A cellulose coated slow-release oxidant and its preparation method

Abstract

The present invention relates to the field of environmental remediation technology, and specifically to a cellulose coated slow-release oxidant and a preparation method thereof. Among them, a preparation method of a cellulose coated slow-release oxidant comprises: obtaining a polymer gel: grinding a dispersant and an oxidant to obtain a dispersant / oxidant complex, mixing a natural polymer material with a solvent to prepare a natural polymer material solution, adding an activator, a cross-linking agent 1, and a dispersant / oxidant complex to the natural polymer material solution and allowing the solution to react to obtain a polymer gel; obtaining a coating liquid: mixing natural cellulose with a solvent to prepare a natural cellulose solution, adding a cross-linking agent 2, a pore-forming agent and a catalyst to the natural cellulose solution and stirring to obtain a coating liquid; covering the coating liquid on the surface of the polymer gel, and then subjecting the coating liquid to an acid soaking treatment to obtain the coating liquid. The cellulose coated slow-release oxidant prepared by the present invention has the advantages of high safety, low cost, good coating effect, and controllable release efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of environmental restoration, and in particular to a cellulose coated slow-release oxidant and a preparation method thereof. Background Art

[0002] Since organic matter is difficult to degrade under natural conditions, it is extremely necessary to repair it. Currently, the commonly used groundwater remediation technologies are in-situ remediation and ex-situ remediation. In-situ remediation technology mainly includes chemical remediation and biological remediation. Among them, in-situ chemical oxidation technology has received widespread attention due to its advantages such as good effect, low price and easy deployment. However, existing in-situ chemical oxidation remediation agents have defects such as fast dissipation, lack of sustainability, low electron transfer efficiency, instability, serious waste and easy to cause secondary pollution to the environment.

[0003] In recent years, slow-release technology has been used for in-situ groundwater remediation. Slow-release materials are groundwater remediation materials prepared based on in-situ chemical remediation technology and controlled release technology. With the help of controlled slow-release technology, we can not only increase the stability of each active component, but also prolong the reaction time, which can be applied to many fields of environmental governance.

[0004] Chinese patent document CN110387242A discloses a potassium permanganate sustained-release agent and its preparation method and application. The sustained-release agent is prepared by paraffin, quartz sand, activated carbon and potassium permanganate. However, the sustained-release material uses paraffin as a curing agent, and improper use may easily cause excessive petroleum hydrocarbons in soil or groundwater. Chinese patent document CN115677009A discloses a persulfate sustained-release material and a preparation method thereof, wherein persulfate beads are prepared from persulfate and clay minerals, and then coated with polylactic acid uniformly dispersed with inorganic salt particles. The persulfate beads prepared by this method have uneven composition, and the persulfate content contained in each persulfate bead is greatly affected by the operation. Moreover, the embedding agent pores and pores of the persulfate sustained-release material prepared by this method are disordered, and it cannot be guaranteed that all persulfate can be released or the release process is large or small. In addition, it uses polylactic acid as the coating liquid, which has the defect of incomplete coating and repeated coating, and usually requires repeated coating, which further affects the release performance of the sustained-release agent. Moreover, the pores formed by the inorganic salt are poor in effect and easy to collapse. Summary of the invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the defects of poor release performance and easy collapse of existing sustained-release materials, thereby providing a cellulose-coated sustained-release oxidant and a preparation method thereof that solves the above problems.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A method for preparing a cellulose-coated slow-release oxidant, comprising:

[0008] Obtaining polymer gel: grinding a dispersant and an oxidant to obtain a dispersant / oxidant complex, mixing a natural polymer material with a solvent to prepare a natural polymer material solution, adding an activator, a cross-linking agent, and a dispersant / oxidant complex to the natural polymer material solution and allowing the mixture to react to obtain a polymer gel;

[0009] Obtaining the coating solution: mixing natural cellulose with a solvent to prepare a natural cellulose solution, adding a second crosslinking agent, a pore-forming agent and a catalyst to the natural cellulose solution and stirring to react to obtain the coating solution;

[0010] The coating liquid is covered on the surface of the polymer gel, and then the surface is treated with acid immersion.

