Porous chlorine dioxide slow-release preservative paper and preparation method thereof

Abstract

The invention discloses porous chlorine dioxide slow-release preservative paper and a preparation method thereof.The porous chlorine dioxide slow-release preservative paper comprises a paper base, a porous carrier is fixed to the paper base through oxidized starch glue, and sodium chlorite, an activating agent and a stabilizing agent are loaded on the porous carrier; the porous carrier is one 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 with a porous structure. The slow release of chlorine dioxide can be stably and effectively realized, the release period of chlorine dioxide is prolonged, and long-acting stable sterilization and disinfection effects are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fruit and vegetable preservation, and particularly relates to a porous chlorine dioxide slow-release preservation paper and a preparation method thereof. BACKGROUND

[0002] ClO2 is a high-efficiency, broad-spectrum disinfectant, preservative and deodorant. Since the mid-20th century, ClO2 has been used as an antibacterial agent. Its comprehensive performance is the best among the currently used chlorine-based disinfectants, several times higher than that of general chlorine-containing disinfectants (chlorine, sodium hypochlorite, etc.), and no carcinogenic and teratogenic organic chlorine products are generated after use, and it has been rated as an A1-level safe disinfectant by the World Health Organization.

[0003] ClO2 can quickly and effectively inhibit the synthesis of microbial proteins by releasing atomic oxygen with strong oxidizing ability, and has good killing effect on bacteria, molds, fungi, viruses and spores. Chlorine dioxide can quickly and effectively prevent the decomposition of methionine in fruit and vegetable tissues, eliminate ethylene and other substances, and control the growth of spoilage bacteria, without affecting the quality of food, thereby delaying the aging and spoilage process of fruits and vegetables. In addition, the strong oxidizing property of chlorine dioxide can also oxidize and decompose large molecular organic pesticides into small molecules, and convert toxic substances into harmless substances to ensure the safety and health of fruits. However, ClO2 gas is not stable and decomposes easily in the light, and has poor stability, so it is generally not convenient to prepare concentrated solutions, which makes it inconvenient and ineffective in fruit and vegetable preservation.

[0004] ClO2 preservation paper, as a slow-release preservation technology, does not directly contact with the product, is convenient and controllable, green and environmentally friendly, and safe, and can play a role in preserving fruits and vegetables. At present, it is more commonly used in fruit and vegetable preservation. ClO2 preservation paper is obtained by bonding a paper base containing a ClO2 precursor such as sodium chlorite and a paper base containing a weak acid together, and generating chlorine dioxide by chemical reaction of sodium chlorite and hydrogen ions in the weak acid, so as to have stronger oxidizing property and bactericidal capacity. However, ClO2 preservation paper is prone to ClO2 burst release and short storage time during preparation and use, resulting in poor ClO2 preservation effect. Therefore, solving the problems of burst release and short storage time in ClO2 preservation paper, and using ClO2 preservation paper to preserve fruits after harvesting, thereby reducing the phenomenon of softening, rotting and deterioration of fruits after harvesting, and improving the quality of fruits are technical problems that need to be solved in the preservation industry.

[0005] The paper base of the preservative paper needs to consider two aspects: 1. Sodium chlorite is a precursor of ClO2 release, and the effective content of sodium chlorite in the preservative paper reflects the potential of the preservative paper to release ClO2 gas. Since sodium chlorite has strong oxidizing property, it is easily affected by reducing components in the environment and loses activity. Therefore, the loading rate of sodium chlorite needs to be considered in the structural design of the preservative paper. Therefore, it is taken as an important index in the experiment. 2. ClO2 is the main component for preservation, and the concentration of ClO2 in the fruit and vegetable storage environment can adjust the atmosphere and microbial level in the microenvironment. Controlling the release law is an important part of the preparation process of the preservative paper. In the preparation process of the preservative paper, the maximum release rate of ClO2, the time of the maximum release rate, the total amount of ClO2 release and other indicators need to be controlled to ensure that the preservative system can have the best ClO2 release amount.

