CN114713260B

CN114713260B - N, S Co-doped Co/CoO/Co 9 S 8 Nano catalyst @ NSOC, preparation method and application thereof

Info

Publication number: CN114713260B
Application number: CN202210357568.3A
Authority: CN
Inventors: 姜维; 刘博�; 周实; 姜宇; 刘春波; 车广波
Original assignee: Jilin Normal University
Current assignee: Jilin Normal University
Priority date: 2022-04-04
Filing date: 2022-04-04
Publication date: 2023-06-16
Anticipated expiration: 2042-04-04
Also published as: CN114713260A

Abstract

The invention discloses Co/CoO/Co Co-doped with Co-MOF derivative N, S ₉ S ₈ An NSOC catalyst, a preparation method and application thereof, belonging to the technical field of metal organic framework derivative materials. The invention aims to solve the defects of high pollution cost, low degradation efficiency and the like of sulfamethoxazole in the existing water treatment, and the invention firstly uses a hydrothermal method to prepare Co-MOF containing N, S element, and then obtains N, S Co-doped catalyst by a calcination mode under a protective atmosphere. The surface of the catalyst prepared by the invention contains rich hydrophilic groups, which is beneficial to the dispersion effect in water; magnetic and can be recovered by magnetic separation; the surface roughness can increase the specific surface area of the catalyst; the catalyst has extremely strong hydrophilicity, and water drops can quickly permeate into the catalyst after contacting the catalyst, thereby being beneficial to improving the catalytic effect. Has very good activation effect on PMS, certain ion interference resistance, and higher recycling property and recycling stability.

Description

N, S Co-doped Co/CoO/Co 9 S 8 Nano catalyst @ NSOC, preparation method and application thereof

Technical Field

The invention belongs to the technical field of metal organic frame derivative materials.

Background

Many areas are now facing serious water pollution, where the problem of contamination with antibiotics is very serious. Antibiotics are chemically stable and poorly biodegradable, toxic, mutagenic and carcinogenic, and thus effective and economical techniques have been developed to deal withThese antibiotics are necessary. Peroxymonosulfate (PMS) catalysis offers the possibility to promote the reaction with small amounts of intermediates under mild conditions and is therefore a very efficient way of antibiotic degradation. The PMS-catalyzed degradation of antibiotics is essentially the generation of sulfate radicals (SO) by catalysts and PMS-catalyzed processes ₄ ^·— ) Hydroxyl radical (. OH), superoxide radical (O) ₂ ^·— ) Singlet oxygen ¹ O ₂ ) Is oxidized and decomposed into inorganic substances such as CO ₂ 、H ₂ O, etc.

In recent years, metal organic framework Materials (MOFs) are widely used as efficient catalysts for CO due to various coordination modes and unique spatial structures ₂ Reduction, hydrogen production, battery and degradation of organic pollutants. However, MOFs are not magnetic, and are difficult to separate from the solution after being directly used as a catalyst for degradation, so that the MOFs are attempted to form metal nano particles with certain magnetism through calcination, and meanwhile, the original framework of the MOFs is maintained, so that the formed carbon-coated metal nano particles are uniformly dispersed in the metal nano particles, the contact area between active sites and pollutants is increased, and the degradation efficiency is improved.

Disclosure of Invention

In order to solve the defects of high pollution cost, low degradation efficiency and the like of Sulfamethoxazole (SMX) in the existing water treatment, the invention aims to provide a preparation method and application of a N, S Co-doped catalyst obtained by calcining Co-MOF containing N, S element in a ligand.

The invention is realized by the following technical scheme:

n, S Co-doped Co/CoO/Co ₉ S ₈ The preparation method of the @ NSOC catalyst specifically comprises the following steps:

the preparation method comprises the following specific steps:

(1) Preparation of Co-MOF containing N, S element:

2.2 to 2.3mmol Co (CH) ₃ COO) ₂ ·4H ₂ O, 2.4 to 2.5mmol of 2, 5-thiophenedicarboxylic acid (H) ₂ tdc), and 2.8 to 2.9mmol of 4,4 '-bipyridine (4, 4' -bpy), dissolved in30mL of water; transferring the obtained mixture into a high-pressure reaction kettle, heating for 5-7 h at 128-132 ℃, and cooling to room temperature to obtain the Co-MOF with pink crystals containing N, S element.

