Novel treatment method for degrading typical antibiotic fluoroquinolones in water

Abstract

The invention discloses a novel treatment method for degrading typical antibiotic fluoroquinolones in water. Fluoroquinolone drugs (FQs) are artificially synthesized antibiotic drugs which are widely applied to clinic. In numerous FQs antibiotics, ciprofloxacin is a typical drug. Therefore, according to the project, the common fluoroquinolone antibiotic ciprofloxacin is selected as a research object, a method for degrading the fluoroquinolone antibiotics in the wastewater by an electrochemical oxidation method is discussed, and the influence of different electrolyte concentrations, pH values, degradation time, current density, electrolysis temperature and other electrolysis conditions on the removal effect is analyzed; a new thought is provided for treatment of the antibiotics in the wastewater.

Description

TECHNICAL FIELD

[0001] The present application relates to a new type of degradation of typical antibiotics in water fluoroquinolones (FQs) treatment method, belongs to water treatment technical field. BACKGROUND

[0002] Fluoroquinolones (FQs) is a kind of widely used in clinical artificial synthetic antibiotic drugs. Among the many FQs antibiotics, ciprofloxacin is a typical and more widely used pollutant. Due to its broad-spectrum antibacterial activity, good bactericidal effect and other characteristics, it has attracted high attention and extensive concern of international academic circles. The detection amount of ciprofloxacin in water body and soil environment is relatively high. At present, relevant research shows that many rivers and sewage treatment plants at home and abroad have high content of ciprofloxacin. The high content of ciprofloxacin and its potential harm to human health and ecology, how to effectively remove ciprofloxacin and ensure the safety of drinking water has gradually become a research hotspot.

[0003] At present, the degradation process of ciprofloxacin includes direct photolysis, UV / H2O2, Fenton, chlorination, etc. UV / H2O2 process is widely used in the removal of refractory organic matter, and the removal of antibiotics shows good performance. Studies have shown that the process of UV / H2O2 degradation of FQs conforms to the pseudo first-order kinetic model, and under the optimal conditions, a very high removal rate can be achieved. However, H2O2 is difficult to transport, store and apply in practical engineering. The initial stage of Fenton method for oxidizing degradation of ciprofloxacin is very effective, but it soon generates refractory metabolites, increasing the toxicity of wastewater. Therefore, there is an urgent need for a method that can efficiently degrade typical fluoroquinolone pollutants in water. SUMMARY

[0004] In view of the above defects or deficiencies of the prior art, the present application provides a new type of degradation of typical antibiotics in water fluoroquinolones (FQs) treatment method, to solve the problems of raw materials difficult to transport, store and effectively solve the water pollutants in the existing degradation process, and generate other toxic substances in the process of degrading ciprofloxacin.

[0005] In order to solve the problems existing in the existing ciprofloxacin degradation process, the present application adopts the following experimental scheme: Experimental 1: Explore the experimental setting of different concentrations of sodium chloride on antibiotic degradation 500mL of ciprofloxacin aqueous solution with an initial concentration of 2 μg / mL prepared with phosphate buffer solution (disodium hydrogen phosphate and sodium dihydrogen phosphate) is placed in an electrolytic cell containing a magnetic rotor, 1, 2, 5, 8, and 10 mmol of electrolyte NaCl is added respectively, and electrolysis experiments are carried out under the conditions of setting the experimental temperature and the pH of the solution. Sampling is performed at intervals to monitor and determine the optimal sodium chloride concentration for antibiotic degradation.

[0006] Implementation of Experiment 2: Experimental setup for exploring the effect of different pH conditions on antibiotic degradation 500ml of ciprofloxacin aqueous solution with a concentration of 2 μg / mL is added to the electrolytic cell, and the optimal dosage determined in Experiment 1 is used for the concentration of electrolyte NaCl. Different pH conditions are set, i.e. the control group, and the electrolytic cell is operated. Sampling is performed at intervals to monitor and determine the optimal pH condition for antibiotic degradation.

[0007] Implementation of Experiment 3: Experimental setup for exploring the effect of different temperature conditions on antibiotic degradation 500ml of ciprofloxacin aqueous solution with a concentration of 2 μg / mL is added to the electrolytic cell, and the optimal dosage determined in the previous section is used for the concentration of electrolyte NaCl. The optimal pH condition determined in the previous section is used for the pH group, and different reaction temperatures are set, i.e. 10℃, 15℃, 25℃, 35℃, and 40℃. The electrolytic cell is operated, and sampling is performed at intervals to monitor and determine the optimal temperature condition for antibiotic degradation.