[0006] The existing chlorine dioxide slow-release preservative paper technology realizes the slow release of ClO2 through wood fiber base material + oxidized starch glue embedding + double paper base design, such as CN104480792A. Specifically, wood residues (such as branches, bark, sawdust) are used as raw materials, which are cooked by NaOH solution, washed to neutral, refined by a disc refiner, then treated by beating to form soft fibers, and finally beaten into A and B two kinds of paper bases. The loading of preservative and activator: preservative system: A paper base: coated with oxidized starch glue containing sodium chlorite (NaClO2). Activator: B paper base: coated with tartaric acid solution. Design of sticking: after sticking A and B paper bases, CO2 produced by fruit and vegetable respiration and water form carbonic acid, free H⁺ activates tartaric acid, and then promotes NaClO2 to ClO2, realizing slow release. The chemical reaction formula is as follows: .

[0007] The above method has the following problems: Stability problem: NaClO2 is easy to decompose when the humidity is >5%, and its loading amount is difficult to improve.

[0008] Slow release time is too short: due to the strong respiration intensity of fruits and the difficulty in controlling the moisture in the air, chlorine dioxide is prone to burst release, resulting in failure in a short time. SUMMARY

[0009] The purpose of the present application is to provide a porous chlorine dioxide slow-release preservative paper and a preparation method thereof, which can stably and effectively realize the slow release of chlorine dioxide, prolong the release period of chlorine dioxide, and realize the long-acting and stable sterilization and disinfection effect.

[0010] The technical scheme adopted by the present application to solve the technical problems is: A preparation method of a porous chlorine dioxide slow-release preservative paper, comprising the following steps: I. Preparation of activated agent inlaid porous precursor (1) the surfactant and organic solvent are mixed uniformly according to a ratio of 1g:5-20mL to obtain solution A; (2) the organic acid is mixed uniformly with solution A to obtain solution B; (3) the metal salt and activator are added to solution B, mixed uniformly, and after high-temperature reaction and calcination, the activated agent-embedded porous precursor is obtained; II. Preparation of the porous carrier loaded with sodium chlorite: (4) the stabilizer is mixed with deionized water by stirring to disperse uniformly to obtain an impregnation solution; the activated agent-embedded porous precursor is added to the impregnation solution, stirred and impregnated for 1-24h, and after drying and calcination, the porous precursor loaded with the stabilizer is obtained; (5) the porous precursor loaded with the stabilizer is added to a sodium chlorite solution with a concentration of 0.05-0.5g / mL, stirred and impregnated for 1-24h, and after drying, the porous carrier loaded with sodium chlorite is obtained; In step (5), it is found through experiments that the impregnation time has a great influence on the loading amount of sodium chlorite; if the time is too short, the adsorption amount of sodium chlorite is low, and if the time is too long, the decomposition of sodium chlorite increases.

[0011] III. Preparation of the slow-release fresh-keeping paper: (6) the porous carrier loaded with sodium chlorite and the oxidized starch glue are mixed, and stirred uniformly in a water bath at 40-50℃ to form a coating liquid; (7) the paper base is cut and placed in a dryer to remove water, and then the coating liquid is uniformly coated on the paper base, and the coating amount is 0.5-5mg / cm 2 , to obtain the porous chlorine dioxide slow-release fresh-keeping paper.

[0012] The porous carrier prepared by the preparation method has a regular and ordered morphology, a stable structure, a high loading amount of sodium chlorite, and active sites of the heteropoly acid (activator) fully exposed, so that the effect of the heteropoly acid-sodium chlorite becomes more obvious, and the release of chlorine dioxide is promoted; meanwhile, the stabilizer is uniformly dispersed in the carrier, and by adjusting the added amount, the release speed of chlorine dioxide can be controlled.

[0013] The surfactant is selected from block copolymer nonionic surfactants; the block copolymer nonionic surfactant can be specifically selected from F127, P123, PEI (polyethyleneimine), etc.

[0014] 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; both citric acid and ascorbic acid have good synthesis effects.

[0015] The activator is selected from one or more of silicotungstic acid, phosphotungstic acid, ammonium molybdate, and tartaric acid.

[0016] The metal salt is a salt of one of aluminum, titanium, cobalt, zinc, copper, iron, cerium, zirconium, nickel, manganese, praseodymium, lanthanum, and the salt is a nitrate, acetate, chlorate.

[0017] The mass ratio of the surfactant, activator, metal salt, and organic acid is 1:0.01-0.5:0.5-5:0.1-1. In this ratio range, the product morphology is regular, and the activator is in a dispersed state. Preferably, the mass ratio of the surfactant, activator, metal salt, and organic acid is 1:0.2-0.4:1-2:0.1-1.

