Method for removing antibiotics by using a mixture of goethite and pyrite and application thereof

Abstract

The application discloses a method for removing antibiotics by mixing goethite and pyrite and application thereof, and comprises the following steps: (1) crushing the goethite and the pyrite; (2) preparing antibiotic wastewater; (3) mixing and reacting the goethite and the pyrite with the antibiotic wastewater in different proportions; and applying the method to rainwater treatment. The goethite and the pyrite are mixed to degrade the antibiotics in water, have wide pH adaptability, mild reaction environment, low cost, high removal efficiency, realize waste treatment by waste, and have important significance for the environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wastewater treatment, in particular to a method for removing antibiotics by using goethite and pyrite and application thereof. BACKGROUND

[0002] Antibiotics are mainly secondary metabolites or synthetic analogues produced by bacteria, molds or other microorganisms, which can inhibit or kill pathogenic microorganisms. At present, antibiotics have been widely used in the treatment of human and animal diseases. Due to the discharge of pharmaceutical industry wastewater, the discharge of medical antibiotics and the overuse in livestock breeding industry, there are certain concentrations of antibiotics remaining in surface water and groundwater. Long-term residual antibiotics can cause serious harm to human health and aquatic ecosystems. The contaminated surface water and groundwater flow into lakes, and after evaporation, rainwater is formed, which contains residual antibiotic pollutants. Even clean and uncontaminated rainwater falls to the ground, it will also converge with antibiotic-contaminated surface water and groundwater to form contaminated water.

[0003] At present, the methods for removing antibiotics include physical method, biological method and chemical method. The physical method mainly uses adsorption, precipitation and membrane separation technology, but only transfers and concentrates the antibiotics from water to a new phase, which is easy to cause secondary pollution to the environment. The biological method uses the enzyme catalytic system of microorganisms to reduce the nitro group in antibiotics to less toxic amino compounds. Common methods include activated sludge method, contact oxidation method and membrane reaction method. However, the microbial method is only suitable for low-concentration antibiotic solutions. The chemical method refers to the oxidation or reduction method for removing antibiotics. By using chemical reagents to gain or lose electrons, antibiotics are converted into low-toxic or harmless substances, which has high efficiency and low cost, and is widely used in the removal of antibiotic drugs.

[0004] Iron-based metal catalysts have attracted widespread attention due to their excellent catalytic performance and environmental friendliness. However, a large number of iron-based metal catalysts are prepared by synthesis, which has high cost and is easy to pollute the environment. Goethite is formed by weathering of pyrite, magnetite and other iron ores, and is a tailing in the environment. Pyrite is the most abundant iron sulfide on earth, and its main component is FeS2, usually in the form of cubic and octahedral crystals. Due to the high content of sulfur in pyrite, it is often used as a raw material for the preparation of sulfur and sulfuric acid. If the two waste minerals, pyrite and goethite, can be utilized, a low-cost composite material for removing antibiotics in the environment can be developed, realizing "waste treatment with waste", which has important significance for the environment. SUMMARY

[0005] In order to solve the problems of the prior art, the present application aims to provide a method for removing antibiotics by mixing goethite and pyrite and application thereof, which removes antibiotics in wastewater by mixing goethite and pyrite and applies it to the treatment of antibiotics in rainwater.

[0006] In order to achieve the above-mentioned purpose, the present application adopts the following technical scheme:

[0007] A method for removing antibiotics by mixing goethite and pyrite comprises the following steps:

[0008] (1) crushing pyrite and goethite;

[0009] (2) preparing antibiotic wastewater;

[0010] (3) mixing pyrite and goethite with antibiotic wastewater in different proportions and reacting.

[0011] In the step (1), the particle size of pyrite is 100-400 mesh, and the particle size of goethite is 100-400 mesh.

[0012] In the step (2), the antibiotic wastewater contains metronidazole or chloramphenicol, the pH value of the antibiotic wastewater is 6-10, and the concentration of metronidazole or chloramphenicol is 5-30 ppm.

[0013] In the step (2), the antibiotic wastewater is a mixture of buffer solution with different pH values and metronidazole or chloramphenicol, the antibiotic wastewater with pH 6 is a mixture of acetic acid-sodium acetate buffer solution and metronidazole or chloramphenicol, the antibiotic wastewater with pH 7 is a mixture of MES buffer solution and metronidazole or chloramphenicol, the antibiotic wastewater with pH 8 or 9 is a mixture of Tris-HCl buffer solution and metronidazole or chloramphenicol, and the antibiotic wastewater with pH 10 is a mixture of glycine buffer solution and metronidazole or chloramphenicol.

[0014] In the step (3), the mass ratio of pyrite to goethite is (1 / 3-3):1.

[0015] The method for removing antibiotics by mixing goethite and pyrite is applied to the treatment of rainwater polluted by antibiotics.

[0016] The present application has the following beneficial effects:

[0017] 1. Pyrite is a kind of aged iron-based mineral containing sulfur, often distributed in soil and sediment as tailings, with a standard reduction electrode potential of +0.35 V, having certain reducibility. Goethite is a kind of particle structure with stable chemical properties and large specific surface area, which can stably exist in acid soil. Pyrite can reduce Fe(III) in goethite to Fe(II), and the dissolution amount of Fe(II) in the system increases, and through the oxidation of substances such as metronidazole and chloramphenicol in the Fe(II) reduction system, waste is treated with waste.

[0018] 2. The system can efficiently remove metronidazole and chloramphenicol in the pH range of 6-10, has wide pH adaptability, and can be widely applied to the treatment of antibiotics in rainwater.

[0019] 3. Using natural pyrite and goethite as raw materials, no pretreatment is needed, and the antibiotics wastewater can be directly added for removal, and the reaction can be carried out at room temperature, the reaction environment is mild, the cost is low, and the removal efficiency is high.

[0020] 4. Under the conditions of pH 8-10, the removal of metronidazole and chloramphenicol by goethite and pyrite is very fast, and since the sulfate type green rust is generated at pH 8 and 9, and magnetite is generated at pH 10, the antibiotics can be efficiently removed.

