Method for promoting as oxidation by antibiotic drug molecules activated goethite

Abstract

The application discloses a method for promoting As oxidation by activating goethite with antibiotic molecules, and comprises the following steps: S1, goethite preparation; S2, adjusting the pH of a solution containing antibiotic molecules and trivalent arsenic to 5.5-6.5, adding goethite, and carrying out reaction in dark at 23-27 DEG C and 150-190 rpm for 2-72 h to realize the activation of goethite by antibiotic molecules and further complete As oxidation; wherein the concentration of antibiotic molecules in the solution is 45-55 mu M, the concentration of trivalent arsenic is 2.67 mu M, and the adding ratio of goethite to the solution to be treated is 30-50 mg:20 ml; the application firstly proposes that antibiotic molecules can complex and reduce the surface Fe(III) of goethite to generate Fe(II), further promotes the oxidation of As(III), and provides a brand-new treatment mode for the pollution conversion of composite pollutants.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of goethite treatment, in particular to a method for promoting As oxidation by activating goethite with antibiotic drug molecules. BACKGROUND

[0002] Goethite is widely present in soil and sediments, and is one of the most thermodynamically stable iron oxides. The formation of goethite in soil mainly has the following two ways: 1) re-oxidation of Fe(II)-containing minerals, in which the source of Fe(II) is the weathering of ferrous carbonate and ferrous sulfide or the microbial reduction of iron minerals; 2) transformation of ferrihydrite and lepidocrocite under certain conditions (Zhu Yanping, 2019). Goethite is yellow-brown to red in color, and the crystal is mostly needle-shaped, with a small amount of flaky or columnar (Yang Min, 2021). There are three different types of hydroxyl groups on the surface of goethite, which are divided into single coordination hydroxyl (≡FeOH, type A), double coordination hydroxyl (≡Fe2OH, type C) and triple coordination hydroxyl (≡Fe3OH, type B) according to the coordination number with terminal Fe. Among them, the A-type hydroxyl group is the most active and can complex with ions in the solution through protonation-deprotonation, the B-type hydroxyl group is generally inert and does not participate in the reaction, and the C-type hydroxyl group is an anion hydrogen bonding site (Randall et al., 1999). The chemical formula of goethite is α-FeOOH, which belongs to the orthorhombic system, and the cell parameters are: a = 0.9956 nm, b = 0.3021 nm, c = 0.4608 nm. Under natural conditions, due to changes in ore-forming conditions or the introduction of impurities, absolutely perfect goethite crystals almost do not exist (Schwertmann et al., 1985; Liu et al., 2018). In addition, most of the laboratory synthesized goethite is synthesized through a low-temperature hydrolysis process, and also contains different amounts of defects (Schwertmann et al., 1985; Barrero et al., 2006). The surface defects of goethite are usually in the form of iron vacancies (FeVs) or oxygen vacancies (OVs). The presence of defects has a great influence on the physicochemical properties of goethite (Notini et al., 2018, 2019). For example, Hou et al. found that the surface defects of goethite can promote its adsorption and fixation of arsenic (Hou et al., 2022), and Notini et al. showed that the rich surface defects of goethite increased the rate of microbial reduction by two times (Notini et al., 2019).

[0003] Goethite is the most widespread and stable iron oxide in the environment, and has an important influence on the migration and transformation of pollutants. Studying the transformation process and mechanism of goethite on the composite pollutants of antibiotics and As(III) is of great significance for the transformation and ecological risk prediction of the two pollutants in the environment. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for activating antibiotic drug molecules to promote the oxidation of As in goethite.

[0005] The technical solution of this invention is: a method for activating goethite with antibiotic drug molecules to promote As oxidation, comprising the following steps:

[0006] S1. Preparation of goethite

[0007] Take 80-100 mL of 5 mol / L KOH solution and add it to 180-200 mL of 1 mol / L Fe(NO3)3 solution. Then dilute the mixed solution to 2 L with ultrapure water and seal it. Aging at 65-75℃ for 55-65 h, the precipitate turns yellowish-brown to obtain the synthetic mineral. Then centrifuge the synthetic mineral at 7500-8500 rpm, separate the solid and wash it with ultrapure water 5-8 times. After freeze drying and grinding, store it at 3-5℃ to obtain goethite.

[0008] S2, antibiotic-activated goethite and As oxidation

[0009] The pH of a solution containing antibiotic molecules and trivalent arsenic is adjusted to 5.5-6.5, goethite is added, and the reaction is carried out in the dark at 23-27℃ and 150-190 rpm for 2-72 hours to activate the goethite by the antibiotic molecules and further complete the oxidation of As. The concentration of the antibiotic molecules in the solution is 45-55 μM, the concentration of trivalent arsenic is 2.67 μM, and the ratio of goethite to the solution to be treated is 30-50 mg: 20 ml.

