CN115430448A - Catalyst for activating persulfate to selectively oxidize sulfamethoxazole and its preparation and application - Google Patents

Abstract

The invention relates to a catalyst for efficiently activating peroxymonosulfate to selectively oxidize sulfamethoxazole, a preparation method and application. It is characterized in that the catalyst is polydopamine PDACB co-doped with nitrogen and boron, wherein the atomic proportion of N element is 2.00-5.00%, and the atomic proportion of B element is 25.00-35.00%. Taking advantage of the self-polymerization property of PDA, polydopamine-derived N, B co-doped targeted carbon-based catalysts were prepared using PDA-derived nitrogen-doped carbon material (PDAC) as carbon and nitrogen sources, and boric acid as B source The activation of PMS by PDACB aims to selectively oxidatively degrade the typical pollutant SMX through the non-radical pathway of interfacial electron transfer. The carbon-based material of the present invention is environmentally friendly and economical, can be synthesized on a large scale, has a simple synthesis process and low cost, can strengthen the activation effect on PMS under a wide range of pH conditions, and can realize recycling, and can be applied to activate PMS in antibiotic wastewater Selective oxidation treatment of SMX.

Description

Catalyst for activating persulfate to selectively oxidize sulfamethoxazole and its preparation and application

technical field

The invention relates to a catalyst for efficiently activating permonosulfate (PMS) to selectively oxidize sulfamethoxazole (SMX) and its preparation and application, which belong to the field of antibiotic wastewater treatment technology and the field of new catalytic materials and preparation, and are specifically applied to antibiotics Selective oxidation of SMX by activating PMS in wastewater.

Background technique

Sulfamethoxazole (SMX) is a commonly used sulfonamide antibiotic, mainly used for urinary tract infection, respiratory system infection, intestinal infection, biliary tract infection and local soft tissue or wound infection caused by sensitive bacteria. Although SMX is in a sustained low level (μg·L ^-1 or ng·L ^-1 ) in water, it has significant ecotoxicity. The abuse of drugs by humans and animals leads to excessive residues of SMX in surface water and groundwater, which leads to the generation of drug resistance genes in the human body. Residual SMX has a strong inhibitory effect on microorganisms, and traditional biochemical treatment cannot achieve the expected therapeutic effect. Therefore, it is of great importance to develop efficient and cost-effective treatment technologies to remove residual SMX in aqueous environments.

So far, a large number of water treatment technologies have been developed and applied to remove SMX from water bodies, mainly including adsorption, membrane bioreactor, biochemical and advanced oxidation processes (AOPs). Most of the methods have achieved ideal results in the research of residual SMX treatment in water, but there are certain limitations at the same time. Therefore, in order to completely remove SMX from water, the activated persulfate advanced oxidation method is currently the primary candidate method for most researchers, which has the following advantages: (1) high oxidation potential of sulfate radicals, (2) half-life Long, (3) Wide range of pH applications. Sulfate radicals can be obtained by catalyzing permonosulfate (PMS) through thermal activation, alkali activation, ultrasonic activation, transition metal ion activation, etc. Although the activation method of transition metal ions (such as Co, Mn, Ni and Zn, etc.) is simple to operate and does not consume additional energy, it always inevitably dissolves a large number of metal ions, which brings secondary pollution to the environment and significantly limits the PMS- Wide practical application of AOPs in water treatment. Therefore, it is imperative to design efficient, environmentally friendly, and economical activated PMS catalysts for the typical target antibiotic SMX in water.

