Method for removing organic pollutants using molybdenum dioxide promoted activated periodate

Abstract

The application discloses a method for removing organic pollutants by using molybdenum dioxide to promote activated periodate, and comprises the following steps: adding molybdenum dioxide, ferric salt and periodate into wastewater containing organic pollutants, and then performing catalytic degradation reaction to remove the organic pollutants in the wastewater. In the method, molybdenum dioxide is introduced into the homogeneous ferric / periodate system, and serves as an electron donor and mediator of a Fenton-like reaction. The molybdenum dioxide can not only accelerate the Fe 3+ / Fe 2+ cycle rate and promote the activation of the periodate, but also promote the generation of high-valence iron (Fe(IV)) in the system, form a non-radical pathway dominated oxidation mechanism, promote the degradation reaction to be more rapid and intense, and finally realize the efficient degradation of the organic pollutants. The method has the advantages of rapid degradation rate, good reusability, simple process, convenient operation and environmental friendliness, and can be widely used in the treatment of organic pollutant wastewater.

Description

Technical Field

[0001] This invention belongs to the field of organic pollutant water pollution treatment technology, specifically relating to a method for removing organic pollutants by using molybdenum dioxide to promote the activation of periodate. Background Technology

[0002] With rapid global industrialization, the emission of organic compounds has increased year by year. For example, antibiotics are widely used in human health, animal husbandry, and agriculture. Tetracycline, a common broad-spectrum antibiotic, is often directly released into the aquatic environment, posing a significant threat to human health and aquatic ecosystems. To date, various technologies have been used to remove and degrade organic pollutants in the aquatic environment, such as biodegradation, adsorption, and advanced oxidation processes (AOPs). AOPs technology is currently the mainstream method for treating toxic and recalcitrant organic pollutants worldwide, playing a crucial role in industrial wastewater treatment, municipal sewage treatment, and advanced drinking water treatment.

[0003] Periodate (PI, IO4) - As a novel solid oxidant, periodate is considered the most promising alternative to liquid oxidants. Under normal conditions, periodate alone is relatively stable and cannot oxidize organic pollutants (E0 = +1.60V / NHE). Therefore, various strategies have been developed to activate periodate and generate more reactive species, such as active iodine (IO3), including short-wave UV irradiation, alkaline treatment, freezing, transition metals, and carbon-based materials. · / IO4 · ), hydroxyl radicals (·OH), superoxide radicals (O2) ·- ) and singlet oxygen ( 1 O2), etc. Among all the methods studied, transition metal ions are considered one of the most promising periodate activators due to their low cost and excellent activation efficiency. Homogeneous Fe ions 2+ It is considered an excellent Fenton activator, Fe 2+ It has low toxicity, is ubiquitous in the environment, is inexpensive, and has high reactivity. Considering Fe... 2+ It is easily oxidized to Fe 3+ Fe 3+ Due to its high stability and the low storage and transportation costs of commercial iron salts, Fe has practical application value. 3+ and Fe 2+ The effective conversion between them becomes a key issue. However, the inventors of this application discovered in their previous research that Fe exists in the ferric sulfate / periodate system. 3+ / Fe 2+The defects of slow cycle, the need for strong acid reaction conditions, etc. make the system unable to efficiently remove organic pollutants in water. Therefore, how to obtain an effective activation method to accelerate the iron cycle rate in the ferric / high iodate system is of great significance to promote the activation of high iodate and ultimately achieve efficient degradation of organic pollutants. SUMMARY

[0004] The technical problem to be solved by the present application is to overcome the shortcomings of the prior art and provide a method for removing organic pollutants by using molybdenum dioxide to promote the activation of high iodate, which has fast degradation rate, good reusability, simple process, easy operation and environmental friendliness.

[0005] To solve the above technical problems, the following technical solutions are adopted in the present application.

[0006] A method for removing organic pollutants by using molybdenum dioxide to promote the activation of high iodate, comprising the following steps: adding molybdenum dioxide into wastewater containing organic pollutants, stirring, adding ferric salt and high iodate, and carrying out catalytic degradation reaction to remove organic pollutants in the wastewater.

