Double-network aerogel microbead adsorption material and preparation method thereof

Abstract

The invention provides a dual-network aerogel microbead adsorption material and a preparation method thereof, and belongs to the technical field of adsorption materials, and the preparation method comprises the following steps: weighing one of MgFe2O4 powder and Ti3C2TX powder, adding deionized water, stirring and mixing, and carrying out ultrasonic treatment; adding sodium alginate and kappa-carrageenan into the solution, and stirring and mixing on a magnetic stirrer; after stirring is completed, dropwise adding the mixed solution into a calcium chloride solution by using a peristaltic pump, and standing after all dropwise adding to obtain a spherical precursor; placing the spherical precursor in deionized water for standing to obtain gel balls; placing the gel beads in a culture dish for freeze drying to obtain the dual-network aerogel bead adsorption material. The prepared double-network aerogel microsphere adsorption material is high in heavy metal adsorption capacity and heat stability and can be recycled.

Description

Technical Field

[0001] The invention belongs to the technical field of adsorption materials, and in particular relates to a double-network aerogel microbead adsorption material and a preparation method thereof. Background Art

[0002] Aerogel is a porous material with extremely high porosity and extremely low density, which is widely used in adsorption, heat insulation, sound insulation and other fields. Its unique microstructure gives aerogel excellent adsorption properties, making it perform well in environmental remediation, gas storage, catalyst carrier and other aspects.

[0003] Sodium alginate is a natural high molecular weight substance extracted from algae. Its molecular formula is (C 6 H 7 NaO 6 ) n , with a wide range of sources and easy to obtain, the sodium alginate content in kelp is as high as 30% to 40%, which is also the main component of the cell wall of brown algae. It can be degraded by microorganisms, is non-toxic and non-irritating, has good biocompatibility, and will not cause environmental pollution. The aerogel prepared using sodium alginate can form a highly loose and porous structure with a high specific surface area and porosity, enabling it to absorb dozens of times its own weight in water, and the preparation method usually includes four steps of sol-gelation, cross-linking, solvent exchange and drying. These steps are easy to operate and do not require complex equipment. These characteristics make sodium alginate aerogel have broad application prospects in the field of adsorption, especially in the fields of environmental governance, biomedicine and food industry.

[0004] However, due to the structure of sodium alginate itself, the currently prepared sodium alginate aerogel has low thermal stability, weak adsorption capacity for heavy metals, and poor recycling effect after absorption saturation. How to give full play to the adsorption capacity of sodium alginate aerogel in heavy metals is a difficult problem that needs to be solved urgently. Summary of the invention

[0005] The purpose of the present invention is to provide a double-network aerogel microbead adsorption material and a preparation method thereof, so as to solve the problem that aerogels made of pure sodium alginate have unsatisfactory heavy metal adsorption performance and low thermal stability.

[0006] The technical solution adopted by the present invention is a method for preparing a double-network aerogel microbead adsorption material, comprising the following steps:

[0007] S1. Weighing MgFe 2 O 4 Powder, Ti 3 C 2 T X One of the powders was added with deionized water, stirred and mixed, and subjected to ultrasonic treatment;

[0008] S2, adding sodium alginate and κ-carrageenan to the solution, placing on a magnetic stirrer and stirring to mix;

[0009] S3. After the stirring is completed, the mixed solution is dripped into the calcium chloride solution using a peristaltic pump, and the mixture is allowed to stand after all the solution is dripped in to obtain a spherical precursor;

[0010] S4, placing the spherical precursor in deionized water and letting it stand to obtain gel spheres;

[0011] S5. Place the gel balls in a culture dish and freeze-dry them to obtain double-network aerogel microbead adsorption materials.

[0012] Further, in step S1, the MgFe 2 O 4 Powder, Ti 3 C 2 T X The mass of the powder is 0.1-2 g, and the volume of the deionized water is 100-500 mL.

[0013] Furthermore, in step S1, the ultrasonic time is 10-25 min, and the ultrasonic frequency is 28-32 Hz.

