A method for treating wastewater by activating peracetic acid with molybdenum carbide

Abstract

This invention provides a method for treating wastewater using molybdenum carbide-activated peracetic acid, relating to the field of advanced oxidation water treatment. The method includes the following steps: mixing organic wastewater and peracetic acid in a reactor, adjusting the pH, and then adding molybdenum carbide to initiate the oxidation reaction, rapidly degrading pollutants in the water. The pH of the organic wastewater is preferably weakly alkaline. In this invention, organic pollutants can be oxidized and degraded by active species generated by molybdenum carbide-activated peracetic acid, such as organic free radicals and hydroxyl free radicals. The degradation efficiency of sulfamethoxazole in the organic wastewater is highest at an initial pH of 9, achieving a removal rate of over 95% for different concentrations of sulfamethoxazole within two minutes. It also has a certain removal effect on other organic pollutants such as methylene blue. Molybdenum carbide is a solid powder, making it easily removed from water. This invention requires no additional energy intake, and peracetic acid also disinfects and sterilizes the water.

Description

Technical Field

[0001] This invention relates to the field of advanced oxidation water treatment, specifically to a method for treating wastewater by molybdenum carbide-activated peracetic acid. Background Technology

[0002] Due to improper wastewater discharge and waste treatment, many aquatic environments have been polluted by anthropogenic organic compounds, making the presence of organic pollutants a serious problem in water treatment. Many organic pollutants are biotoxic and have carcinogenic, teratogenic, and mutagenic effects, while traditional water treatment processes are ineffective in removing some emerging micropollutants. Therefore, developing more effective methods to degrade organic pollutants in water bodies is of great significance for the protection of the aquatic environment.

[0003] Among various water treatment methods, advanced oxidation processes (AOS) have gained widespread recognition for their ability to degrade emerging pollutants in water. AOS relies on the breaking of peroxide bonds in peroxides to generate free radicals with strong oxidizing power, demonstrating its superior ability to remove stubborn pollutants from water. Currently, hydroxyl radical-based AOS is a widely studied treatment method, as hydroxyl radicals possess high redox potentials and can degrade various pollutants non-selectively. However, the efficiency of hydroxyl radical-based AOS is significantly affected by pH, primarily operating under acidic conditions. Furthermore, the transportation and storage conditions of hydrogen peroxide, the mainstream oxidant for generating hydroxyl radicals, are quite stringent. These drawbacks severely limit the application of hydroxyl radical-based AOS processes. Therefore, the search for more efficient, safer, and widely applicable oxidants is receiving increasing attention.

[0004] Peracetic acid, as an alternative oxidant and disinfectant for wastewater treatment, has attracted widespread attention due to its high redox potential and low disinfection byproducts. Peracetic acid is a product obtained from the reaction of hydrogen peroxide and acetic acid under acidic conditions. It contains peroxy bonds similar to those in hydrogen peroxide, thus serving as a precursor for free radicals. It supplies free radical generation by breaking its peroxy bonds through electron transfer mechanisms or energy intake. Furthermore, the peroxy bond energy of peracetic acid is lower than that of hydrogen peroxide, meaning it is more easily activated and thus generates more reactive free radicals. The main reactive species generated by activated peracetic acid are organic free radicals. Organic free radicals have a longer half-life than hydroxyl radicals, therefore exhibiting a more stable mass transfer process and better contact with target compounds. Compared to some traditional disinfectants, peracetic acid offers advantages in water disinfection and microbial inactivation, including: high oxidizing power, low pH dependence, simple implementation, synergistic effects in degrading organic pollutants and inactivating pathogens in water, and no secondary pollution. Therefore, peracetic acid has become a promising and environmentally friendly water treatment disinfectant.

[0005] There are various methods for activating peracetic acid, including electrical, thermal, external radiation energy (such as ultraviolet light and ultrasound), transition metal ions, transition metal oxides, transition metal sulfides, zero-valent copper, and activated carbon fibers. While methods such as light irradiation, heating, and ultrasound do not produce toxic byproducts, they require additional energy input. Activated carbon fibers, although not requiring additional energy, have lower activation efficiency for peracetic acid. Currently, transition metal catalysts are widely used to activate oxidants to generate active free radicals, requiring no additional energy and exhibiting high activation efficiency for peracetic acid.

