CN110652982A

CN110652982A - RCW nanosheet modified carbon felt material and preparation method thereof

Info

Publication number: CN110652982A
Application number: CN201810693656.4A
Authority: CN
Inventors: 李轶; 韩晶晶; 李亚楠; 张素鸽
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2018-06-29
Filing date: 2018-06-29
Publication date: 2020-01-07
Anticipated expiration: 2038-06-29
Also published as: CN110652982B

Abstract

The invention discloses an RCW nanosheet modified carbon felt material and a preparation method thereof, and RGO-Ce/WO₃The preparation method of the nanosheet-modified CF material comprises the following steps: uniformly mixing the B1 solution and the B2 solution to obtain a solution B, dissolving graphene oxide in distilled water, and performing ultrasonic treatment for 1-2 hours to form a suspension to obtain a solution A; mixing and stirring solution A and solution B to 10E30min to obtain a precursor solution, and dropwise adding the precursor solution into the precursor solution with the concentration of 2-3 mol.L^‑1Stirring the HCl solution for 10 to 30min, and adding the HCl solution with the concentration of 3 to 5 mmol.L^‑1(NH)₄)₂SO₄Stirring the solution for 10-30 min, soaking CF in the obtained solution for 10-30 min, taking out the CF after soaking, calcining the CF at 180 ℃ for 24h, naturally cooling to room temperature of 20-25 ℃ to obtain RGO-Ce/WO₃A nanosheet-modified CF material; compared with the conventional heterogeneous electro-Fenton technique, the present technique replaces carbon black with RGO and does not use PTFE as a binder, thus preventing an increase in electron transfer resistance and coverage of surface-exposed active sites.

Description

RCW nanosheet modified carbon felt material and preparation method thereof

Technical Field

The invention belongs to the technical field of organic pollution wastewater treatment, and particularly relates to an RCW nanosheet modified carbon felt material and a preparation method thereof.

Background

In recent years, as the harm of residual antibiotics in aquatic ecosystems to the environment and human health is becoming more serious, their removal has attracted a great deal of attention. Especially ciprofloxacin widely used for preventing and treating human and animal diseases, and researches show that the content of ciprofloxacin in waste water reaches 101 g.L^-1. Therefore, it is important to find an effective method for removing CIP (ciprofloxacin) from an aqueous environment.

However, they are difficult to biodegrade and cannot be completely removed by conventional wastewater treatment methods. Therefore, we generally use the electro-Fenton method with an iron species as a catalyst, whose principle is O₂Reduction at the cathode to form H₂O₂；Fe²⁺And H₂O₂Generation of OH and Fe³⁺OH, which is non-selective and strongly oxidizing, reacts with organic substances and finally decomposes them into CO₂、H₂O and inorganic ions; then Fe³⁺Obtain an electron which is changed into Fe²⁺Thus forming a cycle. EF technology can be divided into homogeneous EF and heterogeneous EF, depending on the state of the catalyst iron. In most cases, homogeneous EF technology is adopted, but the reaction conditions of homogeneous EF technology are harsh and must be carried out at pH of about 3, because pH is too high, iron is easily generatedA hydroxide. Whereas heterogeneous EF technology can avoid the above disadvantages and the catalyst can be reused. In heterogeneous EF technology, various iron oxides and iron hydroxides are generally chosen as catalysts, such as Fe₃O₄、α-Fe₂O₃And alpha-FeOOH. But with fenton-like reagents (e.g. Ce)³⁺、Cu⁺And Ni²⁺) Studies for heterogeneous EF technology to degrade CIP are not common. Since the CF cathode is modified by non-ferrous substances and is a combination of homogeneous electro-fenton and heterogeneous electro-fenton, but heterogeneous electro-fenton dominates, we refer to this process as heterogeneous electro-fenton-like. However, in either technique, we can find that finding a suitable cathode material is critical to the success of the experiment, based on the mechanism.

Disclosure of Invention

Aiming at the problems of harsh reaction conditions of homogeneous electro-Fenton technology and difficult biodegradation of quinolone antibiotics CIP, the invention aims to provide an RGO-Ce/WO₃A nanosheet (RCW nanosheet) modified CF material, the RGO-Ce/WO₃The nano-sheet modified CF material takes CF as a matrix and Na₂WO₃·2H₂O as tungsten source, with CeCl₃·7H₂O is cerium source and is obtained through hydrothermal synthesis and normal temperature and pressure drying.

Another object of the present invention is to provide the above RGO-Ce/WO₃The preparation method of the nano-sheet modified CF material is characterized in that under the condition that a binder PTFE is not used, a cathode material of a non-iron catalyst RCW nano-sheet modified CF is synthesized in one step through a hydrothermal method, and CIP is degraded through a heterogeneous electro-Fenton technology.

Another object of the present invention is to provide the above RGO-Ce/WO₃Application of nano-sheet modified CF material in degrading liquid ciprofloxacin by using RGO-Ce/WO₃The nano-sheet modified CF material is used as a cathode, Pt is used as an anode, and the degradation efficiency is 100% under the condition of an external power supply.

The purpose of the invention is realized by the following technical scheme.