[0008] Implementation of Experiment 4: Experimental setup for exploring the effect of different current density conditions on antibiotic degradation 500ml of ciprofloxacin aqueous solution with a concentration of 2 μg / mL is added to the electrolytic cell, and the optimal dosage determined in the previous section is used for the concentration of electrolyte NaCl. The optimal pH condition determined in the previous section is used for the pH group, and the optimal temperature for degrading ciprofloxacin determined in the previous section is used for the temperature. Different current densities are set, i.e. 3.0mA· cm -2 , 3.5mA· cm -2 , 4.0mA·cm -2 , 4.5mA·cm -2 , and 5.0mA· cm -2 The electrolytic cell is operated under the conditions of current density of 3.0mA· cm -2 , 3.5mA· cm -2 , 4.0mA·cm -2 , 4.5mA·cm -2 , and 5.0mA· cm -2 , and sampling is performed at intervals to monitor and determine the optimal current density condition.

[0009] Implementation of Experiment 5: Exploring the effect of multi-factor condition changes on the degradation of ciprofloxacin In order to study the degradation effect of electrolytic sodium chloride on the degradation of ciprofloxacin, considering the concentration of sodium chloride, pH, current density and degradation temperature, the degradation effect of the electrolytic cell under different electrolysis conditions such as sodium chloride concentration, pH, current density and degradation temperature at different reaction times (0, 1, 3, 5, 10, 15 min) is explored, the influence law of sodium chloride concentration, pH, current density and degradation temperature on the degradation effect is analyzed, and the best degradation condition of fluoroquinolone / ciprofloxacin is determined. BRIEF DESCRIPTION OF DRAWINGS

[0010] In order to more clearly illustrate the specific embodiments of the present application and the technical solutions in the present application, the drawings needed in the specific embodiments or prior art description will be briefly introduced as follows.

[0011] Figure 1 Electrolysis experimental device diagram Figure 2 Effect of different sodium chloride concentrations on antibiotic degradation in experiment 1 Figure 3 Effect of different pH on antibiotic degradation in experiment 2 Figure 4 Effect of different temperature conditions on antibiotic degradation in experiment 3 Figure 5 Effect of different current densities on antibiotic degradation in experiment 4 Figure 6 Effect of multi-factor condition change on antibiotic degradation in experiment 5 DETAILED DESCRIPTION

[0012] The specific embodiments of the present application will be described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0013] The present application will be described in detail below with reference to examples.

[0014] Experiment 1: Experimental setup to explore the effect of different sodium chloride concentrations on antibiotic degradation A 500 mL initial concentration of 2 μg / mL ciprofloxacin aqueous solution prepared with phosphate buffer solution (disodium hydrogen phosphate and sodium dihydrogen phosphate) was placed in an electrolytic cell containing a magnetic rotor, 1, 2, 5, 8 and 10 mmol of electrolyte NaCl were added respectively, the electrolytic cell was operated and the pH value was adjusted to maintain at 7.0-7.2, 1 mL sample was taken at 0, 1, 3, 5, 10 and 15 min respectively, the reaction was terminated with excess sodium thiosulfate, mixed well, then filtered through a 0.45 μm glass fiber membrane, and the sample was placed in a liquid chromatography sample bottle for low temperature storage before testing. Three parallel experiments were conducted to determine the optimal dosage of electrolyte.

[0015] Experiment 2: Experimental setup to investigate the effect of different pH conditions on antibiotic degradation 500 ml of ciprofloxacin aqueous solution with a concentration of 2 μg / mL was added into the electrolytic cell, and the electrolyte NaCl concentration was the optimal dosage determined in the previous section. Different pH conditions were set, namely the control group, the experimental group with pH value of 5.8-6.0, the experimental group with pH value of 6.8-7.0, the experimental group with pH value of 7.0-7.2, and the experimental group with pH value of 7.8-8.0. The experimental groups aimed to investigate the effect of pH close to pKa1 and pKa2 on ciprofloxacin degradation under weak acid and weak base conditions with pH of 5.8-8.0. The initial pH of the control group was 7.0, and the pH value was not controlled during the electrolysis process. The pH value change was recorded synchronously. The pH value of the experimental group with pH value of 5.8-6.0 was controlled between 5.8 and 6.0 during the electrolysis process. The pH value of the experimental group with pH value of 6.8-7.0 was controlled between 6.8 and 7.0 during the electrolysis process. The pH value of the experimental group with pH value of 7.0-7.2 was controlled between 7.0 and 7.2 during the electrolysis process. The pH value of the experimental group with pH value of 7.8-8.0 was controlled between 7.8 and 8.0 during the electrolysis process. The electrolytic cell was operated, and samples were taken at 0, 1, 3, 5, 10, and 15 min. The reaction was terminated with excess sodium thiosulfate, mixed well, filtered through a 0.45 μm glass fiber membrane, and three parallel experiments were conducted. Antibiotic concentration and TOC analysis were performed, and high-performance liquid chromatography and liquid chromatography-mass spectrometry analysis were conducted for the optimal pH condition group.