[0007] The method is further improved, and the ratio of molybdenum dioxide to wastewater containing organic pollutants is 0.1g-0.8g:1L, the ratio of ferric salt to wastewater containing organic pollutants is 3mg-9mg:1L, and the ratio of high iodate to wastewater containing organic pollutants is 0.02mmol-0.26mmol:1L.

[0008] The method is further improved, and the ratio of molybdenum dioxide to wastewater containing organic pollutants is 0.6g-0.8g:1L, the ratio of ferric salt to wastewater containing organic pollutants is 7mg-9mg:1L, and the ratio of high iodate to wastewater containing organic pollutants is 0.05mmol-0.1mmol:1L.

[0009] The method is further improved, and the initial concentration of organic pollutants in the wastewater containing organic pollutants is ≤40mg / L.

[0010] The method is further improved, and the initial concentration of organic pollutants in the wastewater containing organic pollutants is 10mg / L-40mg / L.

[0011] The method is further improved, and the ferric salt is at least one of ferric sulfate, ferric nitrate and ferric chloride, the high iodate is sodium periodate, the organic pollutants in the wastewater containing organic pollutants are antibiotics, and the antibiotics are tetracycline.

[0012] The method is further improved, and the initial pH value of the wastewater containing organic pollutants is 2-10.

[0013] In a further improvement to the above method, the initial pH value of the wastewater containing organic pollutants is 2 to 7.

[0014] In a further improvement to the above method, the stirring time is 30 min to 60 min.

[0015] In a further improvement to the above method, the temperature of the catalytic degradation reaction is 5℃~35℃, and the time of the catalytic degradation reaction is 5min~15min.

[0016] Compared with the prior art, the advantages of the present invention are as follows:

[0017] This invention provides a method for removing organic pollutants by promoting the activation of periodate using molybdenum dioxide. Molybdenum dioxide, ferric salts, and periodate are added to wastewater containing organic pollutants to carry out a catalytic degradation reaction, thereby removing the organic pollutants from the wastewater. In this method, molybdenum dioxide is introduced into a homogeneous ferric / periodate system. It can act as an electron donor and mediator in a Fenton-like reaction. On one hand, a two-electron cycle is formed between Mo and Fe, causing the oxidation state of Mo to change from Mo(-II) to Mo(VI). This variable oxidation state gives Mo more active sites to achieve electron transfer; that is, Mo(IV) / Mo(VI) acts as an electron donor to transfer Fe... 3+ Rapidly reduced to Fe 2+ This accelerates the Fe in the system 3+ / Fe 2+ The circulation rate promotes the activation of periodate; on the other hand, molybdenum dioxide, as a mediator, can promote the generation of high-valent iron (Fe(IV)) in the system, forming an oxidation mechanism dominated by non-radical pathways, thereby making the degradation reaction faster and stronger, and ultimately achieving efficient degradation of organic pollutants. Taking tetracycline as an example, the method of this invention achieves a 100% degradation efficiency of tetracycline in 10 min, with a reaction rate constant of 0.3127 min. -1 ) is the ferric sulfate / periodate system (0.08489 min -1 3.68 times that of the molybdenum dioxide / ferric sulfate system (0.00691 min) -1 The degradation rate is 45.25 times that of the Fenton reaction. The method of this invention can broaden the effective pH range of Fenton-like reactions, and has advantages such as fast degradation rate, good reusability, simple process, convenient operation, and environmental friendliness. It can be widely used in the treatment of organic pollutant wastewater. Attached Figure Description

[0018] Figure 1 The graph shows the degradation effect of tetracycline on different reaction systems in Example 1 of this invention.

[0019] Figure 2The figure is the degradation effect of tetracycline by different reaction systems in Example 2 of the present application.

[0020] Figure 3 The figure is the degradation effect of tetracycline by different amounts of molybdenum dioxide in the molybdenum dioxide / iron sulfate / sodium periodate system in Example 3 of the present application.

[0021] Figure 4 The figure is the degradation effect of tetracycline by different amounts of iron sulfate in the molybdenum dioxide / iron sulfate / sodium periodate system in Example 4 of the present application.