[0018] In step (3), the high-temperature reaction temperature is 100-150°C, and the time is 1-72 h; in steps (3) and (4), the calcination temperature is 300-700°C, and the time is 1-20 h. The reaction temperature has a key influence on the product morphology, and a temperature that is too high causes the activator to aggregate, and a temperature that is too low causes the self-assembly process of the product to fail to occur. The calcination temperature has an important influence on the product morphology and pore structure, and a temperature that is too low causes the internal organic matter of the product to fail to be removed, and a temperature that is too high causes the internal pores of the product to collapse. Preferably, the high-temperature reaction temperature is 110-130°C, and the time is 10-24 h; the calcination temperature is 300-500°C, and the time is 2-6 h.

[0019] In steps (4) and (5), the drying parameters are: a drying temperature of 60-100°C, and a time of 1-20 h. The drying time is preferably 10-15 h.

[0020] In step (4), the stabilizer is one or a combination of two of silicon dioxide, gelatin, and starch, and the mass ratio of the stabilizer to the porous precursor in which the activator is embedded is 1:1-20.

[0021] In step (5), the mass ratio of sodium chlorite to the porous precursor of the composite stabilizer is 1:5-20.

[0022] In step (6), the mass ratio of the oxidized starch glue to the porous carrier of the composite sodium chlorite is 10:1-5.

[0023] A porous chlorine dioxide slow-release fresh-keeping paper prepared by the preparation method comprises a paper base, a porous carrier is fixed on the paper base by oxidized starch glue, the porous carrier is loaded with sodium chlorite, an activator, and a stabilizer, 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.

[0024] The oxidized starch glue adopts corn starch as raw material and is prepared by using an oxidant oxidation method: the oxidant is potassium permanganate or hydrogen peroxide; specifically, distilled water, corn starch, sodium hydroxide, and potassium permanganate are used at a mass ratio of 100:5-20:0.1-1:1-5, heated and stirred in a three-necked flask in a 80-100℃ water bath for 30 minutes to obtain the oxidized starch glue.

[0025] Another technical problem to be solved by the present application is to maintain long-acting release of chlorine dioxide. It is found through experiments that the synthesis temperature of the porous carrier, the type and amount of the added surfactant, the calcination temperature, and the type and amount of the added solvent can control the pore size and specific surface area of the prepared carrier, and the pore size and specific surface area of the porous carrier have a direct impact on the loading amount of sodium chlorite. The amount of the added stabilizer and the type of the porous carrier are closely related to the slow-release speed of chlorine dioxide.

[0026] The specific surface area of the porous carrier is 10-1000 m 2 / g; The pore size of the porous carrier is 1-100 nm.

[0027] The present application has the following beneficial effects: 1. Single-piece paper-based structure, no need for AB paper-based lamination, sealed and stored before use. Open the sealing strip when in use, and use the moisture in the air and the moisture evaporated from the fruit to trigger the slow release of chlorine dioxide. The reagents used in the preparation process are conveniently recycled and will not cause environmental pollution.

[0028] 2. The porous carrier structure increases the specific surface area and improves the loading amount of sodium chlorite, and the maximum loading amount of sodium chlorite can exceed 20%.

[0029] 3. The porous structure is beneficial to the single dispersion of the activator heteroacid, stabilizes the release speed of chlorine dioxide, and effectively prevents the phenomenon of explosive release. The effective slow-release time of chlorine dioxide exceeds 6 months.

[0030] 4. Fruit preservation test: blueberries can be preserved at room temperature for more than 30 days. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is a SEM image of the activator-embedded porous honeycomb-like cobalt tetraoxide material prepared in Example 1; Figure 2 is a graph of the relationship between the release amount of chlorine dioxide and time; Figure 3 is a blueberry preservation experiment graph. DETAILED DESCRIPTION

[0032] The technical solutions of the present application are further described below with specific examples.

[0033] In the present application, the raw materials and equipment used, unless specified, can be purchased from the market or commonly used in the art. The methods in the following examples, unless specified, are conventional methods in the art.

