A method for degrading SMX in water using a NaClO enhanced system

Abstract

A method for degrading smolybdenum (SMX) in water using a NaClO-enhanced NaNa system is disclosed, relating to the field of water treatment technology. The method involves adding NaNa to a phosphate buffer solution of SMX to be treated, adjusting the pH, adding NaClO, and stirring the reaction. This invention utilizes activated NaClO to rapidly degrade SMX, is simple to operate, and exhibits excellent removal performance. Furthermore, this system can effectively remove SMX even in high-salt conditions and can also be used to degrade other pollutants.

Description

Technical Field

[0001] This invention relates to the field of water treatment, and more particularly to a method for degrading sulfamethoxazole (SMX) in water using a pyridine-3-carboxylic acid (NA)-enhanced sodium hypochlorite (NaClO) system. Background Technology

[0002] Sulfonamides (SAs) are synthetic broad-spectrum antibiotics with advantages such as broad antibacterial spectrum, stability, and ease of use. However, the widespread use and difficulty in complete degradation of SAs lead to their high detection rate in water bodies. SA pollution can induce drug resistance in natural microorganisms, leading to the emergence of resistance genes. Furthermore, studies by Champage et al. have shown that SAs may have direct neurotoxicity, posing a threat to ecosystem balance and human health. SMX, a typical sulfonamide antibiotic, is widely used in livestock and poultry farming. Livestock and poultry metabolize SMX to a limited extent, with most (75%–90%) excreted as the original drug or incomplete metabolites, resulting in its high detection rate in water bodies. Even at low doses, SMX retains biological activity, and within a relatively low concentration range, it may still pose ecotoxicological risks to aquatic organisms, thus potentially harming human health.

[0003] Because SMX is biotoxic, its presence in wastewater can reduce sludge activity and even cause it to disintegrate and deteriorate, leading to a decrease in effluent quality. Furthermore, traditional biological wastewater treatment technologies primarily remove SMX and other pollutants through adsorption, which can enrich these pollutants in the residual sludge. However, the SMX accumulated in the residual sludge still poses a threat to environmental and ecological safety. Compared to traditional biological treatment technologies, advanced oxidation technologies utilize strong oxidizing agents to convert antibiotics into non-toxic small-molecule organic compounds or small-molecule inorganic compounds such as carbon dioxide, showing great potential for application in antibiotic wastewater treatment. However, some advanced oxidation technologies based on oxidants such as H₂O₂, PMS, and O₃ suffer from high oxidant costs and inconvenient transportation and storage, thus increasing wastewater treatment costs. In contrast, NaClO exhibits strong oxidizing properties in both weakly alkaline and acidic solutions, offering advantages such as low cost, strong bactericidal ability, and ease of production. Summary of the Invention

[0004] The purpose of this invention is to solve the above-mentioned problems in the prior art and provide a method for rapidly degrading SMX in water, which uses environmentally friendly NA-enhanced NaClO to efficiently degrade SMX pollutants.

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

[0006] A highly efficient method for degrading SMX involves adding Na to a phosphate buffer solution containing the SMX to be treated, adjusting the pH, adding NaClO, and stirring the reaction to achieve the removal of organic pollutants.

[0007] The SMX phosphate buffer solution contains 1.0 μM SMX and 10 mM phosphate buffer solution.

[0008] The concentration of NaClO is 7.5 μM.

[0009] The concentration of the NA activator is 10 μM.

[0010] The pH is 4.0 to 8.0.

[0011] The stirring reaction time shall not exceed 3 minutes.

[0012] The stirring reaction time is 1 minute.

[0013] The method for determining the concentration of organic pollutants in this invention is high-performance liquid chromatography (HPLC, Shimadzu LC-20AD), which is coupled with an Agilent XDB-C18 column (ZORBAX Eclipse, 4.6 × 150 mm, particle size 5.74 μm) and a diode array detector. The method for determining the content of SMX is as follows: the mobile phase is ultrapure water and methanol in a ratio of 55 / 45, the flow rate is 0.8 mL / min, the elution time is 4.19 min, and the detection wavelength is 257 nm.

[0014] Compared with the prior art, the beneficial effects achieved by the technical solution of this invention are:

[0015] This invention is the first to utilize NA-activated NaClO for the removal of SMX, an organic pollutant in water. Under conditions of 10 μM NA, 7.5 μM NaClO, and pH 6.0, it effectively removes SMX, and the system is unaffected by inorganic anions in the aquatic environment. Furthermore, the NA-enhanced NaClO system can be used to degrade other pharmaceuticals, demonstrating a wide range of applications. Attached Figure Description

[0016] Figure 1 A comparison graph showing the effects of different ligands on the degradation of SMX by NaClO.

[0017] Figure 2 The graph shows the effect of pH on the degradation of SMX by Na / NaClO.

[0018] Figure 3 For Cl - The effect of ions on the degradation of SMX in the NA / NaClO system.

[0019] Figure 4 NO3 - The effect of ions on the degradation of SMX in the NA / NaClO system.

[0020] Figure 5 SO4 2- The effect of ions on the degradation of SMX in the NA / NaClO system.

[0021] Figure 6 A schematic diagram illustrating the degradation effect of PPN by the NA / NaClO system.

[0022] Figure 7 A schematic diagram illustrating the degradation effect of DCF by the NA / NaClO system.

[0023] Figure 8 This is a schematic diagram illustrating the degradation effect of RhB by the NA / NaClO system.

