A method for activating PAA by complex modified birnessite to degrade organic pollutants

Abstract

The present invention discloses a method for activating PAA by complex-modified birnessite to degrade organic pollutants, which relates to the technical field of sewage treatment. First, prepare an aqueous solution of potassium permanganate and hydrochloric acid for standby; then, during the stirring and heating of the potassium permanganate solution, dropwise add the hydrochloric acid solution through a constant flow pump and continuously react to generate a suspension; then, keep the suspension at a constant temperature and stand still, followed by suction filtration, and then successively carry out water washing, alcohol washing, drying, grinding and sieving treatments to obtain birnessite powder; finally, mix it with a complexing agent solution, and obtain a complex-modified birnessite catalyst after surface complexation reaction modification. The method for activating PAA by complex-modified birnessite to degrade organic pollutants optimizes the distribution of manganese active sites on the surface of birnessite and the charge transfer path through the complexing agent. Under the condition of normal temperature without external energy input, it realizes the efficient activation of PAA, generates strongly oxidizing active free radicals, further oxidizes the organic pollutants in water, and degrades the organic pollutants.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and particularly relates to a method for activating PAA by complex modified birnessite to degrade organic pollutants. Background Art

[0002] Environmental endocrine disruptors, namely environmental hormones, are widely distributed in the natural environment and can invade the human body or biological systems through various channels. Their toxicity can disrupt the endocrine balance and cause abnormalities in the reproductive system. Sulfonamides, especially sulfamethoxazole (SMX), are typical environmental endocrine disruptors, which are stable in the environment, with almost no volatilization and hydrolysis. The removal ability of traditional water treatment technologies for SMX is limited. In contrast, although adsorption and membrane methods can effectively remove SMX, their high costs limit their large-scale application. In addition, the biological treatment of SMX takes a long time, and toxic by-products may be generated during the treatment process. These by-products are difficult to biodegrade and can cause long-term harm to the aquatic environment.

[0003] Advanced oxidation technologies based on the generation of reactive oxygen species (ROS) have received extensive attention due to their strong oxidation ability. Among many oxidants, peracetic acid (PAA) stands out for its environmental friendliness. After activation, PAA can generate highly reactive free radicals such as acetylperoxy radicals (CH3C(O)OO•) and hydroxyl radicals (•OH). These free radicals have extremely strong oxidation ability and can efficiently degrade organic pollutants in water, including some stubborn pollutants that are difficult to be treated by traditional methods. However, most of the existing PAA activation technologies rely on transition metal ions (such as 、 ) or ultraviolet light. Although the transition metal ion activation method is effective, there is a problem of catalyst loss, which not only increases the treatment cost but also may cause secondary pollution to the water body. At the same time, the use of transition metal ions may also generate metal sludge, requiring additional treatment steps. The ultraviolet light activation method faces the challenge of high energy consumption. Long-term high-intensity ultraviolet light irradiation not only increases the operating cost but also may damage the equipment. In addition, the heterogeneous catalytic system has relatively weak electron transfer ability, resulting in insufficient PAA activation ability and low ROS yield, making it difficult to meet the demand for efficient degradation of organic pollutants.

[0004] Birnessite is a strong oxidant that is widely present in the natural environment and easily undergoes oxidation-reduction reactions under natural conditions. Therefore, it can adsorb and exchange various cations and participate in the oxidation degradation process of organic pollutants. However, the synthesis of traditional birnessite usually requires high-temperature calcination or water bath heating, and the reaction conditions are usually complex and the preparation cost is high. Moreover, when traditional birnessite activates PAA to degrade organic pollutants, there will be dissolution phenomenon, resulting in secondary pollution, reduced catalyst activity, and poor reaction stability.

[0005] In addition, studies have shown that complexing agents can change the oxidation state distribution of Mn and promote the decomposition of PAA to generate free radicals. However, the complex-modified birnessite prepared by the coprecipitation method requires precise control of reaction conditions, is not suitable for large-scale preparation, and cannot timely change the type of complexing agent according to the conditions of polluted water bodies, resulting in poor flexibility.

[0006] In view of this, the present invention provides a method for activating PAA by complex-modified birnessite to degrade organic pollutants, which optimizes the distribution of manganese active sites on the surface of birnessite and the electron transfer path, and realizes the efficient activation of PAA and the rapid degradation of pollutants under normal temperature conditions without external energy input such as microwave, light, and electricity. Summary of the Invention

[0007] The object of the present invention is to provide a method for activating PAA by complex-modified birnessite to degrade organic pollutants, so as to solve the deficiencies in the prior art such as poor stability, poor PAA activation effect, and easy secondary pollution of water bodies when birnessite degrades organic pollutants.

[0008] To achieve the above object, the present invention provides the following technical solution: A preparation method of a complex-modified birnessite catalyst, specifically including the following steps:

[0009] S1. Prepare an aqueous potassium permanganate solution with a concentration of and an aqueous hydrochloric acid solution with a concentration of , and set aside;

[0010] S2. Add the prepared aqueous potassium permanganate solution in S1 to a beaker, stir and heat it, and then use a constant flow pump to dropwise add the prepared aqueous hydrochloric acid solution in S1 into the heated potassium permanganate solution. After the dropping is completed, react for 30 - 60 min to obtain a suspension;

[0011] S3. Let the suspension obtained in S2 stand in a constant temperature oven, then perform suction filtration and wash it with deionized water until the conductivity of the filtrate is less than , obtain a precipitate, and then successively perform alcohol washing, drying, grinding, and sieving on the obtained precipitate, and finally obtain birnessite powder;

[0012] S4. Add the birnessite powder obtained in S3 into a conical flask, and then add a complexing agent solution for mixing to modify the surface of birnessite through a complexation reaction to obtain a complex-modified birnessite catalyst.

[0013] Further, the heating temperature in S2 is 80 - 100 °C.

[0014] Further, in S3, the suspension is left standing in a constant-temperature oven, and the temperature of the oven is set to 50 - 80°C; the standing time is set to 10 - 18 h.

[0015] Further, in S4, the complexing agent is ethylenediaminetetraacetic acid or diethylenetriaminepentaacetic acid; the molar ratio of the birnessite powder to the complexing agent is 1 - 6:1.

[0016] The present invention also discloses a complex-modified birnessite catalyst, which is prepared by a preparation method of a complex-modified birnessite catalyst.

