A permanganate complexing agent and its use in water treatment

Abstract

The application discloses a permanganate composite agent and application thereof in water treatment, and belongs to the technical field of waste water treatment. The composite agent comprises granules A and granules B, the granule A is formed by loading potassium permanganate on activated carbon and then forming a base core with carbonates, and a mixture of polyferric sulfate, chitosan and sodium alginate forms an outer shell; the granule B is formed by loading sodium percarbonate and ascorbic acid on a porous carrier, and then coating the porous carrier with polyferric sulfate. After the granules are added, the chitosan in the outer shell of the granule A is protonated and swells under acidic conditions, accelerates the diffusion of H + CO2 micro-bubbles are generated in situ by reacting with carbonates, the internal pressure of the CO2 micro-bubbles promotes the rapid release of potassium permanganate from the pores of the activated carbon, and the pre-oxidation time is shortened to 10-15 minutes; the ascorbic acid in the granule B activates the sodium percarbonate to release H2O2 and generate ·OH, and the potassium permanganate forms a synergistic oxidation, which effectively degrades stubborn organic matters such as aniline and dye intermediates.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a permanganate composite agent and its application in water treatment. Background Technology

[0002] Water is the most precious natural resource for human survival and development. With the increasing scarcity of water resources, water pollution control has received growing attention. Wastewater treatment methods are mainly divided into physical, chemical, biological, and integrated treatment methods. Among these, integrated treatment methods are widely used due to their stable treatment effects and relatively controllable costs.

[0003] In integrated wastewater treatment processes, the application of water treatment agents is indispensable, especially in the treatment of biological wastewater effluent (which mainly contains pollutants such as color, COD, total phosphorus, and ammonia nitrogen). In these cases, water treatment agents are generally required for deep treatment in order to achieve compliant discharge or recycling.

[0004] Permanganate composite chemicals (PPC) are a type of water treatment pre-oxidant with potassium permanganate as the main agent. They have been used to remove reducing substances such as iron and manganese from water. The permanganate composite chemical currently used by the applicant is formed by loading potassium permanganate with activated carbon. It can effectively remove reducing substances such as manganese ions from water, but it requires a long time. The untimely release of potassium permanganate limits the improvement of water treatment efficiency and also puts forward high requirements for the residence time of the treatment facility.

[0005] Furthermore, the conventional Fenton reaction method has significant drawbacks: even a slight overdose of the reagent can cause the treated wastewater to turn yellow again, and hydrogen peroxide, being a strong oxidant, places high demands on the corrosion resistance of the treatment facilities. Commercially available water treatment agents generally suffer from the following problems: raw materials are not environmentally friendly enough, the reagents have limited functionality, require large dosages, involve complex dosing procedures, place high demands on dosing equipment, have long reaction times, result in incomplete precipitation of reaction products, cause the treated water to easily turn discolored again, and are prone to secondary pollution.

[0006] Therefore, developing a water treatment compound that can shorten the pre-oxidation time and improve the treatment efficiency while ensuring the treatment effect is of great practical significance. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a permanganate composite agent and its application in water treatment, as detailed below: A permanganate composite agent includes particles A and particles B; the mass ratio of particles A to particles B is 1:0.2-0.5. Particle A contains the following components in the following mass ratio: 4-8 parts of potassium permanganate; 15-25 parts activated carbon; 1-2 parts of carbonate or bicarbonate; 30-40 parts of polyferric sulfate; 1-2 parts chitosan and sodium alginate; The potassium permanganate is supported on activated carbon and serves as a core component together with carbonates or bicarbonates. Alternatively, the carbonate or bicarbonate is co-supported with potassium permanganate on activated carbon as a component of the core. The mixture of polyferric sulfate, chitosan, and sodium alginate forms an outer shell that coats the surface of the core, forming particle A; Particle B contains the following components in the following mass ratio: 5-8 parts sodium percarbonate; Ascorbic acid 0.5-2 parts; 10-15 parts of porous carrier; 15-20 parts of polyferric sulfate; In this embodiment, sodium percarbonate and ascorbic acid are loaded onto the porous carrier as the core, and polyferric sulfate is used as the outer shell to coat the surface of the loaded porous carrier.

[0008] Furthermore, the porous carrier of the particle B is selected from one or more of diatomaceous earth, bentonite, and zeolite powder.

[0009] Furthermore, in the particle A, the mass ratio of polyferric sulfate to chitosan + sodium alginate is 10-5:1; the thickness of the outer shell is 300-500μm, and the porosity is 20%-35%; the mass ratio of chitosan to sodium alginate is 1:1-2. In particle B, the thickness of the outer shell of polyferric sulfate is 100-200 μm.

[0010] Furthermore, the carbonate is sodium carbonate or potassium carbonate, and the bicarbonate is sodium bicarbonate or potassium bicarbonate.

