A porous material-catalase removable multifunctional protective liquid, preparation method and application thereof in the protection of aged paper

Abstract

A porous material-catalase removable multifunctional protective liquid, a preparation method and its application in the protection of aged paper belong to the technical field of aged paper protection. The protective liquid is obtained by dissolving ZIF-8, ZIF-8-CAT after the morphology is adjusted by a surfactant and bacterial cellulose in deionized water. ZIF-8 is formed by mixing and growing 2-methylimidazole, zinc nitrate hexahydrate and a surfactant in an aqueous phase according to a certain proportion; ZIF-8-CAT is formed by mixing and growing 2-methylimidazole, zinc nitrate hexahydrate, catalase and a surfactant in an aqueous phase according to a certain proportion. The preparation method of the present invention is simple and fast, the reaction conditions are green and mild, it can effectively inhibit the growth of bacteria and fungi and has excellent antioxidant capacity. This protective liquid can not only provide physical support for the cellulose of aged paper, but also prevent the oxidation and fracture of cellulose while inhibiting bacteria, and can significantly extend the life of the paper.

Description

Technical Field

[0001] The present invention belongs to the technical field of aged paper protection, and in particular relates to a porous material-catalase removable multifunctional protective liquid, a preparation method and application thereof in aged paper protection. Technical Background

[0002] As a country with a long history, my country has developed diverse cultures throughout its history. Preserving cultural relics benefits both the present and future generations. Before humanity entered the digital age, paper documents served as the primary medium for conveying world culture and recording historical origins. Engraved with a wealth of historical and cultural information, they hold significant value for our heritage, historical research, and future work. However, as time passes and paper artifacts are subject to storage restrictions and other factors, such as war, at different historical periods, a large number of precious paper artifacts have inevitably experienced varying degrees of aging and damage. This has caused irreparable damage to these already fragile artifacts. Developing new methods for the non-destructive preservation of aged paper and strengthening its restoration are pressing tasks.

[0003] Aged paper manifests itself macroscopically as yellowing, brittleness, mold, and wormholes, while microscopically, it manifests as cellulose bundle breakage and a decline in mechanical properties. Acidity, alkali, high temperature, ultraviolet light, water, fire, and microorganisms are key factors contributing to the degradation of aged paper. Acidification and microbial decomposition are currently the primary causes of damage to paper artifacts. The more acidic the aged paper, the faster its cellulose degrades. Because the cellulose that makes up aged paper is inherently hygroscopic, it easily harbors microorganisms, which can cause irreversible degradation of the mechanical properties of aged paper through acid corrosion and enzymatic degradation. While commonly used antibiotics have significant antimicrobial effects, they exhibit varying degrees of toxic side effects on aged paper cellulose and may accelerate degradation, limiting their application. Currently, commonly used aged paper protectants primarily utilize organic polymers (such as starch, modified starch, and chitosan). However, these organic polymers are difficult to remove once applied to aged paper cellulose, compromising subsequent preservation and restoration efforts. Therefore, developing an environmentally friendly, removable, multifunctional aged paper protectant that combines mildew and antibacterial properties, deacidification, reinforcement, and UV protection is of great practical significance. Summary of the Invention

[0004] The present invention aims to provide a removable, multifunctional porous material-catalase protective solution, its preparation method, and its application in protecting aged paper. The removable, multifunctional protective solution not only strengthens the cellulose in aged paper but also imparts mildew, antibacterial, and antioxidant properties. By leveraging the biodegradability and UV resistance of ZIF-8 and ZIF-8-CAT (modified with surfactants), it effectively strengthens existing aged paper, provides antibacterial and mildew resistance, and provides UV protection.

[0005] The present invention provides a porous material-catalase removable multifunctional protective solution, wherein the protective solution is obtained by dissolving ZIF-8, ZIF-8-CAT after morphology adjustment by a surfactant, and bacterial cellulose (BC) in deionized water, and the concentrations thereof are 5-10 mg / mL, 1-5 mg / mL, and 0.05-0.1 mg / mL, respectively. The present invention also relates to a removal solution, wherein the removal solution is obtained by dissolving ethylenediaminetetraacetic acid (EDTA) in deionized water, and the concentration thereof is 0.5-5 mM.

[0006] The ZIF-8 is prepared by mixing and growing 2-methylimidazole, zinc nitrate hexahydrate and a surfactant in a water phase in a certain proportion.

[0007] The ZIF-8-CAT after the morphology is adjusted by a surfactant is formed by mixing and growing 2-methylimidazole, zinc nitrate hexahydrate, catalase (CAT) and a surfactant in a water phase according to a certain proportion.