[0021] 5. In the process of cooperative removal of antibiotics by goethite and pyrite, the pH in the system will decrease, and under acidic conditions, the cooperative removal effect is weak, but the introduction of a buffer system can maintain the reaction system within a certain pH range, thereby improving the removal efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The curve graph of removing 10 ppm metronidazole by Example 1 within 360 min;

[0023] Figure 2 The curve graph of removing 10 ppm metronidazole by Example 2 within 360 min;

[0024] Figure 3 The curve graph of removing 10 ppm metronidazole by Example 3 within 360 min;

[0025] Figure 4 The curve graph of removing 10 ppm metronidazole by Example 4 within 360 min;

[0026] Figure 5 The curve graph of removing 10 ppm metronidazole by Example 5 within 360 min;

[0027] Figure 6 The curve graph of removing 10 ppm metronidazole by Example 5 within 10 days;

[0028] Figure 7 Graph of removal of 20 ppm metronidazole over 360 min for Example 6;

[0029] Figure 8 Graph of removal of 20 ppm metronidazole over 360 min for Example 7;

[0030] Figure 9 Graph of removal of 20 ppm metronidazole over 360 min for Example 8;

[0031] Figure 10 Graph of removal of 20 ppm metronidazole over 360 min for Example 9;

[0032] Figure 11 Graph of removal of 30 ppm metronidazole over 360 min for Example 10;

[0033] Figure 12 Graph of removal of 30 ppm metronidazole over 360 min for Example 11;

[0034] Figure 13 Graph of removal of 30 ppm metronidazole over 360 min for Example 12;

[0035] Figure 14 Graph of removal of 30 ppm metronidazole over 360 min for Example 13;

[0036] Figure 15 Graph of removal of 20 ppm chloramphenicol over 360 min at pH 6 for Example 14;

[0037] Figure 16 Graph of removal of 20 ppm chloramphenicol over 360 min at pH 7 for Example 14;

[0038] Figure 17 Graph of removal of 20 ppm chloramphenicol over 360 min at pH 8 for Example 14;

[0039] Figure 18 Graph of removal of 20 ppm chloramphenicol over 360 min at pH 9 for Example 14;

[0040] Figure 19 Graph of removal of 20 ppm chloramphenicol over 360 min at pH 10 for Example 14;

[0041] Figure 20Scanning electron microscope image of the minerals after removal of chloramphenicol by 0.45 g of natural pyrite + 0.15 g of goethite for the pH 9 condition in Example 14;

[0042] Figure 21 Graph of removal of 20 ppm metronidazole within 360 min at pH 6 for Comparative Example 3;

[0043] Figure 22 Graph of removal of 20 ppm metronidazole within 360 min at pH 7 for Comparative Example 3;

[0044] Figure 23 Graph of removal of 20 ppm metronidazole within 360 min at pH 8 for Comparative Example 3;

[0045] Figure 24 Graph of removal of 20 ppm metronidazole within 360 min at pH 9 for Comparative Example 3. DETAILED DESCRIPTION

[0046] The application will be further described below in conjunction with the drawings and specific embodiments:

[0047] Example 1

[0048] (1) Take natural pyrite (purchased from Guangzhou Huadong Tangtang Crafts Factory), after crushing and sieving, obtain 100 mesh natural pyrite powder, and then use; after sieving, obtain 100 mesh goethite, and then use.

[0049] (2) Take 4 250 mL reaction bottles, add 150 mL of acetic acid-sodium acetate buffer solution to each reaction bottle, add 0.01 g of metronidazole powder, shake well, and adjust the pH of the mixture to 6 to obtain artificial synthetic metronidazole wastewater with a pH of 6 and a concentration of 10 ppm.

[0050] (3) Add 0.3 g of natural pyrite (reaction bottle contains 2 g / L pyrite (Pyrite)), 0.15 g of natural pyrite + 0.15 g of goethite (reaction bottle contains 1 g / L pyrite (Pyrite) + 1 g / L goethite (Goethite)), 0.3 g of natural pyrite + 0.15 g of goethite (reaction bottle contains 2 g / L pyrite (Pyrite) + 1 g / L goethite (Goethite)), and 0.45 g of natural pyrite + 0.15 g of goethite (reaction bottle contains 3 g / L pyrite (Pyrite) + 1 g / L goethite (Goethite)) to each reaction bottle, respectively, and react in a shaker at a speed of 300 r / min and a temperature of 25°C for 360 min. After the reaction is completed, the concentration of residual metronidazole is determined by high performance liquid chromatography.

[0051] Example 2

[0052] (1) Take natural pyrite, after crushing and sieving, get 100 mesh natural pyrite powder for later use; after sieving, get 100 mesh goethite for later use.

[0053] (2) Take 4 250 mL reaction bottles, add 150 mL of MES buffer solution (morpholine ethanesulfonic acid buffer) to each reaction bottle, add 0.01 g of metronidazole powder, shake well, adjust the pH of the mixture to 7, get artificial synthetic metronidazole wastewater with pH 7 and concentration of 10 ppm.

[0054] (3) Add 0.3 g of natural pyrite (reaction bottle contains 2 g / L Pyrite), 0.15 g of natural pyrite + 0.15 g of goethite (reaction bottle contains 1 g / L Pyrite + 1 g / L Goethite), 0.3 g of natural pyrite + 0.15 g of goethite (reaction bottle contains 2 g / L Pyrite + 1 g / L Goethite), 0.45 g of natural pyrite + 0.15 g of goethite (reaction bottle contains 3 g / L Pyrite + 1 g / L Goethite) to each reaction bottle respectively, react in a shaker with rotation speed of 300 r / min and temperature of 25℃ for 360 min. After reaction, the concentration of residual metronidazole is determined by high performance liquid chromatography.

[0055] Example 3

[0056] (1) Take natural pyrite, after crushing and sieving, get 100 mesh natural pyrite powder for later use; after sieving, get 100 mesh goethite for later use.

[0057] (2) Take 4 250 mL reaction bottles, add 150 mL of Tris-HCl buffer solution (tris(hydroxymethyl) aminomethane hydrochloride buffer) to each reaction bottle, add 0.01 g of metronidazole powder, shake well, adjust the pH of the mixture to 8, get artificial synthetic metronidazole wastewater with pH 8 and concentration of 10 ppm.