[0011] Moreover, the activated carbon is activated carbon that has undergone oxidation modification treatment. The oxidation modification treatment method is as follows: the activated carbon is soaked in a 10%-30% nitric acid solution at a solid-liquid ratio of 1:5-1:10, stirred and refluxed in a water bath at 60-90℃ for 2-4 hours, cooled and filtered, washed with deionized water until the pH is close to neutral, and dried at 105℃ to constant weight.

[0012] Furthermore, the core of particle A also includes a bubble nucleating agent, which is selected from nano-silica or nano-calcium carbonate, and its amount is 0.5%-1% of the total mass of particle A.

[0013] Furthermore, the preparation method of the particle A is as follows: (1) Dissolve potassium permanganate in water, add activated carbon, stir and adsorb for 2-4 hours, and dry to obtain potassium permanganate supported activated carbon; (2) Dissolve the carbonate or bicarbonate in water, add the potassium permanganate-supported activated carbon, stir for 2-4 hours, and dry to obtain co-supported activated carbon; (3) Mix polyferric sulfate with chitosan and sodium alginate, and coat the co-loaded activated carbon surface by tableting, centrifugal granulation or fluidized bed coating, and dry to obtain particles A.

[0014] After particle A is added to the water, the polyferric sulfate in the outer shell first hydrolyzes to produce H. + H + As chitosan passes through the outer shell, it undergoes protonation and swelling, increasing the shell's porosity and loosening its structure, thereby accelerating the H... + Inward diffusion; H + After diffusing to the core, it reacts with carbonates or bicarbonates to generate CO2 microbubbles in situ. The CO2 microbubbles create instantaneous pressure inside particle A. At the same time, chitosan, as a thickener and structural framework, can improve the stability of the bubble interface, prolong the residence time of microbubbles inside the particle, enhance the physical pumping effect, and promote the rapid release of potassium permanganate from the pores of activated carbon. Meanwhile, the micro-convection generated by the bursting of bubbles further enhances the diffusion and mixing of potassium permanganate.

[0015] Furthermore, the outer shell of particle A is composed of polyferric sulfate, chitosan, and sodium alginate. When the pH of the water is high (such as industrial wastewater), the outer shell swells or dissolves more rapidly. + The release rate increases, CO2 production accelerates, and potassium permanganate release speeds up to compensate for the decrease in potassium permanganate oxidation capacity under alkaline conditions; when the water body pH is neutral or weakly acidic (such as municipal sewage and surface sewage), the shell response is mild, and potassium permanganate is released at a normal rate.

[0016] Furthermore, the preparation method of the particle B is as follows: (1) Dry the diatomaceous earth at 80-105℃ for 2-4 hours until constant weight to obtain pretreated diatomaceous earth; (2) Dissolve ascorbic acid in deionized water to prepare a solution with a mass fraction of 10%-20%, add pretreated diatomaceous earth, stir and soak for 2-4 hours, filter, and vacuum dry the solid at 40-50℃ to obtain diatomaceous earth loaded with ascorbic acid. (3) Add the pretreated diatomaceous earth and sodium percarbonate into a closed mixer and perform high-shear mixing for 15-30 minutes under nitrogen protection. The shear line velocity is 5-10 m / s, so that the sodium percarbonate microcrystals are embedded in the porous structure of the diatomaceous earth surface to obtain diatomaceous earth loaded with sodium percarbonate. Through high-shear mixing, the sodium percarbonate microcrystals can be firmly attached to the pores of the carrier surface, avoiding them from falling off or prematurely contacting and failing with ascorbic acid during subsequent granulation and storage. (4) Mix diatomaceous earth loaded with ascorbic acid with sodium percarbonate to obtain a uniformly mixed core material after granulation. (5) Coat the core material with polyferric sulfate and control the outer shell thickness to 100-200 μm to obtain particle B.

[0017] After particle B is added to the water, the outer shell of the polyferric sulfate gradually hydrolyzes, and water from the water permeates into the inner core; after ascorbic acid dissolves, it reacts with H2 produced by the hydrolysis of polyferric sulfate. + Together, they form a localized acidic microenvironment, accelerating the decomposition of sodium percarbonate and releasing H2O2. H2O2 then reacts with Fe produced by the reduction of ascorbic acid. 2+ and trace metal ions (such as Mn) already present in the water body 2 + Under the catalysis of , highly active oxide species such as hydroxyl radicals (·OH) are generated, which form a synergistic effect with the oxidation of potassium permanganate released by the particles, further degrading difficult-to-treat organic matter; at the same time, the porous carrier has adsorption properties, which can enrich small molecule organic matter and heavy metal ions in the water, and increase the local reaction concentration; after the polyferric sulfate shell dissolves, it releases iron ions, which play a coagulation and precipitation role, and coagulate and precipitate the oxidation degradation products and suspended solids; through the combined effects of oxidation, adsorption and coagulation, the efficient removal of pollutants from wastewater is achieved.

