Method for degrading organic pollutants in water by using molybdenum disulfide activated potassium permanganate

Abstract

The application discloses a method for degrading organic pollutants in water by using molybdenum disulfide activated potassium permanganate, which comprises sequentially adding molybdenum disulfide powder and potassium permanganate into water containing trace organic pollutants, treating for 10-90 minutes, and then removing unreacted potassium permanganate and molybdenum disulfide powder through coagulation, sedimentation and filtration in sequence; when the concentration of the trace organic pollutants in the water is 0.1-5 muM, the adding amount of the potassium permanganate is 50-300 mu mol / L, and the adding amount of the molybdenum disulfide is 25-150 mg / L; when the concentration of the trace organic pollutants in the water is greater than 5 muM, the adding amount of the potassium permanganate is 150-500 mol / L, the adding amount of the molybdenum disulfide is 50-200 mg / L, and the adding ratio of the molybdenum disulfide to the potassium permanganate is 1:(0.4-0.8). The method can enhance the degradation capacity of the potassium permanganate by adding the molybdenum disulfide, improve the removal rate of the organic pollutants, reduce the adding amount of the potassium permanganate agent, finally reduce the cost of water treatment, and effectively alleviate the chroma problem caused by a high adding amount of the potassium permanganate.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, specifically relating to a method for degrading organic pollutants in water by activating potassium permanganate with molybdenum disulfide. Background Technology

[0002] However, with rapid social development and progress, high-risk and potentially environmentally polluting organic matter is being discharged into water bodies, causing water pollution and consequently harming the ecological environment and human health. Currently, the "new pollutants" posing significant threats to the ecological environment and human health mainly include four categories: persistent organic pollutants (POPs), endocrine disruptors, antibiotics, and microplastics. These pollutants are characterized by biotoxicity, environmental persistence, and bioaccumulation, and are not yet effectively regulated. Domestic and international research indicates that conventional drinking water treatment processes involving coagulation, sedimentation, filtration, and disinfection typically remove only 20-30% of organic pollutants from water. Furthermore, the presence of dissolved organic pollutants hinders the disruption of colloid stability, significantly reducing the effectiveness of conventional treatment processes in removing turbidity from raw water.

[0003] Advanced oxidation technology (AOP) is a highly efficient deep treatment technology for removing organic pollutants. Commonly used oxidants include ozone, persulfate, Fenton and Fenton-like systems, potassium permanganate, and potassium ferrate. Among these, potassium permanganate has the advantages of simple preparation, easy transportation and storage, low price, and convenient addition. In water treatment, it can effectively control the odor, color, and algae growth of water bodies, and it is often used as a green oxidant because it does not generate toxic or harmful byproducts during the oxidation process. However, potassium permanganate oxidation and degradation of organic matter has strong selectivity; it can only oxidize and remove organic matter containing unsaturated functional groups, and is less effective at degrading more difficult-to-degrade organic matter. Toxic and harmful organic pollutants have low reactivity, slow degradation rates, and poor removal efficiency. Achieving the same removal rate as strong oxidants requires a long time and large dosages, increasing the infrastructure and operating costs of engineering projects. Therefore, many studies have used potassium permanganate activation to improve its oxidation capacity, with commonly used catalysts such as sodium sulfite and UV. However, the addition ratio of sodium sulfite and potassium permanganate, as well as the pH value, have a significant impact on the activation performance of potassium permanganate. Furthermore, it is necessary to consider whether the sulfate concentration in the effluent after oxidation exceeds the standard. The application of UV-activated potassium permanganate in actual water bodies still needs further research. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a method for degrading organic pollutants in water by activating potassium permanganate with molybdenum disulfide. This method uses molybdenum disulfide as a catalyst to enhance the reaction rate between potassium permanganate and the target organic pollutants, thereby strengthening the treatment effect of organic pollutants and solving the technical problem of slow rate and low removal efficiency of potassium permanganate alone in the prior art for oxidizing and degrading organic matter in water.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for degrading organic pollutants in water by activating potassium permanganate with molybdenum disulfide includes sequentially adding molybdenum disulfide powder and potassium permanganate to water containing trace amounts of organic pollutants, treating for 10 to 90 minutes, and then sequentially removing unreacted potassium permanganate and molybdenum disulfide powder by coagulation, sedimentation and filtration after treatment.

