A visible light responsive photocatalyst capable of activating persulfate and its preparation and application

Abstract

The present invention discloses a visible light responsive photocatalyst capable of activating persulfate, and its preparation and application. The photocatalyst is added to a high-salt wastewater system containing antibiotic pollutants. After adsorption equilibrium is achieved in the dark under a water bath at 20-35°C, persulfate is added, and the antibiotic pollutants in the high-salt wastewater system are synergistically removed under visible light illumination. The photocatalyst is an Ag-doped asymmetric mesoporous TiO2 catalyst. The present invention deposits Ag inside the novel spirally stacked asymmetric TiO2 pores to obtain a composite catalyst with visible light response, and due to the Ti in the composite catalyst, the 3+ / Ti 4+ There is a coupling system that can effectively activate persulfate and utilize photocatalysis and persulfate activation to form abundant active groups such as photogenerated holes, sulfate radicals and hydroxyl radicals, which effectively improves the removal effect of the catalyst on ofloxacin antibiotics in the wastewater system.

Description

Technical Field

[0001] The invention relates to a method for degrading antibiotics in an environment, and in particular to a visible light responsive photocatalyst capable of activating persulfate, a preparation method thereof, and an application thereof in degrading antibiotics. Background Art

[0002] In recent years, the environmental pollution caused by the overuse of antibiotics, including ofloxacin and other quinolones, has attracted significant attention. Antibiotic residues in wastewater not only promote microbial resistance but also pose significant risks to ecosystems and human health. Therefore, the deep treatment of wastewater containing trace amounts of antibiotics to minimize their impact on ecosystems is a current research hotspot.

[0003] Among the many deep treatment technologies, advanced oxidation methods are considered to be one of the most promising methods in recent years. It is based on the generation of highly active free radicals that can completely mineralize trace antibiotics in water bodies. Heterogeneous photocatalysis is one of the most widely studied and applied advanced oxidation technologies. Under light excitation, photocatalysts such as TiO2 can generate photogenerated holes and electrons. In the process, not only do the photogenerated holes directly mineralize and degrade pollutants, but hydroxyl radicals and superoxide radicals are also generated in the system, which can also participate in the degradation reaction of organic pollutants such as antibiotics. However, because it is difficult for photocatalytic materials to completely overcome the defects of photogenerated holes and electrons, the number of active free radicals generated in the process is relatively small, and the degradation effect on pollutants such as antibiotics in water bodies is generally average.

[0004] In recent years, persulfate systems, such as peroxydisulfate (PDS) and peroxymonosulfate (PMS), have gained widespread application in advanced wastewater treatment due to their abundant reactive free radicals. However, the sulfate and hydroxyl radicals generated in these systems are less oxidative than the photogenerated holes produced during photocatalysis, and their ability to degrade antibiotics is not outstanding. Furthermore, catalysts used for persulfate activation often utilize Mn-, Fe-, or Co-based oxides, which can cause secondary pollution when added to water bodies. Summary of the Invention

[0005] The present invention deposits Ag inside the novel spiral stacked asymmetric TiO2 pores to obtain a composite catalyst with visible light response, and because the Ti in the composite catalyst 3+ / Ti 4+ There is a coupling system that can effectively activate persulfate and utilize photocatalysis and persulfate activation to form abundant active groups such as photogenerated holes, sulfate radicals and hydroxyl radicals, which effectively improves the removal effect of the catalyst on ofloxacin antibiotics in the wastewater system.

[0006] A method for degrading antibiotics in a high-salinity wastewater system using a combination of photocatalysis and persulfate, comprising:

[0007] A photocatalyst is added to a high-salt wastewater system containing antibiotic pollutants. After adsorption equilibrium is achieved in the dark under water bath conditions of 20-35°C, persulfate is added, and the antibiotic pollutants in the high-salt wastewater system are synergistically removed under visible light irradiation. The photocatalyst is an Ag-doped asymmetric mesoporous TiO2 catalyst.

[0008] The collaborative processing principle of the present invention

[0009] First, the composite photocatalyst generates photogenerated holes and electrons under visible light excitation:

[0010] Visible light + TiO2 → h + +e -

[0011] The photogenerated electrons are then captured by persulfate, activating the persulfate:

[0012] e - +S2O8 2- →SO4 ·- +SO4 2-

[0013] In addition, due to its asymmetry, the mesoporous TiO2 with spiral stacking structure contains Ti 3+ / Ti 4+ Yes, this catalyst can also activate persulfate to produce sulfate radicals and hydroxyl radicals at the same time:

[0014] Ti 3+ +S2O8 2- →Ti 4+ +SO4· - +SO4 2- (1)

[0015] SO4· - +H2O→SO4 2- +·OH(2)

[0016] Ti 4+ +e - →Ti 3+

[0017] After Ag deposition, its plasmon resonance effect can make the TiO2 composite catalyst responsive to visible light. Under visible light excitation, the photogenerated electrons generated by the spirally stacked mesoporous TiO2 are rapidly transferred to the Ag particles, promoting the effective separation of photogenerated holes and electrons, thereby generating more and more stable photogenerated holes. In addition, sodium persulfate (PDS) also consumes photogenerated electrons during the activation process, thereby more effectively promoting the separation of photogenerated holes and electrons, leading to a further increase in the number of photogenerated holes in the photocatalytically coupled persulfate system. Therefore, this photocatalytically coupled system can not only generate a large number of sulfate radicals and hydroxyl radicals, but also a rich supply of photogenerated holes, ensuring its effective removal rate of ofloxacin antibiotics in high-content wastewater systems.