[0018] On the other hand, the present invention provides the application of permanganate composite agent for water treatment, wherein granules A and B are added to the wastewater to be treated simultaneously; or granules A and B are added to the wastewater to be treated sequentially, with granules A added first and granules B added after an interval of 30-60 minutes.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. In this invention, after particle A is added to the water, the polyferric sulfate first hydrolyzes to produce H₂. + H + As the chitosan passes through its outer shell, the amino groups in the chitosan are protonated under acidic conditions, leading to shell swelling, increased porosity, and a looser structure, thereby accelerating the H2O process. + Inward diffusion; H +After diffusing to the core, it reacts with carbonates or bicarbonates to generate CO2 microbubbles in situ. These CO2 microbubbles create instantaneous pressure inside particle A. Simultaneously, chitosan, acting as a thickener and structural framework, improves the stability of the bubble interface, prolongs the residence time of the microbubbles inside the particle, and enhances the physical pumping effect, allowing potassium permanganate to be more fully squeezed out and released from the pores of activated carbon. Bubble rupture further enhances the diffusion and mixing of potassium permanganate, shortening the pre-oxidation time of traditional PPC to 10-15 minutes, significantly improving water treatment efficiency. Meanwhile, sodium percarbonate in particle B reacts with ascorbic acid to generate H2O2 and further produces ·OH, forming a synergistic oxidation system with potassium permanganate. This system then oxidizes stubborn organic compounds (such as phenols, anilines, and dye intermediates) that are difficult for potassium permanganate to degrade, avoiding ineffective consumption of the oxidant and further improving overall oxidation efficiency.

[0020] 2. The composite agent provided by this invention is applicable to wastewater treatment of different water qualities. The outer shell of particle A is composed of polyferric sulfate, chitosan, and sodium alginate. When the pH of the water is high (such as industrial wastewater), the outer shell swells or dissolves more quickly. + The release rate increases, CO2 production accelerates, and potassium permanganate release speeds up to compensate for the decrease in potassium permanganate oxidation capacity under alkaline conditions; when the water body pH is neutral or weakly acidic (such as municipal sewage and surface sewage), the shell response is mild, and potassium permanganate is released at a normal rate.

[0021] 3. In this invention, the outer shell of polyferric sulfate in particle B releases iron ions to play a coagulation and precipitation role, while the core, through the combination of sodium percarbonate and ascorbic acid, forms a localized acidic microenvironment after water penetration, activating sodium percarbonate to release H2O2, thereby generating highly active oxide species such as hydroxyl radicals (·OH), which form an oxidative synergistic effect with potassium permanganate released by particle A, effectively degrading difficult-to-treat organic matter; moreover, the Fe produced by the reduction of ascorbic acid in particle B... 2+ It also has a certain reducing property and can react with potassium permanganate to produce MnO2, etc. It has catalytic oxidation and adsorption effects, and can help particle A improve oxidation efficiency.

[0022] 4. This invention does not rely on the Fenton reaction system, so there is no problem of wastewater turning yellow after treatment due to excessive hydrogen peroxide, and there is no need to take special anti-corrosion measures for the treatment facilities against strong oxidizing hydrogen peroxide, which reduces equipment investment and operation and maintenance costs. Attached Figure Description

[0023] Figure 1 A comparison chart of the pre-oxidation completion times for each group in wastewater A; Figure 2 A comparison chart of the pre-oxidation completion times for each group in wastewater B; Figure 3 This is a comparison chart showing the treatment effects for some groups. Detailed Implementation

[0024] Example 1 A permanganate composite agent includes particles A and particles B; the mass ratio of particles A to particles B is 1:0.2. Particle A contains the following components in the following mass ratio: 6 parts potassium permanganate; 15 parts activated carbon; 1.5 parts carbonate; 35 parts of polyferric sulfate; 1.5 parts chitosan and sodium alginate; The potassium permanganate is supported on activated carbon and serves as a core component together with carbonate. The mixture of polyferric sulfate, chitosan, and sodium alginate forms an outer shell that coats the surface of the core, forming particle A; Particle B contains the following components in the following mass ratio: 7 parts sodium percarbonate; 1 part ascorbic acid; 13 portions of porous carrier; 18 parts of polyferric sulfate; In this embodiment, sodium percarbonate and ascorbic acid are loaded onto the porous carrier as the core, and polyferric sulfate is used as the outer shell to coat the surface of the loaded porous carrier.

[0025] Preferably, the porous carrier of particle B is bentonite.

[0026] Preferably, in particle A, the mass ratio of polyferric sulfate to chitosan + sodium alginate is 10-5:1; the thickness of the outer shell is 400 μm and the porosity is 30%; the mass ratio of chitosan to sodium alginate is 1:1. In particle B, the thickness of the outer shell of polyferric sulfate is 150 μm.

[0027] Preferably, the carbonate is potassium carbonate.

[0028] Preferably, the activated carbon is activated carbon that has undergone oxidative modification. The oxidative modification method is as follows: the activated carbon is soaked in a 20% nitric acid solution at a solid-liquid ratio of 1:8, stirred and refluxed in a 75°C water bath for 3 hours, cooled and filtered, washed with deionized water until the pH is close to neutral, and dried at 105°C to constant weight.

