Preparation method and application of gel-type sodium bisulfite activated potassium permanganate slow-release composite agent taking silica sol as carrier

Abstract

The application relates to a preparation method and application of a gel-type sodium bisulfite activated potassium permanganate slow-release composite medicament taking silica sol as a carrier, and relates to the technical field of pollution treatment and environmental remediation. In order to solve the problems that the traditional active free radical oxidation treatment mode usually has instantaneous release of oxidants, self-quenching of free radicals, and difficulty in continuously controlling reaction, and that excessively high instantaneous concentration of free radicals leads to excessive oxidation reaction, the slow-release composite medicament dissolves potassium permanganate and sodium bisulfite into silica sol, utilizes the double-layer compression effect induced by electrolytes and the particle aggregation caused by van der Waals force to form a three-dimensional gel network structure, fixes water molecules and the two medicaments in the gel network structure, and due to the osmotic pressure in water, the medicament molecules will gradually dissolve into water, and finally, slow-release control of the medicaments is realized. The application can obtain a preparation method and application of a gel-type sodium bisulfite activated potassium permanganate slow-release composite medicament taking silica sol as a carrier.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pollution control and environmental remediation, and particularly relates to a preparation method and application of a gel-type sodium bisulfite-activated potassium permanganate slow-release composite reagent taking silica sol as a carrier. BACKGROUND

[0002] With the rapid development of modern industry and agriculture, the safety of surface water environment has been greatly challenged and threatened. Pollutants such as refractory organic matter, heavy metals and microorganisms often exist in water sources, which seriously threaten the safety of drinking water for human beings. Therefore, safe, effective and sustained water treatment reagents have become the focus of research. In the process of water treatment, potassium permanganate is a commonly used pre-treatment oxidant, which can remove organic pollutants in water through strong oxidation and reduce the difficulty of subsequent process treatment.

[0003] In recent years, with in-depth research, it has been found that the use of sodium bisulfite to activate potassium permanganate can significantly improve the oxidation capacity and reaction rate of potassium permanganate. At the same time, sodium bisulfite can hydrolyze to generate sulfite ions, which act as reducing agents to participate in the reaction and generate more active free radicals with strong oxidation, proving that the above-mentioned activation method not only improves the removal efficiency of pollutants, but also achieves more thorough degradation, effectively dealing with complex pollutants.

[0004] However, the traditional active free radical oxidation treatment method usually has the disadvantages of instantaneous release of oxidant, self-quenching of free radicals and difficulty in sustained control of reaction. At the same time, the excessively high instantaneous concentration of free radicals will lead to excessive oxidation reaction, which not only increases the cost, but also may produce by-products, causing secondary pollution to water bodies. SUMMARY

[0005] The purpose of the present application is to solve the above technical problems, and provide a preparation method and application of a gel-type sodium bisulfite-activated potassium permanganate slow-release composite reagent taking silica sol as a carrier.

[0006] A preparation method of a gel-type sodium bisulfite-activated potassium permanganate slow-release composite reagent taking silica sol as a carrier, which is carried out according to the following steps:

[0007] Step S1, preparation of potassium permanganate slow-release gel:

[0008] Potassium permanganate is added to a silica sol solution, and after stirring uniformly, a mixed solution a is obtained; a syringe is used to suck the mixed solution a and inject it into a hemispherical silica gel mold, and after solidification, the mold is removed to obtain a potassium permanganate slow-release gel;

[0009] Step S2, preparation of sodium bisulfite slow-release gel:

[0010] Sodium bisulfite is added to the silica sol solution, and after stirring, a mixed solution b is obtained; the mixed solution b is sucked by using a syringe and injected into a semi-spherical silica gel mold, and after solidification, the sodium bisulfite slow-release gel is demolded;

[0011] Step S3, preparing a slow-release composite medicament sphere:

[0012] The potassium permanganate slow-release gel obtained in step S1 is adhered to the sodium bisulfite slow-release gel obtained in step S2 by using silicone glue, to obtain a gel-type sodium bisulfite activated potassium permanganate slow-release composite medicament sphere with silica sol as a carrier; the molar ratio of potassium permanganate in the potassium permanganate slow-release gel to sodium bisulfite in the sodium bisulfite slow-release gel is (1:2.5), (1:5) or (1:10).

