Nested porous scaffold material as well as preparation method and application thereof

Abstract

The invention provides a nested porous scaffold material as well as a preparation method and application thereof, and belongs to the technical field of ceramic materials. A particle structure material which does not hinder pore penetration is embedded in the pore structure of the porous scaffold material, so that effective contact between liquid and the wall surface of the material can be improved when the liquid passes through the interior of the porous scaffold material, substance exchange between the material and the liquid is improved, and adsorption of heavy metal ions, organic dyes and the like is more facilitated. Different materials can be selected as the porous scaffold material so as to meet different use requirements. Meanwhile, the porous scaffold material is simple in process and easy for industrial production. Therefore, the porous scaffold material disclosed by the invention has a good application prospect in the fields of sewage treatment and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of ceramic materials, and particularly relates to a nested porous scaffold material, a preparation method thereof and uses thereof. Background Art

[0002] With the accelerated development of industrialization and modernization, the problem of environmental pollution has become increasingly prominent, seriously threatening human life safety and social economy. As a relatively serious form of environmental pollution, water pollution is mainly caused by the discharge of wastewater, waste residue, etc. generated in industrial production, agricultural production and urban life into water. Due to its rich three-dimensional through-hole structure and large specific surface area, porous scaffold materials have been widely used in the fields of environmental adsorption, water pollution treatment, etc.

[0003] Currently, the methods for preparing porous scaffold materials include the foaming method, the template method, the pore-forming agent method, etc. The pore size of the porous scaffold obtained by the foaming method is difficult to control, and the connectivity between macropores is relatively low. The pore-forming agent method is to mix the pore-forming agent with the slurry to form a scaffold model, and then remove the pore-forming agent by dissolution or calcination to obtain a porous material. Existing porous scaffold materials are difficult to prepare various composite forms of materials and cannot organically combine materials with different characteristics.

[0004] In addition, during the fluid contact application process of the through-structure of the porous scaffold, due to hydrodynamic factors, the flow velocity of the liquid in contact with the inner wall of the scaffold is relatively low, and it tends to flow through the middle of the pores, which is not conducive to the mass transfer between the material and the liquid, thereby reducing the reaction efficiency, the adsorption effect of heavy metal ions, etc., and thus is not conducive to the effective treatment of water pollutants.

[0005] It can be seen that the existing prepared porous scaffold system can be further optimized in terms of material combination and structural configuration to meet its application in the field of sewage treatment, etc. Summary of the Invention

[0006] The purpose of the present invention is to provide a nested porous scaffold material, a preparation method thereof and uses thereof.

[0007] The present invention provides a preparation method of a nested porous scaffold material, which comprises the following steps:

[0008] (1) Add ceramic powder A and ceramic powder B into an aqueous alginate solution respectively, and after uniform dispersion, obtain ceramic slurry A and ceramic slurry B;

[0009] (2) Drop ceramic slurry A into an aqueous calcium ion solution to crosslink and form spherical ceramic particles;

[0010] (3) Stack the spherical ceramic particles obtained in step (2) in a mold, inject the ceramic slurry B in step (1) into the mold to submerge the ceramic particles, and then transfer the whole to an aqueous calcium ion solution for crosslinking and molding. After drying, a green body is obtained;

[0011] (4) Calcine and sinter the green body obtained in step (3) to obtain the product.

[0012] Furthermore,

[0013] In step (1), the concentration of the aqueous alginate solution is 1-2 wt%;

[0014] And / or, in step (1), ceramic powder A and ceramic powder B are the same or different ceramic materials, and the obtained ceramic slurry A has a lower concentration than ceramic slurry B;

[0015] Preferably,

[0016] In step (1), ceramic powder A and ceramic powder B are each independently selected from one or more powders of hydroxyapatite, diatomite, bentonite, and kaolin;

[0017] And / or, in step (1), the concentrations of ceramic slurry A and ceramic slurry B are 5-40 wt%.

[0018] Furthermore,

[0019] Ceramic powder A is hydroxyapatite and ceramic powder B is hydroxyapatite;

[0020] Or, ceramic powder A is bentonite and ceramic powder B is diatomite;

[0021] Or, ceramic powder A is bentonite and ceramic powder B is hydroxyapatite.

