Porous magnesium-calcium composite ceramic prepared by combining 3D printing with biological induction mineralization deposition technology as well as preparation method and application of porous magnesium-calcium composite ceramic

Abstract

The invention discloses a porous magnesium-calcium composite ceramic with 3D printing combined with a biological induction mineralization deposition technology and a preparation method and application thereof, and the porous magnesium-calcium composite ceramic is obtained by microbial induction mineral deposition of a gel-state porous scaffold in a salt solution. Compared with the prior art, the light-weight and high-strength porous ceramic can be prepared in a manner of lower energy consumption and simple operation.

Description

Technical Field

[0001] The present invention belongs to the technical field of porous ceramic manufacturing, and specifically relates to a porous magnesium-calcium composite ceramic combined with 3D printing and bio-induced mineralization deposition technology, and a preparation method and application thereof. Background Art

[0002] Porous ceramics have the characteristics of high specific surface area, good thermal stability, wear resistance and low density. They are suitable for the filtration and separation of gas and liquid media. They are also used in the manufacture of sound-absorbing materials, thermal insulation materials, biomedical engineering materials, ecological restoration materials and new energy materials.

[0003] At present, the preparation process of porous ceramics is inevitably accompanied by high energy consumption. In addition, the use of special powders and chemicals mostly involves complex manufacturing processes. So far, people have developed advanced technologies such as cold sintering, laser sintering, and hot isostatic pressing sintering for the preparation of porous ceramics. These technologies can significantly reduce energy consumption while ensuring the excellent performance of ceramic materials. For example, the hydrothermal-hot isostatic pressing process prepares porous ceramics by volatilization of water vapor. The porous ceramic materials obtained have high compressive strength, stable performance, and a wide range of pore size distribution. The sol-gel process still needs to be combined with a hot sintering method to prepare materials with specific pore structures. 3D printing technology has a high degree of manufacturing flexibility and can produce high-strength porous ceramics with specific shapes, sizes, and pore structures. However, the existing 3D printing technology still needs to be combined with hot sintering technology to prepare porous ceramics with light weight and high strength.

[0004] In summary, porous ceramic materials have problems such as high energy consumption in the preparation process, complicated process and few functions of the porous ceramic materials obtained, and there is still room for improvement. Summary of the invention

[0005] The present invention aims to provide a porous magnesium-calcium composite ceramic combined with 3D printing and microbial mineralization technology and its preparation method and application. The porous magnesium-calcium composite ceramic is prepared by 3D printing of foam bio-ink to obtain a porous scaffold, and then obtained by biologically induced mineralization deposition in a salt solution. The raw materials are economical and environmentally friendly, the preparation method is efficient and low-consumption, and the prepared porous magnesium-calcium composite ceramic has high mechanical strength.

[0006] The technical solution of the present invention is as follows:

[0007] A porous magnesium-calcium composite ceramic that combines 3D printing with bio-induced mineralization deposition technology, which is obtained by microbially induced mineral deposition of a porous scaffold in a gel state in a salt solution;

[0008] The porous scaffold is obtained by 3D printing of foam bio-ink, which includes the following components by weight: 0.9-4.5 parts of biomass macromolecules, 10-100 parts of nanoparticles, 0.1-1 parts of surfactants, 5-20 parts of bacterial liquid and appropriate amount of water;

[0009] The biomass macromolecule is at least one of sodium alginate, gelatin, polyvinyl alcohol, and xanthan gum;

[0010] The nanoparticles are at least one of silicon dioxide, montmorillonite, laponite, bentonite, calcium carbonate and hydroxyapatite; the particle size of the nanoparticles ranges from 20 to 2000 nm, and the contact angle with deionized water is 110° to 150°.

[0011] The bacterial solution is a culture solution of at least one of Bacillus, Escherichia coli and Corynebacterium;

[0012] In some preferred implementations, the microbial induced mineral deposition is carbonate deposition, and the salt solution is a mixed solution of urea, magnesium salt and calcium salt, wherein the concentration of urea is 0.02-2 mol / L, the concentration of calcium ions is 0.02-2 mol / L, and the molar ratio of magnesium ions to calcium ions is 0-5:1.

[0013] More preferably, the magnesium salt is at least one of magnesium sulfate, magnesium chloride and magnesium nitrate, and the calcium salt is at least one of calcium chloride, calcium nitrate and calcium lactate.

