3D printing of a fully degradable cellulose and lignin composite self-watering water purification core material and preparation method

Abstract

The application discloses a 3D printing full-degradation cellulose and lignin composite self-water-transporting water purification core material and a preparation method thereof, and belongs to the technical field of water purification materials. The composite self-water-transporting water purification core material is of a core-shell structure, the shell layer comprises cellulose, and the core layer comprises cellulose and lignin. The composite self-water-transporting water purification core material provided by the application has more abundant raw material sources, is lower in cost, does not need to be additionally provided with auxiliary devices such as pressure pumps, is basically equal in water filtration capacity to a 100G filter core on the market, and has good metal ion filtration capacity, mechanical strength and antibacterial performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water purification materials, and particularly relates to a 3D-printed full-degradable cellulose and lignin composite self-water-transporting water purification core material and a preparation method. BACKGROUND

[0002] With the emphasis on water quality safety and health, the market of water purifier filter cores is gradually expanding, and the industry scale is also expanding year by year. The water purification filter cores on the market are mainly divided into RO membranes, activated carbon, ceramics and several types, most of which are mainly RO membranes.

[0003] Although the RO membrane of the traditional filter core can remove harmful substances such as heavy metals, bacteria and viruses in water, it belongs to a petroleum-based chemical synthetic material and does not have degradable performance. The post-processing process is complex, and microplastic problems are easy to occur, which has an adverse effect on the environment. In addition, the traditional filter core needs to be additionally equipped with a pressure pump in the reverse osmosis filtration part, which not only occupies a certain internal volume, but also produces additional energy consumption. SUMMARY

[0004] In order to solve the above-mentioned deficiencies existing in the prior art, the purpose of the present application is to provide a 3D-printed full-degradable cellulose and lignin composite self-water-transporting water purification core material and a preparation method, so as to solve the problems that the existing water purification core material is not degradable and needs a pressure pump to produce additional energy consumption.

[0005] The technical scheme for solving the above-mentioned technical problems of the present application is as follows: a 3D-printed full-degradable cellulose and lignin composite self-water-transporting water purification core material is provided, which has a core-shell structure, the shell layer includes cellulose, and the core layer includes cellulose and lignin.

[0006] The composite self-water-transporting water purification core material provided by the present application uses lignin and cellulose as raw materials, which are natural macromolecular materials. The raw materials have a wide source and low cost, and have the advantage of degradability. Lignin has hydrophobicity. Because lignin molecules contain a large number of aromatic ring structures, these structural characteristics make lignin have strong repulsion to water, so lignin has the characteristic of not being easy to absorb water. Cellulose is a polysaccharide polymer with strong hydrophilicity, and its molecules contain a large number of hydroxyl groups, so cellulose has good water absorption. The composite self-water-transporting water purification core material provided by the present application includes cellulose in the shell layer, and the cellulose has water absorption, so water is absorbed into the composite self-water-transporting water purification core material. The core layer contains lignin, which has hydrophobicity, so that water is automatically transported. The lignin alone cannot be formed into a shape, and needs to be combined with cellulose to form a composite self-water-transporting water purification core material with a certain shape.

[0007] On the basis of the above technical scheme, the present application can also be improved as follows:

[0008] Further, the volume ratio of the core layer material and the shell layer material is 1:3-5; preferably, the volume ratio of the core layer material and the shell layer material is 1:3-4.

[0009] The beneficial effect of the above further technical solution is that when the volume ratio of the core layer material and the shell layer material is 1:3-5 during 3D printing, the material can be successfully formed during 3D printing, and the material has a good physical structure and good mechanical properties after drying.

[0010] Further, the mass ratio of cellulose and lignin in the core layer is 1:1-3.