[0006] Generally, transition metal catalysts can be divided into homogeneous catalysts and heterogeneous catalysts. Because homogeneous catalysts dissolve in water and are difficult to remove from water bodies, the concentration of metal ions in the water increases, causing secondary pollution. Therefore, researchers have turned their attention to heterogeneous catalysts. Heterogeneous catalysts have advantages such as a wide pH range, low precipitation rate, high activation efficiency for peracetic acid, and easy removal from water bodies. However, heterogeneous metal catalysts inevitably leach metal ions into the treated water, posing potential environmental risks. For example, cobalt-based catalysts leach toxic and carcinogenic cobalt ions, while excessive copper ions leached by copper-based catalysts can hinder biological development and plant nutrient absorption. Therefore, there is an urgent need to develop new methods for activating peracetic acid to more effectively degrade pollutants in water. Summary of the Invention

[0007] In light of the above background, and to address the problems of low efficiency, narrow pH range, and high energy consumption and secondary pollution associated with traditional biochemical methods for treating organic wastewater, as well as the challenges of peracetic acid activation, this invention aims to provide a method for degrading pollutants in water using molybdenum carbide-activated peracetic acid. This method rapidly generates highly reactive free radicals such as organic free radicals and hydroxyl free radicals from peracetic acid, effectively degrading pollutants in wastewater under weakly alkaline conditions. This invention improves the pollutant removal capacity of advanced oxidation processes, reduces energy consumption and environmental pollution, and also disinfects the water, making it an effective and environmentally friendly method for treating organic wastewater.

[0008] In order to achieve the above objectives, the present invention adopts the following technical solutions:

[0009] A method for treating wastewater by molybdenum carbide-activated peracetic acid includes the following steps: adding peracetic acid solution to the wastewater, adjusting the pH, adding molybdenum carbide and stirring to react, thereby degrading pollutants in the wastewater.

[0010] Preferably, the molar concentration ratio between the peracetic acid solution and molybdenum carbide is (0.13–1.41):1.

[0011] Preferably, the initial pH value of the reaction is 3 to 11, and the reaction time is 1 to 10 min.

[0012] Preferably, the initial pH of the reaction is 7-9, and the reaction time is 2-3 minutes.

[0013] Preferably, the dosage of peracetic acid solution in 100 mL of wastewater is 20–100 μL, and the concentration of peracetic acid solution is 10–20 wt%.

[0014] Preferably, the dosage of peracetic acid solution in 100 mL of wastewater is 60–80 μL, and the concentration of peracetic acid solution is 15–20 wt%.

[0015] Preferably, the molar concentration ratio between peracetic acid and coexisting hydrogen peroxide in the peracetic acid solution is 0.35 to 0.40:1.

[0016] Preferably, the concentration of the pollutant is 2–10 mg / L.

[0017] Preferred contaminants include sulfamethoxazole, naproxen, methylene blue, and rhodamine B.

[0018] Preferably, the dosage of molybdenum carbide in the wastewater is 0.2–1.0 g / L.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] In the method for treating wastewater by molybdenum carbide-activated peracetic acid provided by this invention, molybdenum carbide can effectively activate peracetic acid. Organic pollutants are directly oxidized by peracetic acid or degraded by reactive species such as hydroxyl radicals, acetoxy radicals, and acetylperoxy radicals generated by its activation. The effect is better under weakly alkaline conditions (pH=7-9), and solid molybdenum carbide is also easily removed from water. This invention can achieve a removal rate of over 95% for different concentrations of sulfamethoxazole within two minutes, and also has a certain removal effect on other pollutants such as methylene blue. This invention does not require additional energy intake, and can disinfect and sterilize water while removing organic pollutants. This invention does not produce persistent toxic or mutagenic residues or byproducts, does not generate secondary pollution, has mild reaction conditions, and is simple to operate. Attached Figure Description

[0021] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention, wherein:

[0022] Figure 1 The graphs show the degradation effects of sulfamethoxazole in the single peracetic acid system, the single molybdenum carbide system, the molybdenum carbide activated hydrogen peroxide system, and the molybdenum carbide activated peracetic acid system in Comparative Examples 1-3 and Example 1.