Therefore, based on the above-mentioned research status, the basic idea of the present invention is to use the nitrogen-doped carbon material (PDAC) derived from polydopamine (PDA) as a carbon source and nitrogen source, and dope heteroatom B by a simple roasting method to prepare A polydopamine-derived N, B co-doped targeted carbon-based catalyst PDACB. It is applied to the catalytic PMS system, and the non-free radical active species generated in the system is used to selectively oxidize and degrade the typical pollutant SMX. On the one hand, the PMS activation mechanism driven by N, B-co-doped carbon-based materials includes the following aspects: (1) Graphite N with higher electronegativity causes the adjacent carbon to be positively charged through electron transfer, which contributes to PMS is transformed into ¹ O ₂ ; (2) pyrrole N and pyridinium N with a lone pair of electrons form an electron-rich region, which can be used as an active center for electrophilic attack of PMS; (3) B has 3 valence electrons in 2s and 2p orbitals, They can form a ^sp2 hybrid structure similar to carbon materials, so these electrons can effectively break the OO bond of PMS to generate active radicals; (4) There is a good relationship between pyridinic N and B in the graphitized carbon skeleton. The synergistic effect is very beneficial to the generation of non-free radical active species; (5) The carbonyl group (C=O) on the surface of PDACB may play a role in inducing electron transfer from organic pollutants (electron donors) to PMS (electron acceptors) . On the other hand, the general activated PMS oxidation method has a low selectivity of active species, and the composition of the wastewater is complex, with many types of coexisting substrates, high concentrations, and great interference with the removal of target pollutants, often requiring excessive PMS dosing or energy input. Realize the effective removal of trace target pollutants. This not only significantly increases the treatment cost, but also easily produces toxic by-products and increases environmental risks. Therefore, the development of selective activated PMS oxidation technology is of great significance for the innovation of advanced water treatment technology. The key to the development of selective activated PMS oxidation technology is how to design targeted catalysts, find active sites and deeply understand the mechanism of activated PMS. In the present invention, by synergistically adjusting the reactivity of the oxidant PMS and the accessibility of the target pollutant SMX, that is, the interfacial electron transfer pathway, a polydopamine-derived N, B co-doped targeted carbon-based catalyst PDACB is designed to achieve water purification. Selective oxidation of SMX in .

In the research field of efficiently activating PMS to oxidize and remove sulfamethoxazole, Yinghao Li et al. synthesized cobalt ferrite materials with different molar ratios by co-precipitation method to activate PMS to degrade SMX, and the removal rate of SMX under optimal conditions is 91.00%. Yanshan Wang et al. found that the biochar derived from dairy cow dung and biogas residue (DMDB-800) was under the optimal conditions (catalyst dosage 1.0g Lˉ ¹ , PMS dosage 2.5mM, pH 5.56, SMX concentration 15mg When ^Lˉ1 ), the removal rate of SMX within 60min is 90.20%. The red mud sewage sludge-derived biochar (RSDBC) synthesized by Jia Wang et al. can remove 82.50% of SMX within 50 min under optimal conditions. Yan Xu et al. successfully synthesized N, S co-doped biochar (N, S-BC) with a hierarchical porous structure from nanocellulose and thiourea by a one-step pyrolysis method, which can activate the oxidative degradation of PMS within 60 min. 91.32% SMX.

Contents of the invention

The purpose of the present invention is to provide a novel polydopamine-derived N, B co-doped targeted carbon-based catalyst PDACB, another purpose of the present invention is to provide the preparation method of the above catalyst; another purpose of the present invention is to provide Application of the above-mentioned catalyst in the degradation of SMX by activating PMS in antibiotic wastewater.

The technical scheme of the present invention is: activate the catalyst of persulfate (PMS) selective oxidation sulfamethoxazole (SMX), it is characterized in that this catalyst is the polydopamine PDACB of nitrogen (N), boron (B) co-doping , wherein the atomic proportion of N element is 2.00-5.00%, and the atomic proportion of B element is 25.00-35.00%.

The present invention provides a kind of method for preparing above-mentioned catalyst, and its concrete steps are as follows:

(1) N-doping: first, add ammonia water dropwise to the ethanol solution at room temperature and stir, then add dopamine hydrochloride to the mixed solution, and stir at room temperature; add acetone dropwise to the mixed solution, and let stand after the addition is completed Sedimentation treatment; then centrifuge to remove the supernatant, vacuum dry excess acetone and freeze-dry to obtain polydopamine PDA; finally, the material polydopamine PDA is subjected to high-temperature calcination and carbonization treatment in a tube furnace under a protective atmosphere, and the reaction is completed until the tube type After the furnace was cooled to room temperature, the material was washed with deionized water until the pH of the filtrate was 6.50-7.00, and vacuum-dried to obtain the nitrogen-doped carbon material PDAC derived from the material PDA;

(2) B doping: The mixture of nitrogen-doped carbon material PDAC and boric acid is subjected to high-temperature pyrolysis in a tube furnace under a protective atmosphere. After the reaction is completed and the temperature of the tube furnace is cooled to room temperature, the material is washed with deionized water until The pH value of the filtrate was 6.50-7.00, and the material PDACB was obtained by vacuum drying.

