A method for degrading sulfamethoxazole using peroxyacetic acid under neutral pH conditions

Abstract

The application discloses a method for degrading sulfamethoxazole under neutral pH conditions by using peroxyacetic acid, and the method is characterized in that: firstly, protocatechuic acid is chelated with ferric iron in proportion, and then the protocatechuic acid-ferric iron chelate is used to activate peroxyacetic acid, so as to generate active species mainly in the form of high-valence iron under neutral pH conditions, and the active species are used to oxidize and degrade sulfamethoxazole in water. It is found that the protocatechuic acid can significantly improve the efficiency of the ferric iron-activated peroxyacetic acid method for degrading sulfamethoxazole in water and the anti-water quality background interference ability, and greatly widen the effective pH application range. The method solves the problems of slow reaction rate, poor anti-interference ability and narrow pH application range of the ferric iron-activated peroxyacetic acid method, and has the advantages of economic efficiency, simple operation, green environmental protection and the like, and has a wide application prospect in the treatment of organic wastewater containing sulfamethoxazole, such as medical wastewater and aquaculture wastewater.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, specifically relating to a method for degrading sulfamethoxazole in water using peracetic acid under neutral pH conditions. Background Technology

[0002] Sulfamethoxazole is widely used in medicine, animal husbandry, and aquaculture, and is one of the most widely used antibiotics. However, because sulfamethoxazole cannot be completely metabolized by humans and animals, and traditional wastewater treatment methods have limited removal efficiency, it is one of the most frequently detected antibiotics in aquatic environments such as surface water, groundwater, and sewage treatment plant effluent. Reports indicate that concentrations of sulfamethoxazole detected in sewage treatment plant effluent and surface water reach the ng / L and even μg / L levels. Prolonged human exposure to sulfamethoxazole in the aquatic environment can lead to developmental abnormalities, reduced growth rates, and decreased reproductive capacity. Simultaneously, sulfamethoxazole also has negative effects on aquatic organisms, promoting the development of antibiotic-resistant bacteria in the aquatic environment, which may lead to the spread of antibiotic-resistant infections among aquatic and terrestrial organisms, including humans. Therefore, it is necessary to develop efficient methods for removing sulfamethoxazole from pharmaceutical, aquaculture, and other organic wastewater.

[0003] Existing methods for the degradation of sulfamethoxazole in water include:

[0004] CN202111522306.X discloses a method for the synergistic thermal activation of persulfate with wood sponge to degrade sulfamethoxazole. After chemical treatment of wood blocks, the blocks are first coated with a dopamine solution, then impregnated with ferric nitrate nonahydrate and cobalt nitrate hexahydrate, washed with sodium hydroxide solution, freeze-dried, further impregnated with urea, and calcined under an inert gas atmosphere to obtain a wood sponge catalyst. The wood sponge catalyst is mixed with persulfate, and sulfamethoxazole is degraded under pH 3-9 and temperature 30-60℃. Results of the catalytic degradation reaction of sulfamethoxazole show that this method can achieve efficient degradation of sulfamethoxazole in water. However, the preparation process of the catalyst wood sponge involves many materials and equipment, resulting in high preparation costs and operational difficulties.

[0005] CN201610107207.8 discloses a method and apparatus for the biodegradation of sulfamethoxazole. This method involves seed culture to obtain secondary seeds of *Alcaligenes faecalis* and *Pseudomonas denitrificans*, which are then used to prepare a sulfamethoxazole degradation solution. The apparatus and method of this invention prevent the two bacterial cells from contacting each other, reducing the inhibition of biomass caused by cell contact and thus ensuring efficient degradation of sulfamethoxazole. However, the microorganisms in this method are greatly affected by environmental factors such as temperature and pH, limiting its application in actual water bodies with highly variable environmental conditions.

[0006] "Degradation of sulfamethoxazole in reclaimed water by UV / NaClO advanced oxidation process", Yang Haiyan et al., Journal of Zhejiang University (Engineering Science) 2019, No. 1, proposes a method for degrading sulfamethoxazole in water using a UV / NaClO advanced oxidation process, and studies the factors affecting the degradation of sulfamethoxazole by the UV / NaClO process. Experimental studies have shown that the UV / NaClO process can effectively remove sulfamethoxazole, and the reaction process conforms to the pseudo-first-order reaction kinetics. When the pH is 3-8, sulfamethoxazole has a high degradation rate. However, the UV / NaClO process is greatly affected by natural organic matter, inorganic ions, etc., and the degradation efficiency of sulfamethoxazole in actual water quality background is not good. SUMMARY

[0007] The purpose of the present application is to provide a method for degrading sulfamethoxazole under neutral pH conditions using peroxiacetic acid.

