Porous chlorine dioxide slow-release fresh-keeping paper and preparation method thereof

Abstract

The application discloses porous chlorine dioxide slow-release preservative paper and a preparation method thereof. The paper comprises a paper base, a porous carrier is fixed on the paper base through oxidized starch glue, sodium chlorite, an activator and a stabilizer are loaded on the porous carrier, and the porous carrier is one of porous structures of aluminum oxide, titanium oxide, cobalt oxide, zinc oxide, copper oxide, iron oxide, cerium oxide, zirconium oxide, nickel oxide, manganese oxide, praseodymium oxide and lanthanum oxide. The application can stably and effectively realize slow release of chlorine dioxide, prolong the release period of chlorine dioxide, and realize long-acting and stable sterilization and disinfection.

Description

Technical Field

[0001] This invention relates to the field of fruit and vegetable preservation technology, and in particular to a porous chlorine dioxide slow-release preservation paper and its preparation method. Background Technology

[0002] ClO2 is a highly efficient and broad-spectrum disinfectant, sterilizer, preservative, and deodorizer. Since the mid-20th century, ClO2 has been used as an antibacterial agent. Its overall performance is the best among commonly used chlorine-based disinfectants, several times higher than typical chlorine-containing disinfectants (chlorine gas, sodium hypochlorite, etc.), and it does not produce carcinogenic or teratogenic organochlorine products after use. It has been rated as an A1-level safe disinfectant by the World Health Organization.

[0003] ClO2, by releasing atomic oxygen with strong oxidizing power, rapidly and effectively inhibits the synthesis of microbial proteins, exhibiting excellent killing effects on bacteria, molds, fungi, viruses, and spores. Chlorine dioxide can quickly and effectively prevent the decomposition of methionine within fruit and vegetable tissues, eliminate substances such as ethylene, and control the growth of spoilage bacteria. It does not react with fatty acids, thus not affecting food quality and delaying the aging and spoilage process of fruits and vegetables. Furthermore, the strong oxidizing properties of chlorine dioxide can oxidize and decompose large-molecule organic pesticides into smaller molecules, converting toxic substances into harmless ones, ensuring the safety and hygiene of fruits. However, ClO2 gas is unstable, easily decomposes upon exposure to light, and has poor stability, generally making it inconvenient to prepare concentrated solutions, thus hindering its use as a fruit and vegetable preservative and resulting in poor effectiveness.

[0004] ClO2 preservation paper, as a slow-release preservation technology, does not directly contact the product, is convenient and controllable, environmentally friendly, and safe. It can effectively preserve fruits and vegetables and is currently widely used in fruit and vegetable preservation. ClO2 preservation paper is made by bonding a paper base containing a ClO2 precursor, such as sodium chlorite, to a paper base containing a weak acid. The chemical reaction between sodium chlorite and the hydrogen ions in the weak acid produces chlorine dioxide, giving it stronger oxidizing and bactericidal capabilities. However, ClO2 preservation paper is prone to ClO2 burst release and short retention time during preparation and use, resulting in poor ClO2 preservation effects. Therefore, solving the problems of ClO2 burst release and short retention time in ClO2 preservation paper, and utilizing ClO2 preservation paper for post-harvest fruit preservation to reduce post-harvest softening, rotting, and spoilage, thereby improving fruit quality, are urgent technical problems that the preservation industry needs to address.

[0005] Two aspects need to be considered in the preparation of food preservation paper base: 1. Sodium chlorite is a precursor to ClO2 release. Its effective content in the preservation paper reflects its potential for releasing ClO2 gas. Because sodium chlorite has strong oxidizing properties, it is easily affected by reducing components in the environment and loses its activity. Therefore, the loading rate of sodium chlorite must be considered in the structural design of the preservation paper, making it an important indicator in the experiment. 2. ClO2 is the main component responsible for preservation. The concentration of ClO2 in the fruit and vegetable storage environment can regulate the atmosphere and microbial levels in the fruit and vegetable microenvironment. Controlling its release pattern is an important part of the preparation of food preservation paper. During the preparation of the preservation paper, it is necessary to control indicators such as the maximum release rate of ClO2, the time of occurrence of the maximum rate, and the total amount of ClO2 released to ensure that the preservation system has the optimal amount of ClO2 released.