[0022] Furthermore,

[0023] Ceramic powder A is hydroxyapatite, the concentration of ceramic slurry A is 5 wt%, ceramic powder B is hydroxyapatite, and the concentration of ceramic slurry B is 15 wt%;

[0024] Or, ceramic powder A is bentonite, the concentration of ceramic slurry A is 7 wt%, ceramic powder B is diatomite, and the concentration of ceramic slurry B is 20 wt%;

[0025] Or, ceramic powder A is bentonite, the concentration of ceramic slurry A is 5 wt%, ceramic powder B is hydroxyapatite, and the concentration of ceramic slurry B is 15 wt%.

[0026] Furthermore, the particle sizes of ceramic powder A and ceramic powder B are ≤10 μm.

[0027] Furthermore, in step (2) and step (3), the calcium ion aqueous solution is obtained by dissolving calcium chloride or calcium nitrate in water, and the concentration of calcium ions is 0.5 to 2 wt%, preferably 1 wt%.

[0028] Furthermore, in step (3), the spherical ceramic particles are molded when they are accumulated in the mold so that the particles are in surface contact with each other;

[0029] And / or, in step (3), the drying temperature is 40 to 100° C.;

[0030] And / or, in step (4), the calcination temperature is 500-600° C., and / or, the calcination time is 1-10 h;

[0031] And / or, in step (4), the sintering temperature is 800-1200° C., and / or, the sintering time is 2-3 hours.

[0032] The present invention also provides a nested porous scaffold material, which is prepared by the above-mentioned preparation method.

[0033] Furthermore, the pore structure of the nested porous scaffold material has small ceramic particles embedded therein, which do not hinder the inter-pore structure and do not fall off from the porous structure.

[0034] The present invention also provides the use of the aforementioned nested porous scaffold material in sewage treatment;

[0035] Preferably, the nested porous scaffold material is used for adsorbing heavy metal ions and organic dyes in a solution.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) In the preparation method of the present invention, the spherical ceramic core serves as both a pore-forming agent for the porous scaffold and a core material for the nested structure, without the need to introduce additional materials to form pores;

[0038] (2) The present invention prepares a nested porous scaffold material that can freely combine different materials. Under the premise of not hindering its permeability, particles of different materials and sizes are embedded in the pores of the porous scaffold, so that different combinations of porous materials can be achieved to meet different needs.

[0039] (3) The embedded particles in the porous structure of the nested stent regulate the flow rate of the fluid when the fluid flows through the porous stent, change the dispersion of the fluid flow field, increase the effective contact between the fluid and the stent wall, and help improve the material exchange between the material and the fluid.

[0040] (4) The nested porous scaffold material of the present invention has a simple process, low requirements for equipment, high production efficiency, high possibility of industrial production, and does not require additional chemical cross-linking agents.

[0041] In summary, the present invention provides a nested porous scaffold material. In the pore structure of the porous scaffold material, a particulate structural material that does not hinder the penetration of pores is embedded, enabling the liquid to increase the effective contact with the material wall when passing through the inside of the porous scaffold material, improving the mass transfer between the material and the fluid, and being more conducive to the adsorption of heavy metal ions, organic dyes, etc. The porous scaffold material of the present invention can select different materials to meet different usage requirements. At the same time, the process of the porous scaffold material is simple and easy for industrial production. Therefore, the porous scaffold material of the present invention has good application prospects in the fields of sewage treatment and the like.

[0042] Obviously, based on the above content of the present invention, according to the common general technical knowledge and conventional means in the art, without departing from the above basic technical idea of the present invention, various other forms of modifications, substitutions, or changes can be made.

[0043] The following is a further detailed description of the above content of the present invention through specific embodiments in the form of examples. However, this should not be construed as limiting the scope of the above subject matter of the present invention to the following examples. All technologies implemented based on the above content of the present invention fall within the scope of the present invention. Description of the Drawings

[0044] Figure 1 Micro-CT images of the nested porous hydroxyapatite scaffold for Example 1: a is the overall view; b is the cross-sectional view.