[0024] Figure 9 A schematic diagram illustrating the degradation effect of MG by the NA / NaClO system. Detailed Implementation

[0025] To make the technical problems, technical solutions and beneficial effects of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0026] Example 1

[0027] The wastewater to be treated is an SMX phosphate buffer solution, wherein the SMX concentration is 1 μM and the phosphate solution concentration is 10 mM.

[0028] This embodiment was carried out as follows: NA (10 μM) was added to the wastewater to be treated and stirred thoroughly. The pH was adjusted to 6.0 with phosphoric acid, and the mixture was stirred for 1 minute. After thorough mixing, NaClO (7.5 μM) was added to the solution, and the mixture was stirred for 3 minutes. A sample was taken to measure the SMX concentration. Figure 1 As shown, the removal rate of SMX reached 100% after 3 minutes of reaction.

[0029] Furthermore, this invention verified the removal efficiency of different ligands for SMX using NA / NaClO, pyridine-2-carboxylic acid (PICA) / NaClO, pyridine-4-carboxylic acid (IA) / NaClO, 2-hydroxypyridine (2-HP) / NaClO, 3-hydroxypyridine (3-HP) / NaClO, 4-hydroxypyridine (4-HP) / NaClO, 2-aminopyridine (2-AP) / NaClO, 3-aminopyridine (3-AP) / NaClO, 4-aminopyridine (4-AP) / NaClO, pyridine / NaClO, piperidinecarboxylic acid (PA) / NaClO, picolinic acid N-oxide (PCA-N) / NaClO, and benzoic acid (BA) / NaClO systems. See also... Figure 1 The results showed that different functional groups and their positions had different enhancing effects on NaClO; pyridine and benzoic acid did not promote the oxidation of SMX by NaClO, indicating that pyridine nitrogen and carboxylic acid in NaClO both played important roles.

[0030] Example 2

[0031] pH has a significant impact on this type of oxidation reaction; therefore, simulations of various pH values ​​are provided. Figure 2 The results showed that the more acidic the conditions, the stronger the effect of NA in promoting the oxidation of NaClO.

[0032] Example 3

[0033] This invention verifies whether the system can be applied to real-world aquatic environments to simulate inorganic anions (Cl). - NO3 - SO4 2- For the effects of ions, see [link / reference]. Figures 3-5 The results showed that these three types of ions had no significant inhibitory effect on the system.

[0034] Example 4

[0035] This invention verifies whether the system can be applied to other pollutants. Tests were conducted using a Na / NaClO system to degrade propranolol (PPN), diclofenac (DCF), rhodamine B (RhB), and malachite green (MG). See [link to relevant documentation]. Figures 6-9 The results showed that NA could promote the degradation of various pollutants by NaClO, but the enhancement effects varied.

[0036] The PPN content was determined by high performance liquid chromatography (HPLC). The mobile phase was ultrapure water and methanol in a 50 / 50 ratio. The flow rate was 0.8 mL / min, the elution time was 5.81 min, and the measurement wavelength was 289 nm.

[0037] The method for determining the content of DCF is as follows: high performance liquid chromatography is used. The mobile phase is 1‰ acetic acid aqueous solution and methanol in a ratio of 25 / 75. The flow rate is 1 mL / min, the peak elution time is 4.5 min, and the wavelength is 276 nm.

[0038] RhB and MG were determined using ultraviolet light to measure the concentration of the solution.

[0039] This invention uses pyridine compounds as catalysts, with different ligands exhibiting varying enhancing effects on NaClO. NA (nitrogenous acid) shows a significant enhancing effect and is itself biodegradable or hydrolyzed, causing no environmental pollution. This invention selects SMX from saturated salicylic acids (SAs) as the target product to study the degradation efficiency and influencing factors of the NA-enhanced NaClO system. Experiments explore the effects of different conditions, such as initial pH, inorganic anion concentration and type, on the SMX degradation effect of the NA-enhanced NaClO system, providing a new method and theoretical basis for the treatment of SA-polluted water bodies.

Claims

1. A method for degrading sulfamethoxazole in water using a pyridine-3-carboxylic acid-enhanced NaClO system, characterized in that: Add pyridine-3-carboxylic acid to the sulfamethoxazole phosphate buffer solution to be treated, adjust the pH to 4.0~8.0, add NaClO, and stir to react.

2. The method for degrading sulfamethoxazole in water using a pyridine-3-carboxylic acid-enhanced NaClO system as described in claim 1, characterized in that: The sulfamethoxazole phosphate buffer solution contains 10 mM phosphate.

3. The method for degrading sulfamethoxazole in water using a pyridine-3-carboxylic acid-enhanced NaClO system as described in claim 1, characterized in that: The concentration of sulfamethoxazole in the sulfamethoxazole phosphate buffer solution is 1 μM.

4. The method for degrading sulfamethoxazole in water using a pyridine-3-carboxylic acid-enhanced NaClO system as described in claim 1, characterized in that: The concentration of the pyridine-3-carboxylic acid is 10 mM.

5. The method for degrading sulfamethoxazole in water using a pyridine-3-carboxylic acid-enhanced NaClO system as described in claim 1, characterized in that: The concentration of NaClO is 7.5 mM.

6. The method for degrading sulfamethoxazole in water using a pyridine-3-carboxylic acid-enhanced NaClO system as described in claim 1, characterized in that: The pH is 6.

0.

7. The method for degrading sulfamethoxazole in water using a pyridine-3-carboxylic acid-enhanced NaClO system as described in claim 1, characterized in that: The stirring reaction time shall not exceed 3 minutes.

8. The method for degrading sulfamethoxazole in water using a pyridine-3-carboxylic acid-enhanced NaClO system as described in claim 1, characterized in that: The stirring reaction time is 1 minute.

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