[0023] Figure 2This is a graph showing the effect of different peracetic acid dosages on the degradation of sulfamethoxazole in the molybdenum carbide-activated peracetic acid system of Example 2.

[0024] Figure 3 This is a graph showing the effect of different molybdenum carbide dosages on the degradation of sulfamethoxazole in the molybdenum carbide-activated peracetic acid system in Example 3.

[0025] Figure 4 This is a graph showing the effect of different initial pH values ​​on the degradation of sulfamethoxazole in the molybdenum carbide-activated peracetic acid system in Example 4.

[0026] Figure 5 This is a graph showing the effect of different concentrations of sulfamethoxazole on the degradation of the molybdenum carbide-activated peracetic acid system in Example 5.

[0027] Figure 6 The graph shows the effect of the molybdenum carbide-activated peracetic acid system in Example 6 on the degradation of sulfamethoxazole, naproxen, methylene blue, and rhodamine B. Detailed Implementation

[0028] The following disclosure provides many different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed.

[0029] This invention provides a method for treating organic wastewater using a molybdenum carbide-activated peracetic acid system, comprising the following steps:

[0030] Organic wastewater and peracetic acid were mixed in a chemical reactor, the pH of the solution was adjusted, and molybdenum carbide was added to start the catalytic oxidation reaction. The initial pH of the reaction was 3 to 11, and the molar concentration ratio between peracetic acid solution and molybdenum carbide was (0.13 to 1.41):1.

[0031] In this invention, unless otherwise specified, all material components are commercially available products well known to those skilled in the art.

[0032] In this invention, the initial pH of the reaction is preferably 7 to 9. When the initial pH of the reaction itself is not between 7 and 9, it is preferable to adjust the pH of the reaction to the above range. This invention does not have any particular limitation on the pH adjusting agent used for pH adjustment, such as sulfuric acid solution or sodium hydroxide solution.

[0033] In this invention, the organic pollutants in the organic wastewater include any one of sulfamethoxazole, naproxen, methylene blue, and rhodamine B, with sulfamethoxazole being the primary target pollutant. The preferred concentration of organic pollutants in the organic wastewater is 2–10 mg / L.

[0034] In this invention, peracetic acid is added in the form of an aqueous peracetic acid solution, wherein the ratio of peracetic acid to coexisting hydrogen peroxide in the aqueous peracetic acid solution is 0.35 to 0.40:1 (molar concentration ratio).

[0035] In this invention, the concentration of the peracetic acid aqueous solution is preferably 10-20 wt%, more preferably 15-20 wt%, and even more preferably 16-18 wt%.

[0036] In this invention, the amount of peracetic acid added to 100 mL of wastewater is preferably 20–100 μL, and more preferably 60–80 μL.

[0037] In this invention, peracetic acid can be activated by molybdenum carbide under conditions of pH 7 to 9, and transformed into hydroxyl radicals, acetoxy radicals, and acetylperoxy radicals.

[0038] In this invention, the activating catalyst is any one of α-molybdenum carbide, β-molybdenum carbide and η-molybdenum carbide, and molybdenum carbide is added directly to the mixed solution of organic wastewater and peracetic acid in solid powder form.

[0039] In this invention, the dosage of molybdenum carbide is preferably 0.2 to 1.0 g / L, and more preferably 0.8 to 1.0 g / L.

[0040] In this invention, the catalytic oxidation reaction is preferably carried out at room temperature and atmospheric pressure.

[0041] In this invention, the catalytic oxidation reaction time is preferably 1 to 10 min, and more preferably 2 to 3 min.

[0042] The method for treating organic wastewater provided by this invention has mild reaction conditions.