[0008] (1) ZIF-8 was obtained by the following green production method: first, 0.5-2 g of zinc nitrate hexahydrate was dissolved in 10 mL of deionized water and stirred to obtain a zinc nitrate solution; then, 15-25 g of 2-methylimidazole was dissolved in 90 mL of deionized water and stirred to obtain a 2-methylimidazole solution; 0.04-0.4 g of a surfactant was added to the 2-methylimidazole solution and stirred to obtain a 2-methylimidazole / surfactant mixed solution; then, the zinc nitrate solution was quickly added to the 2-methylimidazole / surfactant mixed solution under stirring at room temperature. After 1 minute, the solution turned milky white, indicating that ZIF-8 nanoparticles had begun to form. To ensure complete crystallization, stirring was continued for 5-60 minutes; then, the solution was subjected to solid-liquid separation under centrifugation (12000-18000 rpm, 10-30 minutes), and the obtained solid was rinsed with deionized water 3-5 times to remove the unreacted reagent, and then freeze-dried to obtain ZIF-8;

[0009] The amount of zinc nitrate hexahydrate is preferably 1 to 1.5 g, and the amount of 2-methylimidazole is preferably 18 to 22 g; the surfactant is used to adjust the morphology of ZIF-8, and its purity is greater than 98%, and its amount is preferably 0.05 to 0.2 g; the surfactant is not limited to hexadecyltrimethylammonium bromide (CTAB), and the same proportion of bisdecyldimethylammonium chloride (DDAC) or benzalkonium chloride (BZC) can also achieve the same effect; the crystallization stirring time of ZIF-8 is preferably 10 to 30 min, and the centrifugation time is preferably 10 to 20 min.

[0010] (2) ZIF-8-CAT after morphology adjustment by surfactant was obtained by the following green production method: first, 0.5-2 g of zinc nitrate hexahydrate was dissolved in 10 mL of deionized water and stirred to obtain zinc nitrate solution; 15-25 g of 2-methylimidazole was dissolved in 90 mL of deionized water, and then 5 M HCl was used to adjust the pH of the solution to 9-12, and stirred to obtain 2-methylimidazole solution; 0.04-0.4 g of surfactant was added to the 2-methylimidazole solution, and stirred to obtain a 2-methylimidazole / surfactant mixed solution; then 2-methylimidazole / surfactant mixed solution was added to the 2-methylimidazole / surfactant mixed solution. 0.2-1.2 g of CAT was added to the active agent mixed solution and stirred vigorously to dissolve it rapidly. Zinc nitrate solution was then quickly added to the solution under stirring at room temperature. After 3 minutes, the solution became turbid, indicating that ZIF-8-CAT nanoparticles had begun to form. Stirring was continued for 5-60 minutes to ensure complete crystallization. The solution was then centrifuged (12,000-18,000 rpm, 10-30 minutes) to separate the solid and liquid. The resulting solid was rinsed with deionized water 3-5 times to remove unreacted reagents and lyophilized to obtain ZIF-8-CAT with surfactant-adjusted morphology.

[0011] The amount of zinc nitrate hexahydrate is preferably 1-1.5 g, and the amount of 2-methylimidazole is preferably 18-22 g; the amount of CAT is preferably 0.5-1 g; the crystallization stirring time of ZIF-8-CAT is preferably 30-40 min; the pH is preferably adjusted to 10-12 using 5M HCl solution; the centrifugation time is preferably 10-20 min; the surfactant is used to adjust the morphology of ZIF-8-CAT, and its purity is greater than 98%, and its amount is preferably 0.05-0.2 g; the surfactant is not limited to hexadecyltrimethylammonium bromide (CTAB), and the same proportion of bisdecyldimethylammonium chloride (DDAC) or benzalkonium chloride (BZC) can also achieve the same effect.

[0012] (3) Preparation of protective solution: 10 g of ZIF-8, ZIF-8-CAT after surfactant-adjusted morphology, and bacterial cellulose (BC) were dissolved in 100 mL of deionized water to obtain a protective solution; the concentrations of ZIF-8, ZIF-8-CAT after surfactant-adjusted morphology, and bacterial cellulose (BC) were 5-10 mg / mL, 1-5 mg / mL, and 0.05-0.1 mg / mL, respectively, with preferred concentrations being 6-7 mg / mL, 3-4 mg / mL, and 0.05-0.1 mg / mL, respectively; the size of the bacterial cellulose (BC) was 150-250 nm;

[0013] (4) Preparation of a removal solution: dissolving ethylenediaminetetraacetic acid (EDTA) solid powder in deionized water to obtain a removal solution, wherein the concentration of the EDTA solution is 0.5 to 5 mM, preferably 1 to 3 mM;

[0014] (5) The protective liquid can be effectively used to strengthen and protect aged paper. The method of use is: spray the protective liquid evenly on the surface of the aged paper or immerse the aged paper in the protective liquid at 10-40°C for 5-30 minutes, then take it out and dry it at 20-40°C for 2-5 days.

[0015] The soaking time of the aged paper in the protective liquid is preferably 5 to 10 minutes; the soaking temperature of the aged paper in the protective liquid is preferably 25 to 35°C, the drying temperature is preferably 30 to 40°C, and the drying time is preferably 2 to 3 days;

[0016] The protective liquid is used to strengthen, inhibit bacteria, resist oxidation and flame retard the aged paper cellulose; and is used to inhibit one or more of Staphylococcus aureus, Escherichia coli, Aspergillus niger, Penicillium, Trichoderma and Fusarium in the aged paper;

[0017] (6) The method for removing the protective liquid from the aged paper is as follows: soak the aged paper reinforced with the protective liquid in a removal liquid at 20 to 30°C for 5 to 20 minutes, then take it out and dry it at 20 to 40°C for 2 to 5 days.

[0018] The aged paper is preferably immersed in the removal liquid for 5 to 10 minutes, the aged paper is preferably dried at a temperature of 30 to 40° C., and the drying time is preferably 2 to 3 days.