[0058] (3) 0.3 g of natural pyrite (2 g / L Pyrite in the reaction bottle), 0.15 g of natural pyrite + 0.15 g of goethite (1 g / L Pyrite + 1 g / L Goethite in the reaction bottle), 0.3 g of natural pyrite + 0.15 g of goethite (2 g / L Pyrite + 1 g / L Goethite in the reaction bottle), and 0.45 g of natural pyrite + 0.15 g of goethite (3 g / L Pyrite + 1 g / L Goethite in the reaction bottle) were added to each reaction bottle, respectively, and reacted in a shaker at 300 r / min and 25°C for 360 min. After the reaction, the residual metronidazole concentration was determined by high performance liquid chromatography.

[0059] Example 4

[0060] (1) Natural pyrite was crushed and sieved to obtain 100-mesh natural pyrite powder, which was used as is. Goethite was sieved to obtain 100-mesh goethite, which was used as is.

[0061] (2) Four 250-mL reaction bottles were prepared, and 150 mL of Tris-HCl buffer solution was added to each reaction bottle. 0.01 g of metronidazole powder was added to each reaction bottle, and the mixture was shaken and adjusted to pH 9 to obtain an artificial metronidazole wastewater with a concentration of 10 ppm and a pH of 9.

[0062] (3) 0.3 g of natural pyrite (2 g / L Pyrite in the reaction bottle), 0.15 g of natural pyrite + 0.15 g of goethite (1 g / L Pyrite + 1 g / L Goethite in the reaction bottle), 0.3 g of natural pyrite + 0.15 g of goethite (2 g / L Pyrite + 1 g / L Goethite in the reaction bottle), and 0.45 g of natural pyrite + 0.15 g of goethite (3 g / L Pyrite + 1 g / L Goethite in the reaction bottle) were added to each reaction bottle, respectively, and reacted in a shaker at 300 r / min and 25°C for 360 min. After the reaction, the residual metronidazole concentration was determined by high performance liquid chromatography.

[0063] As Figures 1-4The reaction effect is 3g / L Pyrite + 1g / L Goethite > 2g / L Pyrite + 1g / L Goethite > 1g / L Pyrite + 1g / L Goethite > 2g / L Pyrite. Under the conditions of pH 7, 8, 9, 3g / L Pyrite + 1g / L Goethite can degrade 10ppm metronidazole in 60min, and the reaction speed is fast.

[0064] Example 5

[0065] (1) Take natural pyrite, crush and sieve to obtain 100 mesh natural pyrite powder, and then use; take goethite, sieve to obtain 100 mesh goethite, and then use.

[0066] (2) Take 6 250mL reaction bottles, add 150mL rainwater system to each reaction bottle, add 0.01g metronidazole powder, shake well, and adjust the pH of the mixed solution to 7.46 to obtain artificial synthetic metronidazole wastewater with pH 7.46 and concentration of 10ppm.

[0067] (3) Add 0.15g of natural pyrite (containing 1g / L Pyrite in the reaction bottle), 0.15g of goethite (containing 1g / L Goethite in the reaction bottle), 0.15g of natural pyrite + 0.15g of goethite (containing 1g / L Pyrite + 1g / L Goethite in the reaction bottle), 0.3g of natural pyrite + 0.15g of goethite (containing 2g / L Pyrite + 1g / L Goethite in the reaction bottle), 0.45g of natural pyrite + 0.15g of goethite (containing 3g / L Pyrite + 1g / L Goethite in the reaction bottle), and 0.3g of natural pyrite + 0.3g of goethite (containing 2g / L Pyrite + 2g / L Goethite in the reaction bottle) to each reaction bottle respectively, and react in a shaker at a speed of 300r / min and 25℃. After the reaction is completed, the concentration of residual metronidazole is determined by high performance liquid chromatography.

[0068] Figure 5 The curve of Example 5 for removing 10ppm metronidazole in 360min is shown in the figure; Figure 6The graph of removing 10 ppm metronidazole within 10 days for Example 5, wherein Figure a is the graph of removing 10 ppm metronidazole within 10 days for 1 g / L natural pyrite + 1 g / L goethite, 1 g / L natural pyrite, 1 g / L goethite, Figure b is the graph of removing 10 ppm metronidazole within 10 days for 2 g / L natural pyrite + 1 g / L goethite, Figure c is the graph of removing 10 ppm metronidazole within 10 days for 3 g / L natural pyrite + 1 g / L goethite, and Figure d is the graph of removing 10 ppm metronidazole within 10 days for 2 g / L natural pyrite + 2 g / L goethite. Figure 5 and Figure 6 It can be seen that the reaction effect is 3 g / L Pyrite + 1 g / L Goethite > 2 g / L Pyrite + 2 g / L Goethite > 2 g / L Pyrite + 1 g / L Goethite > 1 g / L Pyrite + 1 g / L Goethite > 1 g / L Pyrite > 1 g / L Goethite.

[0069] Example 6

[0070] (1) Take natural pyrite, crush and sieve to obtain 100 mesh natural pyrite powder, and then use; sieve the goethite to obtain 100 mesh goethite, and then use.

[0071] (2) Take 6 250 mL reaction bottles, add 150 mL acetic acid-sodium acetate buffer solution to each reaction bottle, add 0.02 g metronidazole powder, shake well, and adjust the pH of the mixture to 6 to obtain artificial synthetic metronidazole wastewater with a pH of 6 and a concentration of 20 ppm.

[0072] (3) In each reaction bottle, 0.15 g of natural pyrite + 0.15 g of goethite (1 g / L Pyrite + 1 g / L Goethite in the reaction bottle), 0.3 g of natural pyrite + 0.15 g of goethite (2 g / L Pyrite + 1 g / L Goethite in the reaction bottle), 0.45 g of natural pyrite + 0.15 g of goethite (3 g / L Pyrite + 1 g / L Goethite in the reaction bottle), 0.15 g of natural pyrite + 0.3 g of goethite (1 g / L Pyrite + 2 g / L Goethite in the reaction bottle), 0.3 g of natural pyrite + 0.3 g of goethite (2 g / L Pyrite + 2 g / L Goethite in the reaction bottle), 0.15 g of natural pyrite + 0.45 g of goethite (1 g / L Pyrite + 3 g / L Goethite in the reaction bottle) were added, and the reaction was carried out in a shaker at 300 r / min and 25°C for 360 min. After the reaction, the residual metronidazole concentration was determined by high performance liquid chromatography.

[0073] Example 7

[0074] (1) Natural pyrite was taken, crushed and sieved to obtain 100 mesh natural pyrite powder, which was used as received; goethite was sieved to obtain 100 mesh goethite, which was used as received.

