A puf / cof composite material, a preparation method and application thereof

Abstract

The present application relates to the technical field of materials, and particularly relates to a PUF / COF composite material, a preparation method and application thereof. The present application provides a preparation method of a PUF / COF composite material, comprising the following steps: A) mixing aldehyde ligands, amino ligands and a solvent to obtain a ligand solution; the aldehyde ligands comprise di-valent or more poly-aldehyde ligands; the amino ligands comprise di-valent or more poly-amino ligands; at least one of the aldehyde ligands and the amino ligands is tri-valent or more; B) mixing the ligand solution with polyurethane foam (PUF) to obtain a PUF adsorption solution; C) mixing the PUF adsorption solution with an organic acid solution, and reacting under the condition of ultraviolet light irradiation to obtain a PUF / COF composite material. The PUF / COF composite material prepared by the present application has excellent urea adsorption performance and cycle use stability, can be applied to blood purification adsorption, and can be recycled and reused.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of materials, in particular to a PUF / COF composite material, a preparation method and application thereof. BACKGROUND

[0002] In the field of blood purification, hyperuremia is a symptom of high urea content in blood caused by kidney failure. In the blood of uremia patients, the concentration of urea is the highest, and if no kidney dialysis treatment is performed, it may lead to organ failure and death, so it is crucial to remove urea. However, it takes as long as 4 hours to remove high-concentration urea, so developing a technology that can remove more urea in a shorter time can truly help improve the quality of life of patients. Urea removal can take many forms, and adsorption is one of them. In the prior art, urea adsorption is mainly performed by passing a solution through an adsorption bed of adsorption material, but this method has the disadvantage of low adsorption rate, so it is crucial to find high-efficiency adsorption material.

[0003] Polyurethane (PU) refers to a high molecular compound containing repeating -NHCOO- groups in the high molecular backbone, which has very wide applications and can be made into plastics, rubber, fiber, paint, adhesive, etc. Polyurethane foam (PUF) has been used as a separation and enrichment material in analytical chemistry for several decades. Polyurethane foam has the characteristics of elasticity, controllable pore structure, adjustable shape, simple preparation process, fast adsorption and desorption rate, etc., which makes PUF very suitable for use as an adsorption material, but its pore is usually large, and the adsorption effect on some small molecules (such as urea) is not good.

[0004] Therefore, many materials are introduced, such as activated carbon, zeolite, transition metal carbide / nitride material (MXene) of two-dimensional layered structure, metal organic framework (MOFs) and the like (Chem. Eng. J. 2010, 326, 1145-1158; Micropor. Mesopor. Mat. 2002, 145, 157-164; J. Colloid Interface Sci. 2010, 500, 88-95.). Among them, MOFs are of great concern compared with other materials due to controllable active sites, regular and ordered channels and large specific surface area. However, MOFs mainly exist in the form of powder, which is difficult to separate from the liquid medium after adsorption. In order to separate from the liquid medium without causing secondary pollution, many scholars combine MOF nanoparticles with functional matrix. In the prior art, Li et al. (J. Colloid Interface Sci. 2018, 527, 267-279.) successfully prepared Zr-MOFs-PU foam film for dye adsorption, but the following shortcomings exist: ① the preparation process is complicated; ② in addition, the pretreatment of chromic acid (strong oxidizing acid) to improve the adhesion and wettability in the preparation process causes partial collapse of the PU foam; ③ in addition, most MOFs materials cause destruction of the MOFs structure in the aqueous environment, which is difficult to repeatedly cycle and apply (J. Mater. Chem. A 2017, 5, 18770-18776.). SUMMARY

[0005] Therefore, the technical problem to be solved by the present application is to provide a PUF / COF composite material, a preparation method and application thereof. The PUF / COF composite material prepared by the present application has excellent urea adsorption performance and cycle stability, and can be applied to blood purification adsorption.