[0008] The technical solution of the present application comprises the following steps:

[0009] S1, preparing a protocatechuic acid-ferric iron chelate solution: mixing and dissolving protocatechuic acid and ferric salt in a certain proportion and standing for a period of time to obtain a protocatechuic acid-ferric iron chelate solution;

[0010] S2, degrading sulfamethoxazole: adding peroxiacetic acid and the protocatechuic acid-ferric iron chelate solution prepared in S1 into wastewater containing sulfamethoxazole, and mixing uniformly to rapidly degrade sulfamethoxazole in water in a short time.

[0011] Preferably, the neutral pH condition is pH 5.0-9.0.

[0012] Further preferably, the neutral pH condition is pH 6.0-8.0.

[0013] Preferably, in step S1, the ferric salt is any one of ferric chloride and ferric sulfate.

[0014] Further preferably, the ferric salt is ferric sulfate.

[0015] Preferably, in step S1, the standing time is 20-60 minutes.

[0016] Further preferably, the standing time is 30-60 minutes.

[0017] Preferably, in step S1, the mass ratio of protocatechuic acid to ferric iron in the protocatechuic acid-ferric iron chelate solution is 1-10:1.

[0018] It is further preferred that the mass ratio of protocatechuic acid to ferric iron in the protocatechuic acid-ferric iron chelate solution is 5-10:1.

[0019] Preferably, in step S2, the concentration of sulfamethoxazole is 0.1-5 mg / L.

[0020] It is further preferred that the concentration of sulfamethoxazole is 1-4 mg / L.

[0021] Preferably, in step S2, the concentration of protocatechuic acid in the wastewater is 0.5-50 mg / L.

[0022] It is further preferred that the concentration of protocatechuic acid in the wastewater is 5-25 mg / L.

[0023] Preferably, in step S2, the concentration of ferric iron in the wastewater is 0.5-5 mg / L.

[0024] It is further preferred that the concentration of ferric iron in the wastewater is 1-2.5 mg / L.

[0025] Preferably, in step S2, the concentration of peracetic acid in the wastewater is 5-30 mg / L.

[0026] It is further preferred that the concentration of peracetic acid in the wastewater is 10-20 mg / L.

[0027] Preferably, in step S2, the reaction time is 5-30 minutes.

[0028] It is further preferred that, in step S2, the reaction time is 10-30 minutes.

[0029] Technical principle of the present application: In the ferric iron activated peracetic acid method, protocatechuic acid is introduced to form a protocatechuic acid-ferric iron chelate, which can prevent the precipitation of ferric iron under neutral pH conditions and activate peracetic acid to produce active species mainly in the form of high-valence iron to remove sulfamethoxazole under neutral pH conditions. The principle is shown in the schematic diagram Figure 1 .

[0030] Compared with the prior art, the present application has the following advantages:

[0031] (1) The present application realizes efficient degradation of sulfamethoxazole under neutral pH conditions by adding protocatechuic acid in the ferric iron activated peracetic acid method, without the need to add acidic substances to adjust the pH to be acidic before the reaction and to add alkaline substances to adjust the pH to be neutral after the reaction, thereby greatly reducing the economic cost of treating sulfamethoxazole wastewater.

[0032] (2) The main active species generated by the present application is high-valence iron which has strong selective reaction characteristics for pollutants, and has strong anti-interference ability for common anions and humic acid in actual water bodies, and has broad application prospects.

[0033] (3) The present application strengthens the generation of active species and the degradation of sulfamethoxazole pollutants in the method of ferric iron activated peroxyacetic acid, greatly shortening the required time of reaction, and the shortest required time of the present application is 10 minutes.

[0034] (4) The protocatechuic acid added in the present application belongs to natural phenolic acid, which widely exists in plants and human food, is green and environmentally friendly, has no secondary pollution, and has significant environmental benefits. BRIEF DESCRIPTION OF DRAWINGS

[0035] The present application will be further described below in combination with the drawings and examples.

[0036] Figure 1 is a schematic diagram of the principle of the present application.