[0017] The present invention also discloses a method for activating PAA by a complex-modified birnessite to degrade organic pollutants, which specifically includes the following steps:

[0018] A1. Adding the complex-modified birnessite catalyst and peracetic acid to the polluted water body containing organic pollutants to obtain a mixed water body;

[0019] A2. Adjusting the pH of the mixed water body with an acid or a base, and carrying out a degradation reaction under normal temperature and pressure to obtain a degraded reaction solution.

[0020] Further, the concentration of the complex-modified birnessite catalyst in the A1 mixed water body is 0.025 g / L - 0.1 g / L; the organic pollutant is a sulfonamide drug.

[0021] Further, the concentration of peracetic acid in the A1 mixed water body is 0.5 mM - 5 mM.

[0022] Further, the A2 degradation reaction is carried out under the condition of pH 3 - 9.

[0023] Compared with the prior art, the method for activating PAA by a complex-modified birnessite to degrade organic pollutants provided by the present invention has the following beneficial effects:

[0024] 1. The complex-modified birnessite catalyst provided by the present invention has a simple preparation method, does not require high-temperature calcination, has a short catalytic time, and has a high degradation effect on organic pollutants; the degradation rate of sulfamethoxazole can reach more than 94% within 2 h, and has great application prospects in degrading organic pollutants in water bodies.

[0025] 2. The complex-modified birnessite catalyst provided by the present invention optimizes the distribution of manganese active sites on the surface of birnessite and the charge transfer path through the complexing action of EDTA, and can realize the efficient activation of PAA under normal temperature conditions without external energy input, generate strongly oxidizing active free radicals, further oxidize organic pollutants in water, degrade organic pollutants, and improve the water quality environment.

[0026] 3. The complex-modified birnessite catalyst provided by the present invention is easy to recycle and reuse, and can be reused multiple times. It is an environmentally friendly material without secondary pollution and is applicable to fields such as sewage treatment and environmental remediation. Description of the Drawings

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings.

[0028] Figure 1 Scanning electron microscope image (SEM) of the birnessite powder catalyst provided by the embodiment of the present invention;

[0029] Figure 2 X-ray diffraction pattern (XRD) of the birnessite powder catalyst provided by the embodiment of the present invention before and after the reaction. Detailed Embodiments

[0030] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the following will further introduce the present invention in detail with reference to the drawings.

[0031] A preparation method of a complex-modified birnessite catalyst specifically includes the following steps:

[0032] S1. Prepare an aqueous potassium permanganate solution with a concentration of and an aqueous hydrochloric acid solution with a concentration of for later use;

[0033] Specifically, prepare 300 mL of an aqueous potassium permanganate solution with a concentration of and 45 mL of an aqueous hydrochloric acid solution with a concentration of for later use.

[0034] S2. Add the aqueous potassium permanganate solution prepared in S1 to a beaker, stir and heat it, and then use a constant flow pump to gradually add the aqueous hydrochloric acid solution prepared in S1 drop by drop to the heated potassium permanganate solution. After the addition is complete, react for 30 - 60 minutes to obtain a suspension;

[0035] Specifically, add the aqueous potassium permanganate solution prepared in S1 to a beaker, stir and heat it to 100 °C, and then use a constant flow pump to gradually add the aqueous hydrochloric acid solution prepared in S1 drop by drop to the heated potassium permanganate solution at a rate of . After the addition is complete, react for 30 minutes to obtain a suspension.

[0036] S3. Leave the suspension obtained in S2 still in a constant-temperature oven, then perform suction filtration and wash it with deionized water until the conductivity of the filtrate is less than , obtaining a precipitate. Then, sequentially perform alcohol washing, drying, grinding, and sieving on the obtained precipitate, and finally obtain birnessite powder;

[0037] Specifically, leave the suspension obtained in S2 still in a constant-temperature oven at 60 °C, then perform suction filtration and wash it with deionized water until the conductivity of the filtrate is less than , obtaining a precipitate. Then, sequentially perform alcohol washing, drying, grinding, and sieving on the obtained precipitate, and finally obtain birnessite powder.

[0038] S4. Add the birnessite powder obtained in S3 into a conical flask, then add a complexing agent solution for mixing, and modify the surface of birnessite through a complexation reaction to obtain a complexation-modified birnessite catalyst; the complexing agent is ethylenediaminetetraacetic acid or diethylenetriaminepentaacetic acid; the molar ratio of birnessite powder to the complexing agent is 1 - 6:1.

[0039] The present invention also discloses a complexation-modified birnessite catalyst.

[0040] The present invention also discloses a method for activating PAA by a complexation-modified birnessite catalyst to degrade organic pollutants, which specifically includes the following steps:

[0041] A1. Add a complexation-modified birnessite catalyst and peracetic acid to a polluted water body containing organic pollutants to obtain a mixed water body; the concentration of the complexation-modified birnessite catalyst is 0.025 g / L - 0.1 g / L; the organic pollutant is sulfamethoxazole (SMX) or sulfadiazine (SD) in sulfonamide drugs; the concentration of peracetic acid in the mixed water body in A1 is 0.5 mM - 5 mM;

[0042] A2. Adjust the pH of the mixed water body with an acid or a base, and perform a degradation reaction under normal temperature and pressure to obtain a degraded reaction solution; the degradation reaction is carried out under the condition that the pH is 3 - 9.

[0043] Specifically, first add a complexation-modified birnessite catalyst with a concentration of 0.025 g / L - 0.1 g / L and peracetic acid with a concentration of 0.5 mM - 5 mM to a polluted water body containing sulfamethoxazole (SMX) to obtain a mixed water body; then adjust the pH of the mixed water body with an acid or a base, and perform a degradation reaction under normal temperature and pressure to obtain a degraded reaction solution; finally, measure the content of sulfamethoxazole (SMX) in the degraded reaction solution by liquid chromatography to obtain the degradation efficiency of SMX in the polluted water body. The acid is at least one of hydrochloric acid, nitric acid, and sulfuric acid; the base is sodium hydroxide or potassium hydroxide.

