A double 3D network encapsulated pickering emulsion type hydrogel, preparation method and application thereof

Abstract

This invention relates to the field of environmental functional materials, specifically to a dual 3D network-encapsulated Pickering emulsion hydrogel, its preparation method, and its applications. To develop a novel composite adsorbent material that integrates the large specific surface area of ​​Pickering emulsions with the high functional group density of hydrogels, is easily separable, and can perform both liquid-liquid extraction and solid-liquid adsorption for efficient magnesium-lithium separation, this invention stabilizes the polymerization of TBP / sulfonated kerosene Pickering emulsion using nano-silica particles to form a sodium alginate hydrogel. TBP / sulfonated kerosene Pickering emulsion droplets are encapsulated within the sodium alginate hydrogel, simplifying the complex "liquid-liquid extraction" process into a highly efficient "solid-liquid adsorption" process, achieving efficient capture of Li ions from brine.

Description

Technical Field

[0001] This invention relates to the field of environmental functional materials, specifically to a dual 3D network-encapsulated Pickering emulsion hydrogel, its preparation method, and its application. Background Technology

[0002] Global demand for lithium resources is experiencing explosive growth. Traditionally, lithium is extracted from ores, but this process is complex and energy-intensive. Currently, lithium extraction from salt lakes has become the main supply channel. However, my country's salt lake lithium resources generally have a high magnesium-to-lithium ratio, with high magnesium content. 2+ and Li + Lithium resources are difficult to extract from salt lake brines due to their similar hydration radius and chemical properties.

[0003] Existing methods for extracting lithium ions from brines with high magnesium-to-lithium ratios include solvent extraction and adsorption. Among these, adsorption is widely used due to its simple operation, low cost, and high efficiency. Compared with extraction, adsorption saves on salt field construction and shortens the production cycle, reduces equipment corrosion, and offers advantages such as high selectivity, fast separation speed, and recyclability. Therefore, there is an urgent need to develop a novel composite adsorbent material that integrates the large specific surface area of ​​Pickering emulsions with the high functional group density of hydrogels, is easy to separate, and can perform both liquid-liquid extraction and solid-liquid adsorption for efficient magnesium-to-lithium separation. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a dual 3D network-encapsulated Pickering emulsion hydrogel, which is a sodium alginate hydrogel polymerized from a Pickering emulsion stabilized by nano-silica particles, and its use in extracting lithium ions from brine.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] In a first aspect, the present invention provides a method for preparing a dual 3D network-encapsulated Pickering emulsion hydrogel, comprising the following steps:

[0007] Step 1: Mix deionized water and anhydrous ethanol, adjust the pH, add nano-SiO2, disperse by ultrasonication, and then add silane coupling agent 3-(methacryloyloxy)propyltrimethoxysilane (KH-570) to react. After the reaction is completed, dry the product to obtain modified nano-SiO2 particles.

[0008] Step 2: Add modified nano-SiO2 particles to sodium alginate solution and sonicate to obtain an aqueous phase; mix tributyl phosphate (TBP) with sulfonated kerosene to obtain an oil phase; disperse the oil phase and aqueous phase at high speed to obtain a Pickering emulsion.

[0009] Step 3: Pickering emulsion is dropped into CaCl2 solution and crosslinked to obtain the double 3D network encapsulated Pickering emulsion hydrogel.

[0010] Furthermore, in step 1, the ratio of deionized water to ethanol is 10:1, and the amount of silane coupling agent KH-570 is 15wt%~20wt% of nano-SiO2.

[0011] Furthermore, in step 1, the pH is adjusted to 3-4 with hydrochloric acid, the ultrasonic dispersion time is 2 hours, the reaction temperature is 70℃, and the reaction time is 4-5 hours.

[0012] Furthermore, in step 2, the concentration of the sodium alginate solution is 0.5wt%~1wt%, and the amount of modified nano-SiO2 particles is 1%~1.5% of the mass of the sodium alginate solution.