[0029] Preferably, the core of particle A further includes a bubble nucleating agent, which is nano-calcium carbonate, and its amount is 0.8% of the total mass of particle A.

[0030] Preferably, the preparation method of particle A is as follows: (1) Dissolve potassium permanganate in water, add activated carbon, stir and adsorb for 3 hours, and dry to obtain potassium permanganate supported activated carbon; (2) Dissolve the carbonate or bicarbonate in water, add the potassium permanganate-supported activated carbon, stir for 3 hours, and dry to obtain co-supported activated carbon; (3) Mix polyferric sulfate with chitosan and sodium alginate, and coat the co-loaded activated carbon surface by tableting, centrifugal granulation or fluidized bed coating, and dry to obtain particles A.

[0031] Preferably, the preparation method of particle B is as follows: (1) The bentonite was dried at 95°C for 3 hours to constant weight to obtain pretreated bentonite; (2) Dissolve ascorbic acid in deionized water to prepare a 15% solution by mass, add pretreated bentonite, stir and soak for 3 hours, filter, and vacuum dry the solid at 45°C to obtain bentonite loaded with ascorbic acid. (3) Add the pretreated bentonite and solid sodium percarbonate into a closed mixer and mix for 20 minutes under nitrogen protection to obtain bentonite loaded with sodium percarbonate. (4) Bentonite loaded with ascorbic acid and bentonite with sodium percarbonate are mixed to obtain a uniformly mixed core material after granulation. (5) Coating the core material with polyferric sulfate and controlling the outer shell thickness to 150 μm to obtain particle B.

[0032] Example 2 A permanganate composite agent includes particles A and particles B; the mass ratio of particles A to particles B is 1:0.5. Particle A contains the following components in the following mass ratio: 4 parts potassium permanganate; 15 parts activated carbon; 1 part of bicarbonate; 30 parts of polyferric sulfate; One part chitosan and sodium alginate; The potassium permanganate is supported on activated carbon and together with bicarbonate serves as the core component. The mixture of polyferric sulfate, chitosan, and sodium alginate forms an outer shell that coats the surface of the core, forming particle A; Particle B contains the following components in the following mass ratio: 5 parts sodium percarbonate; 0.5 parts ascorbic acid; 10 portions of porous carrier; 15 parts of polyferric sulfate; In this embodiment, sodium percarbonate and ascorbic acid are loaded onto the porous carrier as the core, and polyferric sulfate is used as the outer shell to coat the surface of the loaded porous carrier.

[0033] Preferably, the porous carrier of particle B is diatomaceous earth.

[0034] Preferably, in particle A, the mass ratio of polyferric sulfate to chitosan + sodium alginate is 10:1; the thickness of the outer shell is 300 μm and the porosity is 20%; the mass ratio of chitosan to sodium alginate is 1:2. In particle B, the thickness of the outer shell of polyferric sulfate is 100 μm.

[0035] Preferably, the bicarbonate is sodium bicarbonate or potassium bicarbonate.

[0036] Preferably, the activated carbon is activated carbon that has undergone oxidative modification. The oxidative modification method is as follows: the activated carbon is soaked in a 10% nitric acid solution at a solid-liquid ratio of 1:5, stirred and refluxed in a 60°C water bath for 2 hours, cooled and filtered, washed with deionized water until the pH is close to neutral, and dried at 105°C to constant weight.

[0037] Preferably, the core of particle A further includes a bubble nucleating agent, which is nano-silica, and its amount is 0.5% of the total mass of particle A.

[0038] Preferably, the preparation method of particle A is as follows: (1) Dissolve potassium permanganate in water, add activated carbon, stir and adsorb for 2 hours, and dry to obtain potassium permanganate supported activated carbon; (2) Dissolve the carbonate or bicarbonate in water, add the potassium permanganate-supported activated carbon, stir for 2 hours, and dry to obtain co-supported activated carbon; (3) Mix polyferric sulfate with chitosan and sodium alginate, and coat the co-loaded activated carbon surface by tableting, centrifugal granulation or fluidized bed coating, and dry to obtain particles A.

[0039] Preferably, the preparation method of particle B is as follows: (1) The diatomaceous earth was dried at 80°C for 2 hours until constant weight to obtain pretreated diatomaceous earth; (2) Dissolve ascorbic acid in deionized water to prepare a 10% solution by mass, add pretreated diatomaceous earth, stir and soak for 2 hours, filter, and vacuum dry the solid at 40°C to obtain diatomaceous earth loaded with ascorbic acid; (3) Add the pretreated diatomaceous earth and solid sodium percarbonate into a closed mixer and mix for 15 minutes under nitrogen protection to obtain diatomaceous earth loaded with sodium percarbonate. (4) Mix diatomaceous earth loaded with ascorbic acid with sodium percarbonate to obtain a uniformly mixed core material after granulation. (5) Coating the core material with polyferric sulfate and controlling the outer shell thickness to 100 μm to obtain particle B.