[0018] Optionally, the Ag doping amount in the Ag-doped asymmetric mesoporous TiO2 catalyst is 1-3% by mass. Most preferably, the Ag doping amount in the Ag-doped asymmetric mesoporous TiO2 catalyst is 2% by mass. The doping amount herein can be understood as the Ag doping amount in the Ag-doped asymmetric mesoporous TiO2 catalyst being 1-3% by mass.

[0019] Optionally, the preparation method of the Ag-doped asymmetric mesoporous TiO2 catalyst includes:

[0020] (1) adding a chiral mesoporous TiO2 material having a spiral stacking structure to a reaction system containing anhydrous ethanol, deionized water, and NaOH, and stirring at a constant temperature until adsorption equilibrium is obtained to obtain an equilibrium system;

[0021] (2) filtering the equilibrium system (to remove residual NaOH in the solution), taking the filter cake and redispersing it in anhydrous ethanol to obtain a suspension system;

[0022] (3) adding an ethanol solution containing Ag ions to the suspension system for reaction. During the reaction process of this step: Ag ions diffuse into the NaOH-rich adsorption water layer on the inner surface of the mesoporous TiO2 and first react to form Ag2O. Then, under the alkaline conditions of the adsorption water layer on the inner surface of the mesoporous TiO2, they are reduced by ethanol to form elemental Ag.

[0023] (4) heat-treating the entire reaction system after the reaction in step (3);

[0024] (5) After the heat treatment, the product is cooled, separated, washed and dried in sequence.

[0025] In step (1) of the preparation method:

[0026] Optionally, the added amount of the chiral mesoporous TiO2 material having a spiral stacking structure is 0.3 to 1.0 g / mL.

[0027] The surface of the chiral mesoporous TiO2 material with a spiral stacking structure presents a chiral asymmetric spiral structure, which is itself an existing technology. Optionally, the chiral mesoporous TiO2 material with a spiral stacking structure can be prepared with reference to the literature "Fu Xiaohang, Wang Linxiang, Li Yao, et al. 2021. Visible light responsive chiral TiO2 composite photocatalyst and its degradation of organic pollutants [J]. Journal of Environmental Sciences, 41(12): 48624870".

[0028] Optionally, the ratio of anhydrous ethanol, deionized water and NaOH is 200 ml: 1-2 ml: 5-5.5 mg; more preferably, it is 200 ml: 1.5 ml: 5.062 mg.

[0029] Optionally, the time required to reach adsorption equilibrium is 3 to 5 hours.

[0030] Optionally, after the photocatalyst is added to a high-salt wastewater system containing antibiotic pollutants, adsorption equilibrium is achieved in the dark under a water bath at 30° C. The adsorption equilibrium can be understood as a state in which the concentration of the pollutants does not decrease significantly.

[0031] In step (3) of the preparation method:

[0032] Optionally, the concentration of the suspension system is 0.0025 g / mL; the concentration of Ag ions in the ethanol solution containing Ag ions is 0.1-0.6 mg / mL; and the volume ratio of the ethanol solution containing Ag ions to the suspension system is 0.05-0.5.

[0033] Optionally, the ethanol solution containing Ag ions can be obtained by dissolving silver nitrate in anhydrous ethanol.

[0034] In step (4) of the preparation method:

[0035] Optionally, the heat treatment temperature is 160-180° C. and the heat treatment time is 3-8 hours.

[0036] In step (5) of the preparation method:

[0037] Optionally, the system is cooled to room temperature, filtered and separated, washed with deionized water until the filtrate is neutral, and the powder is vacuum-dried at room temperature to obtain the Ag-doped asymmetric mesoporous TiO2 catalyst.

[0038] Optionally, the dosage of the Ag-doped asymmetric mesoporous TiO2 catalyst is 1.25 to 5.0 g / mL; most preferably 5.0 mg / mL.

[0039] Optionally, the salt component in the high-salt wastewater system is NaCl, Na2SO4, KCl, or a mixture of multiple salt components; the salt concentration is 5-10%. The salt concentration here can be understood as the mass percentage of the salt component in the high-salt wastewater system.

[0040] Optionally, the antibiotic pollutants in the high-salt wastewater system are quinolone antibiotics.

[0041] Optionally, the concentration of the antibiotic contaminant is 5 to 50 mg / L.

[0042] Preferably, the quinolone antibiotic is ofloxacin.

[0043] Optionally, the added amount of the persulfate is 0.075-0.225 g / L; most preferably 0.15 g / L.

[0044] Optionally, the persulfate is selected from sodium persulfate, potassium persulfate and ammonium persulfate.

[0045] The present invention also provides a method for preparing an Ag-doped asymmetric mesoporous TiO2 catalyst, comprising:

[0046] (1) adding a chiral mesoporous TiO2 material having a spiral stacking structure to a reaction system containing anhydrous ethanol, deionized water, and NaOH, and stirring at a constant temperature until adsorption equilibrium is obtained to obtain an equilibrium system;

[0047] (2) filtering the equilibrium system (to remove residual NaOH in the solution), taking the filter cake and redispersing it in anhydrous ethanol to obtain a suspension system;

[0048] (3) An ethanol solution containing Ag ions is added to the suspension system for reaction. During the reaction process of this step: Ag ions diffuse into the adsorbed water layer rich in NaOH on the inner surface of the mesoporous TiO2 and first react to form Ag2O, and then are reduced by ethanol under alkaline conditions to form elemental Ag;

[0049] (4) heat-treating the entire reaction system after the reaction in step (3);

[0050] (5) After the heat treatment, the product is cooled, separated, washed and dried in sequence.