[0006] Existing chlorine dioxide slow-release preservation paper technology achieves the slow release of ClO2 through a wood fiber substrate + oxidized starch adhesive embedding + double paper base lamination design, as shown in CN104480792A. Specifically, it uses wood residues (such as branches, bark, sawdust) as raw materials, which are boiled in NaOH solution, washed with water until neutral, milled in a disc mill, and then processed into soft fibers. Finally, it is paper-made into two types of paper bases, A and B. The loading of preservatives and activators is as follows: Preservative system: Paper base A: coated with an oxidized starch adhesive solution containing sodium chlorite (NaClO2). Activator: Paper base B: coated with tartaric acid solution. Lamination design: After the A and B paper bases are laminated, the CO2 produced by the respiration of fruits and vegetables reacts with water to form carbonic acid. Free H⁺ activates tartaric acid, thereby promoting the conversion of NaClO2 into ClO2, achieving slow release. The chemical reaction formula is as follows:

[0007] .

[0008] The above method has the following problems:

[0009] Stability issues: NaClO2 is prone to decomposition when humidity is >5%, and its loading capacity is difficult to increase.

[0010] Too short a release time: Due to the intensity of fruit respiration and the difficulty in controlling moisture in the air, chlorine dioxide is prone to explosive release, causing it to become ineffective in a short time. Summary of the Invention

[0011] The purpose of this invention is to provide a porous chlorine dioxide slow-release preservation paper and its preparation method, which can stably and effectively achieve the slow release of chlorine dioxide, extend the release period of chlorine dioxide, and provide a long-lasting and stable bactericidal and disinfecting effect.

[0012] The technical solution adopted by this invention to solve its technical problem is:

[0013] A method for preparing porous chlorine dioxide slow-release preservation paper includes the following steps:

[0014] I. Preparation of porous precursors with activator embedding

[0015] (1) Mix the surfactant and organic solvent evenly at a ratio of 1g: 5-20mL to obtain solution A;

[0016] (2) Mix the organic acid with solution A until homogeneous to obtain solution B;

[0017] (3) Add the metal salt and activator to solution B, mix them evenly, and obtain a porous precursor embedded with activator after high-temperature reaction and calcination;

[0018] II. Preparation of porous carriers with composite sodium chlorite:

[0019] (4) Stir and mix the stabilizer with deionized water to disperse it evenly and obtain an impregnation solution; add the porous precursor embedded with the activator into the impregnation solution, stir and impregnate for 1-24 h, and then dry and calcine to obtain the porous precursor of the composite stabilizer.

[0020] (5) Add the porous precursor of the composite stabilizer to a sodium chlorite solution with a concentration of 0.05-0.5 g / mL, stir and soak for 1-24 h, and then dry to obtain the porous carrier of the composite sodium chlorite.

[0021] In step (5), experiments showed that the soaking time has a great influence on the sodium chlorite loading. If the time is too short, the sodium chlorite adsorption is low, and if the time is too long, the decomposition of sodium chlorite increases.

[0022] III. Preparation of slow-release preservative paper:

[0023] (6) Mix the porous carrier of composite sodium chlorite and oxidized starch glue, stir and mix in a water bath at 40-50℃ to form a coating liquid;

[0024] (7) After cutting the paper base, place it in a desiccator to remove moisture, and then evenly coat the paper base with the coating liquid. The coating amount is 0.5~5 mg / cm². 2 Porous chlorine dioxide slow-release preservation paper was obtained.

