A method for preparing hierarchical porous composite materials using waste masks and MOFs

Abstract

The application discloses a method for preparing hierarchical porous composite materials by using waste masks and MOFs, and comprises the following steps: (1) dissolving a metal precursor in a solvent and uniformly dispersing to obtain solution A; (2) dissolving an organic ligand in the solution A and uniformly dispersing to obtain solution B; (3) transferring the solution B into a hydrothermal kettle, and then fixing the waste masks in the solution B in the hydrothermal kettle; and (4) placing the hydrothermal kettle into an oven to perform a hydrothermal reaction, and finally obtaining the hierarchical porous composite materials. The hierarchical porous composite materials can simultaneously realize the interception and filtration of microplastics with particle sizes of centimeter level, millimeter level, micrometer level and nanometer level in water bodies, so that the effective management of water body environmental pollution can be realized.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for preparing hierarchical porous composite materials using waste masks and MOFs. BACKGROUND

[0002] Microplastics are usually referred to as plastic particles with a particle size of less than 5 mm. Microplastic pollution is widespread and has been detected in soil and water bodies. Microplastic particles are small, providing the possibility of being phagocytosed by organisms, and are ideal carriers for many hydrophobic organic pollutants and heavy metals, increasing the possibility of release of plastic additives or chemical substances adsorbed on microplastics into the ingested organisms. Microplastic pollution has become one of the global environmental pollution problems. Although most of the plastic fragments generated during the waste plastic recycling process are utilized, a small amount of fragments still enters the sewage treatment plant with the production wastewater of the workshop. At present, sewage treatment plants mainly aim at the removal of COD Cr , BOD5, TN and TP in water, and there is no treatment link for microplastics in water, so microplastics still exist in wastewater, leading to the discharge of microplastics from sewage treatment plants into rivers and oceans, thereby causing pollution of water bodies in the natural environment.

[0003] The structure of a disposable ordinary mask mainly includes a mask body, an elastic band and a nose bridge, wherein the mask body is a non-woven fabric composed of high-flow polypropylene resin, the elastic band is an elastic body hanging rope composed of polyurethane, and the nose bridge is composed of a metal wire and polypropylene resin. Except for the nose bridge which is difficult to recycle due to the presence of metal wire, the remaining parts can be recycled and reused.

[0004] Metal-organic framework (MOF) is a new material that emerged and rapidly developed in recent years. Because of its diverse structure, unique performance, large specific surface area and porosity, it is widely used in energy storage, adsorption, electromagnetic shielding, wave absorption and other fields, and has made good progress.

[0005] The mesh size of the PP fibers that make up the non-woven fabric of the mask body of the waste mask is 0.5-30 microns, so the original waste mask can only intercept and filter microplastics with a particle size greater than 0.5 microns in water. For microplastics with a particle size less than 0.5 microns, especially nanoscale microplastics, cannot be intercepted and filtered.

[0006] Therefore, how to simultaneously achieve the interception and filtration of microplastics with particle sizes of centimeter, millimeter, micron and nanometer levels in water is a technical problem to be solved by the present application. SUMMARY

[0007] The present application is to solve the problems existing in the prior art and provide a method for preparing hierarchical porous composite materials by using waste masks and MOFs, which organically combines the treatment of microplastics in wastewater with the treatment of waste masks, reduces waste mask pollution, effectively removes microplastic pollutants in wastewater, and realizes the interception and filtration of microplastics with particle sizes of centimeter, millimeter, micron and nanometer in water bodies.

[0008] The technical scheme adopted by the present application is:

[0009] A method for preparing hierarchical porous composite materials by using waste masks and MOFs, comprising the following steps:

[0010] 1) Dissolve the metal precursor in the solvent and disperse uniformly to obtain solution A;

[0011] 2) Dissolve the organic ligand in solution A and disperse uniformly to obtain solution B;

[0012] 3) Transfer solution B into an autoclave, fix the waste mask in solution B in the autoclave, and place the autoclave in an oven for hydrothermal reaction;

[0013] 4) After hydrothermal reaction, wash with DMF and ethanol in sequence to finally obtain the hierarchical porous composite material.

[0014] Further, the solvent in step 1) is water or DMF.

[0015] Further, the metal precursor in step 1) is one or more of zinc nitrate hexahydrate, cobalt nitrate hexahydrate, nickel nitrate hexahydrate, copper nitrate trihydrate, and bismuth nitrate pentahydrate.