[0016] Experiment 3: Experimental setup to investigate the effect of different temperature conditions on antibiotic degradation 500 ml of ciprofloxacin aqueous solution with a concentration of 2 μg / mL was added into the electrolytic cell, and the electrolyte NaCl concentration was the optimal dosage determined in the previous section. The pH was the optimal pH condition group determined in the previous section, and different reaction temperatures were set, namely 10℃, 15℃, 25℃, 35℃, and 40℃. The electrolytic cell was operated at 10℃, 15℃, 25℃, 35℃, and 40℃, and samples were taken at 0, 1, 3, 5, 10, and 15 min. The reaction was terminated with excess sodium thiosulfate, mixed well, filtered through a 0.45 μm glass fiber membrane, and three parallel experiments were conducted to determine the optimal temperature for degrading ciprofloxacin.

[0017] Experiment 4: Experimental setup to investigate the effect of different current density conditions on antibiotic degradation 500 ml of ciprofloxacin aqueous solution with a concentration of 2 μg / mL was added into the electrolytic cell, and the electrolyte NaCl concentration was the optimal dosage determined in the previous section. The pH was the optimal pH condition group determined in the previous section, and the temperature was the optimal temperature for degrading ciprofloxacin determined in the previous section. Different current densities were set, namely 3.0 mA· cm -2, 3.5mA· cm -2 , 4.0mA· cm -2 , 4.5mA·cm -2 , 5.0mA·cm -2 respectively under the current density of 3.0mA· cm -2 , 3.5mA· cm -2 , 4.0mA·cm -2 , 4.5mA·cm -2 , 5.0mA·cm -2 Under the condition of electrolytic cell running at current density of 3.0mA· cm

[0018] Experiment 5: Explore the effect of multi-factor conditions on the degradation of ciprofloxacin In order to study the degradation effect of electrolytic sodium chloride on ciprofloxacin, considering the concentration of sodium chloride, pH, current density, degradation temperature, the degradation effect of different electrolytic conditions such as concentration of sodium chloride, pH, current density, degradation temperature of electrolytic cell at different reaction time (0, 1, 3, 5, 10, 15min) was explored.

[0019] In order to reduce the number of experiments, 4-factor 3-level orthogonal experiment was designed.

[0020] The concentration of electrolyte has a certain influence on the efficiency of degrading ciprofloxacin, and the three levels of sodium chloride concentration are selected as 2, 5, and 8mM. Under weak acid and weak base conditions, the degradation effect of ciprofloxacin is different, and the pH value is selected as 5.8-6.0, 7.0-7.2, and 7.8-8.0. The current density is selected as 3.5mA· cm -2 , 4.0mA· cm -2 , 4.5mA· cm -2 three levels, and the temperature is selected as 15℃, 25℃, and 35℃.

[0021] The factor level table and orthogonal experiment scheme are shown in Table 1 and Table 2.

[0022] Table 1 Factor level table Temperature A (°C) pH B Sodium chloride concentration C (mmol / L) Current density D (mA-cm-2) 15 5.8～6.0 2 3.5 25 7.0～7.2 5 4.0 35 7.8～8.0 8 4.5 Table 2 Orthogonal experiment scheme Orthogonal group Temperature A / °C pH B Current density C / mA-cm-2 Sodium chloride concentration D / mmol-L-1 ZJ-1 1(15) 1(5.8～6.0) 1(3.5) 1(2.0) ZJ-2 1(15) 2(7.0～7.2) 2(4.0) 2(5.0) ZJ-3 1(15) 3(7.8～8.0) 3(4.5) 3(8.0) ZJ-4 2(25) 1(5.8～6.0) 2(4.0) 3(8.0) ZJ-5 2(25) 2(7.0～7.2) 3(4.5) 1(2.0) ZJ-6 2(25) 3(7.8～8.0) 1(3.5) 2(5.0) ZJ-7 3(35) 1(5.8～6.0) 3(4.5) 2(5.0) ZJ-8 3(35) 2(7.0～7.2) 1(3.5) 3(8.0) ZJ-9 3(35) 3(7.8～8.0) 2(4.0) 1(2.0) Nine groups of orthogonal experiments were carried out, and each group was sampled at 0, 1, 3, 5, 10, 15 min, and the reaction was terminated with excess sodium thiosulfate, mixed well, filtered through a 0.45 μm glass fiber membrane, and then placed in a liquid chromatography sample bottle for low-temperature storage before testing.