[0013] Furthermore, in step 2, the volume ratio of tributyl phosphate to sulfonated kerosene is 5:10 to 10:10.

[0014] Furthermore, in step 2, the volume ratio of the oil phase to the water phase is 5~8:10, the high-speed dispersion speed is 8000~12000 rpm, and the time is 1~4 min.

[0015] Furthermore, the concentration of the CaCl2 solution in step 3 is 5wt%-10wt%.

[0016] Furthermore, in step 3, the crosslinking temperature is 4°C and the time is 24 hours.

[0017] In a second aspect, the present invention provides a dual 3D network-encapsulated Pickering emulsion hydrogel prepared by the preparation method described in the first aspect.

[0018] Thirdly, this invention provides an application of a dual 3D network-encapsulated Pickering emulsion hydrogel in the extraction of lithium ions from brine.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] (1) This invention achieves highly selective solid-liquid extraction, solving the engineering challenges of solvent extraction. This invention encapsulates TBP / sulfonated kerosene Pickering emulsion droplets within a sodium alginate hydrogel, simplifying the complex liquid-liquid extraction process into a highly efficient solid-liquid adsorption process. It achieves selective lithium extraction and simple filtration separation, making the process green, safe, and easy to operate continuously.

[0021] (2) This invention generates a unique “sieving-extraction” synergistic mechanism, realizing the extraction of Li +Highly efficient capture of Li. Sodium alginate hydrogel network for Li + and Mg 2+ With certain differences in initial sieving and diffusion resistance, Li is preferentially allowed. + Diffusion into the gel interior; Li entering the gel interior + Upon encountering TBP molecules from Pickering emulsion droplets, TBP reacts with Li + (in Fe) 3+ In the presence of the complex, LiFeCl4·2TBP is formed.

[0022] (3) The Pickering emulsion formed numerous micron-scale "extraction sites" in the sodium alginate matrix, providing a suitable environment for the interaction of TBP and Li. + The reaction provides a large interfacial area, significantly reducing the time required for extraction equilibrium. The hydrophilic network of the hydrogel also promotes the extraction of Li in the aqueous phase. + The rapid migration overcomes the disadvantage of slow diffusion rate of traditional block adsorbents.

[0023] (4) After lithium adsorption saturation, efficient elution can be achieved using only dilute acid (such as dilute hydrochloric acid). The entire elution process is gentle, causing minimal damage to the sodium alginate network and Pickering emulsion structure. The material can be reused multiple times with its performance remaining essentially unchanged, demonstrating excellent economic efficiency. Attached Figure Description

[0024] Figure 1 This is a schematic diagram illustrating the preparation process of Pickering emulsion hydrogel according to an embodiment of the present invention;

[0025] Figure 2 This is a particle size distribution diagram of the Pickering emulsion hydrogel emulsion according to an embodiment of the present invention.

[0026] Figure 3 These are scanning electron microscope images of the Pickering emulsion hydrogel from an embodiment of the present invention;

[0027] Figure 4 The effect of lithium-magnesium separation in the Pickering emulsion hydrogel of this invention is shown in the embodiment of the present invention. Detailed Implementation

[0028] To further illustrate the technical solution of the present invention, the present invention will be further described below through embodiments.

[0029] Example 1

[0030] like Figure 1 As shown, a method for preparing a dual 3D network-encapsulated Pickering emulsion hydrogel includes the following steps:

[0031] (1) Modification of nano-SiO2 particles: Deionized water and anhydrous ethanol were mixed and the pH was adjusted to 3-4 with hydrochloric acid. Then 0.6g of nano-SiO2 was added, and after ultrasonic dispersion for 2h, it was poured into a flask. Silane coupling agent KH-570 was added at 20wt% of the amount of nano-SiO2, and the reaction was carried out at 70℃ for 4h. The product was then dried.