[0007] When the concentration of trace organic pollutants in the water is 0.1–5 μM, the dosage of potassium permanganate is 50–300 μmol / L, and the dosage of molybdenum disulfide is 25–150 mg / L.

[0008] When the concentration of trace organic pollutants in water is >5 μM, the dosage of potassium permanganate is 150-500 mol / L, the dosage of molybdenum disulfide is 50-200 mg / L, and the dosage ratio of molybdenum disulfide to potassium permanganate is 1:(0.4-0.8).

[0009] The present invention also has the following technical features:

[0010] Specifically, the organic pollutants include phenol, chlorophenol, bisphenol A, carbamazepine, ciprofloxacin, sulfamethoxazole, diclofenac sodium, naproxen, ibuprofen, acetaminophen, caffeine, nitrobenzene, roxarsone, and para-aminobenzoic acid.

[0011] Furthermore, the concentration of the trace organic pollutants is 0.1–5 μM.

[0012] Furthermore, the particle size of the molybdenum disulfide powder is less than 2 μm.

[0013] Furthermore, the molybdenum disulfide powder can be added by dry addition or by wet addition in the form of a suspension.

[0014] Furthermore, the water includes one of the following: river water, lake water, reservoir water, groundwater, or wastewater or sewage containing trace amounts of organic pollutants discharged from domestic or industrial sources.

[0015] Compared with the prior art, the beneficial technical effects of this invention are:

[0016] (1) The method of the present invention uses molybdenum disulfide to activate potassium permanganate to degrade organic pollutants. The generated active Mn(III) has extremely high oxidation activity, which enhances the degradation ability of potassium permanganate. Compared with traditional potassium permanganate oxidation, due to the addition of the catalyst, not only is the removal rate of organic pollutants improved, but the dosage of potassium permanganate is also reduced, thus reducing the cost. It can also effectively alleviate the color problem caused by a high dosage of potassium permanganate.

[0017] (2) The molybdenum disulfide catalyst used in the method of the present invention is almost insoluble in water, and the dissolved trace amount of molybdenum is low in toxicity. After the catalytic process is completed, it can be separated from the water body by filtration or coagulation, and the impact on water quality is extremely low.

[0018] (3) The molybdenum disulfide catalyst used in this invention can be recovered and reused after the reaction, which reduces the application cost of the catalyst. The method of this invention has the advantages of simple process, easy operation, cheap and readily available chemical reagents, low operating cost, and easy implementation in the upgrading and transformation of existing water plants.

[0019] The specific content of the present invention will be further explained in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0020] Figure 1 This is a comparison chart of the removal rates of sulfamethoxazole in Example 1, Comparative Example 1, and Comparative Example 2.

[0021] Figure 2 This is a comparison chart of the removal rates of different organic pollutants for Example 2, Comparative Example 3, and Comparative Example 4;

[0022] Figure 3 This is a comparison chart of the removal rates of sulfamethoxazole by different dosages of potassium permanganate in Example 3;

[0023] Figure 4 This is a comparison chart of the removal rates of sulfamethoxazole by different dosages of molybdenum disulfide in Example 4;

[0024] Figure 5 This is a comparison chart of sulfamethoxazole removal rates under different pH conditions in Example 5;

[0025] Figure 6 This refers to the recycling of the molybdenum disulfide catalyst in Example 6;

[0026] Figure 7 This is a comparison chart of the removal rates of sulfamethoxazole by different metal sulfides in Example 7;

[0027] Figure 8 The graph shows the amount of molybdenum metal ions precipitated in the water and the removal by coagulation in Example 1. Detailed Implementation

[0028] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0029] Molybdenum disulfide (MoS2) is a transition metal sulfide with a two-dimensional layered structure similar to graphene. It consists of monolayers with strong covalent Mo-S bonds between them, and these atoms are tightly bonded together in the same plane. Due to its reducing properties, the Mo(Ⅳ) atoms in MoS2 readily lose electrons, transforming into higher valence states such as Mo(Ⅴ) or Mo(Ⅵ). It can be used as a catalyst in redox reactions. MoS2 also exhibits low toxicity and biocompatibility.