[0051] More preferably, the preparation method comprises:

[0052] (1) Anhydrous ethanol, deionized water, and NaOH were mixed in a three-necked flask to form a homogeneous system;

[0053] (2) adding a chiral mesoporous TiO2 material having a spiral stacking structure to the system obtained in step (1), and adsorbing the material by stirring at a constant temperature for 4 hours until adsorption equilibrium is reached;

[0054] (3) filtering the adsorption equilibrium system obtained in step (2) to remove residual NaOH in the solution, and then redispersing the filter cake in anhydrous ethanol solution and stirring and dispersing to re-form a stable suspension system;

[0055] (4) dissolving silver nitrate in ethanol and adding it dropwise to the suspension system obtained in step (3) for reaction, wherein the Ag ions in the system diffuse into the adsorbed water layer rich in NaOH on the inner surface of the mesoporous TiO2, first reacting to form Ag2O, and then being reduced by ethanol under alkaline conditions to form elemental Ag;

[0056] (5) After the reaction of step (4) is completed, the entire reaction solution system is transferred to a polytetrafluoroethylene beaker, and then the beaker is placed in a sealed reactor and reacted at 160-180°C;

[0057] (6) The system in step (5) is reacted for 3 to 8 hours and then cooled to room temperature. The system is filtered and separated, and washed with deionized water until the filtrate is neutral. The powder is vacuum-dried at room temperature to obtain the Ag-doped asymmetric mesoporous TiO2 catalyst.

[0058] The present invention also provides an Ag-doped asymmetric mesoporous TiO2 catalyst prepared by a preparation method.

[0059] The preparation method of the catalyst of the present invention is simple. In the Ag-TiO2 composite material obtained by the present invention, Ag can be deposited on the inner surface of the asymmetric mesopores with spiral stacking. The Ag deposition and the chiral asymmetric structure of TiO2 allow a large amount of Ti to be formed in the catalyst. 3+ The composite catalyst exhibits both visible light response and catalytic activity, and both Ag deposition and spiral stacking asymmetric pore structures are controllable. The composite photocatalyst can be efficiently degraded and removed from high-salinity wastewater by coupling visible light excitation with persulfate activation.

[0060] Compared with the prior art, the preparation method of the visible light responsive Ag-doped asymmetric mesoporous TiO2 catalyst capable of activating persulfate and the synergistic photocatalytic degradation of antibiotics in a high-salt wastewater system by persulfate catalytic oxidation provided by the present invention have at least one of the following beneficial effects:

[0061] 1) The preparation method is simple, easy to operate, and low in cost; the preparation method of the present invention can be used to easily regulate the structure, visible light response, and photodegradation performance of the composite photocatalyst by changing the reaction and heat treatment conditions.

[0062] 2) Ag deposition allows the electrons generated by TiO2 after light excitation to be transferred to Ag particles, promoting the effective separation of photogenerated holes and electrons, thereby generating more and more stable photogenerated holes.

[0063] 3) In the reaction system, the amount of photocatalyst added is limited, so the number of photogenerated electrons and holes that can be generated by chiral mesoporous TiO2 is limited. Sodium persulfate (PDS) photogenerated electron acceptor is selected, which has relatively stable properties and produces strong oxidizing free radicals after being excited. PDS will compete for the photogenerated electrons generated by visible light excitation, further improving the separation rate of holes and electrons in photocatalysis, and further increasing the number of photogenerated holes in the active components.

[0064] 4) The product of the reaction between the free radicals activated by PDS and organic matter is sulfate ions, which will not cause serious secondary pollution to the high-salt wastewater environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 The removal rates of ofloxacin (5.0 mg / L) in the wastewater system of Control Examples 1 to 5 (reaction time 5 hours).

[0066] Figure 2 These are transmission electron microscope (TEM) photos of the visible light responsive Ag-TiO2 composite photocatalysts with spiral stacking structures prepared in Examples 1 to 3 of the present invention.

[0067] Figure 3 These are X-ray photoelectron spectroscopy (XPS) graphs of the visible light responsive Ag-TiO2 composite photocatalysts with spiral stacking structures prepared in Examples 1 to 3 of the present invention.

[0068] Figure 4 These are the X-ray diffraction (XRD) patterns of the visible light responsive Ag-TiO2 composite photocatalysts with spiral stacking structures prepared in Examples 1 to 3 of the present invention.

[0069] Figure 5 The removal rate of ofloxacin (5.0 mg / L) in the wastewater system under visible light excitation by the visible light responsive Ag-TiO2 composite photocatalyst with a spiral stacking structure prepared in Examples 1 to 3 of the present invention (reaction time: 5 hours). DETAILED DESCRIPTION

[0070] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0071] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0072] The following specific examples further illustrate how the present invention prepares a visible-light-responsive Ag-doped asymmetric mesoporous TiO2 catalyst capable of persulfate activation and characterize its performance. For comparison, the degradation of ofloxacin using chiral mesoporous TiO2 is reported as Control Example 1; direct photodegradation of ofloxacin using Ag-doped chiral mesoporous TiO2 under visible light excitation is reported as Control Example 2; degradation of ofloxacin by persulfate-activated oxidation under visible light is reported as Control Example 3; and degradation of ofloxacin using achiral mesoporous TiO2 as a catalyst coupled with persulfate-catalyzed oxidation and photocatalytic degradation is reported as Control Example 4. The degradation of ofloxacin using achiral mesoporous TiO2 under light irradiation is reported as Control Example 5.

[0073] Figure 1 The removal rate of ofloxacin (5.0 mg / L) in the wastewater system under visible light excitation is shown as a control example (reaction time 5 hours).