[0025] The porous carrier prepared by the method of the present invention has a regular and orderly morphology, stable structure, high sodium chlorite loading, and fully exposed active sites of heteropolyacid (activator), making the effect of heteropolyacid-sodium chlorite more obvious and promoting the release of chlorine dioxide. At the same time, the stabilizer is uniformly dispersed in the carrier, and the release rate of chlorine dioxide can be controlled by adjusting the amount added.

[0026] The surfactant is selected from block copolymer nonionic surfactants; specifically, block copolymer nonionic surfactants can be selected from F127, P123, PEI (polyethyleneimine), etc.

[0027] The organic solvent is selected from one or more of methanol, ethanol, n-butanol, and acetonitrile;

[0028] The organic acid is citric acid or ascorbic acid; both citric acid and ascorbic acid have good synthetic effects.

[0029] The activator is selected from one or more of silicotungstic acid, phosphotungstic acid, ammonium molybdate, and tartaric acid.

[0030] The metal salt is a salt formed from one of aluminum, titanium, cobalt, zinc, copper, iron, cerium, zirconium, nickel, manganese, praseodymium, and lanthanum, and the salt is a nitrate, acetate, or chlorate.

[0031] The mass ratio of the surfactant, activator, metal salt, and organic acid is 1:0.01~0.5:0.5~5:0.1~1. Within this range, the product morphology is regular and the activator is dispersed. Preferably, the mass ratio of the surfactant, activator, metal salt, and organic acid is 1:0.2~0.4:1~2:0.1~1.

[0032] In step (3), the high-temperature reaction temperature is 100-150℃, and the time is 1-72 h; in steps (3) and (4), the calcination temperature is 300-700℃, and the time is 1-20 h. The reaction temperature has a crucial influence on the morphology of the product. If the temperature is too high, the activator will aggregate; if the temperature is too low, the product self-assembly process cannot occur. The calcination temperature has an important influence on the morphology and pore structure of the product. If the temperature is too low, the organic matter inside the product cannot be removed; if the temperature is too high, the internal pores of the product will collapse. Preferably, the high-temperature reaction temperature is 110-130℃, and the time is 10-24 hours; the calcination temperature is 300-500℃, and the time is 2-6 h.

[0033] In steps (4) and (5), the drying parameters are: drying temperature 60-100℃, and drying time 1-20 h. The preferred drying time is 10-15 h.

[0034] In step (4), the stabilizer is one or a combination of two of silica, gelatin and starch, and the mass ratio of the stabilizer to the porous precursor embedded with the activator is 1:1-20.

[0035] In step (5), the mass ratio of sodium chlorite to the porous precursor of the composite stabilizer is 1:5-20.

[0036] In step (6), the mass ratio of oxidized starch adhesive to porous carrier of composite sodium chlorite is 10:1-5.

[0037] A porous chlorine dioxide slow-release preservation paper prepared by the aforementioned preparation method comprises a paper base, on which a porous carrier is fixed by oxidized starch adhesive. The porous carrier is loaded with sodium chlorite, an activator, and a stabilizer. The porous carrier is one of the following porous materials: alumina, titanium dioxide, cobalt oxide, zinc oxide, copper oxide, iron oxide, cerium oxide, zirconium oxide, nickel oxide, manganese oxide, praseodymium oxide, and lanthanum oxide.

[0038] The oxidized starch adhesive is prepared by using corn starch as raw material and an oxidizing agent oxidation method. The oxidizing agent is potassium permanganate or hydrogen peroxide. Specifically, distilled water, corn starch, sodium hydroxide, and potassium permanganate are mixed in a mass ratio of 100:5-20:0.1-1:1-5 in a three-necked flask and heated and stirred in a water bath at 80-100℃ for 30 minutes to obtain the oxidized starch adhesive.

[0039] Another technical problem this invention aims to solve is maintaining the long-term release of chlorine dioxide. Experiments have shown that the synthesis temperature of the porous carrier, the type and amount of surfactant added, the calcination temperature, and the type and amount of solvent added can control the pore size and specific surface area of ​​the prepared carrier. The pore size and specific surface area of ​​the porous carrier directly affect the loading of sodium chlorite. The amount of stabilizer added and the type of porous carrier are closely related to the sustained release rate of chlorine dioxide.