(2) N, S doped Co/CoO/Co ₉ S ₈ Preparation of @ NSOC catalyst:

putting the Co-MOF containing N, S element prepared in the step (1) into a tube furnace, and under a protective atmosphere, keeping the temperature at 4-6 ℃ for min ^-1 Heating to 790-810 deg.C, maintaining for 2.5 hr or more, naturally cooling to room temperature to obtain Co/CoO/Co ₉ S ₈ @ NSOC catalyst.

Preferably, the Co (CH) in step (1) ₃ COO) ₂ ·4H ₂ O:0.54g,2.27mmol, 2, 5-thiophenedicarboxylic acid: 0.42g,2.47mmol, and 4,4' -bipyridine: 0.444g,2.84mmol.

Preferably, the heating temperature in step (1) is 130 ℃.

Preferably, the heating time in step (1) is 6 hours.

Preferably, the rate of temperature increase in step (2) is 5℃min ^-1 。

Preferably, the holding temperature in the tube furnace in step (2) is 800 ℃.

Preferably, the holding time in the tube furnace in step (2) is 3 hours.

Preferably, in step (2) N is maintained in the muffle furnace ₂ And (5) circulating.

Another object of the present invention is to provide a N, S Co-doped Co/CoO/Co ₉ S ₈ The application of the @ NSOC catalyst in the aspect of degrading SMX specifically comprises the following steps:

adding the catalyst and PMS into an SMX aqueous solution, wherein the concentration of the catalyst in the solution is 100mg/L, and the concentration of the PMS is 0.8mM;

preferably, the catalytic degradation temperature is 25 ℃.

The invention has the beneficial effects that:

compared with Co-MOF, the surface of the catalyst prepared by the invention contains rich hydrophilic groups, which is beneficial to the dispersion effect in water; has certain magnetism, and can be recovered by a magnetic separation mode after catalytic degradation is completed; the invention presents a flaky stacked state, has a rough surface and is full of small raised particles, and the structure can increase the specific surface area of the catalyst, thereby being beneficial to contact between pollutants and the catalyst; the catalyst has extremely strong hydrophilicity, and water drops can quickly permeate into the catalyst after contacting the catalyst, thereby being beneficial to improving the catalytic effect.

Tests show that the catalyst has very good activation effect on PMS, has certain ion interference resistance, can adapt to more complex environments, and also has higher recycling property and cycle stability.

Drawings

FIG. 1Co-MOF and Co/CoO/Co ₉ S ₈ XRD spectrum of @ NSOC;

FIG. 2 (a, b) Co/CoO/Co ₉ S ₈ SEM image of @ NSOC; (c) Co/CoO/Co ₉ S ₈ Mapping graph of @ NSOC;

FIG. 3 (a) Co/CoO/Co ₉ S ₈ TEM images of @ NSOC; (b) Co/CoO/Co ₉ S ₈ HRTEM images of @ NSOC;

FIG. 4Co/CoO/Co ₉ S ₈ FT-IR spectrogram of @ NSOC;

FIG. 5Co-MOF and Co/CoO/Co ₉ S ₈ Nitrogen adsorption isotherms for @ NSOC;

FIG. 6Co-MOF and Co/CoO/Co ₉ S ₈ Hysteresis loop of @ NSOC;

FIG. 7Co-MOF and Co/CoO/Co ₉ S ₈ Water contact angle of @ NSOC;

FIG. 8Co/CoO/Co ₉ S ₈ XPS of @ NSOC. Spectra of total spectrum (a), co 2p (b), O1S (C), C1S (d), S2 p (e), N3 d (f);

FIG. 9Co-MOF and Co/CoO/Co ₉ S ₈ Catalytic degradation curve (a) and first order kinetics curve (b) of @ NSOC versus SMX;

FIG. 10 effect of catalyst amount, PMS amount, pH and temperature on catalytic activity;

fig. 11 anti-ion interference experiment: (a) HCO (hydrogen chloride) ₃ ^- ；(b)Cl ^- ；(c)HPO ₄ ^2- The method comprises the steps of carrying out a first treatment on the surface of the (d) Effect of HA on SMX removal

