Method for degrading antibiotics in wastewater based on chitosan aerogel

Abstract

The invention discloses a method for degrading antibiotics in wastewater based on chitosan aerogel. The method comprises the following steps: adding chitosan aerogel Co-PBA / CS and potassium hydrogen peroxymonosulfate into the antibiotic-containing wastewater, and degrading under stirring. The method provided by the invention has a ciprofloxacin degradation capability of 94.7%. In addition, the material also has excellent self-cleaning and photo-thermal conversion performance, and can realize surface cleaning. The multifunctional aerogel provides a new strategy for removing pollutants such as ciprofloxacin in a complex and severe water environment.

Description

Technical Field

[0001] This invention belongs to the field of antibiotic degradation technology, specifically relating to a method for degrading antibiotics in wastewater based on chitosan aerogel. Background Technology

[0002] In recent years, global environmental issues have increasingly become a focus of human concern, with water pollution receiving particular attention. The development of agriculture and the widespread use of pesticides have further burdened water resources. In particular, antibiotics discharged into agricultural wastewater complicate water systems and pose a significant threat to human health. Once antibiotic-containing wastewater enters the environment, it creates complex risks at both ecological and health levels: first, it directly produces low-concentration, long-term chronic toxicological effects on aquatic organisms; second, it induces and accelerates the generation and spread of antibiotic resistance genes (ARGs) and drug-resistant bacteria, forming a "drug resistance reservoir"; and third, through exposure in drinking water and the food chain, it disrupts the human microecology and increases the risk of infection treatment failure. Antibiotics have been listed as one of the first batch of key controlled new pollutants in my country, and their environmental and health risks exhibit cross-regional and cross-media transmission characteristics. Therefore, developing an effective method for antibiotic removal is essential. Summary of the Invention

[0003] To address the aforementioned technical problems, the present invention aims to provide a method for degrading antibiotics in wastewater based on chitosan aerogel, which has a high antibiotic removal efficiency.

[0004] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows: a method for degrading antibiotics in wastewater based on chitosan aerogel, the method being as follows: adding chitosan aerogel Co-PBA / CS and potassium persulfate to antibiotic-containing wastewater, and carrying out degradation under stirring.

[0005] Furthermore, the initial concentration of antibiotics in the wastewater was adjusted to 5 mg·L⁻¹. -1 -15mg·L -1 The pH value is 3-9.

[0006] Furthermore, the amount of chitosan aerogel Co-PBA / CS added is 0.2 mg / mL-1 mg / mL.

[0007] Further, potassium persulfate was added to a concentration of 1 mM-5 mM.

[0008] Furthermore, the antibiotic is ciprofloxacin.

[0009] Furthermore, the preparation method of the chitosan aerogel Co-PBA / CS includes the following steps:

[0010] 1) Cobalt acetate tetrahydrate and trisodium citrate dissolved in water to form solution A, and potassium ferricyanide dissolved in water to form solution B. After mixing and stirring solutions A and B, the mixture was allowed to stand to precipitate, centrifuged, washed and dried to obtain Co-PBA.

[0011] 2) Add Co-PBA to the chitosan aqueous solution, then add PVA solution, and stir continuously to obtain a homogeneous mixed solution; add acetic acid solution to the obtained mixed solution, then add glutaraldehyde solution dropwise, stir in a water bath at 55℃-65℃ for 1h-2h, and freeze dry to obtain Co-PBA / CS aerogel.

[0012] Further, in step 1), the volume ratio of solution A to solution B is 1:(1-2).

[0013] Further, in step 2), the mass ratio of chitosan:Co-PBA is (2-4):1.

[0014] Further, in step 2), the volume ratio of chitosan aqueous solution to PVA solution is (1.5-2.5):1.

[0015] The beneficial effects of this invention are:

[0016] 1. The method provided by this invention mainly degrades antibiotics by promoting PMS catalytic activation to generate free radicals that decompose ciprofloxacin into smaller molecules.

[0017] 2. The method provided by this invention enables Co-PBA / CS aerogel to degrade antibiotics, and it still has excellent degradation effect in different water environments.

[0018] 4. The method provided by this invention achieves a ciprofloxacin degradation rate of 94.7%. Furthermore, the Co-PBA / CS aerogel exhibits excellent photothermal conversion properties. This multifunctional aerogel provides a new strategy for removing ciprofloxacin from complex and harsh aquatic environments. Attached Figure Description

[0019] Figure 1 These are scanning electron microscope images of chitosan CS (a1, a2) and Co-PBA / CS aerogel (b1, b2).

[0020] Figure 2 The effects of catalyst dosage (a), PMS dosage (b), and pH (c) on the degradation of ciprofloxacin are shown.

