Preparation method of catalytic ozone intercalation expanded graphite catalyst, catalyst and application

Abstract

The application provides a preparation method, a catalyst and application of an intercalation expanded graphite catalyst for catalyzing ozone, and belongs to the technical field of graphite materials. First, the expanded graphite is subjected to pre-oxidation treatment to increase the interlayer distance of the expanded graphite, then the pretreated expanded graphite is subjected to intercalation and oxidation through an intercalation substance, and an ion pair compound of triphenylmethyl carbon cation and negatively charged heteropolyanion [P(Mo3O 10 )4] 3‑ is introduced between the layers of the expanded graphite, the compound is stably intercalated between the layers of the graphite, organic pollutants and ozone molecules in waste water are adsorbed, and the effective collision probability and reaction rate between ozone molecules and organic pollutants are improved; finally, the expanded graphite is further treated by using amine substances diethylenetriamine and triethylenetetramine, hydrogen bonds are combined with organic compounds such as phenols, and the adsorption performance of the graphite is improved. The catalyst prepared by the application realizes good removal of tetracycline, phenol and COD in waste water in combination with ozone.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of graphite materials, and particularly relates to a preparation method of a catalytic ozone intercalation expanded graphite catalyst, the catalyst and application. BACKGROUND

[0002] Graphite belongs to hexagonal crystal structure, and the crystal has a sheet structure composed of carbon elements. The carbon atoms on the plane are combined by strong covalent bonds, and the layers are combined by van der Waals force, which is very weak, and the distance between the layers is large. The characteristics of the sheet structure determine a series of properties of graphite. It is proved by X-ray diffraction analysis that other particles such as atoms, ions or atomic groups can be inserted into the interlayer of the crystal graphite by physical or chemical methods, and an intercalation reaction occurs with two electrons in the graphite layer to generate a new layered compound, i.e. graphite intercalation compound (GIC). The interlayer compound can be rapidly decomposed when heated to a proper temperature, and a large amount of gas is generated to expand the graphite into a new material in the form of a worm along the axial direction, i.e. expanded graphite. The unexpanded graphite intercalation compound is expandable graphite.

[0003] The diffraction peak position and peak shape of the expanded graphite are the same as those of pure graphite, indicating that the expanded graphite still maintains the crystal structure of graphite, and has good adsorption effect on polar and non-polar substances. The expanded graphite and natural graphite belong to the hexagonal crystal system, and has the excellent properties of natural graphite such as heat resistance, corrosion resistance, radiation resistance, electrical conductivity and the like, and further has the properties of natural graphite such as resilience, impermeability and adsorption, and has a wide application prospect in the fields of flexible graphite sealing materials, adsorption materials, medical dressings, flame-retardant materials, nanometer conductive fillers, carrier materials, catalysts and military.

[0004] Ozone has strong oxidizing ability, and is widely used in environmental protection and chemical industry. The mechanism of oxidation and degradation of organic pollutants by ozone in water includes direct oxidation and indirect oxidation. The direct oxidation of ozone mainly refers to the strong oxidizing property of ozone itself, which can directly oxidize a part of organic matters in water, usually the reducing organic matters containing unsaturated bonds. The oxidation often has strong selectivity. The indirect oxidation refers to that the ozone molecules dissolved in water can self-decompose in water to generate a large amount of hydroxyl radicals (·OH) with strong oxidizing property, and the oxidation is carried out by the generated hydroxyl radicals as an oxidizing agent. The oxidation can oxidize most of the organic pollutants, and has the "broad-spectrum" of oxidation and degradation. The indirect oxidation of ozone oxidation is considered as the main process of the oxidation process. The ozone oxidation is affected by many factors such as dispersion concentration, temperature, pH, catalyst, adsorbent and the like. In order to further improve the efficiency of the ozone oxidation method, improve the utilization rate of ozone, reduce the operation cost of the ozone oxidation, and further improve the removal efficiency of pollutants, many researchers have developed a high-level oxidation combined process taking ozone as the main body.