[0022] Figure 5 The figure is the degradation effect of tetracycline by different amounts of sodium periodate in the molybdenum dioxide / iron sulfate / sodium periodate system in Example 5 of the present application.

[0023] Figure 6 The figure is the degradation effect of tetracycline by different initial pH values in the molybdenum dioxide / iron sulfate / sodium periodate system in Example 6 of the present application. DETAILED DESCRIPTION

[0024] The present application is further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the scope of protection of the present application is not limited thereby. The materials and instruments used in the following examples are commercially available.

[0025] Example 1:

[0026] A method for removing organic pollutants by using molybdenum dioxide to promote activated periodate, specifically a method for degrading and treating tetracycline-containing water bodies by using a molybdenum dioxide / iron sulfate / sodium periodate system, comprises the following steps:

[0027] 60 mg of molybdenum dioxide was weighed and added to 100 mL of a tetracycline solution with a concentration of 10 mg / L (the initial pH value of the solution was 3.8), and stirred at room temperature for 60 min to reach adsorption-desorption equilibrium; then, iron sulfate and sodium periodate (chemical formula: NaIO4, PI) were added in sequence, so that the concentrations of iron sulfate and sodium periodate in the system were 5 mg / L and 0.1 mM respectively, and the catalytic degradation reaction was carried out at 25°C for 10 min to complete the degradation of tetracycline in the water body.

[0028] Control group one (MoO2): no addition of iron sulfate and sodium periodate, and other conditions were the same.

[0029] Control group two (Fe 3+ ): no addition of molybdenum dioxide and sodium periodate, and other conditions were the same.

[0030] Control group three (PI): no addition of molybdenum dioxide and iron sulfate, and other conditions were the same.

[0031] Control group four (MoO2 / Fe 3+ ): without adding sodium periodate, other conditions are the same.

[0032] Control group five (MoO2 / PI): without adding iron sulfate, other conditions are the same.

[0033] Control group six (Fe 3+ / PI): without adding molybdenum dioxide, other conditions are the same.

[0034] In the catalytic degradation reaction, 1 mL of reaction solution was taken at a certain time interval (0 min, 2 min, 4 min, 6 min, 8 min, 10 min), filtered with a 0.22 μm filter head, and added to a liquid phase vial pre-added with 0.2 mL of 0.1 M sodium thiosulfate solution (chemical formula: NaS2O3), and the concentration of tetracycline in the solution was detected by liquid chromatography.

[0035] Figure 1 is the degradation effect of different reaction systems on tetracycline in Example 1 of the present application. It can be seen from Figure 1 that compared with the control group, the method of the present application significantly improves the degradation efficiency of tetracycline by the combination of molybdenum dioxide, iron sulfate and periodate, and the degradation efficiency of tetracycline reaches 100% at 10 min. In the iron sulfate / sodium periodate system (Fe 3+ / PI), the degradation efficiency of tetracycline is 61.8% at 10 min, which also shows that molybdenum dioxide can improve the performance of iron sulfate / periodate. In addition, the reaction rate constant of the molybdenum dioxide / iron sulfate / periodate system of the present application is 0.3127 min -1 , which is 3.68 times that of the iron sulfate / periodate system (0.08489 min -1 ) and 45.25 times that of the molybdenum dioxide / iron sulfate system (0.00691 min -1 ).

[0036] Example 2:

[0037] To investigate the promoting activation effect of molybdenum dioxide on different reaction systems, the molybdenum dioxide / iron sulfate / periodate system and the molybdenum dioxide / iron sulfate / hydrogen peroxide system were used to degrade tetracycline-containing water, including the following steps:

[0038] Take 2 parts of 10 mg of molybdenum dioxide, respectively, add 100 mL, 5 mg / L of tetracycline solution (the initial pH value of the solution is 3.8), stir at room temperature for 60 min, reach adsorption-desorption equilibrium; then, one part is added with iron sulfate and sodium periodate in turn, so that the concentration of iron sulfate and sodium periodate in the system is 5 mg / L and 0.1 mM respectively, and the other part is added with iron sulfate and hydrogen peroxide in turn, so that the concentration of iron sulfate and hydrogen peroxide in the system is 5 mg / L and 0.1 mM respectively, and the catalytic degradation reaction is carried out for 10 min, and the degradation of tetracycline in water body is completed.

