Method for activating persulfate oxidation by bordeaux mixture to inactivate pathogenic microorganisms in water body and application thereof

Abstract

The present application belongs to the technical field of inactivation of pathogenic microorganisms in water bodies, and discloses a method for inactivating pathogenic microorganisms in water bodies by activating persulfate oxidation with Bordeaux mixture and application thereof. The method is as follows: Bordeaux mixture is added to water bodies contaminated with pathogenic microorganisms, and then a persulfate solution is added to form a reaction system, and the reaction system is shaken at room temperature to simulate real water bodies, so as to inactivate the pathogenic microorganisms. The present application provides a new method for inactivating pathogenic microorganisms such as Escherichia coli and Enterococcus faecalis in water bodies. Sulfate radicals and hydroxyl radicals are generated by activating persulfate with Bordeaux mixture, and alkaline copper sulfate and calcium sulfate precipitate and flocculate and settle the pathogenic bacteria residues in cooperation. The inactivation effect of the Bordeaux / PS system within 5 minutes reaches more than 99%.

Description

Technical Field

[0001] This invention belongs to the field of aquatic pathogenic microorganism inactivation technology, and relates to a method and application of Bordeaux mixture-activated persulfate oxidation to inactivate aquatic pathogenic microorganisms. Background Technology

[0002] Pathogenic microorganisms are microorganisms that can cause diseases in humans, animals, or plants, and mainly include bacteria, viruses, fungi, and parasites. They infect hosts through various routes, disrupting normal physiological functions and leading to disease or even death. The harm caused by aquatic pathogenic microorganisms is widespread and highly pathogenic, posing a serious threat to water safety and human health.

[0003] Currently, commonly used water disinfectants and methods mainly include liquid chlorine, chlorine dioxide, hypochlorous acid, ozone, and ultraviolet light. While these methods are effective in inactivating microorganisms, they suffer from high costs, high energy consumption, and the accumulation of disinfection byproducts. Advanced oxidation processes based on oxidants such as persulfate offer advantages such as rapid and effective inactivation, wide applicability, and simple engineering operation. Persulfate is easy to transport, relatively stable, and readily soluble in water. It can be activated through heat, alkali, transition metal ions, ultrasound, and ultraviolet light to generate sulfate radicals, hydroxyl radicals, and superoxide radicals, thereby inactivating pathogenic microorganisms. Compared to other activation methods, the activation of persulfate by transition metals such as iron and copper generates more highly reactive species such as sulfate radicals and hydroxyl radicals, making it simpler to apply, easier to operate, and more suitable for actual water body application conditions.

[0004] Currently, the transition metal used in the technology of activating persulfate to inactivate pathogenic microorganisms in water bodies is mainly iron. (Reference) PF The paper, "Application of iron-activated persulfate formunicipal wastewater disinfection" (Journal of Hazardous Materials 426(2022):127989), reports that at a persulfate concentration of 3 mmol / L and Fe... 2+ At a concentration of 0.75 mmol / L, the total heterotrophic organism removal rate was 91% within one hour, and the E. coli concentration was below 10 CFU / 100 mL. Patent (CN113287632A) developed a red tide algae remover based on tannic acid coupled with ferrous iron-activated persulfate and its application, achieving algae removal within 300 minutes for organisms with a density of 10... 9 The removal rate of *Heterosigma rubrum* cells / L in the above system can reach 98%. 2+ It is rapidly oxidized to Fe, which has lower catalytic efficiency. 3+This leads to a decrease in efficiency in the later stages of the reaction, often requiring the addition of excessive Fe. 2+ This not only greatly increased costs, but also resulted in excessive Fe... 2+ Iron salts may react with free radicals, consuming them and reducing oxidation efficiency. The improvement in pathogen inactivation is not ideal, and residual iron salts degrade water quality. The literature (Zhigang Yu, et al. “Synergistic effect of sulfidated nano zerovalent iron and persulfate on inactivating antibiotic resistant bacteria and antibiotic resistance genes” Water Research 198(2021):117141) proposes using S-nZVI to activate persulfate and inactivate pathogens, completely inactivating antibiotic-resistant bacteria within 10 minutes. However, nano-zero-valent iron is costly and difficult to apply on a large scale. Furthermore, patent (CN119215888A) discloses a nano-carbon supported ruthenium cluster nanocatalyst, its preparation method, and its application. This system efficiently activates persulfate to inactivate E. coli by preparing a nano-carbon supported ruthenium cluster nanocatalyst. Under room temperature and neutral conditions, it inactivates 10... 7 Escherichia coli CFU / mL. Patent (CN201911116524.6) discloses a method for activating persulfate with a metal sulfide compound to inactivate E. coli. This system utilizes tungsten disulfide in synergistic with iron ions to efficiently catalyze the decomposition of persulfate, generating sulfate and hydroxyl radicals to inactivate bacteria. Specifically, within 1 minute, PMS / Fe... 3+ The / WS2 system achieved an inactivation rate of over 99%. However, ruthenium and tungsten can cause secondary pollution to water bodies and are costly.