[0045] Figure 2 Stereomicroscope images of the nested porous composite scaffolds prepared in Example 2 and Example 3: a is the nested porous bentonite-diatomite composite scaffold; b is the nested porous bentonite-hydroxyapatite composite scaffold.

[0046] Figure 3 Stereomicroscope images of the nested porous composite scaffolds prepared in Comparative Examples 1-4: a is the nested bentonite scaffold; b is the nested diatomite-hydroxyapatite composite scaffold; c is the nested hydroxyapatite-bentonite composite scaffold; d is the porous hydroxyapatite scaffold.

[0047] Figure 4 Schematic diagrams of the pore structures of the nested scaffold and the porous scaffold and the fluid passing through: a is the nested scaffold, b is the porous scaffold; the arrow represents the liquid flow direction, and the triangle represents the adsorbed substance. Detailed Description of the Embodiments

[0048] The raw materials and equipment used in the specific implementation of the present invention are all known products, which are obtained by purchasing commercially available products.

[0049] Example 1. Preparation of nested porous hydroxyapatite scaffold

[0050] (1) Preparation of ceramic slurry: Take 5 g of hydroxyapatite powder and add deionized water to 100 mL. Under stirring, add 1.0 g of sodium alginate. After complete dissolution and uniform mixing, a ceramic slurry with a mass-to-volume ratio of 5% is obtained. In the same process, replace the above 5 g of hydroxyapatite powder with 15 g of hydroxyapatite powder to prepare a ceramic slurry with a mass-to-volume ratio of 15%.

[0051] (2) Take the ceramic slurry with a mass-to-volume ratio of 5%. At room temperature, form droplets by dripping freely through a 20 ml syringe needle into a calcium chloride aqueous solution with a mass-to-volume ratio of 1% to form spherical sodium alginate-hydroxyapatite gel particles. Filter out the gel particles and wash with deionized water to remove residual calcium chloride.

[0052] (3) Filter out the spherical sodium alginate-hydroxyapatite gel particles. Place the filtered particles on filter paper to remove the remaining moisture on the particle surface, and transfer them to a mold for molding by pressing. Close packing occurs with face-to-face contact. Inject the ceramic slurry with a mass-to-volume ratio of 15% prepared in step (1) into the particle packing mold to immerse the particles, and then soak in a calcium chloride aqueous solution with a mass-to-volume ratio of 1% for gel solidification. Take out the gel solid and wash with deionized water to remove residual calcium chloride, and further dry at 40 °C to obtain a green body of a nested porous material containing hydroxyapatite slurry.

[0053] (4) The green body of the nested porous material containing hydroxyapatite slurry is calcined at 500 °C for 1 hour to thermally remove organic substances, and then heated up and sintered at 1100 °C for 2 hours, and cooled with the furnace to obtain a nested porous hydroxyapatite scaffold. The Micro-CT image of this scaffold is as Figure 1 shown. In the figure, the orange color is the porous scaffold structure, and the white particles are ceramic particles. As Figure 1 can be seen, the pore structure of the porous scaffold is embedded with ceramic particles. It can be seen from the cross-sectional structure diagram that the ceramic particle structures are evenly distributed in the pores inside and outside the scaffold.

[0054] Example 2. Preparation of nested porous bentonite-diatomite composite scaffold

[0055] (1) Preparation of ceramic slurry: Take 7 g of bentonite powder and add deionized water to 100 mL. Under stirring, add 1.0 g of sodium alginate. After complete dissolution and uniform mixing, a bentonite slurry with a mass-to-volume ratio of 7% is obtained. In the same process, replace the above 7 g of bentonite powder with 20 g of diatomite to prepare a diatomite slurry with a mass-to-volume ratio of 20%.

[0056] (2) Take a bentonite slurry with a mass-to-volume ratio of 7%, and at room temperature, form droplets that freely drip one by one through a 20 ml syringe needle into a calcium chloride aqueous solution with a mass-to-volume ratio of 1% to form spherical sodium alginate-bentonite gel particles. Filter out the gel particles, and wash them with deionized water to remove the residual calcium chloride.

