Tannin-based foaming deoxidizer and preparation method thereof

Abstract

The invention discloses a tannin-based foaming deoxidizer and a preparation method thereof, and belongs to the technical field of food deoxidizers. The porous tannin-based foaming deoxidizer is developed by taking tannin as a main component and combining a foaming technology for the first time. The prepared tannin-based foaming deoxidizer is loose and porous, the structure is easier to adsorb gas, deoxidation reaction is facilitated, and then the deoxidation amount is increased. The tannin-based foaming deoxidizer prepared by the method is high in deoxidization amount (obviously higher than reduced iron powder), the deoxidization amount is slightly influenced by humidity, and the tannin-based foaming deoxidizer can be applied to wider scenes.

Description

Technical Field

[0001] The invention belongs to the technical field of food deoxidizers, and particularly relates to a tannin-based foaming deoxidizer and a preparation method thereof. Background Art

[0002] Deoxidizers, also known as deoxidizers or oxygen absorbers, are a type of additive that can absorb oxygen and slow down the oxidation of food. The importance of deoxidizers lies in their ability to provide an oxygen-free or low-oxygen environment, thereby maintaining product quality and extending its shelf life. Deoxidizers can be roughly divided into two categories: inorganic deoxidizers and organic deoxidizers according to their chemical composition. Inorganic deoxidizers can be roughly divided into two categories: one is a metal deoxidizer composed of iron, palladium, etc. The characteristics of iron-based deoxidizers are wide sources and low costs, but the deoxidation amount and deoxidation rate of iron-based deoxidizers are positively correlated with ambient humidity. The deoxidation effect of iron-based deoxidizers is minimal at low humidity, and high humidity will have an adverse effect on food storage. If leakage occurs during food storage, it will have a certain impact on human health and cannot pass the detection of food metal detectors. However, palladium-based deoxidizers are expensive, which limits their application scenarios. The other type is non-metallic deoxidizers represented by inorganic salts such as sodium bisulfite. The advantage of this type of non-metallic deoxidizer is that it can pass the detection of food metal detectors, but it will produce SO during the deoxidation process. 2 、SO 3 Gases such as these will affect the flavor of food.

[0003] At present, common organic deoxidizers are mainly divided into three categories. The first category is ascorbic acid deoxidizer, which has a fast deoxidation speed, but also has disadvantages such as high cost and the need for metal catalysts; the second category is α-tocopherol deoxidizer, which usually needs to be combined with transition metal catalysts such as iron, copper, manganese and cobalt for deoxidation; the third category is biological enzyme deoxidizer, such as glucose enzyme for deoxidation, but this deoxidizer wants to deoxidize, the food must contain glucose, because glucose is converted into gluconic acid during the reaction, which will cause the pH of the package to decrease. The biological enzyme deoxidizer requires a mild deoxidation condition. The temperature and pH value will affect the deoxidation efficiency of the enzyme, and the deoxidation conditions are relatively harsh.

[0004] Tannin is a natural plant polyphenol with a wide variety of species, widely distributed in the fruits, berries, leaves and flowers of woody and non-woody plants. Tannin can be divided into two categories according to its chemical structure: hydrolyzed tannin and condensed tannin. Hydrolyzed tannin is also called gallate tannin, such as gallnut tannin (see Figure 1 ), Tara tannin, oak tannin, etc.; condensed tannin is also called polyflavanol tannin (see Figure 1 ), such as bayberry tannin (see Figure 1 ), larch tannin, quebracho tannin, black wattle tannin, etc., with structural formulas such as Figure 1At present, the research on tannin mainly focuses on the antibacterial property, astringency, and complexing property of tannin, and there are no reports on the deoxidation of tannin and tannin deoxidizer. Summary of the invention

[0005] The purpose of the present invention is to provide a tannin-based foaming deoxidizer and a preparation method thereof. By taking tannin as the main component and combining the foaming technology, a porous tannin-based foaming deoxidizer is developed, and the deoxidation capacity is greatly improved.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] One of the technical solutions of the present invention is to provide a method for preparing a tannin-based foaming deoxidizer, comprising the steps of preparing a urea-formaldehyde foaming material using oxidized starch and urea as raw materials and adding tannin; the tannin is added into or directly loaded on the urea-formaldehyde foaming material before foaming.