[0013] The application of a gel-type sodium bisulfite activated potassium permanganate slow-release composite medicament with silica sol as a carrier, wherein the gel-type sodium bisulfite activated potassium permanganate slow-release composite medicament with silica sol as a carrier is applied to remove algae or refractory organic pollutants in drinking water.

[0014] Principle of the present application:

[0015] The present application develops a slow-release composite water treatment medicament which is safe, effective and has a sustained treatment effect for the front end of drinking water treatment. Silica sol is a colloidal solution in which nano-sized silicon dioxide particles are uniformly dispersed and suspended in water. The size of these silicon dioxide particles is usually between 1-100 nm, so silica sol has certain colloidal properties. The silicon dioxide particles in silica sol are usually amorphous (non-crystalline) and have a negative charge. After adding a certain amount of Na + , K + salt ions, positive ions are attracted to the silicon dioxide particles due to the action of electrostatic force. These metal ions neutralize or reduce the negative charge on the surface of the silicon dioxide particles through electrostatic adsorption, the repulsive force between the silicon dioxide particles decreases, the time interval between them becomes smaller, and the van der Waals force begins to dominate. Ultimately, the silicon dioxide particles gradually aggregate with each other, forming a three-dimensional network structure of gel. The two medicament molecules and water molecules are trapped inside the gel by the network structure to form a slow-release composite medicament. When the slow-release composite medicament is put into water, the surface layer of the medicament is dissolved first and carried away by the water flow, and the inner layer of the medicament gradually dissolves and seeps out under the action of osmotic pressure, ultimately achieving the purpose of slow and controllable release, and improving the sustainability of water purification.

[0016] Advantages of the present application:

[0017] (1) The present application utilizes the intermediate valence manganese and high activity free radicals generated by sodium bisulfite activated potassium permanganate to oxidatively degrade organic pollutants in water. The slow-release gel is used to slow down the release speed of the oxidant, and by controlling the transient concentration of active species, the phenomenon of excessive oxidation is reduced, which not only improves the utilization efficiency of the reagent and reduces the cost of raw materials, but also avoids the problem of pollution caused by the release of algae cell contents in natural water bodies due to excessive oxidation.

[0018] (2) The present application has low raw material cost and simple preparation process. The silica sol is a green and safe reagent in the environmental field and harmless to soil and water environment. Its main component is silicon dioxide, which can be recycled and reused after forming a gel and releasing the internal reagent. Sodium bisulfite and potassium permanganate are common chemical reagents in water treatment, and the newly formed manganese dioxide is in the form of floc, which can be removed in the subsequent coagulation and sedimentation process and has no negative impact on drinking water safety.

[0019] (3) The slow-release composite reagent of the present application uses silica sol as a carrier, dissolves potassium permanganate and sodium bisulfite into the silica sol, uses the double-layer compression effect induced by electrolyte and the particle aggregation caused by van der Waals force to finally form a three-dimensional gel network structure, and fixes water molecules and the two reagents in the gel network structure. Due to the osmotic pressure in water, the reagent molecules will gradually dissolve into water, and finally realize the slow release control of the reagent.

[0020] (4) The present application can prepare a slow-release composite reagent with reliable performance, safety and high efficiency, which not only has low cost but also has high pollutant removal efficiency, and is a new type of drinking water pretreatment reagent.