[0011] The beneficial effect of the above further technical solution is that when the mass ratio of cellulose and lignin is controlled to be 1:1-3, good hydrophobic effect can be achieved, water can be self-transported, and a certain shape can be formed. If the content of nanocellulose is too high, the viscosity of the core layer material is large, the water filtration capacity is reduced, and the hydrophilic-hydrophobic interface between lignin and cellulose is loose. If the content of cellulose is too low, the viscosity of the core layer material is too small, which increases the printing difficulty and is not conducive to printing. When the mass ratio of cellulose and lignin is 1:1, the effect is better.

[0012] Further, the morphology of lignin in the core layer is lignin nanotube.

[0013] The beneficial effect of the above further technical solution is that it has been found through verification that lignin with a microstructure of nanotube can be well distributed in nanocellulose, the structure of the core layer material is more stable, and the loss rate of lignin in the core layer is slower during water filtration. In addition, lignin nanotube has good water filtration effect, metal ions in the water sample can contact lignin more fully, and the adsorption capacity of lignin nanotube for metal ions is stronger.

[0014] The preparation method of the above 3D printed full-degradable cellulose and lignin composite self-water-transporting and water-purifying core material includes the following steps:

[0015] (1) Preparation of core layer composite material

[0016] Mix lignin and cellulose, add deionized water, mix uniformly, obtain a mixture, then centrifuge the mixture to remove bubbles, and prepare a core layer composite material;

[0017] (2) Preparation of shell layer material

[0018] Dissolve cellulose in a tetrabutylammonium hydroxide / dimethyl sulfoxide mixed solution, then load it into a needle tube for extrusion, and prepare a shell layer material;

[0019] (3) Preparation of composite self-water-transporting and water-purifying core material

[0020] The core layer composite material and the shell layer material are used to prepare the composite self-water-transporting and water-purifying core material by 3D printing.

[0021] The lignin and cellulose are mixed, deionized water is added, and the mixture is uniformly mixed, so that the lignin and cellulose can be fully dispersed in water, and then the dispersed mixture is centrifuged to remove bubbles, so that the influence of the bubbles on the properties of the subsequent material can be reduced, and the uniformity of the mixture is ensured. In the preparation of the shell layer material, the tetrabutylammonium hydroxide / dimethyl sulfoxide mixed solution is a dissolving agent for cellulose, which helps the dispersion and dissolution of cellulose. In the tetrabutylammonium hydroxide / dimethyl sulfoxide mixed solution, tetrabutylammonium hydroxide (TBAH) can break the hydrogen bonds between cellulose molecules, making it easier to dissolve. Dimethyl sulfoxide (DMSO) helps to promote the interaction between the solvent and cellulose, improving the dissolution efficiency. After the cellulose is dissolved in the above-mentioned mixed solution, it is loaded into a needle tube for extrusion, and a material with a fixed shape can be obtained. Finally, the core layer composite material and the shell layer material are used to prepare the composite self-water-transporting and water-purifying core material by 3D printing. The 3D printing method can meet the complex and personalized customization needs of users, and cater to the future trend of personalization and customization.

[0022] Further, in the mixture of step (1), the total mass of lignin and cellulose accounts for 3-5% of the total mass of the mixture.

[0023] Further, in step (1), the morphology of lignin is lignin nanotube, which is prepared by the following method:

[0024] The lignin is added to water, then a cosolvent is added, and finally an electrolyte is added, and the mixture is mixed and dialyzed to obtain lignin nanotubes; or

[0025] The cosolvent is mixed with water to form a cosolvent aqueous solution, then lignin is added, and finally an electrolyte is added, and the mixture is mixed and dialyzed to obtain lignin nanotubes;

[0026] The electrolyte is any one of sodium chloride, calcium chloride, potassium carbonate, sodium bromide, sodium sulfate, sodium nitrate, copper chloride, copper sulfate, ferrous chloride, ferric chloride, cobalt sulfate, and nickel sulfate;

[0027] When the electrolyte is sodium chloride, calcium chloride, potassium carbonate, sodium bromide, sodium sulfate, sodium nitrate, copper chloride, and ferrous chloride, the concentration of the electrolyte in the reaction system is 0.01-1 mol / L; when the electrolyte is ferric chloride, the concentration of the electrolyte in the reaction system is greater than or equal to 0.01 mol / L and less than 0.05 mol / L;

[0028] The cosolvent is methanol, ethanol, ethylene glycol, tetrahydrofuran, dioxane, or N,N-dimethylformamide.