[0008] Preferably, the tannin comprises one or more of gallnut tannin, bayberry tannin, larch tannin, black wattle tannin and quebracho tannin.

[0009] The tannins of the present invention are preferably from a wide range of sources, are easy to obtain, and are low in cost. Other tannins besides the above tannins can also achieve the technical purpose of the present invention.

[0010] Preferably, the mass ratio of the tannin to the oxidized starch is 3:1 to 10:1.

[0011] Preferably, the preparation method specifically includes method A, method B or method C;

[0012] The method A comprises the following steps: mixing oxidized starch, urea and water, adjusting the pH to be alkaline, adding tannin after reaction, adjusting the pH to neutral after further reaction, concentrating, adding an emulsifier and a foaming agent, adding a curing agent after stirring, continuing stirring, and finally curing to obtain a tannin-based foaming deoxidizer;

[0013] The method B comprises the following steps: mixing oxidized starch, urea and water, adjusting the pH to be alkaline, adding urea after the reaction, adjusting the pH to be acidic, adding tannin after the reaction, adjusting the pH to be neutral after the reaction, concentrating, adding an emulsifier and a foaming agent, adding a curing agent after stirring, continuing stirring, and finally curing to obtain a tannin-based foaming deoxidizer;

[0014] The method C comprises the following steps: mixing oxidized starch, urea and water, adjusting the pH to be alkaline, adding urea after the reaction, adjusting the pH to be acidic, adjusting the pH to be neutral after the reaction, concentrating, adding an emulsifier and a foaming agent, adding a curing agent after stirring, continuing stirring, and finally curing to obtain a urea-formaldehyde foaming material; and then immersing the urea-formaldehyde foaming material in a tannin solution to load the tannin on the urea-formaldehyde foaming material, and obtaining a tannin-based foaming deoxidizer after drying.

[0015] Optionally, in method A, method B and method C, the emulsifier includes but is not limited to Tween-80; the foaming agent includes but is not limited to petroleum ether, acetone or n-pentane; the curing agent includes but is not limited to citric acid, phosphoric acid, formic acid, acetic acid, dilute sulfuric acid or benzenesulfonic acid.

[0016] Preferably, in method A, method B and method C, the amount of the emulsifier added is 1 to 2% of the mass of the concentrated system; and / or the amount of the foaming agent added is 0.5 to 10% of the mass of the concentrated system; and / or the amount of the curing agent added is 2 to 15% of the mass of the concentrated system.

[0017] Preferably, in method A, method B and method C, adjusting the pH to be alkaline means adjusting the pH to 8-10; and / or, adjusting the pH to be acidic means adjusting the pH to 3-5.

[0018] Preferably, in method A, after adjusting the pH value to alkaline, the reaction temperature is 60-90° C. and the reaction time is 20-50 min, and after adding tannin, the reaction temperature is 60-90° C. and the reaction time is 0.5-3 h.

[0019] Preferably, in method B, after adjusting the pH value to alkaline, the reaction temperature is 70-120°C and the time is 20-50 min, and after adjusting the pH value to acidic, the reaction temperature is 100-130°C and the time is 12-18 h. Before adding tannin, the temperature is cooled to 60-90°C, and the reaction is continued for 0.5-3 h after adding tannin.

[0020] Preferably, in method C, after adjusting the pH value to alkaline, the reaction temperature is 70-120° C. and the reaction time is 20-50 min; after adjusting the pH value to acidic, the reaction temperature is 100-130° C. and the reaction time is 12-18 h.

[0021] Preferably, in method A, method B and method C, the curing temperature is 50 to 90° C. and the curing time is 2 to 9 hours.

[0022] The second technical solution of the present invention is to provide a tannin-based foaming deoxidizer prepared according to the preparation method of the above-mentioned tannin-based foaming deoxidizer.

[0023] The application conditions of the tannin-based foaming deoxidizer are: temperature 4-40° C. and relative humidity 40-100% RH.

[0024] The third technical solution of the present invention is to provide a deoxidizer, the components of which include the above-mentioned tannin-based foaming deoxidizer.

[0025] Preferably, the deoxidizer component further comprises sodium carbonate.

[0026] The sodium carbonate added in the present invention can provide an alkaline environment for the deoxygenation reaction of tannin, which is helpful for the ionization of protons in the tannin molecules, further improving the oxygen absorption characteristics of tannin and enhancing the deoxygenation effect.