[0057] (3) Filter out the spherical sodium alginate-bentonite gel particles, place the filtered particles on filter paper to remove the remaining moisture on the particle surface, and transfer them to a mold for molding by pressing. Close packing occurs with surface-to-surface contact. Inject the diatomite slurry with a mass-to-volume ratio of 20% prepared in step (1) into the particle packing mold to immerse the particles, and then soak them in a calcium chloride aqueous solution with a mass-to-volume ratio of 1% for gel solidification. Take out the gel solidified body and wash it with deionized water to remove the residual calcium chloride, and further dry it at 40 °C to obtain a nested porous material green body containing diatomite slurry.

[0058] (4) The nested porous material green body containing diatomite slurry is calcined at 500 °C for 1 hour to thermally remove organic substances, and then the temperature is raised and sintered at 900 °C for 2 hours, and cooled with the furnace to obtain a nested porous composite scaffold with bentonite particles embedded in a porous diatomite scaffold. The solid diagram of this scaffold is as shown in Figure 2 Figure a, and it can be seen from Figure 2 Figure a that the overall structure of the porous composite scaffold is complete, with a uniform spherical pore structure, and there are through holes between the pores; the bentonite particles remain within the porous structure of the diatomite after sintering, and one bentonite particle is retained in each pore, and the particles have a certain active space without hindering the penetration of the pore structure.

[0059] Example 3. Preparation of a nested porous bentonite-hydroxyapatite composite scaffold

[0060] (1) Prepare ceramic slurries: Take 5 g of bentonite powder, add deionized water to 100 mL, and add 1.0 g of sodium alginate under stirring. After complete dissolution and uniform mixing, a bentonite slurry with a mass-to-volume ratio of 5% is obtained. In the same process, replace the above 5 g of bentonite powder with 15 g of hydroxyapatite to prepare a hydroxyapatite slurry with a mass-to-volume ratio of 15%.

[0061] (2) Take a bentonite slurry with a mass-to-volume ratio of 5%, and at room temperature, form droplets that freely drip one by one through a 20 ml syringe needle into a calcium chloride aqueous solution with a mass-to-volume ratio of 1% to form spherical sodium alginate-bentonite gel particles. Filter out the gel particles, and wash them with deionized water to remove the residual calcium chloride.

[0062] (3) Filter out the spherical sodium alginate-bentonite gel particles, place the filtered particles on filter paper to remove the remaining moisture on the particle surface, and transfer them to a mold for molding by pressing. Close packing occurs with surface-to-surface contact. Inject the hydroxyapatite ceramic slurry with a mass-volume ratio of 15% prepared in step (1) into the particle packing mold to immerse the particles, and then soak them in a calcium chloride aqueous solution with a mass-volume ratio of 1% for gel solidification. Take out the gel solid and wash it with deionized water to remove the residual calcium chloride, and further dry it at 40 °C to obtain a nested porous material green body.

[0063] (4) Bake the obtained green body at 500 °C for 1 hour to thermally remove the organic matter, then raise the temperature and sinter it at 1100 °C for 2 hours, and cool it down with the furnace to obtain a nested porous composite scaffold with hydroxyapatite porous scaffolds nested with bentonite particles. The solid diagram of this scaffold is as Figure 2 shown in Figure 2 b. It can be seen from

[0064] Comparative Example 1: Preparation of bentonite scaffold

[0065] (1) Prepare the ceramic slurry: Take 10 g of bentonite powder and add deionized water to 100 mL. Stir and add 1.0 g of sodium alginate. Wait until it is completely dissolved and mixed evenly to obtain a bentonite slurry with a mass-volume ratio of 10%. In the same process, replace the above 10 g of bentonite powder with 15 g of bentonite powder to prepare a bentonite slurry with a mass-volume ratio of 15%.

[0066] (2) Take the bentonite slurry with a mass-volume ratio of 10%. At room temperature, form droplets one by one by dripping freely through a 20 ml syringe needle into a calcium chloride aqueous solution with a mass-volume ratio of 1% to form spherical sodium alginate-bentonite gel particles. Filter out the gel particles and wash them with deionized water to remove the residual calcium chloride.