[0006] The present application provides a preparation method of a PUF / COF composite material, comprising the following steps:

[0007] A) mixing an aldehyde-based ligand, an amino ligand and a solvent to obtain a ligand solution;

[0008] The aldehyde-based ligand comprises a polyaldehyde-based ligand with two or more;

[0009] The amino ligand comprises a polyamino ligand with two or more;

[0010] At least one of the aldehyde-based ligand and the amino ligand is three or more;

[0011] B) mixing the ligand solution with a polyurethane foam to obtain a PUF adsorption solution;

[0012] C) mixing the PUF adsorbed solution with an organic acid solution, and reacting under the condition of ultraviolet light irradiation to obtain a PUF / COF composite material.

[0013] Preferably, the aldehyde group ligand comprises at least one of 3,3',5,5'-tetraaldehyde-4,4'-dihydroxydiphenyl, mesitol, p-xylene aldehyde and 1,3,6,8-tetra(4-formaldehyde phenyl)pyrene.

[0014] The amino ligand comprises at least one of diaminobenzene sulfonic acid, p-phenylenediamine, tetra-(4-aminophenyl)ethylene, 3,3'-diaminodiphenyl sulfone, diphenyl[b,d] thiophene-3,7-diamine 5,5-dioxide and 5,5,11,11-tetraoxo-5,11-dihydro-5l6,11l6-dibenzo[d,d']benzo[1,2-b;4,5-b']dithiophene-3,9-diamine.

[0015] Preferably, the molar ratio of the aldehyde group in the aldehyde group ligand and the amino group in the amino ligand is 1:1.05-1.35.

[0016] Preferably, the solvent comprises water, an aqueous solution of ethanol or an aqueous solution of methanol; the mass concentration of the aqueous solution of ethanol is 20%-30%; the mass concentration of the aqueous solution of methanol is 20%-30%.

[0017] In the ligand solution, the total mass content of the aldehyde group ligand and the amino ligand is 5%-10%.

[0018] Preferably, in step A), after the mixing, the method further comprises ultrasonic treatment.

[0019] The power of the ultrasonic treatment is 100-500W, and the time is 3-6min.

[0020] Preferably, in step B), the volume of the polyurethane foam is 1-12cm 3 .

[0021] Preferably, in step C), the organic acid solution is an ice acetic acid solution or an ascorbic acid solution.

[0022] The concentration of the organic acid solution is 1-3mol / L.

[0023] The organic acid solution accounts for 10%-20% of the total volume of the mixed solution.

[0024] Preferably, in step C), the wavelength of the ultraviolet light is 270-320nm; the intensity of the ultraviolet light irradiation is 0.1-0.8W.

[0025] The reaction is carried out at room temperature, and the reaction time is 30-60min.

[0026] The application further provides the PUF / COF composite material prepared by the preparation method.

[0027] The application further provides application of the PUF / COF composite material as blood purification adsorption material.

[0028] The application provides a preparation method of a PUF / COF composite material, comprising the following steps: A) mixing an aldehyde-based ligand, an amino ligand and a solvent to obtain a ligand solution; the aldehyde-based ligand comprises a polyvalent aldehyde-based ligand with two or more; the amino ligand comprises a polyvalent amino ligand with two or more; at least one of the aldehyde-based ligand and the amino ligand is three or more; B) mixing the ligand solution with polyurethane foam (PUF) to obtain a PUF adsorption solution; C) mixing the PUF adsorption solution with an organic acid solution and reacting under the condition of ultraviolet light irradiation to obtain a PUF / COF composite material. The PUF / COF composite material prepared by the application has excellent urea adsorption performance and cycle use stability, can be applied to blood purification adsorption, and can be recycled and reused. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 A mechanism diagram for preparing the PUF / COF composite material is provided for an embodiment of the application;

[0030] Figure 2 A reaction mechanism diagram of ultraviolet light irradiation in step C) is provided for an embodiment of the application. DETAILED DESCRIPTION

[0031] The technical solutions of the application will be described clearly and completely below with reference to the embodiments of the application. Obviously, the described embodiments are only some of the embodiments of the application, but not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0032] The application provides a preparation method of a PUF / COF composite material, comprising the following steps:

[0033] A) mixing an aldehyde-based ligand, an amino ligand and a solvent to obtain a ligand solution;

[0034] The aldehyde-based ligand comprises a polyvalent aldehyde-based ligand with two or more;

[0035] The amino ligand comprises a polyvalent amino ligand with two or more;

[0036] At least one of the aldehyde-based ligand and the amino ligand is three or more;

[0037] B) obtaining a PUF adsorption solution after mixing the ligand solution with a polyurethane foam (PUF);

[0038] C) obtaining a PUF / COF composite material by mixing the PUF adsorption solution with an organic acid solution and reacting under the condition of ultraviolet light irradiation.