[0005] The chemical pharmaceutical wastewater has complex components, large water quantity, great toxicity, contains a large number of heterocyclic and polycyclic substances, and the antibiotic wastewater has antibacterial effect at a very low concentration (100 mg / L), so that the two types of wastewater are extremely difficult to be treated by a biological method.

[0006] The heterocyclic and polycyclic antibiotics are weak polarity, so that the ozone oxidation efficiency is not high, the expanded graphite has adsorption effect on pollutants and ozone, greatly improves the ozone oxidation efficiency, the ozone combination method can achieve better effect than the ozone treatment method alone, but the research on the combination of ozone and expanded graphite for treating organic pollutants in water is little in the prior art. SUMMARY

[0007] In view of the problems in the prior art, the application provides a preparation method, a catalyst and application of a catalytic ozone intercalation expanded graphite catalyst; the preparation process of the catalyst first performs a certain degree of oxidation pretreatment on the graphite by ozone, so that the graphite has a certain degree of hydrophilicity on the basis of maintaining the layered structure of the graphite itself; then, the pretreated expanded graphite is intercalated and oxidized by an intercalation material, so as to introduce macromolecular groups and active groups on the surface of the expanded graphite, further improve the oxidizability of the expanded graphite, and also improve the oxidation rate and efficiency of the ozone, so that the expanded graphite can perform ion exchange or complexation reaction with organic matters in wastewater, effectively remove the organic pollutants in the wastewater, and make the expanded graphite have better chemical adsorption effect.

[0008] The technical effect of the application is realized by the following technical means.

[0009] A preparation method of a catalytic ozone intercalation expanded graphite catalyst, comprising the following steps:

[0010] Step S1: graphite and water are stirred and mixed to obtain a graphite solution, then ozone is introduced into the graphite solution to perform pre-oxidation on the graphite, after the pre-oxidation is completed, the graphite solution is filtered, washed and dried to obtain pretreated graphite;

[0011] Step S2: the acetone solution of phosphomolybdic acid and the pretreated graphite are stirred under heating to obtain solution I, then the acetone solution of trityl chloride is added dropwise into solution I under stirring, after the dropwise addition is completed, the stirring is continued for 2-3 h to obtain solution II; solution II is filtered, washed with water until neutral, and dried to obtain a solid powder;

[0012] Step 3, the solid powder is dissolved in water to obtain a solid powder aqueous solution, diethylene triamine, triethylenetetramine and anhydrous ethanol are mixed to obtain a mixed solution, the mixed solution and the solid powder aqueous solution are mixed under stirring to react, after the reaction is completed, filtration, water washing and finally drying are performed to obtain the intercalated expanded graphite catalyst for catalyzing ozone.

[0013] The graphite in step S1 is flake graphite, and the mesh number of the graphite is 50-120 mesh;

[0014] The mass ratio of the graphite in step S1 to water is 1:2-3;

[0015] The time for introducing ozone in step S1 is 0.5-1 h, and the amount of ozone in the graphite solution is 2-4 mg / L;

[0016] The drying temperature in step S1 is 85-95 ℃, and the drying time is 8-10 h;

[0017] The amount ratio of phosphomolybdic acid to acetone in the phosphomolybdic acid acetone solution in step S2 is 3-8 g:50 ml;

[0018] The mass ratio of the phosphomolybdic acid acetone solution in step S2 to the pretreated graphite is 2-3:1;

[0019] The stirring under heating in step S2 is specifically at a temperature of 65-80 ℃ for 30-40 min;

[0020] The amount ratio of triphenylmethyl chloride to acetone in step S2 is 1.5-3 g:15-20 ml;

[0021] The mass ratio of phosphomolybdic acid to triphenylmethyl chloride in step S2 is 1-3:0.5-3.5;

[0022] The drying temperature in step S2 is 70-85 ℃, and the drying time is 24-36 h;

[0023] The mass ratio of the solid powder to water in step S3 is 1-3:25-40;

[0024] The molar ratio of diethylene triamine to triethylenetetramine in step S3 is 2-5:1-10, and the volume ratio of diethylene triamine to anhydrous ethanol is 2-5:50-55;

[0025] The mass ratio of the solid powder aqueous solution to the mixed solution in step S3 is 2-5:1-2;

[0026] The reaction in step S3 is stirring at room temperature for 24-48 h;

[0027] The drying temperature described in step S3 is 60-80℃.