[0075] (2) Six 250 mL reaction bottles were taken, 150 mL of MES buffer solution was added to each reaction bottle, 0.02 g of metronidazole powder was added, shaken well, and the pH of the mixture was adjusted to 7 to obtain artificial synthetic metronidazole wastewater with a pH of 7 and a concentration of 20 ppm.

[0076] (3) In each reaction bottle, 0.15 g of natural pyrite + 0.15 g of goethite (1 g / L Pyrite + 1 g / L Goethite in the reaction bottle), 0.3 g of natural pyrite + 0.15 g of goethite (2 g / L Pyrite + 1 g / L Goethite in the reaction bottle), 0.45 g of natural pyrite + 0.15 g of goethite (3 g / L Pyrite + 1 g / L Goethite in the reaction bottle), 0.15 g of natural pyrite + 0.3 g of goethite (1 g / L Pyrite + 2 g / L Goethite in the reaction bottle), 0.3 g of natural pyrite + 0.3 g of goethite (2 g / L Pyrite + 2 g / L Goethite in the reaction bottle), 0.15 g of natural pyrite + 0.45 g of goethite (1 g / L Pyrite + 3 g / L Goethite in the reaction bottle) were added, and the reaction was carried out in a shaker at 300 r / min and 25°C for 360 min. After the reaction, the residual metronidazole concentration was determined by high performance liquid chromatography.

[0077] Example 8

[0078] (1) Natural pyrite was taken, crushed and sieved to obtain 100 mesh natural pyrite powder, which was used as needed; goethite was sieved to obtain 100 mesh goethite, which was used as needed.

[0079] (2) Six 250 mL reaction bottles were taken, 150 mL of Tris-HCl buffer solution was added to each reaction bottle, 0.02 g of metronidazole powder was added, shaken, and the pH of the mixture was adjusted to 8 to obtain artificial synthetic metronidazole wastewater with a pH of 8 and a concentration of 20 ppm.

[0080] (3) 0.15 g of natural pyrite + 0.15 g of goethite (the reaction bottle contains 1 g / L Pyrite + 1 g / L Goethite), 0.3 g of natural pyrite + 0.15 g of goethite (the reaction bottle contains 2 g / L Pyrite + 1 g / L Goethite), 0.45 g of natural pyrite + 0.15 g of goethite (the reaction bottle contains 3 g / L Pyrite + 1 g / L Goethite), 0.15 g of natural pyrite + 0.3 g of goethite (the reaction bottle contains 1 g / L Pyrite + 2 g / L Goethite), 0.3 g of natural pyrite + 0.3 g of goethite (the reaction bottle contains 2 g / L Pyrite + 2 g / L Goethite), 0.15 g of natural pyrite + 0.45 g of goethite (the reaction bottle contains 1 g / L Pyrite + 3g / L Goethite) and reacted in an oscillator at 300 rpm and 25°C for 360 min. After the reaction, the concentration of residual metronidazole was determined by high performance liquid chromatography.

[0081] Example 9

[0082] (1) Take natural pyrite, crush and sieve it to obtain 100-mesh natural pyrite powder for standby use; sieve goethite to obtain goethite with a particle size of 100 mesh for standby use.

[0083] (2) Take 6 250 mL reaction bottles, add 150 mL of Tris-HCl buffer solution to each reaction bottle, add 0.02 g of metronidazole powder, shake well, and adjust the pH of the mixture to 9 to obtain artificially synthesized metronidazole wastewater with a pH of 9 and a concentration of 20 ppm.

[0084] (3) In each reaction bottle, 0.15 g of natural pyrite + 0.15 g of goethite (1 g / L Pyrite + 1 g / L Goethite in the reaction bottle), 0.3 g of natural pyrite + 0.15 g of goethite (2 g / L Pyrite + 1 g / L Goethite in the reaction bottle), 0.45 g of natural pyrite + 0.15 g of goethite (3 g / L Pyrite + 1 g / L Goethite in the reaction bottle), 0.15 g of natural pyrite + 0.3 g of goethite (1 g / L Pyrite + 2 g / L Goethite in the reaction bottle), 0.3 g of natural pyrite + 0.3 g of goethite (2 g / L Pyrite + 2 g / L Goethite in the reaction bottle), 0.15 g of natural pyrite + 0.45 g of goethite (1 g / L Pyrite + 3 g / L Goethite in the reaction bottle) were added, and the reaction was carried out in a shaker at 300 r / min and 25°C for 360 min. After the reaction, the concentration of residual metronidazole was determined by high performance liquid chromatography.

[0085] The removal efficiency values of Examples 6-9 are shown in Table 1. As shown in Table 1, the removal curves of Examples 6-9 within 360 min are shown in Figure 1, and the reaction effect is 2 g / L Pyrite + 2 g / L Goethite > 3 g / L Pyrite + 1 g / L Goethite > 2 g / L Pyrite + 1 g / L Goethite. When the pH is 9, the removal rate of 2 g / L Pyrite + 2 g / L Goethite is the fastest, and 20 ppm of metronidazole can be degraded within 30 min, and the reaction speed is the fastest. Figures 7-10

[0086] Table 1

[0087]

[0088]

[0089] Example 10

[0090] (1) Take natural pyrite, crush and sieve to obtain 100 mesh natural pyrite powder, and then use; sieve the goethite to obtain 100 mesh goethite.

[0091] (2) Take 4 250 mL reaction bottles, add 150 mL of acetic acid-sodium acetate buffer solution to each reaction bottle, add 0.03 g of metronidazole powder, shake well, and adjust the pH of the mixture to 6 to obtain artificial synthetic metronidazole wastewater with a pH of 6 and a concentration of 30 ppm.

[0092] ​(3) 0.3 g of natural pyrite (2 g / L Pyrite in the reaction bottle), 0.15 g of natural pyrite + 0.15 g of goethite (1 g / L Pyrite + 1 g / L Goethite in the reaction bottle), 0.3 g of natural pyrite + 0.15 g of goethite (2 g / L Pyrite + 1 g / L Goethite in the reaction bottle), 0.15 g of natural pyrite + 0.3 g of goethite (1 g / L Pyrite + 2 g / L Goethite in the reaction bottle) were added to each reaction bottle respectively, and reacted in a shaker at 300 r / min and 25°C for 360 min. After the reaction, the residual metronidazole concentration was determined by high performance liquid chromatography.