[0029] Further, the mass concentration of the lignin in the cosolvent aqueous solution is 1-20%.

[0030] Further, the volume concentration of the cosolvent in the reaction system is 10-90% after the cosolvent is added.

[0031] Further, the dialysis temperature is 20-60℃, and the dialysis time is 2-4 days.

[0032] Further, the cellulose is dissolved in the tetrabutylammonium hydroxide / dimethyl sulfoxide mixed solution in step (2) to make the concentration of the cellulose 5-7wt%.

[0033] The beneficial effects of the above further technical solutions are: the content of the cellulose should be controlled to be 5-7wt%, and the content of 6wt% is optimal. When the content of the cellulose is low, such as 5wt%, the viscosity of the shell layer raw material is small, and the material structure cannot be accumulated during printing, so that the material is difficult to be formed. When the content of the cellulose is high, such as 7wt%, the viscosity of the shell layer raw material is large, and it is difficult to extrude from the needle tube using a peristaltic pump, so that the printing cannot be performed.

[0034] Further, the volume ratio of tetrabutylammonium hydroxide and dimethyl sulfoxide in step (2) is 15-25:65-75.

[0035] The present application has the following beneficial effects:

[0036] The composite self-water-transporting water purification core material provided by the present application has a core-shell structure, the shell layer comprises cellulose, the cellulose has water absorption, water is absorbed into the composite self-water-transporting water purification core material, and the core layer comprises lignin, the lignin has hydrophobic properties, so that water is automatically transported. The lignin alone cannot be formed by printing, and the viscosity of the cellulose is needed to cooperate with the lignin, and finally the composite self-water-transporting water purification core material with a certain shape can be formed by 3D printing. The composite self-water-transporting water purification core material provided by the present application has more abundant raw material sources, lower cost, and does not need to be equipped with auxiliary devices such as pressure pumps. The water filtration capacity is basically the same as that of the 100G filter element on the market, and the composite self-water-transporting water purification core material has good metal ion filtration capacity and mechanical strength. When the lignin nanotube is doped with silver and used to prepare the composite self-water-transporting water purification core material, the composite self-water-transporting water purification core material has excellent antibacterial performance. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 It is a transmission electron microscope image of CNF.

[0038] Figure 2 It is an SEM morphology diagram of the core layer composite material.

[0039] Figure 3 It is an infrared spectrum diagram of the core layer composite material.

[0040] Figure 4 SEM morphology of the shell composite material.

[0041] Figure 5 Infrared spectrum of the shell composite material.

[0042] Figure 6 Structural schematic diagram of the composite self-water-transporting water purification core material.

[0043] Figure 7 SEM morphology of the composite self-water-transporting water purification core material.

[0044] Figure 8 Mechanical property test results of the composite self-water-transporting water purification core material.

[0045] Figure 9 Standard curve of Cu ions in the test of the metal ion filtration capacity of the composite self-water-transporting water purification core material.

[0046] Figure 10 Standard curve of Zn ions in the test of the metal ion filtration capacity of the composite self-water-transporting water purification core material.

[0047] Figure 11 Standard curve of Cu ions in the test of the metal ion filtration capacity of the reverse osmosis (RO) membrane and the JIUYANG T07 composite ceramic filter core.

[0048] Figure 12 Standard curve of Zn ions in the test of the metal ion filtration capacity of the reverse osmosis (RO) membrane and the JIUYANG T07 composite ceramic filter core. DETAILED DESCRIPTION

[0049] The following examples are intended to illustrate but not limit the present application. Unless otherwise indicated, the conditions in the examples are conventional or those recommended by the manufacturer. Unless otherwise indicated, the reagents or instruments used are conventional and commercially available.