[0028] An intercalated expanded graphite catalyst for catalyzing ozone production, prepared by the above method.

[0029] The above preparation method describes the application of intercalated expanded graphite catalyst for catalytic ozone in the treatment of pharmaceutical wastewater; the relationship between the amount of ozone used and the amount of pharmaceutical wastewater used is 3 mg / L; the relationship between the amount of intercalated expanded graphite catalyst for catalytic ozone and the amount of pharmaceutical wastewater used is 0.2 g / 100 ml.

[0030] The beneficial effects of this invention are as follows:

[0031] 1. The ozone-catalyzing intercalated expanded graphite catalyst prepared in this invention first pre-oxidizes expanded graphite with ozone, and then obtains slightly oxidized graphite by controlling the ozone introduction rate and time; the slightly oxidized graphite can maintain the layered structure of the graphite itself, i.e., sp... 2 The carbon skeleton is well preserved, the interlayer spacing is slightly increased, and an appropriate amount of oxygen-containing functional groups are introduced, giving graphite a certain degree of hydrophilicity. This provides a good spatial basis for the subsequent insertion of macromolecular intercalation materials into the graphite interlayer. However, excessive pre-oxidation will destroy the carbon skeleton structure of graphite itself, which is not conducive to graphite as a carrier for subsequent intercalation operations.

[0032] 2. Phosphomolybdic acid is a strong acid that can dissociate into a large heteropolyanion [P(Mo3O4)] in polar solvents. 10 )4] 3- Triphenylmethyl chloride readily undergoes heterolytic cleavage in polar solvents, generating a triphenylmethyl carbocation. Due to the conjugation effect of the three benzene rings, its unique spatial structure corresponds to extremely high stability. The positively charged triphenylmethyl carbocation and the negatively charged heteropolyanion [P(Mo3O4]2]2... 10 )4] 3- They combine between graphite layers to form electrically neutral, high-molecular-weight ion-pair compounds. Due to their low polarity and large molecular weight, these compounds have extremely low solubility in organic solvents and water. The triphenylmethyl carbocation and the negatively charged heteropolyanion [P(Mo3O4]2]2... 10 )4] 3- The combination of these compounds, with their large specific surface area and surface acidity, can adsorb organic pollutants and ozone molecules in wastewater, causing them to "accumulate" on the surface of the graphite catalyst. This increases the effective collision probability and reaction rate between ozone molecules and organic pollutants, and in the treatment of phenols and other organic pollutants, it can more thoroughly mineralize organic matter into CO2 and H2O.

[0033] In addition, the benzyl carbocation and the negatively charged heteropoly anion [P(Mo3O] 10 )4]3- The combination of the large organic part of the compound can effectively expand the graphite interlayer, prevent the re-stacking between layers, and form a stable intercalation compound.

[0034] 3. The present application uses amine diethylenetriamine and triethylenetetramine to further treat expanded graphite, introduces amino groups on the surface of expanded graphite which is negative or inert, and the amino groups are protonated under neutral conditions, so that the negative anions can be effectively attracted and captured by electrostatic attraction; the introduced amine groups can be combined with organic compounds such as phenols through hydrogen bonds and dipole-dipole interactions, thereby improving the adsorption performance of the graphite; although the expanded graphite is fluffy, its surface has strong hydrophobicity and is easy to aggregate in water, thereby affecting the utilization of the effective specific surface area, and the hydrophilic amine groups reduce the hydrophobicity of the material, so that the material is more easily dispersed in water and the active sites are fully exposed, thereby making the graphite have better dispersibility, more adsorption sites can contact the pollutants, and the mass transfer process of the pollutants and water molecules is more smooth, thereby improving the overall treatment efficiency.