[0040] Example 3 A permanganate composite agent includes particles A and particles B; the mass ratio of particles A to particles B is 1:0.3. Particle A contains the following components in the following mass ratio: 8 parts potassium permanganate; 25 parts activated carbon; 2 parts carbonate; 40 parts of polyferric sulfate; Two parts chitosan and sodium alginate; The carbonate and potassium permanganate are jointly supported on activated carbon as the core component; The mixture of polyferric sulfate, chitosan, and sodium alginate forms an outer shell that coats the surface of the core, forming particle A; Particle B contains the following components in the following mass ratio: Sodium percarbonate 6 parts; 1 part ascorbic acid; 12 portions of porous carrier; 18 parts of polyferric sulfate; In this embodiment, sodium percarbonate and ascorbic acid are loaded onto the porous carrier as the core, and polyferric sulfate is used as the outer shell to coat the surface of the loaded porous carrier.

[0041] Preferably, the porous carrier of particle B is zeolite powder.

[0042] Preferably, in particle A, the mass ratio of polyferric sulfate to chitosan + sodium alginate is 8:1; the thickness of the outer shell is 400 μm and the porosity is 30%; the mass ratio of chitosan to sodium alginate is 1:1.5. In particle B, the thickness of the outer shell of polyferric sulfate is 150 μm.

[0043] Preferably, the carbonate is potassium carbonate.

[0044] Preferably, the activated carbon is activated carbon that has undergone oxidative modification treatment. The oxidative modification treatment method is as follows: the activated carbon is soaked in a 30% nitric acid solution at a solid-liquid ratio of 1:10, stirred and refluxed in a 90°C water bath for 4 hours, cooled and filtered, washed with deionized water until the pH is close to neutral, and dried at 105°C to constant weight.

[0045] Preferably, the core of particle A further includes a bubble nucleating agent, which is nano-silica, and its amount is 0.8% of the total mass of particle A.

[0046] Preferably, the preparation method of particle A is as follows: (1) Dissolve potassium permanganate in water, add activated carbon, stir and adsorb for 4 hours, and dry to obtain potassium permanganate supported activated carbon; (2) Dissolve the carbonate or bicarbonate in water, add the potassium permanganate-supported activated carbon, stir for 4 hours, and dry to obtain co-supported activated carbon; (3) Mix polyferric sulfate with chitosan and sodium alginate, and coat the co-loaded activated carbon surface by tableting, centrifugal granulation or fluidized bed coating, and dry to obtain particles A.

[0047] Preferably, the preparation method of particle B is as follows: (1) The diatomaceous earth was dried at 105°C for 4 hours until constant weight to obtain pretreated diatomaceous earth; (2) Dissolve ascorbic acid in deionized water to prepare a solution with a mass fraction of 20%, add pretreated diatomaceous earth, stir and soak for 4 hours, filter, and vacuum dry the solid at 50°C to obtain diatomaceous earth loaded with ascorbic acid; (3) Add the pretreated diatomaceous earth and solid sodium percarbonate into a sealed mixer and mix for 30 minutes under nitrogen protection to obtain diatomaceous earth loaded with sodium percarbonate. (4) Mix diatomaceous earth loaded with ascorbic acid with sodium percarbonate to obtain a uniformly mixed core material after granulation. (5) Coating the core material with polyferric sulfate and controlling the outer shell thickness to 200 μm to obtain particle B.

[0048] Comparative Example 1 The difference between this comparative example and Example 1 is that no carbonate was added to the core of particle A.

[0049] Comparative Example 2 The difference between this comparative example and Example 1 is that no chitosan and sodium alginate were added to the outer shell of particle A.

[0050] Comparative Example 3 The difference between this comparative example and Example 1 is that the composite agent contains only particle A (excluding particle B).

[0051] Comparative Example 4 The difference between this comparative example and Example 1 is that no ascorbic acid is added to particle B.

[0052] Comparative Example 5 Granule A does not contain carbonates, but CO2 microbubbles are introduced into the water simultaneously during addition (the bubble size and flow rate are comparable to the in-situ gas production estimated in Example 1).

[0053] Comparative Example 6 The difference between this comparative example and Example 1 is that ascorbic acid in particle B is replaced with an equimolar amount of citric acid.

[0054] Experimental Section Wastewater A: Taken from the secondary sedimentation tank effluent of a municipal wastewater treatment plant. Water quality characteristics: pH 7.0-7.5, COD 80-120 mg / L, color 15-20 times, total phosphorus 0.5-1.0 mg / L, containing a small amount of recalcitrant organic matter.

[0055] Wastewater B: Taken from the effluent of a dyeing and printing factory's biochemical treatment plant. The water quality characteristics are: pH 8.5-9.5, COD 150-200 mg / L, color 50-80 times, total phosphorus 1.5-2.5 mg / L, and the water contains stubborn organic matter such as aniline and dye intermediates.

[0056] Experimental groups: one group each of Comparative Examples 1-6 and Examples 1-3.