[0039] In the catalytic degradation reaction, 1 mL of reaction solution was taken at a certain time interval (0 min, 2 min, 4 min, 6 min, 8 min, 10 min), filtered with a 0.22 μm filter head, and added to a liquid phase vial pre-added with 0.2 mL of 0.1 M sodium thiosulfate solution, and the concentration of tetracycline in the solution was detected by liquid chromatography.

[0040] Figure 2 The figure of the degradation effect of different reaction systems in Example 2 of the present application on tetracycline. From Figure 2 It can be seen that in the molybdenum dioxide / iron sulfate / hydrogen peroxide (MoO2 / Fe 3+ / H2O2) system, the degradation efficiency of tetracycline is 56% at 10 min; in the molybdenum dioxide / iron sulfate / sodium periodate (MoO2 / Fe 3+ / PI) system, the degradation efficiency of tetracycline is 100% at 10 min, it can be seen that the degradation rate of MoO2 / Fe 3+ / H2O2 system on tetracycline is significantly lower than that of MoO2 / Fe 3+ / PI system, because when molybdenum dioxide is added to hydrogen peroxide system, it does not have the function of inducing the generation of high valence iron (Fe(IV)) and selectively regulating the non-free radical path.

[0041] Example 3:

[0042] The effect of different amounts of molybdenum dioxide on the degradation of tetracycline was investigated, specifically using the molybdenum dioxide / iron sulfate / sodium periodate system to degrade tetracycline-containing water, including the following steps:

[0043] Take 10 mg, 20 mg, 40 mg, 60 mg, 80 mg of molybdenum dioxide, respectively, add to 100 mL, 5 mg / L of tetracycline solution (the initial pH value of the solution is 3.8), stir at room temperature for 60 min, reach adsorption-desorption equilibrium; then, add iron sulfate and sodium periodate in turn, so that the concentration of iron sulfate and sodium periodate in the system is 5 mg / L and 0.1 mM respectively, and the catalytic degradation reaction is carried out for 10 min, and the degradation of tetracycline in water body is completed.

[0044] In the catalytic degradation reaction, 1 mL of reaction solution was taken at certain time intervals (0 min, 2 min, 4 min, 6 min, 8 min, 10 min), filtered with a 0.22 μm filter, and added to a liquid chromatography vial containing 0.2 mL of 0.1 M sodium thiosulfate solution. The concentration of tetracycline in the solution was detected by liquid chromatography.

[0045] Figure 3 This is a graph showing the degradation effect of the molybdenum dioxide / ferric sulfate / sodium periodate system on tetracycline under different molybdenum dioxide addition amounts in Example 3 of the present invention. From... Figure 3 The results show that when the molybdenum dioxide dosage increased from 0.1 g / L to 0.8 g / L, the degradation efficiency of tetracycline increased from 77.5% to 100%, and the k value also increased. This indicates that increasing the molybdenum dioxide dosage not only improved the degradation efficiency of tetracycline but also accelerated the removal rate of the reaction. Furthermore, when the molybdenum dioxide dosage exceeded 0.6 g / L, the effect of increasing the dosage on tetracycline degradation was limited.

[0046] Example 4:

[0047] The effect of different ferric sulfate dosages on tetracycline degradation was investigated. Specifically, a molybdenum dioxide / ferric sulfate / sodium periodate system was used to treat tetracycline-containing water, including the following steps:

[0048] Five 60mg portions of molybdenum dioxide were weighed and added to 100mL and 5mg / L tetracycline solutions respectively (the initial pH of the solution was 3.8). The solutions were stirred at room temperature for 60min to reach adsorption-desorption equilibrium. Then, ferric sulfate and sodium periodate were added sequentially to make the concentrations of ferric sulfate in the system 1mg / L, 3mg / L, 5mg / L, 7mg / L, and 9mg / L, respectively, and the concentration of sodium periodate in the system 0.1mM. The catalytic degradation reaction was carried out for 10min to complete the degradation of tetracycline in the water.