[0035] 4. The catalytic ozone intercalation expanded graphite catalyst prepared in the present application, in combination with ozone, achieves good removal effects on tetracycline, phenol and COD in wastewater, and provides a practical and feasible technical basis for related technologies. DETAILED DESCRIPTION

[0036] The flake graphite used in the embodiment of the present application has a specification of carbon content > 99%, and a mesh number of 50-120; the phosphomolybdic acid has a content of 99%; and the trityl chloride has a content of 99%.

[0037] The ozone generator involved in the present application is of the OZ-3G type, and the gas source is industrial oxygen; in the pre-oxidation process in the embodiment of the present application, the oxygen flow is set to 5 L / h.

[0038] The preparation process of diethylenetriamine in the embodiment of the present application is as follows:

[0039] In the reaction container, 60.2g of ethylenediamine and 6.1g of ethyleneimine are added, 1.2g of catalyst ferrous sulfate is added, heating to 150 DEG C in an oil bath, and stirring for 2h, and then the obtained reaction liquid is cooled to room temperature to obtain diethylenetriamine, with a yield of 90.8%.

[0040] The preparation process of triethylenetetramine in the embodiment of the present application is as follows:

[0041] In the reaction container, 103g of diethylenetriamine and 10.8g of ethyleneimine are added, 2g of catalyst ferrous sulfate is added, and then heated to 150 DEG C in an oil bath and stirred for 2h, and then the obtained reaction liquid is cooled to room temperature to obtain triethylenetetramine, with a yield of 81.48%.

[0042] In the technical solution of the application, in the application of removing tetracycline, phenol and COD in pharmaceutical wastewater, the relationship between the amount of ozone used and the amount of pharmaceutical wastewater is 3 mg / L; the relationship between the amount of catalytic ozone intercalation expanded graphite catalyst and the amount of pharmaceutical wastewater is 0.2 g / 100 ml.

[0043] Example 1

[0044] Step S1, mix 50g of 50 mesh flake graphite and 100g of deionized water in a container, then place the container on a magnetic stirrer to obtain a graphite solution, then insert the gas production pipe of the ozone generator into the bottom of the container, and introduce ozone into the graphite solution for 0.5h to pre-oxidize the graphite, the amount of ozone in the graphite solution is 2mg / L; after pre-oxidation, the graphite is filtered, then washed with deionized water for 3 times, and dried at 85℃ for 10h to obtain pretreated graphite;

[0045] Step S2, take 3g of phosphomolybdic acid and dissolve it in 50ml of acetone solution, place it on a magnetic stirrer to mix uniformly, then add 21.5g of pretreated graphite, set the heating temperature to 65℃ and stir for 30min to obtain solution I; then take 2g of triphenylmethyl chloride and dissolve it in 20ml of acetone solution, add it dropwise into solution I under stirring conditions, continue to stir for 2h after the dropwise addition is completed, and obtain solution II; filter solution II, wash it with deionized water until solution II is neutral, and dry it at 70℃ for 36h to obtain a solid powder;

[0046] Step 3, dissolve 3g of the solid powder in 40ml of deionized water to obtain a solid powder aqueous solution, mix 2ml (18.6mmol) of diethylenetriamine, 1.4ml (9.3mmol) of triethylenetetramine and 50ml of anhydrous ethanol to obtain a mixed solution, mix the mixed solution and the solid powder aqueous solution under stirring conditions, stir at room temperature for 48h, filter, wash with deionized water after the reaction is completed, and finally dry at 60℃ to obtain a catalytic ozone intercalation expanded graphite catalyst.

[0047] Example 2

[0048] Step S1, mix 50g of 80 mesh flake graphite and 110g of deionized water in a container, then place the container on a magnetic stirrer to obtain a graphite solution, then insert the gas production pipe of the ozone generator into the bottom of the container, and introduce ozone into the graphite solution for 0.5h to pre-oxidize the graphite, the amount of ozone in the graphite solution is 3mg / L; after pre-oxidation, the graphite is filtered, then washed with deionized water for 3 times, and dried at 90℃ for 8h to obtain pretreated graphite;

