Spherical hydrotalcite-like alginate hydrogel adsorbent and preparation method and application thereof

Abstract

The present invention belongs to the technical fields of wastewater treatment and adsorbent materials, and particularly relates to a spherical hydrotalcite-like - sodium alginate adsorbent, a preparation method thereof, and an application. The preparation method of the spherical hydrotalcite-like - sodium alginate adsorbent provided by the present invention uses six metal salts as raw materials for preparing LDHs, uses triethanolamine as an alkali source, and prepares LDHs powder with high adsorption performance by a hydrothermal method. Then, the LDHs powder is compounded with sodium alginate to obtain solid particle hydrogel beads. The hydrogel bead adsorbent is easy to recycle and can greatly improve the treatment effect of the adsorbent on organic pollutant wastewater. Through adsorption tests, the adsorption capacity for the organic dye Congo red (CR) can reach more than 4400 mg / g, far higher than the capacity of the adsorbent materials developed at home and abroad at present, and the number of times of reuse can be as high as more than 8 times, having broad application prospects in the treatment application of industrial wastewater.

Description

Technical Field

[0001] The present invention belongs to the technical fields of wastewater treatment and adsorption materials, and particularly relates to a spherical hydrotalcite-like-alginate adsorbent, a preparation method thereof, and an application thereof. Background Art

[0002] Pollutants released by human activities have a significant impact on the earth's water ecosystem, and the illegal discharge of wastewater has become a global environmental problem that cannot be ignored. With the rapid development of modern industry, various factories will discharge a large amount of polluted wastewater. For example, industries such as textile, printing, papermaking, food processing, and leather making will generate a large amount of dye wastewater. Various pollutants or xenobiotics contained in the dye wastewater will pose a serious threat to human health and the aquatic system. In particular, with the increasing utilization of organic compounds such as cosmetics, antibiotics, spices, sweeteners, veterinary drugs, agrochemicals, and pesticides in modern society, various hazardous pollutants that have a negative impact on the surrounding environment will also be generated. Among them, dye pollutants existing in the water environment usually have long-term stable biological and structural activities, and their long-term existence will also cause adverse consequences to microbial activities in nature. Therefore, how to effectively remove dye pollutants in wastewater has become a long-term exploration topic for scientific researchers.

[0003] Currently, compared with other treatment methods, the adsorption method for treating industrial wastewater has the characteristics of being economically feasible, easy to operate, and highly efficient, and is considered an effective strategy for removing pollutants in water. At present, some conventional adsorbents such as activated carbon, fly ash, bentonite, and zeolite are often used in industry for wastewater purification. However, traditional adsorbents often have limitations such as low adsorption efficiency, poor hydrophobicity, small adsorption capacity, and difficulty in repeated utilization, which limit their application in the removal of wastewater pollutants.

[0004] Hydrotalcite-like compounds are also known as Layered Double Hydroxides (LDHs for short). Due to the adjustable nature of metal cation types, anion exchangeability, and large specific surface area, they have various physical and chemical properties and can be used as adsorption materials. Currently, methods for preparing LDHs include urea hydrolysis method, coprecipitation method, etc. Although LDHs adsorbent materials can be prepared by conventional methods, they still have problems such as low adsorption capacity and few repeated utilization times.

[0005] Therefore, the development of new adsorbents with high adsorption capacity, high adsorption efficiency, and capable of being recycled is of great significance for both wastewater treatment and environmental protection. Summary of the Invention

[0006] In view of this, the object of the present invention is to provide a preparation method of a spherical hydrotalcite-like-sodium alginate adsorbent, which has a simple process and can prepare a green spherical particle adsorbent with low cost, high adsorption capacity and high reuse rate, and can efficiently treat pollutant wastewater, effectively solving the problems of low adsorption capacity of the current adsorbent and difficulty in reuse.

[0007] Meanwhile, another object of the present invention is to provide a spherical hydrotalcite-like-sodium alginate adsorbent and its application.