[0014] Furthermore, in step S2, the mass of the sodium alginate is 0.3-4 g, and the mass of the κ-carrageenan is 0.2-4 g.

[0015] Furthermore, in step S2, the stirring speed of the magnetic stirrer is 600-800RPM, and the stirring time is 2-4h.

[0016] Furthermore, in step S3, the concentration of the calcium chloride solution is 1.0-5.0 g / L, and the standing time is 4-12 h.

[0017] Furthermore, in step S4, the standing time is 4-12 hours.

[0018] Furthermore, in step S5, the freeze drying is to freeze the gel balls to 0°C at -40°C to -50°C.

[0019] A double-network aerogel microbead adsorption material is prepared by adopting the above preparation method.

[0020] Beneficial effects of the present invention:

[0021] (1) The present invention selects κ-carrageenan and sodium alginate as the base for cross-linking to form a double-network structure aerogel. Compared with the traditional single-network aerogel, the mechanical properties are further enhanced, the pore structure is denser, and it has higher strength. It can withstand high levels of tensile and compressive deformation and has a lower swelling rate, so that the aerogel can accommodate a large amount of water while maintaining a stable morphology and network structure. In addition, due to its unique cross-linking method, it also has the ability of rapid self-repair.

[0022] (2) The present invention selects spinel ferrite magnetic material MgFe 2 O 4 MXene materials are compounded with κ-carrageenan and sodium alginate, MgFe 2 O 4 MXene materials have the advantages of high specific surface area, strong stability, easy modification, and adjustable size and shape. They have excellent compatibility with aerogels and avoid the problem of incomplete separation of κ-carrageenan and sodium alginate at the nanoscale. 2 O 4 The magnetism of aerogel can also improve its adsorption capacity for heavy metals, and it can use its own magnetism to separate them from aqueous solutions for secondary utilization.

[0023] (3) The present invention uses calcium chloride as a cross-linking agent and sodium alginate as a substrate. The sodium ions in the sodium alginate are easily replaced by the calcium ions in the calcium chloride. The reaction time is short. The drying method adopts freeze drying. The experimental operation is simple and the cost is low. The final product is a gel ball, which is more conducive to recovery. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 Schematic diagram of the double-network aerogel microbead adsorption material prepared in Example 2 of the present invention.

[0026] Figure 2 Schematic diagram of the magnetic properties of the double-network aerogel microbead adsorption material prepared in Example 2 of the present invention, wherein a magnetic field is not added in FIG (a), and a magnetic field is added in FIG (b).

[0027] Figure 3 It is a fitting diagram of the isothermal adsorption model of the double-network aerogel microbead adsorption material prepared in Example 2 of the present invention.

[0028] Figure 4: is a schematic diagram of fitting the quasi-second-order kinetic adsorption model of the double-network aerogel microbead adsorption material prepared in Example 2 of the present invention, Figure 4 (a) is the adsorption of Cd 2+ The fitting diagram of Figure 4 (b) is the adsorption of Sb(OH) 6 - The fitting diagram of .

[0029] Figure 5 This is a relationship diagram between the adsorption times and the adsorption amount of the double network aerogel microbead adsorption material prepared in Example 2 of the present invention.

[0030] Figure 6 This is a thermogravimetric analysis diagram of the double-network aerogel microbead adsorption material prepared in Example 2 of the present invention.

[0031] Figure 7 This is a SEM image of the double-network aerogel microbead adsorption material prepared in Example 7 of the present invention.

[0032] Figure 8 This is a thermogravimetric analysis diagram of the double-network aerogel microbead adsorption material prepared in Example 7 of the present invention.

[0033] Fig. 9 is a fitting diagram of the isothermal adsorption model of the double network aerogel microbead adsorption material prepared in Example 7 of the present invention, Fig. 9 (a) is the adsorption of Sb(OH) 6- The fitting diagram of Fig. 9 (b) Pb adsorption 2+ The fitting diagram of Fig. 9 (c) is the adsorption of Cd 2+ The fitting diagram of .