[0067] (3) Filter out the spherical sodium alginate-bentonite gel particles, place the filtered particles on filter paper to remove the remaining moisture on the particle surface, and transfer them to a mold for molding by pressing. Close packing occurs with surface-to-surface contact. Inject the bentonite slurry with a mass-volume ratio of 15% prepared in step (1) into the particle packing mold to immerse the particles, and then soak them in a calcium chloride aqueous solution with a mass-volume ratio of 1% for gel solidification. Take out the gel solid and wash it with deionized water to remove the residual calcium chloride, and further dry it at 40 °C to obtain a porous material green body.

[0068] (4) The obtained green body is calcined at 500 °C for 1 hour to thermally remove the organic matter, and then the temperature is raised to sinter at 1100 °C for 2 hours, and the temperature is decreased with the furnace to obtain a scaffold structure without voids. The solid diagram of the scaffold is as shown in Figure 3 as shown in Figure 3 a. It can be seen from a that the obvious bentonite particles are in the pore structure of the bentonite scaffold, but the combination between the two is tight, and the bentonite particles fill the pore space, resulting in the absence of a porous structure.

[0069] Comparative Example 2: Preparation of diatomite-hydroxyapatite composite scaffold

[0070] (1) Preparation of ceramic slurry: Take 10 g of diatomite powder and add deionized water to 100 mL. Under stirring, add 1.0 g of sodium alginate. After complete dissolution and uniform mixing, a diatomite slurry with a mass-volume ratio of 10% is obtained. In the same process, the above 10 g of diatomite powder is replaced with 20 g of hydroxyapatite to prepare a hydroxyapatite slurry with a mass-volume ratio of 20%.

[0071] (2) Take the diatomite slurry with a mass-volume ratio of 10%. At room temperature, droplets are freely dropped one by one through a 20 ml syringe needle into a calcium chloride aqueous solution with a mass-volume ratio of 1% to form spherical sodium alginate-diatomite gel particles. The gel particles are filtered out and washed with deionized water to remove the residual calcium chloride.

[0072] (3) Filter out the spherical sodium alginate-diatomite gel particles, place the filtered particles on filter paper to remove the remaining moisture on the particle surface, and transfer them to a mold for molding by pressing. Close packing occurs with surface-to-surface contact. Inject the hydroxyapatite slurry with a mass-volume ratio of 20% prepared in step (1) into the particle packing mold to immerse the particles, and then soak them in a calcium chloride aqueous solution with a mass-volume ratio of 1% for gel solidification. Take out the gel solidified body and wash it with deionized water to remove the residual calcium chloride, and further dry it at 40 °C to obtain a green body of porous material.

[0073] (4) The obtained green body is calcined at 500 °C for 1 hour to thermally remove the organic matter, and then the temperature is raised to sinter at 1100 °C for 2 hours, and the temperature is decreased with the furnace to obtain a scaffold structure without voids. The solid diagram of the scaffold is as shown in Figure 3 as shown in Figure 3 b. It can be seen from b that the internal structure of the hydroxyapatite scaffold is completely filled with diatomite particles and there is no macroscopic porous structure.

[0074] Comparative Example 3: Preparation of hydroxyapatite-bentonite composite scaffold

[0075] (1) Preparation of ceramic slurry: Take 10 g of hydroxyapatite powder and add deionized water to make up 100 mL. While stirring, add 1.0 g of sodium alginate. After complete dissolution and thorough mixing, a hydroxyapatite slurry with a mass-to-volume ratio of 10% is obtained. In the same process, replace the above 10 g of hydroxyapatite powder with 10 g of bentonite powder to prepare a bentonite slurry with a mass-to-volume ratio of 10%.

[0076] (2) Take the hydroxyapatite slurry with a mass-to-volume ratio of 10%. At room temperature, form droplets by dripping freely through a 20 mL syringe needle into a 1% calcium chloride aqueous solution to form spherical sodium alginate-hydroxyapatite gel particles. Filter out the gel particles and wash them with deionized water to remove the residual calcium chloride.