[0039] In step A):

[0040] Mixing the aldehyde ligand, the amino ligand and the solvent to obtain a ligand solution.

[0041] The aldehyde ligand includes a polyaldehyde ligand with two or more aldehyde groups; the amino ligand includes a polyamino ligand with two or more amino groups; at least one of the aldehyde ligand and the amino ligand is a ligand with three or more aldehyde groups or amino groups.

[0042] Specifically, the aldehyde ligand is at least one of 3,3',5,5'-tetraaldehyde-4,4'-dihydroxydiphenyl, mesitol, p-xylene aldehyde and 1,3,6,8-tetrakis(4-formaldehyde phenyl)pyrene.

[0043] The amino ligand is at least one of diamino benzene sulfonic acid, p-phenylenediamine, tetra-(4-aminophenyl)ethylene, 3,3'-diaminodiphenyl sulfone, 5,5-dioxide of dibenzo[b,d]thiophene-3,7-diamine (CAS No. 6259-19-4) and 5,5,11,11-tetraoxo-5,11-dihydro-5l6,11l6-dibenzo[d,d']benzo[1,2-b;4,5-b']dithiophene-3,9-diamine.

[0044] The molar ratio of the aldehyde group in the aldehyde ligand to the amino group in the amino ligand is 1:1.05-1.35; for example, 1:1.11, 1:1.22, 1:1.16.

[0045] Both the aldehyde ligand and the amino ligand are dissolved in the solvent.

[0046] The solvent includes water, an aqueous solution of ethanol or an aqueous solution of methanol; the mass concentration of the aqueous solution of ethanol is 20%-30%; the mass concentration of the aqueous solution of methanol is 20%-30%.

[0047] In the ligand solution, the total mass content of the aldehyde ligand and the amino ligand is 5%-10%; for example, 5.32%, 8%, 9.1%, 9%.

[0048] In some embodiments of the present application, the mixing further includes ultrasonic treatment. The ultrasonic treatment is used to accelerate the dissolution. The power of the ultrasonic treatment is 100-500 W, for example, 150 W, 450 W, 250 W; the time is 3-6 min, for example, 6 min, 3 min, 4 min.

[0049] In step B) :

[0050] After mixing the ligand solution with polyurethane foam (PUF), a PUF adsorption solution is obtained.

[0051] In some embodiments of the present application, the volume of the polyurethane foam (PUF) is 1-12 cm 3 .

[0052] In step C) :

[0053] After mixing the PUF adsorption solution with an organic acid solution and reacting under the condition of ultraviolet light irradiation, a PUF / COF composite material is obtained.

[0054] The organic acid solution is an organic non-strong oxidizing weak acid solution; specifically, an ice acetic acid solution or an ascorbic acid solution. The concentration of the organic acid solution is 1-3 mol / L; for example, 1 mol / L, 2 mol / L, or 3 mol / L.

[0055] The organic acid solution accounts for 10%-20% of the total volume of the mixed solution; for example, 11.1%, 16.7%, or 18.6%.

[0056] The wavelength of the ultraviolet light is 270-320 nm; for example, 270 nm, 300 nm, or 320 nm. The intensity of the ultraviolet light irradiation is 0.1-0.8 W; for example, 0.1 W, 0.5 W, or 0.8 W.

[0057] The reaction is carried out at room temperature, and the reaction time is 30-60 min; for example, 30 min, 45 min, or 60 min.

[0058] In some embodiments of the present application, after the reaction, drying is further included. Specifically, the PUF is clamped out with tweezers, and after drying, a PUF / COF composite material is obtained.

[0059] The drying temperature is 40-80℃, and the time is 6-12 h. The drying is carried out in a vacuum oven.