[0034] Fig.10 It is a schematic diagram of fitting the quasi-second-order kinetic adsorption model of the double-network aerogel microbead adsorption material prepared in Example 7 of the present invention. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] Example 1

[0037] A method for preparing a double-network aerogel microbead adsorption material comprises the following steps:

[0038] S1. Weigh 0.1g MgFe 2O 4 Powder, add 100 mL of deionized water, stir and mix, and perform ultrasonic treatment, setting the ultrasonic time to 20 min and the ultrasonic frequency to 30 kHz;

[0039] S2. Add 1.5 g of sodium alginate and 1 g of κ-carrageenan to the solution, place on a magnetic stirrer and stir to mix. The stirring speed of the magnetic stirrer is 800 RPM and the stirring time is 4 h.

[0040] S3. After stirring, the mixed solution is dripped into the calcium chloride solution using a peristaltic pump, the concentration of calcium chloride is 3 g / L, and after all the solution is dripped in, it is allowed to stand for 10 hours to obtain a spherical precursor;

[0041] S4, placing the spherical precursor in deionized water and letting it stand for 10 hours to obtain gel spheres;

[0042] S5. Place the gel balls in a culture dish for freeze drying, freeze the gel balls to 0°C at -50°C to obtain a double-network aerogel microbead adsorption material.

[0043] Example 2

[0044] A method for preparing a double-network aerogel microbead adsorption material comprises the following steps:

[0045] S1. Weigh 0.5g MgFe 2 O 4 Powder, add 100 mL of deionized water, stir and mix, and perform ultrasonic treatment, setting the ultrasonic time to 10 min and the ultrasonic frequency to 28 kHz;

[0046] S2, add 0.3g sodium alginate and 0.2g kappa-carrageenan to the solution, place on a magnetic stirrer and stir to mix, the stirring speed of the magnetic stirrer is 600RPM, and the stirring time is 2h;

[0047] S3. After stirring, the mixed solution is dripped into the calcium chloride solution using a peristaltic pump, the concentration of calcium chloride is 1 g / L, and after all the solution is dripped in, it is allowed to stand for 4 hours to obtain a spherical precursor;

[0048] S4, placing the spherical precursor in deionized water and letting it stand for 4 hours to obtain a gel sphere;

[0049] S5. Place the gel balls in a culture dish for freeze drying, freeze the gel balls to 0°C at -40°C to obtain a double-network aerogel microbead adsorption material.

[0050] Example 3

[0051] A method for preparing a double-network aerogel microbead adsorption material comprises the following steps:

[0052] S1. Weigh 1.5g MgFe 2 O 4 Powder, add 500 mL of deionized water, stir and mix, and perform ultrasonic treatment, setting the ultrasonic time to 20 min and the ultrasonic frequency to 32 kHz;

[0053] S2. Add 4 g of sodium alginate and 4 g of κ-carrageenan to the solution, place on a magnetic stirrer and stir to mix. The stirring speed of the magnetic stirrer is 800 RPM and the stirring time is 4 h.

[0054] S3. After the stirring is completed, the mixed solution is dripped into the calcium chloride solution using a peristaltic pump, the calcium chloride concentration is 5 g / L, and after all the dripping is completed, it is allowed to stand for 12 hours to obtain a spherical precursor;

[0055] S4, placing the spherical precursor in deionized water and letting it stand for 12 hours to obtain gel spheres;

[0056] S5. Place the gel balls in a culture dish for freeze drying, freeze the gel balls to 0°C at -40°C to obtain a double-network aerogel microbead adsorption material.

[0057] Example 4

[0058] The difference from Example 1 is that in step S1, 1 g MgFe 2 O 4 powder, set the ultrasonic time to 15min; in step S2, add 1.2g sodium alginate, the stirring speed of the magnetic stirrer is 700RPM, and the stirring time is 3h; in step S3, after all are dropped, let stand for 8h; in step S4, let stand for 8h. The remaining steps are the same as in Example 1.

[0059] Example 5

[0060] The difference from Example 3 is that in step S1, 2 g MgFe 2 O 4 The remaining steps are the same as those in Example 3.