[0040] The porous carrier has a specific surface area of ​​10 to 1000 m². 2 / g;

[0041] The porous carrier has a pore size of 1 to 100 nm.

[0042] The beneficial effects of this invention are:

[0043] 1. Single-sheet paper-based structure, no AB paper-based bonding required; simply seal and store before use. When using, open the seal; the release of chlorine dioxide is triggered by moisture in the air and evaporation from the fruit. Furthermore, all reagents used in the preparation process are easily recyclable and will not cause environmental pollution.

[0044] 2. The porous carrier structure increases the specific surface area and improves the loading capacity of sodium chlorite, with the highest loading capacity of sodium chlorite exceeding 20%.

[0045] 3. The porous structure facilitates the single dispersion of the activator, heteroacids, ensuring a stable release rate of chlorine dioxide and effectively preventing explosive release. The effective sustained release time of chlorine dioxide exceeds 6 months.

[0046] 4. Fruit preservation test: Blueberries can be kept fresh at room temperature for more than 30 days. Attached Figure Description

[0047] Figure 1 This is a SEM image of the porous honeycomb cobalt tetroxide material with activator embedded in Example 1;

[0048] Figure 2 This is a graph showing the relationship between chlorine dioxide release and time.

[0049] Figure 3 This is a diagram of a blueberry preservation experiment. Detailed Implementation

[0050] The technical solution of the present invention will be further described in detail below through specific embodiments.

[0051] In this invention, unless otherwise specified, all raw materials and equipment used are commercially available or commonly used in the field. The methods described in the following embodiments are conventional methods in the field, unless otherwise specified.

[0052] Example 1 of preparation of oxidized starch gum:

[0053] Distilled water, corn starch, sodium hydroxide, and potassium permanganate were mixed in a mass ratio of 100:10:0.5:2 in a three-necked flask and heated and stirred in a 90°C water bath for 30 minutes to obtain oxidized starch gel.

[0054] Example 2 of preparation of oxidized starch gum:

[0055] Distilled water, corn starch, sodium hydroxide, and potassium permanganate were mixed in a mass ratio of 100:5:0.1:1 in a three-necked flask and heated and stirred in an 80°C water bath for 30 minutes to obtain oxidized starch gel.

[0056] Example 3 of preparation of oxidized starch gum:

[0057] Distilled water, corn starch, sodium hydroxide, and potassium permanganate were mixed in a mass ratio of 100:20:1:5 in a three-necked flask and heated and stirred in a water bath at 100°C for 30 minutes to obtain oxidized starch gel.

[0058] Example 1:

[0059] 3g of surfactant PEI was dissolved in 30 mL of n-butanol and stirred until homogeneous. Then, 0.4g of citric acid (CA) was added and stirred until homogeneous. Subsequently, 2g of cobalt nitrate tetrahydrate was added and stirred until uniformly dispersed. Finally, 0.3g of ammonium molybdate was added and stirred until homogeneous. The solution was transferred to a petri dish and reacted for 10 h at 120 °C. The reaction product was then transferred to a muffle furnace and calcined at 350 °C for 4 h. A porous honeycomb cobalt tetroxide material with activator embedded was prepared.

[0060] 1g of gelatin was dispersed in 50 mL of deionized water to obtain a dispersion. The above-mentioned 3g of activator-embedded hierarchical porous cobalt tetroxide material was added to the dispersion and stirred and soaked for 4 hours. Then the mixture was dried in an oven at 100℃ for 10 hours. Finally, it was calcined in a muffle furnace at 350℃ for 2 hours to obtain a porous precursor of the composite stabilizer.