[0008] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] A preparation method of a spherical hydrotalcite-like-sodium alginate adsorbent comprises the following steps:

[0010] (1) Mix zinc nitrate, manganese nitrate, nickel nitrate, copper nitrate, chromium nitrate, aluminum nitrate with water, add triethanolamine under stirring conditions, continuously stir, then place it in a high-pressure reaction kettle, carry out hydrothermal reaction at 100 - 120 °C for 2 - 4 h, wash and dry the generated product to obtain LDHs nano-powder;

[0011] (2) Uniformly disperse the LDHs nano-powder obtained in step (1) in water to obtain an LDHs dispersion liquid, then drop the LDHs dispersion liquid into an aqueous sodium alginate solution, and stir evenly to obtain a mixed slurry;

[0012] (3) Add the mixed slurry obtained in step (2) into an aqueous calcium chloride solution to form polymer beads, then solidify and wash to obtain the spherical hydrotalcite-like-sodium alginate adsorbent.

[0013] As a further preferred scheme, in step (1), the molar ratio of zinc nitrate, manganese nitrate, nickel nitrate, copper nitrate, chromium nitrate, aluminum nitrate is 1:1:1:1:1:1.

[0014] As a further preferred scheme, in step (1), for every 1.6 - 1.7 mmol of zinc nitrate, the amount of water used is 10 - 14 mL, and the amount of triethanolamine used is 1 - 3 mL.

[0015] As a further preferred scheme, in step (2), in the LDHs dispersion liquid, for every 0.2 g - 0.25 g of LDHs nano-powder, the amount of water used is 10 - 15 mL.

[0016] As a further preferred scheme, in step (2), in the aqueous sodium alginate solution, for every 0.2 g - 0.25 g of sodium alginate, the amount of water used is 10 - 15 mL.

[0017] As a further preferred scheme, in step (2), the stirring time is 6 - 8 h.

[0018] As a further preferred solution, in step (3), the concentration of the calcium chloride aqueous solution is 0.1 - 0.2 mol / L.

[0019] As a further preferred solution, in step (3), the curing time is 10 - 15 h.

[0020] A spherical hydrotalcite - sodium alginate adsorbent prepared by the preparation method as described above.

[0021] An application of the spherical hydrotalcite - sodium alginate adsorbent as described above, specifically an application as an adsorbent material for removing dye pollutants in water.

[0022] As a further preferred solution, the dye pollutant is one or two of congo red and methyl orange.

[0023] The beneficial effects of the present invention are as follows:

[0024] The preparation method of the spherical hydrotalcite - sodium alginate adsorbent provided by the present invention simultaneously uses six metal salts as raw materials for preparing LDHs, and uses triethanolamine as the base source. A high - adsorption - performance LDHs powder is prepared by the hydrothermal method, and then the LDHs powder is compounded with sodium alginate to obtain solid - particle hydrogel balls. This hydrogel - ball adsorbent not only overcomes the difficulties of easy scattering of the powder and difficult recycling, but also solves the problem of low adsorption capacity of solid particles.

[0025] The hydrogel adsorbent prepared by the method of the present invention can greatly improve the treatment effect of the adsorbent on organic - pollutant wastewater. Through adsorption tests, the adsorption capacity for the organic congo red (CR) dye can reach more than 4400 mg / g, far higher than the capacities of the adsorbent materials developed at home and abroad at present. At the same time, the adsorbent material prepared by the present invention also has the characteristics of low cost, stable treatment, and high number of reusable times (≥8 times), and has broad application prospects in the treatment of industrial wastewater. Description of the Drawings

[0026] Figure 1 It is the appearance diagram of the adsorbents prepared in Comparative Example 1, Comparative Example 2, Example 1, and Comparative Example 3 of the present invention;

[0027] Figure 2 It is the physical diagram of the spherical six - component hydrotalcite - sodium alginate prepared in Example 1 of the present invention for adsorbing different concentrations of dye pigment (congo red);