[0011] Preferably, the mass ratio of the natural polymer material, the activator, the cross-linking agent and the dispersant / oxidant complex is 1:(0.1-0.5):(0.5-1):1;

[0012] And / or, the mass ratio of the dispersant to the oxidant is 1:(2-10).

[0013] Preferably, the mass ratio of the natural cellulose, the second crosslinking agent, the pore former and the catalyst is 1:(0.03-0.1):(0.05-0.1):(0.1-0.5).

[0014] Preferably, the dispersant is at least one of illite, attapulgite and bentonite;

[0015] And / or, the oxidant is persulfate; the persulfate is sodium persulfate and / or potassium persulfate.

[0016] Preferably, the natural polymer material is sodium carboxymethyl cellulose and / or sodium carboxymethyl chitosan;

[0017] and / or, the concentration of the natural polymer material solution is 0.1 g / mL;

[0018] And / or, the solvent of the natural polymer material solution is at least one of water, ethanol and ammonia water.

[0019] Preferably, the activator is 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide;

[0020] The mass ratio of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride to N-hydroxysuccinimide is 2:1;

[0021] And / or, the cross-linking agent 1 is at least one of aminoguanidine hydrochloride, cystamine hydrochloride, and cystamine dihydrochloride.

[0022] Preferably, the natural cellulose is at least one of sawdust, straw, peanut shells, and bagasse;

[0023] and / or, the concentration of the natural cellulose solution is 0.1-0.2 g / mL;

[0024] And / or, the solvent of the natural cellulose solution is an ionic liquid; the ionic liquid is 1-allyl-3-methylimidazolium chloride or / and 1-butyl-3-methylimidazolium chloride;

[0025] And / or, the second cross-linking agent is at least one of succinaldehyde, glutaraldehyde, and glyoxal;

[0026] And / or, the pore-forming agent is nanocarbonate; the nanocarbonate is nano calcium carbonate or / and nano sodium carbonate;

[0027] And / or, the catalyst is natural iron ore powder; the natural iron ore powder is at least one of hematite powder, pyrite powder and siderite powder.

[0028] Preferably, the mass ratio of the polymer gel to the coating liquid is 1:(0.01-0.1);

[0029] And / or, the duration of the static reaction is ≥ 2 h;

[0030] And / or, after the static reaction, dialysis and freeze-drying are further performed;

[0031] And / or, the static reaction is carried out in a sealed environment at room temperature; the dialysis is carried out by placing the sample in an 8000 Da dialysis bag and dialyzing it with deionized water for 1 day;

[0032] And / or, the preparation process of the natural iron ore powder is: processing the natural iron ore in a planetary ball mill at a ball-to-material ratio of 10:1 at a speed of 600 rpm / min for 60 min, and passing through a 200-mesh sieve to obtain the powder;

[0033] And / or, the stirring reaction time is ≥ 1 h;

[0034] And / or, the covering method is spraying, dipping, or brushing.

[0035] Preferably, in the acid soaking treatment, the acid is an inorganic acid; the acid is at least one of hydrochloric acid, sulfuric acid, and nitric acid; the concentration of the acid is 0.1-1 mol / L; the acid soaking treatment time is ≥10 min;

[0036] And / or, the acid soaking treatment is followed by alcohol washing and freeze drying;

[0037] And / or, the grinding is ball milling; in the ball milling, the ball-to-material ratio is 20:1, the rotation speed of the ball mill is 400 rpm / min, and the ball milling time is 30 min; after the grinding, the material is screened, and the screen mesh is 200 mesh;

[0038] And / or, the dispersant / oxidant complex is further sieved, and the sieve mesh is 200 mesh;

[0039] And / or, the natural cellulose is natural cellulose treated with alkali; the alkali treatment comprises: crushing and sieving the natural cellulose, and then soaking it with alkali; the alkali is at least one of sodium hydroxide and potassium hydroxide; the concentration of the alkali is 20-50 g / L; the duration of the alkali soaking treatment is ≥90 min; and filtering, washing and drying are performed after the alkali soaking treatment.