[0061] 4g of the porous precursor of the above composite stabilizer was dispersed in 50 mL of deionized water to obtain a dispersion; 0.8g of sodium chlorite was weighed and mixed with 10 mL of deionized water to obtain an oxidant impregnation solution; the dispersion and the oxidant impregnation solution were mixed evenly, stirred and impregnated for 8 hours, and dried at 100℃ for 10 hours to obtain a porous carrier of composite sodium chlorite.

[0062] Take 0.1g of a porous carrier containing sodium chlorite, add 1g of oxidized starch adhesive (prepared in Example 1 of oxidized starch adhesive preparation), and mix and stir in a water bath at 45℃ for 30 min to obtain a coating solution. Apply 50mg of the coating solution evenly to a 10*10cm paper substrate. This yields a chlorine dioxide slow-release preservation paper.

[0063] Blueberries of uniform size, similar color, consistent maturity, and free from mechanical damage, pests, diseases, and rot were selected. After harvesting, the blueberries were placed at 20 ℃ for 4 hours to dissipate field heat and then evenly divided into three groups of 15 blueberries each. Group A: Control group (no paper base); Group B: Blank paper base (10*10cm); Group C: 10*10cm chlorine dioxide slow-release preservation paper base (prepared in Example 1); Group D (conventional A+B composite paper base group): 0.1g of porous carrier containing composite sodium chlorite (without the activator ammonium molybdate) was added to 1g of oxidized starch adhesive (prepared in Example 1 of oxidized starch adhesive preparation), and the mixture was stirred in a water bath at 45 ℃ for 30 min to obtain a coating solution. 50mg of the coating solution was evenly applied to a 10*10cm A paper base (10g in weight); 0.3g of ammonium molybdate was added to 1g of oxidized starch adhesive (prepared in Example 1 of oxidized starch adhesive preparation), and the mixture was stirred in a water bath at 45 ℃ for 30 min to obtain a coating solution. Apply 50mg of the coating solution evenly to a 10*10cm B-type paper base. Store separately, but attach together when using. Store in a sealed container at room temperature.

[0064] Figure 1The image shows a SEM image of the porous honeycomb cobalt tetroxide material embedded with the activator prepared in Example 1. It was observed that the material has a porous honeycomb structure.

[0065] Figure 2 This is a graph showing the relationship between chlorine dioxide release and time. The graph shows that the release rate of chlorine dioxide is very stable, and there is no explosive release phenomenon.

[0066] Figure 3 This is a diagram of a blueberry preservation experiment. From top to bottom, the first row shows the results for day 0, the second row for day 3, the third row for day 7, and the fourth row for day 27. On day 0 (the day itself), the rot rate of blueberries in groups AD was 0%; on day 3, the rot rate of blueberries in groups A and CD was 0%, while the rot rate of blueberries in group B was approximately 7%; on day 7, the rot rate of blueberries in group A was approximately 7%, the rot rate of blueberries in group B was approximately 15%, and the rot rate of blueberries in groups CD was 0%; on day 27, the rot rate of blueberries in groups AB was 100%, and the rot rate of blueberries in groups CD remained 0%. From the diagram, we can clearly see that chlorine dioxide preservation paper effectively maintains the freshness of blueberries, significantly reduces the rot rate, and extends the shelf life.

[0067] Example 2: 2.5 g of surfactant P123 was dissolved in 30 mL of methanol and stirred until homogeneous. Then, 0.37 g of CA was added and stirred until homogeneous. Subsequently, 2.1 g of cobalt nitrate tetrahydrate was added and stirred until uniformly dispersed. Finally, 0.3 g of ammonium molybdate was added and stirred until homogeneous. The above solution was transferred to a petri dish and reacted for 10 h at 120 °C. The reaction product was then transferred to a muffle furnace and calcined at 350 °C for 4 h. A mesoporous honeycomb cobalt tetroxide material with activator embedded was prepared.