[0057] Experiment 1: Determination of the Dosage of the Compound Agent To determine a reasonable dosage of the compound agent, the compound agent from Example 1 was used as the test agent. 1 L each of wastewater A (COD≈100 mg / L) and wastewater B (COD≈180 mg / L) were taken, and the compound agent dosage was set at 10, 15, 20, 25, 30, and 40 mg / L, respectively. The mass ratio of granules A to granules B was 1:0.2. The compound agent was added simultaneously, and the mixture was first rapidly stirred at 200 rpm for 30 seconds to ensure uniform dispersion. Then, the mixture was slowly stirred at 60 rpm for a total reaction time of 60 minutes.

[0058] After the reaction was completed, water samples were filtered through a 0.45 μm filter membrane, and the COD value was determined using the dichromate method. The COD removal rate was calculated. Three parallel samples were set for each group, and the average value of the results was taken. See Tables 1 and 2.

[0059] Table 1. COD removal rate of wastewater A as a function of dosage concentration

[0060] When the dosage concentration increased from 10 mg / L to 25 mg / L, the COD removal rate increased significantly from 52.3% to 88.5%. However, when the dosage concentration exceeded 25 mg / L, the increase in COD removal rate slowed down significantly.

[0061] Table 2. COD removal rate of wastewater B as a function of dosage concentration

[0062] When the dosage concentration increased from 10 mg / L to 30 mg / L, the COD removal rate significantly increased from 41.5% to 85.2%. However, when the dosage concentration exceeded 30 mg / L, the increase in COD removal rate slowed down significantly.

[0063] The final determination was that the dosage for wastewater A was 25 mg / L, and the dosage for wastewater B was 30 mg / L.

[0064] Experiment 2 Comparison of Pre-oxidation Time I. Comparison of Pre-oxidation Time for Wastewater A Take nine 200mL beakers and add 120mL of wastewater A to each. Add the composite agent of Comparative Examples 1-6 and Examples 1-3 (with particles A and B added simultaneously) at a concentration of 25 mg / L. Place the beakers on a six-piece stirrer and disperse at 200rpm for 30 seconds, followed by stirring at 60rpm for 10 seconds. Take 10mL samples at 2min, 5min, 10min, 15min, 20min, 25min, 30min, 40min, 50min, 60min, 70min, and 80min, and immediately filter through a 0.45μm filter membrane to terminate the reaction.

[0065] COD removal rate was determined using the dichromate method. The shortest time corresponding to when the COD removal rate (at 60 min) reached 90% of the final equilibrium removal rate was defined as the pre-oxidation completion time for that group. The test results are shown in Table 3 and [Table data would be inserted here]. Figure 1 .

[0066] Table 3 Comparison of pre-oxidation completion time for different groups of wastewater A

[0067] As can be seen from Table 3, the pre-oxidation completion time of Examples 1-3 is 10-15 minutes, which is significantly better than that of Comparative Examples 1 and 2, proving that the CO2 microbubbles generated by the carbonate in particle A and the chitosan / sodium alginate are both indispensable. Comparative Example 3 is slower than the Example group, indicating that the addition of particle B has a synergistic accelerating effect and can further shorten the pre-oxidation time. Comparative Example 4 is slightly slower than Example 1, and its core role is reflected in the deep oxidation stage.

[0068] Comparative Example 5, which contained no carbonates but was aerated with CO2 externally, failed to create an instantaneous pressure pumping effect within the particles. The efficiency of potassium permanganate being extruded from the activated carbon pores was far lower than that of in-situ gas production, resulting in a significantly longer pre-oxidation time compared to the Example group. Comparative Example 6 replaced ascorbic acid with citric acid. Citric acid could still activate sodium percarbonate to release H2O2, and the pre-oxidation stage was similar to that of the Example group and Comparative Example 4. However, citric acid lacked the reducing properties of ascorbic acid and its synergistic redox ability with iron ions, a difference that manifested in the subsequent deep oxidation stage.

[0069] II. Comparison of Pre-oxidation Time for Wastewater B Take nine 200mL beakers and add 120mL of wastewater B to each. Add the composite agents from Comparative Examples 1-6 and Examples 1-3 at a dosage of 30mg / L, respectively. Place the beakers on a six-unit stirrer and stir rapidly at 200rpm for 30 seconds, followed by slow stirring at 60rpm. Take 10mL samples at 2, 5, 10, 15, 20, 25, 30, 40, 50, 60, 70, and 80 minutes, and immediately filter through a 0.45μm filter membrane to terminate the reaction.

[0070] COD was determined using the dichromate method. The shortest time corresponding to the COD removal rate reaching 90% of the final equilibrium removal rate (at 60 min) was defined as the pre-oxidation completion time for this group. The results are shown in Table 4 and... Figure 2 .

[0071] Table 4 Comparison of pre-oxidation completion time for each group of wastewater B

[0072] The pre-oxidation completion time trend of each group was consistent with that of wastewater A, but slightly longer overall. This is likely because wastewater B had a higher initial COD concentration and contained persistent organic matter such as aniline and dye intermediates, requiring a longer oxidation reaction time. The pre-oxidation completion time of Examples 1-3 was 15-20 minutes, still significantly better than the comparative examples, verifying the broad adaptability of the composite agent of this invention to different water qualities.