[0077] (3) Filter out the spherical sodium alginate-hydroxyapatite gel particles, place the filtered particles on filter paper to remove the remaining moisture on the particle surface, and transfer them to a mold for molding by pressing. Close packing occurs with surface-to-surface contact. Inject the 10% (mass-to-volume) bentonite slurry prepared in step (1) into the particle packing mold to immerse the particles, then soak them in a 1% calcium chloride aqueous solution for gel solidification. Take out the gel solid and wash it with deionized water to remove the residual calcium chloride, and further dry it at 40 °C to obtain a porous material green body.

[0078] (4) The obtained green body is calcined at 500 °C for 1 hour to thermally remove the organic matter, and then the temperature is raised and sintered at 1100 °C for 2 hours, and the furnace is cooled to obtain the scaffold material. The solid diagram of this scaffold is as shown in Figure 3 Figure c, and it can be seen from Figure 3 Figure c that the bentonite scaffold wraps the white hydroxyapatite particles, and the two are tightly combined without obvious macroscopic pore structure.

[0079] Comparative Example 4. Preparation of Porous Hydroxyapatite Scaffold

[0080] (1) Preparation of ceramic slurry: Take 15 g of hydroxyapatite powder and add deionized water to make up 100 mL. While stirring, add 1.0 g of sodium alginate. After complete dissolution and thorough mixing, a hydroxyapatite slurry with a mass-to-volume ratio of 15% is obtained.

[0081] (2) Take a 2% (mass-to-volume) sodium alginate aqueous solution. At room temperature, form droplets by dripping freely through a 20 mL syringe needle into a 1% calcium chloride aqueous solution to form spherical sodium alginate gel particles. Filter out the gel particles and wash them with deionized water to remove the residual calcium chloride. Then, immerse the spherical sodium alginate gel particles in absolute ethanol to displace the internal moisture to obtain sodium alginate solidified particles.

[0082] (3) The ethanol on the surface of the sodium alginate solidified particles is dried with filter paper, and the particles are transferred to a mold for compression molding, and are tightly stacked to form surface-to-surface contact. The hydroxyapatite slurry with a mass volume ratio of 15% prepared in step (1) is injected into the particle stacking mold to immerse the particles, and then immersed in a calcium chloride aqueous solution with a mass volume ratio of 1% to gel solidify, and the gel solid is taken out and washed with deionized water to remove residual calcium chloride, and further dried at 40°C to obtain a nested porous material blank.

[0083] (4) The obtained blank was calcined at 500°C for 1 hour to remove organic matter by pyrolysis, and then the temperature was raised to 1100°C for sintering for 2 hours. The temperature was lowered as the furnace cooled to obtain a porous hydroxyapatite scaffold (the sodium alginate gel particles inside the scaffold were completely degraded after high temperature). The physical diagram of the scaffold is shown in FIG. Figure 3 d, as shown by Figure 3 d It can be seen that the porous hydroxyapatite scaffold has a good spherical porous structure, and there are through holes between the porous structures, and the overall scaffold has good connectivity. However, the scaffold does not have a nested porous structure.

[0084] The beneficial effects of the present invention are demonstrated below through specific test examples.

[0085] Test Example 1: Porous Scaffold State and Porosity Measurement

[0086] The stability of the nested porous stents of Examples 1 to 3 and Comparative Examples 1 to 4 was determined by repeated oscillation method. Each group of stents was fixed in the middle of a centrifuge tube, and then the centrifuge tube was fixed in a three-dimensional rotating mixer, and different modes such as rotation and flipping were set. After 30 minutes, the falling off of the embedded particles in the stent in the centrifuge tube was observed. The results showed that the particles in each group of nested porous stents in Preparation Examples 1 to 3 did not fall off, and they were all stable in the porous stent pore structure, and the particles could move freely with the movement of the stent; the particles in each group of nested stents in Comparative Examples 1 to 3 did not fall off, but the nested particles were directly and tightly combined with the external stent material and could not move, which hindered the pore through-structure; there were no nested particles in the stent of Comparative Example 4.