[0074] The visible light responsive chiral TiO2 photocatalyst with a spiral stacking structure used in the following examples and control examples was prepared with reference to the literature "Fu Xiaohang, Wang Linxiang, Li Yao, et al. 2021. Visible light responsive chiral TiO2 composite photocatalyst and its degradation of organic pollutants [J]. Journal of Environmental Sciences, 41(12): 48624870".

[0075] A specific preparation process is as follows:

[0076] The chiral mesoporous TiO2 photocatalyst was prepared by self-assembly using the D-chiral surfactant C14-D-AlaA as a soft template. The following are the optimal experimental conditions and reagent ratios obtained by the research team: 0.3g of chiral surfactant C14-D-AlaA was weighed and dissolved in 10.0ml of deionized water and 10.0ml of sodium hydroxide (0.1mol·L -1 ) in a mixed solution and stirred at 600 rpm for 10 min to form a uniformly dispersed sol; then 10.0 ml of hydrobromic acid (0.1 mol·L -1), maintain the speed and continue stirring for 1 hour. Then add 0.25ml of structure directing agent TMAPS and 2.92ml of tetrabutyl titanate to the system and stir for 2 hours. The above processes are all carried out at a constant temperature of 20°C. After sufficient stirring, the sol is placed in a 0°C environment for aging for 24 hours. After washing and drying, the sample is placed in a muffle furnace and calcined at 600°C for 1 hour to obtain a D-type chiral mesoporous TiO2 photocatalyst, that is, the self-made spiral stacking structure mesoporous TiO2 material described in the following control example and Examples 1 to 3.

[0077] In control example 1, chiral mesoporous TiO2 was used to degrade ofloxacin under light.

[0078] Weigh 2.0g of a spiral stacked visible light responsive chiral TiO2 photocatalyst and mix it evenly in 400mL of a wastewater system containing ofloxacin (ofloxacin concentration is about 5.0mg / L, containing magnesium ions, sodium ions, calcium ions, sulfate ions, and chloride ions; the concentrations are 0.115mol / L, 0.483mol / L, 0.014mol / L, 0.028mol / L, and 0.685mol / L, respectively). Place it in a reactor with magnetic stirring, control the water bath temperature to 30°C, and turn off the lights for 0.5 hours of adsorption. After adsorption equilibrium, irradiate the reactor under a visible light source (20W LED white light lamp: with a filter, the light intensity is 10mW / cm 2 ), samples were taken at one-hour intervals during the reaction (until 5 h of reaction), and the supernatant was collected for centrifugation. The absorbance of ofloxacin was measured using a TU-19 series UV-visible spectrophotometer (Beijing Puxi General Instrument Co., Ltd., measuring wavelength 358 nm) to determine its concentration change.

[0079] Figure 1 The removal rate of ofloxacin (5.0 mg / L) in the wastewater system is shown in the control example (reaction time 5 hours).

[0080] In control example 2, Ag-doped chiral mesoporous TiO2 composite catalyst was used to degrade ofloxacin in the absence of light.

[0081] 2.0 g of a visible light responsive Ag-mesoporous TiO composite catalyst with a spiral stacking structure (prepared as in Example 2) was weighed and uniformly mixed in 400 mL of a wastewater system containing ofloxacin (the concentration of ofloxacin was about 5.0 mg / L, and the catalyst contained magnesium ions, sodium ions, calcium ions, sulfate radicals, and chloride ions; the concentrations were 0.115 mol / L, 0.483 mol / L, 0.014 mol / L, 0.028 mol / L, and 0.685 mol / L, respectively). The catalyst was placed in a reactor with magnetic stirring, the water bath temperature was controlled to 30° C., and the reaction was carried out in the dark. Samples were taken at intervals of one hour during the reaction (until the reaction lasted 5 h), and the catalyst was centrifuged. The supernatant was taken and the absorbance of ofloxacin was measured using a TU-19 series UV-visible spectrophotometer (Beijing Puxi General Instrument Co., Ltd., measuring at a wavelength of 358 nm).

[0082] Figure 1 The removal rate of ofloxacin (5.0 mg / L) in the wastewater system is shown in the control example (reaction time 5 hours).

[0083] Comparative Example 3: Persulfate activated oxidative degradation of ofloxacin under visible light.

[0084] Weigh 0.06g of persulfate and mix it evenly in 400mL of wastewater system containing ofloxacin (the concentration of ofloxacin is about 5.0mg / L, and the concentrations of magnesium ions, sodium ions, calcium ions, sulfate ions, and chloride ions are 0.115mol / L, 0.483mol / L, 0.014mol / L, 0.028mol / L, and 0.685mol / L, respectively). Place it in a reactor with magnetic stirring, control the water bath temperature to 30℃, and adsorb for 0.5 hours with the lights off at 22℃. After adsorption equilibrium, irradiate under visible light (20W LED white light lamp with filter, light intensity of 10mW / cm 2 ), samples were taken at one-hour intervals during the reaction (until 5 h of reaction), and the supernatant was collected for centrifugation. The absorbance of ofloxacin was measured using a TU-19 series UV-visible spectrophotometer (Beijing Puxi General Instrument Co., Ltd., measuring wavelength 358 nm) to determine its concentration change.

[0085] Figure 1 The removal rate of ofloxacin (5.0 mg / L) in the wastewater system is shown in the control example (reaction time 5 hours).

[0086] Comparative Example 4 used achiral mesoporous TiO2 as a catalyst and persulfate catalytic oxidation coupled with photocatalytic degradation of ofloxacin.