[0028] Figure 3 It is the result diagram of the adsorption amount and removal rate of the adsorbents prepared in Example 1, Comparative Example 1 - 3 of the present invention;

[0029] Figure 4 Graph showing the results of the adsorbents prepared in Comparative Example 1, Comparative Example 2, and Example 1 of the present invention under the influence of adsorption time;

[0030] Figure 5 Graph showing the results of the adsorbents prepared in Comparative Example 1, Comparative Example 2, and Example 1 of the present invention under the influence of dosage;

[0031] Figure 6 Graph showing the results of the adsorbents prepared in Comparative Example 1, Comparative Example 2, and Example 1 of the present invention under the influence of adsorption temperature;

[0032] Figure 7 Graph showing the results of the adsorbents prepared in Comparative Example 1, Comparative Example 2, and Example 1 of the present invention under the influence of adsorption pH;

[0033] Figure 8 Graph showing the results of the number of cycles of the adsorbents prepared in Example 1, Comparative Examples 1 - 3 of the present invention. Detailed Embodiment

[0034] The following further describes the present invention in conjunction with the accompanying drawings and specific embodiments. It should be understood that the following embodiments are only further clarifications of the present invention and not limitations thereof. Unless otherwise specified, the reagents used in the following embodiments can be obtained from commercial channels.

[0035] Example 1

[0036] This example provides a spherical layered double hydroxide - sodium alginate adsorbent, and its preparation method includes the following steps:

[0037] (1) Accurately weigh 0.4958 g of zinc nitrate hexahydrate, 0.4183 g of manganese nitrate tetrahydrate, 0.4846 g of nickel nitrate hexahydrate, 0.4026 g of copper nitrate trihydrate, 0.6669 g of chromium nitrate nonahydrate, and 0.6252 g of aluminum nitrate nonahydrate in a beaker according to a molar ratio of 1:1:1:1:1:1. Add 12 mL of deionized water, and under stirring conditions, slowly add 1 mL of triethanolamine. After continuous stirring for 5 min, place it in a high - pressure reactor and react in an oven at 110°C for 2 h. Wash and dry the resulting product to obtain layered double hydroxide (LDHs) nanopowder;

[0038] (2) Dissolve 0.20 g of sodium alginate in 10 mL of deionized water, and fully stir it to uniformity at room temperature through a magnetic stirrer to obtain a sodium alginate aqueous solution; separately, ultrasonically disperse 0.2 g of the LDHs nanopowder obtained in step (1) in 10 mL of deionized water to obtain a LDHs dispersion after uniform dispersion; slowly drop the LDHs dispersion into the sodium alginate aqueous solution and stir at room temperature for 6 h to form a uniform mixed slurry;

[0039] (3) Use a 5 mL syringe to add the mixed slurry obtained in step (2) to a 0.1 mol / L calcium chloride aqueous solution for the formation of polymer beads, then cure in this solution for 12 h. After curing, wash twice with deionized water to obtain a spherical hexametal layered double hydroxide-sodium alginate hydrogel adsorbent, denoted as SA-ZnMnNiCuCrAl-LDHs, and store it in deionized water at room temperature for later use.

[0040] Example 2

[0041] This example provides a spherical layered double hydroxide-sodium alginate adsorbent, and its preparation method includes the following steps:

[0042] (1) Accurately weigh 0.4958 g of zinc nitrate hexahydrate, 0.4183 g of manganese nitrate tetrahydrate, 0.4846 g of nickel nitrate hexahydrate, 0.4026 g of copper nitrate trihydrate, 0.6669 g of chromium nitrate nonahydrate, and 0.6252 g of aluminum nitrate nonahydrate in a beaker according to a molar ratio of 1:1:1:1:1:1. Add 12 mL of deionized water, and slowly add 2 mL of triethanolamine under stirring conditions. After continuous stirring for 5 min, place it in a high-pressure reactor and react in an oven at 120 °C for 2 h. Wash and dry the resulting product to obtain layered double hydroxide (LDHs) nanopowder.