[0010] Explanation: This invention discovers that antibiotic drug molecules can complex and reduce Fe(III) on the surface of goethite to generate Fe(II), while simultaneously undergoing their own transformation. Reduced Fe(II), under the influence of oxygen vacancies on the goethite surface, rapidly undergoes electron transfer with structural Fe(III) to generate highly reactive Fe(III), which directly oxidizes As(III). This process can occur under both anaerobic and aerobic conditions. Furthermore, under aerobic conditions, oxygen vacancies on the goethite surface can accelerate electron transfer between adsorbed O2 and As(III), promoting the direct oxidation of As(III) by O2. After As(III) is oxidized to As(V), it is adsorbed on the goethite surface, reducing its toxicity and bioavailability.

[0011] Furthermore, in S2, the antibiotic drug molecule is any one of gentamicin, oxytetracycline, tetracycline, chlortetracycline, sulfonamide, or sulfamethoxazole.

[0012] Note: The above-mentioned antibiotic molecules have a significant promoting effect on As(III) oxidation and have a good effect.

[0013] Furthermore, it also includes: modifying the goethite prepared by S1;

[0014] The modification process is as follows: goethite is ball-milled at a rate of 350-450 r / min for 5.5-6.5 h, then mixed with 3-5 wt% AlCl3 solution, followed by hydrothermal treatment in water at 180-220℃ for 22-26 h until the surface pore size is 2-5 mm. Visible light treatment is applied simultaneously during the hydrothermal treatment stage. Then, it is calcined at 280-320℃ in an 8-10% H2 atmosphere for 45-75 min. Finally, a carbon layer of 1.5-2.5 nm is coated on the surface of the goethite.

[0015] Note: Grinding needle iron ore can increase the oxygen vacancy density on its surface, thereby increasing the Fe content. 2+ / Fe 3+ The circulation rate is significantly accelerated; pre-doping with Al followed by hydrothermal treatment promotes the exposure of the (110) crystal face of goethite and enhances Fe content. 2+ Anchor point density, making Al 3+ Participating in crystal growth to form a uniform Al-O-Fe structure, in which Al 3+ The stable existence of Fe can promote the neighboring Fe through lattice strain effects. 3+ The reduction (such as by antibiotic drug molecules adsorbed on the surface or coexisting reducing agents) generates more Fe. 2+ Fe 2+ It can activate H2O2 or O2 to produce reactive oxygen species (·OH, ·O2). - (etc.), thereby degrading antibiotic drug molecules; Al-O-Fe and Fe-O-Fe regions can form microscopic heterojunctions, which can promote the separation of photogenerated electrons and holes under visible light, and the hydrothermal generation aperture is conducive to light scattering and multiple reflections, enhancing light absorption efficiency; carbon coating can protect the oxygen vacancy structure.

[0016] Furthermore, the visible light processing method is as follows: at a wavelength of 420-800 nm and an intensity of 50-100 mW / cm². 2 Irradiation under a short-arc xenon lamp with a power of 300-500W;

[0017] Note: The above-mentioned intensity balances catalytic efficiency and energy consumption. Too low an intensity will result in insufficient electron excitation, while too high an intensity may trigger side reactions (such as Al). 3+ Photoreduction). Wavelength confinement matching of the visible light absorption band of goethite / Al-O-Fe, and a hydrothermal temperature ≥180℃ help maintain Fe. 2+Stability, while light further promotes the separation of interfacial charges (it is necessary to avoid exceeding 220°C, which would cause goethite to transform into hematite).

[0018] Furthermore, the carbon layer comprises, from the inside out, a substrate layer, an intermediate transition layer, and a functional layer;

[0019] The carbon layer is prepared by immersing calcined goethite in a citric acid buffer solution with pH=4 at a solid-liquid ratio of 1g:5-7mL to obtain an iron-rich oxide layer. Then, it is immersed in a glucose solution with a concentration of 10-12wt.% at a temperature of 170-180℃ until a base layer with a thickness of 1.5-2nm is formed on the surface, which is referred to as the carbon substrate layer.

[0020] Nitrogen-doped graphene with an N:C mass ratio of 5-8:100 is deposited on the surface of the substrate layer by CVD, with a deposition thickness of 0.3-0.5 nm. Then, a protective atmosphere of 4-5% is introduced, and the temperature is raised to 280-320°C at a heating rate of 5-10°C / min and held for 20-30 min to obtain an intermediate transition layer.

[0021] Then, the surface of the intermediate transition layer is subjected to argon plasma bombardment treatment at a substrate temperature of 145-155℃, a power of 140-150W, and a working pressure of 0.45-0.55Pa for 8-10 minutes. Then, Fe and carbon targets are co-deposited by magnetron sputtering. Finally, the magnetron sputtered material is immersed in an ethylene glycol solution containing FeSO4, ultrasonically treated, and dried under nitrogen protection to obtain a functional layer with a thickness of 0.8-1nm; the molar concentration of FeSO4 is 0.1-0.15mol / L.