[0061] Example 6

[0062] The difference from Example 2 is that in step S1, 0.1 g Ti 3 C 2 T X The powder is added with 200 mL of deionized water and stirred and mixed, and the ultrasonic time is 10 min; in step S5, it is frozen at -40°C. The remaining steps are the same as in Example 2.

[0063] Example 7

[0064] The difference from Example 1 is that in step S1, 0.5 g Ti3 C 2 T X powder; in step S2, the stirring speed is set to 700RPM and the stirring time is 1 hour; in step S3, the concentration of calcium chloride is 3.0g / L, and after all is dropped in, it is left to stand for 8 hours; in step S4, the standing time is 8 hours. The remaining steps are the same as in Example 1.

[0065] Example 8

[0066] The difference from Example 2 is that in step S1, 1 g Ti 3 C 2 T X The powder was added with 100 mL of deionized water and stirred, and the ultrasonic time was set to 20 min and the ultrasonic frequency was set to 30 kHz. The remaining steps were the same as in Example 2.

[0067] Example 9

[0068] The difference from Example 1 is that in step S1, 1.5 g Ti 3 C 2 T X The powder was added with 200 mL of deionized water and stirred; in step S2, 2.5 g of sodium alginate and 2 g of κ-carrageenan were added, the stirring speed of the magnetic stirrer was 700 RPM, and the stirring time was 3 h; in step S4, the standing time was 8 h; in step S5, the standing time was 8 h. The remaining steps were the same as in Example 1.

[0069] Example 10

[0070] The difference from Example 3 is that in step S1, 2 g Ti 3 C 2 T X The ultrasonic time is set to 25 min. The remaining steps are the same as those in Example 3.

[0071] Comparative Example 1

[0072] The difference from Example 1 is that MgFe is not added in step S1. 2 O 4 , without stirring and ultrasonic treatment. The remaining steps are the same as in Example 1.

[0073] Comparative Example 2

[0074] The difference from Example 6 is that Ti is not added in step S1. 3 C 2 T X The remaining steps are the same as in Example 6.

[0075] Comparative Example 3

[0076] The difference from Example 1 is that in step S1, 0.01 g MgFe 2 O 4 In step S2, 0.1 g of sodium alginate and 5 g of κ-carrageenan are added. The remaining steps are the same as those in Example 1.

[0077] Comparative Example 4

[0078] The difference from Example 1 is that in step S1, 0.01 g MgFe 2 O 4 The remaining steps are the same as those in Example 1.

[0079] Comparative Example 5

[0080] The difference from Example 1 is that in step S1, 2.5 g MgFe 2 O 4 The remaining steps are the same as those in Example 1.

[0081] Comparative Example 6

[0082] The difference from Example 7 is that in step S1, 0.01 g Ti 3 C 2 T X The remaining steps are the same as in Example 7.

[0083] Comparative Example 7

[0084] The difference from Example 7 is that in step S1, 2.5 g Ti 3 C 2 T X The remaining steps are the same as in Example 7.

[0085] Comparative Example 8

[0086] The difference from Example 1 is that in step S2, 0.2 g of sodium alginate is weighed. The remaining steps are the same as in Example 1.

[0087] Comparative Example 9

[0088] The difference from Example 1 is that in step S2, 5 g of sodium alginate is weighed. The remaining steps are the same as in Example 1.

[0089] Comparative Example 10

[0090] The difference from Example 1 is that in step S3, the concentration of calcium chloride is 0.5 g / L. The remaining steps are the same as in Example 1.

[0091] Comparative Example 11

[0092] The difference from Example 1 is that in step S3, the concentration of calcium chloride is 6 g / L. The remaining steps are the same as in Example 1.

[0093] Comparative Example 12

[0094] The difference from Example 1 is that in step S3, the standing time is 3 hours. The remaining steps are the same as in Example 1.

[0095] Comparative Example 13

[0096] The difference from Example 1 is that in step S3, the standing time is 13 hours. The remaining steps are the same as in Example 1.

[0097] Comparative Example 14

[0098] The difference from Example 1 is that in step S4, the standing time is 3 hours. The remaining steps are the same as in Example 1.