[0049] Step S2, 5g of phosphomolybdic acid was dissolved in 50ml of acetone solution, placed on a magnetic stirrer to mix evenly, then 16.6g of pretreated graphite was added, set to 80℃ heating and stirring for 30min, to obtain solution I; then 1.5g of triphenylmethyl chloride was dissolved in 20ml of acetone solution, added dropwise to solution I under stirring condition, after dropwise addition, continue to stir for 3h, to obtain solution II, filter solution II, deionized water washing until solution II is neutral, 85℃ drying for 24h, to obtain solid powder;

[0050] Step 3, 2.8g of solid powder was dissolved in 35ml of deionized water to obtain a solid powder aqueous solution, 2ml (18.6mmol) of diethylenetriamine, 2ml (13.4mmol) of triethylenetetramine and 55ml of anhydrous ethanol were mixed to obtain a mixed solution, the mixed solution and the solid powder aqueous solution were mixed under stirring condition, and the reaction was stirred at room temperature for 24h, after the reaction was completed, filtration, deionized water washing, and finally drying at 80℃, to obtain the catalytic ozone intercalation and expansion graphite catalyst.

[0051] Example 3

[0052] Step S1, 50g of flake graphite of 120 mesh and 100g of deionized water were mixed in a container, then the container was placed on a magnetic stirrer to obtain a graphite solution, then the gas production pipe of the ozone generator was inserted into the bottom of the container, and ozone was introduced into the graphite solution for 0.5h to pre-oxidize the graphite, and the amount of ozone in the graphite solution was 4mg / L; after the pre-oxidation was completed, the graphite was filtered, then washed with deionized water for 3 times, and dried at 95℃ for 8h to obtain pretreated graphite;

[0053] Step S2, 3.6g of phosphomolybdic acid was dissolved in 50ml of acetone solution, placed on a magnetic stirrer to mix evenly, then 17.5g of pretreated graphite was added, set to 70℃ heating and stirring for 40min, to obtain solution I; then 2.8g of triphenylmethyl chloride was dissolved in 20ml of acetone solution, added dropwise to solution I under stirring condition, after dropwise addition, continue to stir for 3h, to obtain solution II, filter solution II, deionized water washing until solution II is neutral, 80℃ drying for 36h, to obtain solid powder;

[0054] Step 3, 2.8g of solid powder was dissolved in 35ml of deionized water to obtain a solid powder aqueous solution, 2ml (18.6mmol) of diethylenetriamine, 2ml (13.4mmol) of triethylenetetramine and 55ml of anhydrous ethanol were mixed to obtain a mixed solution, the mixed solution and the solid powder aqueous solution were mixed under stirring condition, and the reaction was stirred at room temperature for 24h, after the reaction was completed, filtration, deionized water washing, and finally drying at 80℃, to obtain the catalytic ozone intercalation and expansion graphite catalyst.

[0055] Comparative Example 1

[0056] Without pretreatment of graphite, solution I was prepared by mixing flake graphite and phosphomolybdic acid in acetone according to step S2 in Example 1, specifically:

[0057] 3g of phosphomolybdic acid was dissolved in 50ml of acetone solution, and then 21.5g of flake graphite was added. The mixture was stirred at 65°C for 30min to obtain solution I. Then 2g of triphenylmethyl chloride was dissolved in 20ml of acetone solution, and the solution was added dropwise to solution I under stirring. After the addition was completed, the solution was stirred for another 2h to obtain solution II. Solution II was filtered, washed with deionized water until it was neutral, and then dried at 70°C for 36h to obtain a solid powder.

[0058] 3g of the solid powder was dissolved in 40ml of deionized water to obtain a solid powder aqueous solution. 2ml (18.6mmol) of diethylenetriamine, 1.4ml (9.3mmol) of triethylenetetramine, and 50ml of anhydrous ethanol were mixed to obtain a mixed solution. The mixed solution and the solid powder aqueous solution were mixed under stirring, and the mixture was stirred at room temperature for 48h. After the reaction was completed, the mixture was filtered, washed with deionized water, and finally dried at 60°C to obtain an intercalated expanded graphite catalyst for catalyzing ozone.