The ethanol solution described in the preferred step (1) is that the volume ratio of absolute ethanol and deionized water is 1.00: (4.00-5.00); ammoniacal liquor is the aqueous solution that contains ammonia mass fraction and is 25.00-28.00%; The volume ratio is 1.00:(20.00-25.00); the volume ratio of the mass of dopamine hydrochloride to the ethanol solution is 20-40g· ^Lˉ1 ; the volume ratio of the ethanol solution to acetone is 1.00:(2.00-3.00).

In the preferred step (1), the stirring speed when dripping ammonia water is 200-300rpm, and the stirring time is 20-30min; after adding dopamine hydrochloride, the stirring speed is 250-350rpm, and the stirring time is 20-30h; the time for standing to settle for 24-48h.

Preferably, the freeze-drying temperature in step (1) is -60°C--45°C; the freeze-drying time is 24-48h.

Preferably, the temperature of vacuum drying excess acetone in step (1) is 50-60°C, and the vacuum drying time is 20-40min; the vacuum drying temperature is 80-100°C, and the vacuum drying time is 12-18h; The temperature of vacuum drying described in step (2) is 80-100°C, and the time of vacuum drying is 12-18h.

Preferably, the protective atmosphere described in steps (1) and (2) is nitrogen or argon, the temperature of high-temperature calcination and carbonization treatment is 780-820°C, the heating rate is 4-6°C· ^minˉ1 , and the processing time is 2 -4h; the temperature of the high-temperature pyrolysis described in step (2) is 680-720°C, the heating rate is 4-6°C· ^minˉ1 , and the time of high-temperature pyrolysis is 1-2h.

Preferably, the mass ratio of PDAC and boric acid mixture described in step (2) is 1.00: (3.00-4.00).

The present invention also provides the application of the above-mentioned catalyst in activating PMS to degrade SMX in antibiotic waste water. The specific steps are: add ^PDACB catalyst and PMS to the simulated SMX wastewater whose pH is adjusted to 2.00-12.00 and the concentration is 0.05-0.50mM. 2.00mM, placed in a constant temperature oscillating bed, set the rotation speed at 150-250rpm, and oscillated at 20-60°C for 20-30min.

Beneficial effect:

(1) The carbon-based material of the catalyst of the present invention is environmentally friendly and economically attractive, and can be synthesized on a large scale with a simple synthesis process and low cost;

(2) The catalyst of the present invention uses PDA-derived nitrogen-doped carbon material (PDAC) as a carbon source and nitrogen source, and is doped with heteroatom B by a simple roasting method to prepare polydopamine-derived N, B co-doped The targeted carbon-based catalyst PDACB has a good activation effect on PMS under a wide range of pH conditions, and has a good degradation effect on SMX;

(3) In the process of catalytic activation of PMS of the present invention to selectively oxidize SMX, the non-free radical oxidation mediated by singlet oxygen and interfacial electron transfer realizes strengthening the activation effect on PMS, can accelerate the reaction process, shorten the equilibrium time, and SMX is selective and has no secondary pollution problem;

(4) The catalyst of the present invention can realize recycling and has good economical efficiency.

detailed description

In order to better understand the present invention, the present invention will be further described through the following examples, which are only used to explain the present invention, and will not constitute any limitation to the invention.

Example 1:

(1) Prepare simulated antibiotic wastewater containing SMX, the concentration of SMX is 0.05mM, and the pH value is 8.73.