[0040] The present invention also provides a cellulose coated slow-release oxidant, which is prepared by the above-mentioned preparation method of the cellulose coated slow-release oxidant.

[0041] The technical solution of the present invention has the following advantages:

[0042] 1. A method for preparing a cellulose coated slow-release oxidant, comprising: obtaining a polymer gel: grinding a dispersant and an oxidant to obtain a dispersant / oxidant complex, mixing a natural polymer material with a solvent to prepare a natural polymer material solution, adding an activator, a first cross-linking agent, and a dispersant / oxidant complex to the natural polymer material solution and allowing the solution to react to obtain a polymer gel; obtaining a coating liquid: mixing natural cellulose with a solvent to prepare a natural cellulose solution, adding a second cross-linking agent, a pore-forming agent, and a catalyst to the natural cellulose solution and stirring to obtain a coating liquid; covering the coating liquid on the surface of the polymer gel, and then subjecting the solution to an acid soaking treatment to obtain the coating liquid. The present invention uses natural polymer materials as embedding agents, prepares gels through graft polymerization of natural polymer materials, and then plays an embedding role on oxidants. A complex of oxidants and dispersants is added before forming the gel to ensure that the oxidants are evenly dispersed in the gel; naturally degradable cellulose is used as a coating agent, which forms a network structure through a cross-linking agent, and the pore-forming agent used forms a controllable release channel on the coating, which is conducive to the slow release of the oxidants; therefore, the oxidants prepared by the present invention have the advantages of many channels, small pores, and good release effects, which improves the effective utilization rate of the oxidants. At the same time, by mixing and adding the oxidants and dispersants, the hardness and stability of the sustained-release material are increased, and the safety during use is also significantly improved;

[0043] In addition, the present invention is simple to operate and easy to implement, and the prepared cellulose-coated slow-release oxidant has the advantages of high safety, low cost, good coating effect, and controllable release efficiency. Therefore, it can release the oxidant for a long time and has a good treatment effect on groundwater pollution, especially difficult-to-treat organic pollutants.

[0044] 2. In the preparation method of the cellulose coated slow-release oxidant provided by the present invention, natural iron ore powder is added to the coating liquid used, and when the persulfate is dissolved and released, it passes through the channel containing iron ions, and its oxidation effect is stronger, and the utilization rate of the persulfate is higher; the pore-forming agent used in the coating liquid is preferably nano-carbonate, and when the slow-release oxidant sprayed with the coating liquid is added with acid solution, the carbonate and the acid solution react to form carbon dioxide, thereby forming pores on the slow-release oxidant for various gases to pass through, and the pores are dense, strong, not easy to collapse, and controllable.

[0045] 3. The preparation method of the cellulose coated slow-release oxidant provided by the present invention uses a coating solution that can be coated successfully once without repeated coating; in addition, the coating solution used is formed by dissolving natural cellulose in an ionic liquid, which is more environmentally friendly, simple, and easy to operate, and the ionic liquid can be recycled.

[0046] 4. In the preparation method of the cellulose coated slow-release oxidant provided by the present invention, the shape of the prepared slow-release oxidant is controllable. After forming a gel and freeze-drying, it can be artificially formed into powder, sphere, block, cake, etc., and then coated; when it is used for in-situ chemical oxidation remediation of groundwater pollution, it is preferably a sphere with a small particle size, which is more conducive to injection; when the slow-release oxidant is used as a filling material for a permeable reaction wall (PRB), it is preferably a block, which is easier to replace, that is, the present invention can adjust the shape of the prepared slow-release oxidant according to different application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0048] Figure 1 is a graph showing the change in the concentration of persulfate released by the cellulose-coated slow-release oxidant obtained in Example 1-2 of the present invention over time;

[0049] Figure 2 It is a graph showing the change of tetracycline concentration over time in the cellulose coating slow-release oxidant repair experiment obtained in Examples 1-5 of the present invention and Comparative Example 1. DETAILED DESCRIPTION

[0050] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0051] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0052] Example 1

[0053] This embodiment provides a method for preparing a cellulose-coated slow-release oxidant, comprising the following steps:

[0054] 1) Weigh 5 g illite and 10 g sodium persulfate, and then add them into a planetary ball mill at a ball-to-material ratio of 20:1, wherein the speed of the ball mill is 400 rpm / min, the ball milling time is 30 min, and then pass through a 200 mesh sieve to obtain an illite / sodium persulfate composite;

[0055] 2) Weigh 5 g of sodium carboxymethyl cellulose and dissolve it in 50 mL of deionized water, then add 0.6 g of an activator, which is a mixture of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) (the mass ratio of EDC to NHS is 2:1), stir for 10 min, then add 2.5 g of aminoguanidine hydrochloride and 5 g of the illite / sodium persulfate complex prepared in step 1), continue stirring for 20 min, and seal and stand at room temperature for 2 h to form a hydrogel, which is placed in a dialysis bag with a cut-off molecular weight of 8000 Da, dialyzed with deionized water for 1 d, and freeze-dried with a freeze dryer to obtain a polymer gel;

[0056] 3) Processing the natural hematite in a planetary ball mill at a ball-to-material ratio of 10:1 at a speed of 600 rpm / min for 60 min, and passing through a 200-mesh sieve to obtain hematite powder;

[0057] 4) Crush the sawdust, pass it through a 100-mesh sieve, weigh 10 g of sawdust, add it to 100 mL of 40 g / L NaOH solution, stir and react for 90 min, then filter and wash with water until neutral, dry in a 40°C oven for 12 h, take 10 g of alkali-treated sawdust and add it to 50 mL of 1-allyl-3-methylimidazolium chloride, stir at 100°C for 2 h to obtain a transparent solution, then add 0.5 g of butanedial and continue stirring for 1 h, finally add 0.5 g of nano-calcium carbonate and 1 g of hematite powder obtained in step 3), stir for 10 min to obtain a coating solution;

[0058] 5) Spray 0.1 g of the coating liquid prepared in step 4) evenly on 10 g of the polymer gel prepared in step 2), soak it in 0.5 mol / L hydrochloric acid solution and stir it for 10 min after cooling, filter it, wash it with ethanol, and freeze-dry it to obtain a cellulose coated sustained-release oxidant.

[0059] Example 2

[0060] The difference between this embodiment and embodiment 1 is that the amount of nano calcium carbonate used is 1 g, and the rest is the same as embodiment 1.

[0061] Example 3

[0062] This embodiment provides a method for preparing a cellulose-coated slow-release oxidant, comprising the following steps:

[0063] 1) Weigh 1 g of attapulgite and 6 g of sodium persulfate, and then add them into a planetary ball mill at a ball-to-material ratio of 20:1, wherein the speed of the ball mill is 400 rpm / min, the ball milling time is 30 min, and then pass through a 200-mesh sieve to obtain an attapulgite / sodium persulfate composite;

[0064] 2) Weigh 5 g of sodium carboxymethyl chitosan and dissolve it in 50 mL of ethanol, then add 0.5 g of an activator, which is a mixture of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) (the mass ratio of EDC to NHS is 2:1), stir for 10 min, then add 4 g of cystamine hydrochloride and 5 g of the attapulgite / sodium persulfate complex prepared in step 1), continue stirring for 20 min, and seal and stand at room temperature for 3 h to form a hydrogel, which is placed in a dialysis bag with a cut-off molecular weight of 8000 Da, dialyzed with deionized water for 1 d, and freeze-dried with a freeze dryer to obtain a polymer gel;

[0065] 3) natural pyrite was processed in a planetary ball mill at a ball-to-material ratio of 10:1 at a speed of 600 rpm / min for 60 min, and passed through a 200-mesh sieve to obtain hematite powder;

[0066] 4) Crush the peanut shells, pass through a 100-mesh sieve, weigh 10 g of the peanut shells, add them to 100 mL of 20 g / L NaOH solution, stir and react for 90 min, then filter and wash with water until neutral, dry in a 40°C oven for 12 h, take 10 g of alkali-treated peanut shells and add them to 75 mL of 1-allyl-3-methylimidazole chloride, stir at 100°C for 2 h to obtain a transparent solution, then add 0.3 g of glutaraldehyde and continue stirring for 1 h, finally add 0.5 g of nano sodium carbonate and 3 g of pyrite powder obtained in step 3), stir for 10 min to obtain a coating solution;

[0067] 5) Spray 0.5 g of the coating liquid prepared in step 4) evenly on 10 g of the polymer gel prepared in step 2), soak it in 0.1 mol / L sulfuric acid solution and stir it for 10 min after cooling, filter it, wash it with ethanol, and freeze-dry it to obtain a cellulose coated slow-release oxidant.