[0093] Example 11

[0094] (1) Natural pyrite was taken, crushed and sieved to obtain 100 mesh natural pyrite powder, which was used as needed; goethite was sieved to obtain 100 mesh goethite, which was used as needed.

[0095] (2) Four 250 mL reaction bottles were taken, 150 mL of MES buffer solution was added to each reaction bottle, 0.03 g of metronidazole powder was added, shaken well, and the pH of the mixture was adjusted to 7 to obtain artificial synthetic metronidazole wastewater with a pH of 7 and a concentration of 30 ppm.

[0096] (3) 0.3 g of natural pyrite (2 g / L Pyrite in the reaction bottle), 0.15 g of natural pyrite + 0.15 g of goethite (1 g / L Pyrite + 1 g / L Goethite in the reaction bottle), 0.3 g of natural pyrite + 0.15 g of goethite (2 g / L Pyrite + 1 g / L Goethite in the reaction bottle), 0.15 g of natural pyrite + 0.3 g of goethite (1 g / L Pyrite + 2 g / L Goethite in the reaction bottle) were added to each reaction bottle respectively, and reacted in a shaker at 300 r / min and 25°C for 360 min. After the reaction, the residual metronidazole concentration was determined by high performance liquid chromatography.

[0097] Example 12

[0098] (1) Natural pyrite was taken, crushed and sieved to obtain 100 mesh natural pyrite powder, which was used as needed; goethite was sieved to obtain 100 mesh goethite, which was used as needed.

[0099] (2) Take 4 250 mL reaction bottles, add 150 mL Tris-HCl buffer solution to each reaction bottle, add 0.03 g metronidazole powder, shake well, adjust the pH of the mixture to 8, and obtain the pH 8, concentration of 30 ppm of artificial synthetic metronidazole wastewater.

[0100] (3) Add 0.3 g of natural pyrite (reaction bottle contains 2 g / L Pyrite), 0.15 g of natural pyrite + 0.15 g of goethite (reaction bottle contains 1 g / L Pyrite + 1 g / L Goethite), 0.3 g of natural pyrite + 0.15 g of goethite (reaction bottle contains 2 g / L Pyrite + 1 g / L Goethite), 0.15 g of natural pyrite + 0.3 g of goethite (reaction bottle contains 1 g / L Pyrite + 2 g / L Goethite) to each reaction bottle, respectively, and react in a shaker at 300 r / min and 25°C for 360 min. After the reaction is completed, the concentration of residual metronidazole is determined by high performance liquid chromatography.

[0101] Example 13

[0102] (1) Take natural pyrite, crush and sieve to obtain 100 mesh natural pyrite powder, and then use; sieve the goethite to obtain 100 mesh goethite for use.

[0103] (2) Take 4 250 mL reaction bottles, add 150 mL Tris-HCl buffer solution to each reaction bottle, add 0.03 g metronidazole powder, shake well, adjust the pH of the mixture to 9, and obtain the pH 9, concentration of 30 ppm of artificial synthetic metronidazole wastewater.

[0104] (3) Add 0.3 g of natural pyrite (reaction bottle contains 2 g / L Pyrite), 0.15 g of natural pyrite + 0.15 g of goethite (reaction bottle contains 1 g / L Pyrite + 1 g / L Goethite), 0.3 g of natural pyrite + 0.15 g of goethite (reaction bottle contains 2 g / L Pyrite + 1 g / L Goethite), 0.15 g of natural pyrite + 0.3 g of goethite (reaction bottle contains 1 g / L Pyrite + 2 g / L Goethite) to each reaction bottle, respectively, and react in a shaker at 300 r / min and 25°C for 360 min. After the reaction is completed, the concentration of residual metronidazole is determined by high performance liquid chromatography.

[0105] As Figures 11-14The graph shows the removal of an initial concentration of 30 ppm metronidazole by Examples 10-13 over 360 minutes. The synergistic removal of pyrite and goethite is superior to the removal of pyrite alone.

[0106] Example 14

[0107] (1) Take natural pyrite, crush and sieve to obtain 100 mesh natural pyrite powder, and then use; sieve goethite to obtain 100 mesh goethite, and then use.

[0108] (2) Prepare artificial chloramphenicol wastewater with pH of 6, 7, 8, 9, and 10, and concentration of 20 ppm, respectively. The specific preparation method is as follows: take 4 250 mL reaction bottles, add 150 mL acetic acid-sodium acetate buffer solution to each reaction bottle, add 0.02 g chloramphenicol powder, shake well, and adjust the pH of the mixture to 6 to obtain artificial chloramphenicol wastewater with pH of 6 and concentration of 10 ppm; take 4 250 mL reaction bottles, add 150 mL MBS buffer solution to each reaction bottle, add 0.02 g chloramphenicol powder, shake well, and adjust the pH of the mixture to 7 to obtain artificial chloramphenicol wastewater with pH of 7 and concentration of 20 ppm; take 4 250 mL reaction bottles, add 150 mL Tris-HCl buffer solution to each reaction bottle, add 0.02 g chloramphenicol powder, shake well, and adjust the pH of the mixture to 8 to obtain artificial chloramphenicol wastewater with pH of 8 and concentration of 20 ppm; take 4 250 mL reaction bottles, add 150 mL Tris-HCl buffer solution to each reaction bottle, add 0.02 g chloramphenicol powder, shake well, and adjust the pH of the mixture to 9 to obtain artificial chloramphenicol wastewater with pH of 9 and concentration of 20 ppm; take 4 250 mL reaction bottles, add 150 mL glycine buffer solution to each reaction bottle, add 0.02 g chloramphenicol powder, shake well, and adjust the pH of the mixture to 10 to obtain artificial chloramphenicol wastewater with pH of 10 and concentration of 20 ppm.

[0109] (3) 0.45 g of natural pyrite (containing 3 g / L Pyrite in the reaction flask), 0.45 g of natural pyrite + 0.15 g of goethite (containing 3 g / L Pyrite + 1 g / L Goethite in the reaction flask), 0.3 g of natural pyrite + 0.3 g of goethite (containing 2 g / L Pyrite + 2 g / L Goethite in the reaction flask), and 0.15 g of natural pyrite + 0.45 g of goethite (containing 1 g / L Pyrite + 3 g / L Goethite in the reaction flask) were added to the reaction flasks under different pH conditions, and the mixture was reacted in an oscillator at a speed of 300 r / min and 25°C for 360 min. After the reaction, the concentration of residual chloramphenicol was determined by high performance liquid chromatography.

