Nanoflower-shaped covalent organic framework material, and preparation method, device and application thereof

Abstract

The application discloses a kind of nanometer flower-like covalent organic framework material and preparation method, device and application, belong to water treatment field.Amino compound and aldehyde compound in the application under the action of catalyst and regulator, formed with specific flower-like structure covalent organic framework structure, continue to react with carboxyl compound, post load metal, obtain the nanometer flower-like covalent organic framework material.Carboxyl in the carboxyl compound in the application has response to uranium in water, and has no response to other metal ions, excludes other interfering ions, in addition, the carboxyl compound also has sulfydryl, can be fixed to subsequent loaded metal ions, improve the loading capacity of metal ions, the nanometer flower-like covalent organic framework material in the application prepared in this way when water treatment, uranium ion can quickly reach adsorption site, and the stability of material as adsorbent is stronger, and adsorption selectivity is also higher.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of water treatment, in particular to a nanoflower-shaped covalent organic framework material, a preparation method, device and application thereof. BACKGROUND

[0002] Seawater contains a large amount of uranium (total reserves of about 4.5 billion tons), which is thousands of times the reserves of land-based uranium mines. Therefore, it is of great significance and environmental value to develop efficient seawater uranium and heavy metal treatment technology. In the prior art, adsorption method has become a research hotspot due to its low cost, simple operation and strong selectivity. The performance of the adsorbent directly determines the treatment efficiency. The developed materials include modified biomass adsorbents, inorganic nanomaterials and metal organic frameworks. These materials form coordination bonds or ion exchange with uranyl ions through surface functional groups to achieve targeted adsorption. Among them, metal organic framework adsorbents have been widely studied due to their excellent adsorption effect.

[0003] Chinese patent application CN118341404A discloses a uranium adsorbent and a preparation method and application thereof. The uranium adsorbent includes a metal organic framework having a nanocage structure; the uranium adsorbent further includes a keggin-type heteropoly acid encapsulated in the nanocage structure in situ; and the metal organic framework is MIL-101(Cr). The uranium adsorbent has high selectivity for uranium, and the uranium adsorption capacity can be as high as 280.60 mg / g or more, and has a long service life.

[0004] CN119056418A discloses a preparation method and application of an iron monatomic porous framework adsorbent for deep purification of uranium-containing wastewater. It relates to a preparation method and application of an adsorbent for deep purification of uranium-containing wastewater. It aims to solve the technical problem of low adsorption capacity of existing metal organic framework uranium adsorbents. The method includes the following steps: preparing ZIF-8 nanocrystals; adjusting the pH of a tannic acid solution to 8 with potassium hydroxide, and then adding it to the ZIF-8 nanocrystal solution to form a stable ZIF-8@K-TA composite; soaking ZIF-8@K-TA in non-hydrated ferric nitrate to obtain ZIF-8@Fe-TA; and drying and calcining under argon gas flow to obtain an iron monatomic porous framework adsorbent. The adsorbent has an adsorption capacity for uranium of 491.46 mg / g and a removal rate of 98.29% in uranium-containing wastewater at pH=6.

[0005] Existing adsorbents are mostly metal organic framework adsorbents, which can only adsorb uranium, and the stability under long-term high salt, high acid and alkali, or high temperature is still not ideal, the response is slow, or the adsorption capacity decays too quickly after multiple uses, and other problems still need to be solved. SUMMARY

[0006] In view of the above problems, the application provides a nano-flower-shaped covalent organic framework material, a preparation method and device thereof and application thereof, the covalent organic framework structure with a flower-shaped structure is prepared through reaction of an amino compound and an aldehyde compound, the covalent organic framework structure is continuously reacted with a carboxyl compound and loaded with metal, and finally the nano-flower-shaped covalent organic framework material for uranium is prepared, which can not only adsorb uranium but also reduce uranium when used for treating wastewater containing uranium, effectively removes uranium in the wastewater, is efficient and has high removal rate, and can be used stably for a long time.

[0007] The application provides a nano-flower-shaped covalent organic framework material, which is prepared from an amino compound and an aldehyde compound through a catalyst and a regulator to obtain a covalent organic framework with a flower-shaped structure, and then through addition of a carboxyl compound and loading of metal ions to obtain a nano-flower-shaped covalent organic framework material loaded with metal.

[0008] The specific surface area (BET value) of the nano-flower-shaped covalent organic framework material is 650-750 m 2 / g, the pore volume is 0.93-0.99 cm 3 / g, and the average pore size is 2.30-2.70 nm; after soaking in an acidic condition, the specific surface area, the pore volume and the pore size are unchanged after soaking in an alkaline condition and after being placed at a high temperature of 200 DEG C.

[0009] Further, in the infrared spectrum of the nano-flower-shaped covalent organic framework material, there are a stretching vibration peak of C-O bond at 1265±0.01 cm -1 , a stretching vibration peak of C=C bond at 1650±0.01 cm -1 , a stretching vibration peak of C-O bond at 1725±0.01 cm -1 , and a stretching vibration peak of -OH bond at 3420±0.01 cm -1 .

[0010] Further, in the X-ray diffraction of the nano-flower-shaped covalent organic framework material, there are (100) and (200) crystal faces corresponding to a covalent organic framework (COF) at 2.79° and 5.58, and a weak (111) crystal face of metal gold at 38.23°.

[0011] The application further provides a preparation method of the nano-flower-shaped covalent organic framework material, which comprises the following steps:

[0012] Step 1, the amino compound and the aldehyde compound are stirred and dispersed in an organic solvent I, a catalyst and a regulator are added, ultrasonic dispersion is carried out, and then the reaction is carried out after being heated, centrifugal separation is carried out on the solid product I after the reaction is completed, the solid product I is washed and dried to obtain a flower-shaped covalent organic framework material.

[0013] Step 2, stirring and dispersing the flower-shaped covalent organic framework material, carboxyl compound and initiator in organic solvent two, placing in a nitrogen atmosphere, continuing to stir after heating to carry out the reaction, centrifuging to separate out the solid product two after the reaction is completed, washing and drying the solid product two to obtain the carboxyl flower-shaped covalent organic framework material;

[0014] Step 3, stirring and dispersing the carboxyl flower-shaped covalent organic framework material in organic solvent three, adding a metal compound, adding a reducing agent after mechanical shaking in the dark, continuing to shake to carry out the reaction in the dark, centrifuging to separate out the solid product three after the reaction is completed, washing and drying the solid product three to obtain the nano flower-shaped covalent organic framework material.

[0015] Further, the molar ratio of the amino compound to the aldehyde compound in step 1 is (2:3)-(3:2).

[0016] Further, the amino compound in step 1 is 1,3,5-tris(4-aminophenyl)benzene.

[0017] Further, the aldehyde compound in step 1 is 2,5-divinyl-1,4-benzene dicarboxaldehyde.

[0018] Further, the reaction process of the 1,3,5-tris(4-aminophenyl)benzene and the 2,5-divinyl-1,4-benzene dicarboxaldehyde is: .

[0019] Further, the stirring and dispersing speed in step 1 is 300-400 rpm, and the stirring and dispersing time is 10-20 min.

[0020] Further, the mass-volume ratio of the amino compound to the organic solvent one in step 1 is (14-15 mg):5 mL.

[0021] Further, the organic solvent one in step 1 is acetonitrile.

[0022] Further, the volume ratio of the catalyst to the organic solvent one in step 1 is (0.2-0.3):5.

[0023] Further, the catalyst in step 1 is one or both of acetic acid and scandium trifluoromethanesulfonate.

[0024] Further, the volume ratio of the regulator to the organic solvent one in step 1 is (0.02-0.025):5.

[0025] Further, the regulator in step 1 is aniline.

[0026] Further, the time of the ultrasonic dispersion in the step 1 is 5-8 min.

[0027] Further, the temperature of the temperature rising in the step 1 is 30-40℃, and the reaction time is 72-75 h.