RGO-Ce/WO₃The preparation method of the nanosheet-modified CF material comprises the following steps:

1) dissolving tungstate in distilled water, and stirring at the room temperature of 20-25 ℃ for 10-30 min to obtain a B1 solution; adding cerium salt into absolute ethyl alcohol, and stirring at the room temperature of 20-25 ℃ for 10-30 min to obtain a B2 solution; uniformly mixing the B1 solution and the B2 solution to obtain a solution B, wherein the ratio of cerium salt in the B2 solution to tungstate in the B1 solution is (0.01-0.10): 1;

dissolving Graphene Oxide (GO) in distilled water, and performing ultrasonic treatment for 1-2 hours to form a suspension liquid to obtain a solution A;

mixing and stirring the solution A and the solution B for 10-30 min to obtain a precursor solution, wherein Ce and WO in the solution B₃The mass sum of (a) is M1, and the ratio of the mass of the graphene oxide in the solution A to M1 is (0.05-1.0): 1;

in the step 1), the concentration of the tungstate in the B1 solution is 3-12 mmol.L^-1。

In the step 1), the concentration of the cerium salt in the B2 solution is 0.03-0.12 mmol.L^-1。

In the step 1), the ratio of cerium salt in the B2 solution to tungstate in the B1 solution is 0.05: 1.

in the step 1), the ratio of the mass of the graphene oxide in the solution a to the M1 is 1: 3.

2) dropwise adding the precursor solution into the precursor solution under the condition of continuous stirring, wherein the concentration of the precursor solution is 2-3 mol.L^-1Stirring the HCl solution for 10 to 30min, and adding the HCl solution with the concentration of 3 to 5 mmol.L^-1(NH)₄)₂SO₄Stirring the solution for 10-30 min, wherein the mass parts of the precursor solution, the HCl in the HCl solution and (NH) are calculated according to the mass parts₄)₂SO₄In solution (NH)₄)₂SO₄The ratio of the parts by weight of the substances is 80: 3: 0.035;

in the step 2), the unit of the mass part is mg, and the unit of the quantity part of the substance is mmol.

3) Soaking CF in the solution obtained in the step 2) for 10-30 min, taking out the CF after soaking, calcining the CF at 180 ℃ for 24h, naturally cooling to room temperature of 20-25 ℃ to obtain RGO-Ce/WO₃A nanosheet-modified CF material;

wherein, prior to said step 3), the CF is pretreated: soaking CF in H at 60-100 DEG C₂O₂Soaking the mixture in 8-10 wt% HCl solution at 60-100 ℃ for 2-3 h, rinsing the mixture with distilled water, and drying the rinsed mixture at 50-70 ℃.

After said step 3), the RGO-Ce/WO obtained in step 3) is washed with deionized water₃The CF material is modified by the nano-sheets to remove unreacted materials on the CF material, and then the CF material is dried at 50-70 ℃.

In the above technical solution, said H₂O₂H in solution₂O₂The concentration of (A) is 8-10 wt%.

RGO-Ce/WO obtained by the above-mentioned preparation method₃The nanosheet modifies the CF material.

In the above technical scheme, the RGO-Ce/WO₃RGO-Ce/WO on CF in nano-sheet modified CF material₃The loading amount of the nano-sheets is 2.0-7.5 wt%.

The above RGO-Ce/WO₃The nano-sheet modified CF material is applied to degrading CIP as a cathode.

In the above technical scheme, the RGO-Ce/WO₃The degradation efficiency of CIP of the nano-sheet modified CF material is over 90% in 10min, and the degradation efficiency of CIP is 100% in 60 min.

In the above technical scheme, the RGO-Ce/WO₃After the nano-sheet modified CF material is recycled for 5 times in degrading CIP, the CIP degradation efficiency is at least 93%.

The invention has the advantages that:

(1) compared with the traditional heterogeneous electro-Fenton technology, the technology replaces carbon black with RGO and does not use adhesive PTFE, so that the increase of electron transfer resistance and the coverage of surface exposed active sites can be prevented;

(2) in the conventional electro-Fenton system, O₂Is the generation of H by a four-electron reduction process₂O₂The RGO-Ce/WO of the present invention₃The nano-sheet modified CF material is prepared by O₂An electron reduction process of (2) generates more H₂O₂OH, accelerating the formation of oxygen active species;

(3) because of Ce³⁺And H₂O₂OH may also be produced by the reaction, so that CeO₂The addition of (2) prolongs the service life of the electrode;

(4) the CF matrix has strong adsorbability, so that the RCW/CF cathode not only has strong electrocatalytic activity, but also has strong adsorbability, thereby accelerating the degradation of CIP.

Drawings

FIG. 1 is an electrolytic device;

FIG. 2.1 is a graph comparing the effect of three cathodes on CIP oxidative degradation;

FIG. 2.2 is a graph comparing the generation of H for three cathode pairs₂O₂The effect of the amount;

FIG. 2.3 is a graph comparing the effect of three cathodes on TOC;

FIG. 3.1 is a graph showing the effect of different Ce/W molar ratios on the CIP oxidative degradation efficiency in examples 1-5;

FIG. 3.2(a) is the effect of different mass ratios of R/CW on the CIP oxidative degradation efficiency in examples 6-9;

FIG. 3.2(b) is the effect of different mass ratios of R/CW on the efficiency of CIP oxidative degradation in examples 6, 8, 10 and 11;

FIG. 3.3 is a graph showing the effect of RCW loading on CIP oxidative degradation efficiency in examples 3, 12-14;

FIG. 4 is a graph of the effect of applied current on CIP oxidative degradation;

FIG. 5 is Fe²⁺Effect of initial concentration on CIP oxidative degradation;

FIG. 6 is a graph of the effect of electrocatalytic and electro-adsorptive properties of RCW/CF cathodes on CIP oxidative degradation;

FIG. 7 is a graph of the effect of reactive oxygen species on oxidative degradation of CIP investigated with the addition of free radical inhibitors;

FIG. 8 is a survey of the stability of RCW/CF cathodes;

FIG. 9 is a diagram of proposed degradation pathways;

10(a) and (b) are SEM images at different magnifications of pure CF and RCW/CF composite cathode materials, (c) - (e) are TEM images of CW nanosheets and RCW nanosheets, (f) are HR-TEM images of the image-labeled region of (d), and (g) - (k) are Mapping images of the image-labeled region of FIG. 10 (g);