[0044] Comparative Example 1:

[0045] Using birnessite powder material alone as a catalyst, the removal effect of activated peracetic acid on SMX by birnessite powder alone was tested through the change in the peak area of SMX in liquid chromatography. The specific steps are as follows:

[0046] (1) Preparation of the birnessite catalyst: Stir and heat 300 mL of potassium permanganate solution with a concentration of to 100 °C, and use a constant flow pump to gradually add 45 mL of hydrochloric acid solution with a concentration of to the potassium permanganate solution at a rate of . After the addition is complete, continue the reaction for 30 min to obtain a suspension; then place the obtained suspension in a constant temperature oven at 60 °C and let it stand for 12 h, then perform suction filtration and wash with deionized water until the conductivity of the filtrate is less than to obtain a precipitate; wash the precipitate 3 times with ethanol and then dry it in a blast drying oven. After drying, grind it and pass it through a 100-mesh sieve to obtain birnessite powder;

[0047] (2) Prepare 20 mg / L SMX solution and 50 mM peracetic acid solution for standby;

[0048] (3) Use a conical flask as the reactor. Add 10 mL of 20 mg / L SMX solution, 1 mL of 50 mM peracetic acid solution, and deionized water to the reactor in sequence, keeping the volume of the solution in the reactor at 20 mL. At the same time, add 1 mg of birnessite powder catalyst. The concentration of SMX in pharmaceutical wastewater is relatively high, and the wastewater is usually acidic due to the use of acidic solvents in the production process. Therefore, adjust the initial pH of the solution in the reactor to 3.

[0049] For comparison, take another two groups of reactors. One group of reactors does not add birnessite powder catalyst, and the other group does not add peracetic acid solution. Place each conical flask in a shaker at 150 rpm and carry out the reaction at room temperature, and conduct fixed-point sampling analysis.

[0050] In the above three different reaction systems, the removal rates of SMX are shown in the following table:

[0051] Table 1: Removal rates of SMX under different reaction systems

[0052]

[0053] As can be seen from Table 1: When adding birnessite catalyst or peracetic acid alone, the degradation rate of SMX is relatively low (less than 5%); while when adding birnessite catalyst and peracetic acid simultaneously, the degradation efficiency of SMX is significantly improved. After 1440 min, the degradation efficiency of SMX reaches 94.0%, indicating that peracetic acid has a good removal effect on SMX under the catalytic activation of birnessite.

[0054] The as-prepared birnessite powder catalyst was characterized by scanning electron microscopy (SEM). As Figure 1 shown, the catalyst as a whole presents a nano-flower-like spherical aggregate. It can be seen that the catalyst aggregate has a typical nano-layered structure, consisting of manganese oxide octahedral layers and interlayer domains. In the manganese oxide octahedral layers, manganese ions form octahedral coordination structures with oxygen ions, and these octahedrons are connected to each other by sharing edges or corners to form a two-dimensional layered structure; water molecules and cations can be accommodated in the interlayer domains, and the presence of these interlayer substances has an important impact on the structure and properties of birnessite.

[0055] The birnessite powder catalyst before and after the reaction with SMX was characterized by X-ray diffraction (XRD). As Figure 2 shown, it can be seen that the peak positions of the catalyst are in good agreement with those of the PDF card JCPDS No. 00-013-0105, which indicates that the crystal structure of the catalyst is consistent with the crystal structure of the substance corresponding to JCPDS No. 00-013-0105, indicating that the prepared catalyst is birnessite with a specific crystal structure.

[0056] By comparing the XRD patterns before the reaction (black curve) and after the reaction (red curve), it can be found that the peak positions basically do not change. This means that during the SMX reaction process, the crystal structure of the birnessite powder catalyst remains relatively stable, without obvious phase changes or major changes in the crystal structure, indicating that the catalyst has stability, which helps to maintain the active sites of the catalyst and can be recycled.

[0057] Comparative Example 2:

[0058] Using the birnessite powder obtained in Comparative Example 1 as the catalyst, the removal effect of activated peracetic acid on SMX by the birnessite powder catalyst under different catalyst dosages (0.5 mg, 1 mg, 2 mg) was studied by the change in the SMX peak area in liquid chromatography.

[0059] (1) Preparation of the birnessite catalyst: Stir and heat 300 mL of potassium permanganate solution with a concentration of to 100 °C, and use a constant flow pump to dropwise add 45 mL of hydrochloric acid solution with a concentration of into the potassium permanganate solution at a rate of . After the addition is complete, continue the reaction for 30 min to obtain a suspension; then place the obtained suspension in a constant temperature oven at 60 °C and let it stand for 12 h, then perform suction filtration and wash with deionized water until the conductivity of the filtrate is less than to obtain a precipitate; wash the precipitate 3 times with ethanol and then dry it in a blast drying oven, grind it after drying and pass it through a 100-mesh sieve to obtain birnessite powder;

[0060] (2)Prepare 20 mg / L SMX solution and 50 mM peracetic acid solution for standby;

[0061] (3)Use conical flasks as reactors. Sequentially add 10 mL of 20 mg / L SMX solution, 1 mL of 50 mM peracetic acid solution, and deionized water to each reactor, keeping the volume of the solution in the reactor at 20 mL. At the same time, add 0.5 mg, 1 mg, and 2 mg of birnessite powder catalyst to each reactor, so that the concentrations of birnessite powder catalyst in each reactor are 0.025 g / L, 0.05 g / L, and 0.1 g / L respectively. Adjust the initial pH of the solution to 3. Place each conical flask in a shaker at 150 rpm and carry out the reaction at room temperature, and take fixed-point samples for analysis.

[0062] The removal rates of SMX under the above three different catalyst dosages are shown in the following table:

[0063] Table 2: Removal rates of SMX under different catalyst dosages

[0064]

[0065] As can be seen from Table 2: At 1440 min, when the concentrations of birnessite powder catalyst in the reaction system are 0.025 mg / L, 0.05 mg / L, and 0.1 mg / L respectively, the degradation efficiencies of SMX are 68.8%, 94.1%, and 73.3% respectively. It can be seen that as the catalyst dosage increases from 0.5 mg to 2 mg, the degradation efficiency of SMX at 1440 min of the reaction shows a trend of first increasing and then decreasing. Among them, when the dosage of birnessite is 1 mg, the degradation effect is the best, up to 94.1%.

[0066] Comparative Example 3:

[0067] Using the birnessite powder obtained in Comparative Example 1 as the catalyst, study the removal effect of the activation of peracetic acid by birnessite powder catalyst on SMX under different peracetic acid dosages (0.2 mL, 0.4 mL, 1 mL, 2 mL) through the change of the SMX peak area in liquid chromatography.