[0068] Example 4

[0069] This embodiment provides a method for preparing a cellulose-coated slow-release oxidant, comprising the following steps:

[0070] 1) Weigh 1 g of bentonite and 6 g of potassium persulfate, and then add them into a planetary ball mill at a ball-to-material ratio of 20:1, wherein the speed of the ball mill is 400 rpm / min, the ball milling time is 30 min, and then pass through a 200-mesh sieve to obtain a bentonite / potassium persulfate composite;

[0071] 2) Weigh 5 g of sodium carboxymethyl cellulose and dissolve it in 50 mL of ammonia water, then add 2.5 g of an activator, which is a mixture of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) (the mass ratio of EDC to NHS is 2:1), stir for 10 min, then add 5 g of cystamine dihydrochloride and 5 g of the bentonite / potassium persulfate complex prepared in step 1), continue stirring for 20 min, and seal and stand at room temperature for 3 h to form a hydrogel, which is placed in a dialysis bag with a cut-off molecular weight of 8000 Da, dialyzed with deionized water for 1 d, and freeze-dried with a freeze dryer to obtain a polymer gel;

[0072] 3) Processing the natural siderite in a planetary ball mill at a ball-to-material ratio of 10:1 at a speed of 600 rpm / min for 60 min, and passing through a 200-mesh sieve to obtain hematite powder;

[0073] 4) Crush the straw, pass it through a 100-mesh sieve, weigh 10 g of the straw, add it to 100 mL of 50 g / L KOH solution, stir and react for 90 min, then filter and wash with water until neutral, dry it in a 40°C oven for 12 h, take 10 g of the alkali-treated straw and add it to 100 mL of 1-butyl-3-methylimidazolium chloride, stir it at 100°C for 2 h to obtain a transparent solution, then add 0.5 g of glyoxal and continue stirring for 1 h, finally add 0.5 g of nano sodium carbonate and 5 g of the siderite powder obtained in step 3), stir for 10 min to obtain a coating solution;

[0074] 5) Evenly immerse 1 g of the coating solution prepared in step 4) on 10 g of the polymer gel prepared in step 2), soak it in 1 mol / L nitric acid solution and stir it for 20 min after cooling, filter it, wash it with ethanol, and freeze-dry it to obtain a cellulose coated slow-release oxidant.

[0075] Example 5

[0076] This embodiment provides a method for preparing a cellulose-coated slow-release oxidant, comprising the following steps:

[0077] 1) Weigh 1 g of bentonite and 10 g of potassium persulfate, and then add them into a planetary ball mill at a ball-to-material ratio of 20:1, wherein the speed of the ball mill is 400 rpm / min, the ball milling time is 30 min, and then pass through a 200-mesh sieve to obtain a bentonite / potassium persulfate composite;

[0078] 2) Weigh 5 g of sodium carboxymethyl chitosan and dissolve it in 50 mL of ammonia water, then add 2 g of an activator, which is a mixture of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) (the mass ratio of EDC to NHS is 2:1), stir for 10 min, then add 5 g of cystamine dihydrochloride and 5 g of the bentonite / potassium persulfate complex prepared in step 1), continue stirring for 20 min, and let stand at room temperature for 3 h to form a hydrogel, which is placed in a dialysis bag with a molecular weight cutoff of 8000 Da, dialyzed with deionized water for 1 d, and freeze-dried with a freeze dryer to obtain a polymer gel;

[0079] 3) Processing the natural siderite in a planetary ball mill at a ball-to-material ratio of 10:1 at a speed of 600 rpm / min for 60 min, and passing through a 200-mesh sieve to obtain hematite powder;