(2) prepare novel catalyst PDACB, the steps are as follows:

① N-doping step: first, add 4 mL of ammonia water with a mass fraction of 25.00% dropwise to 100 mL of ethanol solution with a volume ratio of absolute ethanol and deionized water of 1.00:4.00 at room temperature and stir at 300 rpm for 20 min, then add to the mixture Add 2.00g of dopamine hydrochloride to the solution, and stir for 24 hours at room temperature at 300rpm; slowly drop 200mL of acetone into the mixed solution under continuous stirring, and let it settle for 24 hours after the addition is complete. Then the supernatant was removed by centrifugation, and the excess acetone was dried under vacuum at 50°C for 40 minutes. After the excess acetone was dried, the sample was freeze-dried in a cold trap at -60°C for 8 hours, and freeze-dried for 48 hours to obtain the material PDA. Finally, the PDA was calcined and carbonized in a tube furnace at 780°C for 2 hours under a nitrogen atmosphere. After the reaction was completed, the tube furnace was cooled to room temperature, and the material was washed with deionized water until the pH of the filtrate was 6.94, and vacuum-dried at 80°C for 18 hours. Get material PDAC;

②B doping step: The mixture of 1.00g PDAC and 3.00g boric acid was pyrolyzed in a tube furnace at 680°C for 1h under a nitrogen atmosphere. The pH value of the filtrate was 6.84, and the material PDACB was obtained by vacuum drying at 80°C for 18 hours, in which the atomic proportion of N element was 2.20%, and the atomic proportion of B element was 26.20%.

Weigh 0.05g of the catalyst PDACB prepared in this example, put it into 100mL of the simulated antibiotic wastewater containing SMX prepared in this example, add 0.14mmol of PMS, place it in a constant temperature shaking bed, 20°C and rotate at 200rpm in 25min Reaching equilibrium, the removal rate of SMX is 98.40%. The catalyst was recycled five times, and the treatment effect could still reach 88.42%.

Example 2:

(1) Prepare simulated antibiotic wastewater containing SMX, the concentration of SMX is 0.50mM, and the pH value is 2.00.

(2) prepare novel catalyst PDACB, the steps are as follows:

① N doping step: first, add 5 mL of ammonia water with a mass fraction of 28.00% dropwise to 100 mL of ethanol solution with a volume ratio of absolute ethanol and deionized water of 1.00:5.00 at room temperature and stir at 200 rpm for 30 min, then add to the mixture Add 4.00g of dopamine hydrochloride into the solution, stir at room temperature 250rpm for 30h; slowly drop 300mL of acetone into the mixed solution under continuous stirring, and let it settle for 48h after the dropwise addition. Then the supernatant was removed by centrifugation, vacuum dried at 60°C for 20 minutes to dry excess acetone, and then the sample was freeze-dried in a cold trap at -45°C for 4 hours, and freeze-dried for 24 hours to obtain the material PDA. Finally, the PDA was calcined and carbonized at a high temperature of 800°C for 4 hours in a tube furnace under an argon atmosphere. After the reaction was completed, the tube furnace was cooled to room temperature, and then the material was washed with deionized water until the pH of the filtrate was 6.91, and vacuum-dried at 100°C. 12h to obtain material PDAC;

②B doping step: pyrolyze the mixture of 1.00g of PDAC and 4.00g of boric acid in a tube furnace at 700°C for 2h in an argon atmosphere, and wash the material with deionized water after the reaction is completed and the tube furnace cools down to room temperature Until the pH value of the filtrate was 6.84, the material PDACB was obtained by vacuum drying at 100°C for 12 hours, in which the atomic proportion of N element was 4.92%, and the atomic proportion of B element was 33.89%.

Weigh 0.10g of the catalyst PDACB prepared in this example, put it into 100mL of the simulated antibiotic wastewater containing SMX prepared in this example, add 0.10mmol of PMS, place it in a constant temperature shaking bed, and set it at 60°C and rotate at 150rpm for 30min When the balance is reached, the removal rate of SMX is 94.38%. The catalyst was recycled 6 times, and the treatment effect could still reach 86.11%.

Example 3:

(1) Prepare simulated antibiotic wastewater containing SMX, the concentration of SMX is 0.10mM, and the pH value is 12.00.