[0049] In the catalytic degradation reaction, 1 mL of reaction solution was taken at certain time intervals (0 min, 2 min, 4 min, 6 min, 8 min, 10 min), filtered with a 0.22 μm filter, and added to a liquid chromatography vial containing 0.2 mL of 0.1 M sodium thiosulfate solution. The concentration of tetracycline in the solution was detected by liquid chromatography.

[0050] Figure 4 This is a graph showing the degradation effect of the molybdenum dioxide / ferric sulfate / sodium periodate system on tetracycline under different amounts of ferric sulfate added in Example 4 of the present invention. From... Figure 4As can be seen from Table 1, after 4 minutes of catalytic degradation reaction, the degradation efficiencies of tetracycline are 28.8%, 48.8%, 69.9%, 93.5% and 100% when the concentrations of ferric sulfate are 1 mg / L, 3 mg / L, 5 mg / L, 7 mg / L and 9 mg / L respectively; meanwhile, the corresponding degradation rates increase from 0.07129 min -1 to 1.18378 min -1 , which may be due to that low initial Fe 3+ content limits the generation of Fe 2+ , and Fe 2+ is an effective activator of periodate to generate free radicals.

[0051] Example 5:

[0052] The effect of different amounts of added sodium periodate on the degradation of tetracycline was investigated, and the degradation of tetracycline in water by the molybdenum dioxide / ferric sulfate / sodium periodate system was carried out, including the following steps:

[0053] 4 portions of 60 mg of molybdenum dioxide were weighed and added to 100 mL of a tetracycline solution with a concentration of 5 mg / L (the initial pH value of the solution was 3.8), and stirred at room temperature for 60 min to reach adsorption-desorption equilibrium; then, ferric sulfate and sodium periodate were added in sequence, so that the concentration of ferric sulfate in the system was 5 mg / L, and the concentration of sodium periodate in the system was 0.02 mM, 0.1 mM, 0.18 mM and 0.26 mM respectively, and the catalytic degradation reaction was carried out for 10 min to complete the degradation of tetracycline in the water.

[0054] In the catalytic degradation reaction, 1 mL of reaction solution was taken at certain time intervals (0 min, 2 min, 4 min, 6 min, 8 min, 10 min), filtered with a 0.22 μm filter head, and added to a liquid phase vial to which 0.2 mL of a sodium thiosulfate solution with a concentration of 0.1 M had been added in advance, and the concentration of tetracycline in the solution was detected by liquid chromatography.

[0055] Figure 5 Figure 1 is a diagram of the degradation effect of the molybdenum dioxide / ferric sulfate / sodium periodate system on tetracycline at different amounts of added sodium periodate in Example 5 of the present application. As can be seen from Figure 1, Figure 5 when the dosage of sodium periodate increases from 0.02 mM to 0.1 mM, the degradation efficiency of tetracycline increases significantly; meanwhile, the k value increases from 0.11015 min -1 to 0.3127 min -1 , indicating that the increase of the dosage of sodium periodate promotes the generation of IO4 -and active site. In addition, the excess of periodate (>0.1 mM) has a significant inhibitory effect, when the amount of periodate reaches 0.26 mM, the removal rate of tetracycline is only 61.8%, the reason may be that IO4 - can compete with tetracycline free radicals. In summary, the molybdenum dioxide / iron sulfate / periodate system has a high utilization rate, and 0.1 mM of sodium periodate is sufficient to effectively degrade tetracycline. -

[0056] Example 6:

[0057] The effect of different initial pH values on tetracycline degradation was investigated, specifically using the molybdenum dioxide / iron sulfate / periodate system to degrade tetracycline-containing water, including the following steps:

[0058] Six 60 mg of molybdenum dioxide were weighed and added to 100 mL of 5 mg / L tetracycline solution, one of which was not adjusted in pH, with an initial pH of 3.8, and the other five were adjusted to pH values of 2.95, 4.92, 7.09, 9.04 and 11.01 using 0.1 mol / L hydrochloric acid and sodium hydroxide solution, respectively. Stirring at room temperature for 60 min to reach adsorption-desorption equilibrium; then, iron sulfate and sodium periodate were added in turn, so that the concentrations of iron sulfate and sodium periodate in the system were 5 mg / L and 0.1 mM, respectively, and the catalytic degradation reaction was carried out for 10 min to complete the degradation of tetracycline in the water body.