[0060] Figure 1 A mechanism diagram for preparing a PUF / COF composite material is provided for an embodiment of the present application. Specifically, Figure 1 In FIG. (a) of the above formula (I), the amino and aldehyde ligands are first dissolved in a solvent to form an “amino + aldehyde ligand solution” (by adjusting the ratio of the amino and aldehyde ligands, the molar ratio of the amino is made to be more, to create conditions for the formation of an aminated COF later) ; Figure 1In the figure (b) of the figure, the PUF is added into the above-mentioned solution, and the ligand solution enters the inside of the pore channel of the polyurethane by adsorption of the polyurethane (the mesh structure in the figure b is a schematic diagram); Figure 1 In the figure (c) of the figure, the reaction is carried out under acidic conditions, and the edge aminated COF is grown in situ in the inside of the pore channel (the imine bond of the COF itself and the pore channel can be used as an adsorption site of urea, so as to improve the adsorption amount of urea); Figure 1 In the figure (d) of the figure, the chemical bond connected PUF / COF composite material is formed by ultraviolet irradiation.

[0061] Figure 2 The reaction mechanism diagram of the ultraviolet irradiation in step C) provided for an embodiment of the present application is provided. Specifically, Figure 2 In the figure (a) of the figure, under the condition of light irradiation, the electrons of the aminated COF are excited, and the valence band generates a photo-generated hole (h + ) and the conduction band generates a photo-generated electron (e - ) at the same time; Figure 2 In the figure (b) of the figure, the h + can oxidize the ester group in the polyurethane into an aldehyde group, so as to form a new connection site-aldehyde group; the aminated COF under the acidic condition can react with the newly formed aldehyde group of the polyurethane to generate a chemical bond-C=N connection (the newly formed C=N can be used as an adsorption site of urea, so as to further improve the adsorption amount of urea), and further form a more firm PUF / COF composite material. (It is worth noting that when ascorbic acid is used as the acidic system and the aqueous methanol solution is used as the solvent, the light intensity and time should be selected to be the maximum, because at this time the methanol and ascorbic acid can consume a certain amount of holes, so that the concentration of the holes is low, and the light intensity and time should be selected to be the maximum, so as to ensure that there are enough holes to form the connection site).

[0062] The present application also provides a PUF / COF composite material prepared by the preparation method.

[0063] In the PUF / COF composite material, the optical band gap of the COF is 2.0-3.0 eV; such as 2.35 eV, 2.50 eV, 2.68 eV, 2.85 eV.

[0064] The present application also provides an application of the PUF / COF composite material in the field of blood purification, specifically an application as a blood purification adsorption material.

[0065] The raw materials used in the present application are not particularly limited and can be generally commercially available.

[0066] In order to further illustrate the present application, the following embodiments are used to describe the PUF / COF composite material, the preparation method and the application thereof provided by the present application in detail, but it should not be understood as a limitation to the protection scope of the present application.

[0067] Comparative Example 1

[0068] 1) 120 mL of water was added into a beaker, and then 2.80 g of 3,3',5,5'-tetraformyl-4,4'-dihydroxybiphenyl and 3.94 g of diamino benzenesulfonic acid were added, and the obtained mixed solution was ultrasonically treated for 6 min to accelerate dissolution, and the ultrasonic power was 150 W, to obtain a ligand solution; the molar ratio of the aldehyde group in the aldehyde ligand to the amino group in the amino ligand was 1:1.11; and the total mass content of the aldehyde ligand and the amino ligand in the ligand solution was 5.32%;

[0069] 2) 2 cm×2 cm×2 cm of PUF was added into the ligand solution to obtain a PUF adsorption solution;

[0070] 3) 15 mL of 1.0 mol / L glacial acetic acid solution (the glacial acetic acid solution accounted for 11.1% of the total volume of the mixed solution) was added into the PUF adsorption solution, and after reaction for 30 min, the PUF was taken out with tweezers, and was dried in a vacuum oven at 60°C for 6 h to obtain a u-PUF / COF1 composite material (wherein the optical band gap of the COF was 2.35 eV).