[0110] like Figure 15 Shown is a graph showing the removal of 20 ppm of chloramphenicol within 360 min at pH 6 in Example 14, wherein Figure a is a graph showing the removal of 20 ppm of chloramphenicol by 3 g / L natural pyrite and 3 g / L natural pyrite + 1 g / L goethite within 360 min of the reaction, Figure b is a graph showing the removal of 20 ppm of chloramphenicol by 2 g / L natural pyrite + 2 g / L goethite within 360 min of the reaction, and Figure c is a graph showing the removal of 20 ppm of chloramphenicol by 1 g / L natural pyrite + 3 g / L goethite within 360 min of the reaction; Figure 16 This is a graph showing the removal of 20 ppm of chloramphenicol within 360 min at pH 7 in Example 14; Figure 17 This is a curve chart of Example 14 for removing 20 ppm of chloramphenicol within 360 min at a pH of 8;

[0111] Figure 18 The graph of Example 14 at pH 9, 20 ppm of chloramphenicol is removed within 360 min, wherein Figure a is a graph showing that 1 g / L natural pyrite + 3 g / L goethite removes 20 ppm of chloramphenicol within 360 min of the reaction, Figure b is a graph showing that 3 g / L natural pyrite removes 20 ppm of chloramphenicol within 360 min of the reaction, Figure c is a graph showing that 3 g / L natural pyrite + 1 g / L goethite removes 20 ppm of chloramphenicol within 360 min of the reaction, and Figure d is a graph showing that 2 g / L natural pyrite + 2 g / L goethite removes 20 ppm of chloramphenicol within 360 min of the reaction; Figure 19Figure 1 shows the curves of Example 14 for removing 20 ppm chloramphenicol at pH 10 within 360 min, wherein Figure a is a curve of 1 g / L natural pyrite + 3 g / L goethite for removing 20 ppm chloramphenicol within 360 min of reaction, Figure b is a curve of 3 g / L natural pyrite for removing 20 ppm chloramphenicol within 360 min of reaction, Figure c is a curve of 3 g / L natural pyrite + 1 g / L goethite for removing 20 ppm chloramphenicol within 360 min of reaction, and Figure d is a curve of 2 g / L natural pyrite + 2 g / L goethite for removing 20 ppm chloramphenicol within 360 min of reaction.

[0112] When the pH is 10, the removal efficiency of chloramphenicol by pyrite alone and pyrite and goethite in combination reaches 99% within 10 min of reaction. The removal effect is best at pH 10, followed by pH 9, 8, 7, and worst at pH 6.

[0113] As shown in Figure 2, the SEM image of the minerals after removal of chloramphenicol by 0.45 g of natural pyrite + 0.15 g of goethite at pH 9 shows that a large amount of green rust is generated on the surface of the minerals, and it is just due to the generation of this active substance that substances such as metronidazole and chloramphenicol in the system can be removed. Figure 20

[0114] At pH 6 and 7, pyrite can activate Fe(III) in goethite to be reduced to Fe(II) (equation (1)), and the dissolution amount of Fe(II) in the system increases, thereby reducing substances with oxidizing properties such as metronidazole and chloramphenicol in the system.

[0115] α-FeOOH + e - + 3H + → Fe 2+ + 2H2O (1)

[0116] At pH 8 and 9, pyrite and goethite react with sulfate in alkaline conditions to generate sulfate-type green rust (Fe(II)4Fe(III)2(OH) 12 SO4) (equation (2)), thereby reducing substances with oxidizing properties such as metronidazole and chloramphenicol in the system. In addition, the reaction is a process of consuming OH - , and the pH in the system will decrease, affecting the removal efficiency. The present application sets a buffer system to ensure that pyrite and goethite are not affected by the pH in the process of removing metronidazole, and maintain a relatively high removal efficiency.

[0117] 2Fe(III)OOH + 4Fe(II) + 6OH - + 2H2O + SO4 2- ​→ Fe(II)4Fe(III)2(OH) 12 SO4 (2)

[0118] Pyrite and goethite react with sulfate in alkaline condition to form magnetite (Fe(II)Fe(III)2O4) (equation (3)) which can oxidize substances with oxidizability in magnetite reduction system such as metronidazole, chloramphenicol and the like. In addition, the reaction is a process of consuming OH - , and the pH in the system will be reduced, affecting the removal efficiency. The present application sets a buffer system to ensure that pyrite and goethite are not affected by pH during the removal of metronidazole, and maintain relatively efficient removal.

[0119] 2Fe(III)OOH + Fe(II) + 2OH - → Fe(II)Fe(III)2O4 + 2H2O (3)

[0120] Comparative Example 1

[0121] (1) Take natural pyrite, crush and sieve to obtain 100 mesh natural pyrite powder, and then use;

[0122] (2) Prepare artificial synthetic metronidazole wastewater with pH of 6, 7, 8 and 9 and concentration of 20 ppm respectively. The specific preparation method is as follows: take 250 mL reaction bottles, add 150 mL acetic acid-sodium acetate buffer solution in each reaction bottle, add 0.02 g metronidazole powder, shake well, and adjust the pH of the mixture to 6 to obtain artificial synthetic metronidazole wastewater with pH of 6 and concentration of 20 ppm; take 250 mL reaction bottles, add 150 mL MBS buffer solution in each reaction bottle, add 0.02 g metronidazole powder, shake well, and adjust the pH of the mixture to 7 to obtain artificial synthetic metronidazole wastewater with pH of 7 and concentration of 20 ppm; take 250 mL reaction bottles, add 150 mL Tris-HCl buffer solution in each reaction bottle, add 0.02 g metronidazole powder, shake well, and adjust the pH of the mixture to 8 to obtain artificial synthetic metronidazole wastewater with pH of 8 and concentration of 20 ppm; take 250 mL reaction bottles, add 150 mL Tris-HCl buffer solution in each reaction bottle, add 0.02 g metronidazole powder, shake well, and adjust the pH of the mixture to 9 to obtain artificial synthetic metronidazole wastewater with pH of 9 and concentration of 20 ppm.

[0123] (3) Add 0.3 g of natural pyrite (containing 2 g / L pyrite in the reaction bottle) to each reaction bottle, and react in a shaker at a speed of 300 r / min and a temperature of 25℃ for 360 min. After the reaction is completed, the concentration of residual metronidazole is determined by high performance liquid chromatography.