[0005] Copper is also a commonly used persulfate transition metal activator. The literature (Hye-Jin Lee, et al. “Inactivation of bacterial planktonic cells and biofilms by Cu(II)-activated peroxymonosulfate in the presence of chloride ion” Chemical Engineering Journal 380(2020):122468) reports that Cu(II)-activated PS systems can also be used to inactivate Pseudomonas aeruginosa. When the Cu(II) concentration is higher than 5 μmol / L, 3.1 log units of Pseudomonas aeruginosa are inactivated after 10 min, but the inactivation effect is poor when the Cu(II) concentration is lower. Copper ions have strong biotoxicity, and excessive residues can damage aquatic ecosystems.

[0006] Transition metals such as iron and aluminum salts can also remove pathogenic microorganisms from water bodies through flocculation and sedimentation. A study (Guangqiang Cai, et al. “Control for chlorine-resistant spore-forming bacteria by the coupling of pre-oxidation and coagulation sedimentation, and UV-AOP-senhanced inactivation in drinking water treatment” Water Research 219(2022), 118540) reported that when 30 mg / L polyaluminum chloride was used alone, the spore flocculation removal efficiency of SFB strain was approximately 2 log, while when 20 mg / L polyaluminum chloride and 0.08 mg / L polyacrylamide were used simultaneously, the spore flocculation removal efficiency reached approximately 3.15 log. However, flocculants have low removal rates for pathogenic microorganisms in water bodies, and the settled microorganisms retain biological activity, posing a threat to water quality safety once they detach from the flocculant and return to the water.

[0007] Therefore, developing a low-dosage, high-efficiency transition metal activation persulfate oxidation inactivation technology for pathogenic microorganisms in water is of significant practical importance. This invention proposes a method and application for Bordeaux mixture-activated persulfate oxidation inactivation of pathogenic microorganisms in water, achieving long-lasting activation of persulfate with low-dosage transition metals for efficient oxidation inactivation. Bordeaux mixture is a colloidal suspension prepared from copper sulfate (CuSO4), quicklime (CaO), and water in a specific ratio, with its main components being basic copper sulfate [Cu(OH)2]3·CuSO4 and CaSO4. The Bordeaux mixture-activated persulfate inactivation technology of this invention, on the one hand, utilizes the slow dissociation and release of copper ions from basic copper sulfate [Cu(OH)2]3·CuSO4 in water to activate persulfate and generate active species, achieving long-lasting activation and oxidation inactivation while reducing the dosage of copper activator. On the other hand, the basic copper sulfate [Cu(OH)2]3·CuSO4 and CaSO4 in the activator have flocculation and sedimentation activities, which can flocculate and separate the inactivated pathogenic microorganism residues, reducing the consumption of oxidizing active species and the release of copper ions from the residues. This method is simple to apply, easy to operate, and meets the actual water body application conditions. Summary of the Invention

[0008] This invention proposes a method and application for activating persulfate with Bordeaux mixture to oxidize and inactivate pathogenic microorganisms in aquatic bodies. This method achieves long-term activation and efficient oxidation of persulfate with low-dosage transition metals to inactivate pathogenic microorganisms in water. The Bordeaux mixture activation technology for inactivating persulfate in aquatic pathogenic microorganisms utilizes, on the one hand, the slow dissociation and release of copper ions from basic copper sulfate [Cu(OH)2]3·CuSO4 in water to activate persulfate and generate active species, resulting in a long-term activated oxidation and inactivation reaction while reducing the amount of copper activator required. On the other hand, the basic copper sulfate [Cu(OH)2]3·CuSO4 and CaSO4 in the activator have flocculation and sedimentation activity, which can flocculate and separate the inactivated pathogenic microorganism residues, reducing the consumption of oxidizing active species and the release of copper ions from the residues. This method is simple to apply, easy to operate, and suitable for practical water body applications.

[0009] The technical solution of this invention:

[0010] A method for activating persulfate oxidation with Bordeaux mixture to inactivate pathogenic microorganisms in water bodies, comprising the following steps:

[0011] (1) Dissolve copper sulfate and calcium oxide in water in a certain proportion and stir to obtain Bordeaux mixture;

[0012] (2) Bordeaux mixture and persulfate solution were added simultaneously to the water sample contaminated with pathogens to construct a Bordeaux mixture-activated persulfate system to effectively inactivate pathogens.