[0014] In some preferred implementations, the microbial induced mineral deposition is phosphate deposition, and the salt solution is a mixed solution of urea, magnesium salt and phosphate, wherein the concentration of urea is 0.02-2 mol / L, the concentration of magnesium ions is 0.01-2 mol / L, and the molar ratio of magnesium ions to phosphate ions is 0.2-10:1.

[0015] More preferably, the magnesium salt is at least one of magnesium sulfate, magnesium chloride and magnesium nitrate, and the phosphate is at least one of sodium dihydrogen phosphate, potassium dihydrogen phosphate and potassium dihydrogen phosphate.

[0016] In some preferred implementations, the biomass macromolecules and water are mixed to obtain an aqueous solution of the biomass macromolecules, wherein the concentration of the biomass macromolecules is 0.1-5 wt %.

[0017] In some preferred implementations, the surfactant is at least one of dimethyl distearyl ammonium chloride, dimethyl stearamine, benzalkonium chloride, ammonium laureth sulfate, sodium dodecylbenzene sulfonate, dioctyl sodium sulfosuccinate, lauryl alcohol polyoxyethylene ether, nonylphenol polyoxyethylene ether, lauryl glucoside and polyethylene glycol.

[0018] A method for preparing the porous magnesium-calcium composite ceramic comprises the following steps:

[0019] (1) preparing an aqueous solution of biomass macromolecules, and then dispersing nanoparticles and a surfactant in the aqueous solution of biomass macromolecules to obtain a particle slurry;

[0020] (2) mixing the bacterial liquid and the particle slurry evenly to obtain a particle / microorganism slurry;

[0021] (3) stirring and foaming the particle / microorganism slurry to obtain foam bio-ink;

[0022] (4) 3D printing using foam bio-ink to obtain a porous scaffold;

[0023] (5) placing the porous scaffold in a salt solution and leaving it to stand for 1-7 days to obtain a porous magnesium-calcium composite ceramic.

[0024] In some preferred implementations, the nozzle diameter of 3D printing is 0.4-3 mm, and the extrusion speed of 3D printing is 1-300 mm / s.

[0025] In some preferred implementations, the rotation speed of stirring and foaming is 500-5000 rpm, and the time of stirring and foaming is 3-20 min.

[0026] The above-mentioned porous magnesium-calcium composite ceramics are used in engineering materials, marine ecological restoration, cultural relic restoration, acidic soil improvement and removal of heavy metal ions in water bodies.

[0027] The present invention has at least the following beneficial effects:

[0028] The present invention integrates bio-induced mineralization deposition technology and bio-3D printing technology. The bacterial liquid, nanoparticles, surfactants and biomass macromolecules are mechanically foamed to obtain a high modulus, Pickering foam structure and easy-to-process foam bio-ink. Afterwards, a gel-state porous scaffold is obtained by 3D printing of the foam bio-ink and hardened in a salt solution by bio-induced mineralization deposition.

[0029] The above raw materials are economical and environmentally friendly. The biomass macromolecules can fix the microorganisms in the bacterial liquid, increase the concentration of microorganisms in the biological foam ink, and are beneficial to the transportation of nutrients required for the microorganisms to maintain metabolism; the nanoparticles are Pickering stabilizers, which make the foam in the prepared foam biological ink have excellent stability, improve the viscoelastic properties of the ink, and achieve the effect of thickening the ink.

[0030] 3D printing technology has a high degree of manufacturing flexibility and can produce products with specific shapes and sizes. Combining it with bio-induced mineralization deposition technology can produce lightweight and high-strength porous ceramics in a way that consumes less energy and is simpler to operate than thermal sintering technology.

[0031] The above components and preparation methods cooperate with each other, so that the porous magnesium-calcium composite ceramics have the advantages of good loading capacity, environmental friendliness, high stability, multi-function and simple preparation. It can be used in engineering materials, marine ecological restoration, cultural relics restoration, acidic soil improvement and removal of heavy metal ions in water bodies. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is an optical microscope image of the foam bio-ink prepared in Example 1;

[0033] Figure 2 This is a scanning electron microscope image of the porous magnesium-calcium composite ceramic prepared in Example 1;

[0034] Figure 3 This is a photo of the porous magnesium-calcium composite ceramic prepared in Example 1;

[0035] Figure 4 The compressive stress-strain curve of the porous magnesium-calcium composite ceramic prepared in Example 1;

[0036] Figure 5 The following are photos of an example of using the porous magnesium-calcium composite ceramics prepared in Example 1 for coral restoration, wherein (a) is a photo of the porous magnesium-calcium composite ceramics after grafting coral branches on the surface, and (b) is a photo of (a) after it has been placed for 38 days. DETAILED DESCRIPTION

[0037] The technical solution of the present invention is further illustrated and described below through specific implementation methods.