[0022] Explanation: High-temperature maintenance after CVD deposition ensures stable bonding of nitrogen-doped graphene. Argon plasma bombardment between the intermediate transition layer and the functional layer forms Fe-NC interface bonds. The gradient carbon layer design utilizes the amorphous carbon in the substrate layer to adsorb tetracycline, while the N-graphene in the intermediate layer conducts electrons, and the Fe in the functional layer... 2+ Clusters enhance the processing effect of antibiotic drug molecules on goethite, forming a synergistic activation chain.

[0023] Furthermore, the protective atmosphere is obtained by mixing H2 and Ar in equal volume ratio;

[0024] Note: Introducing the H2 / Ar mixture protects the Fe generated during calcination. 2+ It is not oxidized and is anchored to Fe through nitrogen defects. 2+ .

[0025] Furthermore, during the magnetron sputtering process, the power ratio of the Fe target to the carbon target is 1:3-5, the vacuum degree is ≤5×10-3Pa, the sputtering pressure is 0.8-1.0Pa, the substrate-target distance is 80-100mm, and the sputtering time is 30-40min;

[0026] Note: Lower Fe target power avoids excessively high sputtering rates, preventing excessive aggregation of Fe atoms in the carbon matrix to form large particles, and ensuring Fe... 2+ Uniform dispersion in 2-3 nm nanoclusters, high carbon target power ensures continuous deposition of carbon matrix, keeps Fe:C atomic ratio stable in the range of 1:4-1:6, and avoids the formation of inactive iron carbide phase (such as Fe3C); vacuum setting can reduce impurity contamination, sputtering gas pressure can control the density of film layer within the above parameters, substrate-target distance can adjust deposition uniformity and optimize deposition effect.

[0027] Furthermore, the ultrasonic treatment is performed for 25-30 minutes at an ultrasonic frequency of 35-45kHz, an ultrasonic power of 200-250W, and a temperature of 25-30℃.

[0028] Note: The above parameters can achieve nano-Fe 2+ The uniform dispersion and anchoring of clusters in ethanol solution enhance the promoting effect of antibiotic drug molecules on goethite.

[0029] Furthermore, after nitrogen-protected drying, a 0.5-0.7 wt% KH2PO4 solution is sprayed onto the surface;

[0030] Note: The increase in surface phosphate groups can effectively enhance the adsorption capacity of As.

[0031] The beneficial effects of this invention are:

[0032] (1) This invention proposes a pollution treatment method in which antibiotic drug molecules can complex and reduce Fe(III) on the surface of goethite to generate Fe(II), while simultaneously undergoing their own transformation. The antibiotic drug molecules activate goethite to produce reduced Fe(II). Under the influence of oxygen vacancies on the goethite surface, the reduced Fe(II) rapidly undergoes electron transfer with the structural Fe(III) of the goethite, generating highly reactive Fe(III), which directly oxidizes As(III). This process can occur under both anaerobic and aerobic conditions. Furthermore, under aerobic conditions, oxygen vacancies on the goethite surface can accelerate electron transfer between adsorbed O2 and As(III), promoting the direct oxidation of As(III) by O2. After As(III) is oxidized to As(V), it is adsorbed on the goethite surface, significantly reducing its toxicity and bioavailability.

[0033] (2) This invention achieves the design of a gradient carbon layer by preparing a carbon layer comprising, from the inside out: a substrate layer, an intermediate transition layer, and a functional layer. The amorphous carbon in the substrate layer adsorbs tetracycline, the N-graphene in the intermediate layer conducts electrons, and the Fe in the functional layer... 2+ Clusters enhance the treatment effect of antibiotic drug molecules on goethite, forming a synergistic activation chain; additionally, argon plasma bombardment between the intermediate transition layer and the functional layer can form Fe-NC interface bonds, thereby inhibiting Fe 2+ The loss of N-doped carbon layers extends the catalytic cycle life, while the N-doped carbon layer acts as an electron bridge, accelerating the oxidation kinetics of As(III). Attached Figure Description

[0034] Figure 1 This is the result of EPR spectrum determination of solid goethite synthesized in Example 1 of this experiment;

[0035] Figure 2 This is a comparison chart of the As(III) oxidation effect in Example 1, Examples 8-13 and Control Group 1-Control Group 2. Detailed Implementation

[0036] The present invention will now be described in more detail with reference to specific embodiments, so as to better demonstrate the advantages of the present invention.