[0080] 4) crush the bagasse, pass it through a 100-mesh sieve, weigh 10 g of the bagasse, add it to 100 mL of 20 g / L KOH solution, stir and react for 120 min, then filter and wash with water until neutral, dry it in a 40°C oven for 12 h, take 10 g of alkali-treated bagasse and add it to 50 mL of 1-butyl-3-methylimidazolium chloride, stir it at 100°C for 2 h to obtain a transparent solution, then add 1 g of glyoxal and continue stirring for 1 h, finally add 0.5 g of nano sodium carbonate and 3 g of the siderite powder obtained in step 3), stir for 10 min to obtain a coating solution;

[0081] 5) Evenly apply 1 g of the coating solution prepared in step 4) on 10 g of the polymer gel prepared in step 2), soak it in 0.5 mol / L nitric acid solution and stir it for 20 min after cooling, filter it, wash it with ethanol, and freeze-dry it to obtain a cellulose coated slow-release oxidant.

[0082] Comparative Example 1

[0083] The difference between this comparative example and Example 1 is that in the step of obtaining the polymer gel, the dispersant and the oxidant are not ground to obtain the dispersant / oxidant complex, and all the raw materials are directly mixed and allowed to react to obtain the polymer gel. Other conditions are the same as in Example 1.

[0084] Test Example 1

[0085] The cellulose coated slow-release oxidant prepared in Examples 1-2 was subjected to a static release test. The test steps were as follows: 5 g of the cellulose coated slow-release oxidant prepared in Examples 1 and 2 were placed in a 500 mL beaker, 250 mL of water was added, 100 μL of the test solution was taken at different time intervals, and a mixed solution (4 g / L NaHCO 3 , 80 g / L KI) to 10 mL, shake the reaction for 15 min, measure the absorbance of persulfate at 352 nm, calculate its concentration, and the concentration of sodium persulfate changes with time. Figure 1 shown; according to Figure 1 It can be seen that the release rate of persulfate is related to the dosage of the pore-forming agent. The higher the dosage of the pore-forming agent, the faster the release rate of persulfate.

[0086] Test Example 2

[0087] The cellulose coated slow-release oxidant prepared in Examples 1-5 and Comparative Example 1 was used for the repair experiment. The experimental steps were as follows: 5 g of the cellulose coated slow-release oxidant prepared in Examples 1-5 and Comparative Example 1 were weighed and placed in a 500 mL beaker, 250 mL of contaminated water was added, and the tetracycline content in the contaminated water was 20 mg / L. 1 mL of the test solution was taken at intervals, and the tetracycline concentration in the sample was measured at 352 nm by ultraviolet spectrophotometry. The change of tetracycline concentration over time was as follows: Figure 2 shown; according to Figure 2 It can be seen that the cellulose coated slow-release oxidant prepared in comparative example 1 reaches the oxidation equilibrium effect in a very short time and has poor slow-release performance, while the cellulose coated slow-release oxidants prepared in embodiments 1-5 of the present invention all have excellent oxidation effects and good release performance, providing a new repair material for in-situ groundwater remediation.

[0088] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A method for preparing a cellulose-coated slow-release oxidant, It is characterized in that include: Obtaining polymer gel: grinding a dispersant and an oxidant to obtain a dispersant / oxidant complex, mixing a natural polymer material with a solvent to prepare a natural polymer material solution, adding an activator, a cross-linking agent, and a dispersant / oxidant complex to the natural polymer material solution and allowing the mixture to react to obtain a polymer gel; The oxidant is persulfate; Obtaining the coating solution: mixing natural cellulose with a solvent to prepare a natural cellulose solution, adding a second crosslinking agent, a pore-forming agent and a catalyst to the natural cellulose solution and stirring to react to obtain the coating solution; The coating liquid is covered on the surface of the polymer gel, and then the surface is treated with acid immersion.

2. The preparation method according to claim 1, It is characterized in that The mass ratio of the natural polymer material, the activator, the cross-linking agent and the dispersant / oxidant complex is 1:(0.1-0.5):(0.5-1):

1.