[0030] The technical concept of this invention is as follows: Molybdenum disulfide possesses a large specific surface area and total pore volume, good dispersibility, and can expose more catalytic active sites, resulting in a large contact area with the oxidant and high catalytic efficiency. Furthermore, the redox reaction between molybdenum disulfide and potassium permanganate generates an intermediate-valence active manganese species, Mn(III), which has a high redox potential (E0 = 1.54 V), thus possessing the ability to degrade numerous organic pollutants. This significantly enhances the ability of potassium permanganate to degrade organic pollutants, thereby activating potassium permanganate to degrade organic pollutants in water. This is also a characteristic that distinguishes the oxidation system provided by the method of this invention from existing advanced oxidation systems.

[0031] Sulfamethoxazole was selected as the target pollutant, and MoO2 was used as a catalyst to replace MoS2 in the activation of potassium permanganate. As the concentration of MoO2 increased from 50 mg / L to 2 g / L, the degradation rate of sulfamethoxazole remained at around 25%, while 50 mg / L of MoS2 could achieve a degradation rate of about 70% for sulfamethoxazole. This indicates that S, rather than Mo, plays a major role in the activation of potassium permanganate by molybdenum disulfide.

[0032] This invention discloses a method for degrading organic pollutants in water by activating potassium permanganate with molybdenum disulfide, comprising sequentially adding molybdenum disulfide powder and potassium permanganate to water containing trace amounts of organic pollutants, treating for 10 to 90 minutes, and after treatment, removing unreacted potassium permanganate and molybdenum disulfide powder by coagulation, sedimentation and filtration in sequence.

[0033] When the concentration of trace organic pollutants in the water is 0.1–5 μM, the dosage of potassium permanganate is 50–300 μmol / L, and the dosage of molybdenum disulfide is 25–150 mg / L.

[0034] When the concentration of trace organic pollutants in water is >5 μM, the dosage of potassium permanganate is 150-500 mol / L, the dosage of molybdenum disulfide is 50-200 mg / L, and the dosage ratio of molybdenum disulfide to potassium permanganate is 1:(0.4-0.8).

[0035] The organic pollutants mentioned include phenol, chlorophenol, bisphenol A, carbamazepine, ciprofloxacin, sulfamethoxazole, diclofenac sodium, naproxen, ibuprofen, acetaminophen, caffeine, nitrobenzene, roxarsone, and para-aminobenzoic acid, etc.

[0036] The concentration of the trace organic pollutants is 0.1–5 μM.

[0037] The particle size of the molybdenum disulfide powder is less than 2 μm.

[0038] The molybdenum disulfide powder can be added by dry addition or by wet addition after being prepared into a dispersion.

[0039] The water mentioned includes one of the following: river water, lake water, wastewater or sewage containing trace amounts of organic pollutants discharged from domestic or industrial sources.

[0040] The technical terms involved in this invention are explained as follows:

[0041] Dry dosing: refers to the direct addition of molybdenum disulfide powder into water through methods such as air spraying or stirring.

[0042] Wet dosing: Molybdenum disulfide is mixed with water to form a dispersion by means of ultrasound or other methods and then added into the water.

[0043] Example 1

[0044] The water containing organic pollutants used in this embodiment was prepared in the laboratory. Sulfamethoxazole, naproxen, diclofenac sodium, and nitrobenzene were selected as target pollutants. The concentrations of the four substances were determined by a high-performance liquid chromatograph U3000. The specific detection methods for each organic compound are shown in the table below.

[0045]

[0046] Molybdenum disulfide powder and potassium permanganate were added sequentially to water containing sulfamethoxazole. The mixture was treated with a magnetic stirrer at a stirring rate of 300 r / min for 60 min. After treatment, unreacted potassium permanganate and molybdenum disulfide powder were removed by coagulation, sedimentation and filtration. The initial concentration of sulfamethoxazole was 5 μM, the dosage of potassium permanganate was 200 μM and the dosage of molybdenum disulfide was 50 mg / L.

[0047] After adding the treated water into a sample bottle containing the quencher hydroxylamine hydrochloride, the residual concentration of pollutants was measured.

[0048] To ensure that molybdenum disulfide has the least impact on water quality, the amount of molybdenum dissolved in water after the reaction was also measured in this embodiment, and the remaining molybdenum was removed with a coagulant.

[0049] like Figure 8As shown, the residual [Mo] in the water after the reaction was measured to be 5.67 mg / L. After treatment with 30 mg / L of PAC coagulant and Fe2(SO4)3 coagulant, respectively, and after settling and filtration, the residual [Mo] in the water was measured to be 0.56 mg / L and 0.12 mg / L, respectively.