[0043] (2) Dissolve 0.22 g of sodium alginate in 10 mL of deionized water, and stir well at room temperature with a magnetic stirrer until uniform to obtain a sodium alginate aqueous solution; separately, ultrasonically disperse 0.22 g of the LDHs nanopowder obtained in step (1) in 10 mL of deionized water, and obtain an LDHs dispersion after uniform dispersion; slowly drop the LDHs dispersion into the sodium alginate aqueous solution, and stir at room temperature for 6 h to form a uniform mixed slurry.

[0044] (3) Use a 5 mL syringe to add the mixed slurry obtained in step (2) to a 0.2 mol / L calcium chloride aqueous solution for the formation of polymer beads, then cure in this solution for 12 h. After curing, wash twice with deionized water to obtain a spherical hexametal layered double hydroxide-sodium alginate hydrogel adsorbent, denoted as SA-ZnMnNiCuCrAl-LDHs, and store it in deionized water at room temperature for later use.

[0045] Example 3

[0046] This example provides a spherical layered double hydroxide-sodium alginate adsorbent, and its preparation method includes the following steps:

[0047] (1) Accurately weigh 0.4958 g of zinc nitrate hexahydrate, 0.4183 g of manganese nitrate tetrahydrate, 0.4846 g of nickel nitrate hexahydrate, 0.4026 g of copper nitrate trihydrate, 0.6669 g of chromium nitrate nonahydrate, and 0.6252 g of aluminum nitrate nonahydrate in a beaker according to a molar ratio of 1:1:1:1:1:1. Add 12 mL of deionized water, and slowly add 3 mL of triethanolamine under stirring conditions. After continuous stirring for 5 min, place it in a high-pressure reactor and react in an oven at 120 °C for 3 h. Wash and dry the resulting product to obtain layered double hydroxide (LDHs) nanometer powder;

[0048] (2) Dissolve 0.25 g of sodium alginate in 15 mL of deionized water, and stir thoroughly until uniform at room temperature by a magnetic stirrer to obtain an aqueous sodium alginate solution. Separately, ultrasonically disperse 0.25 g of the LDHs nanometer powder obtained in step (1) in 15 mL of deionized water, and obtain a LDHs dispersion after uniform dispersion. Slowly drop the LDHs dispersion into the aqueous sodium alginate solution, and stir at room temperature for 8 h to form a uniform mixed slurry;

[0049] (3) Use a 5 mL syringe to add the mixed slurry obtained in step (2) to a 0.2 mol / L calcium chloride aqueous solution for the formation of polymer beads, and then cure in this solution for 12 h. After curing, wash twice with deionized water to obtain a spherical hexa-component layered double hydroxide-sodium alginate hydrogel adsorbent, denoted as SA-ZnMnNiCuCrAl-LDHs, and store it in deionized water at room temperature for later use.

[0050] Comparative Example 1

[0051] This comparative example provides a pure sodium alginate bead adsorbent, and its preparation method is as follows:

[0052] Weigh 0.44 g of sodium alginate and dissolve it in 20 mL of deionized water, and stir thoroughly until uniform at room temperature by a magnetic stirrer to obtain a sodium alginate slurry. Use a 5 mL syringe to add the sodium alginate slurry to a 0.2 mol / L calcium chloride aqueous solution for the formation of polymer beads, and then cure in this solution for 12 h. After curing, wash twice with deionized water to obtain a pure sodium alginate bead adsorbent, denoted as SA, and store it in deionized water at room temperature for later use.