[0068] (1)Preparation of birnessite catalyst: Stir and heat 300 mL of potassium permanganate solution with a concentration of to 100 °C, and use a constant flow pump to add 45 mL of hydrochloric acid solution with a concentration of dropwise into the potassium permanganate solution at a rate. After the addition is complete, continue the reaction for 30 min to obtain a suspension; then place the obtained suspension in a constant temperature oven at 60 °C and let it stand for 12 h, and then carry out suction filtration and wash with deionized water until the conductivity of the filtrate is less than , a precipitate was obtained; the precipitate was washed 3 times with ethanol and then dried in a forced-air oven, ground after drying and passed through a 100-mesh sieve to obtain birnessite powder;

[0069] (2) Prepare 20 mg / L SMX solution and 50 mM peracetic acid solution for standby;

[0070] (3) Use conical flasks as reactors, add 10 mL of 20 mg / L SMX solution and deionized water to each reactor in sequence. At the same time, add 0.2 mL, 0.4 mL, 1 mL, and 2 mL of 50 mM peracetic acid solution to each reactor respectively, so that the concentrations of peracetic acid solution in each reactor are 0.5 mM, 1 mM, 2.5 mM, and 5 mM respectively. Keep the volume of the solution in the reactor at 20 mL, then add 1 mg of birnessite powder catalyst, and adjust the initial pH of the solution to 3. Place each conical flask in a shaker at 150 rpm and carry out the reaction at room temperature, and take samples at fixed points for analysis.

[0071] The removal rates of SMX at different dosages of peracetic acid are shown in the following table:

[0072] Table 3: Removal rates of SMX at different concentrations of peracetic acid

[0073]

[0074] As can be seen from Table 3: at 1440 min, when 0.2 mL, 0.4 mL, 1 mL, and 2.0 mL of peracetic acid were added, the corresponding degradation efficiencies of SMX were 10.4%, 55.0%, 94.3%, and 84.2% respectively. Thus, it can be seen that as the dosage of peracetic acid increased from 0.2 mL to 2.0 mL, the overall degradation efficiency of SMX showed an upward trend. Among them, when the dosage of peracetic acid was 1.0 mL, the degradation efficiency of SMX was the highest.

[0075] Comparative Example 4:

[0076] Using the birnessite powder obtained in Comparative Example 1 as a catalyst, the effect of the activation of peracetic acid by the birnessite powder catalyst on the degradation of SMX at different initial solution pH values (pH = 3, pH = 5, pH = 7, pH = 9) was studied by the change in the peak area of SMX in liquid chromatography.

[0077] (1) Preparation of birnessite catalyst: Stir and heat 300 mL of potassium permanganate solution with a concentration of to 100 °C, and use a constant flow pump to add 45 mL of hydrochloric acid solution with a concentration of at a rate of The potassium permanganate solution was added dropwise at a rate, and after the addition was completed, the reaction was continued for 30 min to obtain a suspension; subsequently, the obtained suspension was placed in a constant temperature oven at 60 °C and left standing for 12 h, then filtered by suction and washed with deionized water until the conductivity of the filtrate was less than , to obtain a precipitate; the precipitate was washed 3 times with ethanol and then dried in a blast drying oven, ground after drying and passed through a 100-mesh sieve to obtain birnessite powder;

[0078] (2) Prepare 20 mg / L SMX solution and 50 mM peracetic acid solution for standby;

[0079] (3) Using conical flasks as reactors, 10 mL of 20 mg / L SMX solution, 1 mL of 50 mM peracetic acid solution and deionized water were successively added to each reactor, keeping the volume of the solution in the reactor at 20 mL. At the same time, 1 mg of birnessite powder catalyst was added to each reactor, and the initial pH of the solution was adjusted to 3, 5, 7, and 9 respectively. Each conical flask was placed in a shaker at 150 rpm and reacted at room temperature, and fixed-point sampling analysis was carried out.

[0080] The removal rates of SMX under different initial pH conditions are shown in the following table:

[0081] Table 4: Removal rates of SMX at different initial pH values of the solution

[0082]

[0083] As can be seen from Table 4: at 1440 min, when the initial pH of the solution was 3, 5, 7, and 9, the degradation efficiencies of SMX were 91.1%, 70.2%, 46.7%, and 25.7% respectively. As the initial pH of the solution increased from 3 to 9, the degradation efficiency of SMX showed a downward trend, decreasing from 94.1% to 25.7%. Therefore, the catalytic effect of the birnessite powder catalyst is better under acidic conditions, and the degradation efficiency of SMX is the highest when pH = 3.

[0084] Example 1:

[0085] A method for complex-modified birnessite-activated PAA to degrade organic pollutants:

[0086] Using EDTA complex-modified birnessite as a catalyst, the removal effect of EDTA complex-modified birnessite catalyst-activated peracetic acid on SMX was tested by the change of the SMX peak area in liquid chromatography at different catalyst dosages (0.5 mg, 1 mg, 2 mg). The specific steps are as follows:

[0087] (1) Preparation of EDTA complex-modified birnessite catalyst: 300 mL of a solution with a concentration of The potassium permanganate solution was stirred and heated to 100 °C. 45 mL of hydrochloric acid solution with a concentration of was added dropwise to the potassium permanganate solution at a rate of using a constant flow pump. After the addition was complete, the reaction continued for 30 min to obtain a suspension. Subsequently, the obtained suspension was placed in a 60 °C constant temperature oven and left standing for 12 h, then filtered by suction and washed with deionized water until the conductivity of the filtrate was less than , to obtain a precipitate. The precipitate was washed three times with ethanol and then dried in a forced air oven. After drying, it was ground and passed through a 100-mesh sieve to obtain birnessite powder. 0.5 mg, 1 mg, and 2 mg of birnessite powder were respectively mixed with 2 mL of 1.8 mM EDTA, and the surface of the birnessite powder was modified by complexation reaction to obtain three kinds of complex-modified birnessite catalysts with molar ratios of 1.5:1, 3:1, and 6:1;

[0088] (2) Prepare 20 mg / L SMX solution and 50 mM peracetic acid solution for standby;

[0089] (3) Using conical flasks as reactors, 10 mL of 20 mg / L SMX solution, 1.0 mL of 50 mM peracetic acid solution, and deionized water were successively added to each reactor. At the same time, the above three kinds of EDTA complex-modified birnessite catalysts were respectively added to each reactor, keeping the volume of the solution in the reactor at , and adjusting the initial pH of the solution to 3. The conical flasks were placed in a shaker at 150 rpm and the reaction was carried out at room temperature, and fixed-point sampling analysis was carried out.