[0087] 2.0 g of achiral mesoporous TiO2 photocatalyst (Zhu HW, Shang YS, Jing YK, et al. Synthesis of monodisperse mesoporous TiO2 nanospheres from a simple double-surfactant assembly-directed method for lithium storage[J]. ACS Applied Materials & Interfaces, 2016, 8: 25586-25594.) and 0.06 g of persulfate were weighed and uniformly mixed in 400 mL of a wastewater system containing ofloxacin (the concentration of ofloxacin was about 5.0 mg / L, and the concentrations of magnesium ions, sodium ions, calcium ions, sulfate ions, and chloride ions were 0.115 mol / L, 0.483 mol / L, 0.014 mol / L, 0.028 mol / L, and 0.685 mol / L, respectively). The mixture was placed in a reactor with magnetic stirring, the water bath temperature was controlled at 30°C, and the lights were turned off for adsorption for 0.5 h. After adsorption equilibrium, the visible light source (20W LED white light with filter, light intensity of 10mW / cm 2 ), samples were taken at one-hour intervals during the reaction (until 5 h of reaction), and the supernatant was collected for centrifugation. The absorbance of ofloxacin was measured using a TU-19 series UV-visible spectrophotometer (Beijing Puxi General Instrument Co., Ltd., measuring wavelength 358 nm) to determine its concentration change.

[0088] Figure 1 The removal rate of ofloxacin (5.0 mg / L) in the wastewater system is shown in the control example (reaction time 5 hours).

[0089] In Control Example 5, achiral mesoporous TiO2 was used to degrade ofloxacin under light.

[0090] Weigh 2.0g of achiral mesoporous TiO2 photocatalyst (same as control example 4), evenly mix it in 400mL of wastewater system containing ofloxacin (ofloxacin concentration is about 5.0mg / L, containing magnesium ions, sodium ions, calcium ions, sulfate, chloride ions; concentrations are 0.115mol / L, 0.483mol / L, 0.014mol / L, 0.028mol / L, 0.685mol / L respectively), place it in a reactor with magnetic stirring, control the water bath temperature to 30℃, turn off the lights and adsorb for 0.5 hours. After adsorption equilibrium, under visible light irradiation (20W LED white light lamp: with filter, light intensity is 10mW / cm 2), samples were taken at one-hour intervals during the reaction (until 5 h of reaction), and the supernatant was collected for centrifugation. The absorbance of ofloxacin was measured using a TU-19 series UV-visible spectrophotometer (Beijing Puxi General Instrument Co., Ltd., measuring wavelength 358 nm) to determine its concentration change.

[0091] Figure 1 The removal rate of ofloxacin (5.0 mg / L) in the wastewater system under visible light excitation is shown as a control example (reaction time 5 hours).

[0092] Example 1

[0093] (1) Catalyst preparation:

[0094] (1) Anhydrous ethanol, deionized water and NaOH were mixed in a three-necked flask at a volume ratio of 200 ml of anhydrous ethanol, 1.5 ml of deionized water and 5.062 mg of NaOH to form a homogeneous system. Alternatively, NaOH was first prepared into a 0.1275 mol / L aqueous solution and then mixed at a volume ratio of 1:200:1.5 among NaOH solution, anhydrous ethanol and deionized water to form a homogeneous system.

[0095] (2) Add 0.5 g of self-made spiral stacking structure mesoporous TiO2 material to the system obtained in step (1), and adsorb with constant temperature stirring for 4 h until adsorption equilibrium is reached.

[0096] (3) Filter the adsorption equilibrium system obtained in step (2) to remove residual NaOH in the solution, and then redisperse the filter cake in anhydrous ethanol solution and stir and disperse to re-form a stable suspension system.

[0097] (4) Another 10.63 g of silver nitrate was dissolved in 2.53 mg of anhydrous ethanol and added dropwise to the suspension system obtained in step (3) for reaction. The Ag ions in the system diffused into the adsorbed water layer rich in NaOH on the inner surface of the mesoporous TiO2, and first reacted to form Ag2O, which was then reduced by ethanol under alkaline conditions to form elemental Ag.

[0098] (5) After 2 hours of reaction, the entire reaction solution system was transferred to a 250 mL polytetrafluoroethylene beaker, and then the beaker was placed in a sealed reactor and reacted at 170°C.

[0099] (6) After the system in step (5) is cooled to room temperature for 6 hours, the reaction system is filtered and separated, and washed with deionized water until the filtrate is neutral. The powder is vacuum-dried at room temperature to obtain a 1% Ag-doped asymmetric mesoporous TiO2 catalyst.

[0100] The transmission electron microscope (TEM) photograph of the Ag-doped chiral mesoporous TiO2 photocatalyst with a spiral stacking structure prepared in this example under visible light excitation is shown in FIG. Figure 2 As shown; the X-ray photoelectron spectroscopy (XPS) of the Ag-doped chiral mesoporous TiO2 photocatalyst under visible light excitation of the spiral stacking structure prepared in this embodiment is shown in FIG. Figure 3 As shown; The X-ray diffraction (XRD) pattern of the visible light response Ag-TiO2 composite photocatalyst with spiral stacking structure prepared in this embodiment is as shown Figure 4 shown.