[0053] Comparative Example 2

[0054] This comparative example provides a ternary layered double hydroxide (LDHs, ZnMnNi)-sodium alginate bead adsorbent, and its preparation method is as follows:

[0055] (1) Weigh out 0.9916 g of zinc nitrate hexahydrate, 0.8367 g of manganese nitrate tetrahydrate, and 0.9693 g of nickel nitrate hexahydrate accurately according to a molar ratio of 1:1:1 in a beaker. Add 12 mL of deionized water, and slowly add 2 mL of triethanolamine under stirring conditions. After continuously stirring for 5 min, place it in a high-pressure reactor and react in an oven at 120 °C for 2 h. Wash and dry the resulting product to obtain LDHs nanometer powder;

[0056] (2) Dissolve 0.22 g of sodium alginate in 10 mL of deionized water, and stir well at room temperature by a magnetic stirrer until it is homogeneous to obtain an aqueous sodium alginate solution; separately, ultrasonically disperse 0.22 g of the LDHs nanometer powder obtained in step (1) in 10 mL of deionized water, and obtain an LDHs dispersion after uniform dispersion; slowly drop the LDHs dispersion into the aqueous sodium alginate solution, and stir at room temperature for 6 h to form a uniform mixed slurry;

[0057] (3) Use a 5 mL syringe to add the mixed slurry obtained in step (2) to a 0.2 mol / L calcium chloride aqueous solution for the formation of polymer beads. Then, after curing in this solution for 12 h, wash it twice with deionized water to obtain a spherical ternary hydrotalcite - sodium alginate hydrogel adsorbent, denoted as SA - ZnMnNi - LDHs, and store it in deionized water at room temperature for standby.

[0058] Comparative Example 3

[0059] This comparative example provides a hydrotalcite - like (LDHs) - sodium alginate spherical adsorbent, and its preparation process is basically the same as that of Example 2, except that in step (1), 2 mL of ethylenediamine is used instead of triethanolamine, and the remaining processes and parameters are the same as those of Example 2. The prepared adsorbent is denoted as SA - ZnMnNiCuCrAl - LDHs(EDA), and it is stored in deionized water at room temperature for standby.

[0060] Experimental Example 1

[0061] The appearance diagrams of the spherical adsorbents prepared in Comparative Example 1, Comparative Example 2, Example 2, and Comparative Example 3 of the present invention are as Figure 1 shown.

[0062] Figure 1 In the appearance diagrams, from left to right are the pure sodium alginate spherical adsorbent prepared in Comparative Example 1 (pure white spheres), the spherical ternary hydrotalcite - sodium alginate spherical adsorbent prepared in Comparative Example 2 (light green spheres), the spherical hexahydrotalcite - sodium alginate hydrogel adsorbent prepared in Example 2 of the present invention (dark green spheres), and the spherical hexahydrotalcite - sodium alginate spherical adsorbent prepared in Comparative Example 3 (black - brown spheres).

[0063] Further, the spherical hexavalent hydrotalcite-like material-sodium alginate prepared in Example 2 of the present invention was used for the adsorption of dye pigments (Congo red) at different concentrations, and the physical diagram of the adsorption is as Figure 2 shown.

[0064] Figure 2 From left to right are the adsorption effects of the adsorbent of Example 2 of the present invention on Congo red at 500 mg / L, 700 mg / L, 1000 mg / L, 2000 mg / L, and 4000 mg / L. As Figure 2 can be seen, the hexavalent hydrotalcite-like material-sodium alginate adsorbent of the present invention has good adsorption effects on Congo red at 500 - 4000 mg / L.

[0065] Test Example 2

[0066] The adsorption performance of the adsorbents prepared in Example 2 of the present invention and Comparative Examples 1 - 3 was tested in this test example. The test process was as follows: The adsorbents synthesized in the examples and comparative examples were used as adsorption materials to remove the anionic dye Congo red in water. And the following adsorption influencing factors were studied: the concentration value of the Congo red solution (0 - 8000 mg / L), the pH value of the Congo red solution (3 - 10), the dosage of the adsorbent (0 - 7 g / L), the adsorption time (0 - 10 h), and the temperature (20 - 35 °C).