[0071] Example 1

[0072] 1) 120 mL of water was added into a beaker, and then 2.80 g of 3,3',5,5'-tetraformyl-4,4'-dihydroxybiphenyl and 3.94 g of diamino benzenesulfonic acid were added, and the obtained mixed solution was ultrasonically treated for 6 min to accelerate dissolution, and the ultrasonic power was 150 W, to obtain a ligand solution; the molar ratio of the aldehyde group in the aldehyde ligand to the amino group in the amino ligand was 1:1.11; and the total mass content of the aldehyde ligand and the amino ligand in the ligand solution was 5.32%;

[0073] 2) 2 cm×2 cm×2 cm of PUF was added into the ligand solution to obtain a PUF adsorption solution;

[0074] 3) 15 mL of 1.0 mol / L glacial acetic acid solution (the glacial acetic acid solution accounted for 11.1% of the total volume of the mixed solution) was added into the PUF adsorption solution, and after reaction for 30 min, the PUF was taken out with tweezers, and was dried in a vacuum oven at 60°C for 6 h to obtain a u-PUF / COF1 composite material (wherein the optical band gap of the COF was 2.35 eV).

[0075] Comparative Example 2

[0076] 1) In a beaker, 40 mL of 20% ethanol aqueous solution was added, then 1.52 g of mesitol and 1.85 g of p-phenylenediamine were added, and the obtained mixed solution was ultrasonically treated for 3 min to accelerate dissolution, with an ultrasonic power of 450 W, to obtain a ligand solution; the molar ratio of aldehyde groups in the aldehyde ligand to amino groups in the amino ligand was 1:1.22; the total mass content of the aldehyde ligand and the amino ligand in the ligand solution was 8.0%;

[0077] 2) In the ligand solution, 1 cm x 1 cm x 1 cm PUF was added to obtain a PUF adsorption solution;

[0078] 3) In the PUF adsorption solution, 8 mL of 2.0 mol / L glacial acetic acid solution (the glacial acetic acid solution accounted for 16.7% of the total volume of the mixed solution) was added, and after 45 min of reaction, the PUF was taken out with tweezers, and was dried in a 40°C vacuum oven for 9 h to obtain a u-PUF / COF2 composite material (wherein the optical band gap of the COF was 2.50 eV).

[0079] Example 2

[0080] 1) In a beaker, 40 mL of 20% ethanol aqueous solution was added, then 1.52 g of mesitol and 1.85 g of p-phenylenediamine were added, and the obtained mixed solution was ultrasonically treated for 3 min to accelerate dissolution, with an ultrasonic power of 450 W, to obtain a ligand solution; the molar ratio of aldehyde groups in the aldehyde ligand to amino groups in the amino ligand was 1:1.22; the total mass content of the aldehyde ligand and the amino ligand in the ligand solution was 8.0%;

[0081] 2) In the ligand solution, 1 cm x 1 cm x 1 cm PUF was added to obtain a PUF adsorption solution;

[0082] 3) In the PUF adsorption solution, 8 mL of 2.0 mol / L glacial acetic acid solution (the glacial acetic acid solution accounted for 16.7% of the total volume of the mixed solution) was added, and after 45 min of reaction at room temperature, the PUF was taken out with tweezers, and was dried in a 40°C vacuum oven for 9 h to obtain a PUF / COF2 composite material (wherein the optical band gap of the COF was 2.50 eV).

[0083] Comparative Example 3

[0084] 1) In a beaker, 70 mL of 30% methanol aqueous solution was added, then 2.58 g of p-xylylene aldehyde and 4.40 g of tetra-(4-aminophenyl) ethylene were added, the obtained mixed solution was ultrasonically treated for 4 min to accelerate dissolution, the ultrasonic power was 250 W, to obtain a ligand solution; the molar ratio of aldehyde groups in the aldehyde ligand to amino groups in the amino ligand was 1:1.16; the total mass content of the aldehyde ligand and the amino ligand in the ligand solution was 9.1%;

[0085] 2) In the ligand solution, 2 cm x 2 cm x 3 cm of PUF was added to obtain a PUF adsorption solution;

[0086] 3) In the PUF adsorption solution, 16 mL of 3.0 mol / L ascorbic acid solution (the ascorbic acid solution accounted for 18.6% of the total volume of the mixed solution) was added, after 60 min of reaction, the PUF was clamped out with tweezers, and was dried in a vacuum oven at 80°C for 12 h to obtain a u-PUF / COF3 composite material (wherein the optical band gap of the COF was 2.68 eV).