[0032] (2) Preparation of TBP / sulfonated kerosene Pickering emulsion: 0.08 g of sodium alginate was dissolved in 10 mL of water, and 0.15 g of modified nano-SiO2 particles were added and ultrasonically vibrated to obtain an aqueous phase. Tributyl phosphate (TBP) and sulfonated kerosene were mixed in a certain proportion to obtain an oil phase. The oil phase and aqueous phase were dispersed at a volume ratio of 8:10 at a high speed of 8000 rpm for 3 min to obtain the TBP / sulfonated kerosene Pickering emulsion.

[0033] (3) Crosslinking: Pickering emulsion was dropped into 5wt% CaCl2 solution and crosslinked at 4℃ for 24 hours to obtain Pickering emulsion hydrogel.

[0034] Example 2

[0035] A method for preparing a dual 3D network-encapsulated Pickering emulsion hydrogel includes the following steps:

[0036] (1) Modification of nano-SiO2 particles: Deionized water and anhydrous ethanol were mixed and the pH was adjusted to 3-4 with hydrochloric acid. 0.6g of nano-SiO2 was added and ultrasonically dispersed for 2h, then poured into a flask. 20wt% of silane coupling agent KH-570 was added, and the mixture was reacted at 70℃ for 5h, after which the product was dried.

[0037] (2) Preparation of TBP / sulfonated kerosene Pickering emulsion: 0.08 g of sodium alginate was dissolved in 10 mL of water, and 0.1 g of modified nano-SiO2 particles were added and ultrasonically vibrated to obtain an aqueous phase. Tributyl phosphate (TBP) and sulfonated kerosene were mixed in a certain proportion to obtain an oil phase. The oil phase and aqueous phase were dispersed at a volume ratio of 5:10 at a high speed of 8000 rpm for 2 min to obtain the TBP / sulfonated kerosene Pickering emulsion.

[0038] (3) Crosslinking: Pickering emulsion was dropped into 5wt% CaCl2 solution and crosslinked at 4℃ for 24 hours to obtain Pickering emulsion hydrogel.

[0039] Example 3

[0040] A method for preparing a dual 3D network-encapsulated Pickering emulsion hydrogel includes the following steps:

[0041] (1) Modification of nano-SiO2 particles: Deionized water and anhydrous ethanol were mixed and the pH was adjusted to 3-4 with hydrochloric acid. Then 0.6g of nano-SiO2 was added, and after ultrasonic dispersion for 2h, it was poured into a flask. Silane coupling agent KH-570 was added at 20wt% of the amount of nano-SiO2, and the reaction was carried out at 70℃ for 4h. The product was then dried.

[0042] (2) Preparation of TBP / sulfonated kerosene Pickering emulsion: 0.08 g of sodium alginate was dissolved in 10 mL of water, and 0.15 g of modified nano-SiO2 particles were added and ultrasonically vibrated to obtain an aqueous phase. Tributyl phosphate (TBP) and sulfonated kerosene were mixed in a certain proportion to obtain an oil phase. The oil phase and aqueous phase were dispersed at a volume ratio of 5:10 at a high speed of 8000 rpm for 4 min to obtain the TBP / sulfonated kerosene Pickering emulsion.

[0043] (3) Crosslinking: Pickering emulsion was dropped into 5wt% CaCl2 solution and crosslinked at 4℃ for 24 hours to obtain Pickering emulsion hydrogel.

[0044] Example 4

[0045] A method for preparing a dual 3D network-encapsulated Pickering emulsion hydrogel includes the following steps:

[0046] (1) Modification of nano-SiO2 particles: Deionized water and anhydrous ethanol were mixed and the pH was adjusted to 3-4 with hydrochloric acid. Then 0.6g of nano-SiO2 was added, and after ultrasonic dispersion for 2h, it was poured into a flask. Silane coupling agent KH-570 was added at 20wt% of the amount of nano-SiO2, and the reaction was carried out at 70℃ for 4h. The product was then dried.