[0067] The specific test process was as follows: In a 100 mL beaker, a certain amount of the adsorbent was stirred in 50 mL of the corresponding solution, and the adsorption experiment was carried out at the required concentration and solution pH. With the help of a magnetic stirrer, the beaker was stirred at a speed of 200 rpm for a specific time. The concentration of the supernatant was measured by an ultraviolet-visible spectrophotometer at a wavelength of λ = 500 nm (Congo red). The test results are as Figures 3 to 7 shown.

[0068] Among them, Figure 3 are the adsorption capacity and removal rate results of the pure sodium alginate beads (SA) of Comparative Example 1, the ternary hydrotalcite-like material beads (SA-ZnMnNi) of Comparative Example 2, the hexavalent hydrotalcite-like material beads (SA-ZnMnNiCuCrAl-LDHs(EDA)) of Comparative Example 3, and the hexavalent hydrotalcite-like material beads (SA-ZnMnNiCuCrAl-LDHs) of Example 2 of the present invention at different Congo red concentrations. As Figure 3It can be seen that the adsorption capacities of the pure sodium alginate beads in Comparative Example 1, the ternary LDHs (ZnMnNi)-sodium alginate beads in Comparative Example 2, and the LDHs-sodium alginate beads synthesized from ethylenediamine in Comparative Example 3 are 128, 680, and 1108 mg / g respectively, while the adsorption capacity of the hexavalent LDHs (ZnMnNiCuCrAl)-sodium alginate beads of the present invention is 4476 mg / g, indicating that the adsorption capacity has been greatly improved. This shows that the use of special LDHs in the present invention can prepare a hydrogel bead adsorbent with a high adsorption capacity.

[0069] Figure 4 Figure 4 shows the change of the removal rate with the adsorption time of the pure sodium alginate beads in Comparative Example 1, the SA-ZnMnNi-LDHs beads in Comparative Example 2, and the SA-ZnMnNiCuCrAl-LDHs beads in Example 2 of the present invention when the Congo red concentration is 2000 mg / L. Figure 5 Figure 5 shows the influence of different dosages of the pure sodium alginate beads in Comparative Example 1, the SA-ZnMnNi-LDHs beads in Comparative Example 2, and the SA-ZnMnNiCuCrAl-LDHs beads in Example 1 of the present invention on the removal effect when the Congo red concentration is 2000 mg / L. Figure 6 Figure 6 shows the effect diagram of the influence of temperature on the pure sodium alginate beads in Comparative Example 1, the SA-ZnMnNi-LDHs beads in Comparative Example 2, and the SA-ZnMnNiCuCrAl-LDHs beads in Example 1 of the present invention when the Congo red concentration is 2000 mg / L. Figure 7 Figure 7 shows the effect diagram of the influence of pH on the pure sodium alginate beads in Comparative Example 1, the SA-ZnMnNi-LDHs beads in Comparative Example 2, and the SA-ZnMnNiCuCrAl-LDHs beads in Example 1 of the present invention when the Congo red concentration is 2000 mg / L at different pH values. Figures 4 to 7 It can be seen that the removal rate of the hexavalent sodium alginate beads of the present invention is less affected by the adsorption time, dosage, temperature, and pH, showing a more long-lasting and stable removal effect.

[0070] Test Example 3

[0071] In this test example, the number of cycles of the adsorbents prepared in Example 2 of the present invention and Comparative Examples 1 to 3 was tested. The test process was as follows: Ethanol with a pH of 13 was used as the desorbing solution. In order to study the regeneration ability of each adsorbent, an adsorption-desorption process of 8 cycles was carried out. The results are as Figure 8 shown.

[0072] As Figure 8It can be seen that the adsorbent provided by the present invention can cyclically adsorb Congo red CR (100 mg / L) 8 times without destroying the hydrogel sphere structure. Moreover, the LDHs hydrogel sphere adsorbent in Example 2 of the present invention still has a stable removal rate of about 80% after 8 cycles of adsorption of 100 mg / L CR, which is significantly higher than the adsorption materials in Comparative Examples 1 to 3, indicating that the adsorbent of the present invention has excellent cyclic stability.