[0101] Depend on Figure 2 The TEM morphology of the catalyst shows that the visible light response performance is due to the presence of a large number of obvious spiral stacking structures in the catalyst, which forms a large number of oxygen vacancies in the catalyst and makes it respond to visible light. Figure 3 XPS chemical element analysis shows that the full spectrum shows that there are five main elements in Ag-TiO2, Ti, O, C, N and Ag, indicating that Ag is successfully doped in TiO2. Figure 4 X-ray diffraction analysis shows that the wide-angle X-ray diffraction pattern shows clear diffraction peaks of anatase TiO2, with characteristic peaks at 25.37°, 37.88°, 48.12°, 53.97°, 55.10°, and 62.74°, respectively. The corresponding crystal planes of anatase TiO2 are 101, 004, 200, 105, 211, and 204, respectively. At the same time, the characteristic peaks of Ag are 38.1°, 44.2°, and 64.4°, corresponding to the 111, 200, and 220 crystal planes of Ag. However, due to the small amount of silver doping, and the close characteristic peaks of the diffraction peaks of Ag and several crystal planes of anatase TiO2, they are masked by the characteristic peaks of TiO2.

[0102] (2) Photocatalytic coupled persulfate catalytic oxidation process for removing antibiotics from high-salinity wastewater systems

[0103] Weigh 2.0g of the Ag-doped asymmetric mesoporous TiO2 catalyst prepared in this embodiment and add it to 400mL of high-salt wastewater (containing magnesium ions, sodium ions, calcium ions, sulfate radicals, and chloride ions; the concentrations are 0.115mol / L, 0.483mol / L, 0.014mol / L, 0.028mol / L, and 0.685mol / L, respectively) containing antibiotic pollutants (the concentration of ofloxacin is about 5.0mg / L). After adsorption equilibrium in the dark under 30°C water bath conditions, add 0.06g of sodium persulfate, place it in a reactor with magnetic stirring, control the water bath temperature to 20°C, turn off the lights and adsorb for 0.5 hours. After adsorption equilibrium, under visible light irradiation (20W LED white light lamp: with a filter, the light intensity is 10mW / cm 2), samples were taken at one-hour intervals during the reaction (until 5 h of reaction), and the supernatant was collected for centrifugation. The absorbance of ofloxacin was measured using a TU-19 series UV-visible spectrophotometer (Beijing Puxi General Instrument Co., Ltd., measuring wavelength 358 nm) to determine its concentration change.

[0104] The removal rate of ofloxacin (5.0 mg / L) in the wastewater system under visible light excitation of the Ag-doped chiral mesoporous TiO2 photocatalyst with a spiral stacking structure prepared in this example (reaction time 5 hours) is as follows: Figure 5 shown.

[0105] Depend on Figure 2 It can be seen that due to the obvious spiral stacking structure in the catalyst, a large number of oxygen vacancies are formed, so that the visible light responsive Ag-TiO2 composite photocatalyst with a spiral stacking structure obtained in Example 1 has obvious visible light degradation activity. Figure 5 It shows that the composite photocatalyst prepared in Example 1 has a 5-hour removal rate of about 72% for ofloxacin in wastewater under the excitation of visible light.

[0106] Example 2

[0107] (1) Catalyst preparation

[0108] (1) Anhydrous ethanol, deionized water, and NaOH were mixed in a three-necked flask at a ratio of 200 ml of anhydrous ethanol, 1.5 ml of deionized water, and 5.062 mg of NaOH to form a homogeneous system.

[0109] (2) Add 0.5 g of self-made spiral stacking structure mesoporous TiO2 material to the system obtained in step (1), and adsorb with constant temperature stirring for 4 h until adsorption equilibrium is reached.

[0110] (3) Filter the adsorption equilibrium system obtained in step (2) to remove residual NaOH in the solution, and then redisperse the filter cake in anhydrous ethanol solution and stir and disperse to re-form a stable suspension system.

[0111] (4) Another 21.26 g of silver nitrate was dissolved in 5.06 mg of ethanol and added dropwise to the suspension system obtained in step (3) for reaction. The Ag ions in the system diffused into the adsorbed water layer rich in NaOH on the inner surface of the mesoporous TiO2, and first reacted to form Ag2O, which was then reduced by ethanol under alkaline conditions to form elemental Ag.

[0112] (5) After 2 hours of reaction, the entire reaction solution was transferred to a 250 mL polytetrafluoroethylene beaker, which was then placed in a sealed reactor and reacted at 170°C.

[0113] (6) After the system in step (5) is cooled to room temperature for 6 hours, the reaction system is filtered and separated, and washed with deionized water until the filtrate is neutral. The powder is vacuum-dried at room temperature to obtain a 2% Ag-doped asymmetric mesoporous TiO2 catalyst.

[0114] The transmission electron microscope (TEM) photograph of the Ag-doped chiral mesoporous TiO2 photocatalyst with a spiral stacking structure prepared in this example under visible light excitation is shown in FIG. Figure 2 As shown; the X-ray photoelectron spectroscopy (XPS) of the Ag-doped chiral mesoporous TiO2 photocatalyst under visible light excitation of the spiral stacking structure prepared in this embodiment is shown in FIG. Figure 3 As shown; The X-ray diffraction (XRD) pattern of the visible light response Ag-TiO2 composite photocatalyst with spiral stacking structure prepared in this embodiment is as shown Figure 4 shown.