3. The preparation method according to claim 1, It is characterized in that The mass ratio of the dispersant to the oxidant is 1:(2-10).

4. The preparation method according to claim 1, It is characterized in that The mass ratio of the natural cellulose, the second crosslinking agent, the pore former and the catalyst is 1:(0.03-0.1):(0.05-0.1):(0.1-0.5).

5. The preparation method according to claim 1, It is characterized in that The dispersant is at least one of illite, attapulgite and bentonite.

6. The preparation method according to claim 1, It is characterized in that The persulfate is sodium persulfate and / or potassium persulfate.

7. The preparation method according to claim 1, It is characterized in that The natural polymer material is sodium carboxymethyl cellulose and / or sodium carboxymethyl chitosan.

8. The preparation method according to claim 1, It is characterized in that The concentration of the natural polymer material solution is 0.1 g / mL.

9. The preparation method according to claim 1, It is characterized in that The solvent of the natural polymer material solution is at least one of water, ethanol and ammonia water.

10. The preparation method according to claim 1, It is characterized in that The activating agents are 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide; The mass ratio of the 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride to N-hydroxysuccinimide is 2:

1.

11. The preparation method according to claim 1, It is characterized in that The first cross-linking agent is at least one of aminoguanidine hydrochloride, cystamine hydrochloride, and cystamine dihydrochloride.

12. The preparation method according to claim 1, It is characterized in that The natural cellulose is at least one of wood chips, straw, peanut shells and bagasse.

13. The preparation method according to claim 1, It is characterized in that The concentration of the natural cellulose solution is 0.1-0.2 g / mL.

14. The preparation method according to claim 1, It is characterized in that The solvent of the natural cellulose solution is an ionic liquid; the ionic liquid is 1-allyl-3-methylimidazolium chloride and / or 1-butyl-3-methylimidazolium chloride.

15. The preparation method according to claim 1, It is characterized in that The second cross-linking agent is at least one of succinaldehyde, glutaraldehyde and glyoxal.

16. The preparation method according to claim 1, It is characterized in that The pore-forming agent is nano-carbonate; the nano-carbonate is nano-calcium carbonate and / or nano-sodium carbonate.

17. The preparation method according to claim 1, It is characterized in that The catalyst is natural iron ore powder; the natural iron ore powder is at least one of hematite powder, pyrite powder and siderite powder.

18. The preparation method according to claim 1, It is characterized in that The mass ratio of the polymer gel to the coating liquid is 1:(0.01-0.1).

19. The preparation method according to claim 1, It is characterized in that The duration of the static reaction is ≥2 h.

20. The preparation method according to claim 1, It is characterized in that After the static reaction, dialysis and freeze-drying are further performed.

21. The preparation method according to claim 1, It is characterized in that The stirring reaction time is ≥ 1 h.

22. The preparation method according to claim 1, It is characterized in that The covering method is spraying, dipping, or brushing.

23. The preparation method according to claim 1, It is characterized in that In the acid soaking treatment, the acid is an inorganic acid; the acid is at least one of hydrochloric acid, sulfuric acid, and nitric acid; the concentration of the acid is 0.1-1 mol / L; and the acid soaking treatment duration is ≥10 min.

24. The preparation method according to claim 1, It is characterized in that The acid soaking treatment is followed by alcohol washing and freeze drying.

25. The preparation method according to claim 1, It is characterized in that The grinding is ball milling.

26. The preparation method according to claim 1, It is characterized in that The dispersant / oxidant composite is also screened.

27. The preparation method according to claim 1, It is characterized in that The natural cellulose is natural cellulose treated with alkali; the alkali treatment comprises: crushing and sieving the natural cellulose, and then soaking it with alkali; the alkali is at least one of sodium hydroxide and potassium hydroxide; the concentration of the alkali is 20-50 g / L; the duration of the alkali soaking treatment is ≥90 min; and after the alkali soaking treatment, filtering, washing and drying are performed.

28. A cellulose-coated slow-release oxidant, It is characterized in that The invention is prepared by the method for preparing the cellulose coated slow-release oxidant according to any one of claims 1 to 27.

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