[0124] Table 2

[0125]

[0126] The removal efficiency values of pyrite alone at pH 6-9 are shown in Table 2. The experimental results show that the removal of metronidazole by pyrite alone is worse than that by the combination of pyrite and goethite.

[0127] Comparative Example 2

[0128] (1) After sieving, goethite powder having a particle size of 100 mesh was obtained and used as is;

[0129] (2) Artificially synthesized metronidazole wastewater having a concentration of 10 ppm at pH 6, 7, 8, and 9 was prepared, respectively. The specific preparation method is as follows: 150 mL of acetic acid-sodium acetate buffer solution was added to a 250 mL reaction bottle, 0.01 g of metronidazole powder was added, and the mixture was shaken until uniform. The pH of the mixture was adjusted to 6 to obtain artificially synthesized metronidazole wastewater having a concentration of 10 ppm at pH 6. 150 mL of MES buffer solution was added to a 250 mL reaction bottle, 0.01 g of metronidazole powder was added, and the mixture was shaken until uniform. The pH of the mixture was adjusted to 7 to obtain artificially synthesized metronidazole wastewater having a concentration of 10 ppm at pH 7. 150 mL of Tris-HCl buffer solution was added to a 250 mL reaction bottle, 0.01 g of metronidazole powder was added, and the mixture was shaken until uniform. The pH of the mixture was adjusted to 8 to obtain artificially synthesized metronidazole wastewater having a concentration of 10 ppm at pH 8. 150 mL of Tris-HCl buffer solution was added to a 250 mL reaction bottle, 0.01 g of metronidazole powder was added, and the mixture was shaken until uniform. The pH of the mixture was adjusted to 9 to obtain artificially synthesized metronidazole wastewater having a concentration of 10 ppm at pH 9. 150 mL of glycine buffer solution was added to a 250 mL reaction bottle, 0.01 g of metronidazole powder was added, and the mixture was shaken until uniform. The pH of the mixture was adjusted to 10 to obtain artificially synthesized metronidazole wastewater having a concentration of 10 ppm at pH 10.

[0130] (3) 0.3 g of goethite (2 g / L of goethite was contained in the reaction bottle) was added to each reaction bottle, and the reaction was carried out in a shaker at a rotation speed of 300 r / min and 25°C for 360 min. After the reaction was completed, the concentration of residual metronidazole was measured by high performance liquid chromatography.

[0131] After the reaction was completed at pH 6-10, a large amount of metronidazole remained in the system, which was similar to the initial concentration. The removal rate of goethite was 0-2%, and thus, goethite alone had no removal effect on metronidazole.

[0132] Comparative Example 3

[0133] (1) Take the synthetic pyrite (FeS2, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.), after crushing and sieving, get 100 mesh synthetic pyrite powder, then use; after sieving, get 100 mesh goethite for use.

[0134] (2) Prepare 20 ppm of synthetic metronidazole wastewater with pH of 6, 7, 8 and 9 respectively. The specific preparation method is as follows: take 7 250 mL reaction bottles, add 150 mL of acetic acid-sodium acetate buffer solution to each reaction bottle, add 0.02 g of metronidazole powder, shake well, adjust the pH of the mixture to 6, get 10 ppm of synthetic metronidazole wastewater with pH of 6; take 7 250 mL reaction bottles, add 150 mL of MES buffer solution to each reaction bottle, add 0.02 g of metronidazole powder, shake well, adjust the pH of the mixture to 7, get 20 ppm of synthetic metronidazole wastewater with pH of 7; take 7 250 mL reaction bottles, add 150 mL of Tris-HCl buffer solution to each reaction bottle, add 0.02 g of metronidazole powder, shake well, adjust the pH of the mixture to 8, get 20 ppm of synthetic metronidazole wastewater with pH of 8; take 7 250 mL reaction bottles, add 150 mL of Tris-HCl buffer solution to each reaction bottle, add 0.02 g of metronidazole powder, shake well, adjust the pH of the mixture to 9, get 20 ppm of synthetic metronidazole wastewater with pH of 9.

[0135] (3) 0.45 g of artificial pyrite (3 g / L Pyrite in the reaction bottle), 0.15 g of artificial pyrite + 0.15 g of goethite (1 g / L Pyrite + 1 g / L Goethite in the reaction bottle), 0.3 g of artificial pyrite + 0.15 g of goethite (2 g / L Pyrite + 1 g / L Goethite in the reaction bottle), 0.45 g of artificial pyrite + 0.15 g of goethite (3 g / L Pyrite + 1 g / L Goethite in the reaction bottle), 0.15 g of artificial pyrite + 0.3 g of goethite (1 g / L Pyrite + 2 g / L Goethite in the reaction bottle), 0.3 g of artificial pyrite + 0.3 g of goethite (2 g / L Pyrite + 2 g / L Goethite in the reaction bottle), 0.15 g of artificial pyrite + 0.45 g of goethite (1 g / L Pyrite + 3 g / L Goethite in the reaction bottle) were added in the reaction bottles under different pH conditions, respectively, and reacted in a shaker at a rotation speed of 300 r / min and 25°C for 360 min. After the reaction, the concentration of residual metronidazole was determined by high performance liquid chromatography.