[0115] Depend on Figure 2 The TEM morphology of the catalyst shows that the visible light response performance is due to the presence of a large number of obvious spiral stacking structures in the catalyst, which forms a large number of oxygen vacancies in the catalyst and makes it respond to visible light. Figure 3 XPS chemical element analysis shows that the full spectrum shows that there are five main elements in Ag-TiO2, Ti, O, C, N and Ag, indicating that Ag is successfully doped in TiO2. Figure 4 X-ray diffraction analysis shows that the wide-angle X-ray diffraction pattern shows clear diffraction peaks of anatase TiO2, with characteristic peaks at 25.37°, 37.88°, 48.12°, 53.97°, 55.10°, and 62.74°. The corresponding crystal planes of anatase TiO2 are 101, 004, 200, 105, 211, and 204, respectively. At the same time, the characteristic peaks of Ag element are 38.1°, 44.2°, and 64.4°, corresponding to the 111, 200, and 220 crystal planes of Ag element. However, due to the small amount of silver doping, and the close characteristic peaks of the diffraction peaks of Ag element and several crystal planes of anatase TiO2, they are masked by the characteristic peaks of TiO2.

[0116] (2) Photodegradation process of wastewater containing organic dye pollutants

[0117] Weigh 2.0g of the Ag-doped asymmetric mesoporous TiO2 catalyst prepared in this embodiment and add it to 400mL of high-salt wastewater (containing magnesium ions, sodium ions, calcium ions, sulfate radicals, and chloride ions; the concentrations are 0.115mol / L, 0.483mol / L, 0.014mol / L, 0.028mol / L, and 0.685mol / L, respectively) containing antibiotic pollutants (the concentration of ofloxacin is about 5.0mg / L). After adsorption equilibrium in the dark under 30°C water bath conditions, 0.06g of sodium persulfate is added and placed in a reactor with magnetic stirring. The water bath temperature is controlled to 20°C and the light is turned off for adsorption for 0.5 hours. After adsorption equilibrium, the reaction mixture is irradiated under a visible light source (20W LED white light lamp: with a filter, the light intensity is 10mW / cm 2 ), samples were taken at one-hour intervals during the reaction (until 5 h of reaction), and the supernatant was collected for centrifugation. The absorbance of ofloxacin was measured using a TU-19 series UV-visible spectrophotometer (Beijing Puxi General Instrument Co., Ltd., measuring wavelength 358 nm) to determine its concentration change.

[0118] The removal rate of ofloxacin (5.0 mg / L) in the wastewater system under visible light excitation of the Ag-doped chiral mesoporous TiO2 photocatalyst with a spiral stacking structure prepared in this example (reaction time 5 hours) is as follows: Figure 5 shown.

[0119] Depend on Figure 2 It can be seen that since the catalyst also has an obvious spiral stacking structure, a large number of oxygen vacancies are formed in the catalyst, so that the visible light responsive Ag-TiO2 composite photocatalyst with a spiral stacking structure obtained in Example 2 also has obvious visible light degradation activity. Figure 5 The composite photocatalyst prepared in Example 2 has a 5-hour removal rate of 81.2% for ofloxacin in wastewater under the excitation of visible light. - , h + The amount of cellulose increases, thereby improving the degradation performance in the seawater system.

[0120] Example 3

[0121] (1) Catalyst preparation

[0122] (1) Anhydrous ethanol, deionized water, and NaOH were mixed in a three-necked flask at a ratio of 200 ml of anhydrous ethanol, 1.5 ml of deionized water, and 5.062 mg of NaOH to form a homogeneous system.

[0123] (2) Add 0.5 g of self-made spiral stacking structure mesoporous TiO2 material to the system obtained in step (1), and adsorb with constant temperature stirring for 4 h until adsorption equilibrium is reached.

[0124] (3) Filter the adsorption equilibrium system obtained in step (2) to remove residual NaOH in the solution, and then redisperse the filter cake in anhydrous ethanol solution and stir and disperse to re-form a stable suspension system.

[0125] (4) Another 31.89 g of silver nitrate was dissolved in 7.59 mg of ethanol and added dropwise to the suspension system obtained in step (3) for reaction. Ag ions in the system diffused into the adsorbed water layer rich in NaOH on the inner surface of the mesoporous TiO2, and first reacted to form Ag2O, which was then reduced by ethanol under alkaline conditions to form elemental Ag.

[0126] (5) After 2 hours of reaction, the entire reaction solution was transferred to a 250 mL polytetrafluoroethylene beaker, which was then placed in a sealed reactor and reacted at 170°C.

[0127] (6) After the system in step (5) was cooled to room temperature for 6 hours, the reaction system was filtered and separated, and washed with deionized water until the filtrate was neutral. The powder was vacuum dried at room temperature to obtain a 3% Ag-doped asymmetric mesoporous TiO2 catalyst.

[0128] The transmission electron microscope (TEM) photograph of the Ag-doped chiral mesoporous TiO2 photocatalyst with a spiral stacking structure prepared in this example under visible light excitation is shown in FIG. Figure 2 As shown; the X-ray photoelectron spectroscopy (XPS) of the Ag-doped chiral mesoporous TiO2 photocatalyst under visible light excitation of the spiral stacking structure prepared in this embodiment is shown in FIG. Figure 3 As shown; The X-ray diffraction (XRD) pattern of the visible light response Ag-TiO2 composite photocatalyst with spiral stacking structure prepared in this embodiment is as shown Figure 4 shown.

[0129] Depend on Figure 2 The TEM morphology of the catalyst shows that the visible light response performance is due to the presence of a large number of obvious spiral stacking structures in the catalyst, which forms a large number of oxygen vacancies in the catalyst and makes it respond to visible light. Figure 3 XPS chemical element analysis shows that the full spectrum shows that there are five main elements in Ag-TiO2, Ti, O, C, N and Ag, indicating that Ag is successfully doped in TiO2. Figure 4X-ray diffraction analysis shows that the wide-angle X-ray diffraction pattern shows clear diffraction peaks of anatase TiO2, with characteristic peaks at 25.37°, 37.88°, 48.12°, 53.97°, 55.10°, and 62.74°. The corresponding crystal planes of anatase TiO2 are 101, 004, 200, 105, 211, and 204, respectively. At the same time, the characteristic peaks of Ag element are 38.1°, 44.2°, and 64.4°, corresponding to the 111, 200, and 220 crystal planes of Ag element. However, due to the small amount of silver doping, and the close characteristic peaks of the diffraction peaks of Ag element and several crystal planes of anatase TiO2, they are masked by the characteristic peaks of TiO2.