[0019] Compared with the existing aging paper protection liquid, the present invention has the following characteristics:

[0020] 1) The morphology of ZIF-8-CAT in the protective solution was adjusted by using surfactant to make it an octahedron with two regular hexagonal faces ( Figure 1 b) enhancing its reinforcing and supporting effect on aged paper cellulose;

[0021] 2) ZIF-8 / ZIF-8-CAT / BC removable multifunctional protective liquid can effectively protect aged paper cellulose from UV damage;

[0022] 3) ZIF-8 and ZIF-8-CAT have dual antibacterial effects, effectively inhibiting and killing bacteria and fungi on the surface of aged paper, thus preventing microbial damage to aged paper;

[0023] 4) ZIF-8-CAT can effectively remove H2O2 produced on the surface of aged paper cellulose, preventing the oxidation and fracture of aged paper cellulose, and extending the life of cellulose through antioxidant means;

[0024] 5) The addition of BC to the protective solution not only enhances the dispersibility of ZIF-8 and ZIF-8-CAT in the solution, helping to make the protective solution more evenly distributed among the cellulose fibers in the aged paper, but also connects the broken cellulose fibers in the aged paper through hydrogen bonding interactions;

[0025] 6) Removal liquid B can remove the protective liquid without damaging the aged paper cellulose, achieving sustainable protection and restoration of precious paper cultural relics. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 a: SEM spectrum of ordinary ZIF-8-CAT (Du, YJ; Gao, J.; Zhou, LY; Ma, L.; He, Y.; Huang, ZH; Jiang, YJ) Enzyme nanocapsules armored by metal-organic frameworks: A novel approach for preparing nanobiocatalyst. Chemical Engineering Journal2017,327,1192-1197,doi:10.1016 / j.cej.2017.07.021); Figure 1 b: SEM spectrum of ZIF-8-CAT (corresponding to the product of step (2) of Example 1) after morphology adjustment by CTAB; Figure 1 c: SEM spectrum of protective solution; Figure 1 d: SEM spectrum of the aged paper after the protective solution was applied;

[0027] Figure 2 : Element distribution diagram of ZIF-8-CAT after morphology adjustment by CTAB obtained in Example 1 (the inset is the percentage of each element); the abscissa is energy and the ordinate is intensity;

[0028] Figure 3: FTIR spectra of CAT, ZIF-8, and ZIF-8-CAT after morphology adjustment by CTAB; the abscissa is the wavelength, and the ordinate is the transmittance;

[0029] Figure 4 : XRD characterization diagram of ZIF-8 and ZIF-8-CAT after morphology adjustment by CTAB; the abscissa is the scanning degree, and the ordinate is the intensity;

[0030] Figure 5 a: Growth curves of gram-positive bacteria (E. coli) treated with CTAB-modified ZIF-8-CAT at concentrations of 0 mg / mL, 0.2 mg / mL, 0.4 mg / mL, 0.6 mg / mL, 0.8 mg / mL, 1.0 mg / mL, and 2.0 mg / mL, respectively; the abscissa is time, and the ordinate is absorbance at 600 nm.

[0031] Figure 5 b: Growth curves of gram-negative bacteria (S. aureus) treated with CTAB-modified ZIF-8-CAT at concentrations of 0 mg / mL, 0.2 mg / mL, 0.4 mg / mL, 0.6 mg / mL, 0.8 mg / mL, 1.0 mg / mL, and 2.0 mg / mL, respectively; the abscissa is time, and the ordinate is absorbance at 600 nm.

[0032] Figure 6 a: Photos of the inhibitory effects of ZIF-8-CAT at a concentration of 10 mg / mL after CTAB adjustment and ZIF-8 at a concentration of 10 mg / mL on Gram-positive bacteria (E. coli) and Gram-negative bacteria (S. aureus);

[0033] Figure 6 b: Bar graph of the inhibition zone size of ZIF-8-CAT with CTAB adjustment at a concentration of 10 mg / mL and ZIF-8 at a concentration of 10 mg / mL against Gram-positive bacteria (E. coli) and Gram-negative bacteria (S. aureus); the horizontal axis is the antibacterial material and the vertical axis is the inhibition zone size;

[0034] Figure 7 a: Photograph showing the inhibitory effect of the protective solution prepared in Example 2 on Penicillium citrinum;

[0035] Figure 7 b: Photograph showing the inhibitory effect of the protective solution prepared in Example 2 on Aspergillus;

[0036] Figure 7 c: Photograph showing the inhibitory effect of the protective solution prepared in Example 2 on Fusarium;

[0037] Figure 7 d: Photograph showing the inhibitory effect of the protective solution prepared in Example 2 on Pseudomonas;

[0038] Figure 8 a: Concentration-activity curves of ZIF-8-CAT at concentrations of 0.02 mg / mL, 0.04 mg / mL, 0.06 mg / mL, 0.08 mg / mL, 0.1 mg / mL, 0.2 mg / mL, and 0.5 mg / mL, respectively, after morphology adjustment by CTAB. The abscissa represents the concentration of ZIF-8-CAT, and the ordinate represents the activity (U) of ZIF-8-CAT. The higher the activity (U) of ZIF-8-CAT, the faster the rate of scavenging H2O2.