[0050] Example 1:

[0051] A printing full-degradable cellulose and lignin composite self-water-transporting water purification core material, and a preparation method thereof, includes the following steps:

[0052] (1) Preparation of lignin nanotubes

[0053] To 100 mL of 20% tetrahydrofuran aqueous solution, 2 g of delignified lignin was added, stirred at room temperature for 1 h until completely dissolved, then 0.2925 g of sodium chloride (0.05 M) was added and stirred for 1 h, finally the mixed lignin solution was loaded into a dialysis bag, dialyzed at room temperature for 48 h, the dialysate was divided into beakers, liquid ammonia was frozen, and then vacuum freeze-drying machine was used for freeze-drying to obtain lignin nanotubes (LNT).

[0054] (2) Preparation of core layer lignin nanotube / nanocellulose composite material (LNT / CNF)

[0055] An equal mass of lignin nanotubes and nanocellulose (CNF) was weighed, added to 20 g of deionized water to obtain a mixture, so that the total mass of lignin nanotubes and nanocellulose accounted for 4% of the total mass of the mixture, and the mixture was placed into a planetary mixer for dispersion until uniform (10 min each time, 1500 r / min for the first 5 min and 2000 r / min for the last 5 min). The dispersed mixture was loaded into a syringe, loaded into a centrifuge tube and placed into a centrifuge for debubbling; wherein the parameters during debubbling were: 3 min, 2500 r / min, and finally a core layer lignin nanotube / nanocellulose composite material (LNT / CNF) was prepared.

[0056] The transmission electron microscope image of the CNF is shown in Figure 1 As can be seen from , the TEM morphology of CNF shows that the average diameter of CNF is 4-10 nm and the length is 1-3 μm.

[0057] Figure 2 The SEM morphology of the prepared core layer composite material is shown in Figure 2 As can be seen from , the SEM morphology of the core layer material shows that the mixing degree of CNF and LNT is high, and LNT is interspersed in CNF.

[0058] Figure 3 The infrared spectrum of the prepared core layer composite material is shown in Figure 3 . -1 Among them, 3429 cm -1 nearby is the stretching vibration peak of -OH, 1610 cm -1 corresponds to the stretching vibration absorption of double bond, 1060 cm -1 nearby is the stretching vibration peak of C-O-C, and the CNF sample also has a glycosidic bond characteristic absorption at 902 cm -1 . Compared with CNF and LNT raw materials, the absorption peaks of -OH and double bond of the composite material are obviously shifted, indicating that good interaction is formed between the two components in the composite material.

[0059] (3) Preparation of shell layer composite material

[0060] The cellulose cotton board was cut into pieces of suitable size, put into a pulverizer for pulverization, and then the cellulose obtained by pulverization was put into an oven for drying at 60℃ for 24h to obtain cotton pulp cellulose (CC). The cotton pulp cellulose was dissolved in a tetrabutylammonium hydroxide / dimethyl sulfoxide (TBAH / DMSO) mixed solution, uniformly dispersed in a planetary mixer to prepare a mixed solution (6g of cotton pulp cellulose, 68.36mL of DMSO, 19.58mL of TBAH (50wt%)). The mixed solution was divided into syringes, and the final material could be smoothly extruded at a speed of 500nm / min at room temperature with the help of a pressure pump to form a shell composite material.

[0061] The above-mentioned tetrabutylammonium hydroxide / dimethyl sulfoxide mixed solvent can effectively dissolve the cotton pulp cellulose, so that the finally obtained shell material has a relatively high viscosity at room temperature and can be used for 3D printing. When the TBAH concentration is less than 50wt%, it is difficult to dissolve the cotton pulp cellulose.

[0062] The SEM morphology diagram of the shell composite material prepared above is shown in Figure 4 It can be known from Figure 4 that the shell material supports the tubular structure of the whole material as a skeleton.