[0068] 1g of gelatin was dispersed in 50 mL of deionized water to obtain a dispersion. The above 3g of activator-embedded hierarchical honeycomb cobalt tetroxide material was added to the dispersion and stirred for 4 hours. The mixture was then dried in an oven at 100 ℃ for 10 hours. Finally, it was calcined in a muffle furnace at 350 ℃ for 2 hours to obtain a porous precursor of the composite stabilizer.

[0069] 4g of the porous precursor of the above composite stabilizer was dispersed in 50 mL of deionized water to obtain a dispersion; 0.8g of sodium chlorite was weighed and mixed with 10 mL of deionized water to obtain an oxidant impregnation solution; the dispersion and the oxidant impregnation solution were mixed evenly, stirred and impregnated for 8 hours, and dried at 100 °C for 10 hours to obtain a porous carrier of composite sodium chlorite.

[0070] Take 0.2g of the porous carrier containing composite sodium chlorite, add 0.5g of oxidized starch adhesive (prepared in Example 1 of oxidized starch adhesive preparation), and mix and stir in a water bath at 45℃ for 30min to obtain a coating solution. Apply 50mg of the coating solution evenly to a 10*10cm paper substrate to obtain chlorine dioxide slow-release preservation paper.

[0071] Example 3:

[0072] 3g of surfactant PEI was dissolved in 30 mL of n-butanol and stirred until homogeneous. Then, 0.4g of CA was added and stirred until homogeneous. Subsequently, 3g of aluminum nitrate hexahydrate was added and stirred until uniformly dispersed. Finally, 0.3g of phosphotungstic acid was added and stirred until homogeneous. The above solution was transferred to a petri dish and reacted for 10 h at 120 ℃. The reaction product was then transferred to a muffle furnace and calcined at 350 ℃ for 4 h. A porous alumina material with activator embedded was prepared.

[0073] 1g of nano-silica was dispersed in 50 mL of deionized water to obtain a dispersion. The porous alumina material embedded with the above-mentioned 3g activator was added to the dispersion and stirred and soaked for 4 hours. Then the mixture was dried in an oven at 100℃ for 10 hours. Finally, it was calcined in a muffle furnace at 350℃ for 2 hours to obtain a porous precursor of the composite stabilizer.

[0074] 4g of the porous precursor of the above composite stabilizer was dispersed in 50 mL of deionized water to obtain a dispersion; 0.8g of sodium chlorite was weighed and mixed with 10 mL of deionized water to obtain an oxidant impregnation solution; the dispersion and oxidant impregnation solution were mixed evenly, stirred and impregnated for 8 hours, and dried at 100 °C for 10 hours to obtain the composite precursor.

[0075] Take 0.2g of a porous carrier containing sodium chlorite and add 0.5g of oxidized starch adhesive (prepared in Example 1 of oxidized starch adhesive preparation). Mix and stir in a water bath at 45℃ for 30 min to obtain a coating solution. Apply 50mg of the coating solution evenly to a 10*10cm paper substrate. This yields a chlorine dioxide slow-release preservation paper.

[0076] Example 4

[0077] 3g of surfactant F127 was dissolved in 15 mL of acetonitrile and stirred until homogeneous. Then, 0.3g of ascorbic acid was added and stirred until homogeneous. Subsequently, 1.5g of lanthanum nitrate was added and stirred until uniformly dispersed. Finally, 0.03g of tartaric acid was added and stirred until homogeneous. The above solution was transferred to a petri dish and reacted for 24 h at 110℃. The reaction product was then transferred to a muffle furnace and calcined at 300℃ for 6 h. A porous honeycomb lanthanum oxide material with activator embedded was prepared.

[0078] 1g of gelatin was dispersed in 50 mL of deionized water to obtain a dispersion. The above 1g of activator-embedded hierarchical porous honeycomb lanthanum oxide material was added to the dispersion and stirred and impregnated for 1 hour. The mixture was then dried in an oven at 60°C for 15 hours. Finally, it was calcined in a muffle furnace at 300°C for 6 hours to obtain a porous precursor of the composite stabilizer.