[0099] Comparative Example 15

[0100] The difference from Example 1 is that in step S4, the standing time is 13 hours. The remaining steps are the same as in Example 1.

[0101] Comparative Example 16

[0102] The difference from Example 1 is that freeze drying is not performed in step S5. The remaining steps are the same as in Example 1.

[0103] The present invention selects to add calcium chloride as a crosslinking agent. The calcium ions in the calcium chloride can react with κ-carrageenan and sodium alginate to form a crosslinking reaction. Sodium alginate has a high content of carboxyl groups, which can react with calcium ions to form an aerogel network. Due to electrostatic attraction, κ-carrageenan can form an aerogel network with a bridging structure with calcium ions. In addition to forming their own aerogel networks, the aerogel network formed by sodium alginate can also form a double network aerogel structure through calcium ions and sulfate groups of κ-carrageenan. The Ti used in the present invention 3 C 2 T X It is a typical MXene material, and its surface functional groups T X Including -O, -OH, -F.

[0104] The double network aerogel microbeads prepared in the embodiments of the present invention and the comparative examples were tested for the Cd concentration of 200 mg / L. 2 + 、Sb(OH) 6 - The saturated adsorption capacity of the solution and the test results are shown in Table 1.

[0105] Table 1 Adsorption performance test data

[0106]

[0107]

[0108] From Table 1, we can see that the Cd 2+ 、Sb(OH) 6 - The adsorption capacity of the samples decreased significantly, mainly because no MgFe was added. 2 O 4 Powder or Ti 3 C 2 T X The addition of these two provides more active sites for the double-network aerogel structure formed by sodium alginate and κ-carrageenan, and significantly improves the adsorption performance.

[0109] Comparative Examples 3 and 4 both add MgFe below the range of the embodiments of the present invention. 2 O 4 Powder, MgFe 2 O 4 The active sites provided by the powder are reduced, which reduces the performance of the adsorption material; in Comparative Example 3, sodium alginate and κ-carrageenan are added in an amount exceeding the range of the embodiment of the present invention, resulting in the adsorption performance of Comparative Example 3 being slightly lower than that of Comparative Example 4. This is because the double network structure formed by sodium alginate and κ-carrageenan is uneven, and it is difficult for pollutants to enter the active sites of the aerogel microbeads, resulting in a decrease in the adsorption performance; in Comparative Example 5, MgFe 2 O 4 Powder, due to its high content, MgFe 2 O 4 It cannot be fully dissolved and forms precipitation that blocks active sites.

[0110] Comparative Examples 6 and 7 both add Ti beyond the scope of the embodiments of the present invention. 3 C 2 T X Powder, Ti 3 C 2 T X The powder can be modified by cross-coupling reaction with sodium alginate and κ-carrageenan, but too much Ti 3 C 2 T X Powder will cause agglomeration and form larger particles, resulting in decreased adsorption performance. 3 C 2 T X The adsorption enhancement effect produced by powder is not obvious.

[0111] Comparative Examples 8 and 9 both add sodium alginate beyond the scope of the embodiments of the present invention. If the sodium alginate content is too low, it will result in the inability to form a uniform and continuous double network structure with κ-carrageenan, lacking sufficient polymer chains to maintain the integrity of the double network, and having structural defects; while if the sodium alginate content is too high, the formed network structure will be too dense, the porosity will be significantly reduced, and it will be difficult for pollutants to enter the active sites inside the material, resulting in a decrease in adsorption performance.

[0112] Comparative Examples 10 and 11 both add calcium chloride beyond the scope of the embodiments of the present invention. When the concentration of calcium chloride is too high, the double network structure in the aerogel microbeads is too dense, the permeability is reduced, and the pollutants are affected from entering the interior, thereby reducing the adsorption performance. When the concentration of calcium chloride is too high, it cannot provide enough calcium ions to participate in the cross-linking reaction, and a complete double network structure cannot be formed, the specific surface area decreases, and the adsorption performance is reduced.