[0090] The removal rates of SMX under the above three different catalyst dosages are shown in the following table:

[0091] Table 5: Removal rates of SMX under different catalyst dosages

[0092]

[0093] As can be seen from Table 5, the efficiency of birnessite activated peracetic acid to degrade SMX after EDTA complex modification has been greatly improved, and the reaction time has been shortened from 1440 min to 120 min. After 120 min of reaction, when the content of the complex-modified birnessite catalyst in the reaction system was 0.025 g / L, 0.05 g / L, and 0.1 g / L, the corresponding degradation efficiencies of SMX were 71.7%, 94.4%, and 58.32% respectively. Thus, it can be seen that as the catalyst dosage increased from 0.5 mg to 2 mg, the degradation efficiency of SMX at 120 min of reaction showed a trend of first increasing and then decreasing. Considering from the aspects of reaction efficiency and cost, when the dosage of birnessite was 1 mg, the catalytic effect was the best, that is, when the molar ratio of birnessite to the complexing agent EDTA was 3:1, the degradation rate of SMX was the fastest, and the reaction rate constant k obs was , which is 100 times that of using birnessite alone as a catalyst for k obs .

[0094] Complexing agents can prevent the structural collapse or dissolution of birnessite catalysts during the reaction process and extend their service life. The complexing agent-modified birnessite catalyst prepared by the post-treatment method has the advantages of simple operation and flexible adjustment of the type of complexing agent compared with the co-precipitation method, and can select a suitable complexing agent according to the pollution status of organic polluted water bodies.

[0095] The reaction equation for the degradation of SMX by the complexing agent-modified birnessite catalyst is as follows:

[0096]

[0097] It can be seen from the above reaction equation that the efficient degradation of SMX by the complexing agent-modified birnessite catalyst activating PAA is achieved through a free radical pathway mainly based on acetylperoxy radicals and superoxide radicals and a non-free radical pathway mainly based on singlet oxygen.

[0098] Example 2:

[0099] This example provides a technical solution based on Example 1: A method for degrading organic pollutants by activating PAA with a complexing agent-modified birnessite. Using the DTPA-complexed birnessite as a catalyst, the removal effect of the DTPA-complexed birnessite catalyst activating peracetic acid on SMX was tested by the change in the peak area of SMX in liquid chromatography at different molar ratios of birnessite powder to DTPA (1.5:1, 3:1, 6:1). The specific steps are as follows:

[0100] (1) Preparation of the DTPA-complexed birnessite catalyst: Stir and heat 300 mL of a potassium permanganate solution with a concentration of to 100 °C, and use a constant flow pump to add 45 mL of a hydrochloric acid solution with a concentration of dropwise into the potassium permanganate solution at a rate of . After the addition is complete, continue the reaction for 30 min to obtain a suspension; then place the obtained suspension in a constant temperature oven at 60 °C and let it stand for 12 h, then perform suction filtration and wash it with deionized water until the conductivity of the filtrate is less than to obtain a precipitate; wash the precipitate 3 times with ethanol and then dry it in a blast drying oven. After drying, grind it and pass it through a 100-mesh sieve to obtain birnessite powder; respectively mix 0.5 mg, 1 mg, and 2 mg of birnessite powder with 2 mL of DTPA with a concentration of 1.8 mM, so that the molar ratios of birnessite powder to DTPA are 1.5:1, 3:1, and 6:1 respectively, and modify the surface of the birnessite powder through a complexation reaction to obtain three complexing agent-modified birnessite catalysts with molar ratios of 1.5:1, 3:1, and 6:1 respectively;

[0101] (2) Prepare 20 mg / L SMX solution and 50 mM peracetic acid solution for later use;

[0102] (3) Use conical flasks as reactors. Add 10 mL of 20 mg / L SMX solution, 1.0 mL of 50 mM peracetic acid solution and deionized water to each reactor in sequence. At the same time, add the above three kinds of DTPA-complex modified birnessite catalysts to each reactor, keep the volume of the solution in the reactor at 20 mL, and adjust the initial pH of the solution to 3. Place the conical flasks in a shaker at 150 rpm and carry out the reaction at room temperature, and take samples at fixed points for analysis.

[0103] The removal rates of SMX under different molar ratios of DTPA-complex modified birnessite catalysts are shown in the following table:

[0104] Table 6: Removal rates of SMX under different molar ratios of DTPA-complex modified birnessite

[0105]

[0106] As can be seen from Table 6: At 120 min, DTPA-complex modified birnessite catalysts with different molar ratios (1.5:1, 3:1, 6:1) all have good removal effects on SMX and can completely degrade SMX in the solution. Thus, it can be seen that as the molar ratio of birnessite to DTPA increases, the degradation rate of SMX gradually decreases. Considering the reaction efficiency and cost, when the dosage of birnessite is 0.5 mg, that is, when the molar ratio of birnessite to DTPA complexing agent is 1.5:1, the catalytic effect is the best and the degradation rate of SMX is the fastest.

[0107] Example 3:

[0108] This example provides a technical solution on the basis of Example 1: A method for degrading organic pollutants by complex modified birnessite activating PAA. Using the EDTA-complex modified birnessite with a molar ratio of 3:1 obtained in Example 1 as a catalyst, study the removal effect of EDTA-complex modified birnessite catalyst activating peracetic acid on SMX under different peracetic acid dosages (0.2 mL, 0.4 mL, 1 mL, 2 mL) through the change of the SMX peak area in liquid chromatography. The specific steps are as follows:

[0109] (1) Preparation of EDTA-complex modified birnessite catalyst: Stir and heat 300 mL of potassium permanganate solution with a concentration of to 100 °C, and use a constant flow pump to add 45 mL of hydrochloric acid solution with a concentration of at The potassium permanganate solution was added dropwise at a rate, and after the addition was complete, the reaction continued for 30 min to obtain a suspension; subsequently, the obtained suspension was placed in a constant-temperature oven at 60 °C and left standing for 12 h, then filtered by suction and washed with deionized water until the conductivity of the filtrate was less than , and a precipitate was obtained; the precipitate was washed 3 times with ethanol and then dried in a forced-air oven, ground after drying and passed through a 100-mesh sieve to obtain birnessite powder; 1 mg of birnessite powder was mixed with 2 mL of EDTA with a concentration of 1.8 mM, and the surface of the birnessite powder was modified by a complexation reaction to obtain an EDTA complex-modified birnessite catalyst with a molar ratio of 3:1;