[0079] Take 5g of the porous precursor of the above composite stabilizer and disperse it in 50 mL of deionized water to obtain a dispersion; weigh 0.5g of sodium chlorite and mix it with 10 mL of deionized water to obtain an oxidant impregnation solution; mix the dispersion and the oxidant impregnation solution evenly, stir and impregnate for 1 h, and dry at 60℃ for 15 h to obtain a porous carrier of composite sodium chlorite.

[0080] Take 0.2g of the porous carrier containing composite sodium chlorite, add 1g of oxidized starch adhesive (prepared in Example 1 of oxidized starch adhesive preparation), and mix and stir in a water bath at 40℃ for 30 min to obtain a coating solution. Apply 500mg of the coating solution evenly to a 10*10cm paper substrate. This yields chlorine dioxide slow-release preservation paper.

[0081] Example 5

[0082] 3g of surfactant P123 was dissolved in 60 mL of ethanol and stirred until homogeneous. Then, 3g of CA was added and stirred until homogeneous. Subsequently, 15g of praseodymium acetate was added and stirred until uniformly dispersed. Finally, 1.5g of silicotungstic acid was added and stirred until homogeneous. The above solution was transferred to a petri dish and reacted for 10 h at 130℃. The reaction product was then transferred to a muffle furnace and calcined at 500℃ for 2 h. A porous honeycomb praseodymium oxide material with activator embedded was prepared.

[0083] 1g of gelatin was dispersed in 100 mL of deionized water to obtain a dispersion. 20g of the above-mentioned activator-embedded hierarchical honeycomb praseodymium oxide material was added to the dispersion and stirred and soaked for 24h. The mixture was then dried in an 80℃ oven for 12h. Finally, it was calcined in a muffle furnace at 500℃ for 2h to obtain a porous precursor of the composite stabilizer.

[0084] 100g of the porous precursor of the above composite stabilizer was dispersed in 300 mL of deionized water to obtain a dispersion; 5g of sodium chlorite was weighed and mixed with 10 mL of deionized water to obtain an oxidant impregnation solution; the dispersion and the oxidant impregnation solution were mixed evenly, stirred and impregnated for 24 h, and dried at 80℃ for 12 h to obtain a porous carrier of composite sodium chlorite.

[0085] Take 0.5g of a porous carrier containing composite sodium chlorite, add 2.5g of oxidized starch adhesive (prepared in Example 1 of oxidized starch adhesive preparation), and mix and stir in a water bath at 50℃ for 30 min to obtain a coating solution. Apply 100mg of the coating solution evenly onto a 10*10cm paper substrate. This yields a chlorine dioxide slow-release preservation paper.

[0086] Example 6

[0087] Take 5g of the porous precursor of the composite stabilizer prepared in Example 1 and disperse it in 50mL of deionized water to obtain a dispersion; weigh 1g of sodium chlorite and mix it with 10mL of deionized water to obtain an oxidant impregnation solution; mix the dispersion and the oxidant impregnation solution evenly, stir and impregnate for 8h, and dry at 100℃ for 12h to obtain a porous carrier of composite sodium chlorite.

[0088] Comparative Example 1

[0089] Add 1g of sodium chlorite to 20ml of water and stir until completely dissolved to prepare solution A; take 5g of activated carbon and disperse it in 20ml of water to prepare solution B; quickly pour solution A into solution B, stir for 8 hours, and dry at 100℃ for 12 hours to obtain activated carbon-supported sodium chlorite.

[0090] Comparative Example 2

[0091] Using the same method as Comparative Example 1, the support was replaced with 4A molecular sieve.

[0092] Comparative Example 3

[0093] Using the same method as Comparative Example 1, the carrier was replaced with a 1:1 mass ratio mixture of activated carbon and 4A molecular sieve.