[0043] In the method for treating organic wastewater using a molybdenum carbide-activated peracetic acid system provided by this invention, organic pollutants are degraded by the oxidation of reactive oxygen groups such as hydroxyl radicals, acetoxy radicals, and acetylperoxy radicals generated by the molybdenum carbide-activated peracetic acid. Compared with H2O2, the peracetic acid used in this invention can generate more strong oxidizing free radicals under weakly alkaline conditions, resulting in higher degradation efficiency for organic pollutants. Furthermore, peracetic acid can simultaneously disinfect and sterilize without producing secondary pollution. The method provided by this invention is suitable for treating weakly alkaline organic wastewater, with mild reaction conditions, simple operation, no need for additional energy intake, and strong practical application capabilities. It has broad application prospects for the degradation and removal of pollutants in water.

[0044] The technical solutions of this invention will now be clearly and completely described in conjunction with the embodiments thereof. Obviously, the described embodiments are merely some, not all, of the embodiments of this invention. The invention will be described in detail below with reference to the embodiments and accompanying drawings, but this should not be construed as limiting the scope of protection of this invention.

[0045] Comparative Example 1 - "Peracetic Acid" System

[0046] At room temperature, prepare 100 ml of 10 mg / L sulfamethoxazole aqueous solution, add 60 μL of 16–18 wt% peracetic acid, adjust the initial pH of the solution to 9, stir for 120 s, and take 2 mL samples every 30 s during the reaction to detect the concentration of pollutants.

[0047] Comparative Example 2 - "Molybdenum Carbide" System

[0048] At room temperature, prepare 100 ml of 10 mg / L sulfamethoxazole aqueous solution, adjust the initial pH of the solution to 9, add 0.08 g of molybdenum carbide powder to start the reaction, stir for 120 s, and take 2 mL samples every 30 s during the reaction to detect the concentration of pollutants.

[0049] Comparative Example 3 - "Molybdenum Carbide Activated Hydrogen Peroxide" System

[0050] At room temperature, prepare 100 ml of 10 mg / L sulfamethoxazole aqueous solution, add 40 μL of 30% hydrogen peroxide to adjust the initial pH of the solution to 9, add 0.08 g of molybdenum carbide powder to start the reaction, stir for 120 s, and take 2 mL samples every 30 s during the reaction to detect the concentration of pollutants.

[0051] Example 1 - "Molybdenum carbide activated peracetic acid" system

[0052] At room temperature, prepare 100 ml of 10 mg / L sulfamethoxazole aqueous solution, add 60 μL of 16–18 wt% peracetic acid, adjust the initial pH of the solution to 9, add 0.08 g of molybdenum carbide powder (the molybdenum carbide in the examples is selected from any one of α-molybdenum carbide, β-molybdenum carbide and η-molybdenum carbide) to start the reaction, stir for 120 s, and take 2 mL samples every 30 s during the reaction to detect the concentration of pollutants.

[0053] The results of Comparative Examples 1-3 and Example 1 are shown in Figure 1 The degradation effects of the pollutants on the "peracetic acid" system (Comparative Example 1), the "molybdenum carbide" system (Comparative Example 2), the "molybdenum carbide-activated peracetic acid" system (Example 1), and the "molybdenum carbide-activated hydrogen peroxide" system (Comparative Example 3) are shown in curves 1, 2, 4, and 3, respectively. After 120 s of reaction, the removal rate of sulfamethoxazole in the "peracetic acid" system was only 1.5%; in the "molybdenum carbide" system, the removal rate was 4.0%; in the "molybdenum carbide-activated hydrogen peroxide" system, the removal rate was 6.6%; while in the "molybdenum carbide-activated peracetic acid" system, the removal rate of sulfamethoxazole increased to 96.1%.

[0054] Therefore, compared with the molybdenum carbide system, the peracetic acid system, and the molybdenum carbide-activated hydrogen peroxide system, the molybdenum carbide-activated peracetic acid system has a significant degradation effect on sulfamethoxazole, indicating that molybdenum carbide can efficiently activate peracetic acid, thereby rapidly degrading sulfamethoxazole, and that hydrogen peroxide, which coexists with peracetic acid, contributes very little to the degradation process of pollutants.