[0028] Further, the solvent of the washing in the step 1 is tetrahydrofuran and ethanol, and the washing mode is washing for 3-5 times respectively.

[0029] Further, the temperature of the drying in the step 1 is 60-70℃, the vacuum degree of the drying is -0.1 to 0.08 MPa, and the time of the drying is 12-18 h.

[0030] Further, the mass ratio of the flower-like covalent organic framework material, the carboxyl compound and the initiator in the step 2 is (0.12-0.13):(0.13-0.15):(0.01-0.015).

[0031] Further, the carboxyl compound in the step 2 is 2,3-dimercaptosuccinic acid.

[0032] Further, the initiator in the step 2 is azobisisobutyronitrile.

[0033] Further, the speed of the stirring and dispersing in the step 2 is 300-400 rpm, and the time of the stirring and dispersing is 10-20 min.

[0034] Further, the mass-volume ratio of the flower-like covalent organic framework material and the organic solvent two in the step 2 is (0.12-0.13 g):10 mL.

[0035] Further, the organic solvent two in the step 2 is N,N-dimethylformamide.

[0036] Further, the temperature of the temperature rising in the step 2 is 80-90℃.

[0037] Further, the speed of the continuous stirring in the step 2 is 300-400 rpm, and the time of the continuous stirring is 2-2.5 d.

[0038] Further, the solvent of the washing in the step 2 is acetone and ethanol, and the washing mode is washing for 3-5 times respectively.

[0039] Further, the temperature of the drying in the step 2 is 60-70℃, the vacuum degree of the drying is -0.1 to 0.08 MPa, and the time of the drying is 12-15 h.

[0040] Further, the mass-volume ratio of the carboxyl flower-like covalent organic framework material to the organic solvent three in step 3 is (0.1-0.2 g):(50-53 mL).

[0041] Further, the organic solvent three in step 3 is tetrahydrofuran.

[0042] Further, the stirring dispersion speed in step 3 is 300-400 rpm, and the stirring dispersion time is 10-20 min.

[0043] Further, the volume ratio of the metal compound to the organic solvent three in step 3 is (3-4):(50-53).

[0044] Further, the metal in the metal compound in step 3 is one or more of iron, cobalt, nickel, copper, zinc, tin, platinum, palladium, radium, silver, and gold.

[0045] Further, the metal compound is a 0.1wt% tetrachloroauric acid solution.

[0046] Further, the mechanical shaking time in step 3 is 3-4 h.

[0047] Further, the volume ratio of the reducing agent to the organic solvent three in step 3 is (10-15):(50-53).

[0048] Further, the reducing agent in step 3 is a sodium borohydride solution with a concentration of 13.3 mg / L, and the solvent is tetrahydrofuran.

[0049] Further, the frequency of the mechanical shaking and continuous shaking in step 3 is 50-60 times / min.

[0050] Further, the reaction time in step 3 is 3-4 h.

[0051] Further, the washing solvent in step 3 is acetone and ethanol, and the washing method is washing 3-5 times respectively.

[0052] Further, the drying temperature in step 3 is 60-80℃, the vacuum degree of the drying is -0.1 to 0.08 MPa, and the drying time is 8-12 h.

[0053] The application also provides a water treatment device comprising the nano flower-like covalent organic framework material, which comprises a filtration assembly and an ultrafiltration assembly, the filtration assembly comprises a first filter and a second filter, and the ultrafiltration assembly comprises an ultrafiltration membrane and the nano flower-like covalent organic framework material.

[0054] The first filter, the second filter and the ultrafiltration assembly are all of an up-in and down-out structure;

[0055] The first filter, the second filter and the ultrafiltration assembly are connected through pipes;

[0056] A first filter membrane is arranged in the first filter, and the pore size of the first filter membrane is 400-500 nm;

[0057] A second filter membrane is arranged in the second filter, and the pore size of the second filter membrane is 200-300 nm;

[0058] The pore size of the ultrafiltration membrane is 2-5 nm;

[0059] The first filter membrane and the second filter membrane are both located at the bottom of the first filter and the second filter, and the ultrafiltration membrane is located at a 1 / 4-3 / 4 position of the ultrafiltration assembly; the nano-flower-shaped covalent organic framework material is filled below the ultrafiltration membrane, and the filling capacity of the nano-flower-shaped covalent organic framework material is 1 / 4-3 / 4 of the ultrafiltration assembly;

[0060] The first filter membrane, the second filter membrane and the ultrafiltration membrane are fixed in the first filter, the second filter and the ultrafiltration assembly by a threaded and screwed sealing mode.

[0061] Further, the preparation method of the ultrafiltration membrane, the ultrafiltration membrane is a polysulfone-polyethylene glycol membrane, and the preparation method of the polysulfone-polyethylene glycol membrane comprises the following steps:

[0062] S1. Under a nitrogen atmosphere, bisphenol A, 4,4'-dichlorodiphenyl sulfone and potassium carbonate are stirred and dissolved in dimethylacetamide and toluene, and then heated to toluene reflux. Water in the system is removed during the reflux process. Continue to heat for polymerization reaction. Add methoxypolyethylene glycol for continuous reaction. After reaction, cool to room temperature to stop polymerization. Pour the reaction into a precipitator. After filtration, wash the solid product. Continue to dry the washed product to constant weight to obtain a polymerization precursor;

[0063] S2. The polymerization precursor is dispersed in an organic solvent, heated and stirred, and then degassed at room temperature to obtain a polymerization liquid;

[0064] S3. The polymerization liquid is cast onto a clean glass plate, and then immediately immersed in deionized water. After taking out the cooled solid-state membrane, it is placed in new deionized water to remove residual solvents. Then the solid-state membrane is placed in deionized water for annealing to obtain the polysulfone-polyethylene glycol membrane.

[0065] Further, the molar ratio of the bisphenol A and the 4,4'-dichlorodiphenyl sulfone in the S1 is (1:2)-(2:1).

[0066] Further, the molar ratio of the potassium carbonate and the bisphenol A in the S1 is (3:1)-(6:1).

[0067] Further, the speed of the stirring in the S1 is 300-500 rpm, and the time of the stirring is 10-20 min.

[0068] Further, the mass-volume ratio of the bisphenol A, the dimethylacetamide and the toluene in the S1 is (45-48 g):(450-500 mL):(100-200 mL).

[0069] Further, the temperature of the heating in the S1 is 150-170℃.

[0070] Further, the temperature of the continued heating in the S1 is 180-200℃.

[0071] Further, the time of the polymerization reaction in the S1 is 5-6 h.

[0072] Further, the mass ratio of the methoxy polyethylene glycol and the bisphenol A in the S1 is (50-52):(45-48).

[0073] Further, the time of the continued reaction in the S1 is 2-3 h.

[0074] Further, the volume ratio of the precipitant and the dimethylacetamide in the S1 is (4-5):1.

[0075] Further, the precipitant in the S1 is 0.4-0.6 mol / L HCl aqueous solution.

[0076] Further, the solvent for the washing in the S1 is deionized water, and the washing liquid is neutral.

[0077] Further, the temperature of the drying in the S1 is 60-80℃, and the vacuum degree of the drying is -0.01 to 0.08 MPa.

[0078] Further, the mass ratio of the polymerization precursor and the organic solvent in the S2 is (10-15):(85-90).

[0079] Further, the organic solvent in the S2 is N-methyl-2-pyrrolidone (NMP).

[0080] Further, the temperature of the heating in the S2 is 30-50℃.

[0081] Further, the stirring speed in S2 is 300-350 rpm, and the stirring time is 12-15 h.

[0082] Further, the time for room temperature degassing in S2 is 12-15 h.

[0083] Further, the film thickness of the casting in S3 is 200-300 µm.

[0084] Further, the temperature of the deionized water in S3 is 40-45℃, and the immersion time is 10-20 min.

[0085] Further, the time for placing in new deionized water in S3 is 2-3 h.

[0086] Further, the annealing temperature in S3 is 80-100℃, and the annealing time is 8-24 h.