[0110] (2) Prepare 20 mg / L SMX solution and 50 mM peracetic acid solution for later use;

[0111] (3) Using conical flasks as reactors, 10 mL of 20 mg / L SMX solution and deionized water were successively added to each reactor. At the same time, 0.2 mL, 0.4 mL, 1 mL, and 2 mL of 50 mM peracetic acid solution were respectively added to each reactor, so that the concentrations of peracetic acid solution in each reactor were 0.5 mM, 1 mM, 2.5 mM, and 5 mM. Then, the above-mentioned EDTA complex-modified birnessite catalyst was respectively added to each reactor, keeping the volume of the solution in the reactor at 20 mL, and adjusting the initial pH of the solution to 3. Each conical flask was placed in a shaker at 150 rpm and the reaction was carried out at room temperature, and fixed-point sampling analysis was performed.

[0112] The removal rates of SMX at different peracetic acid dosages are shown in the following table:

[0113] Table 7: Removal rates of SMX at different peracetic acid concentrations

[0114]

[0115] It can be seen from Table 7 that at 120 min, when 0.2 mL, 0.4 mL, 1 mL, and 2.0 mL of peracetic acid were added, the corresponding degradation efficiencies of SMX were 68.1%, 71.1%, 94.1%, and 94.3% respectively. From the test results, as the concentration of peracetic acid increased from 0.2 mL to 2.0 mL, the overall degradation efficiency of the EDTA complex-modified birnessite catalyst for SMX showed an upward trend. Considering the reaction efficiency and cost, a peracetic acid dosage of 1.0 mL was the best choice.

[0116] Example 4:

[0117] On the basis of Example 1, this example provides a technical solution: a method for activating PAA by complex modified birnessite to degrade organic pollutants. Using the EDTA complex modified birnessite with a molar ratio of 3:1 obtained in Example 1 as a catalyst, the effect of the EDTA complex modified birnessite catalyst activating peracetic acid on the degradation of SMX under different initial solution pH values (pH = 3, pH = 5, pH = 7, pH = 9) was studied by the change in the peak area of SMX in liquid chromatography. The specific steps are as follows:

[0118] (1) Preparation of the EDTA complex modified birnessite catalyst: Stir and heat 300 mL of potassium permanganate solution with a concentration of to 100 °C. Use a constant flow pump to dropwise add 45 mL of hydrochloric acid solution with a concentration of into the potassium permanganate solution at a rate of . After the addition is complete, continue the reaction for 30 min to obtain a suspension; then place the obtained suspension in a 60 °C constant temperature oven and let it stand for 12 h, then perform suction filtration and wash with deionized water until the conductivity of the filtrate is less than to obtain a precipitate; wash the precipitate 3 times with ethanol and then dry it in a blast drying oven. After drying, grind it and pass it through a 100-mesh sieve to obtain birnessite powder; mix 1 mg of birnessite powder with 2 mL of 1.8 mM EDTA, and modify the surface of the birnessite powder through a complexation reaction to obtain an EDTA complex modified birnessite catalyst with a molar ratio of 3:1;

[0119] (2) Prepare 20 mg / L SMX solution and 50 mM peracetic acid solution for standby;

[0120] (3) Use conical flasks as reactors. Add 10 mL of 20 mg / L SMX solution, 1 mL of 50 mM peracetic acid solution and deionized water to each reactor in turn. At the same time, add the above-mentioned EDTA complex modified birnessite catalyst to each reactor, keep the volume of the solution in the reactor at 20 mL, and adjust the initial pH of the solution to 3, 5, 7, and 9 respectively. Place each conical flask in a shaker at 150 rpm and carry out the reaction at room temperature, and take samples at fixed points for analysis.

[0121] The removal rates of SMX at different initial solution pH values are shown in the following table:

[0122] Table 8: Removal rates of SMX at different initial solution pH values

[0123]

[0124] As can be seen from Table 8: At 120 min, when the initial pH of the solution was pH = 3, pH = 5, pH = 7, and pH = 9 respectively, the degradation efficiencies of SMX were 94.3%, 71.1%, 61.6%, and 29.1% respectively. As the initial pH of the solution increased from 3 to 9, the degradation efficiency of SMX showed a downward trend, decreasing from 94.3% to 29.1%. It can be seen that the EDTA-complex modified birnessite catalyst has better catalytic effect under acidic conditions, and among them, pH = 3 is the optimal reaction condition.

[0125] Example 5:

[0126] Based on Example 1, this example provides a technical solution: A method for complex-modifying birnessite to activate PAA for degrading organic pollutants. Using the EDTA-complex modified birnessite with a molar ratio of 3:1 obtained in Example 1 as the catalyst, the degradation effect of the EDTA-complex modified birnessite catalyst activating peracetic acid on SMX was studied by the change of the SMX peak area in liquid chromatography under different dosages of humic acid (HA) (0.2 mg, 2 mg, 10 mg) in the reaction system. The specific steps are as follows:

[0127] (1) Preparation of the EDTA-complex modified birnessite catalyst: Stir and heat 300 mL of potassium permanganate solution with a concentration of to 100 °C, and use a constant flow pump to add 45 mL of hydrochloric acid solution with a concentration of dropwise into the potassium permanganate solution at a rate of . After the dropping is completed, continue the reaction for 30 min to obtain a suspension; then place the obtained suspension in a constant temperature oven at 60 °C and let it stand for 12 h, then carry out suction filtration and wash it with deionized water until the conductivity of the filtrate is less than to obtain a precipitate; wash the precipitate 3 times with ethanol and then dry it in a blast drying oven. After drying, grind it and pass it through a 100-mesh sieve to obtain birnessite powder; mix 1 mg of birnessite powder with 2 mL of 1.8 mM EDTA, and modify the surface of the birnessite powder through a complexation reaction to obtain an EDTA-complex modified birnessite catalyst with a molar ratio of 3:1;

[0128] (2) Prepare 20 mg / L SMX solution and 50 mM peracetic acid solution for standby;

[0129] (3) Using a conical flask as the reactor, 10 mL of 20 mg / L SMX solution, 1 mL of 50 mM peracetic acid solution, the above-mentioned EDTA-complex modified birnessite catalyst, and deionized water were successively added to each reactor, keeping the volume of the solution in the reactor at 20 mL. At the same time, 0 mg, 0.2 mg, 2 mg, and 10 mg of humic acid were added to each reactor respectively, and the initial pH of the solution was adjusted to 3. Each conical flask was placed in a shaker at 150 rpm and reacted at room temperature, and samples were taken at fixed points for analysis.