[0016] Further, the concentration of the metal precursor in the solvent is 0.001-0.5 mol / L.

[0017] Further, the organic ligand in step 2) is one or more of 2-methylimidazole, terephthalic acid, and trimesic acid.

[0018] Further, the concentration of the organic ligand in solution A is 0.008-4.0 mol / L.

[0019] Further, in step 3), the mass ratio of the metal precursor to the waste mask is (0.01-10):(90-99.99), the temperature of the hydrothermal reaction is 100-300℃, and the time is 60-1200 min.

[0020] Further, both step 1) and step 2) use ultrasonic dispersion, and the ultrasonic dispersion time is 5-100 min and the power is 50-950 W.

[0021] The present application has the following advantages:

[0022] 1) When adsorbing microplastics, the mesh size of the PP fibers of the non-woven fabric of the waste mask body is 0.5-30 microns, so it can intercept and filter microplastics with a particle size greater than 0.5 microns in the water body. The MOF material loaded on the mask body is a nanomaterial itself, with nanopores, which can adsorb nanoparticles, thereby intercepting and filtering microplastics with a particle size of 50-500 nanometers in the water body. In addition, it has no selectivity for the type and particle size of microplastics, and can achieve broad-spectrum absorption, thereby effectively managing water environmental pollution.

[0023] 2) The raw materials of the hierarchical porous composite material of the present application are derived from waste masks, which improves the recycling efficiency of waste and promotes the recycling of resources; the raw material cost is low, thereby reducing the total cost of preparing the composite material of the present application and facilitating large-scale production.

[0024] 3) The method of the present application is simple, and does not require additional disinfection and sterilization treatment of the waste mask. The high-temperature melting stage can simultaneously complete the uniform mixing of the raw materials and the disinfection and sterilization of the raw materials. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 SEM images of the hierarchical porous composite material in Example 1 intercepting and filtering micron and nanometer microplastics.

[0026] a: waste mask body intercepting and filtering micron microplastics, b: mask body loaded with cobalt MOF intercepting and filtering nanometer microplastics. DETAILED DESCRIPTION

[0027] The following will be described in conjunction with the accompanying Figure 1 Further description of the present application.

[0028] Example 1

[0029] A method for preparing a hierarchical porous composite material using waste masks and MOF, comprising the following steps:

[0030] 1) Dissolve cobalt nitrate hexahydrate in DMF solvent, and the concentration of cobalt nitrate hexahydrate dissolved in DMF solvent is 0.02 mol / L; then uniformly ultrasonic disperse for 20 min at a power of 200 W to obtain solution A.

[0031] 2) Dissolve phthalic acid in solution A, and the concentration of phthalic acid in solution A is 0.16 mol / L; then uniformly ultrasonic disperse for 10 min at a power of 100 W to obtain solution B.

[0032] 3) Solution B was transferred into the hydrothermal kettle, and the waste mask was fixed in solution B in the hydrothermal kettle, and the mass ratio of cobalt nitrate hexahydrate to waste mask was (1) : (99); the hydrothermal kettle was placed in an oven for hydrothermal reaction, and the temperature of the hydrothermal reaction was 120℃, and the time was 480 min.

[0033] 4) After reaction, DMF and ethanol were used for cleaning in sequence, and finally the hierarchical porous composite material was obtained.

[0034] Example 2

[0035] The preparation method of this example was the same as that of Example 1, except that zinc nitrate hexahydrate and nickel nitrate hexahydrate (molar ratio 1:1) were used as metal precursors in this example; the concentration of the metal precursor was 0.03 mol / L; the ultrasonic dispersion time was 15 min, and the power was 150 W.

[0036] 2-methylimidazole was used as an organic ligand, and the concentration of the organic ligand was 0.24 mol / L; the ultrasonic dispersion time was 18 min, and the power was 130 W.

[0037] The mass ratio of the metal precursor to the waste mask in step (3) was (2) : (98); the temperature of the hydrothermal reaction was 150℃, and the time was 600 min.

[0038] Example 3

[0039] The preparation method of this example was the same as that of Example 1, except that copper nitrate hexahydrate was used as a metal precursor in this example; the concentration of the metal precursor was 0.04 mol / L; the ultrasonic dispersion time was 20 min, and the power was 300 W.

[0040] Benzenetricarboxylic acid was used as an organic ligand, and the concentration of the organic ligand was 0.32 mol / L; the ultrasonic dispersion time was 25 min, and the power was 400 W.