[0113] Comparative Examples 12 and 13 are both set beyond the standing time range of calcium chloride in the embodiment of the present invention. If the standing time is too short, the calcium chloride will not be able to fully cross-link with the sodium alginate. If the standing time is too long, the aerogel microbeads will begin to absorb moisture, and the moisture will occupy its effective active sites, resulting in a decrease in adsorption performance or failure.

[0114] Comparative Examples 14 and 15 are both set to exceed the standing time range of the embodiments of the present invention in deionized water. Deionized water can remove excess calcium ions in the aerogel, which is beneficial to exposing more active sites and increasing the specific surface area. If the standing time is too short, impurity ions occupy the internal space of the microbeads, which greatly reduces the exposed active sites and reduces the pollutant adsorption efficiency. If the standing time is too long, the aerogel microbeads absorb excessive water, and the water will occupy its effective active sites, resulting in a decrease in adsorption performance or failure. In addition, long-term immersion in water is prone to the growth of microorganisms, which destroys the performance and stability of the aerogel microbeads, prolongs the production cycle, and reduces work efficiency.

[0115] Comparative Example 16 did not perform freeze drying. The freeze drying of the present invention can maintain the effective active sites, colloidal morphology and porous structure of the aerogel microbeads, protect the easily oxidizable substances and extend the shelf life, and can greatly improve the rehydration property after the solution to be treated is added.

[0116] The double network aerogel microbead adsorption material prepared in Example 2 of the present invention is shown in FIG. Figure 1 As shown in the figure, it is in granular form after freeze drying, and the state of soaking it in the solution is as follows Figure 2 As shown in (a), it can be seen that the aerogel microbeads absorbed a large amount of solution, causing the volume to expand, reflecting its good adsorption capacity. Figure 2 (b) Aerogel microbeads float in the solution and cling to the magnet under an applied magnetic field, indicating that the addition of MgFe 2 O4 The aerogel microbeads have good magnetic properties, which can make the aerogel microbeads absorb more heavy metal ions.

[0117] like Figure 3 As shown, the double network aerogel microbead adsorption material prepared in Example 2 of the present invention is effective for the adsorption of pollutants Sb(OH) 6 - Schematic diagram of the Freundlich isotherm adsorption model at different concentrations. It can be seen from the figure that when the equilibrium liquid concentration (C e ) in the range of 0 to 100 mg / L, its equilibrium adsorption capacity (q e ) has the fastest rising rate. With the increase of equilibrium liquid concentration, the equilibrium adsorption amount gradually increases. When the equilibrium liquid concentration reaches 200 mg / L, the rising rate of equilibrium adsorption amount gradually slows down. The correlation coefficient (R 2 ) is 0.87, and the adsorption behavior conforms to the Freundlich isotherm adsorption model, which indicates that the double-network aerogel microbeads can perform multilayer adsorption on different active sites.

[0118] like Figure 4 , which is a schematic diagram of fitting the quasi-second-order kinetic adsorption model of the double-network aerogel microbead adsorption material prepared in Example 2 of the present invention, Figure 4 (a) is the initial adsorption concentration of Cd at 100 mg / L 2+ The pseudo-second-order kinetic adsorption model fitting diagram, Figure 4 (b) is the initial adsorption concentration of Sb(OH) at 200 mg / L 6 - The quasi-second-order kinetic adsorption model fitting diagram shows that the double-network aerogel microbead adsorption material prepared by the present invention has good adsorption performance in the adsorption of Cd 2+ 、Sb(OH) 6 - The maximum adsorption capacity was reached within 30 minutes, which reflects its good adsorption efficiency. The correlation coefficient of the pseudo-second-order kinetic adsorption model fitting reached 0.99, which was consistent with the pseudo-second-order kinetic adsorption model, indicating that the adsorption process was controlled by surface reaction and belonged to chemical adsorption process.