[0039] Figure 8 b: Double reciprocal curves of H2O2 concentration-scavenging rate when the concentrations of ZIF-8-CAT after CTAB adjustment are 0.02 mg / mL, 0.04 mg / mL, 0.06 mg / mL, 0.08 mg / mL, 0.1 mg / mL, 0.2 mg / mL and 0.5 mg / mL respectively; the abscissa is 1 / [S] and the ordinate is 1 / v;

[0040] Figure 9 a: Curve showing the effect of temperature on the activity of ZIF-8-CAT after morphology adjustment by CTAB; the horizontal axis represents temperature, and the vertical axis represents the percentage of optimal activity at different temperatures; the optimal activity at 35°C is set as 100%, and the relative enzyme activity at each temperature is obtained by dividing the activity of ZIF-8-CAT at other temperatures by the optimal activity at 35°C and multiplying by 100%.

[0041] Figure 9 b: Effect of pH on the activity of ZIF-8-CAT after morphology adjustment by CTAB at 35°C; the horizontal axis is pH, and the vertical axis is the percentage of activity under different pH conditions and the optimal pH;

[0042] Figure 10 a: Degradation curve of ZIF-8-CAT after morphology adjustment by CTAB by removal solution; the horizontal axis is wavelength and the vertical axis is absorbance;

[0043] Figure 10 b: Degradation kinetics curve of ZIF-8-CAT after CTAB-adjusted morphology by removal solution; the abscissa is time, and the ordinate is absorbance at a wavelength of 207 nm;

[0044] Figure 11 : Bar graph of pH values ​​of the removal solution corresponding to different EDTA concentrations; the horizontal axis is EDTA concentration, and the vertical axis is pH value;

[0045] Figure 12 : Example 1 Removal of the protective liquid applied to the aged paper and SEM image of the cellulose of the aged paper after drying;

[0046] Figure 13 : Example 2: SEM image of cellulose in aged paper after removing the protective liquid applied on the aged paper and drying;

[0047] Figure 14 : Example 3 Removal of the protective liquid applied on the aged paper SEM image of the cellulose of the aged paper after removal and drying. DETAILED DESCRIPTION

[0048] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0049] Example 1

[0050] (1) Green synthesis of ZIF-8: First, 1.0 g of zinc nitrate hexahydrate was dissolved in 10 mL of deionized water and stirred to obtain a zinc nitrate solution; 19.4 g of 2-methylimidazole was dissolved in 90 mL of deionized water and stirred to obtain a 2-methylimidazole solution; 0.05 g of CTAB was added to the 2-methylimidazole solution and stirred to obtain a 2-methylimidazole / CTAB mixed solution; the zinc nitrate solution was then quickly added to the 2-methylimidazole / CTAB solution under stirring at room temperature. After 1 minute, the solution turned milky white, indicating that ZIF-8 nanoparticles had begun to form. To ensure complete crystallization, stirring was continued for 10 minutes; the solution was then separated into solid and liquid using a centrifuge (15,000 rpm, 10 minutes), and the obtained solid was washed three times with deionized water to remove the unreacted reagents; ZIF-8 was obtained after freeze-drying, with a product mass of approximately 3 g.

[0051] (2) ZIF-8-CAT after morphology adjustment by CTAB was obtained by the following green production method: First, 1.0 g of zinc nitrate hexahydrate was dissolved in 10 mL of deionized water and stirred to obtain a zinc nitrate solution; 19.4 g of 2-methylimidazole was dissolved in 90 mL of deionized water, and then the pH was adjusted to 12 using 5 M HCl solution, and stirred to obtain a 2-methylimidazole solution; 0.1 g of CTAB was added and stirred evenly to obtain a 2-methylimidazole / CTAB mixed solution; then 0.5 g of CAT was added to the 2-methylimidazole / CTAB mixed solution and stirred vigorously to dissolve it quickly; then zinc nitrate solution was quickly added thereto under stirring at room temperature. After 3 minutes, the solution became turbid, indicating that ZIF-8-CAT nanoparticles had begun to form. To ensure complete crystallization, stirring was continued for 30 minutes; then the solution was separated into solid and liquid using a centrifuge (15000 rpm, 10 minutes), and the obtained solid was rinsed three times with deionized water to remove unreacted reagents; finally, ZIF-8-CAT with morphology adjusted by CTAB was obtained after freeze-drying, and the product mass was about 3 g.

[0052] like Figure 1 As shown in a, ordinary ZIF-8 is a rhombic dodecahedron. Figure 1 b After the morphology of ZIF-8-CAT was adjusted by CTAB, it was an octahedron with two regular hexagonal faces, indicating that the addition of surfactant CTAB can play a good role in adjusting the morphology of ZIF-8-CAT;

[0053] like Figure 2 As shown in the inset, the horizontal axis represents energy and the vertical axis represents intensity. The elemental composition is as follows: C (48.49%), N (28.35%), O (9.42%), S (0.19%), Fe (0.07%), and Zn (13.50%). While S, a protein component, is not present in ZIF-8, its presence was detected in the EDS spectrum, indicating that CAT was successfully immobilized on ZIF-8.