[0038] In the following examples, the water used can be one or more of distilled water, purified water, and drinking water; unless otherwise specified, the detection methods in the following examples are conventional detection methods; the reagents in the following examples are purchased from commercial channels unless otherwise specified.

[0039] This application does not specify the concentration of the microorganisms in the bacterial solution, as long as the foam bio-ink contains the microorganisms.

[0040] The microorganism used in this experiment is Bacillus pasteurii (Sporosarcina pasteurii, also known as Bacillus pasteurii), in the form of freeze-dried powder of the strain, purchased from the American Type Culture Collection (ATCC), with the number ATCC 11859.

[0041] Example 1

[0042] (1) A 0.1 wt % aqueous solution of sodium alginate was prepared, and 10 parts of laponite particles, 5 parts of calcium carbonate particles and 0.1 parts of a surfactant (dimethyl distearyl ammonium chloride) were dispersed in 90 parts of the aqueous solution of sodium alginate to obtain a particle slurry.

[0043] (2) The bacterial liquid of Bacillus pasteurianus and the particle slurry are mixed evenly to obtain a particle / microorganism slurry.

[0044] (3) Then, stirring and foaming is performed at a speed of 500-2000 rpm for 3-6 min to obtain Figure 1 The foam bio-ink shown, it can be seen that the foam bio-ink is filled with tiny bubbles.

[0045] (4) Using a 3D printing device to print the foam bio-ink into a porous scaffold, wherein the printing parameters of the 3D printing device are: a nozzle diameter of 0.4 mm and an extrusion speed of 1 mm / s.

[0046] (5) The scaffold was placed in a mixed solution with a urea concentration of 0.02 mol / L and a calcium chloride concentration of 0.02 mol / L for carbonate precipitation and reacted for 2 days to obtain the following Figure 2 and Figure 3 The porous magnesium-calcium composite ceramic shown has the advantages of high porosity and large specific surface area.

[0047] Example 2

[0048] (1) A 0.1 wt % aqueous solution of sodium alginate was prepared, and 70 parts of laponite particles, 30 parts of montmorillonite particles and 1 part of a surfactant (dimethyl stearylamine) were dispersed in 90 parts of the aqueous solution of sodium alginate to obtain a particle slurry.

[0049] (2) The bacterial liquid of Bacillus pasteurianus and the particle slurry are mixed evenly to obtain a particle / microorganism slurry.

[0050] (3) Then, the mixture was stirred and foamed at a rotation speed of 5000 rpm for 20 min to obtain foam bio-ink.

[0051] (4) Using a 3D printing device to print the foam bio-ink into a porous scaffold, wherein the printing parameters of the 3D printing device are: a nozzle diameter of 3 mm and an extrusion speed of 300 mm / s.

[0052] (5) The scaffold was placed in a mixed solution with a urea concentration of 2 mol / L, a calcium chloride concentration of 2 mol / L, and a magnesium sulfate concentration of 10 mol / L for carbonate deposition. The reaction lasted for 7 days to obtain a porous magnesium-calcium composite ceramic.

[0053] Example 3

[0054] (1) A 0.1 wt% aqueous solution of polyvinyl alcohol was prepared, and 20 parts of silica particles, 30 parts of montmorillonite particles and 0.2 parts of a surfactant (benzalkonium chloride) were dispersed in 90 parts of the aqueous solution of polyvinyl alcohol to obtain a particle slurry.

[0055] (2) The bacterial liquid of Bacillus pasteurianus and the particle slurry are mixed evenly to obtain a particle / microorganism slurry.

[0056] (3) Then, the mixture was stirred and foamed at a rotation speed of 2000 rpm for 10 min to obtain foam bio-ink.

[0057] (4) Using a 3D printing device to print the foam bio-ink into a porous scaffold, wherein the printing parameters of the 3D printing device are: a nozzle diameter of 1 mm and an extrusion speed of 100 mm / s.