[0087] The application further provides an application of the water treatment device, which is used for treating uranium-containing wastewater, and the BOD5 content of the treated water is 3-4 mg / L, the total suspended solids content is 3-4 mg / L, the dissolved oxygen content is 4-5 mg / L, the total coliform group number is 112-115, and the uranium content is 15-30 µg / L.

[0088] The adsorption-reduction rate of the nanoflower-shaped covalent organic framework material to uranium in the water treatment device is 96.5-97.5%.

[0089] Further, the treatment method of the water treatment device comprises the following steps:

[0090] The uranium-containing wastewater is sequentially introduced into the first filter and the second filter at 5 mL / min, and the particles such as suspended matters of >450 nm and >220 nm are sequentially filtered out, then the wastewater is continuously introduced into the ultrafiltration assembly, and after ultrafiltration by the ultrafiltration membrane, the wastewater is adsorbed and reduced by the nanoflower-shaped covalent organic framework material, and the treated uranium-containing wastewater flows out from the water outlet below the ultrafiltration assembly.

[0091] The application has the following beneficial effects:

[0092] The 1,3,5-tris (4-aminophenyl) benzene and 2,5-divinyl-1,4-benzene are formed into the covalent organic framework structure with specific flower-like structure under the action of the catalyst and the regulator, compared with the metal organic framework, the covalent organic framework in the application has high covalent bond energy and strong structure rigidity, is not easy to decompose in the complex environment such as high salt of seawater, acid-base fluctuation, and the like, and the carboxyl group responding to the metal uranium is continuously added to the covalent organic framework, meanwhile, the compound with the carboxyl used in the application contains the mercapto group, and the metal ion can be stably fixed in the subsequent metal loading process, the metal ion is converted into the 0-valence or low-valence metal under the action of the reducing agent, and is thus loaded on the nanometer flower-like covalent organic framework material, the nanometer flower-like covalent organic framework material prepared by the application can quickly reach the adsorption site, the material has stronger stability and higher adsorption selectivity as the adsorbent, and the uranium is reduced at the same time of adsorption, and the treatment efficiency of the uranium and the service life of the material are improved.

[0093] The material in the application can also be used to prepare a water treatment device, after the sewage is preliminarily filtered, the total suspended solids and the dissolved oxygen and other difficult-to-remove soluble impurities are removed through ultrafiltration, and then the nanometer flower-like covalent organic framework material in the application is used for adsorption and reduction, the uranium in the water exists in the form of uranyl ion (UO2 2+ ), is anchored and adsorbed through the carboxyl in the nanometer flower-like covalent organic framework material, and is reduced into the tetravalent uranium (UO2 2+ ) under the action of the reducing agent, the loaded metal gold has good conductivity, and can accelerate the process of electron transfer in the reduction process, so that the adsorption-reduction process of the uranium is quickly completed under the action of the nanometer flower-like covalent organic framework material in the application, the reduced uranium dioxide is deposited at the bottom of the device, the water treatment device in the application has the advantages of fast treatment speed, low uranium content and high treatment efficiency for the uranium-containing sewage, and the metal loading process in the application can use various metal ions for loading, different metals can be selected for loading under different fields and different adsorption standards, and the application is suitable for various industries and standards. BRIEF DESCRIPTION OF DRAWINGS

[0094] Figure 1 It is a transmission electron microscope image of the flower-like covalent organic framework material described in the embodiment 1.

[0095] Figure 2 It is a transmission electron microscope image of the flower-like covalent organic framework material (single) described in the embodiment 1.

[0096] Figure 3 It is a transmission electron microscope image of the nanometer flower-like covalent organic framework material (single) described in the embodiment 1.

[0097] Figure 4A structural schematic diagram of the nanoflower-shaped covalent organic framework material described in this embodiment 1;

[0098] Figure 5 A structural schematic diagram of the synthesis of the nanoflower-shaped covalent organic framework material described in this embodiment 1;

[0099] Figure 6 X-ray diffraction patterns of the nanoflower-shaped covalent organic framework material and the carboxyl flower-shaped covalent organic framework material described in this embodiment 1;

[0100] Figure 7 Partial X-ray diffraction patterns of the nanoflower-shaped covalent organic framework material and the carboxyl flower-shaped covalent organic framework material described in this embodiment 1;

[0101] Figure 8 Infrared spectrograms of the nanoflower-shaped covalent organic framework material and the carboxyl flower-shaped covalent organic framework material described in this embodiment 1;

[0102] Figure 9 A reduction reaction kinetics diagram of the nanoflower-shaped covalent organic framework material described in this embodiment 1;

[0103] Figure 10 A specific surface area diagram of each stage of the material described in this embodiment 1;

[0104] Figure 11 A structural schematic diagram of the water treatment device described in the present application, in which each number and name is: 1, a filtration assembly; 2, an ultrafiltration assembly; 11, a first filter; 12, a second filter; 101, a first filtration membrane; 102, a second filtration membrane; 201, an ultrafiltration membrane; 202, a nanoflower-shaped covalent organic framework material;

[0105] Figure 12 A scanning electron microscope diagram of the nanometer covalent organic framework material described in this comparative example 1;

[0106] Figure 13 A scanning electron microscope diagram of the nanometer covalent organic framework material described in this comparative example 4. DETAILED DESCRIPTION

[0107] The application is described in detail below in combination with embodiments:

[0108] The present application provides a nanoflower-shaped covalent organic framework material and a preparation method, device and application, which is prepared by reacting an amino compound and an aldehyde compound to obtain a covalent organic framework structure with a flower-shaped structure, and then adding a carboxyl compound and loading a metal to finally prepare a nanoflower-shaped covalent organic framework material for uranium, which can effectively remove uranium in water when used for treating wastewater, is efficient and has a high removal rate.

[0109] Embodiment 1

[0110] The embodiment provides a nanoflower-shaped covalent organic framework material, wherein the nanoflower-shaped covalent organic framework material is prepared by using an amino compound and an aldehyde-based compound, and is catalyzed by a catalyst and regulated by a regulator to obtain a covalent organic framework with a flower-shaped structure, and then is added with a carboxyl compound and loaded with metal ions to obtain the nanoflower-shaped covalent organic framework material loaded with metal ions.

[0111] The nanoflower-shaped covalent organic framework material has a specific surface area (BET value) of 671 m 2 / g, a pore volume of 0.93 cm 3 / g, and an average pore size of 2.57 nm; after being soaked in an acidic condition, the specific surface area, the pore volume and the pore size are unchanged after being soaked in an alkaline condition and after being placed at a high temperature of 200 DEG C.

[0112] The embodiment further provides a preparation method of the nanoflower-shaped covalent organic framework material, and the method comprises the following steps:

[0113] Step 1, 14.16 mg (0.04 mmol) of 1,3,5-tris (4-aminophenyl) benzene and 11.12 mg (0.06 mmol) of 2,5-divinyl-1,4-benzene dialdehyde are dispersed in 5 mL of acetonitrile under stirring at 300 rpm for 10 min, 0.3 mL of acetic acid and 0.024 mL of aniline are added, ultrasonic treatment is performed for 5 min, then the temperature is increased to 30 DEG C, and reaction is performed for 72 h; after the reaction is completed, a solid product I is separated by centrifugation, the solid product I is washed with tetrahydrofuran and ethanol for three times respectively, and then is dried at 60 DEG C under-0.1 MPa for 12 h, so as to obtain a flower-shaped covalent organic framework material;

[0114] Step 2, 0.12 g of the flower-shaped covalent organic framework material, 0.14 g of 2,3-dimercaptosuccinic acid and 0.015 g of azobisisobutyronitrile are dispersed in 10 mL of N,N-dimethylformamide under stirring at 300 rpm for 10 min, then are placed in a nitrogen atmosphere, the temperature is increased to 80 DEG C, and reaction is continuously performed under stirring at 300 rpm for 2 d; after the reaction is completed, a solid product II is separated by centrifugation, the solid product II is washed with acetone and ethanol for three times respectively, and then is dried at 60 DEG C under-0.1 MPa for 12 h, so as to obtain a carboxyl flower-shaped covalent organic framework material;

[0115] Step 3, 0.1 g of the carboxyl flower-shaped covalent organic framework material is dispersed in 52.5 mL of tetrahydrofuran under stirring at 300 rpm for 10 min, 3.75 mL of 0.1 wt% tetrachloroauric acid solution is added, after mechanical shaking for 3 h in the dark, 15 mL of 13.3 mg / L sodium borohydride solution (solvent is tetrahydrofuran) is added, and the shaking reaction is continued in the dark for 3 h, the frequency of shaking is 60 times / min, after washing with acetone and ethanol for 3 times respectively, drying at 60°C under-0.1 MPa for 12 h, the nano flower-shaped covalent organic framework material is obtained.