[0119] like Figure 5 As shown in the figure, it is a relationship diagram between the adsorption times and the adsorption amount of the double network aerogel microbeads prepared in Example 2 of the present invention, for the pollutant Cd with a concentration of 200 mg / L 2+ 0.1 g / L double network aerogel microbeads were added to the solution, and after adsorption, a magnetic field was applied for magnetic separation, and then the adsorbent was immersed in 0.01 mol / L NaOH solution for 2 h to recover the adsorbent material, and the adsorption experiment was repeated. The results showed that the double network aerogel microbeads had a good adsorption performance on Cd 2+The adsorption capacity of the first adsorption experiment was about 400 mg / g, and the adsorption capacity of the second adsorption experiment dropped to about 180 mg / g. After 6 cycles, the adsorption capacity of the magnetic microbead adsorption material was still stable at 130 mg / g, showing good adsorption performance and recyclability.

[0120] like Figure 6 As shown in the figure, it is a thermogravimetric analysis diagram of the double network aerogel microbeads prepared in Example 2 of the present invention. It can be seen from the figure that when the temperature rises from room temperature to 880°C, the double network aerogel microbeads undergo three relatively obvious mass loss processes. The temperature of the first mass loss is 25°C to 160°C. During this process, the mass of the aerogel microbeads loses about 14.5%, mainly due to the loss of internal crystalline water; the mass loss of the second mass loss occurs between 160°C and 560°C, among which the loss rate between 200°C and 320°C is the fastest, which is also the temperature range with the most mass loss during the experiment. This section is mainly due to the thermal decomposition of most of the κ-carrageenan and sodium alginate inside the aerogel microbeads, resulting in a rapid decrease in the mass of the material. In this stage, the mass of the material is reduced by about 37.1%; in the third stage, the κ-carrageenan and sodium alginate inside the material are crosslinked by the crosslinking agent CaCl 2 The influence of magnesium ferrite resulted in incomplete carbonization, that is, between 560℃ and 880℃, the mass lost about 15.3% in this stage. After the temperature reached 880℃, the mass of the material was 33.1% left, but the weight loss rate of the material was not equal to zero at this time, indicating that if the temperature continued to rise, the weight of the material would decrease to a certain extent. The decomposition temperature of magnesium ferrite material was above 1200℃, indicating that magnesium ferrite did not decompose at this time, and a certain mass of aerogel microbeads still existed. The experimental analysis showed that the double network aerogel microbead adsorption material had good thermal stability, which could prevent the microbeads from leaking and thus affecting its adsorption performance.

[0121] like Figure 7 As shown, this is a SEM image of the double-network aerogel microbeads prepared in Example 7 of the present invention. It can be seen from the figure that the surface of the double-network aerogel microbeads has many tiny depressions and protrusions. This structure can significantly increase the specific surface area of ​​the aerogel microbeads, increase the surface roughness, and further improve the efficiency of the adsorption process.

[0122] like Figure 8As shown, it is a thermogravimetric analysis diagram of the double network aerogel microbead adsorption material prepared in Example 7 of the present invention. It can be seen from the figure that the DTG curve of the double network aerogel microbead adsorption material has three peaks. The first peak is relatively steep, and the latter two peaks can be regarded as a thermodynamic process. From the TG curve in the figure, the corresponding two-stage loss process can be found. From the temperature range of 40℃~225℃, the TG curve drops rapidly, and the mass loss is 17.5%. The main reason for this phenomenon is that the adsorbed water is removed due to the increase in temperature, so the mass decreases; when the temperature continues to rise, it can be found from the TG curve that from 225℃ to 740℃, the TG curve drops faster again, and the mass decreases by 39%, but the rate of decrease begins to become slow and gradually stabilizes. This determines that this stage is mainly because the temperature increase causes κ-carrageenan and sodium alginate to undergo thermal decomposition, and this decomposition will lead to a further reduction in the sample mass. Experimental analysis shows that the double network aerogel microbead adsorption material has good thermal stability.