[0058] (5) The scaffold was placed in a mixed solution of 1 mol / L urea, 1 mol / L calcium nitrate, and 1 mol / L magnesium nitrate for carbonate deposition and reacted for 3 days to obtain a porous magnesium-calcium composite ceramic.

[0059] Example 4

[0060] (1) A 5 wt % gelatin aqueous solution was prepared, and 30 parts of calcium carbonate particles, 10 parts of montmorillonite particles, 10 parts of bentonite particles and 0.5 parts of a surfactant (ammonium lauryl polyether sulfate) were dispersed in 90 parts of the gelatin aqueous solution to obtain a particle slurry.

[0061] (2) The bacterial liquid of Bacillus pasteurianus and the particle slurry are mixed evenly to obtain a particle / microorganism slurry.

[0062] (3) Then, the mixture was stirred and foamed at a rotation speed of 1000 rpm for 15 min to obtain foam bio-ink.

[0063] (4) Using a 3D printing device to print the foam bio-ink into a porous scaffold, wherein the printing parameters of the 3D printing device are: a nozzle diameter of 0.8 mm and an extrusion speed of 100 mm / s.

[0064] (5) The scaffold was placed in a mixed solution of 0.5 mol / L urea, 0.5 mol / L calcium lactate, and 1.5 mol / L magnesium chloride for carbonate deposition. The reaction lasted for 5 days to obtain a porous magnesium-calcium composite ceramic.

[0065] Example 5

[0066] (1) A 2 wt % aqueous solution of xanthan gum was prepared, and 20 parts of hydroxyapatite particles, 10 parts of montmorillonite particles and 0.3 parts of a surfactant (sodium dodecylbenzene sulfonate) were dispersed in 90 parts of the aqueous solution of xanthan gum to obtain a particle slurry.

[0067] (2) The bacterial liquid of Bacillus pasteurianus and the particle slurry are mixed evenly to obtain a particle / microorganism slurry.

[0068] (3) Then, the mixture was stirred and foamed at a rotation speed of 800 rpm for 10 min to obtain foam bio-ink.

[0069] (4) Using a 3D printing device to print the foam bio-ink into a porous scaffold, wherein the printing parameters of the 3D printing device are: a nozzle diameter of 2 mm and an extrusion speed of 120 mm / s.

[0070] (5) The scaffold was placed in a mixed solution of 0.1 mol / L urea, 0.1 mol / L calcium chloride, and 0.3 mol / L magnesium sulfate for carbonate deposition and reacted for 2 days to obtain a porous magnesium-calcium composite ceramic.

[0071] Example 6

[0072] (1) A 1 wt % aqueous solution of sodium alginate was prepared, and 50 parts of silicon dioxide particles and 0.6 parts of a surfactant (sodium dioctyl sulfosuccinate) were dispersed in 90 parts of the aqueous solution of sodium alginate to obtain a particle slurry.

[0073] (2) The bacterial liquid of Bacillus pasteurianus and the particle slurry are mixed evenly to obtain a particle / microorganism slurry.

[0074] (3) Then, the mixture was stirred and foamed at a rotation speed of 1200 rpm for 8 min to obtain foam bio-ink.

[0075] (4) Using a 3D printing device to print the foam bio-ink into a porous scaffold, wherein the printing parameters of the 3D printing device are: a nozzle diameter of 0.6 mm and an extrusion speed of 200 mm / s.

[0076] (5) The scaffold was placed in a mixed solution of 0.2 mol / L urea, 0.01 mol / L magnesium sulfate, and 0.05 mol / L potassium dihydrogen phosphate for phosphate deposition and reacted for 3 days to obtain a porous magnesium-calcium composite ceramic.

[0077] Example 7

[0078] (1) A 1.5 wt % polyvinyl alcohol aqueous solution was prepared, and 60 parts of calcium carbonate particles, 15 parts of laponite particles and 0.2 parts of a surfactant (lauryl polyoxyethylene ether) were dispersed in 90 parts of the polyvinyl alcohol aqueous solution to obtain a particle slurry.

[0079] (2) The bacterial liquid of Bacillus pasteurianus and the particle slurry are mixed evenly to obtain a particle / microorganism slurry.

[0080] (3) Then, the mixture was stirred and foamed at a rotation speed of 750 rpm for 17 min to obtain foam bio-ink.

[0081] (4) Using a 3D printing device to print the foam bio-ink into a porous scaffold, wherein the printing parameters of the 3D printing device are: a nozzle diameter of 1.5 mm and an extrusion speed of 300 mm / s.