[0116] The embodiment also provides a water treatment device comprising the nano flower-shaped covalent organic framework material, the water treatment device comprises a filtration assembly 1 and an ultrafiltration assembly 2, the filtration assembly 1 comprises a first filter 11 and a second filter 12, the ultrafiltration assembly 2 comprises an ultrafiltration membrane 201 and the nano flower-shaped covalent organic framework material 202;

[0117] The first filter 11, the second filter 12 and the ultrafiltration assembly 2 are all in an up-in and down-out structure;

[0118] The first filter 11, the second filter 12 and the ultrafiltration assembly 2 are connected through pipelines;

[0119] A first filtration membrane 101 is arranged in the first filter 11, and the pore size of the first filtration membrane 101 is 450 nm;

[0120] A second filtration membrane 102 is arranged in the second filter 12, and the pore size of the second filtration membrane 102 is 220 nm;

[0121] The pore size of the ultrafiltration membrane 201 is 3 nm;

[0122] The first filtration membrane 101 and the second filtration membrane 102 are both located at the bottom of the first filter 11 and the second filter 12, the ultrafiltration membrane 201 is located at the middle position of the ultrafiltration assembly 2, the nano flower-shaped covalent organic framework material 202 is filled below the ultrafiltration membrane 201, and the filling capacity of the nano flower-shaped covalent organic framework material 202 is 1 / 2 of the ultrafiltration assembly 2;

[0123] The first filtration membrane 101, the second filtration membrane 102 and the ultrafiltration membrane 201 are fixed in the first filter 11, the second filter 12 and the ultrafiltration assembly 2 by a threaded and screwed sealing mode.

[0124] The first filter membrane 101 and the second filter membrane 102 in the embodiment are commercially available filter membranes, and the ultrafiltration membrane 201 is a polysulfone-polyethylene glycol membrane, and the preparation method of the polysulfone-polyethylene glycol membrane comprises the following steps:

[0125] S1, under a nitrogen atmosphere, bisphenol A (45.01 g, 0.197 mol), 4,4'-dichlorodiphenyl sulfone (57.82 g, 0.201 mol) and potassium carbonate (82.60 g, 0.598 mol) were dissolved in 500 mL dimethylacetamide (DMAC) and 100 mL toluene under stirring at 500 rpm for 10 min, and then heated to 170℃ to toluene reflux, 10.5 mL of water in the system was removed within 3 h using a Dean-Stark trap, and then the temperature was increased to 190℃ for polymerization for 6 h, then methoxypolyethylene glycol (50.05 g, 0.01 mol) was added and the reaction was continued for 2 h, then the polymerization was stopped after cooling to room temperature, and the reaction was poured into 2 L of 0.4 mol / L HCl aqueous solution, and the solid product was washed with deionized water until the washing liquid was neutral, and then the washed product was dried at 80℃ under -0.01 MPa until the weight was constant, to obtain a polymerization precursor;

[0126] S2, 12 g of the polymerization precursor was dispersed in N-methyl-2-pyrrolidone (NMP, 88 g), heated to 40℃ and stirred at 300 rpm for 12 hours, and then stored in a desiccator for 12 hours to degas at room temperature, to obtain a polymerization liquid;

[0127] S3, the polymerization liquid was cast onto a clean glass plate by a casting knife with a gate height of 250 μm, and then immediately immersed in deionized water at 40±2℃ for 10 min, and then the cooled solid membrane was taken out and placed in fresh deionized water for 2 h to remove residual solvent, and then the solid membrane was annealed in deionized water at 90℃ for 12 h, to obtain the polysulfone-polyethylene glycol membrane.

[0128] The embodiment also provides an application of the water treatment device, and the water treatment device is used for treating wastewater containing uranium, and the BOD5 content of the water treated by the water treatment device is 3 mg / L, the total suspended solids content is 4 mg / L, the dissolved oxygen content is 5 mg / L, the total number of coliform bacteria is 113, and the uranium content is 16 μg / L.

[0129] The adsorption-reduction rate of the nanoflower-shaped covalent organic framework material in the water treatment device to uranium is 97.3%.

[0130] The water treatment device in the embodiment comprises the following steps:

[0131] The uranium-containing wastewater is sequentially introduced into the first filter 11 and the second filter 12 at 5 mL / min, and particles such as suspended matters of >450 nm and >220 nm are sequentially filtered out, and then the uranium-containing wastewater is continuously introduced into the ultrafiltration assembly 2, and after ultrafiltration by the ultrafiltration membrane 201, the treated uranium-containing wastewater is discharged from the water outlet below the ultrafiltration assembly 2.

[0132] In this embodiment, the uranium in the uranium-containing wastewater exists in the form of uranyl ions (UO2 2+ ), is anchored and adsorbed by the carboxyl groups in the nanoflower-shaped covalent organic framework material, and under the action of a reducing agent, the uranyl ions (UO2 2+ ) are reduced to tetravalent uranium (UO2). The loaded metal gold has good electrical conductivity, can accelerate the rate of electron transfer in the reduction process, and can quickly complete the adsorption-reduction process of uranium. The reduced uranium dioxide is deposited at the bottom of the device.

[0133] After the nanoflower-shaped covalent organic framework material is used to treat the uranium-containing wastewater for 6 h at a water flux of 3000, the water treatment device will be blocked due to excessive deposition of uranium dioxide at the bottom of the device, and the nanoflower-shaped covalent organic framework material needs to be eluted with nitric acid solution by opening the ultrafiltration assembly 2. After completion, the nanoflower-shaped covalent organic framework material is used to treat the uranium-containing wastewater again. The adsorption efficiency of the nanoflower-shaped covalent organic framework material is still >90% after repeated use for 6 times. Meanwhile, the adsorption-reduction process of the nanoflower-shaped covalent organic framework material in this embodiment is not affected by other heavy metal ions.

[0134] In the process of adsorption-reduction of uranium in the uranium-containing wastewater by the nanoflower-shaped covalent organic framework material, the lower limit of the uranium content is 240 ppb.

[0135] As Figure 1 and 2 are the transmission electron microscopy images of the flower-shaped covalent organic framework material and the single flower-shaped covalent organic framework material described in Embodiment 1. It can be seen from the images that the material has a uniform spherical, flower-shaped structure (without loading metal).

[0136] As Figure 3 is the transmission electron microscopy image of the nanoflower-shaped covalent organic framework material (single) described in Embodiment 1. The metal loaded on the surface of the flower-shaped structure can be clearly seen in the image.

[0137] As Figure 4 and 5 are the structural schematic diagram and the synthesis structural schematic diagram of the nanoflower-shaped covalent organic framework material described in Embodiment 1.

[0138] As Figure 6 and 7For the X-ray diffraction pattern of the nanoflower-shaped covalent organic framework material and the carboxyl nanoflower-shaped covalent organic framework material described in this embodiment 1, the (100) and (200) crystal planes corresponding to the covalent organic framework appear at 2.79° and 5.58 in the figure, and a weak (111) crystal plane of metallic gold appears at 38.23°. Because the loading amount of gold is small, it is not obvious in the XRD figure.