[0034] Oxidized starch glue preparation example 1: Distilled water, corn starch, sodium hydroxide, and potassium permanganate were used in a mass ratio of 100:10:0.5:2 in a three-necked flask, heated and stirred in a 90°C water bath for 30 minutes to obtain the oxidized starch glue.

[0035] Oxidized starch glue preparation example 2: Distilled water, corn starch, sodium hydroxide, and potassium permanganate were used in a mass ratio of 100:5:0.1:1 in a three-necked flask, heated and stirred in an 80°C water bath for 30 minutes to obtain the oxidized starch glue.

[0036] Oxidized starch glue preparation example 3: Distilled water, corn starch, sodium hydroxide, and potassium permanganate were used in a mass ratio of 100:20:1:5 in a three-necked flask, heated and stirred in a 100°C water bath for 30 minutes to obtain the oxidized starch glue.

[0037] Example 1: 3g of surfactant PEI was dissolved in 30 mL of n-butanol and stirred uniformly, then 0.4g of citric acid (CA) was added and stirred uniformly, followed by the addition of 2g of cobalt nitrate tetrahydrate, which was stirred until dispersed uniformly, and finally 0.3g of ammonium molybdate was added and stirred until mixed uniformly. The above solution was transferred to a watch glass and reacted for 10h at a reaction temperature of 120°C. The reaction product was transferred to a muffle furnace and calcined at 350°C for 4h. An activated agent inlaid porous honeycomb-like tricobalt tetraoxide material was prepared.

[0038] 1g of gelatin was dispersed in 50 mL of deionized water to obtain a dispersion liquid. The above 3g of activated agent inlaid multi-level porous honeycomb-like tricobalt tetraoxide material was added to the dispersion liquid, stirred and soaked for 4h, and then the mixture was baked in a 100°C oven for 10h. Finally, the mixture was calcined in a muffle furnace at 350°C for 2h to obtain a porous precursor of a composite stabilizer.

[0039] 4g of the above porous precursor of a composite stabilizer was dispersed in 50 mL of deionized water to obtain a dispersion liquid. 0.8g of sodium chlorite was mixed with 10 mL of deionized water to obtain an oxidizing agent impregnation liquid. The dispersion liquid and the oxidizing agent impregnation liquid were mixed uniformly, stirred and soaked for 8h, and then baked at 100°C for 10h to obtain a porous carrier of a composite sodium chlorite.

[0040] Take 0.1 g of the porous carrier of the composite sodium chlorite, add 1 g of the oxidized starch glue (prepared in Preparation Example 1), and mix and stir in a water bath at 45°C for 30 min to obtain a coating liquid. Uniformly apply 50 mg of the coating liquid to a 10*10 cm paper base. Obtain a chlorine dioxide slow-release fresh-keeping paper.

[0041] Select blueberries that are uniform in size, similar in color, consistent in maturity, free of mechanical damage, and free of disease and pest rot: After picking, place the blueberries at 20°C for 4 h to dissipate the field heat, and evenly divide them into three groups, with 15 blueberries in each group. Group A: control group (without paper base); Group B: place into a 10*10 cm blank paper base; Group C: place into a 10*10 cm chlorine dioxide slow-release fresh-keeping paper base (prepared in Example 1); Group D (conventional A+B composite paper base group): take 0.1 g of the porous carrier of the composite sodium chlorite (without the activator ammonium molybdate), add 1 g of the oxidized starch glue (prepared in Preparation Example 1), and mix and stir in a water bath at 45°C for 30 min to obtain a coating liquid. Uniformly apply 50 mg of the coating liquid to a 10*10 cm A paper base (10 g in weight); take 0.3 g of ammonium molybdate, add 1 g of the oxidized starch glue (prepared in Preparation Example 1), and mix and stir in a water bath at 45°C for 30 min to obtain a coating liquid. Uniformly apply 50 mg of the coating liquid to a 10*10 cm B paper base, and separate during storage and adhere during use. Place in a closed room at room temperature.

[0042] Figure 1 The SEM image of the activator-inlaid porous honeycomb cobaltosic oxide material prepared in Example 1 was observed, and it was found that the material had a porous honeycomb structure.

[0043] Figure 2 It is a chlorine dioxide release amount-time relationship diagram. As can be seen from the diagram, the release speed of chlorine dioxide is very stable, and there is no burst release phenomenon.