[0021] Figure 3 The following are (a) the removal rate of ciprofloxacin in different reaction systems; (b) the effect of free radical scavengers on the degradation of ciprofloxacin; (c) the effect of different water bodies; and (d) the recyclability of the catalyst during degradation. Detailed Implementation

[0022] Example 1: Preparation of chitosan aerogel Co-PBA / CS

[0023] (I) Preparation method

[0024] 1) Preparation of chitosan (CS) aqueous solution:

[0025] Add 0.3g of chitosan (CS) to 10mL of deionized water and stir for 30min to form a homogeneous solution, thus obtaining an aqueous solution of chitosan (CS).

[0026] 2) Preparation of Co-PBA:

[0027] Solution A was prepared by dissolving 149 mg cobalt acetate tetrahydrate and 220 mg trisodium citrate in 40 mL of water. Solution B was prepared by dissolving 132 mg potassium ferricyanide in 60 mL of water. Solutions A and B were mixed and stirred, and then allowed to stand for 1 day to precipitate. The precipitate was then centrifuged, washed, and dried to obtain Co-PBA.

[0028] 3) Preparation of Co-PBA / CS aerogel

[0029] 0.1 g of Co-PBA was added to a chitosan (CS) aqueous solution, followed by 5 mL of 4 wt% polyvinyl alcohol (PVA) solution. The mixture was stirred for 1 h to form a homogeneous solution. 8 mL of acetic acid solution was added to the resulting solution, and the mixture was stirred until homogeneous. The solution was then placed in a 60°C water bath, and 0.8 mL of glutaraldehyde (GA) solution was added dropwise. After stirring for 2 h, a highly viscous solution was formed through vigorous stirring. The solution was transferred to a 2 cm × 2 cm × 2 cm cubic mold, frozen at -20°C for 12 h, freeze-dried at -80°C for 24 h, and then soaked in anhydrous ethanol for 24 h to remove residual acetic acid. Finally, the solution was dried to obtain Co-PBA / CS aerogel.

[0030] (ii) Characterization

[0031] like Figure 1 As shown, the original CS aerogel has a highly interconnected porous network ( Figure 2 a1); CS aerogel surface is smooth ( Figure 2 (a2). Co-PBA is well distributed within the aerogel framework, forming a rough and non-uniform surface. Figure 2 In b1), Co-PBA exhibits a cubic structure in the aerogel. Figure 2 (b2)

[0032] Example 2: A method for ciprofloxacin degradation based on chitosan aerogel Co-PBA / CS

[0033] Methods: The Co-PBA / CS aerogel prepared in Example 1 was added to an aqueous solution of ciprofloxacin. Adsorption / desorption equilibrium was established by stirring for 30 min. A certain amount of PMS was added. At fixed time intervals, 2 mL of the sample was taken out and filtered through a 0.22 μm nylon membrane. The absorbance was measured immediately using UV-Vis spectroscopy.

[0034] The degradation rate (η) is calculated using the following formula:

[0035]

[0036] In the formula, C0 (mg / L) is the initial concentration of ciprofloxacin; C t (mg / L) represents the concentration of ciprofloxacin in the solution after degradation.

[0037] (I) Effects of reaction parameters on the degradation of ciprofloxacin

[0038] To obtain optimal reaction conditions, the effects of catalyst dosage, PMS dosage, and pH on degradation performance were investigated.

[0039] 1. Effect of Co-PBA / CS dosage on the degradation performance of ciprofloxacin

[0040] Method: 2 mg, 4 mg, 6 mg, 8 mg, and 10 mg of aerogel Co-PBA / CS were added to 10 mL of 10 mg·L⁻¹ aerogel solution, respectively. -1 In a ciprofloxacin aqueous solution at pH 7, adsorption / desorption equilibrium was established by stirring for 30 min. PMS was then added to a concentration of 3 mM. At fixed time intervals, 2 mL samples were taken and filtered through a 0.22 μm nylon membrane. Absorbance was immediately measured using UV-Vis spectroscopy, and the degradation rate was calculated. Results are as follows: Figure 2 a.

[0041] from Figure 2 As can be seen from Figure a, the degradation rate of ciprofloxacin increases with the increase of aerogel dosage. This may be because the increase in catalyst dosage can provide more active sites to activate PMS. However, when the catalyst dosage continues to increase, the improvement in removal rate is not significant, which may be due to the limitation of PMS concentration. Therefore, in this invention, the amount of Co-PBA / CS added is preferably 0.2 mg / mL-1 mg / mL, more preferably 1 mg / mL.