[0139] As Figure 8 For the infrared spectrum of the nanoflower-shaped covalent organic framework material and the carboxyl nanoflower-shaped covalent organic framework material described in this embodiment 1, the stretching vibration peak of C-O bond appears at 1265±0.01 cm -1 in the figure, the stretching vibration peak of C=C bond appears at 1650±0.01 cm -1 in the figure, the stretching vibration peak of C-O bond appears at 1725±0.01 cm -1 in the figure, and the stretching vibration peak of -OH bond appears at 3420±0.01 cm -1 in the figure.

[0140] As Figure 9 For the reduction reaction kinetics diagram of the nanoflower-shaped covalent organic framework material described in this embodiment 1, the material can achieve more than 90% of the uranium reduction rate within 10 minutes in the process of simulating static catalytic reduction experiment, and the adsorption-reduction efficiency is high. After 30 minutes, the reduction rate can reach more than 97%, which significantly improves the adsorption-reduction rate of the material to uranium.

[0141] As Figure 10 For the specific surface area diagram of the material at each stage in this embodiment 1, it can be seen from the figure that the specific surface area of the nanoflower-shaped covalent organic framework material prepared in this embodiment 1 is large, reaching 2103 m 2 / g, which is higher than that of conventional covalent organic materials. Figure 1 and 2 Together, it can be seen that the flower-shaped morphology has an effect on the increase of the specific surface area, and the specific surface area decreases after further addition and loading, but the active groups and active sites for uranium increase correspondingly.

[0142] Embodiment 2

[0143] This embodiment provides a nanoflower-shaped covalent organic framework material, which is prepared by using an amino compound and an aldehyde compound through a catalyst and a regulator to obtain a covalent organic framework with a flower-shaped structure, and then adding a carboxyl compound and loading metal ions to obtain a nanoflower-shaped covalent organic framework material loaded with metal ions.

[0144] The specific surface area (BET value) of the nanoflower-shaped covalent organic framework material is 736 m 2 / g, and the pore volume is 0.95 cm3 / g, the average pore size is 2.65 nm; after soaking in acidic conditions, the specific surface area, pore volume and pore size are unchanged after soaking in alkaline conditions and after being placed at a high temperature of 200℃.

[0145] The embodiment also provides a preparation method of the nanoflower-shaped covalent organic framework material, comprising the following steps:

[0146] Step 1, 14.16 mg (0.04 mmol) of 1,3,5-tris (4-aminophenyl) benzene and 11.12 mg (0.06 mmol) of 2,5-divinyl-1,4-benzene dialdehyde are dispersed in 5 mL of acetonitrile under stirring at 400 rpm for 20 min, 0.2 mL of scandium trifluoromethanesulfonate and 0.024 mL of aniline are added, and after ultrasonic treatment for 8 min, the temperature is increased to 40℃, and reaction is performed for 75 h, after the reaction is completed, the solid product I is separated by centrifugation, the solid product I is washed with tetrahydrofuran and ethanol for 3 times respectively, and then dried at 70℃ under 0.08 MPa for 18 h to obtain the flower-shaped covalent organic framework material;

[0147] Step 2, 0.12 g of the flower-shaped covalent organic framework material, 0.14 g of 2,3-dimercaptosuccinic acid and 0.015 g of azobisisobutyronitrile are dispersed in 10 mL of N,N-dimethylformamide under stirring at 400 rpm for 20 min, and then placed in a nitrogen atmosphere, the temperature is increased to 90℃, and reaction is continuously performed under stirring at 400 rpm for 2.5 d, after the reaction is completed, the solid product II is separated by centrifugation, the solid product II is washed with acetone and ethanol for 5 times respectively, and then dried at 70℃ under 0.08 MPa for 15 h to obtain the carboxyl flower-shaped covalent organic framework material;

[0148] Step 3, 0.2 g of the carboxyl flower-shaped covalent organic framework material is dispersed in 52.5 mL of tetrahydrofuran under stirring at 400 rpm for 20 min, 3.75 mL of 0.1 wt% of a tetrachlorogold acid solution is added, after mechanical shaking for 4 h under light shielding conditions, 15 mL of a 13.3 mg / L sodium borohydride solution (solvent: tetrahydrofuran) is added, and then reaction is continuously performed under shaking in the dark for 3 h, the shaking frequency is 50 times / min, after washing with acetone and ethanol for 4 times respectively, drying is performed at 80℃ under -0.1 MPa for 8 h to obtain the nanoflower-shaped covalent organic framework material.

[0149] The embodiment also provides a water treatment device comprising the nanoflower-shaped covalent organic framework material, and the water treatment device is consistent with the embodiment 1.

[0150] In the embodiment, the first filter membrane 101 and the second filter membrane 102 are both commercially available filter membranes, and the ultrafiltration membrane 201 is a polysulfone-polyethylene glycol membrane, and the preparation method of the polysulfone-polyethylene glycol membrane is consistent with the embodiment 1.

[0151] The embodiment also provides an application of the water treatment device, and the water treatment device is used for treating uranium-containing sewage, and the BOD5 content of the water treated by the water treatment device is 4 mg / L, the total suspended substance content is 4 mg / L, the dissolved oxygen content is 4 mg / L, the total coliform group number is 115, and the uranium content is 27 μg / L.

[0152] The adsorption-reduction rate of the nanoflower-shaped covalent organic framework material to uranium in the water treatment device is 96.5%.

[0153] The treatment method of the water treatment device in the embodiment is consistent with that in embodiment 1.

[0154] Embodiment 3

[0155] The embodiment provides a nanoflower-shaped covalent organic framework material, which is prepared by using an amino compound and an aldehyde-based compound, and is obtained by catalysis of a catalyst and regulation of a regulator, and then is obtained by addition of a carboxyl compound and loading of metal ions.

[0156] The specific surface area (BET value) of the nanoflower-shaped covalent organic framework material is 650 m 2 / g, the pore volume is 0.98 cm 3 / g, and the average pore size is 2.31 nm; after soaking in an acidic condition, the specific surface area, the pore volume and the pore size are unchanged after soaking in an alkaline condition and after being placed at a high temperature of 200 ℃.

[0157] The embodiment also provides a preparation method of the nanoflower-shaped covalent organic framework material, which comprises the following steps.

[0158] Step 1, 14.16 mg (0.04 mmol) of 1,3,5-tris (4-aminophenyl) benzene and 11.12 mg (0.06 mmol) of 2,5-divinyl-1,4-benzene dialdehyde are dispersed in 5 mL of acetonitrile under stirring at 300 rpm for 10 min, 0.3 mL of acetic acid and 0.024 mL of aniline are added, ultrasonic treatment is performed for 5 min, then the temperature is increased to 30 ℃, and reaction is performed for 72 h; after the reaction is completed, a solid product I is separated by centrifugation, the solid product I is washed with tetrahydrofuran and ethanol for three times respectively, and then is dried at 60 ℃ and under-0.1 MPa for 12 h, to obtain a nanoflower-shaped covalent organic framework material.

[0159] Step 2, 0.12 g of the flower-shaped covalent organic framework material, 0.14 g of 2,3-dimercaptosuccinic acid and 0.015 g of azobisisobutyronitrile were dispersed in 10 mL of N,N-dimethylformamide under stirring at 300 rpm for 10 min, and then placed in a nitrogen atmosphere, heated to 80℃, and continued to be stirred at 300 rpm for 2 d to react, and then the solid product II was separated by centrifugation, and then washed with acetone and ethanol for 3 times respectively, and then dried at 60℃ under-0.1 MPa for 12 h to obtain a carboxyl flower-shaped covalent organic framework material;

[0160] Step 3, 0.1 g of the carboxyl flower-shaped covalent organic framework material was dispersed in 52.5 mL of tetrahydrofuran under stirring at 300 rpm for 10 min, and then 3.75 mL of a 0.1 wt% tetrachlorogold acid solution was added, and then mechanically shaken for 3 h under light shielding, and then 15 mL of a 13.3 mg / L sodium borohydride solution (solvent: tetrahydrofuran) was added, and then the shaking was continued for 3 h in the dark, and the shaking frequency was 60 times / min, and then washed with acetone and ethanol for 3 times respectively, and then dried at 60℃ under-0.1 MPa for 12 h to obtain the nano flower-shaped covalent organic framework material.