[0087] Example 3

[0088] 1) In a beaker, 70 mL of 30% methanol aqueous solution was added, then 2.58 g of p-xylylene aldehyde and 4.40 g of tetra-(4-aminophenyl) ethylene were added, the obtained mixed solution was ultrasonically treated for 4 min to accelerate dissolution, the ultrasonic power was 250 W, to obtain a ligand solution; the molar ratio of aldehyde groups in the aldehyde ligand to amino groups in the amino ligand was 1:1.16; the total mass content of the aldehyde ligand and the amino ligand in the ligand solution was 9.1%;

[0089] 2) In the ligand solution, 2 cm x 2 cm x 3 cm of PUF was added to obtain a PUF adsorption solution;

[0090] 3) In the PUF adsorption solution, 16 mL of 3.0 mol / L ascorbic acid solution (the ascorbic acid solution accounted for 18.6% of the total volume of the mixed solution) was added, after 60 min of reaction at room temperature, the PUF was clamped out with tweezers, and was dried in a vacuum oven at 80°C for 12 h to obtain a PUF / COF3 composite material (wherein the optical band gap of the COF was 2.68 eV).

[0091] Example 4

[0092] The difference from Example 3 is that:

[0093] The 2.58 g of terephthaldehyde in step 1) is replaced by 3.98 g of 1,3,6,8-tetra(4-formaldehyde phenyl)pyrene, and the 4.40 g of tetra-(4-aminophenyl)ethylene is replaced by 2.93 g of tetra-(4-aminophenyl)ethylene; the molar ratio of the aldehyde groups in the aldehyde ligand and the amino groups in the amino ligand is 1:1.16; the total mass content of the aldehyde ligand and the amino ligand in the ligand solution is 9.0%; the remaining steps and parameters are carried out according to Example 3 to obtain a PUF / COF4 composite material (wherein the optical band gap of the COF is 2.85 eV).

[0094] Comparative Example 4

[0095] The difference from Example 3 is that:

[0096] The 4.40 g of tetra-(4-aminophenyl)ethylene in step 1) is replaced by 2.77 g of 3,3'-diaminodiphenyl sulfone, and the 2.58 g of terephthaldehyde is replaced by 1.29 g of terephthaldehyde; the molar ratio of the aldehyde groups in the aldehyde ligand and the amino groups in the amino ligand is 1:1.16; the total mass content of the aldehyde ligand and the amino ligand in the ligand solution is 5.5%; the remaining steps and parameters are carried out according to Example 3 to obtain a PUF / COF5 composite material (wherein the optical band gap of the COF is 2.58 eV).

[0097] Comparative Example 5

[0098] The difference from Example 3 is that:

[0099] The 4.40 g of tetra-(4-aminophenyl)ethylene in step 1) is replaced by 4.58 g of dibenzo[b,d]thiophene-3,7-diamine 5,5-dioxide, and the 2.58 g of terephthaldehyde is replaced by 2.15 g of terephthaldehyde; the molar ratio of the aldehyde groups in the aldehyde ligand and the amino groups in the amino ligand is 1:1.16; the total mass content of the aldehyde ligand and the amino ligand in the ligand solution is 8.7%; the remaining steps and parameters are carried out according to Example 3 to obtain a PUF / COF6 composite material (wherein the optical band gap of the COF is 2.87 eV).

[0100] Comparative Example 6

[0101] The difference from Example 1 is that:

[0102] The 2.80 g 3,3',5,5'-tetraaldehyde-4,4'-dihydroxybiphenyl in step 1) is replaced by 5.12 g 4,4',4',4'-(azure-1,3,5,7-tetrayl) tetrakisbenzaldehyde; the molar ratio of aldehyde groups in the aldehyde ligand and amino groups in the amino ligand is 1:1.11; the total mass content of the aldehyde ligand and the amino ligand in the ligand solution is 7.0%; the remaining steps and parameters are carried out according to Example 1 to obtain a PUF / COF7 composite material (wherein the optical band gap of the COF is 3.12 eV).