[0063] The infrared spectrum diagram of the shell composite material prepared above is shown in Figure 5 . Figure 5 The peak at 3430cm -1 nearby is the stretching vibration peak of -OH, the peak at 1638cm -1 corresponds to the stretching vibration absorption of a double bond, the peak at 1051cm -1 is the stretching vibration peak of C-O-C, and the glycosidic bond characteristic absorption at 902cm -1 is also present in the CNF sample. Compared with the CC, CNF and LNT raw materials, the absorption peaks of -OH and double bond of the composite material are obviously shifted, indicating that good interaction is formed between the three components in the composite material.

[0064] (4) Preparation of 3D printing fully degradable cellulose and lignin composite self-watering water purification core material

[0065] The water purification core material is based on a cuboid CAD model, and the size and porous structure are designed by slicing software. The coaxial printing pillow auxiliary fixing device model is designed by Simplify3D slicing software. The PLA printing parameters for reference are as follows: nozzle diameter 0.40mm, printing speed 500mm / min, layer thickness 0.30mm, nozzle temperature 240℃.

[0066] The structure schematic diagram of the 3D printing fully degradable cellulose and lignin composite self-watering water purification core material provided by the application is shown in Figure 6 .

[0067] The SEM morphology of the 3D-printed full-degradable cellulose and lignin composite self-water-transporting water purification core material finally prepared by the above method is shown in Figure 7 . It can be seen from Figure 7 that the surface of the composite self-water-transporting water purification core material presents a continuous network structure, and is distributed with many small pores of uniform size. The water filtration channel supported by the shell material is distributed with the core layer composite material, and the tap water sample entering the channel can fully contact with the water purification material.

[0068] Example 2:

[0069] A printing full-degradable cellulose and lignin composite self-water-transporting water purification core material, the preparation method comprising the following steps:

[0070] (1) Preparation of lignin nanotube

[0071] 2 g of dealkalized lignin was added to 100 mL of 20% volume fraction of tetrahydrofuran aqueous solution, stirred at room temperature for 1 h until completely dissolved, then 0.2925 g of sodium chloride (0.05 M) was added and stirred for 1 h, finally the mixed lignin solution was loaded into a dialysis bag, dialyzed at room temperature for 48 h, the dialysate was divided into beakers, liquid ammonia was frozen, and then vacuum freeze-drying machine was used for freeze-drying to obtain lignin nanotube (LNT).

[0072] (2) Preparation of core layer lignin nanotube / nanocellulose composite material (LNT / CNF)

[0073] An equal mass of lignin nanotube and nanocellulose (CNF) was weighed, 20 g of deionized water was added to obtain a mixture, so that the total mass of lignin nanotube and nanocellulose accounted for 3% of the total mass of the mixture, and the mixture was placed in a planetary mixer for dispersion until uniform (10 min each time, 1500 r / min for the first 5 min and 2000 r / min for the last 5 min). The dispersed mixture was loaded into a syringe, loaded into a centrifuge tube and placed in a centrifuge for debubbling; wherein the parameters during debubbling were: 3 min, 2500 r / min, and the core layer lignin nanotube / nanocellulose composite material (LNT / CNF) was finally prepared.

[0074] (3) Preparation of shell layer composite material

[0075] The cellulose cotton board was cut into appropriate size pieces, put into a pulverizer for pulverization, and then the cellulose obtained by pulverization was put into an oven for drying at 60°C for 24h to obtain cotton pulp cellulose (CC). The cotton pulp cellulose was dissolved in a tetrabutylammonium hydroxide / dimethyl sulfoxide (TBAH / DMSO) mixed solution, put into a planetary mixer for uniform dispersion to prepare a mixed solution (6g of cotton pulp cellulose, 68.36mL of DMSO, 19.58mL of TBAH (50wt%)). The mixed solution was divided into syringes, and the final material shell was smoothly extruded at a speed of 500nm / min at room temperature by means of a pressure pump.