[0021] The present application can obtain a preparation method and application of a gel-type sodium bisulfite activated potassium permanganate slow-release composite reagent using silica sol as a carrier. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The figure shows the preparation process of the gel-type sodium bisulfite activated potassium permanganate slow-release composite reagent using silica sol as a carrier of the present application;

[0023] Figure 2 The figure shows the schematic diagram of simulating the treatment of contaminated wastewater in the laboratory conditions of the present application;

[0024] Figure 3 The figure shows the degradation effect of the gel-type sodium bisulfite activated potassium permanganate slow-release composite reagent using silica sol as a carrier prepared in Examples 1-3 on bisphenol A. DETAILED DESCRIPTION

[0025] Embodiment 1: A preparation method of a gel-type sodium bisulfite-activated potassium permanganate slow-release composite agent with silica sol as a carrier, which is carried out according to the following steps:

[0026] Step S1, preparation of a potassium permanganate slow-release gel:

[0027] Potassium permanganate is added to a silica sol solution, and after uniform stirring, a mixed solution a is obtained; a syringe is used to suck the mixed solution a and inject it into a hemispherical silica gel mold, and after solidification, the mold is removed to obtain a potassium permanganate slow-release gel;

[0028] Step S2, preparation of a sodium bisulfite slow-release gel:

[0029] Sodium bisulfite is added to a silica sol solution, and after uniform stirring, a mixed solution b is obtained; a syringe is used to suck the mixed solution b and inject it into a hemispherical silica gel mold, and after solidification, the mold is removed to obtain a sodium bisulfite slow-release gel;

[0030] Step S3, preparation of a slow-release composite agent sphere:

[0031] The potassium permanganate slow-release gel obtained in step S1 and the sodium bisulfite slow-release gel obtained in step S2 are adhered together using silicone glue to obtain a gel-type sodium bisulfite-activated potassium permanganate slow-release composite agent sphere with silica sol as a carrier; the molar ratio of potassium permanganate in the potassium permanganate slow-release gel to sodium bisulfite in the sodium bisulfite slow-release gel is (1:2.5), (1:5), or (1:10).

[0032] Embodiment 2: The difference between this embodiment and embodiment 1 is that the mass of the potassium permanganate to the volume of the silica sol solution in step S1 is (0.316-0.632) g: 20 mL.

[0033] The other steps are the same as those in embodiment 1.

[0034] Embodiment 3: The difference between this embodiment and embodiment 1 or 2 is that after the mixed solution a is injected into the hemispherical silica gel mold in step S1, it is solidified at a temperature of 25-30°C for 12-24 h before the mold is removed. If it is not used immediately, it is sealed and stored in a 4°C refrigerator.

[0035] The other steps are the same as those in embodiment 1 or 2.

[0036] Embodiment 4: The difference between this embodiment and any one of embodiments 1-3 is that the mass of the sodium bisulfite to the volume of the silica sol solution in step S2 is (1.04-4.16) g: 20 mL.

[0037] The other steps are the same as those in embodiments 1-3.

[0038] The difference between the embodiment and the first to fourth embodiments is that the mixed solution b is injected into the semi-spherical silica gel mold in step S2, and then the mold is demolded after being solidified at a temperature of 25-30℃ for 12-24h. If not used immediately, the mold is sealed and stored in a 4℃ refrigerator.

[0039] The other steps are the same as the first to fourth embodiments.

[0040] The difference between the embodiment and the first to fifth embodiments is that the mass fraction of the silica sol in the silica sol solution in steps S1 and S2 is 19-41%.

[0041] The other steps are the same as the first to fifth embodiments.

[0042] The difference between the embodiment and the first to sixth embodiments is that a magnetic stirrer is used for stirring in steps S1 and S2.

[0043] The other steps are the same as the first to sixth embodiments.

[0044] The difference between the embodiment and the first to seventh embodiments is that the volume of the mixed solution a and the mixed solution b drawn in steps S1 and S2 is 1mL, 2mL, 3mL or 4mL.

[0045] The other steps are the same as the first to seventh embodiments.

[0046] The difference between the embodiment and the first to eighth embodiments is that the diameter of the gel-type sodium bisulfite activated potassium permanganate slow-release composite agent sphere in step S2 is 1.56-2.48cm.