[0059] Comparative Example 2

[0060] According to the preparation process in Example 1, the process of step S2 was not performed, specifically:

[0061] 50g of flake graphite with a particle size of 120 mesh and 100g of deionized water were mixed in a container, and then the container was placed on a magnetic stirrer to obtain a graphite solution. The gas production pipe of an ozone generator was inserted into the bottom of the container, and ozone was introduced into the graphite solution for 0.5h to pre-oxidize the graphite. After the pre-oxidation was completed, the graphite was filtered, washed with deionized water for 3 times, and dried at 95°C for 8h to obtain pretreated graphite.

[0062] 3g of the pretreated graphite was dissolved in 40ml of deionized water to obtain a pretreated graphite aqueous solution. 2ml (18.6mmol) of diethylenetriamine, 1.4ml (9.3mmol) of triethylenetetramine, and 50ml of anhydrous ethanol were mixed to obtain a mixed solution. The mixed solution and the pretreated graphite aqueous solution were mixed under stirring, and the mixture was stirred at room temperature for 48h. After the reaction was completed, the mixture was filtered, washed with deionized water, and finally dried at 60°C to obtain an intercalated expanded graphite catalyst for catalyzing ozone.

[0063] Comparative Example 3

[0064] According to the preparation process in Example 1, the process of step S3 was not performed, specifically:

[0065] Mix 50 mesh 50 g of flake graphite and 100 g of deionized water in a container, then place the container on a magnetic stirrer to stir to obtain a graphite solution, then insert the gas production pipe of the ozone generator into the bottom of the container, and introduce ozone into the graphite solution for 0.5 h to pre-oxidize the graphite. After pre-oxidation, the graphite is filtered, then washed with deionized water 3 times, and dried at 85°C for 10 h to obtain pretreated graphite;

[0066] Step S2, dissolve 3 g of phosphomolybdic acid in 50 ml of acetone solution, place it on a magnetic stirrer to mix uniformly, then add 21.5 g of pretreated graphite, set the heating temperature to 65°C and stir for 30 min to obtain solution I; then dissolve 2 g of triphenylmethyl chloride in 20 ml of acetone solution, add it dropwise to solution I under stirring conditions, continue stirring for 2 h after the addition is complete, filter solution II, wash with deionized water until solution II is neutral, and dry at 70°C for 36 h to obtain the catalytic ozone intercalation and expansion graphite catalyst.

[0067] The conventional treatment process of pharmaceutical wastewater is first pretreated to remove larger suspended solids and floating materials in the wastewater, then the wastewater is adjusted to neutral by acid and alkali, and then the difficult biodegradable colloidal substances and toxic substances are precipitated or floated by adding coagulants (such as polyaluminum chloride) and flocculants (such as polyacrylamide). After that, deep treatment is carried out.

[0068] Application of catalytic ozone intercalation and expansion graphite catalyst:

[0069] The catalytic ozone intercalation and expansion graphite catalysts obtained in Examples 1-3 and Comparative Examples 1-3 are combined with ozone to investigate the removal effect of tetracycline antibiotics and phenol in pharmaceutical wastewater, and the specific application process is as follows:

[0070] (1) Removal of tetracycline in flocculation-treated pharmaceutical wastewater

[0071] Add 100 ml of pharmaceutical wastewater and 0.2 g of catalytic ozone intercalation and expansion graphite catalyst to the container, and at the same time input ozone to the bottom of the container, the concentration of ozone in the wastewater solution is limited to 3 mg / L, and the adsorption is carried out at room temperature and under stirring conditions for 24 h, then detected by high performance liquid chromatography, the removal rate of tetracycline is as high as 99.1%;

[0072] Take two COD pre-prepared reagents, one of which adds 2 ml of distilled water as a blank, and the other of which adds 2 ml of the above static adsorbed pharmaceutical wastewater, then simultaneously digest for 20 min, cool to room temperature, and then detect by water quality detector, the highest content of COD is 3.872 mg / L, which meets the maximum allowable emission concentration of COD 50 mg / L (first level standard) in "Urban Sewage Treatment Plant Pollutant Discharge Standard" (GB 18918-2002).

