wood, which comprises the following steps: soaking wood to be treated in a zinc salt aqueous solution to obtain zinc ion-containing wood; putting the zinc ion-containing wood into an alkaline precipitator solution, carrying out double decomposition reaction, and heating the obtained reaction product at high temperature to obtain zinc oxide-loaded wood; soaking the wood loaded with the zinc oxide in a silver salt aqueous solution to obtain silver ion-containing wood; and (3) placing the silver ion-containing wood into a reducing agent water solution, and carrying out reduction reaction to obtain the food-grade antibacterial mildew-proof wood. The invention utilizes the structure and space confinement effect of wood to prepare ZnO-Ag ultrafine nano particles on the surface and the interior of the wood, and the pore channels of the wood have a relatively closed structure, so that the solution distribution is limited, thereby overcoming the agglomeration of precipitated particles under the condition of not adding other components, and greatly improving the durability of the wood in antibiosis and mildew prevention by detecting that the penetration depth is more than 3.5mm. In the invention, the silver nanoparticles can promote electrons to be transferred from zinc oxide to the silver nanoparticles, the service life of a photon-generated carrier is greatly prolonged, the photocatalytic performance is enhanced, and the silver nanoparticles and the zinc oxide are subjected to electron transfer to generate a photocatalytic effect.

Preferably, the preparation method of the invention is completed at a lower temperature, additional pressurization and microwave radiation are not needed, no energy waste is caused, the production process is simple and easy to implement, the production period is short, the adopted equipment is simple and cheap, and the industrial production is easy to realize.

Drawings

FIG. 1 is an enlarged scanning electron microscope image of food grade antibacterial and mildewproof wood prepared in example 1, magnified 3000 times;

FIG. 2 is an enlarged scanning electron microscope image of food grade antibacterial and mildewproof wood prepared in example 1, magnified 6500 times;

FIG. 3 is an X-ray photoelectron spectrum of the food grade antibacterial and mildewproof wood prepared in example 1;

fig. 4 is a graph comparing the antimicrobial effect of untreated logs and the food grade antimicrobial and mildewproof wood prepared in example 1.

Detailed Description

putting the zinc ion-containing wood into an alkaline precipitator solution, carrying out double decomposition reaction, and heating the obtained reaction product at high temperature to obtain zinc oxide-loaded wood;

In the present invention, unless otherwise specified, the starting materials for the preparation are commercially available products well known to those skilled in the art.

The wood to be treated is soaked in the zinc salt aqueous solution to obtain the zinc ion-containing wood. In the invention, the zinc salt in the zinc salt aqueous solution preferably comprises one or more of zinc nitrate, zinc acetate and zinc chloride; the concentration of the aqueous solution of zinc salt is preferably 0.1 to 5mol/L, more preferably 1 to 1.5mol/L. In the present invention, the temperature of the soaking is preferably room temperature. In the present invention, the weight of the zinc ion-containing wood is preferably increased by 15 to 70%, more preferably by 45 to 60% compared to the wood to be treated. In the present invention, it is preferable that the obtained wood is repeatedly rinsed with ultrapure water after the soaking.

After the zinc ion-containing wood is obtained, the zinc ion-containing wood is placed in an alkaline precipitator solution for double decomposition reaction, and the obtained reaction product is heated at high temperature to obtain the zinc oxide-loaded wood. In the present invention, the alkaline precipitant in the alkaline precipitant solution preferably comprises one or more of NaOH, KOH, and ammonia water. In the present invention, when the alkaline precipitant is NaOH or KOH, the concentration of the alkaline precipitant solution is preferably 0.1 to 0.8mol/L, more preferably 0.1 to 0.2mol/L. In the present invention, when the alkaline precipitant is ammonia water, the alkaline precipitant solution is preferably ammonia water having a mass concentration of 25 to 28%. The invention has no special requirement on the dosage of the alkaline precipitator solution, and the wood containing zinc ions can be immersed.

In the present invention, the temperature of the metathesis reaction is preferably 20 to 45 ℃; the time for the metathesis reaction is preferably 1 to 24 hours, more preferably 2 to 3 hours. According to the invention, after the double decomposition reaction, the obtained wood is washed clean until the effluent is neutral, so as to obtain a reaction product.