[0023] Analysis method: The ciprofloxacin concentration was determined by high performance liquid chromatography, and the determination conditions were as follows: the chromatographic column was ZORBAX Extend-C18 column (250 mm x 4.6 mm, 5 μm), the mobile phase was a solution of chromatographic pure acetonitrile and water (3% acetic acid) with a volume ratio of 25%:75, the injection amount was 10 μL, and the flow rate was set to 1 mL / min; the column temperature was 40°C, the detector was a fluorescence (FLU) detector, and the absorption and emission wavelengths were 278 nm and 450 nm, respectively.

[0024] The instrument running time was set to 4.50 min when detecting ciprofloxacin. The retention time of the sample was used for qualitative analysis, and the peak area was used for quantitative analysis. The standard curve of the target substance was obtained by linear regression fitting of the horizontal coordinate of the sample concentration and the vertical coordinate of the chromatographic peak area, and this standard curve was used as the basis for calculating the concentration of the target pollutant.

[0025] The products in the antibiotic wastewater were detected by high performance liquid chromatography-mass spectrometry (Agilent 1260, Agilent Q-TOF) combined technology, and the conditions were as follows: the chromatographic column was InertSustain C18 column (150 mm x 4.6 mm, 5 μm), the mobile phase A was acetonitrile, the mobile phase B was ultrapure water containing 0.1% formic acid, the flow rate was 0.3 mL / min, the column temperature was 40°C, and the injection amount was 20 μL.

[0026] The gradient elution program was as follows: 90% of mobile phase B was maintained for 1 min, the mobile phase B was reduced from 90% to 10% within 19 min, the mobile phase B was increased from 10% to 90% within 4 min, and 90% of the mobile phase B was maintained for 10 min.

Claims

1. A novel method for treating water containing fluoroquinolone antibiotics (FQs), characterized in that: Typical antibiotics, fluoroquinolones (FQs), were treated in water by electrolysis of NaCl under specific electrolyte concentration, pH value, degradation time, current density, and electrolysis temperature conditions.

2. The novel method for treating water containing fluoroquinolone antibiotics (FQs) according to claim 1, characterized in that: This experiment selected ciprofloxacin, a commonly used fluoroquinolone antibiotic, as the research object to study the electrochemical oxidation method for degrading fluoroquinolone antibiotics in wastewater.

3. The method according to claim 1, characterized in that: The reagents used in the experiment were ciprofloxacin, sodium chloride, disodium hydrogen phosphate and sodium dihydrogen phosphate, acetonitrile, methanol, sodium thiosulfate, and ultrapure water.

4. The method according to claim 1, characterized in that: This experiment was conducted in a rectangular electrolytic cell with an effective volume of 500 ml, and the electrodes used were RuO2-IrO2-TiO2 / Ti electrodes.

5. The method according to claim 1, characterized in that: The operation of the electrolytic cell requires certain conditions, namely, adding 500 ml of 2 μg / mL ciprofloxacin aqueous solution to the electrolytic cell, stirring at a speed of (500±50) r / min, a distance of 4 cm between the anode plate and the cathode plate, and immersing the main body of the electrode plate in the solution.

6. The method according to claim 1, characterized in that: At room temperature (25 degrees Celsius), 30 ml of chromatographically pure acetic acid was measured using a 50 ml measuring cup and poured into a 1000 ml volumetric flask. The volume was adjusted to the required level with ultrapure water and a dropper, mixed well, filtered using an inorganic filter membrane, and sonicated for 3 minutes to obtain a 3% acetic acid aqueous solution.

7. The method according to claim 1, characterized in that: The preparation process of the 2 μg / ml ciprofloxacin solution required for the experiment is as follows: Weigh 51.02 g of 98% ciprofloxacin sample onto weighing paper using a 0.01% balance, pour it into a 50 ml volumetric flask, and dilute to volume with 3% acetic acid aqueous solution. Using a pipette, add 1 ml of the ciprofloxacin aqueous solution to a 500 ml volumetric flask, simultaneously adding a measured amount of sodium chloride sample and a certain proportion of sodium dihydrogen phosphate and disodium hydrogen phosphate to adjust the pH value. Dilute to 500 ml with experimental water (ultrapure water) to obtain the required ciprofloxacin solution for the experiment.

8. The electrochemical oxidation method according to claim 2, characterized in that: The electrochemical oxidative degradation of ciprofloxacin was carried out by electrolyzing a mixed solution of NaCl and ciprofloxacin under certain electrolyte concentration, pH value, degradation time, current density, and electrolysis temperature conditions.

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