[0013] The Bordeaux mixture is any one of equal volume Bordeaux mixture, double volume Bordeaux mixture, or multi-volume Bordeaux mixture; preferably, it is double volume Bordeaux mixture, with a mass ratio of CuSO4:CaO:H2O = 1:2:200.

[0014] The pathogen-contaminated water sample was 10. 7 For water samples contaminated with pathogenic microorganisms at CFU / mL, Escherichia coli and Enterococcus faecalis were used as targets for inactivation.

[0015] The persulfate is any one of sodium persulfate, potassium persulfate, ammonium persulfate, and magnesium persulfate, with sodium persulfate being preferred, and the amount added is 0.5-4 mmol / L.

[0016] The amount of Bordeaux mixture added is 0.05%-0.5%. When the amount of Bordeaux mixture added is small, the number of hydroxyl radicals and sulfate radicals generated in the system is too small, resulting in poor inactivation effect; when the amount of Bordeaux mixture added is too high, the concentration of copper ions in the system is high, which will cause secondary pollution; the preferred addition amount is 0.1%.

[0017] The beneficial effects of this invention: This invention provides a novel method for inactivating aquatic pathogenic microorganisms such as *Escherichia coli* and *Enterococcus faecalis* by activating persulfate with Bordeaux mixture. The method involves generating sulfate and hydroxyl radicals through the activation of persulfate with Bordeaux mixture, while basic copper sulfate and calcium sulfate precipitate and synergistically flocculate and settle the pathogens and their residues. The inactivation effect of the Bordeaux mixture / PS system reaches over 99% within 5 minutes. The mechanism by which Bordeaux mixture activates persulfate to inactivate pathogenic microorganisms includes: the generation of SO4· ... - This method inactivates pathogenic microorganisms in the liquid phase using a multi-radical system with ·OH; and flocculates the pathogens and their residues through precipitation with basic copper sulfate and calcium sulfate. This method is simple to operate, low in cost, and provides stable results, making it promising and significant for practical applications. Attached Figure Description

[0018] Figure 1 This is the inactivation curve of Escherichia coli and Enterococcus faecalis in the Bordeaux mixture / PS system.

[0019] Figure 2 This describes the inactivation effect of the Bordeaux mixture / PS system when using different ratios of Bordeaux mixture.

[0020] Figure 3 The Bordeaux mixture / PS system is shown to be effective in inactivating four types of pathogens in medical wastewater.

[0021] Figure 4These are scanning electron microscope images of Escherichia coli after inactivation in the Bordeaux mixture / PS system. (a) shows the normal morphology of Escherichia coli before inactivation, and (b) shows the morphology of Escherichia coli after the membrane structure is destroyed after inactivation.

[0022] Figure 5 These are scanning electron microscope images of Escherichia coli precipitated with copper hydroxide, where (a) and (b) are images captured from different regions. Detailed Implementation

[0023] The specific implementation method of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0024] Example 1

[0025] Bordeaux mixture activates persulfate to inactivate E. coli

[0026] Escherichia coli was inoculated into an Erlenmeyer flask containing 50 mL of LB liquid medium. The flask was placed in a constant temperature shaking incubator at 37°C and 180 rpm for 12 h. After centrifugation, the supernatant was removed, and the precipitated E. coli was collected and placed in physiological saline. The reaction system was prepared as 10 mL, with persulfate concentration of 0.5-4 mmol / L and an initial colony concentration of 10⁻⁶. 7 The concentration of CFU / mL and the amount of Bordeaux mixture used were 5-50 μL. Centrifuge tubes were placed in a constant-temperature shaker at 25°C and 180 rpm. Samples were taken and plated at 0 min, 5 min, 15 min, 30 min, and 60 min. The inactivation efficiency increased with increasing Bordeaux mixture and persulfate concentrations. The optimal inactivation efficiency (7 log units) was achieved within 60 min when the Bordeaux mixture concentration was 10 μL and the persulfate concentration was 2.0 mmol / L. Figure 1 The inactivation curve is shown when Bordeaux mixture is used to activate persulfate to inactivate Escherichia coli. Figure 4 Scanning electron microscope image of Escherichia coli after inactivation in Bordeaux mixture / PS system. Figure 5 This is a scanning electron microscope image of the precipitate after the Bordeaux mixture-activated persulfate system reacts. It can be seen that the Bordeaux mixture-activated persulfate system can effectively disrupt the cell membrane structure of pathogenic microorganisms and allow for the settling of pathogenic microorganism residues through precipitation and flocculation. This system significantly improves the removal efficiency of pathogenic microorganisms from water bodies.