[0161] The embodiment also provides a water treatment device comprising the nano flower-shaped covalent organic framework material, and the water treatment device is consistent with that in Embodiment 1.

[0162] The first filter membrane 101 and the second filter membrane 102 in the embodiment are both commercially available filter membranes, and the ultrafiltration membrane 201 is a polysulfone-polyethylene glycol membrane, and the preparation method of the polysulfone-polyethylene glycol membrane is consistent with that in Embodiment 1.

[0163] The embodiment also provides an application of the water treatment device, and the water treatment device is used for treating wastewater containing uranium, and the content of BOD5 in the water treated by the water treatment device is 3 mg / L, the content of total suspended solids is 3 mg / L, the content of dissolved oxygen is 4 mg / L, the total number of coliform bacteria is 112, and the content of uranium is 21 μg / L.

[0164] The adsorption-reduction rate of the nano flower-shaped covalent organic framework material to uranium in the water treatment device is 96.8%.

[0165] The treatment method of the water treatment device in the embodiment is consistent with that in Embodiment 1.

[0166] Comparative Example 1

[0167] This comparative example provides a nano-covalent organic framework material, which is prepared by catalyst catalysis of amino compounds and aldehyde compounds to obtain a covalent organic framework, and then by addition with carboxyl compounds and loading metal ions to obtain a metal-loaded nano-covalent organic framework material.

[0168] The specific surface area (BET value) of the nano-covalent organic framework material is 14 m². 2 / g, pore volume is 0.43cm³ 3 / g, with an average pore size of 2.44nm.

[0169] This comparative example also provides a method for preparing the aforementioned nano-covalent organic framework material, comprising the following steps:

[0170] Step 1: 14.16 mg (0.04 mmol) of 1,3,5-tris(4-aminophenyl)benzene and 11.12 mg (0.06 mmol) of 2,5-divinyl-1,4-phenylenedialdehyde were dispersed in 5 mL of acetonitrile by stirring at 300 rpm for 10 min. 0.3 mL of acetic acid was added, and the mixture was sonicated for 5 min. The temperature was then raised to 30 °C and reacted for 72 h. After the reaction was completed, the solid product was separated by centrifugation. The solid product was washed three times with tetrahydrofuran and ethanol, respectively, and then dried at 60 °C and -0.1 MPa for 12 h to obtain a covalent organic framework material.

[0171] Step 2: Disperse 0.12g of the covalent organic framework material, 0.14g of 2,3-dimercaptosuccinic acid, and 0.015g of azobisisobutyronitrile in 10mL of N,N-dimethylformamide under a nitrogen atmosphere for 10min. Then, continue stirring at 300rpm for 2d to carry out the reaction. After the reaction is completed, centrifuge to separate the solid product II. Wash the solid product II with acetone and ethanol three times each, and dry it at 60℃ and -0.1MPa for 12h to obtain the carboxyl covalent organic framework material.

[0172] Step 3: Disperse 0.1g of the carboxyl covalent organic framework material in 52.5mL of tetrahydrofuran by stirring at 300rpm for 10min. Add 3.75mL of 0.1wt% tetrachloroauric acid solution. After mechanical shaking for 3h in the dark, add 15mL of 13.3mg / L sodium borohydride solution (solvent: tetrahydrofuran). Continue shaking for 3h in the dark, with a shaking frequency of 60 times / min. Wash three times with acetone and ethanol respectively. Dry at 60℃ and -0.1MPa for 12h to obtain the nano-covalent organic framework material.

[0173] The comparative example also provides a water treatment device comprising the nano covalent organic framework material, which is consistent with example 1.

[0174] The first filter membrane 101 and the second filter membrane 102 in the comparative example are both commercially available filter membranes, and the ultrafiltration membrane 201 is a polysulfone-polyethylene glycol membrane, the preparation method of which is consistent with example 1.

[0175] The comparative example also provides an application of the water treatment device, which is used for treating wastewater containing uranium, and the content of BOD5 in the water treated by the water treatment device is 4 mg / L, the content of total suspended solids is 5 mg / L, the content of dissolved oxygen is 4 mg / L, the total number of coliform bacteria is 113, and the content of uranium is 78 μg / L.

[0176] The adsorption-reduction rate of the nano covalent organic framework material in the water treatment device to uranium is 86.8%.

[0177] The treatment method of the water treatment device in the comparative example is consistent with example 1.

[0178] As Figure 12 The scanning electron microscope image of the nano covalent organic framework material in comparative example 1 is shown in the figure, and the morphology of the material is spherical structure, but there is no flower-like morphology.

[0179] Comparative example 2

[0180] The comparative example provides a nano flower-like covalent organic framework material, which is prepared by using an amino compound and an aldehyde compound, a catalyst and a regulator to obtain a covalent organic framework with a flower-like structure, and then loading metal ions to obtain a nano flower-like covalent organic framework material loaded with metal ions.

[0181] The specific surface area (BET value) of the nano flower-like covalent organic framework material is 1001 m 2 / g, the pore volume is 1.35 cm 3 / g, and the average pore size is 5.25 nm.

[0182] The comparative example also provides a preparation method of the nano flower-like covalent organic framework material, which comprises the following steps:

[0183] Step 1, 14.16 mg (0.04 mmol) of 1,3,5-tris (4-aminophenyl) benzene and 11.12 mg (0.06 mmol) of 2,5-divinyl-1,4-benzene dialdehyde were dispersed in 5 mL of acetonitrile under stirring at 300 rpm for 10 min, 0.3 mL of acetic acid and 0.024 mL of aniline were added, and after ultrasonic treatment for 5 min, the temperature was raised to 30℃ and reacted for 72 h. After the reaction was completed, the solid product I was separated by centrifugation, and then washed with tetrahydrofuran and ethanol for 3 times respectively, and then dried at 60℃ under-0.1 MPa for 12 h to obtain a flower-shaped covalent organic framework material;

[0184] Step 2, 0.1 g of the flower-shaped covalent organic framework material was dispersed in 52.5 mL of tetrahydrofuran under stirring at 300 rpm for 10 min, 3.75 mL of 0.1 wt% tetrachloroauric acid solution was added, and after mechanical shaking for 3 h in the dark, 15 mL of 13.3 mg / L sodium borohydride solution (solvent: tetrahydrofuran) was added, and the shaking was continued in the dark for 3 h, and the frequency of shaking was 60 times / min. After washing with acetone and ethanol for 3 times respectively, drying was carried out at 60℃ under-0.1 MPa for 12 h to obtain the nano-flower-shaped covalent organic framework material.

[0185] The present comparative example also provides a water treatment device comprising the nano-flower-shaped covalent organic framework material, which is consistent with Example 1.

[0186] The first filter membrane 101 and the second filter membrane 102 in the present comparative example are both commercially available filter membranes, and the ultrafiltration membrane 201 is a polysulfone-polyethylene glycol membrane, and the preparation method of the polysulfone-polyethylene glycol membrane is consistent with that of Example 1.

[0187] The present comparative example also provides an application of the water treatment device, and the water treatment device is used for treating wastewater containing uranium. After the water treatment device is used, the content of BOD5 in the treated water is 4 mg / L, the content of total suspended solids is 4 mg / L, the content of dissolved oxygen is 5 mg / L, the number of total coliform group is 111, and the content of uranium is 112 μg / L.

[0188] The adsorption-reduction rate of the nano-flower-shaped covalent organic framework material in the water treatment device to uranium is 81.1%.

[0189] The treatment method of the water treatment device in the present comparative example is consistent with that of Example 1.