FIG. 12 effect of real body of water on SMX removal;

FIG. 13Co/CoO/Co ₉ S ₈ Cycling experiments of catalytic degradation of SMX by activating PMS with NSOC;

FIG. 14Co/CoO/Co ₉ S ₈ XRD patterns before and after the catalytic degradation of SMX by the NSOC activated PMS;

FIG. 15Co/CoO/Co ₉ S ₈ Active species capture experiments for catalytic degradation of SMX by NSOC activated PMS;

FIG. 16 degradation pathway of SMX.

Detailed Description

The technical scheme of the invention is further explained and illustrated in the following by the form of specific examples.

(1) Preparation of Co-MOF containing N, S element:

co (CH) ₃ COO) ₂ ·4H ₂ O(0.54g，2.27mmol)、H ₂ tdc (0.42 g,2.47 mmol), and 4,4' -bpy (0.444 g,2.84 mmol) were dissolved in 30mL of an aqueous solution. The resulting mixture was transferred to an autoclave and heated to 130℃for 6 hours, cooled to room temperature to give a pink crystal Co-MOF containing N, S elements.

(2) N, S doped Co/CoO/Co ₉ S ₈ Preparing an NSOC catalyst;

putting the Co-MOF containing N, S element prepared in the step (1) into a tube furnace, and adding N into the furnace ₂ Flowing under air at 5 deg.C for min ^-1 Heating to 800 ℃ at the heating rate of (3) h, naturally cooling to room temperature to obtain N, S doped Co/CoO/Co ₉ S ₈ Nano catalyst @ NSOC catalyst

To verify Co/CoO/Co ₉ S ₈ The effect of @ NSOC on activating PMS was studied for its performance in degrading Sulfamethoxazole (SMX). Degradation experiments were performed in a 100mL beaker, which was placed in a thermostatic water bath at a reaction temperature of 25 ℃. 5mg Co/CoO/Co ₉ S ₈ NSOC was homogeneously dispersed in SMX (20 mg L ^-1 50 mL) of the solution, 12.3mg of PMS was added, and after mixing uniformly, l mL of the reaction solution was taken at a certain interval, the obtained sample was filtered through a 0.22 μm filter membrane, andimmediately quenched with 1mL of saturated sodium thiosulfate solution and the SMX content was determined by High Performance Liquid Chromatography (HPLC).

As shown in FIG. 1, successful Co-MOF preparation and Co/CoO/Co were confirmed by XRD ₉ S ₈ Constituent components of @ NSOC. The diffraction peak position accords with Co indicated by a standard card (JCPDS 15-0806), coO indicated by a standard card (JCPDS 43-1004) and Co indicated by a standard card (JCPDS 02-1459) ₉ S ₈ Wherein the diffraction peak at 44.2 ° coincides with the (1 1 1) crystal plane of Co, the diffraction peak at 42.4 ° coincides with the (2 0) crystal plane of CoO, and the diffraction peaks at 31.1 ° and 49.5 ° coincide with Co, respectively ₉ S ₈ The crystal faces (2 2 2) and (3 3 1) are consistent, and the composite material is proved to contain the components.

As shown in FIG. 2, co-MOF is a structure with smooth surface and stacked into blocks from sheets, and Co/CoO/Co obtained after calcination ₉ S ₈ The @ NSOC sheet structure is more obvious, a sheet stacking state is shown, the thickness of the nano sheet is about 300 a nm a, the surface is rough, small raised particles are fully distributed, the specific surface area of the catalyst can be increased, and the contact between pollutants and the catalyst is facilitated.