(2) prepare novel catalyst PDACB, the steps are as follows:

① N-doping step: first, add 4 mL of ammonia water with a mass fraction of 26.00% dropwise to 100 mL of ethanol solution with a volume ratio of absolute ethanol and deionized water of 1.00:4.00 at room temperature and stir at 250 rpm for 25 min, then add to the mixture Add 3.00g of dopamine hydrochloride to the solution, and stir for 20h at room temperature at 350rpm; slowly drop 250mL of acetone into the mixture under continuous stirring, and let it settle for 36h after the addition is complete. Then the supernatant was removed by centrifugation, vacuum-dried at 55°C for 30 minutes to dry excess acetone, and then the sample was freeze-dried in a cold trap at -50°C for 6 hours, and freeze-dried for 36 hours to obtain the material PDA. Finally, the PDA was calcined and carbonized at a high temperature of 820°C for 3 hours in a tube furnace under an argon atmosphere. After the reaction was completed, the tube furnace was cooled to room temperature, and then the material was washed with deionized water until the pH of the filtrate was 6.97, and vacuum-dried at 90°C. 15h to obtain material PDAC;

②B doping step: pyrolyze the mixture of 1.00g of PDAC and 3.50g of boric acid in a tube furnace at 720°C for 1h in an argon atmosphere, and wash the material with deionized water after the reaction is completed and the tube furnace cools down to room temperature Until the pH value of the filtrate was 6.92, the material PDACB was obtained by vacuum drying at 90°C for 15 hours, in which the atomic proportion of N element was 3.13%, and the atomic proportion of B element was 31.05%.

Weigh 0.10g of the catalyst PDACB prepared in this example, put it into 100mL of the simulated antibiotic wastewater containing SMX prepared in this example, add 0.20mmol of PMS, place it in a constant temperature shaking bed, at 30°C and rotate at 250rpm in 20min Reaching equilibrium, the removal rate of SMX was 92.11%. The catalyst was recycled five times, and the treatment effect could still reach 86.09%.

Example 4:

(1) Prepare simulated antibiotic wastewater ① containing SMX, and add 40mM Clˉ, NO ₃ ˉ, HCO ₃ ˉ, SO ₄ ² ˉ, PO ₄ ³ ˉ and 50mg·Lˉ1 to ^a part of the prepared simulated wastewater ①. Humic acid, marked as simulated wastewater ②. The concentration of SMX labeled as simulated wastewater was 0.05 mM and the pH value was 8.73.

(2) prepare novel catalyst PDACB, the steps are as follows:

① N-doping step: first, add 4 mL of ammonia water with a mass fraction of 25.00% dropwise to 100 mL of ethanol solution with a volume ratio of absolute ethanol and deionized water of 1.00:4.00 at room temperature and stir at 300 rpm for 20 min, then add to the mixture Add 2.00g of dopamine hydrochloride to the solution, and stir for 24 hours at room temperature at 300rpm; slowly drop 200mL of acetone into the mixed solution under continuous stirring, and let it settle for 24 hours after the addition is complete. Then the supernatant was removed by centrifugation, and the excess acetone was dried under vacuum at 50°C for 40 minutes. After the excess acetone was dried, the sample was freeze-dried in a cold trap at -60°C for 8 hours, and freeze-dried for 48 hours to obtain the material PDA. Finally, the PDA was calcined and carbonized in a tube furnace at 800°C for 2 hours under a nitrogen atmosphere. After the reaction was completed, the tube furnace was cooled to room temperature, and then the material was washed with deionized water until the pH of the filtrate was 6.94, and vacuum-dried at 80°C for 18 hours. Get material PDAC;

②B doping step: pyrolyze the mixture of 1.00g PDAC and 3.00g boric acid in a tube furnace at 700°C for 1h in a nitrogen atmosphere. The pH value of the filtrate was 6.84, and the material PDACB was obtained by vacuum drying at 80°C for 18 hours, in which the atomic proportion of N element was 3.22%, and the atomic proportion of B element was 28.37%.

This example is a comparative example of the SMX removal effect of the catalyst PDACB prepared according to the present invention in the presence of other coexisting substances. Weigh 0.05g of the catalyst PDACB prepared in this example, put it into 100mL of the simulated antibiotic wastewater containing SMX prepared in this example ① and ②, add 0.14mmol of PMS, place it in a constant temperature shaking bed, and rotate at 20°C 200rpm reached equilibrium in 25min, and the removal rates of SMX were 98.40% and 89.77%. The catalyst was reused 5 times, and the treatment effect could still reach 88.42% and 84.64%.