[0037] Example 1: A method for activating goethite-promoting As oxidation using antibiotic drug molecules, comprising the following steps:

[0038] S1. Preparation of goethite

[0039] Take 90 mL of 5 mol / L KOH solution and add it to 190 mL of 1 mol / L Fe(NO3)3 solution. Then dilute the mixed solution to 2 L with ultrapure water and seal it. Aging at 70℃ for 60 h, the precipitate turns yellowish-brown to obtain the synthetic mineral. Then centrifuge the synthetic mineral at 8000 rpm, separate the solid and wash it 7 times with ultrapure water. After freeze drying and grinding, store it at 4℃ to obtain goethite.

[0040] S2, antibiotic-activated goethite and As oxidation

[0041] The pH of a solution containing antibiotic molecules and trivalent arsenic was adjusted to 6.0, goethite was added, and the reaction was carried out at 25°C and 170 rpm in the dark for 36 hours to activate the goethite with antibiotic molecules and further complete the oxidation of As. The concentration of antibiotic molecules in the solution was 50 μM, the concentration of trivalent arsenic was 2.67 μM, and the ratio of goethite to the solution was 40 mg: 20 ml. In S2, the antibiotic molecule was gentamicin.

[0042] Example 2: Unlike Example 1, 80 mL of 5 mol / L KOH solution was added to 180 mL of 1 mol / L Fe(NO3)3 solution. The mixture was then diluted to 2 L with ultrapure water and sealed. It was aged at 65°C for 55 h.

[0043] Example 3: Unlike Example 1, 100 mL of 5 mol / L KOH solution was added to 200 mL of 1 mol / L Fe(NO3)3 solution. The mixture was then diluted to 2 L with ultrapure water and sealed. It was aged at 75°C for 65 h.

[0044] Example 4: Unlike Example 1, the synthesized mineral was then centrifuged at 7500 rpm to separate the solid, washed five times with ultrapure water, freeze-dried, ground, and stored at 3°C ​​to obtain goethite.

[0045] Example 5: Unlike Example 1, the synthesized mineral was then centrifuged at 8500 rpm to separate the solid, washed 8 times with ultrapure water, freeze-dried, ground, and stored at 5°C to obtain goethite.

[0046] Example 6: Unlike Example 1, the pH of the solution containing antibiotic molecules and trivalent arsenic was adjusted to 5.5, goethite was added, and the reaction was carried out at 23°C and 150 rpm in the dark for 2 hours to activate the goethite by the antibiotic molecules and further complete the oxidation of As. The concentration of the antibiotic molecules in the solution was 45 μM, the concentration of trivalent arsenic was 2.67 μM, and the ratio of goethite to the solution to be treated was 30 mg: 20 ml.

[0047] Example 7: Unlike Example 1, the pH of the solution containing antibiotic molecules and trivalent arsenic was adjusted to 6.5, goethite was added, and the reaction was carried out at 27°C and 190 rpm in the dark for 72 hours to activate the goethite by the antibiotic molecules and further complete the oxidation of As. The concentration of the antibiotic molecules in the solution was 55 μM, the concentration of trivalent arsenic was 2.67 μM, and the ratio of goethite to the solution to be treated was 50 mg: 20 ml.

[0048] Example 8: Unlike Example 1, in S2, the tetracycline antibiotic is oxytetracycline.

[0049] Example 9: Unlike Example 1, in S2, the tetracycline antibiotic is tetracycline.

[0050] Example 10: Unlike Example 1, in S2, the tetracycline antibiotic is chlorotetracycline.

[0051] Example 12: Unlike Example 1, in S2, the tetracycline antibiotic is sulfonamide.

[0052] Example 13: Unlike Example 1, in S2, the tetracycline antibiotic is sulfamethoxazole.

[0053] Example 14: Unlike Example 1, it also includes: modifying the goethite prepared in S1;

[0054] The modification process involved ball milling goethite at 400 r / min for 6 h, then incorporating a 4 wt% AlCl3 solution, followed by hydrothermal treatment in water at 200℃ for 24 h until the surface pore size reached 4 mm. Visible light treatment was simultaneously applied during the hydrothermal treatment. The goethite was then calcined at 300℃ in a 9% H2 atmosphere for 60 min, and finally coated with a 2 nm carbon layer. The visible light treatment was performed at a wavelength of 600 nm and an intensity of 75 mW / cm². 2 Irradiation under a short-arc xenon lamp with a power of 400W.

[0055] Example 15: Unlike Example 14, the modification method is as follows: goethite is ball-milled at a rate of 350 r / min for 5.5 h, then doped with 3 wt% AlCl3 solution, and then hydrothermally treated in water at 180°C for 22 h until the surface pore size is 2 mm. Visible light treatment is simultaneously applied during the hydrothermal treatment stage. Then, it is calcined at 280°C in an 8% H2 atmosphere for 45 min. Finally, a 1.5 nm carbon layer is coated on the surface of the goethite.