The invention heats the reaction product at high temperature to obtain the wood loaded with zinc oxide. In the present invention, the high-temperature heating temperature is preferably 90 to 120 ℃, and more preferably 100 to 120 ℃; the holding time is preferably 5 to 6 hours. In the present invention, the water content of the wood loaded with zinc oxide is preferably 10 to 20%.

After the wood carrying the zinc oxide is obtained, the wood carrying the zinc oxide is placed in a silver salt aqueous solution for soaking, and the wood containing silver ions is obtained. In the present invention, the silver salt in the aqueous silver salt solution preferably comprises silver nitrate; the concentration of the silver salt aqueous solution is preferably 0.001 to 0.05mol/L, and more preferably 0.01 to 0.015mol/L. In the present invention, the temperature of the soaking is preferably 40 to 50 ℃. In the invention, the silver ion-containing wood is preferably increased by 15-70% compared with the zinc oxide-loaded wood, and more preferably increased by 38-56%. In the present invention, it is preferable that the obtained wood is repeatedly rinsed with ultrapure water after the soaking. In the invention, when the wood carrying the zinc oxide is immersed in the silver salt aqueous solution, the concentration difference between the inside and the outside of the wood chip is larger, the particles are diffused from the solution with higher concentration to the inside of the wood, the immersion temperature is properly increased, the diffusion speed can be improved, and the sample and the solution are not influenced.

After the silver ion-containing wood is obtained, the silver ion-containing wood is placed in a reducing agent aqueous solution for reduction reaction, and the food-grade antibacterial mildewproof wood is obtained. In the present invention, the reducing agent in the reducing agent aqueous solution preferably comprises one or more of sodium borohydride, trisodium citrate, ascorbic acid, glucose, ethylene glycol and dextran; the concentration of the aqueous reducing agent solution is preferably 0.01 to 1mol/L, and more preferably 0.2 to 0.5mol/L. The method has no special requirement on the dosage of the reducing agent aqueous solution, and the silver ion-containing wood can be immersed.

In the present invention, the temperature of the reduction reaction is preferably 20 to 45 ℃, more preferably 30 to 40 ℃; the time for the reduction reaction is preferably 1 to 24 hours, more preferably 2 to 3 hours.

In the present invention, it is preferable that the reduction reaction further comprises: and washing and drying the obtained wood in sequence to obtain the food-grade antibacterial mildew-proof wood. In the present invention, the washing is preferably water washing. In the present invention, the drying preferably includes a first stage drying and a second stage drying which are sequentially performed. In the invention, the temperature of the first stage drying is preferably 50-80 ℃, more preferably 60-70 ℃, and the time is preferably 1-240 hours, more preferably 100-200 hours; the temperature of the second stage drying is preferably 90-120 ℃, more preferably 100-110 ℃, and the time is preferably 1-240 hours, more preferably 48-72 hours. In the present invention, the moisture content of the food grade antibacterial and mildewproof wood is preferably 10 to 18%, and more preferably 12 to 15%.

In the invention, znO-Ag ultrafine nanoparticles grow on the surface and in the interior of the food-grade antibacterial and mildewproof wood in situ; the particle size of the ZnO-Ag ultrafine nano-particles is preferably 10-500 nm. In the present invention, the ZnO-Ag ultrafine nanoparticles include ZnO nanoparticles and Ag nanoparticles supported on the ZnO nanoparticles; the mass of the ZnO nano-particles is preferably 30-60% of that of the ZnO-Ag superfine nano-particles, and the particle size of the ZnO nano-particles is preferably 100-500 nm; the Ag nano-particles preferably account for 40-70% of the mass of the ZnO-Ag ultrafine nano-particles, and the particle size of the Ag nano-particles is preferably 10-200 nm.

The food-grade antibacterial mildewproof wood prepared by the invention has the advantages of obvious antibacterial effect and long antibacterial aging. In addition, compared with other methods, the preparation method provided by the invention has the advantages of simpler process, lower requirement on equipment, no pollution, and better contribution to industrial production, and has bright prospects in processing and application of various antibacterial woods.

The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

(1) Weighing 14.8g of zinc nitrate, dissolving the zinc nitrate in 50mL of distilled water at room temperature, and placing the zinc nitrate in an ultrasonic oscillator to be stirred to be uniformly dispersed to obtain 1mol/L zinc nitrate solution; then, the dried wood is immersed in the solution at room temperature, the wood is taken out after the weight gain is 60 percent and washed clean by water, then the wood is immersed in 0.1mol/L aqueous solution of sodium hydroxide, the solution and the wood are transferred into a wood drying chamber after 3 hours, the wood is taken out after the complete reaction, and the wood is washed clean by a large amount of warm water.