[0130] The removal rates of SMX at the above different dosages of HA are shown in the following table:

[0131] Table 9: Removal rates of SMX at different dosages of HA

[0132]

[0133] It can be seen from Table 9 that as the dosage of HA increases, the removal rate of SMX decreases slightly, indicating that the presence of HA in the solution will have a certain inhibitory effect on the degradation of SMX.

[0134] Example 6:

[0135] This example provides a technical solution on the basis of Example 1: A method for complex-modified birnessite-activated PAA to degrade organic pollutants. Using the EDTA-complex modified birnessite with a molar ratio of 3:1 obtained in Example 1 as the catalyst, the degradation effect of EDTA-complex modified birnessite catalyst-activated peracetic acid on SMX at different concentrations of coexisting anions (Cl - ) (0 mmol / L, 5 mmol / L, 50 mmol / L, 100 mmol / L) in the reaction solution was studied by the change of the SMX peak area in liquid chromatography. The specific steps are as follows:

[0136] (1) Preparation of EDTA-complex modified birnessite catalyst: Stir and heat 300 mL of potassium permanganate solution with a concentration of to 100 °C, and use a constant flow pump to add 45 mL of hydrochloric acid solution with a concentration of dropwise into the potassium permanganate solution at a rate of , and continue to react for 30 min after dropping to obtain a suspension; then place the obtained suspension in a constant temperature oven at 60 °C and let it stand for 12 h, and then perform suction filtration and wash with deionized water until the conductivity of the filtrate is less than , a precipitate is obtained; the precipitate is washed three times with ethanol and then dried in a forced-air oven, ground after drying and passed through a 100-mesh sieve to obtain birnessite powder; 1 mg of birnessite powder is mixed with 2 mL of 1.8 mM EDTA, and the surface of the birnessite powder is modified through a complexation reaction to obtain an EDTA complex-modified birnessite catalyst with a molar ratio of 3:1;

[0137] (2) Prepare 20 mg / L SMX solution, 50 mM peracetic acid solution and 1 mol / L NaCl solution for standby;

[0138] (3) Use a conical flask as the reactor, and sequentially add 10 mL of 20 mg / L SMX solution, 1 mL of 50 mM peracetic acid solution, the above-mentioned EDTA complex-modified birnessite catalyst and deionized water to each reactor. At the same time, add 0 mL, 0.1 mL, 1 mL, 2 mL of 1 mol / L NaCl solution to each reactor respectively. At this time, the coexisting anions in each reactor have concentrations of 0 mmol / L, 5 mmol / L, 50 mmol / L, 100 mmol / L respectively. Keep the volume of the solution in the reactor at 20 mL and adjust the initial pH of the solution to 3. Place each conical flask in a shaker at 150 rpm and carry out the reaction at room temperature, and take samples at fixed points for analysis.

[0139] Above at different concentrations, the removal rates of SMX are shown in the following table:

[0140] Table 10: Removal rates of SMX at different concentrations

[0141]

[0142] As can be seen from Table 10: With the addition of , the removal rate of SMX by the EDTA complex-modified birnessite catalyst activating peracetic acid hardly changes, indicating that the presence of in the solution has no significant effect on the degradation of SMX.

[0143] Example Seven:

[0144] This example provides a technical solution on the basis of Example One: A method for degrading organic pollutants by complex-modified birnessite activating PAA. Using the EDTA complex-modified birnessite with a molar ratio of 3:1 obtained in Example One as the catalyst, different coexisting anions in the reaction solution are studied through the change of the SMX peak area in liquid chromatography Degradation effects of EDTA-complexed modified birnessite catalyst activating peracetic acid on SMX at different concentrations (0 mmol / L, 5 mmol / L, 50 mmol / L, 100 mmol / L). The specific steps are as follows:

[0145] (1) Preparation of EDTA-complexed modified birnessite catalyst: Stir and heat 300 mL of potassium permanganate solution with a concentration of to 100 °C, and use a constant flow pump to gradually add 45 mL of hydrochloric acid solution with a concentration of into the potassium permanganate solution at a rate of . After the addition is complete, continue the reaction for 30 min to obtain a suspension; then place the obtained suspension in a constant temperature oven at 60 °C and let it stand for 12 h, then perform suction filtration and wash with deionized water until the conductivity of the filtrate is less than to obtain a precipitate; wash the precipitate 3 times with ethanol and dry it in a blast drying oven. After drying, grind it and pass through a 100-mesh sieve to obtain birnessite powder; mix 1 mg of birnessite powder with 2 mL of 1.8 mM EDTA, and modify the surface of the birnessite powder through a complexation reaction to obtain an EDTA-complexed modified birnessite catalyst with a molar ratio of 3:1;

[0146] (2) Prepare 20 mg / L SMX solution, 50 mM peracetic acid solution, and 1 mol / L NaHCO3 solution for standby;

[0147] (3) Use conical flasks as reactors. Add 10 mL of 20 mg / L SMX solution, 1 mL of 50 mM peracetic acid solution, the above-mentioned EDTA-complexed modified birnessite catalyst, and deionized water to each reactor in sequence. At the same time, add 0 mL, 0.1 mL, 1 mL, and 2 mL of 1 mol / L NaHCO3 solution to each reactor respectively. At this time, the concentrations of coexisting anions in each reactor are 0 mmol / L, 5 mmol / L, 50 mmol / L, and 100 mmol / L respectively. Keep the volume of the solution in the reactor at 20 mL and adjust the initial pH of the solution to 3. Place each conical flask in a shaker at 150 rpm and carry out the reaction at room temperature, and take samples at fixed points for analysis.