[0044] Figure 3 It is a blueberry fresh-keeping experiment diagram. In the diagram, from top to bottom, the first row is the experimental results on the 0th day, the second row is the experimental results on the 3rd day, the third row is the experimental results on the 7th day, and the fourth row is the experimental results on the 27th day. The blueberry rot rate of groups A-D on the 0th day (the same day) was 0; on the 3rd day, the blueberry rot rate of groups A, C, and D was 0, and the blueberry rot rate of group B was about 7%; on the 7th day, the blueberry rot rate of group A was about 7%, the blueberry rot rate of group B was about 15%, and the blueberry rot rate of groups C and D was 0; on the 27th day, the blueberry rot rate of groups A and B was 100%, and the blueberry rot rate of groups C and D was still 0. As can be clearly seen from the diagram, the chlorine dioxide fresh-keeping paper can effectively maintain the freshness of the blueberries, significantly reduce the blueberry rot rate, and prolong the storage period.

[0045] Example 2: 2.5 g of surfactant P123 was dissolved in 30 mL of methanol and stirred until uniform, then 0.37 g of CA was added and stirred until uniform, then 2.1 g of cobalt nitrate tetrahydrate was added and stirred until uniform, then 0.3 g of ammonium molybdate was added and stirred until uniform, the above solution was transferred to a watch glass and reacted for 10 h at a reaction temperature of 120°C, and the reaction product was transferred to a muffle furnace and calcined at 350°C for 4 h. An activated agent-inlaid mesoporous honeycomb cobaltosic oxide material was prepared.

[0046] 1 g of gelatin was dispersed in 50 mL of deionized water to obtain a dispersion liquid, 3 g of the activated agent-inlaid hierarchical porous honeycomb cobaltosic oxide material was added to the dispersion liquid, and stirring impregnation was performed for 4 h, then the mixture was baked in an oven at 100°C for 10 h, and finally calcined at 350°C in a muffle furnace for 2 h to obtain a porous precursor of a composite stabilizer.

[0047] 4 g of the porous precursor of the composite stabilizer was dispersed in 50 mL of deionized water to obtain a dispersion liquid, 0.8 g of sodium chlorite was mixed with 10 mL of deionized water to obtain an oxidizing agent impregnation liquid, the dispersion liquid and the oxidizing agent impregnation liquid were mixed until uniform, stirring impregnation was performed for 8 h, and then the mixture was baked at 100°C for 10 h to obtain a porous carrier of a composite sodium chlorite.

[0048] 0.2 g of the porous carrier of the composite sodium chlorite was added to 0.5 g of oxidized starch glue (prepared according to Preparation Example 1 of the oxidized starch glue), and mixed and stirred in a 45°C water bath for 30 min to obtain a coating liquid. 50 mg of the coating liquid was evenly applied to a 10*10 cm paper base to obtain a chlorine dioxide slow-release fresh-keeping paper.

[0049] Example 3: 3 g of surfactant PEI was dissolved in 30 mL of n-butanol and stirred until uniform, then 0.4 g of CA was added and stirred until uniform, then 3 g of aluminum nitrate hexahydrate was added and stirred until uniform, then 0.3 g of phosphotungstic acid was added and stirred until uniform, the above solution was transferred to a watch glass and reacted for 10 h at a reaction temperature of 120°C, and the reaction product was transferred to a muffle furnace and calcined at 350°C for 4 h. An activated agent-inlaid porous alumina material was prepared.

[0050] 1 g of nanosilica was dispersed in 50 mL of deionized water to obtain a dispersion liquid, 3 g of the activated agent-inlaid porous alumina material was added to the dispersion liquid, and stirring impregnation was performed for 4 h, then the mixture was baked in an oven at 100°C for 10 h, and finally calcined at 350°C in a muffle furnace for 2 h to obtain a porous precursor of a composite stabilizer.

[0051] Take 4 g of the above composite stabilizer porous precursor dispersion in 50 mL of deionized water to obtain a dispersion; take 0.8 g of sodium chlorite and mix with 10 mL of deionized water to obtain an oxidizing agent impregnation solution; mix the dispersion and the oxidizing agent impregnation solution uniformly, stir and impregnate for 8 h, and bake at 100 ℃ for 10 h to obtain a composite precursor.