[0042] 2. Effect of PMS dosage on the degradation performance of ciprofloxacin

[0043] Method: Add 10 mg of Co-PBA / CS aerogel to 10 mL of 10 mg·L⁻¹ aerogel. -1In a ciprofloxacin aqueous solution at pH 7, adsorption / desorption equilibrium was established by stirring for 30 min. PMS was then added to concentrations of 1 mM, 2 mM, 3 mM, 4 mM, and 5 mM, respectively. At fixed time intervals, 2 mL samples were taken each time and filtered through a 0.22 μm nylon membrane. Absorbance was immediately measured using UV-Vis spectroscopy, and the degradation rate was calculated. Results are as follows: Figure 2 b.

[0044] from Figure 2 As shown in Figure b, the degradation rate of ciprofloxacin initially increases and then decreases with increasing PMS dosage. Initially, the increase in PMS leads to the generation of additional ROS, thereby enhancing the degradation of ciprofloxacin. However, the limited active sites on the catalyst may subsequently restrict the activation of PMS to produce excessive HSO5. - Excessive HSO5 - It has the effect of scavenging free radicals and reducing SO4• - The amount of •OH available reduces the degradation rate. Therefore, the present invention preferably adds potassium persulfate to a concentration of 1 mM-5 mM, more preferably, potassium persulfate to a concentration of 3 mM.

[0045] 3. Effect of pH on the degradation performance of ciprofloxacin

[0046] Method: Add 10 mg of Co-PBA / CS aerogel to 10 mL of 10 mg·L⁻¹ aerogel. -1 In aqueous solutions of ciprofloxacin with pH values ​​of 3, 5, 7, and 9, adsorption / desorption equilibrium was established by stirring for 30 min. PMS was then added to a concentration of 3 mM. At fixed time intervals, 2 mL samples were taken and filtered through a 0.22 μm nylon membrane. Absorbance was immediately measured using UV-Vis spectroscopy, and the degradation rate was calculated. Results are as follows: Figure 2 c.

[0047] from Figure 2 As can be seen from Figure c, the degradation rate of ciprofloxacin first increases and then decreases with increasing pH. These data indicate that near-neutral or weakly acidic conditions are favorable for the catalytic degradation of ciprofloxacin. Preferably, the pH is adjusted to 3-9, more preferably to 7.

[0048] (ii) Degradation and recycling capacity of Co-PBA / CS

[0049] This study investigates the degradation and recycling capabilities of Co-PBA / CS aerogel for ciprofloxacin and assesses its feasibility for use in real-world environments.

[0050] 1. Effects of different catalytic systems on the degradation of ciprofloxacin

[0051] Methods: Different reaction systems (PMS only, a mixture of pure CS and PMS, a mixture of Co-PBA / CS and PMS, and Co-PBA / CS only) were added to 10 mL of 10 mg·L⁻¹ solution. -1 In a ciprofloxacin aqueous solution at pH 7, adsorption / desorption equilibrium was established by stirring for 30 min. At fixed time intervals, 2 mL samples were taken and filtered through a 0.22 μm nylon membrane. Absorbance was immediately measured using UV-Vis spectroscopy, and the degradation rate was calculated. Results are as follows: Figure 3 a.

[0052] like Figure 3 In this study, the introduction of the Co-PBA / CS catalyst into the system, in synergy with PMS, resulted in a ciprofloxacin degradation rate of 94.7%, significantly higher than other systems. This superior performance is attributed to the synergistic catalytic effect between the Co and Fe sites in Co-PBA / CS, which significantly enhances PMS activation, promotes free radical generation, and thus more effectively degrades ciprofloxacin.

[0053] 2. Effects of different quenchers on the degradation of ciprofloxacin

[0054] Methods: Different quenchers (blank, tert-butanol (TBA), methanol (MeOH), L-histidine (L-His), p-benzoquinone (P-BQ)) and the same Co-PBA / CS and PMS system were added to 10 mL of 10 mg·L⁻¹ -1 In a ciprofloxacin aqueous solution at pH 7, adsorption / desorption equilibrium was established by stirring for 30 min. At fixed time intervals, 2 mL samples were taken and filtered through a 0.22 μm nylon membrane. Absorbance was immediately measured using UV-Vis spectroscopy, and the degradation rate was calculated. Results are as follows: Figure 3 b.

[0055] like Figure 3 b, prove SO4• - •OH 1 O2 and O2• - Free radicals play a role in the degradation of ciprofloxacin, and calculations show that non-free radicals... 1 O2 and free radicals SO4• - It is the main reactive oxygen species involved in the degradation of ciprofloxacin.

[0056] 3. Effects of different water samples on the degradation of ciprofloxacin

[0057] Methods: Different water samples (tap water, lake water, and rainwater) were centrifuged and filtered through a membrane. The treated water was used as a solvent to prepare ciprofloxacin solution, which was then added to 10 mL of a Co-PBA / CS and PMS system at a concentration of 10 mg / L. -1 In a ciprofloxacin aqueous solution at pH 7, adsorption / desorption equilibrium was established by stirring for 30 min. At fixed time intervals, 2 mL samples were taken and filtered through a 0.22 μm nylon membrane. Absorbance was immediately measured using UV-Vis spectroscopy, and the degradation rate was calculated. Results are as follows: Figure 3 c.