[0047] (2) Preparation of TBP / sulfonated kerosene Pickering emulsion: 0.05 g of sodium alginate was dissolved in 10 mL of water, and 0.1 g of modified nano-SiO2 particles were added and ultrasonically vibrated to obtain an aqueous phase. Tributyl phosphate (TBP) and sulfonated kerosene were mixed in a certain proportion to obtain an oil phase. The oil phase and aqueous phase were dispersed at a volume ratio of 5:10 at a high speed of 8000 rpm for 2 min to obtain the TBP / sulfonated kerosene Pickering emulsion.

[0048] (3) Crosslinking: Pickering emulsion was dropped into 5wt% CaCl2 solution and crosslinked at 4℃ for 24 hours to obtain Pickering emulsion hydrogel.

[0049] Comparative Example 1

[0050] A method for preparing a sodium alginate hydrogel material includes the following steps:

[0051] (1) Preparation of sodium alginate solution: Take an appropriate amount of sodium alginate and add it to water to dissolve it completely.

[0052] (2) Crosslinking: Sodium alginate solution was added dropwise to CaCl2 solution and crosslinked at 4℃ for 24 hours to obtain sodium alginate hydrogel.

[0053] The effects of the hydrogels in Examples 1-4 were analyzed. The stability of the Pickering emulsions in Examples 1-4 was observed (e.g., ...). Figure 2 ), hydrogel scanning electron microscopy (e.g.) Figure 3 The lithium extraction effect of hydrogels in Examples 1-4 and the comparative examples under the same conditions (e.g.) Figure 4 ).

[0054] Depend on Figure 2 It can be seen that all examples 1-4 can form emulsions. The emulsion of example 1 has balanced performance, with nearly spherical droplets, relatively uniform particle size distribution, no obvious agglomeration, and good overall stability. The droplet size of example 2 has a large range, with a large difference in particle size between large and small droplets, resulting in a wide particle size distribution and insufficient uniformity. The emulsion of example 3 has the best overall performance, with the smallest droplet size and highly uniform particle size distribution. The droplets are densely arranged with clear boundaries, and there is no obvious large droplet or agglomeration phenomenon. This indicates that the emulsification efficiency is the highest under this condition, the adsorption of solid particles at the oil-water interface is sufficient, a stable interfacial film is formed, and the emulsion has the best dispersibility and storage stability. The emulsion of example 4 has the worst stability, with significantly larger droplet size and obvious deformation and fusion trends. The droplet boundaries are blurred and the background is turbid. This indicates that the interfacial stability of solid particles is insufficient under this condition, and the droplets undergo severe agglomeration, posing a risk of demulsification.

[0055] Depend on Figure 3It can be seen that all of Examples 1 to 4 can form a three-dimensional network structure. Example 1 exhibits a regular and orderly honeycomb-like open-pore structure with continuous and intact pore walls of uniform thickness and excellent pore connectivity. There is no obvious structural collapse or defect, indicating that the hydrogel network formed under these conditions has uniform cross-linking and good mechanical support, providing ideal channels for ion transport and mass diffusion. Example 2 shows significant coarsening and deformation of the pore structure, with a significantly increased and unevenly distributed pore size. Some pore walls have fused and wrinkled, and the integrity of the framework has decreased, reflecting insufficient cross-linking or abnormal phase separation behavior of the gel network under these conditions, resulting in weakened structural stability. Example 3 has the most dense and uniform pore structure, with thin and continuous pore walls, high porosity, and good connectivity. Simultaneously, the framework surface is distributed with fine nanoscale rough structures, indicating that the gel has the highest pore-forming efficiency and the finest network structure under these conditions, potentially achieving superior adsorption and separation performance. Example 4 shows large-area collapse and fusion of the pores, forming irregular large-sized pores with rough pore walls and numerous fractures and damages. The continuity of the framework is completely destroyed, indicating poor cross-linking effect of the gel network under these conditions, and extremely poor mechanical stability and structural integrity.