[0073] (2) Removal of phenol in pharmaceutical wastewater after flocculation treatment

[0074] The content of phenol in pharmaceutical wastewater after flocculation treatment is usually 50-100 mg / L;

[0075] A 100 ml phenol aqueous solution with a concentration of 80 mg / L is prepared, ozone is introduced into the solution, the concentration of ozone in the phenol solution is 3 mg / L, and 0.2 g of the catalytic ozone intercalation expanded graphite catalyst is added into the phenol solution for reaction. After 1 h, the removal rate of phenol is as high as 99.6%. According to the “Integrated Wastewater Discharge Standard” (GB 8978-1996), the maximum allowable discharge concentration of phenol is 0.3 mg / L (first-level standard) or 0.5 mg / L (second-level / third-level standard). By using the catalytic ozone intercalation expanded graphite catalyst prepared by the present application in combination with ozone, the phenolic substances in wastewater can be effectively degraded, which meets the discharge standard.

[0076] Ozone is directly introduced into the above-mentioned pharmaceutical wastewater without adding the catalytic ozone intercalation expanded graphite catalyst, and the removal effects of ozone alone on tetracycline, phenol and COD in the wastewater are investigated. Specifically, 100 ml of the pharmaceutical wastewater after flocculation treatment is taken, and then ozone with a concentration of 3 mg / L is introduced into the wastewater for 1 h. The results show that, when the catalyst prepared by the present application is not added, i.e., when ozone alone is used for oxidation operation of the wastewater, the removal effects of tetracycline, phenol and COD are much lower than those when the catalyst is added.

[0077] The removal results of the catalytic ozone intercalation expanded graphite catalyst obtained in the above-mentioned Examples 1-3 and Comparative Examples 1-3 in combination with ozone on tetracycline, phenol and COD in the pharmaceutical wastewater are shown in Table 1 below:

[0078] Table 1 Removal results of the catalytic ozone intercalation expanded graphite catalyst in combination with ozone on tetracycline, phenol and COD

[0079]

[0080] As can be seen from the above table, the catalyst prepared by the present application in combination with ozone has achieved good technical effects on the removal of tetracycline, phenol and COD in the pharmaceutical wastewater. This is because, after the pre-oxidation of graphite, the interlayer distance of graphite is moderately increased. Comparative Example 1 does not perform pre-oxidation of graphite, which will affect the “enrichment” of the interlayer substance of macromolecules in the graphite interlayer, thereby affecting the adsorption of related substances in the wastewater.

[0081] The intercalation substance belongs to triphenylmethyl carbonium positive ion with positive electricity and heteropoly anion [P(Mo3O 10 )4] 3-The combined macromolecules are insoluble in water and have a huge specific surface area and surface acidity, which can adsorb organic pollutants in wastewater. This also improves the oxidation efficiency and utilization rate of ozone molecules on pollutants, and better treats phenols and other organic pollutants.

[0082] benzyl carbocation and negatively charged heteropoly anion [P(Mo3O4)] 10 )4] 3- The large organic portion of the complex can effectively expand the graphite layers, preventing them from recombinizing and providing a good spatial basis for the subsequent insertion of amines.

[0083] Comparative Example 2 lacked ion-pair compounds containing intercalated triphenylmethyl carbocations and negatively charged heteropoly anions in expanded graphite, which directly affected the activity of expanded graphite in treating organic pollutants and reduced the efficiency of ozone oxidation.

[0084] Introducing hydrophilic amino groups onto the surface of expanded graphite avoids the aggregation problem caused by its strong hydrophobicity, making it easier to disperse in water and fully exposing active sites. This results in better dispersibility of graphite, allowing more adsorption sites to contact pollutants and improving the adsorption performance of graphite.

[0085] Comparative Example 3 did not introduce amino groups on the surface of expanded graphite, which affected the ability of expanded graphite to treat organic pollutants.

[0086] As shown in the table above, the effect of using graphite alone to treat pollutants in wastewater is far less than that of using intercalated expanded graphite catalysts that catalyze ozone. This indicates that the expanded graphite catalyst prepared in this invention, with amino groups on its surface and intercalated ion-pair compound macromolecules, can better catalyze the oxidation of ozone to treat organic pollutants in wastewater.