[0056] Example 16: Unlike Example 14, the modification method is as follows: goethite is ball-milled at a rate of 450 r / min for 6.5 h, then mixed with 5 wt% AlCl3 solution, and then hydrothermally treated in water at 220°C for 26 h until the surface pore size is 5 mm. Visible light treatment is simultaneously applied during the hydrothermal treatment stage. Then, it is calcined at 320°C in a 10% H2 atmosphere for 75 min. Finally, a 2.5 nm carbon layer is coated on the surface of the goethite.

[0057] Example 17: Unlike Example 14, the visible light processing method is as follows: at a wavelength of 420 nm and an intensity of 50 mW / cm². 2 Irradiation under a short-arc xenon lamp with a power of 300W.

[0058] Example 18: Unlike Example 14, the visible light processing method is as follows: at a wavelength of 800 nm and an intensity of 100 mW / cm². 2 Irradiation under a 500W short-arc xenon lamp.

[0059] Example 19: Unlike Example 14, the carbon layer includes, from the inside out: a substrate layer, an intermediate transition layer, and a functional layer;

[0060] The carbon layer was prepared by immersing calcined goethite in a citrate buffer solution with pH=4 at a solid-liquid ratio of 1g:6mL to obtain an iron-rich oxide layer. Then, it was immersed in a glucose solution with a concentration of 11wt.% at a temperature of 175℃ until a base layer with a thickness of 1.8nm was formed on the surface, which was denoted as the carbon substrate layer.

[0061] Nitrogen-doped graphene with an N:C mass ratio of 7:100 was then deposited on the surface of the substrate layer using CVD, with a deposition thickness of 0.4 nm. Subsequently, a 4.5% protective atmosphere was introduced, and the temperature was increased to 300 °C at a rate of 8 °C / min and held for 25 min to obtain an intermediate transition layer. The protective atmosphere was obtained by mixing H2 and Ar in a 1:1 volume ratio.

[0062] Then, the surface of the intermediate transition layer was subjected to argon plasma bombardment treatment at a substrate temperature of 150℃, a power of 145W, and a working pressure of 0.5Pa for 9 minutes. Following this, Fe and carbon targets were co-deposited using magnetron sputtering. Finally, the magnetron-sputtered material was immersed in an ethylene glycol solution containing FeSO4, ultrasonicated, and then dried under nitrogen protection to obtain a functional layer with a thickness of 0.9 nm. The molar concentration of FeSO4 was 0.13 mol / L. During the magnetron sputtering process, the power ratio of the Fe target to the carbon target was 1:4, and the vacuum degree was 5 × 10⁻⁶. -3 The sputtering pressure was 0.9 Pa, the substrate-target distance was 90 mm, and the sputtering time was 35 min. The ultrasonic treatment was carried out at an ultrasonic frequency of 40 kHz, an ultrasonic power of 225 W, and a temperature of 28 ℃ for 27 min.

[0063] Example 20: Unlike Example 19, the carbon layer was prepared by immersing calcined goethite in a citric acid buffer solution with a solid-liquid ratio of 1g:5mL to obtain an iron-rich oxide layer. Then, it was immersed in a 10wt.% glucose solution at 170°C until a base layer with a thickness of 1.5nm was formed on the surface, which was denoted as the carbon substrate layer.

[0064] Example 21: Unlike Example 19, the carbon layer was prepared by immersing calcined goethite in a citric acid buffer solution with a solid-liquid ratio of 1g:7mL to obtain an iron-rich oxide layer. Then, it was immersed in a glucose solution with a concentration of 12wt.% at a temperature of 180℃ until a base layer with a thickness of 2nm was formed on the surface, which was denoted as the carbon substrate layer.

[0065] Example 22: Unlike Example 19, nitrogen-doped graphene with an N:C mass ratio of 5:100 was deposited on the surface of the substrate layer by CVD, with a deposition thickness of 0.3 nm. Then, a 4% protective atmosphere was introduced, and the temperature was raised to 280°C at a rate of 5°C / min and held for 20 min to obtain an intermediate transition layer.

[0066] Example 23: Unlike Example 19, nitrogen-doped graphene with an N:C mass ratio of 8:100 was deposited on the surface of the substrate layer by CVD, with a deposition thickness of 0.5 nm. Then, a 5% protective atmosphere was introduced, and the temperature was raised to 320°C at a rate of 10°C / min and held for 30 min to obtain an intermediate transition layer.

[0067] Example 24: Unlike Example 19, the intermediate transition layer surface was subjected to argon plasma bombardment treatment at a substrate temperature of 145°C, a power of 140W, and a working pressure of 0.45Pa for 8 minutes. Then, Fe and carbon targets were co-deposited by magnetron sputtering. Finally, the magnetron sputtered material was immersed in an ethylene glycol solution containing FeSO4, ultrasonicated, and dried under nitrogen protection to obtain a functional layer with a thickness of 0.8 nm.