[0052] Take 0.2 g of the composite sodium chlorite porous carrier, add 0.5 g of oxidized starch glue (prepared in Preparation Example 1), and mix and stir in a 45 ℃ water bath for 30 min to obtain a coating liquid. Uniformly apply 50 mg of the coating liquid to a 10*10 cm paper base to obtain a chlorine dioxide slow-release fresh-keeping paper.

[0053] Example 4 Dissolve 3 g of surfactant F127 in 15 mL of acetonitrile and stir uniformly, then add 0.3 g of ascorbic acid and stir uniformly, then add 1.5 g of lanthanum nitrate and stir until dispersed uniformly, and finally add 0.03 g of tartaric acid and stir to mix uniformly. Transfer the above solution to a watch glass and react for 24 h at a reaction temperature of 110 ℃. Transfer the reaction product to a muffle furnace and calcine at 300 ℃ for 6 h. An activated agent-inlaid porous honeycomb lanthanum oxide material is prepared.

[0054] Take 1 g of gelatin and disperse it in 50 mL of deionized water to obtain a dispersion. Add the above 1 g of activated agent-inlaid multi-level porous honeycomb lanthanum oxide material to the dispersion, stir and impregnate for 1 h, then bake the mixture in a 60 ℃ oven for 15 h, and finally calcine in a muffle furnace at 300 ℃ for 6 h to obtain a composite stabilizer porous precursor.

[0055] Take 5 g of the above composite stabilizer porous precursor and disperse it in 50 mL of deionized water to obtain a dispersion; take 0.5 g of sodium chlorite and mix with 10 mL of deionized water to obtain an oxidizing agent impregnation solution; mix the dispersion and the oxidizing agent impregnation solution uniformly, stir and impregnate for 1 h, and bake at 60 ℃ for 15 h to obtain a composite sodium chlorite porous carrier.

[0056] Take 0.2 g of the composite sodium chlorite porous carrier, add 1 g of oxidized starch glue (prepared in Preparation Example 1), and mix and stir in a 40 ℃ water bath for 30 min to obtain a coating liquid. Uniformly apply 500 mg of the coating liquid to a 10*10 cm paper base to obtain a chlorine dioxide slow-release fresh-keeping paper.

[0057] Example 5 Take 3g surfactant P123 dissolved in 60 mL of ethanol, stir evenly, then add 3g of CA, stir evenly, then add 15g praseodymium acetate, stir until evenly dispersed, finally add 1.5g silicotungstic acid, stir and mix evenly, transfer the above solution to a watch glass and react for 10h at a reaction temperature of 130℃, transfer the reaction product to a muffle furnace and calcine at 500℃ for 2h. The activated agent inlaid porous honeycomb praseodymium oxide material is prepared.

[0058] Take 1g of gelatin and disperse it in 100 mL of deionized water to obtain a dispersion liquid, add the above 20g activated agent inlaid hierarchical porous honeycomb praseodymium oxide material to the dispersion liquid, stir and soak for 24h, then bake the mixture in an oven at 80℃ for 12h; finally, calcine in a muffle furnace at 500℃ for 2h to obtain a composite stabilizer porous precursor.

[0059] Take 100g of the above composite stabilizer porous precursor and disperse it in 300 mL of deionized water to obtain a dispersion liquid; take 5g of sodium chlorite and mix it with 10 mL of deionized water to obtain an oxidizing agent impregnation liquid; mix the dispersion liquid and the oxidizing agent impregnation liquid evenly, stir and soak for 24h, and bake at 80℃ for 12h to obtain a composite sodium chlorite porous carrier.

[0060] Take 0.5g of the composite sodium chlorite porous carrier, add 2.5g of oxidized starch glue (prepared according to the preparation example 1 of oxidized starch glue), and mix and stir in a 50℃ water bath for 30 min to obtain a coating liquid. Uniformly apply 100mg of the coating liquid to a 10*10cm paper base to obtain a chlorine dioxide slow-release fresh-keeping paper.

[0061] Example 6 Take 5g of the composite stabilizer porous precursor prepared in example 1 and disperse it in 50mL of deionized water to obtain a dispersion liquid; take 1g of sodium chlorite and mix it with 10 mL of deionized water to obtain an oxidizing agent impregnation liquid; mix the dispersion liquid and the oxidizing agent impregnation liquid evenly, stir and soak for 8h, and bake at 100℃ for 12h to obtain a composite sodium chlorite porous carrier.