[0037] Figure 2 is the effect diagram of protocatechuic acid strengthening ferric iron activated peroxyacetic acid method for degrading sulfamethoxazole in the pH range of 6-8.

[0038] Among them, the abscissa represents the reaction time; the ordinate represents the ratio of the concentration of sulfamethoxazole to the initial concentration at the corresponding reaction time.

[0039] Figure 3 is the effect diagram of protocatechuic acid strengthening ferric iron activated peroxyacetic acid method for degrading sulfamethoxazole in the pH range of 6-8.

[0040] Figure 4 is the effect diagram of protocatechuic acid strengthening ferric iron activated peroxyacetic acid method for degrading sulfamethoxazole in the pH range of 6-8. DETAILED DESCRIPTION

[0041] A method for degrading sulfamethoxazole by peroxyacetic acid under neutral pH conditions comprises the following steps:

[0042] S1, preparing a protocatechuic acid-ferric iron chelate solution: mixing and dissolving protocatechuic acid and ferric salt according to a certain ratio and standing for a period of time, and then a protocatechuic acid-ferric iron chelate solution can be obtained;

[0043] S2, degrading sulfamethoxazole: adding peroxyacetic acid and the protocatechuic acid-ferric iron chelate solution prepared in S1 into wastewater containing sulfamethoxazole in sequence, and then uniformly mixing, so that sulfamethoxazole in water can be rapidly degraded in a short time.

[0044] Preferably, the pH neutral condition is pH 5.0-9.0.

[0045] Further preferably, the pH neutral condition is pH 6.0-8.0.

[0046] Preferably, in step S1, the ferric salt is any one of ferric chloride and ferric sulfate.

[0047] Further preferably, the ferric salt is ferric sulfate.

[0048] Preferably, in step S1, the standing time is 20-60 minutes.

[0049] Further preferably, the standing time is 30-60 minutes.

[0050] Preferably, in step S1, the mass ratio of protocatechuic acid to ferric iron in the protocatechuic acid-ferric iron chelate solution is 1-10:1.

[0051] Further preferably, the mass ratio of protocatechuic acid to ferric iron in the protocatechuic acid-ferric iron chelate solution is 5-10:1.

[0052] Preferably, in step S2, the concentration of sulfamethoxazole is 0.1-5 mg / L.

[0053] Further preferably, the concentration of sulfamethoxazole is 1-4 mg / L.

[0054] Preferably, in step S2, the concentration of protocatechuic acid is 0.5-50 mg / L.

[0055] Further preferably, the concentration of protocatechuic acid is 5-25 mg / L.

[0056] Preferably, in step S2, the concentration of ferric iron is 0.5-5 mg / L.

[0057] Further preferably, the concentration of ferric iron is 1-2.5 mg / L.

[0058] Preferably, in step S2, the concentration of peroxyacetic acid is 5-30 mg / L.

[0059] Further preferably, the concentration of peroxyacetic acid is 10-20 mg / L.

[0060] Preferably, in step S2, the reaction time is 5-30 minutes.

[0061] Further preferably, in step S2, the reaction time is 10-30 minutes.

[0062] The application will be further described in connection with specific examples, which are only intended to illustrate the application and not to limit the application to the following examples.

[0063] Example 1 Preparation of protocatechuic acid-ferric iron chelate solution

[0064] Take 2.5 g of protocatechuic acid and 1 g of ferric sulfate and dissolve them in 1 L of distilled water, and let it stand for 60 minutes to prepare protocatechuic acid-ferric iron chelate solution 1#.

[0065] Example 2 Preparation of protocatechuic acid-ferric iron chelate solution

[0066] Take 1.5 g of protocatechuic acid and 1 g of ferric sulfate and dissolve them in 1 L of distilled water, and let it stand for 60 minutes to prepare protocatechuic acid-ferric iron chelate solution 2#.

[0067] Example 3 Preparation of protocatechuic acid-ferric iron chelate solution

[0068] Take 1.25 g of protocatechuic acid and 1 g of ferric sulfate and dissolve them in 1 L of distilled water, and let it stand for 60 minutes to prepare protocatechuic acid-ferric iron chelate solution 3#.

[0069] Example 4 Preparation of protocatechuic acid-ferric iron chelate solution

[0070] Take 2.5 g of protocatechuic acid and 1 g of ferric sulfate and dissolve them in 1 L of distilled water, and let it stand for 30 minutes to prepare protocatechuic acid-ferric iron chelate solution 4#.