Claims (10)

1. The catalyst for selectively oxidizing sulfamethoxazole by activating peroxymonosulfate is characterized by being nitrogen and boron codoped polydopamine PDACB, wherein the atomic proportion of N element is 2.00-5.00%, and the atomic proportion of B element is 25.00-35.00%.

2. A method for preparing the catalyst of claim 1, comprising the following steps:

(1) N doping: firstly, dropwise adding ammonia water into an ethanol solution and stirring, then adding dopamine hydrochloride into the mixed solution and stirring; dripping acetone into the mixed solution, and standing and settling after the dripping is finished; centrifuging to remove supernatant, vacuum drying excess acetone, and freeze drying to obtain polydopamine PDA; finally, carrying out high-temperature calcination carbonization treatment on the polydopamine PDA under a protective atmosphere, after the reaction is finished and the temperature is reduced, washing the material until the pH value of the filtrate is 6.50-7.00, and carrying out vacuum drying to obtain the nitrogen-doped carbon material PDAC derived from the polydopamine PDA;

(2) B doping: and (3) carrying out high-temperature pyrolysis on the mixture of the nitrogen-doped carbon material PDAC and boric acid in a protective atmosphere, after the reaction is finished and the temperature is reduced, washing the material until the pH value of the filtrate is 6.50-7.00, and carrying out vacuum drying to obtain the material PDACB.

3. The method according to claim 2, wherein the ethanol solution in the step (1) is a mixture of absolute ethanol and deionized water, and the volume ratio of the absolute ethanol to the deionized water is 1.00: (4.00-5.00); the ammonia water is an aqueous solution containing 25.00-28.00% of ammonia by mass fraction; the volume ratio of the ammonia water to the ethanol solution is 1.00: (20.00-25.00); the volume ratio of the mass of the dopamine hydrochloride to the ethanol solution is 20-40 g.L ^ˉ1 (ii) a The volume ratio of the ethanol solution to the acetone is 1.00: (2.00-3.00).

4. The method according to claim 2, wherein the stirring speed in the dropwise addition of the ammonia water in the step (1) is 200 to 300rpm, and the stirring time is 20 to 30min; adding dopamine hydrochloride, and stirring at the speed of 250-350rpm for 20-30h; standing for 24-48h.

5. The method according to claim 2, wherein the temperature of the freeze-drying in the step (1) is-60 ℃ to-45 ℃; the freeze-drying time is 24-48h.

6. The method according to claim 2, wherein the temperature for vacuum drying the excess acetone in the step (1) is 50-60 ℃, and the vacuum drying time is 20-40min; the temperature of the vacuum drying is 80-100 ℃, and the time of the vacuum drying is 12-18h; the temperature of the vacuum drying in the step (2) is 80-100 ℃, and the time of the vacuum drying is 12-18h.

7. The method according to claim 2, wherein the protective atmosphere in steps (1) and (2) is nitrogen or argon, the temperature of the high-temperature calcination carbonization treatment is 780-820 ℃, and the temperature rise rate is 4-6 ℃ min ^ˉ1 The treatment time is 2-4h; the temperature of the high-temperature pyrolysis in the step (2) is 680-720 ℃, and the heating rate is 4-6 ℃ min ^ˉ1 The high-temperature pyrolysis time is 1-2h.

8. The method according to claim 2, wherein the mass ratio of the PDAC to the boric acid mixture in step (2) is 1.00: (3.00-4.00).

9. Use of a catalyst according to claim 1 in activating PMS in degrading SMX in antibiotic wastewater.

10. The application of claim 9, comprising the following specific steps: adding PDACB catalyst and PMS into simulated SMX wastewater with pH adjusted to 2.00-12.00 and concentration of 0.05-0.50mM, wherein the catalyst addition amount is 0.50-1.00 g.L ^ˉ1 The dosage of PMS is 1.00-2.00mM, the PMS is placed in a constant temperature shaking bed, the rotating speed is set to be 150-250rpm, and the shaking reaction is carried out for 20-30min at the temperature of 20-60 ℃.