[0058] like Figure 3 In the case of sample c, the degradation rate of ciprofloxacin decreased due to the presence of different pollutants in the three water samples, but the degradation efficiency was still above 80%, indicating that Co-PBA / CS has strong anti-interference ability and good application prospects.

[0059] 4. Cyclic Experiment

[0060] Method: The Co-PBA / CS and PMS system was added to 10 mL of 10 mg·L⁻¹ -1 In a ciprofloxacin aqueous solution at pH 7, adsorption / desorption equilibrium was established by stirring for 30 min. At fixed time intervals, 2 mL samples were taken and filtered through a 0.22 μm nylon membrane. Absorbance was immediately measured using UV-Vis spectroscopy to calculate the degradation rate. After the degradation experiment, the aerogel was washed with deionized water and ethanol, then dried in an oven for subsequent degradation experiments. Results are as follows: Figure 3 d.

[0061] like Figure 3 In the middle d, after 5 cycles, the Co-PBA / CS catalyst system still maintained a high degradation efficiency, which proves the high recyclability and reusability of the Co-PBA / CS catalyst.

[0062] (III) Degradation mechanism of Co-PBA / CS

[0063] Its degradation of ciprofloxacin occurs via a free radical pathway (•OH, SO4•). - and O2• - ) and non-free radical pathways ( 1 O2). In the free radical pathway, when the Co-PBA / CS system activates PMS, the main active sites exist primarily in the form of Co(II) and Fe(III) before the reaction, interacting with HSO5• on the catalyst surface. - After the reaction, it is converted into Co(III) and Fe(II), producing sulfate free radicals (SO4•). -Subsequently, SO4• - Free radicals react with H₂O to generate hydroxyl radicals (•OH). Dissolved oxygen in water can utilize electrons provided by the system to form superoxide radicals (O₂•OH). - In the non-radical pathway, it can be achieved through O2• - Reaction with •OH in solution and SO5• - Self-reaction generation 1 O2. Various reports have found O2• - The restructuring is the cause 1 The reason for O2 formation. Finally, in the presence of various active substances, ciprofloxacin is degraded into water and carbon dioxide.

Claims

1. A method for degrading antibiotics in wastewater based on chitosan aerogel, characterized in that, The method is as follows: chitosan aerogel Co-PBA / CS and potassium persulfate are added to the antibiotic-containing wastewater, and degradation is carried out under stirring.

2. The method for degrading antibiotics in wastewater based on chitosan aerogel according to claim 1, characterized in that, The initial concentration of antibiotics in the wastewater was adjusted to 5 mg·L. -1 -15mg·L -1 The pH value is 3-9.

3. The method for degrading antibiotics in wastewater based on chitosan aerogel according to claim 1, characterized in that, The amount of chitosan aerogel Co-PBA / CS added is 0.2 mg / mL-1 mg / mL.

4. The method for degrading antibiotics in wastewater based on chitosan aerogel according to claim 1, characterized in that, Add potassium persulfate to a concentration of 1 mM-5 mM.

5. A method for degrading antibiotics in wastewater based on chitosan aerogel according to any one of claims 1-4, characterized in that, The antibiotic in question is ciprofloxacin.

6. A method for degrading antibiotics in wastewater based on chitosan aerogel according to any one of claims 1-4, characterized in that, The chitosan aerogel Co-PBA / CS is prepared by the following steps: 1) Cobalt acetate tetrahydrate and trisodium citrate dissolved in water to form solution A, and potassium ferricyanide dissolved in water to form solution B. After mixing and stirring solutions A and B, the mixture was allowed to stand to precipitate, centrifuged, washed and dried to obtain Co-PBA. 2) Add Co-PBA to the chitosan aqueous solution, then add PVA solution, and stir continuously to obtain a homogeneous mixed solution; add acetic acid solution to the obtained mixed solution, then add glutaraldehyde solution dropwise, stir in a water bath at 55℃-65℃ for 1h-2h, and freeze dry to obtain Co-PBA / CS aerogel.

7. The method for degrading antibiotics in wastewater based on chitosan aerogel according to claim 6, characterized in that, In step 1), the volume ratio of solution A to solution B is 1:(1-2).

8. The method for degrading antibiotics in wastewater based on chitosan aerogel according to claim 6, characterized in that, In step 2), the mass ratio of chitosan:Co-PBA is (2-4):

1.

9. The method for degrading antibiotics in wastewater based on chitosan aerogel according to claim 6, characterized in that, In step 2), the volume ratio of chitosan aqueous solution to PVA solution is (1.5-2.5):1.

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