(2) Weighing 0.017g of silver nitrate, dissolving the silver nitrate in 10mL of distilled water at room temperature, placing the solution in an ultrasonic oscillator, and stirring for 10min to uniformly disperse the solution to obtain 0.01mol/L silver nitrate solution; the wood samples were then immersed in an aqueous silver nitrate solution at 40 ℃.

(3) And taking out the wood which absorbs the silver nitrate water solution until the weight is increased by 56 percent, and washing the wood with water.

(4) Weighing 0.0716g of sodium borohydride, dissolving in 10mL of distilled water, stirring until the solution is uniformly dispersed without precipitation, and obtaining 0.2mol/L of sodium borohydride aqueous solution; then the wood is immersed in the sodium borohydride water solution, so that a large number of small bubbles around the wood can be clearly observed, and the small bubbles are generated due to the reduction reaction of the silver nitrate in the wood and the sodium borohydride to generate hydrogen. Subsequently, the beaker was placed in a water bath constant temperature shaker to allow for full reaction, the temperature was controlled at 30 ℃, and after 2h the wood was taken out and rinsed clean with water.

(5) Drying the wood obtained by the reduction reaction in a wood drying chamber, wherein the temperature of the first drying stage is 50 ℃, and the time is 200h; the temperature of the second drying stage is 90 ℃, the time is 72 hours, and finally the food-grade antibacterial and mildewproof wood with the water content of 15% is obtained.

Scanning electron micrographs of the food-grade antibacterial and mildewproof wood prepared in this example are shown in fig. 1-2. As can be seen from FIGS. 1-2, the nano Ag and the nano dendritic ZnO form the ZnO-Ag ultrafine nanoparticles of the composite inorganic antibacterial agent, which are uniformly distributed in the wood.

Fig. 3 is an X-ray photoelectron spectrum of the food grade antibacterial and mildewproof wood prepared in this example, and the XPS detection shows that the wood contains elemental silver and zinc oxide. Through the steps, the ZnO-Ag nano antibacterial agent loaded wood is finally obtained.

The food-grade antibacterial and mildewproof wood prepared by the embodiment has ZnO-Ag ultrafine nanoparticles growing on the surface and in the interior in situ, and the penetration depth is 4mm.

Example 2

(1) Weighing 13.76g of anhydrous zinc acetate, dissolving the anhydrous zinc acetate in 50mL of distilled water at room temperature, and placing the solution in an ultrasonic oscillator to be stirred to be uniformly dispersed to obtain a 1.5mol/L zinc acetate solution; then, soaking the dried wood in the solution at room temperature, taking out the wood after the weight is increased by 45 percent and washing the wood with water, then soaking the wood in 0.2mol/L aqueous solution of sodium hydroxide, transferring the solution and the wood into a wood drying chamber after 2 hours, keeping the solution and the wood in the drying chamber at 120 ℃ for 5 hours, taking out the wood after complete reaction, and washing the wood with a large amount of warm water.

(2) Weighing 0.0255g of silver nitrate, dissolving the silver nitrate into 10mL of distilled water at room temperature, placing the solution into an ultrasonic oscillator, and stirring for 10min to uniformly disperse the silver nitrate to obtain 0.015mol/L silver nitrate solution; the dried wood samples were then immersed in an aqueous silver nitrate solution at 30 ℃.

(3) And taking out the wood which absorbs the silver nitrate aqueous solution until the weight is increased by 38%, and washing the wood with water.

(4) Weighing 1.29g of trisodium citrate, dissolving in 10mL of distilled water, and stirring until the trisodium citrate is uniformly dispersed without precipitation to obtain 0.5mol/L trisodium citrate aqueous solution; the wood was then immersed in an aqueous solution of trisodium citrate. Subsequently, the beaker was placed in a water bath constant temperature shaker to allow sufficient reaction, the temperature was controlled at 40 ℃, and after 3 hours the wood was taken out and washed clean with water.

(5) Drying the wood obtained by the reduction reaction in a wood drying chamber, wherein the temperature of the first drying stage is 70 ℃, and the time is 100 hours; the temperature of the second drying stage is 110 ℃, the time is 48 hours, and finally the food-grade antibacterial and mildewproof wood with the water content of 12 percent is obtained.