[0076] (4) Preparation of 3D printing of fully degradable cellulose and lignin composite self-watering water purification core material

[0077] The water purification core material is based on a cuboid CAD model, the size and porous structure of which are designed by slicing software, and the coaxial printing pillow auxiliary fixing device model is designed by Simplify3D slicing software. The PLA printing parameters for reference are: nozzle diameter 0.40mm, printing speed 500mm / min, layer thickness 0.30mm, nozzle temperature 240°C.

[0078] Example 3:

[0079] A printing of fully degradable cellulose and lignin composite self-watering water purification core material, the preparation method thereof comprising the following steps:

[0080] (1) Preparation of lignin nanotube

[0081] 2g of delignified lignin was added to 100mL of 20% volume fraction tetrahydrofuran aqueous solution, stirred at room temperature for 1h until completely dissolved, then 0.2925g of sodium chloride (0.05M) was added and stirred for 1h, finally the mixed lignin solution was put into a dialysis bag, dialyzed at room temperature for 48h, the dialysate was divided into beakers, liquid ammonia was frozen, and then vacuum freeze-drying machine was used for freeze-drying to obtain lignin nanotube (LNT).

[0082] (2) Preparation of core layer lignin nanotube / nanocellulose composite material (LNT / CNF)

[0083] The same mass of lignin nanotubes and nanocellulose (CNF) was weighed, 20 g of deionized water was added to obtain a mixture, so that the total mass of lignin nanotubes and nanocellulose accounted for 5% of the total mass of the mixture, and the mixture was placed in a planetary mixer for dispersion until uniform (10 min each time, 1500 r / min for the first 5 min and 2000 r / min for the last 5 min). The dispersed mixture was loaded into a needle cylinder, and after being loaded into a centrifuge tube, it was placed in a centrifuge for defoaming; wherein the parameters during defoaming were: 3 min, 2500 r / min, and finally a core layer lignin nanotube / nanocellulose composite material (LNT / CNF) was prepared.

[0084] (3) Preparation of shell layer composite material

[0085] The cellulose cotton board was cut into appropriate size pieces, which were put into a pulverizer for pulverization, and then the cellulose obtained by pulverization was put into an oven for drying at 60°C for 24 h to obtain cotton pulp cellulose (CC). The cotton pulp cellulose was dissolved in a tetrabutylammonium hydroxide / dimethyl sulfoxide (TBAH / DMSO) mixed solution, which was uniformly dispersed in a planetary mixer to prepare a mixed solution (6 g of cotton pulp cellulose, 68.36 mL of DMSO, and 19.58 mL of TBAH (50 wt%)). The mixed solution was divided into needle tubes, and the final material shell was successfully extruded at a speed of 500 nm / min at room temperature with the help of a pressure pump.

[0086] (4) Preparation of 3D printing fully degradable cellulose and lignin composite self-watering water purification core material

[0087] The water purification core material was based on a cuboid CAD model, and the size and porous structure were designed by slicing software. The coaxial printing pillow auxiliary fixing device model was designed by Simplify3D slicing software. The PLA printing parameters for reference were: nozzle diameter 0.40 mm, printing speed 500 mm / min, layer thickness 0.30 mm, and nozzle temperature 240°C.

[0088] Comparative Example 1:

[0089] Comparative Example 1 differs from Example 1 in that Comparative Example 1 uses alkali-free lignin after freeze-drying instead of lignin nanotubes after freeze-drying to prepare the composite water purification core material.

[0090] Through experiments, it was found that the viscosity of the core layer material mixed with alkali-free lignin after freeze-drying and CNF was too low, which would leak out when the core layer material and the shell layer material were 3D printed from the discontinuous part of the printing, affecting the stacking effect between layers, and the final printed sample was loose and difficult to form.