FIG. 11.1(a) is an XPS spectrum of CF;

FIG. 11.1(b) is an XPS spectrum of CW/CF;

FIG. 11.1(c) is an XPS spectrum of RCW/CF;

FIG. 11.2(a) is an XPS spectrum of CW;

FIG. 11.2(b) is an XPS spectrum of RCW;

FIG. 11.2(c) is an XPS spectrum of CW/CF;

FIG. 11.2(d) is an XPS spectrum of RCW/CF;

FIG. 11.3(a) is an XPS spectrum of RCW/CF;

FIG. 11.3(b) is an XPS spectrum of RCW/CF;

FIG. 11.3(c) is an XPS spectrum of CW/CF, RCW/CF and CF;

FIG. 12(a) is N of CW and RCW nanoplates₂Adsorption-removal of attached figures;

figure 12(b) is a plot of the pore size distribution of CW and RCW nanoplates;

FIG. 13.1 is a CV diagram of CW, RCW, CF, CW/CF and RCW/CF;

FIG. 13.2 is an EIS diagram of CW, RCW, CF, CW/CF and RCW/CF.

Detailed Description

Reagents used in the experiment: all chemicals were of analytical grade and no further purification was required.

Ciprofloxacin (C)₁₇H₁₈FN₃O₃Purity is more than or equal to 98%) from Alfa Aesar company in British; na (Na)₂SO₄、FeSO₄·7H₂O、Ce(NO₃)₃·6H₂O and NaWO₃·2H₂O is purchased from Shanghai Aladdin GmbH, and belongs to analytical purity, and the purity is more than or equal to 99.7%;

CF was purchased from capone roland group, france, and methanol and phosphoric acid used as HPLC mobile phases were purchased from sigma aldrich (life science and high tech group, usa).

Graphene Oxide (GO) was synthesized by a modified Hummers method from pure natural graphite (w.s.hummers, r.e.offeman, Preparation of graphite oxide.j.am.chem.soc.80(1958) 1339-.

The apparatus used in the experiment: scanning Electron Microscope (SEM) images and mapping analysis adopt an SU8010 electron emission field coupled X-ray energy chromatograph (EDS) to obtain the morphology and the element composition of the composite cathode material.

Transmission Electron Microscopy (TEM) characterized the morphology and structure of the product.

Nitrogen adsorption-desorption isotherm determination A Quantachrome Autosorb iQ-MP analyzer was used for surface area and pore size analysis at 77K. The total surface area was calculated according to brunauer-emmett-teller calculation (BET) using density functional theory calculation method (DFT) to calculate pore size distribution data based on the adsorption and desorption data.

X-ray photoelectron spectroscopy (XPS) was performed using ESCA X PHI-1600 ray photoelectron spectrometer of PE company, USA, to obtain the binding energy of W4f, Ce 3d, C1 s and O1 s, and 284.6eV is a reference value of the peak of C1 s.

Removal of Total Organic Carbon (TOC) a japanese TOC-VCPH analyzer was used to evaluate the mineralization potential of the treated solution.

In the three-electrode system, the electrochemical activity of the RCW/CF composite electrode material was evaluated by Cyclic Voltammetry (CV) and alternating current impedance spectroscopy (EIS).

The CIP concentration over time was measured using reverse phase high performance liquid chromatography. The CIP degradation intermediates can be followed by high performance liquid chromatography-mass spectrometry (HPLC-MS).

In a specific embodiment of the invention, parts by mass are in mg and parts by mass are in mmol.

In the electrolytic device in the embodiment of the present invention, the size of the cathode material is 6cm × 3cm × 0.5 cm. The anode material was a Pt sheet available from Tianjin England science and technology, Inc. having a size of 1cm × 4cm, as shown in FIG. 1.

An electrolysis device: CIP electro-Fenton degradation was performed in 250mL cylindrical glass cells at room temperature (23. + -. 2 ℃). From 50 mg.L^-1CIP、0.1mmol·L^-1Fe²⁺And 0.05 mol. L^-1Na₂SO₄The solution of the composition simulates CIP wastewater and is treated with NaOH or H₂SO₄The pH of the solution is adjusted. And the solution is continuously 100 mL/min^-1At a rate of introduction of O₂. And the distance between the anode Pt sheet and the RCW/CF composite cathode was 1 cm. And the solution is continuously stirred to ensure the uniformity of the electrolysis process in the electrolysis process. The CIP concentration in each time period is detected by High Performance Liquid Chromatography (HPLC) by taking the degradation efficiency of CIP as an evaluation index. By changing various factors (different proportions of Ce/W and R/CW, RCW load, impressed current and Fe²⁺Initial concentration) to determine the optimal composition and optimal degradation conditions to make early preparation for later industrialization.

The technical scheme of the invention is further explained by combining specific examples.

RGO-Ce/WO of the invention₃The preparation method of the nanosheet-modified CF material (RCW/CF) comprises the following steps:

1) mixing Na₂WO₃·2H₂Dissolving O in distilled water, and stirring for 30min at room temperature of 20-25 ℃ to obtain a B1 solution; reacting CeCl₃·7H₂Adding O into absolute ethyl alcohol, and stirring for 30min at the room temperature of 20-25 ℃ to obtain a B2 solution; uniformly mixing the B1 solution and the B2 solution to obtain a solution B, wherein the CeCl in the B2 solution is calculated according to the amount of the substances₃·7H₂Na in O and B1 solution₂WO₃·2H₂The ratio of O is shown in tables 1 and 2;

dissolving Graphene Oxide (GO) in distilled water, and performing ultrasonic treatment for 2 hours to form a stable suspension liquid to obtain a solution A;

mixing the solution A and the solution B and stirring for 30min to obtain a precursor solution, wherein Ce and WO in the solution B₃Mass sum of M1, mass sum of GO in solution a and ratio of M1 are shown in tables 1 and 2;

in step 1), in B1 solution, Na₂WO₃·2H₂The concentration of O is C1 mmol.L^-1See tables 1 and 2 for details.