[0082] (5) The scaffold was placed in a mixed solution of 0.5 mol / L urea, 0.01 mol / L magnesium sulfate, and 0.05 mol / L potassium dihydrogen phosphate for phosphate deposition and reacted for 3 days to obtain a porous magnesium-calcium composite ceramic.

[0083] Example 8

[0084] (1) A 2.5 wt% aqueous solution of xanthan gum was prepared, and 45 parts of laponite particles, 25 parts of bentonite particles and 0.7 parts of a surfactant (nonylphenol polyoxyethylene ether) were dispersed in 90 parts of the aqueous solution of xanthan gum to obtain a particle slurry.

[0085] (2) The bacterial liquid of Bacillus pasteurianus and the particle slurry are mixed evenly to obtain a particle / microorganism slurry.

[0086] (3) Then, the mixture was stirred and foamed at a rotation speed of 1750 rpm for 8 min to obtain foam bio-ink.

[0087] (4) Using a 3D printing device to print the foam bio-ink into a porous scaffold, wherein the printing parameters of the 3D printing device are: a nozzle diameter of 0.65 mm and an extrusion speed of 260 mm / s.

[0088] (5) The scaffold was placed in a mixed solution with a urea concentration of 1 mol / L, a magnesium chloride concentration of 2 mol / L, and a potassium dihydrogen phosphate concentration of 0.5 mol / L for phosphate deposition. The reaction lasted for 5 days to obtain a porous magnesium-calcium composite ceramic.

[0089] Example 9

[0090] (1) A 3 wt % gelatin aqueous solution was prepared, and 30 parts of hydroxyapatite particles, 30 parts of bentonite particles and 0.5 parts of a surfactant (lauryl glucoside) were dispersed in 90 parts of the gelatin aqueous solution to obtain a particle slurry.

[0091] (2) The bacterial liquid of Bacillus pasteurianus and the particle slurry are mixed evenly to obtain a particle / microorganism slurry.

[0092] (3) Then, the mixture was stirred and foamed at a rotation speed of 1100 rpm for 18 min to obtain foam bio-ink.

[0093] (4) Using a 3D printing device to print the foam bio-ink into a porous scaffold, wherein the printing parameters of the 3D printing device are: a nozzle diameter of 1.3 mm and an extrusion speed of 140 mm / s.

[0094] (5) The scaffold was placed in a mixed solution of 0.1 mol / L urea, 0.1 mol / L magnesium nitrate, and 0.1 mol / L potassium dihydrogen phosphate for phosphate deposition and reacted for 2 days to obtain a porous magnesium-calcium composite ceramic.

[0095] Example 10

[0096] (1) A 0.5 wt % aqueous solution of sodium alginate was prepared, and 60 parts of silicon dioxide particles, 10 parts of montmorillonite particles and 0.5 parts of a surfactant (polyethylene glycol) were dispersed in 90 parts of the aqueous solution of sodium alginate to obtain a particle slurry.

[0097] (2) The bacterial liquid of Bacillus pasteurianus and the particle slurry are mixed evenly to obtain a particle / microorganism slurry.

[0098] (3) Then, the mixture was stirred and foamed at a rotation speed of 1300 rpm for 7 min to obtain foam bio-ink.

[0099] (4) Using a 3D printing device to print the foam bio-ink into a porous scaffold, wherein the printing parameters of the 3D printing device are: a nozzle diameter of 3 mm and an extrusion speed of 100 mm / s.

[0100] (5) The scaffold was placed in a mixed solution of 2 mol / L urea, 0.05 mol / L magnesium nitrate, and 0.01 mol / L potassium dihydrogen phosphate for phosphate deposition and reacted for 7 days to obtain a porous magnesium-calcium composite ceramic.

[0101] Example 11 Performance Test

[0102] The porous magnesium-calcium composite ceramics prepared in Example 1 were used as an example to carry out compression tests and coral restoration tests.

[0103] Among them, the compressive stress-strain curve of porous magnesium-calcium composite ceramics is as follows: Figure 4 As shown, it can be seen that the porous magnesium-calcium composite ceramic has good compressive strength (10.3MPa).

[0104] like Figure 5 As shown in (a), the surface of the porous magnesium-calcium composite ceramic prepared in Example 1 was grafted with coral branches and then placed in a reef salt simulation test tank. After a period of time, Figure 5 As shown in (b), it can be observed that the coral branches grow and begin to wrap the living porous ceramic downwards, indicating that the coral branches can grow on the surface of the porous magnesium-calcium composite ceramic, and the porous magnesium-calcium composite ceramic prepared in Example 1 can be used in the field of coral restoration.