[0050] The results show that the metal ions dissolved from the catalyst can be effectively removed by coagulation, without causing more serious secondary pollution to the water body.

[0051] Comparative Example 1

[0052] The reaction conditions for this comparative example are the same as those for Example 1, except that potassium permanganate, an oxidant, is added only to water containing sulfamethoxazole.

[0053] Comparative Example 2

[0054] The reaction conditions for this comparative example are the same as those for Example 1, except that molybdenum disulfide is added only to water containing sulfamethoxazole.

[0055] As can be seen from Example 1 and Comparative Examples 1 and 2:

[0056] like Figure 1 As shown, the removal rate of sulfamethoxazole using potassium permanganate alone is approximately 4.7%; the removal rate of sulfamethoxazole using molybdenum disulfide alone is approximately 5%, while the removal rate of sulfamethoxazole in this embodiment is approximately 70%. This indicates that the potassium permanganate / molybdenum disulfide system can significantly improve the removal rate of sulfamethoxazole in water.

[0057] Example 2

[0058] In this embodiment, water containing organic pollutants sulfamethoxazole, naproxen, diclofenac sodium, and nitrobenzene was prepared, and the organic pollutants were removed according to the reaction conditions disclosed in Example 1.

[0059] The results are as follows Figure 2 As shown, in this embodiment, the removal rates of sulfamethoxazole, nitro, diclofenac sodium, and naproxen were 70%, 60%, 100%, and 32%, respectively.

[0060] Comparative Example 3

[0061] The reaction conditions for this comparative example are the same as those for Example 2, except that potassium permanganate, an oxidant, is added only to the water containing sulfamethoxazole.

[0062] like Figure 2 As shown, in this comparative example, the removal rates of sulfamethoxazole, nitro, diclofenac sodium and naproxen were 4.7%, 6.3%, 100% and 6%, respectively.

[0063] Comparative Example 4

[0064] The comparative example uses the same reaction conditions as Example 2, except that molybdenum disulfide is added to the water containing sulfamethoxazole.

[0065] like Figure 2 As shown, in this comparative example, the removal rates of sulfamethoxazole, nitro, diclofenac sodium, and naproxen were 5%, 3.5%, 6.2%, and 2.7%, respectively.

[0066] The conclusions drawn from Example 2 and Comparative Examples 3 and 4 are as follows:

[0067] Compared with potassium permanganate oxidation and molybdenum disulfide adsorption alone, the removal rates of sulfamethoxazole in water increased from 4.7% and 5% to 70% after potassium permanganate was activated with molybdenum disulfide, representing an increase of approximately 15 times; the removal rates of naproxen increased from 6.3% and 3.5% to 60%, representing increases of approximately 10 times and 17 times; the removal rates of diclofenac sodium increased from 100% and 6.2% to 100%, as potassium permanganate alone already achieved a 100% removal rate for diclofenac sodium, and the addition of the catalyst significantly improved its removal rate; the removal rates of nitrobenzene increased from 6% and 2.7% to 32%, representing increases of approximately 5.3 times and 12 times. This indicates that the potassium permanganate system significantly improves the removal rates of various organic pollutants in water.

[0068] Example 3

[0069] The reaction conditions in this embodiment are the same as in Example 1, except that the amount of potassium permanganate added is 100 μM, 200 μM, and 400 μM, ultimately yielding the following results. Figure 3 The graph shows a comparison of the removal rates of sulfamethoxazole by different dosages of potassium permanganate. Figure 3 It can be seen that the removal rate of sulfamethoxazole increases with the increase of potassium permanganate dosage.

[0070] Example 4

[0071] The reaction conditions in this embodiment are the same as in Example 1, except that the dosage of molybdenum disulfide is changed to 25, 50, 100, or 150 mg / L, respectively. The final result is as follows: Figure 4 The graph showing the removal rate of sulfamethoxazole by different dosages of molybdenum disulfide is as follows: Figure 4 It can be seen that the removal rate of sulfamethoxazole increases with the increase of molybdenum disulfide dosage.

[0072] Comparative Example 5

[0073] The reaction conditions for this comparative example are the same as those for Example 1, except that molybdenum disulfide is replaced with tungsten disulfide.