In step 1), in B2 solution, CeCl₃·7H₂The concentration of O is C2 mmol.L^-1See tables 1 and 2 for details.

2) Dropwise adding the precursor solution into the precursor solution under the condition of continuous stirring to obtain a precursor solution with a concentration of 3 mol.L^-1Stirring the solution for 30min, and adding HCl solution with the concentration of 5 mmol.L^-1(NH)₄)₂SO₄Stirring the solution for 30min, wherein the mass parts of the precursor solution, the HCl in the HCl solution and (NH) are calculated according to the mass parts₄)₂SO₄In solution (NH)₄)₂SO₄The ratio of the parts by weight of the substances is 80: 3: 0.035;

3) soaking CF in the solution obtained in the step 2) for 30min, taking the CF out after soaking, calcining the CF for 24h at the temperature of 180 ℃, and naturally cooling to the room temperature of 20-25 ℃ to obtain RGO-Ce/WO₃Nanosheet-modified CF Material (in this case, the RGO-Ce/WO-loaded support was weighed₃The CF mass of the nanoplatelets is M3);

wherein, prior to step 3), the CF is pretreated: soaking CF in H at 90 DEG C₂O₂The solution was immersed for 3 hours in a 10% strength by weight HCl solution at 90 ℃ for 1 hour, rinsed with distilled water and dried at 70 ℃ (the weight of CF at this point is M2).

After step 3), the RGO-Ce/WO obtained in step 3) is washed with deionized water₃The nano-sheets modify the CF material to remove unreacted material thereon, and then are dried at 70 ℃.

Examples 1 to 14 were obtained according to the above-mentioned preparation method and the parameters in tables 1 and 2.

TABLE 1 CeCl in B2 solutions of examples 1-11₃·7H₂Na in O and B1 solution₂WO₃·2H₂The ratio of O, the mass of GO in solution a and the ratio of M1, C1 and C2.

TABLE 2 CeCl in B2 solutions in examples 12-15₃·7H₂Na in O and B1 solution₂WO₃·2H₂The ratio of O, the mass of GO and the ratio of M1 in solution a, C1, C2 and loading.

Note: the load calculation formula is as follows: (M3-M2)/M2.

Example 16 comparative example

Ce/WO₃Nanosheet (WO)₃The preparation method of the middle-doped Ce element) modified CF material comprises the following steps:

1) mixing Na₂WO₃·2H₂Dissolving O in distilled water, and stirring for 30min at room temperature of 20-25 ℃ to obtain a B1 solution; reacting CeCl₃·7H₂Adding O into absolute ethyl alcohol, and stirring for 30min at the room temperature of 20-25 ℃ to obtain a B2 solution; uniformly mixing the B1 solution and the B2 solution to obtain a solution B, wherein the CeCl in the B2 solution is calculated according to the amount of the substances₃·7H₂Na in O and B1 solution₂WO₃·2H₂The ratio of O is 0.05: 1;

in step 1), in B1 solution, Na₂WO₃·2H₂The concentration of O was 8.61 mmol. multidot.L^-1。

In step 1), in B2 solution, CeCl₃·7H₂The concentration of O was 0.43 mmol. multidot.L^-1。

2) Dropwise adding 3 mol.L of solution B into the solution B under the condition of continuous stirring^-1Stirring the solution for 30min, and adding HCl solution with the concentration of 5 mmol.L^-1(NH)₄)₂SO₄Stirring the solution for 30min, wherein the mass parts of the solution B, the mass parts of HCl in the HCl solution and the (NH) are calculated according to the mass₄)₂SO₄In solution (NH)₄)₂SO₄The ratio of the parts by weight of the substances is 80: 3: 0.035;

3) soaking CF in the solution obtained in the step 2) for 30min, taking the CF out after soaking, calcining the CF at 180 ℃ for 24h, and naturally cooling to room temperature to obtain Ce/WO₃Nanosheet-modified CF material (CW/CF);

wherein, prior to step 3), the CF is pretreated: soaking CF in H at 90 DEG C₂O₂Soaking in 10 wt% HCl solution at 90 deg.C for 3 hr, rinsing with distilled water, and oven drying at 70 deg.C.

After step 3), the Ce/WO obtained in step 3) is washed with deionized water₃The nano-sheets modify the CF material to remove unreacted material thereon, and then are dried at 70 ℃.

Example 17 comparative example

Ce/WO₃Nanosheet (WO)₃The preparation method of the medium doped Ce element) (CW) comprises the following steps:

3) the solution was transferred to a 100mL stainless steel reactor and calcined at 180 ℃ for 24 h. When the reaction is completed, the autoclave is naturally cooled to room temperature, and then Ce/WO is obtained₃Nanosheets (CW nanosheets).

After step 3, centrifugal filtration and washing of the Ce/WO obtained in step 3) with deionized water₃Nanosheets to remove unreacted material therefrom and then oven-dried at 70 ℃.