[0130] (2) Photodegradation process of wastewater containing organic dye pollutants

[0131] Weigh 2.0g of the Ag-doped asymmetric mesoporous TiO2 catalyst prepared in this embodiment and add it to 400mL of high-salt wastewater (containing magnesium ions, sodium ions, calcium ions, sulfate radicals, and chloride ions; the concentrations are 0.115mol / L, 0.483mol / L, 0.014mol / L, 0.028mol / L, and 0.685mol / L, respectively) containing antibiotic pollutants (the concentration of ofloxacin is about 5.0mg / L). After adsorption equilibrium in the dark under 30°C water bath conditions, 0.06g of sodium persulfate is added and placed in a reactor with magnetic stirring. The water bath temperature is controlled to 20°C and the light is turned off for adsorption for 0.5 hours. After adsorption equilibrium, the reaction mixture is irradiated under a visible light source (20W LED white light lamp: with a filter, the light intensity is 10mW / cm 2 ), samples were taken at one-hour intervals during the reaction (until 5 h of reaction), and the supernatant was collected for centrifugation. The absorbance of ofloxacin was measured using a TU-19 series UV-visible spectrophotometer (Beijing Puxi General Instrument Co., Ltd., measuring wavelength 358 nm) to determine its concentration change.

[0132] The removal rate of ofloxacin (5.0 mg / L) in the wastewater system under visible light excitation of the Ag-doped chiral mesoporous TiO2 photocatalyst with a spiral stacking structure prepared in this example (reaction time 5 hours) is as follows: Figure 5 shown.

[0133] Depend on Figure 2 It can be seen that since the catalyst also has an obvious spiral stacking structure, a large number of oxygen vacancies are formed in the catalyst, so that the visible light responsive Ag-TiO2 composite photocatalyst with a spiral stacking structure obtained in Example 2 also has obvious visible light degradation activity. Figure 5The composite photocatalyst prepared in Example 2 showed a 5-hour removal rate of 75% for ofloxacin in wastewater under visible light excitation. As the Ag doping amount increased, the degradation effect was slightly reduced compared to Example 2. This may be due to the high concentration of NaOH added during the preparation process corroding the TiO2 surface, thereby destroying its crystal structure as the Ag deposition increased. It may also be due to the large amount of sodium hydroxide added during the preparation of the composite catalyst, which directly degraded the Ag in the presence of ethanol. + is reduced to Ag, thereby reducing the visible activity of the catalyst.

[0134] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A method for degrading antibiotics in a high-salt wastewater system using a combination of photocatalysis and persulfate, characterized in that: include: A photocatalyst is added to a high-salt wastewater system containing antibiotic pollutants. After adsorption equilibrium is achieved in the dark under water bath conditions of 20-35°C, persulfate is added, and the antibiotic pollutants in the high-salt wastewater system are synergistically removed under visible light irradiation. The photocatalyst is an Ag-doped asymmetric mesoporous TiO2 catalyst.

2. The method according to claim 1, characterized in that The Ag-doped asymmetric mesoporous TiO2 catalyst has an Ag doping amount of 1-3% by mass.

3. The method according to claim 1, characterized in that The preparation method of the Ag-doped asymmetric mesoporous TiO2 catalyst comprises: (1) Adding a chiral mesoporous TiO2 material having a spiral stacking structure to a reaction system containing anhydrous ethanol, deionized water, and NaOH, stirring at a constant temperature until adsorption equilibrium is obtained to obtain an equilibrium system; (2) filtering the equilibrium system, taking the filter cake and redispersing it in anhydrous ethanol to obtain a suspension system; (3) An ethanol solution containing Ag ions is added to the suspension system for reaction. During the reaction process of this step: Ag ions diffuse into the adsorbed water layer rich in NaOH on the inner surface of mesoporous TiO2 and first react to form Ag2O, and then are reduced by ethanol under alkaline conditions to form elemental Ag; (4) heat-treating the entire reaction system after the reaction in step (3); (5) After the heat treatment, the product is cooled, separated, washed and dried in sequence.

4. The method according to claim 3, characterized in that In step (1), the amount of chiral mesoporous TiO2 material having a spiral stacking structure added is 0.3~1.0g / mL.

5. The method according to claim 3, characterized in that In step (3), the concentration of the suspension system is 0.0025 g / mL; the concentration of Ag ions in the ethanol solution containing Ag ions is 0.1-0.6 mg / mL; and the volume ratio of the ethanol solution containing Ag ions to the suspension system is 0.05-0.

5.

6. The method according to claim 1, characterized in that The dosage of the Ag-doped asymmetric mesoporous TiO2 catalyst is 1.25-5.0 g / mL.

7. The method according to claim 1, characterized in that The salt concentration of the high-salt wastewater system is 5~10%; the antibiotic pollutants in the high-salt wastewater system are quinolone antibiotics; and the concentration of the antibiotic pollutants is 5~50 mg / L.

8. The method according to claim 7, characterized in that The quinolone antibiotic is ofloxacin.

9. The method according to claim 1, characterized in that The added amount of the persulfate is 0.075-0.225 g / L.

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