FIG. 3 shows Co/CoO/Co ₉ S ₈ TEM image of @ NSOC. It can be seen from fig. 3 (a) that the metal in the catalyst exists in the form of nano particles and is coated in a carbon layer, and the carbon layer coating structure can effectively reduce overflow of metal ions. From the HRTEM image, the lattice fringes of the various substances can be clearly seen, wherein lattice fringes with a spacing of 0.30nm and 0.28nm indicate the presence of Co ₉ S ₈ Corresponding to (3 3 1) and (2 2 2) crystal planes, respectively; lattice fringes with a spacing of 0.21nm correspond to the (2 0 0) crystal plane of CoO; the lattice fringes at a spacing of 0.20nm correspond to the (1 1) crystal plane of Co (FIG. 3 (b)), all consistent with XRD results. The above results indicate Co/CoO/Co ₉ S ₈ Successful preparation of the @ NSOC nanocomposite.

Co/CoO/Co as shown in FIG. 4 ₉ S ₈ Fourier infrared spectrum (FT-IR) plot of @ NSOC. Wherein the characteristic peak is located at 620cm ^-1 The nearby absorption peak is generated by sulfonic acid group, 1118cm ^-1 The peak at this point is the tensile vibration peak of s=o, 1630cm ^-1 The nearby absorption peak is generated by-OH in-plane bending vibration ^[15] ，2924cm ^-1 The peak at which corresponds to-CH ₂ Asymmetric stretching vibration peak, which is located at 3000-3600cm ^-1 The broad peak in the range is the tensile vibration peak of O-H. The above results all indicate Co/CoO/Co ₉ S ₈ The @ NSOC contains abundant hydrophilic functional groups, which is beneficial to dispersing in water.

As shown in FIG. 5, co/CoO/Co was studied by nitrogen adsorption experiments ₉ S ₈ Specific surface area and pore size of @ NSOC. The results show that Co/CoO/Co ₉ S ₈ Specific surface area of @ NSOC (209.0267 m ² ·g ^-1 ) Specific Co-MOF (62.8792 m ² ·g ^-1 ) The improvement is 3.3 times. This indicates that Co/CoO/Co obtained by calcination ₉ S ₈ The @ NSOC has a plurality of new pore channels and increased specific surface area.

Co/CoO/Co as in FIG. 6 ₉ S ₈ The aqueous dispersion and magnetic properties of NSOC were tested and the catalyst was added to water to see its uniform dispersion in aqueous solution, which was shown to have typical ferromagnetism by the hysteresis loop. Studies have shown that when the saturation magnetization (Ms) of the magnetic material exceeds 16.3 emu.g ^-1 When the magnetic field is applied, the separation of the magnetic field from the solution can be realized. Tests show that Co/CoO/Co ₉ S ₈ Ms of @ NSOC catalyst was 22.71 emu. G ^-1 . And Ms of the catalyst obtained after one cycle can still reach 17.56 emu.g ^-1 . The result shows that the catalyst has typical weak ferromagnetism, is easy to separate from water body, and is favorable for recycling water.

As shown in FIG. 7, it was further found by contact angle testing that, due to Co/CoO/Co ₉ S ₈ The @ NSOC powder is extremely hydrophilic, and water drops can quickly permeate into the catalyst after contacting the catalyst, so that the hydrophilicity of the catalyst is greatly improved compared with Co-MOF.

As shown in FIG. 8, co/CoO/Co was studied by XPS ₉ S ₈ Surface composition and chemical state of @ NSOC. XPS photoelectron spectroscopy showed the presence of Co, C, N, S and O elements. High resolution at S2 pIn the map, the peak at 168.7eV may be a sulfonic acid group, which is a hydrophilic group effective to enhance the hydrophilicity of the catalyst. The characteristic peaks of N are attributed to pyridine-N, co-N, pyrrole-N and graphite-N. It is believed that all N bond configurations contribute to catalytic activity, except for oxides of nitrogen. In particular, graphite-N has been shown to provide more valence electrons to enhance conductivity and catalytic activity.

As shown in FIG. 9, the effect of the catalyst on activating PMS was investigated when Co/CoO/Co was added simultaneously ₉ S ₈ At the time of @ NSOC and PMS, 98.78% of SMX can be degraded within 10min, and the first-order reaction kinetic constant is as high as 1.31min ^-1 The above results all indicate that the prepared Co/CoO/Co ₉ S ₈ The @ NSOC had very good activation of PMS.

As shown in fig. 10, factors that may affect the degradation rate were explored. With respect to the catalyst and PMS amounts, the reaction rate does not change much as the amount increases to a certain level. For external factors, when the pH of the solution is neutral, the reaction rate is the fastest; the reaction progress is accelerated when the temperature increases.