Example 18 comparative example

RGO-Ce/WO₃Nanosheet (WO)₃The preparation method of the medium doped Ce element) (RCW) comprises the following steps:

mixing the solution A and the solution B and stirring for 30min to obtain a precursor solution, wherein Ce and WO in the solution B₃The mass sum of (a) is M1, the ratio of the mass of graphene oxide in the solution a to M1 is 1: 3;

2) Dropwise adding the precursor solution into the precursor solution under the condition of continuous stirring to obtain a precursor solution with a concentration of 3 mol.L^-1Stirring the solution for 30min, and adding HCl solution with the concentration of 5mmol·L^-1(NH)₄)₂SO₄Stirring the solution for 30min, wherein the mass parts of the precursor solution, the HCl in the HCl solution and (NH) are calculated according to the mass parts₄)₂SO₄In solution (NH)₄)₂SO₄The ratio of the parts by weight of the substances is 80: 3: 0.035;

3) the solution was transferred to a 100mL stainless steel reactor and calcined at 180 ℃ for 24 h. When the reaction is complete, the autoclave is naturally cooled to room temperature, at which time RGO-Ce/WO is obtained₃Nanoplatelets (RCW nanoplatelets).

After step 3, centrifugal filtration and washing of the RGO-Ce/WO obtained in step 3) with deionized water₃Nanosheets to remove unreacted material therefrom and then oven-dried at 70 ℃.

And (3) performance testing:

1. effect of three cathode materials (CF, CW/CF from example 16 and RCW/CF from example 3) on Ciprofloxacin (CIP) oxidative degradation and H formation₂O₂The effect of the amount and the effect of the TOC.

Reaction conditions are as follows: at room temperature, 50 mg.L of the mixture was prepared^-1CIP、0.1mmol·L^-1Fe²⁺And 0.05 mol. L^-1Na₂SO₄The solution of the composition simulates CIP wastewater and is treated with NaOH or H₂SO₄The pH of the solution was adjusted to 3. Aeration was carried out at 100 mL-min using the RCW/CF obtained in example 3 (loading of RCW on CF was 4.5 wt%), the CW/CF obtained in example 16 (loading of CW on CF was 4.5 wt%), and the purchased Carbon Felt (CF)^-1And reacting for 3 hours under the condition that the applied current is 300mA, measuring the concentration of CIP and calculating the degradation efficiency of the CIP.

The results are shown in FIG. 2: FIG. 2.1 is a graph showing the effect of three cathode materials (CF, CW/CF and RCW/CF) on the oxidative degradation of CIP, and the results show that the RCW/CF cathode material prepared according to the present invention has the highest efficiency of oxidative degradation of CIP, and also show that the synergistic effect of RGO and CW promotes the efficient degradation of CIP.

FIG. 2.2 is a graph of the H generation for the three cathode material pairs (CF, CW/CF and RCW/CF)₂O₂The effect of the amount, the result shows that H is formed₂O₂The amount of (a) is: CF (compact flash)>RCW/CF>CW/CF due to the electrocatalytic properties of RCW and Ce³⁺And H₂O₂The Fenton-like reaction between the two needs to consume a large amount of H₂O₂And addition of RGO improves the electrocatalytic activity of the cathode and produces more H than RCW/CF and CW/CF₂O₂。

Fig. 2.3 is a graph of the effect of three cathode materials on Total Organic Carbon (TOC) showing that the RCW/CF cathode materials have the greatest TOC removal.

2. RGO-Ce/WO of the present invention obtained in examples 1 to 15₃Effect of nanosheet-modified CF material (RCW/CF) on oxidative degradation of CIP.

Reaction conditions are as follows: at room temperature, 50 mg.L of the mixture was prepared^-1CIP、0.1mmol·L^-1Fe²⁺And 0.05 mol. L^-1Na₂SO₄The solution of the composition simulates CIP wastewater and is treated with NaOH or H₂SO₄Adjusting the pH value of the solution to 3 and the aeration rate to 100 mL/min^-1When discussing the influence of the molar ratio of Ce/W and the mass ratio of R/CW on the oxidative degradation of CIP, the loading amount of RCW is controlled to 4.5 wt%, and the ratios of the amounts of substances of Ce/W are set to 0.01, 0.03, 0.05, 0.07 and 0.10, respectively; the ratio of R/CW (mass of GO in solution a and ratio of M1) was 1:1, 1:2, 1:3, 1:4, 1:6 and 2:3, respectively; when discussing the effect of RCW loading on CIP oxidative degradation efficiency, the molar ratio of Ce/W and the mass ratio of R/CW were controlled at 0.05 and 1:3, respectively, and RCW loadings were set at 2.0 wt%, 4.5 wt%, 5.5 wt%, and 7.5 wt%, respectively. The reaction was carried out for 3 hours under the condition that the applied current was 300mA, and the concentration of CIP was measured and the degradation efficiency thereof was calculated.

The results are shown in FIG. 3: FIG. 3.1 is a graph showing the effect of different molar ratios of Ce/W on the efficiency of oxidative degradation of CIP in examples 1-5, and the results show that when the molar ratio of Ce/W is 0.05: 1 (example 3), the best effect on the oxidative degradation of CIP is achieved, the degradation efficiency reaches 94.73% in 10min, and the CIP is completely degraded after being electrified for 1 h.

FIGS. 3.2(a) and (b) are graphs showing the effect of different mass ratios of R/CW (mass of GO in solution A and ratio of M1) on the efficiency of CIP oxidative degradation in examples 6-11, showing that the highest efficiency of CIP degradation is obtained when the mass ratio of R/CW is 1:3 (example 8).

FIG. 3.3 is the effect of RCW loading on CIP oxidative degradation efficiency in examples 3, 12-15, and the results show that the CIP oxidative degradation efficiency is highest when RCW loading is 4.5 wt%.

From the comprehensive graphs of FIGS. 3.1, 3.2 and 3.3, the optimum composition of the RCW/CF cathode material was found to be 0.05 molar ratio of Ce/W, 1:3 mass ratio of R/CW and 4.5 wt% loading of RCW.