[0041] The mass ratio of the metal precursor to the waste mask in step (3) was (0.1) : (99.9); the temperature of the hydrothermal reaction was 180℃, and the time was 720 min.

[0042] Comparative Example

[0043] The waste mask of this comparative example was not loaded with any MOF material.

[0044] The removal rates of micron-sized and nano-sized microplastics in wastewater were measured for the above three examples and one comparative example. The wastewater containing microplastics was taken from a sewage treatment plant, and the free COD Cr , BOD5, TN and TP in the wastewater had been effectively removed.

[0045] The removal rate of microplastics in the micron level was measured, and the total initial concentration of microplastics (polyethylene, polypropylene and polystyrene) in the wastewater was 1000 pieces / L, and the particle size range was 0.5-30 microns. The treatment results of microplastics in wastewater are shown in Table 1.

[0046] Table 1 Removal rate of microplastics in wastewater in the micron level in the examples and comparative examples

[0047]

[0048] As shown in Table 1, after loading MOF on the discarded mask, the MOF on the PP fiber has a certain interface interaction with the microplastics in water, and can adsorb a small amount of microplastics, so the removal rate of microplastics is increased.

[0049] The removal rate of nanoscale microplastics was measured, and the total initial concentration of microplastics (polyethylene, polypropylene and polystyrene) in the wastewater was 1000 pieces / L, and the particle size range was 50-500 nm. The treatment results of microplastics in wastewater are shown in Table 2.

[0050] Table 2 Removal rate of nanoscale microplastics in wastewater in the examples and comparative examples

[0051]

[0052] As shown in Table 2, after loading MOF on the discarded mask, the nanopores of the MOF material itself have an interception and filtration effect on the nanoscale microplastics in water, so the adsorption amount is significantly increased, and the removal rate of microplastics in water reaches more than 85%. The discarded mask of the comparative example does not have MOF material, so it cannot intercept and filter nanoscale microplastics.

[0053] Figure 1 SEM images of the hierarchical porous composite material intercepting and filtering microscale and nanoscale microplastics in Example 1. In the figure, a: discarded mask body intercepting and filtering microscale microplastics, b: mask body loaded with cobalt MOF intercepting and filtering nanoscale microplastics.

[0054] The above only describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements without departing from the principles of the present application, and these improvements should also be considered as the protection scope of the present application.

Claims

1. A method for preparing hierarchical porous composite materials using discarded face masks and MOFs, characterized in that: Includes the following steps: 1) Dissolve the metal precursor in a solvent and disperse it evenly to obtain solution A; 2) Dissolve the organic ligand in solution A and disperse it evenly to obtain solution B; 3) Transfer solution B to the hydrothermal reactor, then fix the discarded mask in solution B in the hydrothermal reactor, and place the hydrothermal reactor in an oven to carry out the hydrothermal reaction; 4) After the hydrothermal reaction, the material was washed sequentially with DMF and ethanol to obtain a hierarchical porous composite material. The solvent mentioned in step 1) is water or DMF; The metal precursor mentioned in step 1) is one or more of the following: zinc nitrate hexahydrate, cobalt nitrate hexahydrate, nickel nitrate hexahydrate, copper nitrate trihydrate, and bismuth nitrate pentahydrate; In step 3), the mass ratio of the metal precursor to the discarded mask is (0.01-10):(90-99.99), the hydrothermal reaction temperature is 100-300℃, and the time is 60-1200min; The organic ligand mentioned in step 2) is one or more of 2-methylimidazole, terephthalic acid, and trimesic acid; The obtained hierarchical porous composite material can simultaneously intercept and filter microplastics in water with particle sizes of centimeter, millimeter, micrometer and nanometer.

2. The method for preparing hierarchical porous composite materials using discarded masks and MOFs as described in claim 1, characterized in that: The concentration of the metal precursor in the solvent is 0.001-0.5 mol / L.

3. The method for preparing hierarchical porous composite materials using discarded masks and MOF as described in claim 1, characterized in that: The concentration of the organic ligand in solution A is 0.008-4.0 mol / L.

4. The method for preparing hierarchical porous composite materials using discarded masks and MOFs as described in claim 1, characterized in that: Both steps 1) and 2) employ ultrasonic dispersion, with a dispersion time of 5-100 min and a power of 50-950 W.

Images