[0027] More preferably, the deoxidizer component further comprises a water-absorbing and hygroscopic substance.

[0028] Wherein, sodium carbonate is sodium carbonate decahydrate or anhydrous sodium carbonate, and the amount of sodium carbonate added does not exceed 3 times the mass of tannin. Sodium carbonate can be directly blended with the tannin-based foaming deoxidizer to obtain the deoxidizer, or can be added when the tannin-based foaming deoxidizer is solidified to obtain the deoxidizer; the water-absorbing and hygroscopic substances include vermiculite and the like.

[0029] The deoxidizer is applied under the following conditions: temperature 4-40° C., relative humidity 40-100% RH.

[0030] The beneficial technical effects of the present invention are as follows:

[0031] The present invention uses tannin as the main raw material to prepare a tannin-based foaming deoxidizer for the first time. The prepared tannin-based foaming deoxidizer is loose and porous, and the structure is more likely to adsorb gas, which is beneficial to the deoxidation reaction and further increases the deoxidation amount.

[0032] The tannin-based foaming deoxidizer prepared by the present invention has a high deoxidation capacity (significantly higher than reduced iron powder), and the deoxidation capacity is less affected by humidity, and can be applied to a wider range of scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is the structural formula of part of tannin.

[0034] Figure 2 This is a comparison chart of the deoxidation performance of the tannin-based foaming deoxidizer prepared in Example 4 and the reduced iron powder.

[0035] Figure 3 This is the SEM image of the tannin-based foaming deoxidizer prepared in Example 16. DETAILED DESCRIPTION

[0036] Now, various exemplary embodiments of the present invention are described in detail, and this detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present invention. It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention.

[0037] In addition, for the numerical range in the present invention, it is understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0038] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the invention pertains. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention.

[0039] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0040] The steps for preparing the iron oxide powder used in the embodiment of the present invention are as follows:

[0041] 50 g of starch was reacted with 125 mL of sodium periodate solution (0.5 mol / L) at pH = 2.5 in the dark for 2.5 h, ethylene glycol was added to terminate the reaction, and the solid product was filtered and washed with deionized water until the filtrate was neutral, and then dried to obtain oxidized starch.

[0042] The mass percentages of the emulsifier, foaming agent and curing agent in the embodiment of the present invention are all mass percentages of the viscous liquid.

[0043] Example 1

[0044] After dissolving 4g of oxidized starch in 60mL of deionized water, 0.6g of urea was added, the pH was adjusted to 8.5, and the mixture was reacted at 90°C for 30min. Then, 16g of bayberry tannin was added, and the mass ratio of tannin to oxidized starch was 4:1. The mixture was reacted for 1.5h, cooled to room temperature, and the pH was adjusted to be neutral. The solution was concentrated by rotary evaporation to a viscous liquid. 1.5wt% of Tween-80 and 5wt% of petroleum ether foaming agent were added to the viscous liquid, and the mixture was mechanically stirred at 600rpm for 10min. Then, 10wt% of citric acid as a curing agent was added, and the mixture was mechanically stirred at 600rpm for 5min. The mixture was placed in an oven at 70°C for curing for 5h. The mixture was crushed and passed through a 120-mesh sieve to obtain a tannin-based foaming deoxidizer.

[0045] Example 2

[0046] Compared with Example 1, the only difference is that the bayberry tannin is replaced by the gallnut tannin of the same mass.

[0047] The deoxidation amount of the tannin-based foaming deoxidizer prepared in Examples 1 and 2 was measured at 35° C. and 100% RH. The results are shown in Table 1.