[0055] Example 2

[0056] Under ambient temperature conditions, with a molybdenum carbide dosage of 0.8 g / L and a pH of 9, 20 μL, 40 μL, 60 μL, 80 μL, and 100 μL of peracetic acid solution (concentration of 16–18 wt%) were added to 100 mL of sulfamethoxazole organic wastewater with a concentration of 10 mg / L for reaction. The results are shown below. Figure 2 .

[0057] When the peracetic acid dosage was 20 μL, 40 μL, 60 μL, 80 μL and 100 μL, the corresponding curves were 5, 6, 7, 8 and 9, respectively. After 120 s of reaction, the removal rates of sulfamethoxazole were 44.3%, 61.5%, 96.1%, 90.1% and 64.5%, respectively.

[0058] Therefore, in the molybdenum carbide-activated peracetic acid system, when the molybdenum carbide dosage is 0.8 g / L, the peracetic acid dosage is 60 μL / 100 mL, which has the best removal effect on sulfamethoxazole.

[0059] Example 3

[0060] Under normal temperature conditions, with peracetic acid concentration of 16–18 wt% added at a dosage of 60 μL / 100 mL, and the pH of the wastewater adjusted to 9, 0.02 g, 0.04 g, 0.06 g, 0.08 g, and 0.1 g of molybdenum carbide were added to 100 mL of sulfamethoxazole organic wastewater with a concentration of 10 mg / L, respectively, for reaction. The results are shown in […]. Figure 3 .

[0061] When the molybdenum carbide dosage was 0.02 g, 0.04 g, 0.06 g, 0.08 g, and 0.1 g, the corresponding curves were 10, 11, 12, 13, and 14, respectively. After 120 s of reaction, the removal rates of sulfamethoxazole were 42.0%, 51.2%, 73.6%, 96.1%, and 93.4%, respectively.

[0062] Therefore, in the molybdenum carbide-activated peracetic acid system, with a peracetic acid dosage of 60 μL / 100 mL and an initial reaction pH of 9, the molybdenum carbide dosage of 0.8 g / L showed the best removal effect for sulfamethoxazole.

[0063] Example 4

[0064] Under ambient temperature conditions, a peracetic acid system was activated using molybdenum carbide. 60 μL of 16–18 wt% peracetic acid was added to 100 mL of a 10 mg / L sulfamethoxazole solution, and the initial pH of the solution was adjusted to 3, 5, 7, 9, and 11. Subsequently, 0.08 g of molybdenum carbide was added to initiate the reaction. Results are shown below. Figure 4 .

[0065] Results analysis showed that initial pH values ​​of 3, 5, 7, 9, and 11 corresponded to curves 15, 16, 17, 18, and 19, respectively. After 120 seconds of reaction, the removal rates of sulfamethoxazole were 5.6%, 23.1%, 60.4%, 96.1%, and 18.8%, respectively.

[0066] Therefore, in the molybdenum carbide-activated peracetic acid system, when the added peracetic acid dosage is 60 μL / 100 mL and the molybdenum carbide dosage is 0.8 g / L, the removal effect of sulfamethoxazole is best when the initial pH value of the reaction is 9.

[0067] Example 5

[0068] Under ambient temperature conditions, a peracetic acid system was activated with molybdenum carbide. The concentrations of sulfamethoxazole in 100 mL of organic wastewater were adjusted to 2 mg / L, 5 mg / L, and 10 mg / L under the following conditions: peracetic acid concentration of 16–18 wt% (60 μL / 100 mL), molybdenum carbide dosage of 0.8 g / L, and initial pH of 9. Results are shown below. Figure 5 .

[0069] When the concentration of sulfamethoxazole in 100 mL of organic wastewater was 2 mg / L, 5 mg / L, and 10 mg / L, the corresponding curves were 20, 21, and 22, respectively. After 120 s of reaction, the removal rates of sulfamethoxazole were 99.0%, 98.0%, and 96.1%, respectively.