[0047] The other steps are the same as the first to eighth embodiments.

[0048] The tenth embodiment is an application of a gel-type sodium bisulfite activated potassium permanganate slow-release composite agent with silica sol as a carrier. The gel-type sodium bisulfite activated potassium permanganate slow-release composite agent with silica sol as a carrier is applied to remove algae and refractory organic pollutants in surface water and remove pesticides and refractory organic pollutants in soil.

[0049] The effective oxidizing components of the gel-type sodium bisulfite activated potassium permanganate slow-release composite agent are active manganese (RMnS), hydroxyl radicals (HO·) and sulfate radicals (SO4· -), mainly produced by the activation of potassium permanganate by sodium bisulfite. The first step of the reaction is the electron stealing from sodium bisulfite to generate Mn(Ⅵ) and SO3· - . Subsequently, Mn(Ⅵ) is further reduced to Mn(Ⅴ), Mn(Ⅳ), Mn(Ⅲ) and Mn(Ⅱ) under the action of HSO3 - , while a large amount of SO3· - is generated. Dissolved oxygen in water and SO3· - combine to generate SO5· - , SO5· - and HSO3 - react to generate SO4· - . Once SO4· - is generated in the system, it will generate HO· through the reaction with HO - / H2O, so RMnS, HO· and SO4· - are the main active species for degrading pollutants in the slow-release composite agent, and the specific reaction equations are as follows (1-1) to (1-8).

[0050] Mn (Ⅶ) + HSO3 - → Mn (Ⅵ) + SO3· - + H + (1-1)

[0051] Mn (Ⅵ) + HSO3 - → Mn (Ⅴ) + SO3· - + H + (1-2)

[0052] Mn (Ⅴ) + HSO3 - → Mn (Ⅳ) + SO3· - + H+ (1-3)

[0053] Mn (Ⅳ) + HSO3 - → Mn (Ⅲ) + SO3· - + H + (1-4)

[0054] Mn (Ⅲ) + HSO3 - → Mn(Ⅱ) + SO3· - + H + (1-5)

[0055] SO3· - + O2 → SO5· - (1-6)

[0056] SO5·- + HSO3 - → SO4· - + SO4 2- + H + (1-7)

[0057] SO4· - +HO - →SO4 2- +HO· (1-8).

[0058] The beneficial effects of the present application are verified by the following examples:

[0059] Example 1: A preparation method of a gel-type sodium bisulfite activated potassium permanganate slow-release composite agent taking silica sol as a carrier, which is carried out according to the following steps:

[0060] Step S1, preparation of a potassium permanganate slow-release gel:

[0061] 0.632 g of potassium permanganate is weighed and added to a conical flask containing 20 mL of silica sol (29-31%) and stirred using a magnetic stirrer until the potassium permanganate and silica sol are fully mixed and uniform, to obtain a mixed solution a; 2 mL of the mixed solution a is sucked using a syringe and injected into a hemispherical silica gel mold, and stored at a temperature of 28°C, and after 12 h of solidification, demolding is performed to obtain a hemispherical solid potassium permanganate slow-release gel, and the diameter of the sphere is about 1.97 cm;

[0062] Step S2, preparation of a sodium bisulfite slow-release gel:

[0063] 2.08 g of sodium bisulfite is weighed and added to a conical flask containing 20 mL of silica sol (29-31%) and stirred using a magnetic stirrer until the sodium bisulfite and silica sol are fully mixed and uniform, to obtain a mixed solution b; 2 mL of the mixed solution b is sucked using a syringe and injected into a hemispherical silica gel mold, and stored at a temperature of 28°C, and after 12 h of solidification, demolding is performed to obtain a hemispherical solid sodium bisulfite slow-release gel, and the diameter of the sphere is about 1.97 cm;

[0064] Step S3, preparation of a slow-release composite agent sphere:

[0065] The potassium permanganate slow-release gel obtained in step S1 and the sodium bisulfite slow-release gel obtained in step S2 are adhered together using silicone glue, and finally form a complete sphere, which is half potassium permanganate slow-release gel and the other half is sodium bisulfite slow-release gel, and the diameter of the sphere is about 1.97 cm; the molar ratio of the potassium permanganate in the potassium permanganate slow-release gel to the sodium bisulfite in the sodium bisulfite slow-release gel is 1:5;

[0066] Step S4, degradation experiment of model pollutant bisphenol A:

[0067] The slow-release composite agent obtained in step S3 was placed in the column of a fluidized bed reactor (as shown in Figure 2 The concentration of the bisphenol A solution was 0.5 μmmol / L, and the simulated wastewater was passed through the reaction column at a flow rate of 10 mL / min using a peristaltic pump. The concentration of bisphenol A in the solution after reaction was determined at different reaction times. The reaction temperature was room temperature (20.2°C), and the pH of the simulated wastewater was about 6.7.

[0068] Example 2: A preparation method of a gel-type sodium bisulfite activated potassium permanganate slow-release composite agent using silica sol as a carrier, which was performed according to the following steps:

[0069] Step S1, preparation of a potassium permanganate slow-release gel:

[0070] 0.632 g of potassium permanganate was weighed and added to a conical flask containing 20 mL of silica sol (29-31%). The mixture was stirred using a magnetic stirrer until the potassium permanganate and silica sol were fully mixed and uniform. Then, 2 mL of the mixture was taken using a syringe and injected into a hemispherical silica gel mold. The mold was stored at a temperature of 28°C, and the gel was demolded after 12 h of solidification to obtain a hemispherical solid potassium permanganate slow-release gel with a diameter of about 1.97 cm.

[0071] Step S2, preparation of a sodium bisulfite slow-release gel:

[0072] 4.16 g of sodium bisulfite was weighed and added to a conical flask containing 20 mL of silica sol (29-31%). The mixture was stirred using a magnetic stirrer until the sodium bisulfite and silica sol were fully mixed and uniform. Then, 2 mL of the mixture was taken using a syringe and injected into a hemispherical silica gel mold. The mold was stored at a temperature of 28°C, and the gel was demolded after 12 h of solidification to obtain a hemispherical solid sodium bisulfite slow-release gel with a diameter of about 1.97 cm.

[0073] Step S3, preparation of a slow-release composite agent sphere:

[0074] The potassium permanganate slow-release gel obtained in step S1 and the sodium bisulfite slow-release gel obtained in step S2 were adhered together using silicone glue to form a complete sphere. One half of the sphere was a potassium permanganate slow-release gel, and the other half was a sodium bisulfite slow-release gel. The diameter of the sphere was about 1.97 cm. The molar ratio of potassium permanganate in the potassium permanganate slow-release gel to sodium bisulfite in the sodium bisulfite slow-release gel was 1:10.

[0075] Step S4, degradation experiment of model pollutant bisphenol A:

[0076] The slow-release composite agent obtained in step S3 was placed in the column of a fluidized bed reactor (as shown in Figure 2 A solution of bisphenol A with a concentration of 0.5 μmmol / L was used as simulated wastewater, and a peristaltic pump was used to make the simulated wastewater pass through the reaction column at a flow rate of 10 mL / min. The concentration of bisphenol A in the solution after reaction was determined at different reaction times. The reaction temperature was room temperature (20.2°C), and the pH of the simulated wastewater was about 6.7.

[0077] Example 3: A preparation method of a slow-release composite agent of potassium permanganate activated by sodium bisulfite gel with silica sol as a carrier, which was performed according to the following steps:

[0078] Step S1: Preparation of a slow-release gel of potassium permanganate:

[0079] 0.632 g of potassium permanganate was weighed and added to a conical flask containing 20 mL of silica sol (29-31%). A magnetic stirrer was used to stir until the potassium permanganate and the silica sol were fully mixed and uniform. Then, 3 mL of the mixed solution a was taken by a syringe and injected into a hemispherical silica gel mold. The mold was stored at a temperature of 28°C, and the slow-release gel of potassium permanganate was demolded after 12 h of solidification to obtain a hemispherical solid slow-release gel of potassium permanganate with a diameter of about 2.25 cm.