[0073] In summary, the preparation method of the spherical layered double hydroxide-sodium alginate adsorbent provided by the present invention first uses six metal salts as the raw materials for preparing LDHs, and triethanolamine as the base source, and further combines the hydrothermal method to prepare LDHs powder with high adsorption performance. Then, the LDHs powder is compounded with sodium alginate to obtain solid particle hydrogel spheres. The hydrogel sphere adsorbent not only overcomes the difficulties of easy scattering and difficult recycling of powders, but also solves the problem of low adsorption capacity of solid particles. Moreover, the hydrogel adsorbent prepared by the present invention can greatly improve the treatment effect of the adsorbent on organic pollutant wastewater. Through adsorption tests, the adsorption capacity for the organic CR dye can reach more than 4400 mg / g, far higher than the capacities of the adsorbent materials developed at home and abroad. At the same time, the adsorbent material prepared by the present invention also has the characteristics of low cost, stable treatment, and high reuse times, and has broad application prospects in the treatment of industrial wastewater.

Claims

1. A preparation method of a spherical hydrotalcite-like - sodium alginate adsorbent, characterized in that It includes the following steps: (1) Mix zinc nitrate, manganese nitrate, nickel nitrate, copper nitrate, chromium nitrate, aluminum nitrate with water, add triethanolamine under stirring conditions, continue stirring, then place it in a high-pressure reactor, carry out hydrothermal reaction at 100 - 120 °C for 2 - 4 h, wash and dry the generated product to obtain LDHs nano-powder; (2) Uniformly disperse the LDHs nano-powder obtained in step (1) in water to obtain an LDHs dispersion, then drop the LDHs dispersion into an aqueous sodium alginate solution, and stir evenly to obtain a mixed slurry; (3) Add the mixed slurry obtained in step (2) into an aqueous calcium chloride solution to form polymerized beads, then solidify and wash to obtain the spherical layered double hydroxide-sodium alginate adsorbent.

2. The preparation method of the spherical hydrotalcite-like - sodium alginate adsorbent according to claim 1, characterized in that, In step (1), the molar ratio of zinc nitrate, manganese nitrate, nickel nitrate, copper nitrate, chromium nitrate, aluminum nitrate is 1:1:1:1:1:1; in step (1), for every 1.6 - 1.7 mmol of zinc nitrate, the dosage of water is 10 - 14 mL, and the dosage of triethanolamine is 1 - 3 mL.

3. The preparation method of the spherical hydrotalcite-like compound-sodium alginate adsorbent according to claim 1, characterized in that, In step (2), in the LDHs dispersion, for every 0.2 g - 0.25 g of LDHs nano-powder, the dosage of water is 10 - 15 mL.

4. The preparation method of the spherical hydrotalcite-like - sodium alginate adsorbent according to claim 1, wherein, In step (2), in the aqueous sodium alginate solution, for every 0.2 g - 0.25 g of sodium alginate, the dosage of water is 10 - 15 mL.

5. The preparation method of the spherical hydrotalcite-like compound-sodium alginate adsorbent according to claim 1, wherein, In step (2), the stirring time is 6 - 8 h.

6. The preparation method of the spherical hydrotalcite-like alumina-sodium alginate adsorbent according to any one of claims 1 to 5, characterized in that, In step (3), the concentration of the aqueous calcium chloride solution is 0.1 - 0.2 mol / L.

7. The preparation method of the spherical hydrotalcite-like-alginate adsorbent according to any one of claims 1 to 5, characterized in that, In step (3), the solidification time is 10 - 15 h.

8. A spherical layered double hydroxide-sodium alginate adsorbent prepared by the preparation method according to any one of claims 1 - 7.

9. Use of the spherical hydrotalcite-like material-sodium alginate adsorbent according to claim 8, characterized in that, Application as an adsorption material for removing dye pollutants in water.

10. Use of the spherical hydrotalcite-like-alginate adsorbent according to claim 9, characterized in that, The dye pollutants are one or both of Congo Red and Methyl Orange.

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