[0087] The above are merely some preferred embodiments of the present invention and are not intended to limit the scope of the present invention. It should be understood that any modifications, equivalent substitutions, alterations, etc., made in the field of this invention by improving and transforming upon the concept of the present invention should fall within the protection scope of the appended claims.

Claims

1. A method for producing a catalyst for catalyzing intercalation expansion of graphite with ozone, characterized by comprising the steps of: It comprises the following steps: ​ Step S1, graphite and water are stirred and mixed to obtain a graphite solution, then ozone is introduced into the graphite solution to pre-oxidize the graphite, after the pre-oxidation is completed, the graphite solution is filtered, washed and dried to obtain pretreated graphite; Step S2, the acetone solution of phosphomolybdic acid and the pretreated graphite are stirred under heating to obtain solution I, then the acetone solution of triphenylmethyl chloride is added dropwise into solution I under stirring, after the dropwise addition is completed, stirring is continued for 2-3h to obtain solution II; Solution II is filtered, washed with water until neutral, and dried to obtain a solid powder; the mass ratio of the phosphomolybdic acid to the triphenylmethyl chloride is 1-3:0.5-3.5; Step S3, the solid powder is dissolved in water to obtain a solid powder aqueous solution, diethylenetriamine, triethylenetetramine and anhydrous ethanol are mixed to obtain a mixed solution, the mixed solution and the solid powder aqueous solution are mixed under stirring to react, after the reaction is completed, filtration, water washing and finally drying are performed to obtain a catalytic ozone intercalation expanded graphite catalyst.

2. The method for producing a catalytic ozone intercalation graphite catalyst according to claim 1, characterized by, The graphite in step S1 is flake graphite, and the mesh number of the graphite is 50-120 mesh; the mass ratio of the graphite to water is 1:2-3.

3. The method for preparing the intercalated expanded graphite catalyst for catalyzing ozone according to claim 1, characterized in that, The time for introducing ozone in step S1 is 0.5-1h; the amount of ozone in the graphite solution is 2-4mg / L; the drying temperature is 85-95℃, and the drying time is 8-10h.

4. The method for preparing the intercalated expanded graphite catalyst for catalyzing ozone according to claim 1, characterized in that, The amount ratio of phosphomolybdic acid to acetone in the acetone solution of phosphomolybdic acid in step S2 is 3-8g:50ml; the mass ratio of the acetone solution of phosphomolybdic acid to the pretreated graphite is 2-3:1; the stirring under heating specifically is stirring at a temperature of 65-80℃ for 30-40min.

5. The method for preparing the intercalated expanded graphite catalyst for catalyzing ozone according to claim 1, characterized in that, The amount ratio of triphenylmethyl chloride to acetone in step S2 is 1.5-3g:15-20ml; the drying temperature is 70-85℃, and the drying time is 24-36h.

6. The method for preparing the intercalated expanded graphite catalyst for catalyzing ozone according to claim 1, characterized in that, The mass ratio of the solid powder to water in step S3 is 1-3:25-40; the molar ratio of diethylenetriamine to triethylenetetramine is 2-5:1-10; the volume ratio of diethylenetriamine to anhydrous ethanol is 2-5:50-55.

7. The method for preparing the intercalated expanded graphite catalyst for catalyzing ozone according to claim 1, characterized in that, The mass ratio of the solid powder aqueous solution to the mixed solution in step S3 is 2-5:1-2; the reaction is stirring at room temperature for 24-48h; the drying temperature is 60-80℃.

8. A catalytic ozone intercalation expanded graphite catalyst prepared by the preparation method of any one of claims 1-7.

9. The use of the catalytic ozone intercalation expanded graphite catalyst of claim 8 in combination with ozone in the treatment of pharmaceutical wastewater.

10. The use of claim 9, wherein the concentration of ozone in the pharmaceutical wastewater is limited to 3mg / L; and the amount of the catalytic ozone intercalation expanded graphite catalyst used in combination with the pharmaceutical wastewater is 0.2g / 100ml.

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