[0048] Table 1 Different types of tannin (deoxygenation amount is based on tannin mass)

[0049] Example 1 Example 2 Deoxygenation amount (mL / g) 31.30 41.34

[0050] Example 3

[0051] After dissolving 10g of oxidized starch in 150mL of deionized water, 1.05g of urea was added, the pH was adjusted to 8.5, and the reaction was carried out at 90°C for 50min. Then, 0.45g of urea was added, the pH was adjusted to 2.5, and the reaction was carried out at 120°C for 6h. The flask was then transferred to a 70°C water bath. After the temperature stabilized, 35g of bayberry tannin was added to the flask, and the mass ratio of tannin to oxidized starch was 3.5:1. The reaction was continued for 0.5h. The solution was cooled to room temperature, the pH was adjusted to neutral, and the solution was concentrated by rotary evaporation to a viscous liquid. 1.5wt% of Tween-80 and 5wt% of petroleum ether foaming agent were added to the viscous liquid, and mechanical stirring was carried out at 600rpm for 10min. Then, 10wt% of citric acid as a curing agent was added, and mechanical stirring was carried out at 600rpm for 5min. The solution was placed in an oven at 70°C for curing for 5h, and the tannin-based foaming deoxidizer was obtained after crushing and passing through a 120-mesh sieve.

[0052] Example 4

[0053] After dissolving 10g of oxidized starch in 150mL of deionized water, 1.05g of urea was added, the pH was adjusted to 8.5, and the reaction was carried out at 90°C for 50min. Then, 0.45g of urea was added, the pH was adjusted to 2.5, and the reaction was carried out at 120°C for 6h. The flask was then transferred to a 70°C water bath, and 45g of bayberry tannin was added to the flask after the temperature stabilized. The mass ratio of tannin to oxidized starch was 4.5:1. The reaction was continued for 0.5h, cooled to room temperature, and the pH was adjusted to neutral. The solution was concentrated by rotary evaporation to a viscous liquid. 1.5wt% of Tween-80 and 2.5wt% of petroleum ether foaming agent were added to the viscous liquid, and mechanical stirring was carried out at 600rpm for 10min. Then, 6wt% of citric acid as a curing agent was added, and mechanical stirring was carried out at 600rpm for 5min. The mixture was placed in an oven at 70°C for curing for 5h, and the tannin-based foaming deoxidizer was obtained after crushing and passing through a 120-mesh sieve.

[0054] The deoxidation performance of the tannin-based foaming deoxidizer prepared in Example 4 was compared with that of the reduced iron powder. The deoxidation amounts of the two under different conditions were shown in Table 1. Figure 2 .

[0055] from Figure 2 It can be seen that under the conditions of 35°C and 100% RH, the deoxygenation amount of the tannin-based foaming deoxidizer of the present invention is as high as 61.32 mL / g (based on the weight of tannin), and the deoxygenation amount of the reduced iron powder is 53.53 mL / g. Under the conditions of 35°C and 83% RH, the deoxygenation amount of the tannin-based foaming deoxidizer of the present invention is as high as 48.72 mL / g (based on the weight of tannin), and the deoxygenation amount of the reduced iron powder is 8.87 mL / g. Under the conditions of 35°C and 75% RH, the deoxygenation amount of the tannin-based foaming deoxidizer of the present invention is as high as 34.21 mL / g (based on the weight of tannin), and the deoxygenation amount of the reduced iron powder is 6.81 mL / g; under the conditions of 35°C and 55% RH, the deoxygenation amount of the tannin-based foaming deoxidizer of the present invention is as high as 22.14 mL / g (based on the weight of tannin), and the deoxygenation amount of the reduced iron powder is 3.76 mL / g. The deoxygenation amount of the tannin-based foaming deoxidizer prepared by the invention is less affected by environmental humidity and can be used normally even under low humidity.

[0056] Example 5

[0057] Compared with Example 3, the only difference is that the mass ratio of tannin to oxidized starch is adjusted to 5.5:1.

[0058] The deoxidation amount of the tannin-based foaming deoxidizer prepared in Examples 3 to 5 was measured at 35° C. and 100% RH. The results are shown in Table 2.

[0059] Table 2 Different mass ratios of tannin and oxidized starch (deoxygenation amount is based on tannin mass)

[0060] Example 3 Example 4 Example 5 Deoxygenation amount (mL / g) 8.18 61.32 15.18