[0054] like Figure 3 As shown, the infrared spectra of CAT, ZIF-8 and ZIF-8-CAT after morphology adjustment by CTAB were detected using SMHADZU 3346 using the potassium bromide tablet method. The horizontal axis is wavelength and the vertical axis is transmittance. The FTIR spectra of ZIF-8 and ZIF-8-CAT are almost the same, indicating that the structures of ZIF-8 synthesized by the present invention and ZIF-8-CAT after morphology adjustment by CTAB are correct. The ZIF-8-CAT after morphology adjustment by CTAB has a wavelength of 1658 cm -1The absorption peak nearby is enhanced, which may be caused by the successful entrapment and immobilization of CAT in the ZIF-8 framework;

[0055] like Figure 4 As shown, XRD structural analysis was performed using an X-ray diffractometer from Almelo, the Netherlands, with a scanning range of 2θ = 5°-50° and Cu-K-α radiation. The horizontal axis represents the scanning degree, and the vertical axis represents the signal intensity. The experimental results show that ZIF-8 and ZIF-8-CAT, after morphology adjustment by CTAB, have the same lattice structure, confirming that immobilizing CAT within the ZIF-8 framework does not affect the lattice structure of ZIF-8-CAT after morphology adjustment by CTAB.

[0056] The ZIF-8-CAT obtained in step (2) after morphology adjustment by CTAB was dissolved in deionized water to obtain solutions with ZIF-8-CAT concentrations of 0 mg / mL, 0.2 mg / mL, 0.4 mg / mL, 0.6 mg / mL, 0.8 mg / mL, 1.0 mg / mL and 2.0 mg / mL, and then the antibacterial experiments on Gram-positive bacteria and Gram-negative bacteria were carried out. The specific experimental method is as follows: E. coli and S. aureus cultured for 12 hours were centrifuged at 3000g for 10 minutes to collect the precipitate and washed with sterile PBS. The obtained E. coli and S. aureus were diluted to 10 6 CFU / mL, then 0mg / mL, 0.2mg / mL, 0.4mg / mL, 0.6mg / mL, 0.8mg / mL, 1.0mg / mL and 2.0mg / mL of ZIF-8-CAT after CTAB morphology adjustment were added to treat E. coli and S. aureus for 1 hour. After the inhibition was completed, the bacteria were inoculated into 50mL LB liquid medium at a ratio of 1 / 1000, and cultured at 37℃ with shaking at 180rpm. 1mL of bacterial solution was taken every 2 hours to measure the OD 600nm The absorbance value at .

[0057] like Figure 5 a and Figure 5 As shown in b, the horizontal axis is time and the vertical axis is OD 600nm The experimental results show that whether it is Gram-positive bacteria or Gram-negative bacteria, as the concentration of ZIF-8-CAT increases, the bacteria 600nm The time for the absorbance value at the position to reach 2 was delayed, indicating that ZIF-8-CAT, after morphology adjustment by CTAB, had a good inhibitory effect on both Gram-positive and Gram-negative bacteria.

[0058] (3) Preparation of protective solution: 10 g of a solid mixed powder of ZIF-8, ZIF-8-CAT, and BC was dissolved in 100 mL of deionized water to obtain a protective solution; the concentrations of ZIF-8, ZIF-8-CAT, and BC were 6 mg / mL, 3.9 mg / mL, and 0.1 mg / mL, respectively.

[0059] like Figure 1 As shown in Figure c, Example 1 successfully prepared a protective solution in which ZIF-8, ZIF-8-CAT, and BC were evenly distributed within the field of view.

[0060] (3) Preparation of removal solution: Prepare 1 mM EDTA solution by dissolving 0.292 g of EDTA in 1 L of deionized water;

[0061] (4) Protective liquid can be effectively used to strengthen and protect aged paper. The method of use is: spray the protective liquid evenly on the surface of the aged paper until the aged paper is completely soaked or immerse the aged paper in protective liquid at 25℃ for 10 minutes, then take it out and dry it at 25℃ for 5 days.

[0062] like Figure 1 d shows the SEM image of the protective liquid applied to the aged paper after drying. It can be clearly seen that the ZIF-8 in the protective liquid, the ZIF-8-CAT after CTAB adjustment of morphology, and the BC are evenly distributed among the cellulose in the aged paper, playing an obvious supporting and reinforcing role for the cellulose in the aged paper.

[0063] (5) The method of using the removal liquid is as follows: soak the aged paper protected by the protection liquid in the removal liquid for 15 minutes, then take it out and dry it at 25°C for 3 days.

[0064] like Figure 12 , the protective liquid applied on the aged paper was almost completely removed, indicating that the removing liquid had a good removal effect on the protective liquid.

[0065] Example 2

[0066] (1) Green synthesis of ZIF-8: First, 1.0 g of zinc nitrate hexahydrate was dissolved in 10 mL of deionized water and stirred to obtain a zinc nitrate solution; 19.4 g of 2-methylimidazole was dissolved in 90 mL of deionized water and stirred to obtain a 2-methylimidazole solution; 0.1 g of DDAC was added to the 2-methylimidazole solution and stirred to obtain a 2-methylimidazole / DDAC mixed solution; the zinc nitrate solution was then quickly added to the 2-methylimidazole / DDAC solution under stirring at room temperature. After 1 minute, the solution turned milky white, indicating that ZIF-8 nanoparticles had begun to form. To ensure complete crystallization, stirring was continued for 10 minutes; the solution was then separated into solid and liquid using a centrifuge (15,000 rpm, 10 minutes), and the obtained solid was washed three times with deionized water to remove the unreacted reagents; ZIF-8 was obtained after freeze-drying, with a product mass of approximately 3 g.