[0190] Comparative Example 3

[0191] The comparative example provides a nanoflower-shaped covalent organic framework material, which is prepared by using an amino compound and an aldehyde-based compound as raw materials, a catalyst and a regulator to obtain a covalent organic framework with a flower-shaped structure, and then adding a carboxyl compound to obtain the nanoflower-shaped covalent organic framework material.

[0192] The specific surface area (BET value) of the nanoflower-shaped covalent organic framework material is 1328 m 2 / g, the pore volume is 1.15 cm 3 / g, and the average pore size is 3.71 nm.

[0193] The comparative example also provides a preparation method of the nanoflower-shaped covalent organic framework material, which comprises the following steps:

[0194] Step 1: 14.16 mg (0.04 mmol) of 1,3,5-tris (4-aminophenyl) benzene and 11.12 mg (0.06 mmol) of 2,5-divinyl-1,4-benzene dialdehyde are dispersed in 5 mL of acetonitrile under stirring at 300 rpm for 10 min, 0.3 mL of acetic acid and 0.024 mL of aniline are added, and after ultrasonic treatment for 5 min, the temperature is raised to 30℃ and the reaction is carried out for 72 h. After the reaction is completed, the solid product I is separated by centrifugation, and then washed with tetrahydrofuran and ethanol for 3 times respectively, and dried at 60℃ under -0.1 MPa for 12 h to obtain a flower-shaped covalent organic framework material.

[0195] Step 2: 0.12 g of the flower-shaped covalent organic framework material, 0.14 g of 2,3-dimercaptosuccinic acid and 0.015 g of azobisisobutyronitrile are dispersed in 10 mL of N,N-dimethylformamide under stirring at 300 rpm for 10 min, and then placed in a nitrogen atmosphere, the temperature is raised to 80℃, and the reaction is carried out under stirring at 300 rpm for 2 d. After the reaction is completed, the solid product II is separated by centrifugation, and then washed with acetone and ethanol for 3 times respectively, and dried at 60℃ under -0.1 MPa for 12 h to obtain a nanoflower-shaped covalent organic framework material.

[0196] The comparative example also provides a water treatment device comprising the nanoflower-shaped covalent organic framework material, which is consistent with example 1.

[0197] The first filter membrane 101 and the second filter membrane 102 in the comparative example are both commercially available filter membranes, and the ultrafiltration membrane 201 is a polysulfone-polyethylene glycol membrane, and the preparation method of the polysulfone-polyethylene glycol membrane is consistent with that of example 1.

[0198] The comparative example also provides an application of the water treatment device, the water treatment device is used for treating wastewater containing uranium, and the BOD5 content of water treated by the water treatment device is 4 mg / L, the total suspended substance content is 4 mg / L, the dissolved oxygen content is 4 mg / L, the total coliform group number is 114, and the uranium content is 205 μg / L.

[0199] The adsorption rate of the nanoflower-shaped covalent organic framework material in the water treatment device to uranium is 65.4%.

[0200] The treatment method of the water treatment device in the comparative example is consistent with that in example 1.

[0201] Comparative example 4

[0202] The comparative example provides a nanometer covalent organic framework material, the nanometer covalent organic framework material is prepared by an amino compound and an aldehyde compound through a catalyst and a regulator to obtain a covalent organic framework with a structure, then through addition with a carboxyl compound, and loading of metal ions to obtain a nanometer covalent organic framework material loaded with metal ions;

[0203] The specific surface area (BET value) of the nanometer covalent organic framework material is 18 m 2 / g, the pore volume is 0.45 cm 3 / g, and the average pore size is 5.38 nm.

[0204] The comparative example also provides a preparation method of the nanometer covalent organic framework material, including the following steps:

[0205] Step 1, 14.16 mg (0.04 mmol) of 1,3,5-tris (4-aminophenyl) benzene and 11.12 mg of tri-aldehyde-based phloroglucinol are dispersed in 5 mL of acetonitrile under stirring at 300 rpm for 10 min, 0.3 mL of acetic acid and 0.024 mL of aniline are added, ultrasonic treatment is performed for 5 min, then the temperature is raised to 30°C, reaction is performed for 72 h, after the reaction is completed, a solid product I is separated by centrifugation, the solid product I is washed with tetrahydrofuran and ethanol for 3 times respectively, then drying is performed at 60°C and -0.1 MPa for 12 h, to obtain a covalent organic framework material;

[0206] Step 2, 0.12 g of the covalent organic framework material, 0.14 g of 2,3-dimercaptosuccinic acid and 0.015 g of azobisisobutyronitrile are dispersed in 10 mL of N,N-dimethylformamide under stirring at 300 rpm for 10 min, then the system is placed in a nitrogen atmosphere, the temperature is raised to 80°C, and reaction is continuously performed under stirring at 300 rpm for 2 d, after the reaction is completed, a solid product II is separated by centrifugation, the solid product II is washed with acetone and ethanol for 3 times respectively, then drying is performed at 60°C and -0.1 MPa for 12 h, to obtain a carboxyl covalent organic framework material;

[0207] Step 3, 0.1 g of the carboxyl covalent organic framework material was dispersed in 52.5 mL of tetrahydrofuran under stirring at 300 rpm for 10 min, 3.75 mL of 0.1 wt% tetrachloroauric acid solution was added, after mechanical shaking for 3 h in the dark, 15 mL of 13.3 mg / L sodium borohydride solution (solvent: tetrahydrofuran) was added, and the reaction was continued under shaking in the dark for 3 h at a frequency of 60 times / min. After washing with acetone and ethanol for 3 times respectively, the nanoscale covalent organic framework material was obtained by drying at 60 °C under -0.1 MPa for 12 h.

[0208] The present comparative example also provides a water treatment device comprising the nanoscale covalent organic framework material, which is consistent with Example 1.

[0209] The first filter membrane 101 and the second filter membrane 102 in the present comparative example are both commercially available filter membranes, and the ultrafiltration membrane 201 is a polysulfone-polyethylene glycol membrane, the preparation method of which is consistent with that of Example 1.

[0210] The present comparative example also provides an application of the water treatment device, which is used for treating wastewater containing uranium. After treatment by the water treatment device, the content of BOD5 in the water is 3 mg / L, the content of total suspended solids is 4 mg / L, the content of dissolved oxygen is 5 mg / L, the number of total coliform group is 115, and the content of uranium is 246 μg / L.

[0211] The adsorption-reduction rate of the nanoscale covalent organic framework material in the water treatment device for uranium is 58.5%.

[0212] The treatment method of the water treatment device in the present comparative example is consistent with that of Example 1.

[0213] As Figure 13 The scanning electron microscope image of the nanoscale covalent organic framework material in Comparative Example 4 is also spherical agglomerate morphology.

[0214] Table 1 is the properties of the materials in the present example and comparative examples

[0215]

[0216] Table 2 is the performance of wastewater filtration in the present example and comparative examples

[0217]

[0218] As shown in Tables 1 and 2, the nanoflower-shaped covalent organic framework material in the embodiment has high porosity, and due to the flower-shaped structure, the specific surface area of the material is correspondingly increased, the ultrafiltration membrane is used for treating the wastewater containing uranium, the content of bacteria and suspended solids in the water is significantly reduced, uranium is adsorbed and reduced in a targeted manner, and the problem of uranium residue in the wastewater is solved.

[0219] In the comparative example 1, no aniline is added as a regulator, so that the morphology of the finally prepared material is not a flower-shaped structure, the specific surface area and the like are greatly reduced, and the effect when applied to wastewater treatment is also correspondingly poor. In the comparative example 2, no carboxyl compound is added, so that the response to uranium is weakened, and the adsorption rate of uranium is also reduced. In the comparative example 3, no metal gold is coordinated, so that the adsorption-reduction rate of uranium is relatively reduced. In the comparative example 4, the monomer is replaced, so that the flower-shaped structure cannot be generated, the effect when the metal is loaded is relatively poor, and the adsorption of uranium is also weakened.