[0061] Example 6

[0062] After dissolving 10g of oxidized starch in 150mL of deionized water, 1.05g of urea was added, the pH was adjusted to 8.5, and the reaction was carried out at 90°C for 50min. Then, 0.45g of urea was added, the pH was adjusted to 2.5, and the reaction was carried out at 120°C for 6h. The flask was then transferred to a 70°C water bath. After the temperature stabilized, 45g of bayberry tannin was added to the flask, and the mass ratio of tannin to oxidized starch was 4.5:1. The reaction was continued for 0.5h. The flask was cooled to room temperature, the pH was adjusted to neutral, and the solution was concentrated by rotary evaporation to a viscous liquid. 1.5wt% of Tween-80 and 0.75wt% of petroleum ether foaming agent were added to the viscous liquid, and mechanical stirring was carried out at 600rpm for 10min. Then, 10wt% of citric acid as a curing agent was added, and mechanical stirring was carried out at 600rpm for 5min. The tannin-based foaming deoxidizer was obtained by curing in an oven at 70°C for 5h. The tannin-based foaming deoxidizer was obtained by pulverizing and passing through a 120-mesh sieve.

[0063] Example 7

[0064] Compared with Example 6, the only difference is that the addition amount of petroleum ether foaming agent is adjusted to 2.5wt%.

[0065] Example 8

[0066] Compared with Example 6, the only difference is that the addition amount of petroleum ether foaming agent is adjusted to 5wt%.

[0067] The deoxygenation amount of the tannin-based foaming deoxidizer prepared in Examples 6 to 8 mixed with anhydrous sodium carbonate in a mass ratio of 1:1 at 35° C. and 100% RH was measured. The results are shown in Table 3.

[0068] Table 3 Different foaming agent dosage (deoxygenation amount is based on tannin mass)

[0069] Example 6 Example 7 Example 8 Deoxygenation amount (mL / g) 103.86 123.66 48.31

[0070] Example 9

[0071] After dissolving 10g of oxidized starch in 150mL of deionized water, 1.05g of urea was added, the pH was adjusted to 8.5, and the reaction was carried out at 90°C for 50min. Then, 0.45g of urea was added, the pH was adjusted to 2.5, and the reaction was carried out at 120°C for 6h. The flask was then transferred to a 70°C water bath. After the temperature stabilized, 45g of bayberry tannin was added to the flask, and the mass ratio of tannin to oxidized starch was 4.5:1. The reaction was continued for 0.5h. The flask was cooled to room temperature, the pH was adjusted to neutral, and the solution was concentrated by rotary evaporation to a viscous liquid. 1.5wt% of Tween-80 and 2.5wt% of petroleum ether foaming agent were added to the viscous liquid, and mechanical stirring was carried out at 600rpm for 10min. Then, 4wt% of citric acid as a curing agent was added, and mechanical stirring was carried out at 600rpm for 5min. The tannin-based foaming deoxidizer was obtained by curing in an oven at 70°C for 5h. The tannin-based foaming deoxidizer was obtained by pulverizing and passing through a 120-mesh sieve.

[0072] Example 10

[0073] Compared with Example 9, the only difference is that the addition amount of the curing agent citric acid is adjusted to 6 wt %.

[0074] Embodiment 11

[0075] Compared with Example 9, the only difference is that the addition amount of the curing agent citric acid is adjusted to 8 wt %.

[0076] The deoxidation amount of the tannin-based foaming deoxidizer prepared in Examples 9 to 11 mixed with anhydrous sodium carbonate in a mass ratio of 1:1 at 35° C. and 100% RH was measured. The results are shown in Table 4.

[0077] Table 4 Different curing agent dosage (deoxidation amount is based on tannin mass)

[0078] Example 9 Example 10 Embodiment 11 Deoxygenation amount (mL / g) 98.08 140.62 123.66

[0079] Example 12

[0080] After dissolving 10g of oxidized starch in 150mL of deionized water, 1.05g of urea was added, the pH was adjusted to 8.5, and the reaction was carried out at 90°C for 50min. Then, 0.45g of urea was added, the pH was adjusted to 2.5, and the reaction was carried out at 120°C for 6h. The flask was then transferred to a 70°C water bath, and 45g of bayberry tannin was added to the flask after the temperature stabilized. The mass ratio of tannin to oxidized starch was 4.5:1. The reaction was continued for 0.5h, cooled to room temperature, and the pH was adjusted to neutral. The solution was concentrated by rotary evaporation to a viscous liquid. 1.5wt% of Tween-80 and 2.5wt% of petroleum ether foaming agent were added to the viscous liquid, and mechanical stirring was carried out at 600rpm for 10min. Then, 6wt% of citric acid as a curing agent was added, and mechanical stirring was carried out at 600rpm for 5min. The solution was placed in an oven at 70°C for curing for 3h, and the tannin-based foaming deoxidizer was obtained after crushing and passing through a 120-mesh sieve.