After XPS detection, the wood is added with simple substance silver and zinc oxide components. Through the steps, the ZnO-Ag nano antibacterial agent loaded wood is finally obtained.

The food-grade antibacterial and mildewproof wood prepared by the embodiment has ZnO-Ag ultrafine nanoparticles growing in situ on the surface and inside, and the penetration depth is 3.5mm.

Test example

The food grade antibacterial and mildewproof wood prepared in example 1 was subjected to a bacteriostatic property test with untreated raw wood as a control.

Taking escherichia coli ATCC25922 as a test strain, taking a fresh culture of 18-24 h of a nutrient agar culture medium slant from the third generation to the eighth generation of the strain, sucking 3-5 mL of 0.03mol/L phosphate buffer solution by using a 5mL suction pipe, adding into a slant test tube, repeatedly washing and blowing, and washing off bacterial lawn. Transferring the washed bacterial liquid into another test tube, uniformly mixing by using an oscillator, diluting to an appropriate concentration by using 0.03mol/L phosphate buffer solution, and storing the bacterial propagule suspension in a refrigerator at 4 ℃.

5g of a control sample (untreated raw wood) and a test sample (food grade antibacterial mildewproof wood prepared in example 1) were put into a triangular flask, 95mL of phosphate buffer solution containing 0.1% Tween 80 was added, and after mixing, 5mL of the prepared bacterial suspension was added. The flasks containing the control and test samples were fixed on a shaker incubator shaker and shaken at 37 ℃ for 1h.

After the control sample liquid and the test sample liquid after shaking are properly diluted, respectively taking 1mL of sample liquid to inoculate in a sterilization plate, pouring nutrient agar culture medium which is melted at 45-55 ℃, turning over the plate after the agar culture medium is solidified, placing the plate in a constant-temperature incubator at 37 ℃, and counting viable bacteria. As shown in fig. 4, the antibacterial rate of the test sample of example 1 was 95% or more, and the control sample had no antibacterial rate. According to the antibacterial test result, the antibacterial property of the wood filled with the ZnO-Ag nano antibacterial agent is obviously improved.

The method is adopted to test the bacteriostatic performance of the food-grade antibacterial mildewproof wood prepared in the example 2, and the antibacterial rate is 99%.

In addition, tests show that the food-grade antibacterial and mildewproof wood prepared in the examples 1 and 2 still has the antibacterial effect after being soaked in water for 24 hours, and the antibacterial rate is 70%.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of food-grade antibacterial mildewproof wood comprises the following steps:

2. The preparation method of claim 1, wherein the zinc salt in the zinc salt aqueous solution comprises one or more of zinc nitrate, zinc acetate and zinc chloride; the concentration of the zinc salt aqueous solution is 0.5-5 mol/L.

3. The method according to claim 1 or 2, characterized in that the weight of the zinc ion-containing wood is increased by 15-70% compared to the wood to be treated.

4. The preparation method of claim 1, wherein the alkaline precipitant in the alkaline precipitant solution comprises one or more of NaOH, KOH and ammonia water.

5. The process according to claim 1 or 4, wherein the temperature of the metathesis reaction is 20 to 45 ℃ and the time of the metathesis reaction is 1 to 24 hours; the high-temperature heating temperature is 90-120 ℃, and the heat preservation time is 5-6 h.

6. The production method according to claim 1, wherein the silver salt in the aqueous silver salt solution comprises silver nitrate; the concentration of the silver salt aqueous solution is 0.001-0.05 mol/L.

7. The method according to claim 1 or 6, wherein the weight of the wood containing silver ions is increased by 15-70% compared with the wood loaded with zinc oxide.

8. The preparation method according to claim 1, wherein the reducing agent in the reducing agent aqueous solution comprises one or more of sodium borohydride, trisodium citrate, ascorbic acid, glucose, ethylene glycol and dextran; the concentration of the reducing agent aqueous solution is 0.01-1 mol/L.

9. The method according to claim 1 or 8, wherein the temperature of the reduction reaction is 20 to 45 ℃; the time of the reduction reaction is 1-24 h.

10. The method according to claim 1, further comprising, after the reduction reaction: and washing and drying the obtained wood in sequence to obtain the food-grade antibacterial mildew-proof wood.