[0103] The composite materials obtained in Examples 1-4 and Comparative Examples 1-6 are subjected to the following tests:

[0104] 1. Urea adsorption rate test:

[0105] 1) Standard curve drawing:

[0106] 50 mg of urea is weighed and dissolved in a beaker, and then transferred to a volumetric flask and diluted with water to 1000 mL;

[0107] Each of 0 mL, 10 mL, 20 mL, 30 mL, 40 mL, and 50 mL of the diluent is added with 50 mL, 40 mL, 30 mL, 20 mL, 10 mL, and 0.00 mL of distilled water, respectively, to configure solutions with urea molar concentrations of 0, 10 mg / L, 20 mg / L, 30 mg / L, 40 mg / L, and 50 mg / L, respectively, and mix well to obtain three sets of parallel samples.

[0108] 3 mL of the above solutions with different concentrations are taken and added with 3.00 mL of urea color developing agent into each tube, respectively, and shaken well, and then placed in a 37°C water bath for constant temperature for 15 min;

[0109] After cooling, the solutions are injected into a 1 cm light path cuvette, and the absorbance is measured at a wavelength of 430 nm; the absorbance is taken as the abscissa, and the concentration is taken as the ordinate, and a standard curve is drawn.

[0110] 2) Urea adsorption rate test:

[0111] 2 cm x 2 cm x 2 cm PUF / COF, pure PUF, and u-PUF / COF are added into three 50 mL 50 mg / L urea solutions, respectively, and then shaken at 150 r / min at room temperature for 5 min. Then, the concentration of the remaining urea in the solution is determined by ultraviolet-visible spectrophotometry. The urea adsorption rate A (%) is calculated according to formula (1):

[0112] Removal rate A = (C0-C e ) / C0x100% (1);

[0113] In formula (1), C0(mg / L) and C e(mg / L) are the initial urea concentration and the residual urea concentration, respectively.

[0114] The higher the adsorption rate A is, the better the adsorption rate of the material to urea is.

[0115] 2. Stability test in recycling:

[0116] After the urea-adsorbed material is placed in water for 2h, washed and dried, the adsorption rate test is performed again. We take the urea adsorption rate after 5 cycles as an index to measure the stability of the composite material in recycling, which is measured by index K, calculated according to formula (2). The larger the K value is, the better the stability in recycling is.

[0117]

[0118] In formula (2), A1 represents the first adsorption rate, and A5 represents the adsorption rate after 5 cycles.

[0119] The test results are shown in Table 1.

[0120] Table 1. Test results of urea adsorption rate and stability in recycling

[0121]

[0122]

[0123] The urea adsorption rate test shows that the urea adsorption rate of u-PUF / COF1, u-PUF / COF2 and u-PUF / COF3 composites is significantly improved compared with pure PUF: the urea adsorption rate A increases from 1.2% to about 60%, which is mainly due to the synergistic effect of the three-dimensional carrier channel transmission of PUF and the uniform pore of COF; the urea adsorption rate of PUF / COF1, PUF / COF2 and PUF / COF3 is further improved compared with u-PUF / COF1, u-PUF / COF2 and u-PUF / COF3: the urea adsorption rate A increases from about 60% to about 90%, which is mainly because the chemical bond formed after light irradiation as an active adsorption site increases the adsorption of urea.

[0124] The urea adsorption rate of PUF / COF4 does not change significantly compared to that of PUF / COF3, while the urea adsorption rates of PUF / COF5 and PUF / COF6 decrease significantly compared to that of PUF / COF3, because: the aldehyde group monomer of PUF / COF4 changes from binary to quaternary, and the aldehyde group ligand and the amino group ligand can form a COF with rich pore structure, that is, it meets the condition that at least one of the aldehyde group ligand and the amino group ligand is ternary or more; while PUF / COF5 and PUF / COF6 are just the opposite, that is, it cannot meet the condition that at least one of the aldehyde group ligand and the amino group ligand is ternary or more, and the prepared COF has few channels, so the urea adsorption rate decreases significantly.