[0059] In the catalytic degradation reaction, 1 mL of reaction solution was taken at certain time intervals (0 min, 2 min, 4 min, 6 min, 8 min, 10 min), filtered with a 0.22 μm filter, and added to a liquid phase vial pre-added with 0.2 mL of 0.1 M sodium thiosulfate solution, and the concentration of tetracycline in the solution was detected by liquid chromatography.

[0060] Figure 6 The figure shows the degradation effect of the molybdenum dioxide / iron sulfate / periodate system on tetracycline at different initial pH values in Example 6 of the present application. Figure 6 In the figure, the "control" curve represents the degradation of tetracycline at an initial pH of 3.8. As shown in Figure 6 The removal rate of tetracycline in the molybdenum dioxide / iron sulfate / periodate system has a significant correlation with the pH value of the solution, and the removal rate of tetracycline decreases with the increase of the pH value. In the pH range of 2.95-9.04, the degradation efficiency of the molybdenum dioxide / iron sulfate / periodate system on tetracycline is between 79.29% and 100%. However, when the pH value rises to 11 (strong alkaline conditions), the degradation efficiency and k value decrease sharply to 30% and 0.03077 min​-1 This can be due to Fe 3+ Precipitation leads to Fe 2+ It is difficult to regenerate. The results show that the molybdenum dioxide / ferrous sulfate / peroxydisulfate system constructed by the application maintains good activity under acidic and near-neutral conditions as a Fenton-like system.

[0061] To sum up, the method for removing organic pollutants by using molybdenum dioxide to promote activated peroxydisulfate has the advantages of fast degradation rate, good reusability, simple process, easy operation, environmental friendliness, etc., can be widely applied to the treatment of organic pollutant wastewater, and can realize efficient removal of organic pollutants, and has good application prospect.

[0062] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Although the present application has been disclosed as above with a preferred embodiment, it is not intended to limit the present application. Any person skilled in the art can make many possible changes and modifications to the technical solutions of the present application, or modify equivalent embodiments with equivalent changes, without departing from the spirit and technical solutions of the present application. Therefore, any simple modification, equivalent replacement, equivalent change and modification of the above embodiments according to the technical essence of the present application, which does not deviate from the technical solutions of the present application, still belongs to the protection scope of the technical solutions of the present application.

Claims

1. A method for removing organic pollutants using activated periodate promoted by molybdenum dioxide, characterized by, The method comprises the following steps: The method comprises the following steps:

2. The method for removing organic pollutants using activated periodate promoted by molybdenum dioxide according to claim 1, characterized in that, The method comprises the following steps:

3. The method for removing organic pollutants using activated periodate promoted by molybdenum dioxide according to claim 2, characterized in that, The initial concentration of the organic pollutants in the wastewater containing organic pollutants is ≤40 mg / L.

4. The method for removing organic pollutants using activated periodate promoted by molybdenum dioxide according to any one of claims 1 to 3, characterized in that, The initial concentration of the organic pollutants in the wastewater containing organic pollutants is 10 mg / L-40 mg / L.

5. The method for removing organic contaminants using activated periodate promoted by molybdenum dioxide according to any one of claims 1 to 3, characterized in that, The trivalent iron salt is at least one of ferric sulfate, ferric nitrate and ferric chloride, the periodate is sodium periodate, the organic pollutants in the wastewater containing organic pollutants are antibiotics, and the antibiotics are tetracycline.

6. The method for removing organic pollutants using activated periodate promoted by molybdenum dioxide according to claim 5, characterized in that, The initial pH value of the wastewater containing organic pollutants is 2-10.

7. The method for removing organic contaminants using activated periodate promoted by molybdenum dioxide according to any one of claims 1 to 3, characterized in that, The initial pH value of the wastewater containing organic pollutants is 2-7.

8. The method for removing organic contaminants using activated periodate promoted by molybdenum dioxide according to any one of claims 1 to 3, characterized in that, The stirring time is 30 min-60 min. The temperature of the catalytic degradation reaction is 5°C-35°C, and the time of the catalytic degradation reaction is 5 min-15 min.

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