[0067] (2) ZIF-8-CAT was obtained by the following green production method: First, 1.0 g of zinc nitrate hexahydrate was dissolved in 10 mL of deionized water and stirred to obtain a zinc nitrate solution; 19.4 g (236.3 mmol) of 2-methylimidazole was dissolved in 90 mL of deionized water, and then the pH was adjusted to 11 using a 5 M HCl solution and stirred to obtain a 2-methylimidazole solution; 0.2 g of DDAC was added and stirred evenly to obtain a 2-methylimidazole / DDAC mixed solution; then 0.5g of CAT was added to the 2-methylimidazole / DDAC mixed solution and stirred vigorously to dissolve it quickly; then zinc nitrate solution was quickly added to it under stirring at room temperature. After 3 minutes, the solution became turbid, indicating that ZIF-8-CAT nanoparticles had begun to form. To ensure complete crystallization, stirring was continued for 20 minutes; then the solution was separated into solid and liquid using a centrifuge (15000rpm, 10min), and the obtained solid was rinsed three times with deionized water to remove unreacted reagents; finally, ZIF-8-CAT with morphology adjusted by CTAB was obtained after freeze-drying, with a product mass of approximately 3g.

[0068] The ZIF-8 obtained in step (1) and the ZIF-8-CAT obtained in step (2) after morphology adjustment by CTAB were dissolved in deionized water to obtain a solution with a concentration of 10 mg / mL for both ZIF-8 and ZIF-8-CAT; then, an antibacterial experiment on Gram-positive and Gram-negative bacteria was carried out. The specific method is as follows: Determination of the inhibition zone of ZIF-8-CAT against Gram-negative and Gram-positive bacteria: First, a sterile filter paper with a diameter of 0.6 cm was soaked in a 10 mg / mL ZIF-8-CAT protective solution for use; E. coli and S. aureus cultured for 12 hours were centrifuged at 3000g for 10 minutes to collect the precipitate and washed with sterile PBS; the obtained E. coli and S. aureus were diluted to 10 6 CFU / mL, 20 μL was spread onto LB agar medium. Sterile filter paper soaked in ZIF-8-CAT protective solution was then covered on the surface of the medium. Inverted, incubated at 30°C, and photographed to document the inhibitory effect of ZIF-8-CAT on fungi and bacteria isolated from aged paper.

[0069] like Figure 6 a and Figure 6 As shown in figure b, the sizes of the inhibition zones of ZIF-8 against E.coli and S.aureus were 10.33 mm and 13.33 mm, respectively. The sizes of the inhibition zones of ZIF-8-CAT after morphology adjustment by CTAB against E.coli and S.aureus were 11.66 mm and 15.33 mm, respectively. The experimental results showed that after 12 hours of antibacterial treatment, ZIF-8-CAT after morphology adjustment by CTAB had a more significant antibacterial effect than ZIF-8, and ZIF-8-CAT after morphology adjustment by CTAB had a more significant antibacterial effect against S.aureus than against E.coli.

[0070] The ZIF-8-CAT obtained in step (2) after morphology adjustment by CTAB was dissolved in deionized water to obtain solutions with ZIF-8-CAT concentrations of 0.02 mg / mL, 0.04 mg / mL, 0.06 mg / mL, 0.08 mg / mL, 0.1 mg / mL, 0.2 mg / mL and 0.5 mg / mL, and then a H2O2 scavenging experiment was performed. The specific experimental method is as follows: 0.02 mg / mL, 0.04 mg / mL, 0.06 mg / mL, 0.08 mg / mL, 0.1 mg / mL, 0.2 mg / mL and 0.5 mg / mL of ZIF-8-CAT were added to a reaction system with a H2O2 concentration of 5 mM, respectively, and the Linewever-Burk equation was used: Calculation of K of ZIF-8-CAT and CAT m and V maxWhere V0 is the reaction rate (μM / min); V max is the maximum reaction rate (μM / min); [S] is the H2O2 concentration (mM / mL); K m The activity of an enzyme (U): Under optimal conditions (35°C), the amount of enzyme required to catalyze the conversion of 1 μmol of substrate into product per minute is defined as one activity unit, i.e. 1 U = 1 μmol / min.

[0071] like Figure 8 As shown in a, the horizontal axis is the ZIF-8-CAT concentration and the vertical axis is the ZIF-8-CAT activity (U). The experimental results show that within a certain range, as the concentration of ZIF-8-CAT after morphology adjustment by CTAB increases, the activity of ZIF-8-CAT also increases. Figure 8 As shown in b, the double reciprocal plot of the effect of concentration on ZIF-8-CAT activity is plotted, with the horizontal axis being 1 / [S] and the vertical axis being 1 / V. 1 / K can be obtained from the intercept of the straight line with the x-axis. m The absolute value of 1 / V max is the intercept of the line with the y-axis. m =0.00588±0.000815,V max =33478.1±815.94U.

[0072] The effect of temperature on the activity of ZIF-8-CAT was determined by adding 50 μL of 10 mg / mL ZIF-8-CAT solution into a Tris-HCl buffer solution containing 5 mM H2O2 and pH 7. 240nm The reaction kinetic curve within 100s was measured at 15-65℃. The method for determining the effect of temperature on CAT activity was as follows: 50μL of 5mg / mL CAT solution was added to Tris-HCl buffer containing 5mM H2O2, pH 7, and the reaction was carried out at a temperature of 15-65℃ and an OD of 100s. 240nm The reaction kinetics curve within 300s was measured.