[0125] The recycling stability test shows that after 5 cycles, the K value of PUF / COF1, PUF / COF2 and PUF / COF3 is 99%, which can maintain stable adsorption rate; while the K value of u-PUF / COF1, u-PUF / COF2 and u-PUF / COF3 is stable at about 40%, and the recycling stability decreases significantly, which is mainly caused by the COF falling off from the pores of PUF in the recycling process, while the COF in PUF / COF does not fall off due to the existence of chemical bond between COF and PUF, so the stability is good and the reuse is strong.

[0126] The recycling stability K of PUF / COF4, PUF / COF5 and PUF / COF6 relative to the recycling stability K of PUF / COF3 has almost no change, because: after ultraviolet irradiation, the COF and PUF in the above three and PUF / COF3 do not fall off due to the existence of chemical bond between COF and PUF, so the stability is good and the reuse is strong.

[0127] The urea adsorption rate A and the recycling stability K value of PUF / COF7 decrease significantly compared to those of PUF / COF1, which is mainly because: the change of the type of aldehyde group ligand of PUF / COF7 leads to that the band gap (3.12 eV) of the formed COF cannot meet the condition of forming new active adsorption sites and connection sites under light, that is, it cannot form new active adsorption sites and connection sites under ultraviolet irradiation, so the urea adsorption rate and the recycling stability decrease compared to PUF / COF1.

[0128] The above description of the examples is merely intended to help understand the method of the present application and its core idea. Various modifications to these examples will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other examples without departing from the spirit or scope of the present application. Thus, the present application is not to be limited to the examples shown herein but is to accord with the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a PUF / COF composite material, comprising the following steps: A) mixing an aldehyde ligand, an amino ligand and a solvent to obtain a ligand solution; the aldehyde ligand comprises at least one of 3,3',5,5'-tetraaldehyde-4,4'-dihydroxydiphenyl, mesitol, terephthaldehyde and 1,3,6,8-tetrakis(4-formaldehyde phenyl)pyrene; the amino ligand comprises at least one of diaminobenzenesulfonic acid, p-phenylenediamine, tetra-(4-aminophenyl)ethylene, 3,3'-diaminodiphenyl sulfone, dibenzo[b,d]thiophene-3,7-diamine 5,5-dioxide and 5,5,11,11-tetraoxo-5,11-dihydro-5l6,11l6-dibenzo[d,d']benzo[1,2-b;4,5-b']dithiophene-3,9-diamine; at least one of the aldehyde ligand and the amino ligand is more than three; a molar ratio of aldehyde groups in the aldehyde ligand to amino groups in the amino ligand is 1:1.05-1.35; B) mixing the ligand solution with a polyurethane foam to obtain a PUF adsorption solution; C) mixing the PUF adsorption solution with an organic acid solution and reacting under the condition of ultraviolet light irradiation to obtain a PUF / COF composite material; a wavelength of the ultraviolet light is 270-320 nm; an intensity of the ultraviolet light irradiation is 0.1-0.8 W; the reaction is carried out at room temperature, and a reaction time is 30-60 min.

2. The production method according to claim 1, characterized by, the solvent comprises water, an aqueous solution of ethanol or an aqueous solution of methanol; a mass concentration of the aqueous solution of ethanol is 20%-30%; a mass concentration of the aqueous solution of methanol is 20%-30%; a total mass content of the aldehyde ligand and the amino ligand in the ligand solution is 5%-10%.

3. The preparation method according to claim 1, characterized in that, in step A), the mixing further comprises ultrasonic treatment; a power of the ultrasonic treatment is 100-500 W, and a time is 3-6 min.

4. The method of claim 1, wherein, In step B), the polyurethane foam has a volume of 1 to 12 cm 3 .

5. The preparation method according to claim 1, characterized in that, in step C), the organic acid solution is an ice acetic acid solution or an ascorbic acid solution; a concentration of the organic acid solution is 1-3 mol / L; the organic acid solution accounts for 10%-20% of a total volume of the mixed solution. 6.A PUF / COF composite material prepared by the method of any one of claims 1-5. 7.Use of the PUF / COF composite material of claim 6 as a blood purification adsorption material.

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