[0071] Example 5 Preparation of protocatechuic acid-ferric iron chelate solution

[0072] Take 1.5 g of protocatechuic acid and 1 g of ferric sulfate and dissolve them in 1 L of distilled water, and let it stand for 30 minutes to prepare protocatechuic acid-ferric iron chelate solution 5#.

[0073] Example 6 Preparation of protocatechuic acid-ferric iron chelate solution

[0074] Take 1.25 g of protocatechuic acid and 1 g of ferric sulfate and dissolve them in 1 L of distilled water, and let it stand for 30 minutes to prepare protocatechuic acid-ferric iron chelate solution 6#.

[0075] Example 7 Degradation of sulfamethoxazole

[0076] In 100 mL of wastewater with pH of 7.0 and sulfamethoxazole concentration of 1.27 mg / L, 1 mL of 1.5 g / L peroxoacetic acid solution was added, and then 1 mL of 1# protocatechuic acid-ferric iron chelate solution was added. After 10 minutes of reaction, the degradation rate of sulfamethoxazole reached 94%, and the apparent reaction rate constant was 0.2631 min -1 .

[0077] Example 8 Degradation of sulfamethoxazole

[0078] In 100 mL of wastewater with pH of 8.0 and sulfamethoxazole concentration of 1.27 mg / L, 1 mL of 1.5 g / L peroxyacetic acid solution was added, followed by 1 mL of 1# protocatechuic acid-ferric ion chelate solution. After 10 minutes of reaction, the degradation rate of sulfamethoxazole reached 92%, and the apparent reaction rate constant was 0.2489 min -1 .

[0079] Example 9 Degradation of sulfamethoxazole

[0080] In 100 mL of wastewater with pH of 6.0 and sulfamethoxazole concentration of 1.27 mg / L, 1 mL of 1.5 g / L peroxyacetic acid solution was added, followed by 1 mL of 1# protocatechuic acid-ferric ion chelate solution. After 10 minutes of reaction, the degradation rate of sulfamethoxazole reached 92%, and the apparent reaction rate constant was 0.2454 min -1 .

[0081] It can be found from Figure 2 that by adding protocatechuic acid in the method of ferric ion activated peroxyacetic acid, high-efficiency degradation of sulfamethoxazole under neutral pH conditions (6-8) can be achieved, i.e. the economic cost of adjusting pH before and after treating sulfamethoxazole wastewater can be saved in actual application.

[0082] Example 10 Degradation of sulfamethoxazole

[0083] In 100 mL of wastewater with pH of 7.0 and sulfamethoxazole concentration of 1.27 mg / L, 1 mL of 1.5 g / L peroxyacetic acid solution and 1 mL of 29.2 g / L sodium chloride solution were added, followed by 1 mL of 1# protocatechuic acid-ferric ion chelate solution. After 10 minutes of reaction, the degradation rate of sulfamethoxazole reached 92%, and the apparent reaction rate constant was 0.2317 min -1 .

[0084] Example 11 Degradation of sulfamethoxazole

[0085] In 100 mL of wastewater with pH of 7.0 and sulfamethoxazole concentration of 1.27 mg / L, 1 mL of 1.5 g / L peroxyacetic acid solution and 1 mL of 42.0 mg / L sodium carbonate solution were added, followed by 1 mL of 1# protocatechuic acid-ferric ion chelate solution. After 10 minutes of reaction, the degradation rate of sulfamethoxazole reached 91%, and the apparent reaction rate constant was 0.2382 min -1 .

[0086] Example 12 Degradation of sulfamethoxazole

[0087] In 100 mL of wastewater with pH of 7.0 and sulfamethoxazole concentration of 1.27 mg / L, 1 mL of 1.5 g / L peroxyacetic acid solution and 1 mL of 71.0 g / L sodium phosphate dibasic solution were added, and then 1 mL of 1# protocatechuic acid-ferric ion chelate solution was added. After 10 minutes of reaction, the degradation rate of sulfamethoxazole reached 93%, and the apparent reaction rate constant was 0.2488 min -1 .

[0088] Example 13 Degradation of sulfamethoxazole

[0089] In 100 mL of wastewater with pH of 7.0 and sulfamethoxazole concentration of 1.27 mg / L, 1 mL of 1.5 g / L peroxyacetic acid solution and 1 mL of 42.5 g / L sodium nitrate solution were added, and then 1 mL of 1# protocatechuic acid-ferric ion chelate solution was added. After 10 minutes of reaction, the degradation rate of sulfamethoxazole reached 90%, and the apparent reaction rate constant was 0.2143 min -1 .