[0056] Depend on Figure 4 It can be seen that: the Li in the comparative sample + The extraction rate was 32.6%, Mg 2+ With an extraction rate as high as 29.1% and a Li / Mg separation coefficient of only about 1.18, it indicates extremely poor selectivity for Li⁺ and cannot effectively separate Li⁺ from Mg. 2+ In Example 1, the Li⁺ extraction rate was increased to 35.5%, and the Mg extraction rate was... 2+ The extraction rate was 8.2%, the separation coefficient increased to 6.13, and the selectivity was improved compared to the comparative example; the Li⁺ extraction rate in Example 2 was 33.6%, and the Mg extraction rate was... 2+ The extraction rate was 8.6%, and the separation coefficient was 5.34. Although the selectivity was still much better than the comparative example, it was slightly lower than that of Example 1. Example 3 showed the best overall performance, with a Li⁺ extraction rate of 37.8% and a Mg extraction rate of 5.34%. 2+ The extraction rate was only 8.6%, while the separation coefficient was as high as 6.42, achieving a synergistic improvement in both high Li⁺ extraction rate and high Li / Mg selectivity; the Li⁺ extraction rate in Example 4 was 32.8%, and the Mg... 2+ The extraction rate was 8.5%, and the separation coefficient was 5.08. The performance was better than the comparative example but weaker than Examples 1, 2, and 3.

[0057] The foregoing has shown and described the main features and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0058] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing a double 3D network-encapsulated Pickering emulsion hydrogel, characterized in that, Includes the following steps: Step 1: Mix deionized water and anhydrous ethanol, adjust the pH, add nano-SiO2, disperse by ultrasonication, add silane coupling agent KH-570 to react, and dry the product after the reaction to obtain modified nano-SiO2 particles. Step 2: Add modified nano-SiO2 particles to sodium alginate solution and sonicate to obtain an aqueous phase; mix tributyl phosphate with sulfonated kerosene to obtain an oil phase; disperse the oil phase and aqueous phase at high speed to obtain a Pickering emulsion. Step 3: Pickering emulsion is dropped into CaCl2 solution and crosslinked to obtain the double 3D network encapsulated Pickering emulsion hydrogel.

2. The method for preparing a dual 3D network-encapsulated Pickering emulsion hydrogel according to claim 1, characterized in that, In step 1, the ratio of deionized water to ethanol is 10:1, and the amount of silane coupling agent KH-570 is 15wt%~20wt% of nano-SiO2.

3. The method for preparing a dual 3D network-encapsulated Pickering emulsion hydrogel according to claim 1, characterized in that, In step 1, the pH is adjusted to 3-4 with hydrochloric acid, the ultrasonic dispersion time is 2 hours, the reaction temperature is 70℃, and the reaction time is 4-5 hours.

4. The method for preparing a dual 3D network-encapsulated Pickering emulsion hydrogel according to claim 1, characterized in that, In step 2, the concentration of sodium alginate solution is 0.5wt%~1wt%, and the amount of modified nano-SiO2 particles used is 1wt%~1.5wt% of sodium alginate solution.

5. The method for preparing a dual 3D network-encapsulated Pickering emulsion hydrogel according to claim 1, characterized in that, In step 2, the volume ratio of tributyl phosphate to sulfonated kerosene is 5:10-10:

10.

6. The method for preparing a dual 3D network-encapsulated Pickering emulsion hydrogel according to claim 1, characterized in that, In step 2, the volume ratio of oil phase to water phase is 5~8:10, the high-speed dispersion speed is 8000~12000 rpm, and the time is 1~4 min.

7. The method for preparing a dual 3D network-encapsulated Pickering emulsion hydrogel according to claim 1, characterized in that, In step 3, the concentration of the CaCl2 solution is 5wt%-10wt%.

8. The method for preparing a dual 3D network-encapsulated Pickering emulsion hydrogel according to claim 1, characterized in that, In step 3, the crosslinking temperature is 4°C and the time is 24 hours.

9. A double 3D network-encapsulated Pickering emulsion hydrogel prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the dual 3D network encapsulated Pickering emulsion hydrogel according to claim 9, characterized in that, Applications of lithium ion extraction from brine.

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