3. The effect of impressed current on CIP oxidative degradation was discussed with the optimum composition of RCW/CF (prepared in example 3) as the cathode.

Reaction conditions are as follows: at room temperature, 50 mg.L of the mixture was prepared^-1CIP、0.1mmol·L^-1Fe²⁺And 0.05 mol. L^-1Na₂SO₄The solution of the composition simulates CIP wastewater and is treated with NaOH or H₂SO₄Adjusting the pH value of the solution to 3 and the aeration rate to 100 mL/min^-1When the applied currents were 100mA, 200mA, 300mA, 400mA and 500mA, respectively, the reaction was carried out for 3 hours, and the concentration of CIP was measured and the degradation efficiency thereof was calculated.

The results are shown in FIG. 4: the degradation efficiency of CIP increased with the increase of applied current, and was 84.91%, 94.50%, 94.64% and 94.73% after 10min electrolysis when the applied current was 100mA, 200mA, 300mA and 400mA, respectively. However, when the applied current was further increased to 500mA, the degradation efficiency was reduced to 89.54%. And the graph shows that when the current is 300mA and 400mA, the degradation efficiency is very close and reaches 99.22 percent and 100 percent after 1h respectively. The optimum applied current is 300 mA.

4. Fe was discussed with the optimum composition of RCW/CF (RCW/CF prepared in example 3) as the cathode²⁺Effect of initial concentration on CIP oxidative degradation.

Reaction conditions are as follows: at room temperature, 50 mg.L of the mixture was prepared^-1CIP and 0.05 mol. L^-1Na₂SO₄The solution of the composition simulates CIP wastewater and is treated with NaOH or H₂SO₄Adjusting the pH value of the solution to 3 and the aeration rate to 100 mL/min^-1When being Fe²⁺Initial concentration of each0.05, 0.10, 0.20 and 0.30 mmol.L^-1Then, the reaction was carried out for 3 hours under the condition that the applied current was 300mA, and the concentration of CIP was measured and the degradation efficiency thereof was calculated.

The results are shown in FIG. 5: with Fe²⁺The initial concentration is increased, the degradation efficiency of CIP is increased and then reduced, and the degradation efficiency of CIP after 10min electrolysis is 70.39%, 94.73%, 93.53% and 76.11%, so that the Fe in CIP degradation experiment is²⁺The optimum initial concentration is 0.10 mmol.L^-1。

5. Effect of electrocatalytic and electroadsorptive properties of RCW/CF cathodes of optimal composition (RCW/CF prepared in example 3) on CIP oxidative degradation.

Reaction conditions are as follows: at room temperature, 50 mg.L of the mixture was prepared^-1CIP and 0.05 mol. L^-1Na₂SO₄The solution of the composition simulates CIP wastewater and is treated with NaOH or H₂SO₄Adjusting the pH value of the solution to 3 and the aeration rate to 100 mL/min^-1. In discussing the electrocatalysis of the RCW/CF cathode, the RCW/CF cathode with the optimal composition is used and the CIP wastewater solution is simulated without adding Fe²⁺(ii) a When discussing the electro-adsorption of RCW/CF cathode, pure CF is used as cathode and Fe is not added in the simulated CIP wastewater solution²⁺. The reaction was carried out for 3 hours under the condition that the applied current was 300mA, and the concentration of CIP was measured and the degradation efficiency thereof was calculated.

The results are shown in FIG. 6: the electro-adsorption of the CF caused 48.23% of the CIP to be removed, while the synergy of the electro-catalysis of the RCW and the electro-adsorption of the CF caused 94.73% of the CIP to be removed, indicating that the electro-catalysis of the RCW caused 46.5% of the CIP to be removed. From the figure, it is still clear that CIP removal was complete after 1h in the electro-fenton system, indicating that the strong oxidizing property of OH allows 51.77% CIP removal. In summary, the electro-adsorptivity of CF, the electro-catalysis of RCW, and the in situ electro-generated H₂O₂The synergistic effect of the strong oxidizing property of the reduced OH enables the CIP to be completely degraded within 1 hour.

6. Using the RCW/CF (RCW/CF prepared in example 3) of the optimum composition as a cathode, a radical inhibitor was added to investigate the effect of reactive oxygen species on CIP oxidative degradation.

Reaction conditions are as follows: at room temperature,preparation 50 mg. L^-1CIP and 0.05 mol. L^-1Na₂SO₄The solution of the composition simulates CIP wastewater and is treated with NaOH or H₂SO₄Adjusting the pH value of the solution to 3 and the aeration rate to 100 mL/min^-1Using RCW/CF with optimal composition as cathode, adding different inhibitors (ethanol can inhibit OH and high-valence iron, isopropanol can inhibit OH, and p-benzoquinone can inhibit O)₂ ^-) They were respectively 2.37%, 2.35% and 3.90% by mass, reacted for 3 hours under the condition of an applied current of 300mA, and the concentration of CIP was measured and the degradation efficiency thereof was calculated.

The results are shown in FIG. 7: both ethanol and isopropanol addition significantly reduced CIP degradation efficiency, indicating that OH plays a critical role in CIP oxidative degradation experiments. And it was found that the CIP degradation efficiency is also decreased by the addition of PBQ (p-benzoquinone), a phenomenon which reveals O₂ ^-And the inhibition effect of PBQ on the degradation constant of the electro-Fenton system is about 57 percent, which shows that the RCW composite material causes the reduction of the monomolecular oxygen 1e to generate H₂O₂(O₂→·O₂ ^-→H₂O₂) Is the main cause of CIP degradation.