[0091] The composite self-contained water purification core materials prepared in Examples 1-3 have basically the same performance. Taking Example 1 as an example, mechanical performance, water filtration performance, metal ion filtration capacity, and antibacterial capacity tests are conducted on it, as detailed below:

[0092] I. Mechanical Performance Testing

[0093] Test method: Dynamic compression performance was tested using a CMT4000 series test machine under normal ambient temperature, with the crosshead speed kept constant at 50 mm / min during the test.

[0094] Test results are available Figure 8 ,Depend on Figure 8 It is known that the composite self-contained water purification core material provided by the present invention has strong compression resistance, which can better meet the needs when used as a filter element, and prevent the material itself from undergoing excessive deformation due to water pressure, thereby reducing the water filtration capacity.

[0095] II. Water filtration performance test

[0096] Test method: At 25℃, tap water samples were allowed to pass through a sample material of uniform specifications (same cross-sectional area) without external pressure. The volume of liquid filtered by each sample was counted after 1 hour.

[0097] Test Results: The test was conducted using the sample material (sample dimensions: 6*2*1 (cm), cross-sectional area: 2 cm²). 2 The flow rate reached 0.028 L / min. Based on the current market standard for RO membrane filter cartridges with a water flux of 100 G (1 G = 3.78 L / 24 h) (such as the Times Wharton (Huitong) reverse osmosis RO membrane 2012-100G, 48*298 mm, with a cross-sectional area of ​​18 cm²),... 2 (Priced at 60 yuan / piece) It is predicted that, under the same specifications, the water flux of the material of this invention is 362.88L / 24h, that is, the water flux reaches 96G, which is basically the same as the water filtration capacity of the 100G RO membrane filter element on the market (RO membrane filter element water flux is maintained at 95-101G), and higher than the water flux of Joyoung T07 composite ceramic filter element (80-90G). However, the raw material source of this invention is more abundant, the cost is lower, and this invention does not require the addition of auxiliary devices such as pressure pumps. Therefore, it can be seen that the composite self-contained water purification core material provided by this invention has excellent performance.

[0098] III. Metal Ion Filtration Capacity Test

[0099] Test method: Cu and Zn ion solutions similar to domestic sewage were prepared for testing. Samples of the same size (2.2*0.7*0.6 (cm)) were used to filter the ion solutions. The ion concentrations of the solutions before and after filtration were detected by AAS (atomic absorption spectrometry).

[0100] The standard curve test results of Cu ions are shown in Figure 9 The standard curve test results of Zn ions are shown in Figure 10 According to Figure 9 and Figure 10 , the concentrations of Cu ion solution before and after the sample filtration are 1.327 mg / L and 0.862 mg / L respectively, and the filtration performance of the sample on Cu ions is 35.1%; the concentrations of Zn ion solution before and after the sample filtration are 1.380 mg / L and 1.040 mg / L respectively, and the filtration performance of the sample on Zn ions is 24.6% (the ion concentrations before and after the solution filtration are the results of repeated 3 tests). It can be known that the sample has good adsorption capacity on metal ions, and can better achieve the water purification effect in cooperation with activated carbon and other adsorption materials for small particles in water samples.

[0101] When the Haimo reverse osmosis RO membrane 2012-100G is used for testing, the standard curve test results of Cu ions are shown in Figure 11 The standard curve test results of Zn ions are shown in Figure 12 .

[0102] According to Figure 11 and Figure 12 , the concentrations of Cu ion solution before and after the single-layer RO membrane filtration are 1.246 mg / L and 1.165 mg / L respectively, and the filtration performance of the single-layer RO membrane on Cu ions is 6.5%; the concentrations of Zn ion solution before and after the single-layer RO membrane filtration are 0.622 mg / L and 0.591 mg / L respectively, and the filtration performance of the single-layer RO membrane on Zn ions is 5.0% (the ion concentrations before and after the solution filtration are the results of repeated 3 tests). It can be known that the filtration performance of the sample is similar to that of the multi-layer RO with the same cross-sectional area, and the water purification performance meets the requirements of life use.