[0081] Embodiment 13

[0082] Compared with Example 12, the only difference is that the curing time is adjusted to 5 hours.

[0083] Embodiment 14

[0084] Compared with Example 12, the only difference is that the curing time is adjusted to 7 hours.

[0085] The deoxidation amount of the tannin-based foaming deoxidizer prepared in Examples 12 to 14 and sodium carbonate decahydrate mixed in a mass ratio of 1:1 at 35° C. and 100% RH was measured. The results are shown in Table 5.

[0086] Table 5 Different curing time (deoxidation amount is based on tannin mass)

[0087] Example 12 Embodiment 13 Embodiment 14 Deoxygenation amount (mL / g) 50.42 140.62 82.87

[0088] Embodiment 15

[0089] After dissolving 10g of oxidized starch in 150mL of deionized water, add 1.05g of urea, adjust the pH to 8.5, react at 90℃ for 50min, then add 0.45g of urea, adjust the pH to 2.5, react at 120℃ for 6h, transfer the flask to a 70℃ water bath, add bayberry tannin to the flask after the temperature stabilizes, the mass ratio of tannin to oxidized starch is 4.5:1, continue to react for 0.5h, cool to room temperature, adjust the pH to neutral, and rotary evaporate the solution. The mixture was concentrated into a viscous liquid, 1.5 wt% of Tween-80 and 2.5 wt% of petroleum ether foaming agent were added to the viscous liquid, and mechanically stirred at 600 rpm for 10 min. Then, 6 wt% of citric acid as a curing agent was added, and mechanically stirred at 600 rpm for 5 min. Finally, sodium carbonate decahydrate was added, and the mass ratio of sodium carbonate decahydrate to urea-formaldehyde resin was 1:2. The mixture was mechanically stirred at 600 rpm for 10 min. The mixture was placed in an oven at 70° C. for curing for 5 h. After being crushed, the mixture was sieved through a 120-mesh sieve to obtain a deoxidizer.

[0090] Example 16

[0091] Compared with Example 15, the only difference is that the amount of sodium carbonate decahydrate added is adjusted to a mass ratio of 1:1 with the urea-formaldehyde resin.

[0092] Embodiment 17

[0093] Compared with Example 15, the only difference is that the amount of sodium carbonate decahydrate added is adjusted to a mass ratio of 2:1 to the urea-formaldehyde resin.

[0094] The deoxygenation amount of the tannin-based foaming deoxidizer prepared in Examples 15 to 17 was tested at 35° C. and 100% RH. The results are shown in Table 6.

[0095] Table 6 Different ratios of tannin and sodium carbonate during curing (deoxidation amount is based on tannin mass)

[0096] Embodiment 15 Example 16 Embodiment 17 Deoxygenation amount (mL / g) 106.22 182.23 155.22

[0097] The SEM image of the tannin-based foaming deoxidizer prepared in Example 16 is shown in Figure 3 . Figure 3 It shows that the tannin-based foaming deoxidizer prepared by the present invention is loose and porous, and the structure is more likely to adsorb gas, which is beneficial to the deoxidation reaction and further increases the deoxidation amount.

[0098] Embodiment 18

[0099] (1) After 30 g of oxidized starch was dissolved in 450 mL of deionized water, 3.15 g of urea was added, the pH was adjusted to 8.5, and the mixture was reacted at 90° C. for 50 min. Then, 1.35 g of urea was added, the pH was adjusted to 2.5, and the mixture was reacted at 120° C. for 12 h. The mixture was cooled to room temperature, the pH was adjusted to neutral, and the solution was concentrated by rotary evaporation to a viscous liquid. 1.5 wt % of Tween-80 and 2.5 wt % of petroleum ether as a foaming agent were added to the viscous liquid, and the mixture was mechanically stirred at 600 rpm for 10 min. Then, 6 wt % of citric acid as a curing agent was added, and the mixture was mechanically stirred at 600 rpm for 5 min. The mixture was placed in an oven at 120° C. for curing for 12 h. After being crushed, the mixture was sieved with a 120-mesh sieve. The sieved powder was repeatedly washed with deionized water until the washed water was transparent and colorless. The urea-formaldehyde porous material was obtained after drying.