[0068] Example 25: Unlike Example 19, the intermediate transition layer surface was subjected to argon plasma bombardment treatment at a substrate temperature of 155°C, a power of 150W, and a working pressure of 0.55Pa for 10 minutes. Then, Fe and carbon targets were co-deposited by magnetron sputtering. Finally, the magnetron sputtered material was immersed in an ethylene glycol solution containing FeSO4, ultrasonicated, and dried under nitrogen protection to obtain a functional layer with a thickness of 1 nm.

[0069] Example 26: Unlike Example 19, the molar concentration of FeSO4 was 0.1 mol / L; during magnetron sputtering, the power ratio of Fe target to carbon target was 1:3, the vacuum degree was 5×10-3 Pa, the sputtering pressure was 0.8 Pa, the substrate-target distance was 80 mm, and the sputtering time was 30 min.

[0070] Example 27: Unlike Example 19, the molar concentration of FeSO4 was 0.15 mol / L; during magnetron sputtering, the power ratio of Fe target to carbon target was 1:5, the vacuum degree was 5×10-3 Pa, the sputtering pressure was 1.0 Pa, the substrate-target distance was 100 mm, and the sputtering time was 40 min.

[0071] Example 28: Unlike Example 19, the ultrasonic treatment was performed for 25 minutes at an ultrasonic frequency of 35 kHz, an ultrasonic power of 200 W, and a temperature of 25 °C.

[0072] Example 29: Unlike Example 19, the ultrasonic treatment was performed for 30 minutes at an ultrasonic frequency of 45 kHz, an ultrasonic power of 250 W, and a temperature of 30 °C.

[0073] Example 30: Unlike Example 19, after nitrogen-protected drying, a 0.60 wt% KH2PO4 solution was sprayed onto the surface.

[0074] Example 31: Unlike Example 30, after nitrogen-protected drying, a 0.5 wt% KH2PO4 solution was sprayed onto the surface.

[0075] Example 32: Unlike Example 30, after nitrogen-protected drying, a 0.7wt% KH2PO4 solution was sprayed onto the surface.

[0076] Experimental example: The adsorption effect of goethite on antibiotic drug molecules and the conversion effect on As(III) were detected in Examples 1-32 and Control Group 1-Control Group respectively; the formation of Fe(II) was used as the result of the activation effect of antibiotic drug molecules on the surface of goethite; and the removal rate of As(III) was used as the result of the conversion of As(III) on the surface of goethite after tetracycline antibiotics acted on it.

[0077] The goethite treated in Examples 1-7 was analyzed, and it was found that tetracycline antibiotics do indeed have a significant activating effect on goethite and a conversion effect on trivalent arsenic, with Example 1 showing better results. The EPR spectrum of the goethite solid synthesized in Example 1 was determined, as shown... Figure 1 As shown, the spectrum exhibits a distinct Lorentz line with a resonance factor (g) of 2.02, indicating the presence of certain vacancies in our synthesized goethite. These vacancies may promote the adsorption of Fe(II) by goethite, accelerating the electron transfer process between Fe(II) and Fe(III) on the goethite surface. This leads to the rapid oxidation of adsorbed Fe(II) by Fe(III) on the goethite surface, rather than by O2. Antibiotic molecules complex and reduce Fe(III) on the goethite surface to generate Fe(II), while simultaneously undergoing their own transformation. Furthermore, it is concluded that, under the influence of oxygen vacancies on the goethite surface, reduced Fe(II) rapidly undergoes electron transfer with structural Fe(III) to generate highly reactive Fe(III), which directly oxidizes As(III). This process can occur under both anaerobic and aerobic conditions.

[0078] Control group 1: Unlike Example 1, in S2, the tetracycline antibiotic was norfloxacin.

[0079] Control group 2: Unlike Example 1, in S2, the tetracycline antibiotic was ciprofloxacin.

[0080] Comparison of Examples 1, 8-13, and Control Groups 1-2, and Figure 2 It was found that the choice of tetracycline antibiotics did not significantly affect the promoting effect of As(III) conversion. The difference in molecular structure among the three TCs lies in the different substituents at the C5 and C7 positions on the B and D rings. However, the possible binding sites of OTCs to Fe(III) on the CFH surface are the N atom of the -C(O)NH2 group, the O atom of the -OH group, or the N atom of the -N(CH3)2 group on the A ring. Therefore, the difference in substituents on the B and D rings has almost no effect on the reaction between CFH and TCs. In addition, two commonly used sulfonamide antibiotics (sulfamethoxazole SNM and sulfamethoxazole SMX), two quinolone antibiotics (norfloxacin NOR and ciprofloxacin CIP) and an aminoglycoside antibiotic (gentamicin GEN) were selected. SNM, SMX, and GEN also significantly promoted the oxidation of As(III) by CFH, with 66.9±1.2%, 54.8±3.5%, and 85.9±2.3% of As(III) being oxidized to As(V), respectively. The two quinolone antibiotics in control groups 1 and 2 had relatively weak effects, with As(III) conversion rates of 30.7±5.8% and 26.4±2.9%, respectively.