[0148] The removal rates of SMX at the above different concentrations are shown in the following table:

[0149] Table 11: Removal rates of SMX at different concentrations

[0150]

[0151] As can be seen from Table 11: As The addition of significantly inhibited the degradation of SMX by the EDTA-complex modified birnessite catalyst activating peracetic acid, and the inhibitory effect on the degradation of SMX was more obvious at high concentrations of The inhibitory effect on the degradation of SMX was more obvious.

[0152] Example VIII:

[0153] Based on Example I, this example provides a technical solution: a method for the complex modified birnessite to activate PAA to degrade organic pollutants. Using the EDTA-complex modified birnessite with a molar ratio of 3:1 obtained in Example I as the catalyst, the degradation effect of the EDTA-complex modified birnessite catalyst activating peracetic acid on SMX was studied by the change of the SMX peak area in liquid chromatography under different coexisting anions concentrations (0 mmol / L, 5 mmol / L, 50 mmol / L, 100 mmol / L). The specific steps are as follows:

[0154] (1) Preparation of the EDTA-complex modified birnessite catalyst: Stir and heat 300 mL of a potassium permanganate solution with a concentration of to 100 °C, and use a constant flow pump to gradually add 45 mL of a hydrochloric acid solution with a concentration of to the potassium permanganate solution at a rate of . After the addition is complete, continue the reaction for 30 min to obtain a suspension; then place the obtained suspension in a 60 °C constant temperature oven and let it stand for 12 h, then perform suction filtration and wash with deionized water until the conductivity of the filtrate is less than to obtain a precipitate; wash the precipitate 3 times with ethanol and then dry it in a blast drying oven. After drying, grind it and pass it through a 100-mesh sieve to obtain birnessite powder; mix 1 mg of birnessite powder with 2 mL of 1.8 mM EDTA, and modify the surface of the birnessite powder through a complexation reaction to obtain an EDTA-complex modified birnessite catalyst with a molar ratio of 3:1;

[0155] (2) Prepare 20 mg / L SMX solution, 50 mM peracetic acid solution and 1 mol / L Na2SO4 solution for standby;

[0156] (3) Use conical flasks as reactors, and sequentially add 10 mL of 20 mg / L SMX solution, 1 mL of 50 mM peracetic acid solution, the above-mentioned EDTA-complex modified birnessite catalyst and deionized water to each reactor. At the same time, add 0 mL, 0.1 mL, 1 mL, 2 mL of 1 mol / L Na2SO4 solution to each reactor respectively. At this time, the coexisting anions in each reactor The concentrations were 0 mmol / L, 5 mmol / L, 50 mmol / L, and 100 mmol / L respectively. The volume of the solution in the reactor was maintained at 20 mL, and the initial pH of the solution was adjusted to 3. Each conical flask was placed in a shaker at 150 rpm and reacted at room temperature, and samples were taken at fixed points for analysis.

[0157] At the above different concentrations, the removal rates of SMX are shown in the following table:

[0158] Table 12: Removal rates of SMX at different concentrations

[0159]

[0160] As can be seen from Table 12: There is a certain inhibitory effect on the activation of peracetic acid by the EDTA-complexed and modified birnessite catalyst to degrade SMX. When is added, the degradation rate of SMX decreases from 94.4% to 64.1%. With the increase of the ion concentration, the inhibitory effect on the degradation of SMX gradually increases.

[0161] Only some exemplary embodiments of the present invention have been described by way of illustration above. Undoubtedly, for those of ordinary skill in the art, without departing from the spirit and scope of the present invention, the described embodiments can be modified in various different ways. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the protection scope of the claims of the present invention.

Claims

1. A preparation method of a complex-modified birnessite catalyst, characterized in that, Specifically, it includes the following steps: S1. Prepare a potassium permanganate aqueous solution with a concentration of 0.5 - 1 mol·L -1 and a hydrochloric acid aqueous solution with a concentration of 1 - 6 mol·L -1 for standby; S2. Add the potassium permanganate aqueous solution prepared in S1 into a beaker, stir and heat it, and then use a constant flow pump to gradually add the hydrochloric acid aqueous solution prepared in S1 drop by drop into the heated potassium permanganate solution. After the addition is completed, react for 30 - 60 min to obtain a suspension; S3. Leave the suspension obtained in S2 standing in a constant-temperature oven, then perform suction filtration and wash with deionized water until the conductivity of the filtrate is less than 10 μS·cm -1 , to obtain a precipitate. Then, successively perform alcohol washing, drying, grinding, and sieving on the obtained precipitate, and finally obtain birnessite powder; S4. Add the birnessite powder obtained in S3 into a conical flask, and then add a complexing agent, ethylenediaminetetraacetic acid solution or diethylenetriaminepentaacetic acid solution, for mixing. The molar ratio of the birnessite powder to the complexing agent is 1 - 6:

1. Modify the surface of the birnessite through a complexation reaction to obtain a complexation - modified birnessite catalyst.

2. The preparation method of a complex-modified birnessite catalyst according to claim 1, characterized in that, The heating temperature in S2 is 80 - 100 °C.

3. The preparation method of a complex-modified birnessite catalyst according to claim 1, characterized in that, In S3, let the suspension stand in a constant - temperature oven, and at this time, set the temperature of the oven to 50 - 80 °C; set the standing time to 10 - 18 h.

4. A complex-modified birnessite catalyst, characterized in that, It is prepared by the preparation method of a complexation - modified birnessite catalyst according to any one of claims 1 - 3.

5. A method for activating PAA by complex modified birnessite to degrade organic pollutants, characterized in that, Specifically, it includes the following steps: A1. Add the complexation - modified birnessite catalyst and peracetic acid as described in claim 4 into the polluted water body containing organic pollutants to obtain a mixed water body; A2. Adjust the pH of the mixed water body with an acid or a base, and carry out a degradation reaction under normal temperature and pressure to obtain a degraded reaction solution.

6. The method for activating PAA by complex modified birnessite to degrade organic pollutants according to claim 5, characterized in that In the mixed water body in A1, the concentration of the complexation - modified birnessite catalyst is 0.025 g / L - 0.1 g / L; the organic pollutant is a sulfonamide drug.

7. A method for activating PAA by complex-modified birnessite to degrade organic pollutants according to claim 6, characterized in that, In the mixed water body in A1, the concentration of peracetic acid is 0.5 mM - 5 mM.

8. A method for activating PAA by complex modified birnessite to degrade organic pollutants according to claim 7, characterized in that, The degradation reaction in A2 is carried out under the condition of pH 3 - 9.

Images