[0103] The Jiyang T07 composite ceramic filter element is used for testing. According to Figure 11 and Figure 12 , the concentrations of Cu ion solution before and after the ceramic filtration are 1.246 mg / L and 0.0088 mg / L respectively (the test sample solution is the same dilution multiple), and the filtration performance of the ceramic material on Cu ions is 99.3%; the concentrations of Zn ion solution before and after the ceramic filtration are 0.622 mg / L and 0.019 mg / L respectively (the test sample solution is the same dilution multiple), and the filtration performance of the ceramic material on Zn ions is 96.9%. (When the ceramic filter element is tested, the size cannot be controlled to the size of the sample material, so the test results are consistent with the direct use effect in life.)

[0104] The above merely describes preferred embodiments of the present application, and is not used to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a 3D-printed fully degradable cellulose and lignin composite self-watering water purification core material, characterized by, The method comprises the following steps: (1) preparing a core layer composite material Mixing lignin and cellulose, adding deionized water, mixing uniformly, obtaining a mixture, and then centrifuging and defoaming the mixture to obtain the core layer composite material; (2) preparing a shell layer material Dissolving cellulose in a tetrabutylammonium hydroxide / dimethyl sulfoxide mixed solution, then loading into a needle tube and extruding to obtain the shell layer material; (3) preparing a composite self-water-transporting and water-purifying core material The core layer composite material and the shell layer material are combined by 3D printing to obtain the composite self-water-transporting and water-purifying core material. The 3D-printed fully-degradable cellulose and lignin composite self-water-transporting and water-purifying core material prepared by the above method has a core-shell structure, the shell layer comprises cellulose, and the core layer comprises cellulose and lignin; the volume ratio of the core layer material to the shell layer material is 1:3-5; the mass ratio of cellulose to lignin in the core layer is 1:1-3; and the morphology of lignin in the core layer is lignin nanotube.

2. The production method according to claim 1, characterized by, In step (1), the total mass of lignin and cellulose in the mixture accounts for 3-5% of the total mass of the mixture.

3. The preparation method according to claim 1, characterized in that, The lignin has a morphology of lignin nanotube, which is prepared by the following method: adding water, then adding a cosolvent, and finally adding an electrolyte, mixing uniformly, dialyzing, and obtaining the lignin nanotube; or mixing the cosolvent and water to form a cosolvent aqueous solution, then adding lignin, and finally adding an electrolyte, mixing uniformly, dialyzing, and obtaining the lignin nanotube; The electrolyte is any one of sodium chloride, calcium chloride, potassium carbonate, sodium bromide, sodium sulfate, sodium nitrate, copper chloride, copper sulfate, ferrous chloride, ferric chloride, cobalt sulfate, and nickel sulfate; When the electrolyte is sodium chloride, calcium chloride, potassium carbonate, sodium bromide, sodium sulfate, sodium nitrate, copper chloride, or ferrous chloride, the concentration of the electrolyte in the reaction system is 0.01-1 mol / L; when the electrolyte is ferric chloride, the concentration of the electrolyte in the reaction system is greater than or equal to 0.01 mol / L and less than 0.05 mol / L; The cosolvent is methanol, ethanol, ethylene glycol, tetrahydrofuran, dioxane, or N,N-dimethylformamide.

4. The production method according to claim 3, characterized by, The mass concentration of lignin in the cosolvent aqueous solution is 1-20%, and the volume concentration of the cosolvent in the reaction system is 10-90% after adding the cosolvent.

5. The preparation method according to claim 3, characterized in that, The dialysis temperature is 20-60℃, and the dialysis time is 2-4 days.

6. The method of claim 1, wherein, In step (2), the cellulose is dissolved in a tetrabutylammonium hydroxide / dimethyl sulfoxide mixed solution, and the concentration of the cellulose is 5-7 wt%.

7. The production method according to claim 1 or 6, characterized by, In step (2), the volume ratio of tetrabutylammonium hydroxide to dimethyl sulfoxide is 15-25:65-75.

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