[0073] Experiment 3 Comparison of pollutant removal effects under different water quality conditions Take 120 mL each of wastewater A and wastewater B, and place them in separate 200 mL beakers. Add the composite agent from Comparative Examples 1-6 and Examples 1-3 at the following concentrations: 25 mg / L for wastewater A and 30 mg / L for wastewater B. The addition method is as follows: add granules A first, then add granules B after a 30-minute interval. After a total reaction time of 60 minutes, take samples for testing. COD: dichromate method; color: dilution factor method; total phosphorus: ammonium molybdate spectrophotometric method. The results are shown in Table 5.

[0074] Table 5 Comparison of pollutant removal efficiency under different water quality conditions

[0075] Table 5 shows that the COD removal rate of Example 1 in alkaline wastewater B is not significantly different from that in neutral wastewater; however, the COD removal rate of Comparative Example 1 in wastewater B is 60.3%, and the color removal rate is 65.2%; while that of Comparative Example 2 is 68.7% and 72.1%, respectively, showing a significant decrease. This verifies the mechanism by which the shell of particle A accelerates the release of potassium permanganate under alkaline conditions to compensate for the weakened oxidizing capacity. In addition, the removal rates of Comparative Examples 3 and 4 are also relatively low, which can be attributed to the lack of synergistic oxidizing effect of particle B.

[0076] Example 1 showed a significantly higher COD removal rate for wastewater B containing persistent organic matter compared to Comparative Examples 3 and 4, demonstrating that the hydroxyl radicals generated by sodium percarbonate and ascorbic acid in particles B form a synergistic oxidation system with potassium permanganate. Furthermore, the removal rates of Comparative Examples 1 and 2 were lower than those of Comparative Examples 3 and 4, highlighting the importance of the sufficient release of potassium permanganate by carbonates and chitosan / sodium alginate.

[0077] The total phosphorus removal rate of Example 1 was significantly better than that of Comparative Example 3, proving that the polyferric sulfate shell in particle B has a significant effect on phosphorus removal. Meanwhile, the total phosphorus removal rates of Comparative Examples 1, 2, and 4 were all lower than those of Example 1, indicating that the CO2 microbubbles generated by carbonate, the pH swelling of chitosan / sodium alginate, and the synergistic oxidation of ·OH activated by ascorbic acid all indirectly enhanced the phosphorus removal effect by improving the overall oxidation and coagulation efficiency, reflecting the synergistic effect between the components of this invention.

[0078] Comparative Example 5 showed poor results because external aeration could not replace the CO2 microbubbles generated in situ by the core of Particle A. The external bubbles could not enter the micropores of activated carbon and only diffused in the water. They could not form a physical pumping effect of instantaneous pressure inside the pores of activated carbon, so potassium permanganate could not be fully and quickly squeezed out and released. At the same time, external aeration may have aggravated the ineffective decomposition of potassium permanganate in non-target areas, which would reduce its effective contact efficiency with the target pollutants.

[0079] Comparative Example 6 showed significantly lower performance than the Example. Notably, the pre-oxidation time of Comparative Example 6 was similar to that of the Example, indicating that citric acid can effectively activate sodium percarbonate to release H2O2, performing reasonably well in the pre-oxidation stage. However, its COD removal capacity in the deep oxidation stage was significantly insufficient. Ascorbic acid not only provides an acidic microenvironment to activate sodium percarbonate, but more importantly, its reducing properties can reduce iron in the system, thereby driving a Fenton-like reaction to continuously generate highly reactive hydroxyl radicals. While citric acid can provide an acidic environment, it lacks this redox cycle capability, resulting in a significant decrease in ·OH yield and making it difficult to achieve deep mineralization of stubborn organic matter. Furthermore, the Fe produced by the reduction of ascorbic acid... 2+ It can also react with potassium permanganate to generate MnO2, which has catalytic adsorption activity, further assisting the oxidation process.

[0080] Take photos of the treated water samples and record the results. (See attached image) Figure 3 As can be clearly seen from the figure, the effect of the embodiment is significantly better than that of the control model.

[0081] Experiment 4: Effect of the dosing sequence of particles A and B on COD removal efficiency Take three 2L beakers, add 120mL of wastewater B to each, and perform the following treatment: Group 1: Particle A and Particle B are added simultaneously; Group 2: Add granules A first, and then add granules B after a 30-minute interval; Group 3: Add granule B first, and then add granule A after a 30-minute interval; The mass ratio of granule A to granule B is 1:0.35, and the total dosage is 30 mg / L.

[0082] All three groups were run on a six-unit stirrer. At a total reaction time of 60 minutes, samples were taken from each group, filtered through a 0.45 μm filter membrane, and the COD value was determined by the dichromate method. The COD removal rate was calculated. Three parallel samples were made for each group. The results were taken as the mean ± standard deviation. The results are shown in Table 6.