[0090] Example 14 Degradation of sulfamethoxazole

[0091] In 100 mL of wastewater with pH of 7.0 and sulfamethoxazole concentration of 1.27 mg / L, 1 mL of 1.5 g / L peroxyacetic acid solution and 1 mL of 0.5 g / L humic acid solution were added, and then 1 mL of 1# protocatechuic acid-ferric ion chelate solution was added. After 10 minutes of reaction, the degradation rate of sulfamethoxazole reached 88%, and the apparent reaction rate constant was 0.2131 min -1 .

[0092] It can be found from Figure 3 Comparing with Example 7 without common anions and humic acid, Examples 10-14 show the same excellent effect on the degradation of sulfamethoxazole, that is, the protocatechuic acid-enhanced ferric ion activation of peroxyacetic acid method has strong anti-interference ability to common anions and humic acid in water.

[0093] Example 15 Degradation of sulfamethoxazole

[0094] In 100 mL of surface water with pH of 7.0 and sulfamethoxazole concentration of 1.27 mg / L, 1 mL of 1.5 g / L peroxyacetic acid solution was added, and then 1 mL of 1# protocatechuic acid-ferric ion chelate solution was added. After 10 minutes of reaction, the degradation rate of sulfamethoxazole reached 92%, and the apparent reaction rate constant was 0.2406 min -1 .

[0095] Example 16 Degradation of sulfamethoxazole

[0096] In 100 mL of groundwater with pH 7.0 and sulfamethoxazole concentration of 1.27 mg / L, 1 mL of 1.5 g / L peroxyacetic acid solution was added, followed by 1 mL of 1# protocatechuic acid-ferric ion chelate solution. After 30 minutes of reaction, the degradation rate of sulfamethoxazole reached 93%, and the apparent reaction rate constant was 0.2444 min -1 .

[0097] Example 17 Degradation of sulfamethoxazole

[0098] In 100 mL of secondary sedimentation tank effluent with pH 7.0 and sulfamethoxazole concentration of 1.27 mg / L, 1 mL of 1.5 g / L peroxyacetic acid solution was added, followed by 1 mL of 1# protocatechuic acid-ferric ion chelate solution. After 30 minutes of reaction, the degradation rate of sulfamethoxazole reached 94%, and the apparent reaction rate constant was 0.2633 min -1 .

[0099] It can be found from Figure 4 that compared with sulfamethoxazole wastewater prepared with distilled water in Example 7, the degradation of sulfamethoxazole in Examples 15-17 shows equally excellent effect in the background of actual water quality, indicating that the application of protocatechuic acid enhanced ferric ion activated peroxyacetic acid method in actual water body has a very broad prospect.

Claims

1. A method for degrading sulfamethoxazole under neutral pH conditions by using peroxyacetic acid, comprising the following steps: S1, preparing a protocatechuic acid-ferric ion chelate solution: mixing and dissolving protocatechuic acid and a ferric salt in a certain ratio and standing for a period of time to obtain a protocatechuic acid-ferric ion chelate solution; the mass ratio of protocatechuic acid to ferric ion in the protocatechuic acid-ferric ion chelate solution is 1-10:1; S2, degrading sulfamethoxazole: adding peroxyacetic acid and the protocatechuic acid-ferric ion chelate solution prepared in S1 into wastewater containing sulfamethoxazole in sequence, and then rapidly degrading sulfamethoxazole in the wastewater after mixing uniformly; the concentration of sulfamethoxazole is 0.1-5 mg / L; the concentration of protocatechuic acid in the wastewater is 0.5-50 mg / L; the concentration of ferric ion in the wastewater is 0.5-5 mg / L; the amount of peroxyacetic acid in the wastewater ranges from 5 to 30 mg / L; and the reaction time is 5-30 minutes; the neutral pH condition is pH 5.0-9.

0.

2. The method for degrading sulfamethoxazole using peroxyacetic acid under neutral pH conditions according to claim 1, characterized in that, In step S1, the ferric salt is any one of ferric chloride, ferric sulfate and ferric nitrate.

3. The method for degrading sulfamethoxazole using peroxyacetic acid under neutral pH conditions according to claim 1, characterized in that, In step S1, the standing time is 20-60 minutes.

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