[0081] 1. Investigate the effects of visible light treatment on the adsorption rate of tetracycline antibiotics and the oxidation rate of trivalent arsenic in goethite.

[0082] Control group 3: Unlike Example 14, no visible light-assisted treatment was performed during the modification process.

[0083] Table 1 Comparison of Example 1, Examples 14-18 and Comparative Example 3

[0084]

[0085]

[0086] A comparison of Examples 1 and 14-18 shows that modification of goethite effectively improves the adsorption rate of antibiotic molecules and the oxidation rate of trivalent arsenic in goethite. This is because ball milling increases surface defect sites and enhances adsorption activity. AlCl3 doping can utilize Al... 3+ Partial Fe Substitution 3+ This enhances surface acidity and promotes As(III) adsorption and oxidation. Hydrothermal + visible light treatment can excite the semiconductor properties of goethite, generating electrons (e... - ) and holes (h +The pre-activated surface Fe(III) is converted to Fe(II), improving subsequent catalytic efficiency; H2 calcination can partially reduce Fe(III) to Fe(II), forming oxygen vacancies and enhancing As(III) adsorption and electron transfer. Carbon coating plays a role in protecting the active sites.

[0087] Comparing Examples 14-18 and Control Group 3 (without visible light treatment), it can be seen that the absence of visible light treatment significantly reduces the adsorption rate of antibiotic drug molecules and the oxidation efficiency of As(III) in goethite, as it reduces the formation of Fe(II). Visible light can excite the semiconductor properties of goethite, causing it to generate electrons (e... - ) and holes (h + Pre-activated surface Fe(III) is converted to Fe(II), which improves subsequent catalytic efficiency; and there is no negative impact of visible light: the adsorption rate of antibiotic drug molecules decreases: due to the lack of photogenerated electrons, Fe(III) is reduced to Fe(II), and the conversion rate of As(III) decreases: the oxidation of As(III) depends on Fe(II) / ·OH, and if Fe(II) is not generated enough, the conversion rate decreases.

[0088] 2. Investigate the effect of carbon layer preparation methods on the adsorption rate of antibiotic drug molecules and the oxidation rate of trivalent arsenic in goethite.

[0089] Control group 4: Unlike Example 19, no argon plasma bombardment treatment was performed between the intermediate transition layer and the functional layer.

[0090] Table 2 Comparison of Examples 14, 19-32 and Comparative Example 4

[0091]

[0092] A comparison of Examples 14 and 19-29 shows that the carbon layers prepared by specific methods in Examples 19-29 can effectively improve the adsorption rate of antibiotic molecules and the oxidation rate of trivalent arsenic by goethite compared to the conventional carbon layer in Example 14. This is because the hierarchical porous structure of the carbon layer can provide more diffusion channels for tetracycline antibiotics, shortening the adsorption equilibrium time. Furthermore, the Fe-OC bonds generated on the surface can enhance the coordination adsorption of antibiotic molecules through the chemical bonding between the carbon layer and goethite. In addition, nitrogen-doped graphene and Fe nanoparticles synergistically promote electron transfer. The As(III) oxidation pathway includes two types: direct electron transfer: As(III) + Fe(II) → As(V) + Fe(III) and free radical oxidation: As(III) + ·OH (in-situ generation) → As(V) + H2O, thus improving the conversion rate.

[0093] The comparison between Examples 19-29 and Control Group 4 shows that the absence of argon plasma bombardment between the intermediate transition layer and the functional layer affects the adsorption rate of goethite on antibiotic drug molecules and the oxidation rate of trivalent arsenic. This is because argon plasma bombardment can etch the carbon layer to form micropores, exposing more Fe active sites, thereby improving the adsorption rate of goethite on antibiotic drug molecules and the oxidation rate of trivalent arsenic.

[0094] Comparing Examples 19 and 30-32, it can be seen that the addition of KH2PO4 solution can affect the adsorption rate of antibiotic drug molecules and the oxidation rate of trivalent arsenic by goethite. This is because KH2PO4 solution can effectively increase the adsorption capacity of As by increasing the surface phosphate groups. Therefore, considering all factors, Example 30 is the optimal solution.