[0080] Step S2: Preparation of a slow-release gel of sodium bisulfite:

[0081] 2.08 g of sodium bisulfite was weighed and added to a conical flask containing 20 mL of silica sol (29-31%). A magnetic stirrer was used to stir until the sodium bisulfite and the silica sol were fully mixed and uniform. Then, 3 mL of the mixed solution b was taken by a syringe and injected into a hemispherical silica gel mold. The mold was stored at a temperature of 28°C, and the slow-release gel of sodium bisulfite was demolded after 12 h of solidification to obtain a hemispherical solid slow-release gel of sodium bisulfite with a diameter of about 2.25 cm.

[0082] Step S3: Preparation of a slow-release composite agent ball:

[0083] The slow-release gel of potassium permanganate obtained in step S1 and the slow-release gel of sodium bisulfite obtained in step S2 were adhered together using silicone glue to form a complete ball. One half of the ball was the slow-release gel of potassium permanganate, and the other half was the slow-release gel of sodium bisulfite. The diameter of the ball was about 2.25 cm. The molar ratio of potassium permanganate in the slow-release gel of potassium permanganate to sodium bisulfite in the slow-release gel of sodium bisulfite was 1:5.

[0084] Step S4: Degradation experiment of model pollutant bisphenol A:

[0085] The slow-release composite agent obtained in step S3 was placed in the column of a fluidized bed reactor (as shown in Figure 2 The bisphenol A solution with a concentration of 0.5 μm mol / L was used as simulated wastewater, and the simulated wastewater was uniformly passed through the reaction column at a flow rate of 10 mL / min using a peristaltic pump. The bisphenol A concentration was determined by taking the post-reaction solution from the storage barrel at different reaction times. The reaction temperature was room temperature (20.2°C), and the pH of the simulated wastewater was about 6.7.

[0086] The degradation effect of bisphenol A in the above examples 1-3 is shown in Figure 3 It can be seen that the size of the slow-release composite agent and the amount of potassium permanganate and sodium bisulfite added have an effect on the degradation of bisphenol A. In example 1, the molar ratio of potassium permanganate to sodium bisulfite is 1:5, and the diameter of the slow-release composite agent is 1.97 cm. The degradation rate of bisphenol A reaches 58.8% in the first 5 minutes of the reaction.

[0087] In example 2, under the same diameter of the slow-release composite agent, a higher proportion (potassium permanganate: sodium bisulfite = 1:10) of sodium bisulfite is dissolved in large quantities in the initial stage of the reaction, and part of the generated oxidizing active species is consumed by the reducing agent itself, resulting in a bisphenol A degradation rate of only 29% in the first 5 minutes of the reaction. When the reaction proceeds to 60 minutes, the release of potassium permanganate and sodium bisulfite is stabilized in a reasonable concentration range due to the controlled release of the gel, and the degradation rate of bisphenol A by the composite agent increases to 81.8%, and the oxidation efficiency of the active species is fully utilized.

[0088] In example 3, the diameter of the slow-release composite agent is expanded to 2.25 cm, and the molar ratio of potassium permanganate to sodium bisulfite is 1:5. Efficient degradation of bisphenol A is observed. The degradation rate of bisphenol A is 100% from the 120th minute of the reaction to the 400th minute of the reaction, which is higher than that of example 1 (87.1%-96.7%) and example 2 (87.2%-97.3%). The above examples 1-3 show that the slow-release composite agent can quickly and effectively control the release of the internal agent in water, fully utilize the degradation efficiency of the oxidizing active species on pollutants, and larger slow-release composite agents show better removal effect on pollutants and longer pollution control time. Different specifications of slow-release composite agents can be used according to the actual application scene.