[0073] like Figure 9 As shown in a, CAT has good enzyme activity in the temperature range of 15-45°C, and the optimal reaction temperature is 35°C; ZIF-8-CAT after morphology adjustment by CTAB has good enzyme activity at 15-55°C; at 65°C, CAT only has 17.75% enzyme activity, while ZIF-8-CAT after morphology adjustment by CTAB still maintains 48.79% enzyme activity, so immobilization helps CAT maintain activity.

[0074] The effect of pH on the activity of ZIF-8-CAT was determined by adding 50 μL of 10 mg / mL ZIF-8-CAT solution into a Tris-HCl buffer solution containing 5 mM H2O2, pH 5-10, and the OD 240nm The reaction kinetic curve within 100s was measured at 400 nm. The effect of pH on CAT activity was determined by adding 50 μL of 5 mg / mL CAT solution to a Tris-HCl buffer containing 5 mM H2O2 and pH 5-10. 240nm The reaction kinetics curve within 300s was measured.

[0075] like Figure 9 As shown in Figure b, the enzymatic activities of CAT and ZIF-8-CAT modified with CTAB were highest at pH 7. The activity of ZIF-8-CAT modified with CTAB was more stable than that of CAT between pH 5 and 9. The activity of the immobilized enzyme decreased sharply when the pH exceeded 9. This phenomenon may be due, on the one hand, to the difficulty of CAT in maintaining protein conformational stability in an alkaline environment, and on the other hand, to the susceptibility of ZIF-8-CAT modified with CTAB to decomposition under alkaline conditions.

[0076] (3) Preparation of protective solution: 10 g of a solid mixed powder of ZIF-8, ZIF-8-CAT, and BC was dissolved in 100 mL of deionized water, where the concentrations of ZIF-8, ZIF-8-CAT, and BC were 6 mg / mL, 3.99 mg / mL, and 0.01 mg / mL, respectively.

[0077] Example 2: Inhibitory Effect of the Prepared Protective Solution on Fungi and Bacteria. Method: The fungi and bacteria used in the protective solution were isolated from aged paper. The specific method is as follows: First, a sterile 1x1 cm filter paper was soaked in 10 mg / mL of the protective solution. The fungi and bacteria isolated from the paper were cultured on modified Martin's agar for 12 hours. Then, using an inoculating loop, the fungi and bacteria were dissolved in sterile PBS to form a culture solution. 20 μL of each culture solution was spread on the modified Martin's agar medium. The sterile filter paper soaked in the protective solution was then placed on the surface of the medium. The filter paper was inverted and incubated at 30°C for 3 days. The inhibitory effect of the protective solution on the fungi and bacteria isolated from the aged paper was recorded.

[0078] like Figure 7 As shown, the protective solution prepared by the present invention has a good inhibitory effect on fungi (Penicillium citrinum, Aspergillus, Fusarium) and bacteria (Pseudomonas) isolated from aged paper.

[0079] (4) Preparation of removal solution: Dissolve 2.92 g of EDTA in 1 L of deionized water to prepare a 1 mM removal solution.

[0080] (5) Protective liquid can be effectively used to strengthen and protect aged paper. The method of use is: spray the protective liquid evenly on the surface of the aged paper until the aged paper is completely soaked or soak the aged paper in protective liquid at 20℃ for 5 minutes, then take it out and dry it at 25℃ for 2 days.

[0081] (6) The method of using the removal liquid is as follows: soak the aged paper protected by the protection liquid in the removal liquid for 10 minutes, then take it out and dry it at 25°C for 3 days.

[0082] like Figure 13 As shown, the protective liquid applied on the aged paper is almost completely removed, indicating that the removing liquid has a good removal effect on the protective liquid.

[0083] Example 3

[0084] (1) The green synthesis of ZIF-8 and ZIF-8-CAT was the same as in Example 2;

[0085] (2) Preparation of protective solution: 10 g of ZIF-8, ZIF-8-CAT, and BC solid mixed powder was dissolved in 100 mL of deionized water to obtain a protective solution with a ZIF-8 concentration of 6 mg / mL, a ZIF-8-CAT concentration of 3.9 mg / mL, and a BC concentration of 0.1 mg / mL.

[0086] (3) Preparation of removal solution: Dissolve 0.292 g of EDTA in 1 L of deionized water to make a 1 mM removal solution;

[0087] 1 mg / mL ZIF-8-CAT was placed in 1 mg / mL EDTA solution, and then its OD 207 nm The reaction kinetics curve at the reaction time was calculated, and the effect of reaction time on the degradation rate of ZIF-8-CAT (OD 207nm The larger the absorbance value measured at the position, the faster the degradation rate, and the two are positively correlated). The decomposition product of ZIF-8-CAT, 2-methylimidazole, has an absorption peak at 207nm. Figure 10 As shown in a, as the EDTA concentration in the solution increases, the degradation rate of the protective solution by the removal solution accelerates; Figure 10 As shown in b, the concentration of 2-methylimidazole at 207 nm increased with time (the higher the 2-methylimidazole concentration, the higher the OD 207nm The larger the data measured at the location, the positive correlation between the two) increases linearly, indicating that time has an important influence on the degradation of the protective solution.

[0088] like Figure 11 As shown, when the EDTA concentration is 0 mM, the pH of the removal solution is 6.78, when the EDTA concentration is 0-1 mM, the overall solution is in a neutral to acidic state, when the EDTA concentration is greater than 1 mM, the acidity of the EDTA solution is significantly enhanced, when the EDTA concentration is 1 mM, the pH of the removal solution is 6.5, and the overall solution is in a neutral to acidic state. At this time, ZIF-8-CAT used to remove aged paper can avoid the acid hydrolysis and breakage of aged paper cellulose to the greatest extent.