[0123] like Fig. 9 , which is a schematic diagram of the Langmuir isotherm adsorption model of the double network aerogel microbead adsorption material prepared in Example 7 of the present invention, Fig. 9 (a) is for Sb(OH) at a concentration of 500 mg / L 6- Isotherm adsorption fitting curve of the solution, Fig. 9 (b) is for Pb concentration of 600 mg / L 2+ Isothermal adsorption fitting curve of the solution; Fig. 9 (c) is for Cd concentration of 700 mg / L 2+ Isothermal adsorption fitting curve; from the figure, it can be seen that when the equilibrium liquid concentration is between 0 and 100 mg / L, the equilibrium adsorption amount gradually increases with the increase of the equilibrium liquid concentration, and then with the increase of the equilibrium liquid concentration, the rate of increase of the equilibrium adsorption amount gradually slows down and reaches the maximum adsorption capacity. This is because at the beginning of adsorption, the double network aerogel microbead adsorption material has many effective adsorption active sites and a large adsorption capacity. The equilibrium adsorption amount increases with the increase of Pb 2+ 、Cd 2+ and Sb(OH) 6 - As the concentration increases, the active sites are gradually occupied. When almost all active sites are occupied, the equilibrium adsorption amount no longer increases with the concentration of Pb 2+ 、Cd 2+ and Sb(OH) 6 - The Langmuir isotherm adsorption model has a correlation coefficient R 2 All of them are above 0.96, and the adsorption behavior conforms to the Langmuir isotherm adsorption model.

[0124] like Fig.10 , which is a schematic diagram of fitting the quasi-second-order kinetic adsorption model of the double-network aerogel microbead adsorption material prepared in Example 7 of the present invention, Fig.10 (a) Sb(OH) 6 - Fitting, Fig.10 (b) is Cd 2+ Fitting. From the figure, we can see that within the first 10 minutes of the adsorption reaction, the adsorption amount of the material increases rapidly, and reaches adsorption equilibrium after 30 minutes. The maximum adsorption amount can be reached in a short time.

[0125] Each embodiment in this specification is described in a related manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0126] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A method for preparing a double network aerogel microbead adsorption material, characterized in that: The following steps are involved: S1. Weigh MgFe2O4 powder, Ti3C2T X One of the powders was added with deionized water, stirred and mixed, and subjected to ultrasonic treatment; S2, adding sodium alginate and κ-carrageenan to the solution, placing on a magnetic stirrer and stirring to mix; S3. After the stirring is completed, the mixed solution is dripped into the calcium chloride solution using a peristaltic pump, and the mixture is allowed to stand after all the solution is dripped in to obtain a spherical precursor; S4, placing the spherical precursor in deionized water and letting it stand to obtain gel spheres; S5. Place the gel balls in a culture dish and freeze-dry them to obtain double-network aerogel microbead adsorption materials.

2. The method for preparing a double network aerogel microbead adsorption material according to claim 1, characterized in that: In step S1, the MgFe2O4 powder, Ti3C2T X The mass of the powder is 0.1-2 g, and the volume of the deionized water is 100-500 mL.

3. The method for preparing a double network aerogel microbead adsorption material according to claim 1, characterized in that: In step S1, the ultrasonic time is 10-25 min, and the ultrasonic frequency is 28-32 Hz.

4. The method for preparing a double network aerogel microbead adsorption material according to claim 1, characterized in that: In step S2, the mass of the sodium alginate is 0.3-4 g, and the mass of the κ-carrageenan is 0.2-4 g.

5. The method for preparing a double network aerogel microbead adsorption material according to claim 1, characterized in that: In step S2, the stirring speed of the magnetic stirrer is 600-800RPM, and the stirring time is 2-4h.

6. The method for preparing a double network aerogel microbead adsorption material according to claim 1, characterized in that: In step S3, the concentration of the calcium chloride solution is 1.0-5.0 g / L, and the standing time is 4-12 h.

7. The method for preparing a double network aerogel microbead adsorption material according to claim 1, characterized in that: In step S4, the standing time is 4-12 h.

8. The method for preparing a double network aerogel microbead adsorption material according to claim 1, characterized in that: In step S5, the freeze drying is to freeze the gel balls to 0°C at -40°C to -50°C.

9. A double network aerogel microbead adsorption material, characterized in that: The method is prepared by the method according to any one of claims 1 to 8.

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