[0089] The gel-type sodium bisulfite activated potassium permanganate slow-release composite agent prepared in the above examples 1-3 has excellent water treatment performance, greatly improves the degradation efficiency of pollutants, and reduces the amount of agent used, which is an energy-saving, green and safe water treatment composite agent.

Claims

1. A method for preparing a gel-type sodium bisulfite-activated potassium permanganate sustained-release composite agent using silica sol as a carrier, characterized in that... The preparation method is carried out according to the following steps: Step S1, preparation of potassium permanganate slow-release gel: Potassium permanganate is added to the silica sol solution, and after uniform stirring, a mixed solution a is obtained; the mixed solution a is sucked by a syringe and injected into a hemispherical silica gel mold, and after solidification, the mold is removed to obtain a hemispherical solid potassium permanganate slow-release gel with a sphere diameter of 2.25 cm; Step S2, preparation of sodium bisulfite slow-release gel: Sodium bisulfite is added to the silica sol solution, and after uniform stirring, a mixed solution b is obtained; the mixed solution b is sucked by a syringe and injected into a hemispherical silica gel mold, and after solidification, the mold is removed to obtain a hemispherical solid sodium bisulfite slow-release gel with a sphere diameter of 2.25 cm; Step S3, preparation of slow-release composite agent sphere: The potassium permanganate slow-release gel obtained in step S1 and the sodium bisulfite slow-release gel obtained in step S2 are adhered together using silicone glue to obtain a gel-type sodium bisulfite activated potassium permanganate slow-release composite agent sphere with silica sol as a carrier, with a sphere diameter of 2.25 cm; the molar ratio of potassium permanganate in the potassium permanganate slow-release gel to sodium bisulfite in the sodium bisulfite slow-release gel is 1:5; and the gel-type sodium bisulfite activated potassium permanganate slow-release composite agent sphere with silica sol as a carrier is used in the degradation of bisphenol A.

2. A method for preparing a gel-type sodium bisulfite activated potassium permanganate slow-release composite agent using silica sol as a carrier according to claim 1, characterized in that The mass of the potassium permanganate in step S1 to the volume of the silica sol solution is (0.316-0.632) g:20 mL.

3. A method for preparing a gel-type sodium bisulfite activated potassium permanganate slow release composite agent using silica sol as a carrier according to claim 1, characterized in that After the mixed solution a in step S1 is injected into the hemispherical silica gel mold, it is solidified at a temperature of 25-30°C for 12-24 h, and then the mold is removed.

4. The method for preparing a gel-type sodium bisulfite activated potassium permanganate slow-release composite agent with silica sol as a carrier according to claim 1, characterized in that The mass of the sodium bisulfite in step S2 to the volume of the silica sol solution is (1.04-4.16) g:20 mL.

5. The method for preparing a gel-type sodium bisulfite activated potassium permanganate slow-release composite agent using silica sol as a carrier according to claim 1, characterized in that After the mixed solution b in step S2 is injected into the hemispherical silica gel mold, it is solidified at a temperature of 25-30°C for 12-24 h, and then the mold is removed.

6. The method for preparing a gel-type sodium bisulfite activated potassium permanganate slow-release composite agent with silica sol as a carrier according to claim 1, characterized in that The mass fraction of the silica sol in the silica sol solution in steps S1 and S2 is 19-41%.

7. The method for preparing a gel-type sodium bisulfite activated potassium permanganate slow-release composite agent with silica sol as a carrier according to claim 1, characterized in that In steps S1 and S2, a magnetic stirrer is used for stirring.

8. A method for preparing a gel-type sodium bisulfite activated potassium permanganate slow release composite agent using silica sol as a carrier according to claim 1, characterized in that The volume of the mixed solution a and the mixed solution b sucked in steps S1 and S2 is 1 mL, 2 mL, 3 mL or 4 mL.

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