Claims

1. A method for activating goethite-based minerals to promote As oxidation using antibiotic drug molecules, characterized in that, Includes the following steps: S1, Preparation of goethite Take 80-100 mL of 5 mol / L KOH solution and add it to 180-200 mL of 1 mol / L Fe(NO3)3 solution. Then dilute the mixed solution to 2 L with ultrapure water and seal it. Aging at 65-75℃ for 55-65 h, the precipitate turns yellowish-brown to obtain the synthetic mineral. Then centrifuge the synthetic mineral at 7500-8500 rpm, separate the solid and wash it with ultrapure water 5-8 times. After freeze drying and grinding, store it at 3-5℃ to obtain goethite. S2, antibiotic-activated goethite and As oxidation The pH of a solution containing antibiotic molecules and trivalent arsenic is adjusted to 5.5-6.5, goethite is added, and the reaction is carried out in the dark at 23-27℃ and 150-190 rpm for 2-72 hours to activate the goethite by the antibiotic molecules and further complete the oxidation of As. The concentration of the antibiotic molecules in the solution is 45-55 μM, the concentration of trivalent arsenic is 2.67 μM, and the ratio of goethite to the solution to be treated is 30-50 mg: 20 ml. It also includes: modifying the goethite prepared by S1; The modification process is as follows: goethite is ball-milled at a rate of 350-450 r / min for 5.5-6.5 h, then mixed with 3-5 wt% AlCl3 solution, followed by hydrothermal treatment in water at 180-220℃ for 22-26 h until the surface pore size is 2-5 mm. Visible light treatment is applied simultaneously during the hydrothermal treatment stage. Then, it is calcined at 280-320℃ in an 8-10% H2 atmosphere for 45-75 min. Finally, a carbon layer of 1.5-2.5 nm is coated on the surface of the goethite. The visible light processing method is as follows: the wavelength is 420-800nm ​​and the intensity is 50-100mW / cm. 2 Irradiation under a short-arc xenon lamp with a power of 300-500W; The carbon layer comprises, from the inside out, a substrate layer, an intermediate transition layer, and a functional layer; The carbon layer is prepared by immersing calcined goethite in a citrate buffer solution with pH=4 at a solid-liquid ratio of 1g:5-7mL to obtain an iron-rich oxide layer. Then, it is immersed in a glucose solution with a concentration of 10-12wt.% at a temperature of 170-180℃ until a base layer with a thickness of 1.5-2nm is formed on the surface, which is referred to as the carbon substrate layer. Nitrogen-doped graphene with an N:C mass ratio of 5-8:100 is deposited on the surface of the substrate layer by CVD, with a deposition thickness of 0.3-0.5 nm. Then, a protective atmosphere of 4-5% is introduced, and the temperature is raised to 280-320°C at a heating rate of 5-10°C / min and held for 20-30 min to obtain an intermediate transition layer. Then, the surface of the intermediate transition layer is subjected to argon plasma bombardment treatment at a substrate temperature of 145-155℃, a power of 140-150W, and a working pressure of 0.45-0.55Pa for 8-10 minutes. Then, Fe and carbon targets are co-deposited by magnetron sputtering. Finally, the magnetron sputtered material is immersed in an ethylene glycol solution containing FeSO4, ultrasonically treated, and dried under nitrogen protection to obtain a functional layer with a thickness of 0.8-1nm; the molar concentration of FeSO4 is 0.1-0.15mol / L.

2. The method for activating goethite to promote As oxidation as described in claim 1, characterized in that, In S2, the antibiotic drug molecule is any one of gentamicin, oxytetracycline, tetracycline, chlortetracycline, sulfonamide, or sulfamethoxazole.

3. The method for activating goethite to promote As oxidation as described in claim 1, characterized in that, The protective atmosphere is obtained by mixing H2 and Ar in equal volume ratio.

4. The method for activating goethite to promote As oxidation as described in claim 1, characterized in that, During magnetron sputtering, the power ratio of the Fe target to the carbon target is 1:3-5, and the vacuum level is ≤5×10⁻⁶. -3 The sputtering pressure is 0.8-1.0 Pa, the substrate-target distance is 80-100 mm, and the sputtering time is 30-40 min.

5. The method for activating goethite to promote As oxidation as described in claim 1, characterized in that, The ultrasonic treatment is performed for 25-30 minutes at an ultrasonic frequency of 35-45kHz, an ultrasonic power of 200-250W, and a temperature of 25-30℃.

6. The method for activating goethite to promote As oxidation as described in claim 1, characterized in that, After nitrogen-protected drying, spray the surface with a 0.5-0.7 wt% KH2PO4 solution.

7. The method for activating goethite to promote As oxidation as described in claim 1, characterized in that, In S2, the activation of goethite by antibiotic drug molecules can occur under both anaerobic and aerobic conditions.

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