7. The stability of the RCW/CF cathode (RCW/CF prepared in example 3) of the optimum composition was investigated.

Reaction conditions are as follows: at room temperature, 50 mg.L of the mixture was prepared^-1CIP and 0.05 mol. L^-1Na₂SO₄The solution of the composition simulates CIP wastewater and is treated with NaOH or H₂SO₄Adjusting the pH value of the solution to 3 and the aeration rate to 100 mL/min^-1The reaction was carried out for 3 hours under an applied current of 300mA using RCW/CF (RCW/CF prepared in example 3) of optimum composition as a cathode, and the concentration of CIP was measured and the degradation efficiency was calculated. And this RCW/CF cathode material was recycled 5 times, the concentration of CIP was measured and the degradation efficiency was calculated.

The results are shown in FIG. 8: after the RCW/CF cathode material is recycled for 5 times, the CIP degradation efficiency is reduced by 5.1 percent, but the CIP degradation efficiency is basically kept stable after the fifth cycle, and the CIP removal rate is reduced by about 2 percent. After the fifth cycle, over 93% of the CIP was still degraded, indicating that the cathode material had good stability.

8. A feasible degradation route is proposed.

Reaction conditions are as follows: at room temperature, 50 mg.L of the mixture was prepared^-1CIP and 0.05 mol. L^-1Na₂SO₄The solution of the composition simulates CIP wastewater and is treated with NaOH or H₂SO₄Adjusting the pH value of the solution to 3 and the aeration rate to 100 mL/min^-1After 1 hour of reaction with RCW/CF (RCW/CF prepared in example 3) of the optimum composition as a cathode at an applied current of 300mA, degradation products of CIP were analyzed by HPLC-MS.

The results are shown in FIG. 9: the solution taken out after 1h of degradation is subjected to high performance liquid chromatography-mass spectrometry (HPLC-MS), and through analysis, 7 CIP degradation intermediates are found in the process of the invention, and the invention provides a feasible CIP degradation path according to the intermediates and relevant documents for introducing CIP degradation paths.

9. Investigation of SEM images, mapping images and TEM images of RCW nanoplates of pure CF and RCW/CF (RCW/CF prepared in example 3) composite cathode materials at different magnification.

Reaction conditions are as follows: an SU8010 electron emission field coupled X-ray energy chromatograph (EDS) is adopted for Scanning Electron Microscope (SEM) images and mapping images so as to obtain the morphology of the RCW nanosheet/CF composite electrode material; the Transmission Electron Microscope (TEM) of Tecnai G2F20 model characterizes the morphology and crystal structure of the material.

The results are shown in FIG. 10: 10(a) and 10(b) are SEM images of pure CF and the RCW/CF composite cathode material obtained in example 3 under different times in sequence, and it can be seen that the surface of the CF after acid treatment is rough, which is beneficial to increase the specific surface area of the electrode, so as to promote the reduction of oxygen, and the RCW nano-sheets are randomly loaded on the carbon fibers. Fig. 10(c) -10(e) are TEM images of CW nanosheets (c) obtained in example 17 and RCW nanosheets (D and e) obtained in example 18, from which it can be seen that the CW composite material has a lamellar structure with a diameter of about 8-12nm, but the diameter of the lamellar RCW is larger than that of CW, and the CW nanosheets are found dispersed on the surface of 3D RGO. FIG. 10(f) is a view of FIG. 10(d)HR-TEM image of the labeled region revealed that the RCW nanoplate obtained in example 18 had excellent crystallinity, and WO was found₃There are two lattice spacings, i.e. the lattice spacings of the (020) and (002) lattice planes are d ═ 0.364nm and 0.380nm, respectively, however, HR-TEM images do not reveal any CeO₂Evidence of particles, which may be due to the Ce atoms being much smaller in size than W, also indicates CeO₂High dispersion in WO₃The above. FIGS. 10(h) -10(k) are Mapping plots of the marked areas of the image of FIG. 10(g), showing that the C, O, Ce and W four elements are highly dispersed on the CF.

10. XPS plots of CF, CW/CF obtained in example 16, and RCW/CF obtained in example 3 were investigated.

Reaction conditions are as follows: the binding energy of W4f, Ce 3d, C1 s and O1 s was obtained by ESCA X PHI-1600 ray photoelectron spectrometer of PE company, USA, and 284.6eV was the reference value of the peak of C1 s.

The results are shown in FIG. 11: FIG. 11.1 is a C1 s XPS spectrum of CF, CW/CF obtained in example 16 and RCW/CF material obtained in example 3 showing a sharp peak at a bond energy of 284.7eV, which is associated with a sp²Carbon (C ═ C) related; peaks at bond energies 282.0eV, 285.1eV, and 287.2eV are assigned to sp³Carbon (C-O-C and C-OH) and C ═ O groups; the-OH peak at the bond energy of 286.2eV was only found in the C1 s XPS spectra of the RCW/CF material, which also indicates that the addition of graphene greatly increased the oxidation degree of CF.

FIG. 11.2 is an O1 s XPS spectrum of the CW obtained in example 17, the RCW obtained in example 18, the CW/CF obtained in example 16 and the RCW/CF obtained in example 3, showing that the O1 s spectrum is divided into two parts: the peak with a bond energy of 530.5eV is ascribed to WO₃O in the crystal^2-Lattice oxygen; while the peak having a bond energy of 532.1eV represents O^-Adsorbed oxygen, and the lattice oxygen content of CW (89.08%) and RCW (80.25%) were higher than that of CW/CF (22.58%) and RCW/CF (12.37%), but when CW and RCW were loaded into CF, respectively, the surface adsorbed oxygen content of CW/CF (77.42%) and RCW/CF (87.63%) were much higher than that of CW (10.92%) and RCW (19.75%), all in all cases with the highest adsorbed oxygen content evident in these materials.