[0100] (2) Prepare 250 mL of 15 g / L gallnut tannin solution, add 1 g of urea-formaldehyde adsorbent material, adjust the pH to 2.5, put it in a shaker at 140 rpm, shake for 6 h, filter it, and vacuum dry it to obtain a tannin-based foaming deoxidizer.

[0101] The deoxygenation amount of the tannin-based foaming deoxidizer prepared in Example 18 was tested under different conditions. The results are shown in Table 7.

[0102] Table 7 Different deoxygenation conditions (deoxygenation amount is based on tannin mass)

[0103] Temperature(℃) Relative humidity (%RH) Deoxygenation amount (mL / g) 35 75 35.53 25 85 24.31 6 100 2.75

[0104] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing a tannin-based foaming deoxidizer, characterized in that: The method comprises the steps of preparing a urea-formaldehyde foaming material with oxidized starch and urea as raw materials and adding tannin; the tannin is added into or directly loaded on the urea-formaldehyde foaming material before foaming.

2. The preparation method of the tannin-based foaming deoxidizer according to claim 1, characterized in that: The tannins include one or more of gallnut tannins, bayberry tannins, larch tannins, black wattle tannins and quebracho tannins.

3. The preparation method of the tannin-based foaming deoxidizer according to claim 1, characterized in that: The mass ratio of the tannin to the oxidized starch is 3:1 to 10:

1.

4. The method for preparing the tannin-based foaming deoxidizer according to any one of claims 1 to 3, characterized in that: The preparation method specifically includes method A, method B or method C; The method A comprises the following steps: mixing oxidized starch, urea and water, adjusting the pH to be alkaline, adding tannin after reaction, adjusting the pH to neutral after further reaction, concentrating, adding an emulsifier and a foaming agent, adding a curing agent after stirring, continuing stirring, and finally curing to obtain a tannin-based foaming deoxidizer; The method B comprises the following steps: mixing oxidized starch, urea and water, adjusting the pH to be alkaline, adding urea after the reaction, adjusting the pH to be acidic, adding tannin after the reaction, adjusting the pH to be neutral after the reaction, concentrating, adding an emulsifier and a foaming agent, adding a curing agent after stirring, continuing stirring, and finally curing to obtain a tannin-based foaming deoxidizer; The method C comprises the following steps: mixing oxidized starch, urea and water, adjusting the pH to be alkaline, adding urea after the reaction, adjusting the pH to be acidic, adjusting the pH to be neutral after the reaction, concentrating, adding an emulsifier and a foaming agent, adding a curing agent after stirring, continuing stirring, and finally curing to obtain a urea-formaldehyde foaming material; and then immersing the urea-formaldehyde foaming material in a tannin solution to load the tannin on the urea-formaldehyde foaming material, and obtaining a tannin-based foaming deoxidizer after drying.

5. The preparation method of the tannin-based foaming deoxidizer according to claim 4, characterized in that: In method A, after adjusting the pH value to alkaline, the reaction temperature is 60-90°C and the time is 20-50 minutes. After adding tannin, the reaction temperature is 60-90°C and the time is 0.5-3 hours.

6. The method for preparing a tannin-based foaming deoxidizer according to claim 4, wherein: In method B, after adjusting the pH value to alkaline, the reaction temperature is 70-120°C and the time is 20-50 minutes. After adjusting the pH value to acidic, the reaction temperature is 100-130°C and the time is 12-18 hours. The temperature is cooled to 60-90°C before adding tannin, and the reaction is continued for 0.5-3 hours after adding tannin.

7. The preparation method of the tannin-based foaming deoxidizer according to claim 4, characterized in that: In method C, after adjusting the pH value to alkaline, the reaction temperature is 70-120° C. and the reaction time is 20-50 min. After adjusting the pH value to acidic, the reaction temperature is 100-130° C. and the reaction time is 12-18 h.

8. A tannin-based foaming deoxidizer prepared according to the method for preparing a tannin-based foaming deoxidizer according to any one of claims 1 to 7.

9. A deoxidizer, characterized in that The component comprises the tannin-based foaming deoxidizer as claimed in claim 8.

10. The deoxidizer according to claim 9, characterized in that The deoxidizer component further comprises sodium carbonate.

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