[0074] Comparative Example 6

[0075] The reaction conditions for this comparative example are the same as those for Example 1, except that molybdenum disulfide is replaced with ferrous sulfide.

[0076] Then, the products obtained in Example 1, Comparative Example 5, and Comparative Example 6 were added to water containing sulfamethoxazole at the same dosage, and the removal rate of sulfamethoxazole was tested to obtain the results shown below. Figure 7 The graph showing the removal rates of sulfamethoxazole by different metal sulfides is as follows: Figure 7 It can be seen that when molybdenum disulfide is added as a catalyst, the removal rate of sulfamethoxazole is significantly higher than that of other metal sulfides with the same dosage.

[0077] Example 5

[0078] To verify that the method of the present invention is applicable to a wide pH range, in this embodiment, molybdenum disulfide powder and potassium permanganate were sequentially added to 100 mL of water containing sulfamethoxazole at pH 3, 5, 7, 9, and 11, respectively, and treated for 60 min under magnetic stirring at 300 r / min. The initial concentration of sulfamethoxazole was 5 μM, the amount of potassium permanganate added was 200 μM, and the amount of molybdenum disulfide added was 50 mg / L.

[0079] like Figure 5 As shown, the potassium permanganate / molybdenum disulfide system exhibits excellent removal efficiency for sulfamethoxazole under pH conditions ranging from 3 to 9, indicating that the system is suitable for a wide pH range and possesses excellent oxidation efficiency.

[0080] Example 6

[0081] The water containing molybdenum disulfide, after being treated in Example 1, was centrifuged, washed, and dried to obtain a powder for the second reaction. The reaction process of Example 1 was repeated, and the centrifugation, washing, and drying process was repeated to obtain the catalyst for the third reaction. The catalyst for the fourth reaction was obtained in the same way.

[0082] like Figure 6 As shown, after the first reaction, and the second, third and fourth reactions, the catalytic efficiency of the catalyst gradually decreased. After the fourth use, the removal rate of sulfamethoxazole by the molybdenum disulfide-catalyzed potassium permanganate degradation was about 40%.

[0083] Compared to Comparative Example 1, the removal rate was still nearly 8 times higher, indicating that the catalytic performance of molybdenum disulfide remains. The reusability of the catalyst can effectively reduce application costs.

[0084] In summary, the method of this invention uses molybdenum disulfide to activate potassium permanganate to degrade organic pollutants. The generated active Mn(III) has extremely high oxidizing activity, which enhances the degradation ability of potassium permanganate. Compared with traditional potassium permanganate oxidation, the addition of the catalyst not only improves the removal rate of organic pollutants, but also reduces the dosage of potassium permanganate, thereby reducing costs. Furthermore, it can effectively alleviate the color problem caused by a higher dosage of potassium permanganate.

[0085] The above-described implementation process is merely an example to clearly illustrate this application and is not intended to limit the implementation methods. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all possible implementation methods here. However, obvious variations or modifications derived therefrom are still within the protection scope of this application.

Claims

1. A method for degrading organic pollutants in water using molybdenum disulfide-activated potassium permanganate, characterized in that, The process involves sequentially adding molybdenum disulfide powder and potassium permanganate to water containing trace amounts of organic pollutants, treating for 10-90 minutes, and then removing unreacted potassium permanganate and molybdenum disulfide powder by coagulation, sedimentation, and filtration after treatment. When the concentration of trace organic pollutants in the water is 0.1~5µM, the dosage of potassium permanganate is 50~300μmol / L and the dosage of molybdenum disulfide is 25~150 mg / L. When the concentration of trace organic pollutants in water is >5µM, the dosage of potassium permanganate is 150~500µM / L, the dosage of molybdenum disulfide is 50~200 mg / L, and the dosage ratio of molybdenum disulfide to potassium permanganate is 1:(0.4~0.8). The organic pollutants include sulfamethoxazole, diclofenac sodium, naproxen, and nitrobenzene.

2. The method for degrading organic pollutants in water by molybdenum disulfide-activated potassium permanganate as described in claim 1, characterized in that, The particle size of the molybdenum disulfide powder is less than 2µm.

3. The method for degrading organic pollutants in water by molybdenum disulfide-activated potassium permanganate as described in claim 1, characterized in that, The molybdenum disulfide powder can be added by dry addition or by wet addition after preparation into a suspension.

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