[0089] (4) Protective liquid can be effectively used to strengthen and protect aged paper. The method of use is: spray the protective liquid evenly on the surface of the aged paper until the aged paper is completely soaked or soak the aged paper in protective liquid at 20℃ for 15 minutes, then take it out and dry it at 25℃ for 3 days.

[0090] (5) The method of using the removal liquid is as follows: immerse the aged paper protected by the protection liquid in the removal liquid, take it out after 20 minutes, and then dry it at 25℃ for 3 days.

[0091] like Figure 14 As shown, the protective liquid applied on the aged paper is almost completely removed, indicating that the removing liquid has a good removal effect on the protective liquid.

Claims

1. A method for preparing a porous material-catalase removable multifunctional protective solution, comprising the following steps: Preparation of ZIF-8: First, dissolve 0.5-2 g of zinc nitrate hexahydrate in 10 mL of deionized water and stir to obtain a zinc nitrate solution. Then, dissolve 15-25 g of 2-methylimidazole in 90 mL of deionized water and stir to obtain a 2-methylimidazole solution. Add 0.04-0.4 g of a surfactant to the 2-methylimidazole solution and stir to obtain a 2-methylimidazole / surfactant mixed solution. Then, quickly add the zinc nitrate solution to the 2-methylimidazole / surfactant mixed solution at room temperature and stir for 5-60 minutes. The solution is then centrifuged for solid-liquid separation. The resulting solid is washed 3-5 times with deionized water to remove unreacted reagents and freeze-dried to obtain ZIF-8. Preparation of ZIF-8-CAT after surfactant-adjusted morphology: First, 0.5-2 g of zinc nitrate hexahydrate was dissolved in 10 mL of deionized water and stirred to obtain a zinc nitrate solution; 15-25 g of 2-methylimidazole was dissolved in 90 mL of deionized water, and then the pH of the solution was adjusted to 9-12 with 5 M HCl and stirred to obtain a 2-methylimidazole solution; 0.04-0.4 g of a surfactant was added to the 2-methylimidazole solution and stirred to obtain a 2-methylimidazole / surfactant mixed solution; then 0.2-1.2 g of CAT was added to the 2-methylimidazole / surfactant mixed solution and stirred vigorously to dissolve it quickly; then the zinc nitrate solution was quickly added to the solution under stirring at room temperature. The mixture was stirred for 5-60 minutes. The solution was then centrifuged for solid-liquid separation. The resulting immobilized product was rinsed with deionized water 3-5 times to remove unreacted reagents. The product was lyophilized to obtain ZIF-8-CAT, the morphology of which was adjusted by a surfactant. CAT is catalase. Preparation of protective solution: 10 g of ZIF-8, ZIF-8-CAT after surfactant-adjusted morphology, and bacterial cellulose were dissolved in 100 mL of deionized water to obtain the porous material-catalase removable multifunctional protective solution; the concentrations of ZIF-8, ZIF-8-CAT after surfactant-adjusted morphology, and bacterial cellulose were 5-10 mg / mL, 1-5 mg / mL, and 0.05-0.1 mg / m, respectively.

2. The method for preparing a porous material-catalase removable multifunctional protective solution according to claim 1, characterized in that: In step (1), the amount of zinc nitrate hexahydrate used is 1-1.5 g, and the amount of 2-methylimidazole used is 18-22 g; the purity of the surfactant is greater than 98%, and the amount thereof used is 0.05-0.2 g; the crystallization stirring time of ZIF-8 is 10-30 min, and the centrifugation time is 10-20 min.

3. The method for preparing a porous material-catalase removable multifunctional protective solution according to claim 1, characterized in that: In step (2), the amount of zinc nitrate hexahydrate used is 1-1.5 g, the amount of 2-methylimidazole used is 18-22 g, and the amount of CAT used is 0.5-1 g; the purity of the surfactant is greater than 98%, and the amount used is 0.05-0.2 g; The crystallization stirring time of ZIF-8-CAT after morphology adjustment by surfactant was 30-40 min; the pH was adjusted to 10-12 using 5 M HCl solution; and the centrifugation time was 10-20 min.

4. The method for preparing a porous material-catalase removable multifunctional protective solution according to claim 1, wherein: In step (3), the concentrations of ZIF-8, ZIF-8-CAT after surfactant-adjusted morphology, and bacterial cellulose are 6-7 mg / mL, 3-4 mg / mL, and 0.05-0.1 mg / mL, respectively; the size of the bacterial cellulose is 150-250 nm.

5. A method for preparing a porous material-catalase removable multifunctional protective solution according to claim 1, characterized in that: The surfactant is cetyltrimethylammonium bromide, bisdecyldimethylammonium chloride or benzalkonium chloride.

6. A porous material-catalase removable multifunctional protective solution, characterized by: The method is prepared by any one of claims 1 to 5.

7. Use of the porous material-catalase removable multifunctional protective solution according to claim 6 in protecting aged paper.

8. Use of the porous material-catalase removable multifunctional protective solution in protecting aged paper according to claim 7, characterized in that: Spray the protective liquid evenly on the surface of the aged paper or immerse the aged paper in the protective liquid at 10~40℃ for 5~30 minutes, then take it out and dry it at 20~40℃ for 2~5 days.

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