[0083] Table 6 Comparison of COD removal rates under different dosing sequences

[0084] Table 6 shows that the order of addition of particles A and B has a significant impact on the synergistic oxidation effect of the composite agent. Group 2, which added particles A first for pre-oxidation and then added particles B for deep mineralization after a 30-minute interval, had a higher COD removal rate. Group 1 was second best, and Group 3 had the worst effect. This proves that the separation and connection of the pre-oxidation and deep oxidation in the present invention is the key to improving the oxidation effect and avoiding the ineffective consumption of oxidant.

Claims

1. A permanganate composite agent, comprising particles A and particles B; wherein the mass ratio of particles A to particles B is 1:0.2-0.5; characterized in that, Particle A contains the following components in the following mass ratio: 4-8 parts of potassium permanganate; 15-25 parts activated carbon; 1-2 parts of carbonate or bicarbonate; 30-40 parts of polyferric sulfate; 1-2 parts chitosan and sodium alginate; The potassium permanganate is supported on activated carbon and serves as a core component together with carbonates or bicarbonates. Alternatively, the carbonate or bicarbonate is co-supported with potassium permanganate on activated carbon as a component of the core. The mixture of polyferric sulfate, chitosan, and sodium alginate forms an outer shell that coats the surface of the core, forming particle A; Particle B contains the following components in the following mass ratio: 5-8 parts sodium percarbonate; Ascorbic acid 0.5-2 parts; 10-15 parts of porous carrier; 15-20 parts of polyferric sulfate; In this embodiment, sodium percarbonate and ascorbic acid are loaded onto the porous carrier as the core, and polyferric sulfate is used as the outer shell to coat the surface of the loaded porous carrier.

2. The permanganate composite agent according to claim 1, characterized in that, The porous carrier of particle B is selected from one or more of diatomaceous earth, bentonite, and zeolite powder.

3. The permanganate composite agent according to claim 1, characterized in that, In particle A, the total mass ratio of polyferric sulfate:chitosan + sodium alginate is 10-5:1, the thickness of the outer shell is 300-500μm, and the porosity is 20%-35%; the mass ratio of chitosan to sodium alginate is 1:1-2. The thickness of the outer shell of particle B is 100-200 μm.

4. The permanganate composite agent according to claim 1, characterized in that, The carbonate is sodium carbonate or potassium carbonate, and the bicarbonate is sodium bicarbonate or potassium bicarbonate.

5. The permanganate composite agent according to claim 1, characterized in that, The activated carbon is activated carbon that has undergone oxidation modification. The oxidation modification method is as follows: the activated carbon is soaked in a 10%-30% nitric acid solution at a solid-liquid ratio of 1:5-10, stirred and refluxed in a water bath at 60-90℃ for 2-4 hours, cooled and filtered, washed with deionized water until the pH is close to neutral, and dried at 105℃ to constant weight.

6. The permanganate composite agent according to claim 1, characterized in that, The core of particle A also includes a bubble nucleating agent, which is selected from either nano-silica or nano-calcium carbonate, and the amount used is 0.5%-1% of the total mass of particle A.

7. A permanganate composite agent according to claim 6, characterized in that, The preparation method of particle A is as follows: (1) Dissolve potassium permanganate in water, add activated carbon, stir and adsorb for 2-4 hours, and dry to obtain potassium permanganate supported activated carbon; (2) Dissolve the carbonate or bicarbonate in water, add the potassium permanganate-supported activated carbon, stir for 2-4 hours, and dry to obtain co-supported activated carbon; (3) Mix polyferric sulfate with chitosan and sodium alginate, and coat the co-loaded activated carbon surface by tableting, centrifugal granulation or fluidized bed coating, and dry to obtain particles A.

8. The permanganate composite agent according to any one of claims 1-6, characterized in that, The preparation method of particle B is as follows: (1) Dry the diatomaceous earth at 80-105℃ for 2-4 hours until constant weight to obtain pretreated diatomaceous earth; (2) Dissolve ascorbic acid in deionized water to prepare a solution with a mass fraction of 10%-20%, add pretreated diatomaceous earth, stir and soak for 2-4 hours, filter, and vacuum dry the solid at 40-50℃ to obtain diatomaceous earth loaded with ascorbic acid. (3) Add the pretreated diatomaceous earth and solid sodium percarbonate into a closed mixer and mix for 15-30 minutes under nitrogen protection to obtain diatomaceous earth loaded with sodium percarbonate. (4) Mix diatomaceous earth loaded with ascorbic acid with sodium percarbonate to obtain a uniformly mixed core material after granulation. (5) Coat the core material with polyferric sulfate and control the outer shell thickness to 100-200 μm to obtain particle B.

9. The application of the permanganate composite agent according to any one of claims 1-8, characterized in that, For water treatment, granules A and B are added simultaneously to the wastewater to be treated.

10. The application of the permanganate composite agent according to any one of claims 1-8, characterized in that, For water treatment, granules A and B are added to the wastewater to be treated sequentially, with granules A added first and granules B added after an interval of 30-60 minutes.

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