[0220] In the application, the analysis method of the five-day biochemical oxygen demand (BOD5) content in the data test of the seawater before and after being separated by the ultrafiltration membrane is the five-day culture method, the analysis method of the total suspended solids content is the weight method, the detection limit is 2 mg / L, and the analysis standard conforms to the HY 003.4-91; the analysis method of the dissolved oxygen content is the iodimetric titration method, the detection limit is 0.042 mg / L, and the analysis standard conforms to the GB 12763.4-91; and the analysis method of the total coliform group number is the filter membrane method, and the analysis standard conforms to the HY 003.9-91.

[0221] The specific conditions of soaking under the acidic condition are soaking in aqua regia for 24 h, the specific conditions of soaking under the alkaline condition are soaking in NaOH with pH = 11 for 24 h, and the time of placing at 200 DEG C high temperature is 48 h.

[0222] According to the above, the nanoflower-shaped covalent organic framework material has a very wide range of use, low cost and high market prospect.

[0223] The above is only a preferred embodiment of the application, and does not limit the application in any other form, and any modification or equivalent change made according to the technical essence of the application still falls within the scope of the application.

Claims

1. A nanoflower-like covalent organic framework material, characterized in that, The nanoflower-like covalent organic framework material is prepared by catalysis and regulation of amino compounds and aldehyde compounds to obtain a covalent organic framework with a flower-like structure. Then, it is obtained by addition with carboxyl compounds and loading metal ions to obtain a metal-loaded nanoflower-like covalent organic framework material. The specific surface area of ​​the nanoflower-like covalent organic framework material is 650-750 m². 2 / g, pore volume is 0.93-0.99cm³ 3 / g, with an average pore size of 2.30-2.70nm; after soaking under acidic conditions, soaking under alkaline conditions, and placing at 200℃, the specific surface area, pore volume, and pore size remain unchanged; The preparation method of the nanoflower-like covalent organic framework material includes the following steps: Step 1: The amino compound and aldehyde compound are stirred and dispersed in organic solvent one, a catalyst and a regulator are added, and after ultrasonic dispersion, the mixture is heated to carry out the reaction. After the reaction is completed, the solid product one is separated by centrifugation. The solid product one is washed and dried to obtain the flower-like covalent organic framework material. Step 2: The flower-like covalent organic framework material, carboxyl compound and initiator are stirred and dispersed in organic solvent II, and then placed under nitrogen atmosphere. After heating, stirring is continued to carry out the reaction. After the reaction is completed, the solid product II is separated by centrifugation. The solid product II is washed and dried to obtain carboxyl flower-like covalent organic framework material. Step 3: The carboxyl flower-like covalent organic framework material is stirred and dispersed in organic solvent three, a metal compound is added, and mechanical shaking is performed under light-protected conditions. Then, a reducing agent is added, and the reaction is continued under dark conditions. After the reaction is completed, the solid product three is separated by centrifugation. The solid product three is washed and dried to obtain the nano-flower-like covalent organic framework material. The regulator in step 1 is aniline; The molar ratio of the amino compound and the aldehyde compound in step 1 is (2:3) - (3:2). The amino compound in step 1 is 1,3,5-tris(4-aminophenyl)benzene; The aldehyde compound in step 1 is 2,5-divinyl-1,4-phenylenedialdehyde; The carboxyl compound in step 2 is 2,3-dimercaptosuccinic acid; The metal in the metal compound in step 3 is one or more of the following: iron, cobalt, nickel, copper, zinc, tin, platinum, palladium, silver, and gold.

2. The nanoflower-like covalent organic framework material according to claim 1, characterized in that, The nanoflower-like covalent organic framework material is located at 1265±0.01 cm⁻¹ in the infrared spectrum. -1 The peak corresponding to the stretching vibration of the CO bond is 1650±0.01cm. -1 The peak corresponding to the stretching vibration of the C=C bond is 1725±0.01cm. -1 The peak corresponding to the stretching vibration of the CO bond is 3420±0.01cm. -1 The peak corresponds to the stretching vibration of the -OH bond.

3. The nanoflower-like covalent organic framework material according to claim 1, characterized in that, The nanoflower-like covalent organic framework material exhibits (100) and (200) crystal planes corresponding to the covalent organic framework at 2.79° and 5.58° in X-ray diffraction, and a faint (111) crystal plane of metallic gold appears at 38.23°.

4. A method for preparing the nanoflower-like covalent organic framework material according to any one of claims 1-3, characterized in that, Includes the following steps: Step 1: The amino compound and aldehyde compound are stirred and dispersed in organic solvent one, a catalyst and a regulator are added, and after ultrasonic dispersion, the mixture is heated to carry out the reaction. After the reaction is completed, the solid product one is separated by centrifugation. The solid product one is washed and dried to obtain the flower-like covalent organic framework material. Step 2: The flower-like covalent organic framework material, carboxyl compound and initiator are stirred and dispersed in organic solvent II, and then placed under nitrogen atmosphere. After heating, stirring is continued to carry out the reaction. After the reaction is completed, the solid product II is separated by centrifugation. The solid product II is washed and dried to obtain carboxyl flower-like covalent organic framework material. Step 3: The carboxyl flower-like covalent organic framework material is stirred and dispersed in organic solvent three. A metal compound is added, and the mixture is mechanically shaken under light-protected conditions. Then, a reducing agent is added, and the mixture is shaken and reacted under dark conditions. After the reaction is completed, the solid product three is separated by centrifugation. The solid product three is washed and dried to obtain the nano-flower-like covalent organic framework material.

5. The preparation method according to claim 4, characterized in that, In step 1, the volume ratio of the regulator to the organic solvent is (0.02-0.025):

5.

6. The preparation method according to claim 4, characterized in that, In step 2, the mass ratio of the flower-like covalent organic framework material, the carboxyl compound, and the initiator is (0.12-0.13):(0.13-0.15):(0.01-0.015).

7. The preparation method according to claim 4, characterized in that, In step 3, the volume ratio of the metal compound to the organic solvent is (3-4):(50-53).

8. A water treatment device comprising the nanoflower-like covalent organic framework material according to any one of claims 1-3, characterized in that, The water treatment device includes a filtration assembly (1) and an ultrafiltration assembly (2). The filtration assembly (1) includes a first filter (11) and a second filter (12). The ultrafiltration assembly (2) includes an ultrafiltration membrane (201) and the nanoflower-like covalent organic framework material (202). The first filter (11), the second filter (12), and the ultrafiltration component (2) are all top-in, bottom-out structures; The first filter (11), the second filter (12), and the ultrafiltration assembly (2) are connected by a pipe; The first filter (11) is provided with a first filter membrane (101), and the pore size of the first filter membrane (101) is 400-500nm; The second filter (12) is provided with a second filter membrane (102), the pore size of the second filter membrane (102) being 200-300nm; The pore size of the ultrafiltration membrane (201) is 2-5 nm; The first filter membrane (101) and the second filter membrane (102) are both located at the bottom of the first filter (11) and the second filter (12). The ultrafiltration membrane (201) is located at 1 / 4-3 / 4 of the ultrafiltration module (2). The nano-flower-like covalent organic framework material (202) is filled below the ultrafiltration membrane (201). The volume of the nano-flower-like covalent organic framework material (202) is 1 / 4-3 / 4 of the volume of the ultrafiltration module (2). The first filter membrane (101), the second filter membrane (102) and the ultrafiltration membrane (201) are fixed in the first filter (11), the second filter (12) and the ultrafiltration assembly (2) by a threaded tightening seal.

9. An application of the water treatment apparatus according to claim 8, characterized in that, The water treatment device is used to treat uranium-containing wastewater. The water treated by the water treatment device has a BOD5 content of 3-4 mg / L, a total suspended solids content of 3-4 mg / L, a dissolved oxygen content of 4-5 mg / L, a total coliform count of 112-115, and a uranium content of 15-30 μg / L. The adsorption-reduction rate of uranium by the nano-flower-like covalent organic framework material in the water treatment device is 96.5-97.5%.

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