[0087] The porosity of each group of stents was determined by the water displacement method. The stents of each group of Examples 1 to 3 and Comparative Examples 1 to 4 were taken respectively, and the diameter and height of the stents were measured to calculate the total volume V of the stents. 总 Use a measuring cylinder to measure a certain volume of anhydrous ethanol, immerse the selected stent sample in the anhydrous ethanol, and vacuum degas to allow the ethanol to enter the micropores of the stent. Read the volume of the ethanol liquid level in the measuring cylinder, which is the stent volume V. 支架 . Thus, the scaffold porosity (%) is calculated as (V 总 —V 支架 ) / V 总×100%. The measurement results are shown in Table 1, and the results indicate that: there are no particles filling the internal pores of the hydroxyapatite porous scaffold prepared in Comparative Example 4, and the porosity is the largest; there are particles filling the internal pores of the nested porous scaffolds prepared in Examples 1-3, and the porosity of the scaffolds decreases; while the internal particles of the scaffolds prepared in Comparative Examples 1-3 completely fill the pore structure, causing the macropore structure to disappear and only a small amount of micropore structure remains, so the porosity decreases significantly.

[0088] Table 1. Test results of porosity and permeability of different scaffolds

[0089]

[0090] Experimental Example 2. Determination of the permeability of the porous scaffold

[0091] The liquid penetration method was used to measure the permeability of the scaffolds in each group. Scaffolds in each group of Examples 1-3 and Comparative Examples 1-4 with the same size were taken and assembled in an elastic plastic tube. The outer wall of the scaffold was tightly combined with the plastic tube to ensure that the liquid flowed through the pores of the scaffold. The plastic tube assembled with the scaffold was assembled in the pipeline. One end of the pipeline was connected to the bottom end of an open container, and the other end was suspended above the measuring cylinder. The pipeline was placed horizontally, and the open container was fixed on a shelf at a certain height, and a certain volume of water was added to the container. The volume of water flowing through the pipeline in 10 minutes was collected. The results are shown in Table 1. The results show that for the scaffolds in Comparative Examples 1-3, due to the lack of macropore structure, water slowly penetrated through the micropore structure under static pressure and flowed through the scaffold, and only a small amount of permeate was in the pipeline, and the amount of liquid collected was negligible; the porous hydroxyapatite scaffold in Comparative Example 4 had a large number of macropore structures, and the liquid flowed through the scaffold quickly, and the amount of liquid collected per unit time was the largest; while for the porous scaffolds with nested structures (Examples 1-3), the internal nested particles did not hinder the connectivity of the internal pores of the scaffold, and the solution could pass through the inside of the scaffold smoothly, and the nested particles further dispersed the liquid flowing through the pores and made it flow along the wall surface, and the amount of liquid passing through per unit time decreased (see the schematic diagram in Figure 4 ). When the sewage water body passed through the porous hydroxyapatite scaffold in Comparative Example 4, the water body entered the porous structure and flowed through the through-holes. The water flow velocity at the through-holes was fast, while the water flow velocity on the porous wall surface of the scaffold was low, resulting in the direct flow of the sewage from the through-structure and being unable to fully contact the surface of the scaffold, making it difficult to remove pollutants. Compared with the porous hydroxyapatite scaffold in Comparative Example 4, when the polluted water body passed through the nested scaffold (Examples 1-3), the fluid was redispersed by the embedded particles after entering the porous structure, making the fluid distribution more uniform and contacting the wall surface of the porous scaffold and the surface of the embedded particles, which could improve the adsorption effect of the material on the pollutants in the water body. By adjusting the types of materials of the porous scaffold and the embedded particles, the functions of different materials could be fully exerted to meet various adsorption requirements; by changing the concentrations of the two ceramic slurries in the preparation process, the pore structure size of the prepared nested scaffold and the size of the nested particles could be adjusted to meet different treatment requirements.