[0070] Therefore, in the molybdenum carbide-activated peracetic acid system, under the conditions of peracetic acid dosage of 60 μL / 100 mL, molybdenum carbide dosage of 0.8 g / L, and initial pH of 9, it has a good removal effect on different concentrations of sulfamethoxazole.

[0071] Example 6

[0072] Under ambient temperature conditions, a peracetic acid system was activated with molybdenum carbide. The reaction was carried out with 100 mL of 10 mg / L sulfamethoxazole solution, naproxen solution, methylene blue solution, and rhodamine B solution, respectively, at a peracetic acid concentration of 16–18 wt% and a dosage of 60 μL / 100 mL, a molybdenum carbide dosage of 0.8 g / L, and an initial pH of 9. The results are shown below. Figure 6 .

[0073] In the molybdenum carbide-activated peracetic acid system, when the organic wastewater consisted of 100 mL of sulfamethoxazole solution, naproxen solution, methylene blue solution, and rhodamine B solution with a concentration of 10 mg / L, the removal rates of sulfamethoxazole, naproxen, methylene blue, and rhodamine B after 120 s of reaction were 96.1%, 69.4%, 87.2%, and 44.5%, respectively.

[0074] Therefore, in the molybdenum carbide-activated peracetic acid system, under the conditions of peracetic acid dosage of 60 μL / 100 mL, molybdenum carbide dosage of 0.8 g / L, and initial solution pH of 9, different types of pollutants can be removed. Among them, the removal effect on sulfamethoxazole is the best, and the removal effects on methylene blue, naproxen, and rhodamine B decrease in that order.

[0075] In summary, compared to peracetic acid or molybdenum carbide treatment methods alone, the molybdenum carbide-activated peracetic acid system method for treating organic wastewater provided by this invention exhibits good degradation effects on various organic pollutants such as sulfamethoxazole, naproxen, methylene blue, and rhodamine B. Furthermore, the method provided by this invention is more suitable for treating weakly alkaline organic wastewater.

[0076] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the claims.

[0077] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A method for treating wastewater using molybdenum carbide-activated peracetic acid, characterized in that, The following steps are involved: Peracetic acid solution was added to the wastewater, the pH was adjusted, and then molybdenum carbide was added and stirred to react and degrade the pollutants in the wastewater. The initial pH value of the reaction is 7-9, and the reaction time is 2-3 minutes.

2. The method for treating wastewater by molybdenum carbide-activated peracetic acid according to claim 1, characterized in that, The molar concentration ratio between the peracetic acid solution and the molybdenum carbide is (0.13–1.41):

1.

3. The method for treating wastewater by molybdenum carbide-activated peracetic acid according to claim 1, characterized in that, In 100 mL of the wastewater, the dosage of the peracetic acid solution is 20–100 μL, and the concentration of the peracetic acid solution is 10–20 wt%.

4. The method for treating wastewater by molybdenum carbide-activated peracetic acid according to claim 3, characterized in that, In 100 mL of the wastewater, the dosage of the peracetic acid solution is 60–80 μL, and the concentration of the peracetic acid solution is 15–20 wt%.

5. A method for treating wastewater using molybdenum carbide-activated peracetic acid according to claim 1, 3, or 4, characterized in that, The molar ratio of peracetic acid to coexisting hydrogen peroxide in the peracetic acid solution is 0.35–0.40:

1.

6. The method for treating wastewater by molybdenum carbide-activated peracetic acid according to claim 1, characterized in that, The concentration of the pollutant is 2–10 mg / L.

7. A method for treating wastewater using molybdenum carbide-activated peracetic acid according to claim 1 or 6, characterized in that, The contaminants include sulfamethoxazole, naproxen, methylene blue, and rhodamine B.

8. The method for treating wastewater by molybdenum carbide-activated peracetic acid according to claim 1, characterized in that, The dosage of molybdenum carbide in the wastewater is 0.2–1.0 g / L.

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