[0062] Comparative example 1 Take 1g of sodium chlorite and add it to 20mL of water, stir until completely dissolved, and configure it as solution A; take 5g of activated carbon and disperse it in 20mL of water, configure it as solution B; quickly pour solution A into solution B, stir for 8h, and dry at 100℃ for 12h to obtain activated carbon loaded sodium chlorite.

[0063] Comparative example 2 Use the same method as comparative example 1, and replace the carrier with 4A molecular sieve.

[0064] Comparative example 3 Use the same method as comparative example 1, and replace the carrier with a mixture of activated carbon and 4A molecular sieve in a mass ratio of 1:1.

[0065] The slow-release effect of Example 6 and Comparative Examples 1-3 was determined in an open environment at room temperature, and the sodium chlorite loading rate refers to the percentage of sodium chlorite weight to carrier weight, and the specific results are as follows: .

[0066] As can be seen, compared with conventional porous carriers, the carrier of the present application has the highest loading amount of sodium chlorite and the best slow-release effect.

[0067] The above-described examples are only a preferred scheme of the present application, and do not limit the present application in any form, and other variants and modifications are possible without exceeding the technical scheme recorded in the claims.

Claims

1. A method for preparing a porous chlorine dioxide slow-release fresh-keeping paper, characterized in that: The steps include:

1. Preparation of Activator-Inlaid Porous Precursors (1) The surfactant and the organic solvent are mixed uniformly in a ratio of 1 g: 5-20 mL to obtain solution A; (2) Mixing the organic acid and solution A uniformly to obtain solution B; (3) Adding the metal salt and the activator to solution B, mixing them evenly, and then reacting at high temperature and calcining to obtain a porous precursor embedded with the activator; 2. Preparation of porous carrier of composite sodium chlorite: (4) The stabilizer and deionized water are stirred and mixed, and uniformly dispersed to obtain an impregnation solution; the porous precursor embedded with the activator is added to the impregnation solution, stirred and impregnated for 1-24 hours, and dried and calcined to obtain the porous precursor of the composite stabilizer; (5) Adding the porous precursor of the composite stabilizer to a sodium chlorite solution with a concentration of 0.05-0.5 g / mL, stirring and immersing for 1-24 hours, and then drying to obtain a porous carrier of composite sodium chlorite; 3. Preparation of sustained-release fresh-keeping paper: (6) Mix the porous carrier of composite sodium chlorite and oxidized starch glue, stir and mix in a 40-50°C water bath to form a coating solution; (7) Cut the paper base and place it in a dryer to remove moisture. Then evenly apply the coating liquid to the paper base with a coating amount of 0.5~5 mg / cm 2 , and obtain porous chlorine dioxide slow-release fresh-keeping paper.

2. The preparation method according to claim 1, characterized in that 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, ammonium molybdate and tartaric acid.

3. The preparation method according to claim 1, characterized in that The metal salt is a salt formed by one of aluminum, titanium, cobalt, zinc, copper, iron, cerium, zirconium, nickel, manganese, praseodymium and lanthanum, and the salt is nitrate, acetate and chlorate.

4. The preparation method according to claim 1, wherein The mass ratio of the surfactant, activator, metal salt and organic acid is 1:0.01~0.5:0.5~5:0.1~1.

5. The preparation method according to claim 1, wherein In step (3), the reaction temperature of the high temperature reaction is 100-150°C and the time is 1-72 h; in step (3) and step (4), the calcination temperature is 300-700°C and the time is 1-20 h.

6. The preparation method according to claim 1, wherein In step (4) and step (5), the drying parameters are: drying temperature 60-100°C, and time 1-20 h.

7. The preparation method according to claim 1, wherein In step (4), the stabilizer is one or a combination of two of silicon dioxide, gelatin, and starch, and the mass ratio of the porous precursor embedded with the stabilizer to the activator is 1: 1-20.

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

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

10. A porous chlorine dioxide sustained-release fresh-keeping paper prepared by the preparation method according to claim 1, comprising a paper base, characterized in that: A porous carrier is fixed on a paper base by oxidized starch glue, and sodium chlorite, an activator and a stabilizer are loaded on the porous carrier. The porous carrier is one of the 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.

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