[0094] The sustained-release effects of Example 6 and Comparative Examples 1-3 were determined in an open environment at room temperature. The sodium chlorite loading rate refers to the percentage of sodium chlorite weight to the weight of the carrier. The specific results are as follows:

[0095] .

[0096] The comparison shows that, compared with conventional porous carriers, the carrier of the present invention has the highest sodium chlorite loading and the best sustained-release effect.

[0097] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Other variations and modifications are possible without departing from the technical solutions described in the claims.

Claims

1. A method for preparing porous chlorine dioxide slow-release preservative paper, characterized in that, Includes the following steps: I. Preparation of porous precursors with activator embedding (1) Mix the surfactant and organic solvent evenly at a ratio of 1g: 5-20mL to obtain solution A; (2) Mix the organic acid with solution A until homogeneous to obtain solution B; (3) Add the metal salt and activator to solution B, mix them evenly, and obtain a porous precursor embedded with activator after high-temperature reaction and calcination; II. Preparation of porous carriers with composite sodium chlorite: (4) Stir and mix the stabilizer with deionized water to disperse it evenly and obtain an impregnation solution; add the porous precursor embedded with the activator into the impregnation solution, stir and impregnate for 1-24 h, and then dry and calcine to obtain the porous precursor of the composite stabilizer. (5) Add the porous precursor of the composite stabilizer to a sodium chlorite solution with a concentration of 0.05-0.5 g / mL, stir and soak for 1-24 h, and then dry to obtain the porous carrier of the composite sodium chlorite. III. Preparation of slow-release preservative paper: (6) Mix the porous carrier of composite sodium chlorite and oxidized starch glue, stir and mix in a water bath at 40-50℃ to form a coating liquid; (7) After cutting the paper base, place it in a desiccator to remove moisture, and then evenly coat the paper base with the coating liquid. The coating amount is 0.5~5 mg / cm². 2 Porous chlorine dioxide slow-release preservation paper was obtained; The surfactant is selected from block copolymer nonionic surfactants; The organic solvent is selected from one or more of methanol, ethanol, n-butanol, and acetonitrile; The organic acid is citric acid or ascorbic acid; The activator is selected from one or more of silicotungstic acid, phosphotungstic acid, and ammonium molybdate; The metal salt is a salt formed from one of aluminum, titanium, cobalt, zinc, copper, iron, cerium, zirconium, nickel, manganese, praseodymium, and lanthanum, and the salt is a nitrate, acetate, or chlorate. In step (4), the stabilizer is one or a combination of two of silica, gelatin, and starch, and the mass ratio of the stabilizer to the porous precursor embedded with the activator is 1:1-20. The mass ratio of the surfactant, activator, metal salt and organic acid is 1:0.01~0.5:0.5~5:0.1~1.

2. The preparation method according to claim 1, characterized in that, In step (3), the reaction temperature of the high-temperature reaction is 100-150℃ and the time is 1-72 h; in steps (3) and (4), the calcination temperature is 300-700℃ and the time is 1-20 h.

3. The preparation method according to claim 1, characterized in that, In steps (4) and (5), the drying parameters are: drying temperature 60-100℃, and time 1-20 h.

4. The preparation method according to claim 1, characterized in that, In step (5), the mass ratio of sodium chlorite to the porous precursor of the composite stabilizer is 1:5-20.

5. The preparation method according to claim 1, characterized in that, In step (6), the mass ratio of oxidized starch adhesive to porous carrier of composite sodium chlorite is 10:1-5.

6. A porous chlorine dioxide slow-release preservation paper prepared by the preparation method of claim 1, comprising a paper base, characterized in that, A porous carrier is fixed on the paper base by oxidized starch adhesive. Sodium chlorite, activator and stabilizer are loaded on the porous carrier. The porous carrier is one of the following porous materials: alumina, titanium oxide, cobalt oxide, zinc oxide, copper oxide, iron oxide, cerium oxide, zirconium oxide, nickel oxide, manganese oxide, praseodymium oxide and lanthanum oxide.

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