[0092] In summary, the present invention provides a nested porous scaffold material. In the pore structure of the porous scaffold material, a particulate structural material that does not hinder the penetration of pores is embedded, enabling the liquid to improve the effective contact with the material wall when passing through the interior of the porous scaffold material, enhancing the mass transfer between the material and the fluid, and being more conducive to the adsorption of heavy metal ions, organic dyes, etc. The porous scaffold material of the present invention can select different materials to meet different usage requirements. At the same time, the process of the porous scaffold material is simple and easy for industrial production. Therefore, the porous scaffold material of the present invention has good application prospects in the fields of sewage treatment and the like.

Claims

1. A method for preparing a nested porous scaffold material, characterized in that: It includes the following steps: (1) adding ceramic powder A and ceramic powder B to an alginate aqueous solution respectively, and dispersing them uniformly to obtain ceramic slurry A and ceramic slurry B; (2) dropping ceramic slurry A into a calcium ion aqueous solution to cross-link and form spherical ceramic particles; (3) piling the spherical ceramic particles obtained in step (2) in a mold, injecting the ceramic slurry B in step (1) into the mold to immerse the ceramic particles, and then transferring the entire slurry into a calcium ion aqueous solution for cross-linking and forming, and obtaining a preform after drying; (4) calcining and sintering the preform obtained in step (3) to obtain a product.

2. The preparation method according to claim 1, characterized in that: In step (1), the concentration of the alginate aqueous solution is 1 to 2 wt %; And / or, in step (1), ceramic powder A and ceramic powder B are the same or different ceramic materials, and the obtained ceramic slurry A has a lower concentration than ceramic slurry B; Preferably, In step (1), the ceramic powder A and the ceramic powder B are independently selected from one or more powders of hydroxyapatite, diatomaceous earth, bentonite, and kaolin; And / or, in step (1), the concentration of the ceramic slurry A and the ceramic slurry B is 5 to 40 wt %.

3. The preparation method according to claim 2, characterized in that: The ceramic powder A is hydroxyapatite, and the ceramic powder B is hydroxyapatite; Alternatively, the ceramic powder A is bentonite, and the ceramic powder B is diatomaceous earth; Alternatively, the ceramic powder A is bentonite, and the ceramic powder B is hydroxyapatite.

4. The preparation method according to claim 3, characterized in that: The ceramic powder A is hydroxyapatite, and the concentration of the ceramic slurry A is 5wt%; the ceramic powder B is hydroxyapatite, and the concentration of the ceramic slurry B is 15wt%; Alternatively, the ceramic powder A is bentonite, the concentration of the ceramic slurry A is 7wt%, the ceramic powder B is diatomaceous earth, and the concentration of the ceramic slurry B is 20wt%; Alternatively, the ceramic powder A is bentonite, the concentration of the ceramic slurry A is 5wt%, the ceramic powder B is hydroxyapatite, the concentration of the ceramic slurry B is 15wt%.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The particle size of the ceramic powder A and the ceramic powder B is ≤10 μm.

6. The preparation method according to claim 1, characterized in that: In step (2) and step (3), the calcium ion aqueous solution is obtained by dissolving calcium chloride or calcium nitrate in water, and the concentration of calcium ions is 0.5 to 2 wt%, preferably 1 wt%.

7. The preparation method according to claim 1, characterized in that: In step (3), the spherical ceramic particles are pressed into shape when they are piled up in a mold so that the particles are in surface contact with each other; And / or, in step (3), the drying temperature is 40 to 100° C.; And / or, in step (4), the calcination temperature is 500-600° C., and / or, the calcination time is 1-10 h; And / or, in step (4), the sintering temperature is 800-1200° C., and / or, the sintering time is 2-3 hours.

8. A nested porous scaffold material, characterized in that: The invention is prepared by the preparation method described in any one of claims 1 to 7.

9. The nested porous scaffold material according to claim 8, characterized in that: The pore structure of the nested porous scaffold material has small ceramic particles embedded therein, which do not hinder the inter-pore structure and do not fall off from the porous structure.

10. Use of the nested porous scaffold material according to claim 8 or 9 in sewage treatment; Preferably, the nested porous scaffold material is used for adsorbing heavy metal ions and organic dyes in a solution.

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