[0105] The above description is only a preferred embodiment of the present invention, and therefore cannot be used to limit the scope of the present invention. That is, equivalent changes and modifications made according to the patent scope of the present invention and the contents of the specification should still fall within the scope of the present invention.

Claims

1. A porous magnesium-calcium composite ceramic using 3D printing combined with bio-induced mineralization deposition technology, characterized in that: It is obtained by microbial-induced mineral deposition in a salt solution through a gel-like porous scaffold; The porous scaffold is obtained by 3D printing of foam bio-ink, and the foam bio-ink includes the following components by weight: 0.9-4.5 parts of biomass macromolecules, 10-100 parts of nanoparticles, 0.1-1 parts of surfactants, 5-20 parts of bacterial liquid and appropriate amount of water; The biomass macromolecule is at least one of sodium alginate, gelatin, polyvinyl alcohol, and xanthan gum; The nanoparticles are at least one of silicon dioxide, montmorillonite, laponite, bentonite, calcium carbonate, and hydroxyapatite; the particle size of the nanoparticles is in the range of 20-2000 nm, and the contact angle with deionized water is 110°-150°; The bacterial liquid is a culture liquid of at least one of bacillus, Escherichia coli and coryneform bacteria.

2. The porous magnesium-calcium composite ceramic according to claim 1, characterized in that: The microbial induced mineral deposition is carbonate deposition, and the salt solution is a mixed solution of urea, magnesium salt and calcium salt, wherein the concentration of the urea is 0.02-2 mol / L, the concentration of the calcium ions is 0.02-2 mol / L, and the molar ratio of the magnesium ions to the calcium ions is 0-5:

1.

3. The porous magnesium-calcium composite ceramic according to claim 2, characterized in that: The magnesium salt is at least one of magnesium sulfate, magnesium chloride and magnesium nitrate, and the calcium salt is at least one of calcium chloride, calcium nitrate and calcium lactate.

4. The porous magnesium-calcium composite ceramic according to claim 1, characterized in that: The microbial induced mineral deposition is phosphate deposition, and the salt solution is a mixed solution of urea, magnesium salt and phosphate, wherein the concentration of the urea is 0.02-2 mol / L, the concentration of the magnesium ion is 0.01-2 mol / L, and the molar ratio of the magnesium ion to the phosphate ion is 0.2-10:

1.

5. The porous magnesium-calcium composite ceramic according to claim 4, characterized in that: The magnesium salt is at least one of magnesium sulfate, magnesium chloride and magnesium nitrate, and the phosphate is at least one of sodium dihydrogen phosphate, potassium dihydrogen phosphate and potassium dihydrogen phosphate.

6. The porous magnesium-calcium composite ceramic according to claim 1, characterized in that: The biomass macromolecules and the water are mixed to obtain an aqueous solution of the biomass macromolecules, wherein the concentration of the biomass macromolecules is 0.1-5wt%.

7. A method for preparing the porous magnesium-calcium composite ceramic according to any one of claims 1 to 6, characterized in that: The steps include: (1) preparing an aqueous solution of biomass macromolecules, and then dispersing nanoparticles and a surfactant in the aqueous solution of biomass macromolecules to obtain a particle slurry; (2) uniformly mixing the bacterial liquid and the particle slurry to obtain a particle / microorganism slurry; (3) stirring and foaming the particle / microorganism slurry to obtain foam bio-ink; (4) using the foam bio-ink to perform 3D printing to obtain a porous scaffold; (5) placing the porous support in a salt solution and leaving it to stand for 1-7 days to obtain a porous magnesium-calcium composite ceramic.

8. The preparation method according to claim 7, characterized in that: The nozzle diameter of the 3D printing is 0.4-3 mm, and the extrusion speed of the 3D printing is 1-300 mm / s.

9. The preparation method according to claim 7, characterized in that: The rotation speed of the stirring and foaming is 500-5000 rpm, and the time of the stirring and foaming is 3-20 min.

10. Application of the porous magnesium-calcium composite ceramics according to any one of claims 1 to 6 in engineering materials, marine ecological restoration, cultural relic restoration, acidic soil improvement and removal of heavy metal ions in water bodies.

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