[0027] Example 2

[0028] Bordeaux mixture activates persulfate to inactivate Enterococcus faecalis

[0029] Enterococci were inoculated into Erlenmeyer flasks containing 50 mL of LB liquid medium. The flasks were placed in a constant temperature shaking incubator at 37°C and 180 rpm for 12 h. After centrifugation, the supernatant was removed, and the precipitated Enterococci were collected and placed in physiological saline. A 10 mL reaction system was prepared with persulfate at 0.5-4 mmol / L and an initial colony concentration of 10⁻⁶. 7 With CFU / mL and Bordeaux mixture volume of 5-50 μL, centrifuge tubes were placed in a constant-temperature shaker at 25°C and 180 rpm. Samples were taken and plated at 0 min, 5 min, 15 min, 30 min, and 60 min. The inactivation efficiency increased with increasing Bordeaux mixture and persulfate concentration. The optimal inactivation efficiency (7 log units) was achieved within 60 min when the Bordeaux mixture concentration was 10 μL and the persulfate concentration was 2.0 mmol / L. Figure 1 The inactivation curve is shown when Bordeaux mixture is used to activate persulfate to inactivate Escherichia coli.

[0030] Example 3

[0031] Inactivation effect of Bordeaux mixture / PS system with different Bordeaux mixture ratios

[0032] Three different formulations of Bordeaux mixture were used: equal volume, double volume, and multi-volume Bordeaux mixture. The reaction system consisted of 10 mL of Bordeaux mixture, with 10 μL of Bordeaux mixture added, and an initial colony concentration of 10. 7 CFU / mL, with the addition of 2.0 mmol / L persulfate, centrifuge tubes were placed in a constant-temperature shaker at 25℃ and 180 r / min. Samples were plated after 60 min. Results showed that Bordeaux mixtures of different ratios had good inactivation effects on *Escherichia coli* and *Enterococcus faecalis*. After 1 h of reaction, the inactivation effect on both *Escherichia coli* and *Enterococcus faecalis* was above 6 log units. Figure 2 As shown.

[0033] Example 4

[0034] Bordeaux mixture activates persulfate to inactivate various aquatic pathogens.

[0035] The reaction system used bacterial suspensions of Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa from real medical wastewater. The reaction volume was 10 mL, the Bordeaux mixture was added at 10 μL, and the initial colony concentration was 10. 7CFU / mL was added, and 2.0 mmol / L persulfate was added. The centrifuge tubes were placed in a constant temperature shaker at 25℃ and 180 r / min. Samples were taken and plated after 60 min. The results showed that Bordeaux mixture had an inactivating effect on various pathogenic microorganisms. After 1 h of reaction, the inactivation rate of Acinetobacter baumannii was 96.1%, the inactivation rate of Klebsiella pneumoniae was 91.5%, the inactivation rate of Staphylococcus aureus was 99.1%, and the inactivation rate of Pseudomonas aeruginosa was 94.6%. The inactivation effect was as follows. Figure 3 As shown.

Claims

1. A method for activating persulfate oxidation and inactivating pathogenic microorganisms in aquatic bodies using Bordeaux mixture, characterized in that, The steps are as follows: (1) Dissolve copper sulfate and calcium oxide in water in a certain proportion and stir to obtain Bordeaux mixture; (2) Bordeaux mixture and persulfate solution were added simultaneously to the water sample contaminated with pathogens to construct a Bordeaux mixture-activated persulfate system to effectively inactivate pathogens.

2. The method for activating persulfate oxidation and inactivating pathogenic microorganisms in water bodies using Bordeaux mixture according to claim 1, characterized in that, The Bordeaux mixture mentioned is any one of equal volume Bordeaux mixture, double volume Bordeaux mixture, or multi-volume Bordeaux mixture.

3. The method for activating persulfate oxidation and inactivating pathogenic microorganisms in water bodies using Bordeaux mixture according to claim 2, characterized in that, The mass ratio of the double-volume Bordeaux mixture is CuSO4:CaO:H2O = 1:2:

200.

4. The method for activating persulfate oxidation and inactivating pathogenic microorganisms in water bodies using Bordeaux mixture according to claim 1, characterized in that, The pathogen-contaminated water sample was 10. 7 For water samples contaminated with pathogenic microorganisms at CFU / mL, Escherichia coli and Enterococcus faecalis were used as targets for inactivation.

5. The method for activating persulfate oxidation and inactivating pathogenic microorganisms in water bodies using Bordeaux mixture according to claim 1, characterized in that, The persulfate mentioned is any one of sodium persulfate, potassium persulfate, ammonium persulfate, and magnesium persulfate, and its addition amount is 0.5-4 mmol / L.

6. The method for activating persulfate oxidation and inactivating pathogenic microorganisms in water bodies using Bordeaux mixture according to claim 1, characterized in that, The amount of Bordeaux mixture added is 0.05 wt.%-0.5 wt.%.

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