As shown in fig. 11, since carbonate, chloride ion, phosphate and humic acid are commonly present in the water body, their effect on SMX degradation was studied. The result shows that the catalyst has certain ion interference resistance.

As shown in FIG. 12, the performance of the catalyst for degrading SMX in real water body is studied, when tap water is used as a solvent, although the SMX removal rate can reach about 98% in 10min, the degradation rate is obviously reduced compared with that of a control group, and when the actual river water is used as the solvent, the SMX removal rate is reduced to 87.30% in 10 min. This suggests that some components in real bodies of water may have an inhibitory effect on the degradation of SMX, but this inhibitory effect is not strong.

As shown in FIG. 13, co/CoO/Co ₉ S ₈ After five continuous cyclic degradation SMX experiments, the degradation rate of SMX is not obviously reduced, which indicates Co/CoO/Co ₉ S ₈ The @ NSOC has higher recycling property.

FIG. 14 is Co/CoO/Co ₉ S ₈ Before SMX is circularly degraded by @ NSOCThe XRD pattern is degraded in five times of continuous cycles, co/CoO/Co ₉ S ₈ The composition of @ NSOC did not change significantly, further demonstrating Co/CoO/Co ₉ S ₈ The @ NSOC catalyst has better cycle stability.

As shown in FIG. 15, the results of the radical trapping experiments indicate that Co/CoO/Co is comparable to the quencher-free system ₉ S ₈ The @ NSOC activated PMS degradation SMX reaction was inhibited by the quenchers furfuryl alcohol (FFA), p-Benzoquinone (BQ), methanol (ME) and t-butanol (TBA).

As shown in fig. 16, LC-MS experiments were performed in order to propose a degradation pathway. The degradation route is mainly divided into that methyl on the isoxazole ring is oxidized into carboxyl; the oxidation of isoxazole rings, which breaks due to the attack of active oxygen on the bond between sulphur and nitrogen, is a small molecule compound whose chemical bond is broken through a series of breaks and eventually forms.

Claims

1. N, S Co-doped Co/CoO/Co ₉ S ₈ The preparation method of the @ NSOC catalyst is characterized by comprising the following steps:

(1) Preparation of Co-MOF containing N, S element:

2.2 to 2.3mmol Co (CH) ₃ COO) ₂ ·4H ₂ O, 2.4-2.5 mmol of 2, 5-thiophene dicarboxylic acid, and 2.8-2.9 mmol of 4,4' -bipyridine are dissolved in 30mL of water; transferring the obtained mixture into a high-pressure reaction kettle, heating for 5-7 hours at 128-132 ℃, and cooling to room temperature to obtain pink crystal Co-MOF;

(2) N, S doped Co/CoO/Co ₉ S ₈ Preparation of @ NSOC catalyst:

2. The method according to claim 1, wherein Co (CH ₃ COO) ₂ ·4H ₂ 2.27mmol of O, 2.47mmol of 2, 5-thiophenedicarboxylic acid and 2.84mmol of 4,4' -bipyridine.

3. The process according to claim 1, wherein the heating temperature in step (1) is 130 ℃.

4. The method according to claim 1, wherein the heating time in step (1) is 6 hours.

5. The method according to claim 1, wherein the temperature rise rate in step (2) is 5℃min ^-1 。

6. The process according to claim 1, wherein the holding temperature in the tube furnace in step (2) is 800 ℃.

7. The process according to claim 1, wherein the holding time in the tube furnace in step (2) is 3 hours.

8. N, S Co/CoO/Co Co-doped by the method according to any one of claims 1 to 7 ₉ S ₈ @ NSOC catalyst.

9. A Co/CoO/Co Co-doped according to claim 8 at N, S ₉ S ₈ Use of an NSOC catalyst for degrading SMX.

10. The use according to claim 9, characterized in that it comprises in particular the following steps: the catalyst and the peroxymonosulfate were added to an aqueous solution containing SMX at a catalyst concentration of 100mg/L and a peroxymonosulfate concentration of 0.8mM.