FIG. 11.3 is the Ce 3d and W4f spectra of RCW/CF obtained in example 3,and XPS spectra of CF, CW/CF obtained in example 16, and RCW/CF obtained in example 3. FIG. 11.3a is the Ce 3d XPS spectrum of RCW/CF, showing that the XPS spectrum of Ce 3d is divided into two parts: v and u, which represent spin orbitals 3d, respectively_5/2And 3d_3/2Peaks with bond energies of 882.4, 887.7, 898.5, 901.4, 905.8 and 916.9eV (v₀、v₂、v₃、u₀、u₂And u₃) Illustrates Ce⁴⁺And peaks (v) with bond energies of 884.3 and 903.9eV₁And u₁) Then prove Ce³⁺Indicating the presence of Ce in the RCW/CF cathode material⁴⁺And Ce³⁺Ions. FIG. 11.3b is the RCW/CF W4f XPS spectrum, showing that the peaks with 38.2 and 36.0eV bond energies represent the W⁶⁺4f of ion_5/2And 4f_7/2Spin orbit, and peaks with bond energies of 36.1 and 34.6eV correspond to W⁵⁺4f of ion_5/2And 4f_7/2Spin orbit, therefore, the RCW/CF cathode material also contains W⁵⁺And W⁶⁺Two ions. And when CeO₂Loaded to WO₃In favor of W⁶⁺Ion conversion to W⁵⁺Ions. XPS peak analysis of W4f also showed that 13.3% of the W contained in the RCW/CF cathode material was W⁵⁺Is present in the form of (1). Fig. 11.3c is a broad scan spectrum of different cathode materials, from which it can be seen that all the index peaks can be attributed to C, O, W and Ce, which also demonstrates that four elements are present in the cathode material.

11. For CW (Ce/WO prepared in example 17)₃(CW)) and RCW (RCW prepared as in example 18) nanoplates₂Investigation of adsorption-desorption performance.

Reaction conditions are as follows: nitrogen adsorption-desorption isotherm determination a Quantachrome Autosorb iQ-MP analyzer was used for surface area and pore size analysis at 77K; the total surface area is calculated according to brunauer-emmett-teller (BET); and calculating the pore size distribution data by using a density functional theory calculation method (DFT) based on the adsorption and desorption data.

The results are shown in FIG. 12: the mean pore diameter of RCW is twice that of CW, and the specific surface area of RCW is larger than that of CWMuch larger, with a specific area about twice that of CW, which provides a large number of active sites for the reaction, which in turn favors O₂Reduction to H₂O₂Is beneficial to the degradation of CIP.

12. The electrochemical properties of CW, RCW, CF, CW/CF and RCW/CF were investigated.

Reaction conditions are as follows: in the experiment, CHI 660D electrochemical workstation in Shanghai morning and 0.1 mol.L of electrolyte are adopted^-1K₄[Fe(CN)₆]CV and EIS testing of the electrode materials was performed in solution. In the CV test, the scanning speed was set to 0.04 V.s^-1And the scanning is started from a negative potential to a positive potential, the initial potential being-1.0V. In EIS test, the frequency range is 10 Hz-10⁶Hz, applied voltage was 0.8V. The obtained CV and EIS curves were used to analyze the electrochemical properties of the electrode material.

The results are shown in FIG. 13: FIG. 13.1 is a CV plot of CW from example 17, RCW and CF from example 18, CW/CF from example 16, and RCW/CF from example 3, showing that the current densities of the CF, CW/CF, and RCW/CF electrode materials are 10 times that of the CW and RCW, and that the RCW/CF electrode material has the greatest current density.

FIG. 13.2 is an EIS plot of CW, RCW, CF, CW/CF and RCW/CF, showing that the RCW/CF cathode material has minimal electron transfer resistance by combining the advantages of both RCW and CF.

The invention has been described in an illustrative manner, and it is to be understood that any simple variations, modifications or other equivalent changes which can be made by one skilled in the art without departing from the spirit of the invention fall within the scope of the invention.

Claims

1. RGO-Ce/WO₃The preparation method of the nano-sheet modified CF material is characterized by comprising the following steps:

dissolving graphene oxide in distilled water, and performing ultrasonic treatment for 1-2 hours to form a suspension liquid to obtain a solution A;

2. The method according to claim 1, wherein in the step 1), the concentration of the tungstate is 3 to 12 mmol-L in the B1 solution^-1。

3. The method according to claim 2, wherein in the step 1), the concentration of the cerium salt in the B2 solution is 0.03 to 0.12 mmol-L^-1。

4. The method according to claim 3, wherein in the step 1), the ratio of the cerium salt in the B2 solution to the tungstate salt in the B1 solution is 0.05: 1.

5. the preparation method according to claim 4, wherein in the step 1), the ratio of the mass of the graphene oxide in the solution A to the mass of M1 is 1: 3.

6. the method according to any one of claims 1 to 5, wherein in the step 2), the unit of the mass part is mg, and the unit of the amount part of the substance is mmol.

7. The method according to claim 6, wherein the RGO-Ce/WO obtained in step 3) is washed with deionized water after step 3)₃The CF material is modified by the nano-sheets to remove unreacted materials on the CF material, and then the CF material is dried at 50-70 ℃.

8. The method of claim 7, wherein the H is₂O₂H in solution₂O₂The concentration of (A) is 8-10 wt%.

9. RGO-Ce/WO obtained by the preparation method according to any one of claims 1 to 8₃The nanosheet modifies the CF material.

10. The RGO-Ce/WO of claim 9₃A nanosheet-modified CF material, wherein the RGO-Ce/WO₃RGO-Ce/WO on CF in nano-sheet modified CF material₃The loading amount of the nano-sheets is 2.0-7.5 wt%.