[0136] As shown in Figures 21-24 is a removal curve of Comparative Example 3, Figure 21 is a curve of Comparative Example 3 for removing 20 ppm of metronidazole within 360 min at pH 6, wherein Fig. a is a curve of 1 g / L artificial pyrite + 3 g / L goethite for removing 20 ppm of metronidazole within 360 min, Fig. b is a curve of 3 g / L artificial pyrite for removing 20 ppm of metronidazole within 360 min, Fig. c is a curve of 1 g / L artificial pyrite + 1 g / L goethite for removing 20 ppm of metronidazole within 360 min, Fig. d is a curve of 2 g / L artificial pyrite + 1 g / L goethite for removing 20 ppm of metronidazole within 360 min, Fig. e is a curve of 1 g / L artificial pyrite + 2 g / L goethite for removing 20 ppm of metronidazole within 360 min, Fig. f is a curve of 3 g / L artificial pyrite + 1 g / L goethite for removing 20 ppm of metronidazole within 360 min, and Fig. g is a curve of 2 g / L artificial pyrite + 2 g / L goethite for removing 20 ppm of metronidazole within 360 min; Figure 22 is a curve of Comparative Example 3 for removing 20 ppm of metronidazole within 360 min at pH 7; Figure 23 is a curve of Comparative Example 3 for removing 20 ppm of metronidazole within 360 min at pH 8; Figure 24The figure of removing 20 ppm metronidazole by the comparative example 3 within 360 min at pH 9, wherein, figure a is the figure of removing 20 ppm metronidazole by 3 g / L synthetic pyrite, 2 g / L synthetic pyrite + 1 g / L goethite, 3 g / L synthetic pyrite + 1 g / L goethite, 2 g / L synthetic pyrite + 2 g / L goethite within 360 min of reaction, figure b is the figure of removing 20 ppm metronidazole by 1 g / L synthetic pyrite + 3 g / L goethite within 360 min of reaction, figure c is the figure of removing 20 ppm metronidazole by 1 g / L synthetic pyrite + 2 g / L goethite within 360 min of reaction, figure d is the figure of removing 20 ppm metronidazole by 1 g / L synthetic pyrite + 1 g / L goethite within 360 min of reaction.

[0137] The efficiency of removing metronidazole by the synthetic pyrite of the comparative example 3 is lower than that of the natural pyrite.

[0138] Comparative example 4

[0139] (1) The natural pyrite was crushed and sieved to obtain 100 mesh natural pyrite powder, which was used later; the goethite was sieved to obtain 100 mesh goethite, which was used later.

[0140] (2) Two 250 mL reaction bottles were taken, 0.01 g of metronidazole powder was added to each reaction bottle and shaken, the pH of the metronidazole solution was adjusted to 9 with 0.1 M NaOH to obtain metronidazole wastewater with an initial pH of 9 and a concentration of 10 ppm; two 250 mL reaction bottles were taken, 0.01 g of metronidazole powder was added to each reaction bottle and shaken, the pH of the metronidazole solution was adjusted to 7 with 0.1 M NaOH to obtain metronidazole wastewater with an initial pH of 7 and a concentration of 10 ppm.

[0141] (3) 0.3 g of natural pyrite (containing 2 g / L Pyrite in the reaction bottle) and 0.3 g of natural pyrite + 0.15 g of goethite (containing 2 g / L Pyrite + 1 g / L Goethite in the reaction bottle) were added to each reaction bottle respectively, and reacted in a 25℃ shaker for 360 min. After the reaction, the concentration of residual metronidazole was determined by high performance liquid chromatography.

[0142] After the reaction, the removal efficiency of 0.3 g of natural pyrite is 3.1% under the condition that the initial pH is 7, and the pH value of the solution after the reaction is 3.51; the removal efficiency of 0.3 g of natural pyrite + 0.15 g of goethite is 5.4%, and the pH value of the solution after the reaction is 3.57; the removal efficiency of 0.3 g of natural pyrite is 7.1% under the condition that the initial pH is 9, and the pH value of the solution after the reaction is 5.45; the removal efficiency of 0.3 g of natural pyrite + 0.15 g of goethite is 24.5%, and the pH value of the solution after the reaction is 5.70.

[0143] Example 15

[0144] (1) Take natural pyrite, crush and sieve to obtain 100-mesh natural pyrite powder, and then use; sieve the goethite to obtain 100-mesh goethite, and then use.

[0145] (2) Take 3 250-mL reaction bottles, and add 150 mL of rainwater (a collection tank is arranged on the ground, and rainwater flows through the ground and is collected in the collection tank after rain, and the water in the collection tank is used as the rainwater in the experiment) to each reaction bottle.

[0146] (3) Add 0.45 g of natural pyrite + 0.15 g of goethite (containing 3 g / L of pyrite + 1 g / L of goethite) to the reaction bottle, 0.3 g of natural pyrite + 0.3 g of goethite (containing 2 g / L of pyrite + 2 g / L of goethite), and 0.15 g of natural pyrite + 0.45 g of goethite (containing 2 g / L of pyrite + 2 g / L of goethite) to the reaction bottle, respectively, and react in a shaker at a rotation speed of 200 r / min and 25°C for 360 min. After the reaction, the concentrations of residual metronidazole and chloramphenicol are determined by high performance liquid chromatography.

[0147] Before the reaction, the concentration of metronidazole in the rainwater is 10 ppm, and the concentration of chloramphenicol is 5 ppm; after the reaction for 360 min, there is no residual metronidazole and chloramphenicol in the reaction systems of 3 g / L of pyrite + 1 g / L of goethite, 2 g / L of pyrite + 2 g / L of goethite, and 2 g / L of pyrite + 2 g / L of goethite.

[0148] The above only describes the preferred embodiments of the present application, and is not used to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for removing antibiotics by mixing goethite and pyrite, characterized in that: The steps include: (1) Crushing pyrite and goethite; (2) Preparation of antibiotic wastewater; (3) Mixing pyrite and goethite with antibiotic wastewater in different proportions for reaction; In step (2), the antibiotic wastewater contains metronidazole or chloramphenicol, the pH value of the antibiotic wastewater is 6-10, and the concentration of the metronidazole or chloramphenicol is 5-30 ppm; In the step (2), the antibiotic wastewater is a mixture of buffer solutions of different pH values ​​and metronidazole or chloramphenicol. The antibiotic wastewater with a pH value of 6 is a mixture of acetic acid-sodium acetate buffer and metronidazole or chloramphenicol. The antibiotic wastewater with a pH value of 7 is a mixture of MES buffer and metronidazole or chloramphenicol. The antibiotic wastewater with a pH value of 8 or 9 is a mixture of Tris-HCl buffer and metronidazole or chloramphenicol. The antibiotic wastewater with a pH value of 10 is a mixture of glycine buffer and metronidazole or chloramphenicol.

2. A method for removing antibiotics by mixing goethite and pyrite as claimed in claim 1, characterized in that: In the step (1), the particle size of pyrite is 100-400 mesh, and the particle size of goethite is 100-400 mesh.

3. A method for removing antibiotics by mixing goethite and pyrite as claimed in claim 1, characterized in that: In the step (3), the mass ratio of pyrite to goethite is (1 / 3~3):

1.

4. Use of the method for removing antibiotics by mixing goethite and pyrite as claimed in any one of claims 1 to 3 in treating rainwater contaminated by antibiotics.

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