A porous hydrogel microsphere and a preparation method and application thereof

Abstract

The present application relates to the technical field of biomaterials, and particularly relates to a porous hydrogel microsphere, a preparation method and application thereof. The method comprises the following steps: dissolving sodium alginate and polyvinyl alcohol in water to obtain a multi-component polymer aqueous solution; adding the multi-component polymer aqueous solution into an oil phase to disperse the multi-component polymer aqueous solution into droplets to form a water-in-oil emulsion; and mixing the water-in-oil emulsion and calcium chloride to cause ion cross-linking reaction of sodium alginate in the droplets, wherein the multi-component polymer in the droplets undergoes phase separation structure evolution and is in-situ fixed under the cross-linking effect to obtain the porous hydrogel microsphere. The present application provides a preparation method of the porous hydrogel microsphere with controllable structure and simple process, and realizes in-situ construction of the internal connected porous structure of the microsphere in the emulsification and cross-linking process, thereby overcoming the problems of dense internal structure, difficult connection of the pores, complex preparation process and insufficient structural stability in the prior art.

Description

Technical Field

[0001] This invention relates to the field of biomaterials technology, specifically to a porous hydrogel microsphere, its preparation method, and its application. Background Technology

[0002] Hydrogel microspheres, due to their excellent hydrophilicity, tunable network structure, and high specific surface area, have broad application prospects in adsorption separation, drug delivery, catalyst carriers, and environmental remediation. In particular, hydrogel microspheres based on natural polymers have attracted widespread attention due to their good biocompatibility, wide availability of raw materials, and mild preparation conditions. Among them, sodium alginate, which can undergo rapid ionic cross-linking under the action of divalent metal ions to form a stable three-dimensional network structure, is one of the more mature material systems currently used in the preparation of hydrogel microspheres.

[0003] In existing technologies, hydrogel microspheres are typically prepared via droplet preparation, emulsion crosslinking, or spraying. Among these, emulsion crosslinking is widely used due to its simplicity, adjustable particle size, and ease of large-scale production. However, in emulsion crosslinking systems, the limited size of the aqueous droplets and the rapid crosslinking reaction rate often lead to the rapid solidification of the polymer network within a short time. This results in a dense internal structure with low porosity and a lack of effective connectivity between internal channels in the hydrogel microspheres. This dense structure restricts the diffusion and mass transfer of solutes within the microspheres, thus affecting their overall performance in applications such as adsorption and reaction.

[0004] To improve the internal structure of hydrogel microspheres, existing research has proposed various methods for introducing pores, such as introducing solid or soluble sacrificial templates, gas foaming, lyophilization, and solvent displacement. While these methods can increase the porosity of microspheres, they typically involve complex preparation processes, demanding equipment and operating conditions, and cumbersome post-processing steps. Furthermore, these methods can easily damage the original spherical structure and mechanical stability of the microspheres during template removal or drying, and the controllability and reproducibility of the resulting pore structure are limited, making it difficult to meet the requirements of large-scale and stable applications. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a porous hydrogel microsphere, its preparation method, and its applications. This invention uses sodium alginate and polyvinyl alcohol as microsphere building materials. The two are dissolved together to form a multi-component polymer aqueous solution, which is then dispersed in an oil phase to form an emulsion. Subsequently, a calcium ion crosslinking agent is introduced to induce an ion crosslinking reaction in sodium alginate, ultimately yielding porous hydrogel microspheres with a three-dimensional continuous interconnected pore network. This invention utilizes the phase separation behavior of the multi-component polymer system during the emulsification and crosslinking process to achieve in-situ construction and fixation of the porous structure, overcoming the problems of dense internal microsphere structures, difficult pore connectivity, reliance on templates, or complex post-processing in existing technologies. Simultaneously, it eliminates the need for sacrificing templates, freeze-drying, or solvent replacement post-processing methods, simplifying the preparation process while maintaining the stability of the porous structure and microsphere morphology, significantly improving the internal mass transfer performance and functional application efficiency of the microspheres.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first objective of this invention is to provide a method for preparing porous hydrogel microspheres, comprising the following steps: S1. Sodium alginate and polyvinyl alcohol are dissolved together in water to obtain a multi-component polymer aqueous solution. This invention selects sodium alginate and polyvinyl alcohol as microsphere building materials, mainly based on their good water solubility, biocompatibility, and high compatibility with emulsion-based microsphere formation processes. Sodium alginate can rapidly undergo ionic crosslinking with divalent metal ions under mild conditions, achieving instantaneous solidification of the droplet morphology, which is beneficial for obtaining a regular microsphere structure. Polyvinyl alcohol has good film-forming properties and flexibility, which can improve the structural integrity and stability of porous hydrogel microspheres. Simultaneously, due to the limited compatibility of the two microsphere building materials in terms of molecular structure and interaction, microscale phase separation easily occurs within the confined droplet space. This phase-separated structure is solidified during the crosslinking process, thus providing an intrinsic driving force for the in-situ formation of the porous structure inside the porous hydrogel microspheres.

[0007] S2. The multi-component polymer aqueous solution is added dropwise to the oil phase, which is a mixture of continuous liquid paraffin and an emulsifier, to disperse the multi-component polymer aqueous solution into droplets, forming a water-in-oil emulsion. The selection of the emulsifier is based on its hydrophilic-hydrophobic balance (HLB) value. Any emulsifier suitable for preparing water-in-oil emulsions can be used; in this invention, sorbitan monooleate (Span-80) is preferred.

[0008] S3. A water-in-oil emulsion and calcium chloride are mixed to induce an ionic crosslinking reaction of sodium alginate within the droplets. During this reaction, the multi-component polymers undergo phase separation and structural evolution within the droplets and are subsequently fixed in situ by the crosslinking process, resulting in porous hydrogel microspheres. After the emulsion droplets form, sodium alginate and polyvinyl alcohol undergo continuous chain rearrangement and spatial distribution regulation within the confined droplet space. Due to differences in molecular structure, chain rigidity, and interaction ability with crosslinking ions, when divalent metal ions diffuse from the outer phase into the droplet interior, sodium alginate preferentially participates in ionic crosslinking and forms a locally dense network, thus limiting its further migration. Polyvinyl alcohol, due to its weaker crosslinking response, is mainly retained in the undensified region. As the crosslinking process progresses, the aforementioned non-uniform network structure is gradually solidified and stably preserved, ultimately forming a heterogeneous network with multi-level structural characteristics within the microspheres, thereby endowing the microspheres with excellent structural stability and mass transfer performance.

[0009] When ionic crosslinking occurs, the rapid formation of crosslinking points significantly increases the rigidity of the local network structure, thereby inhibiting further diffusion and reconstruction of chain segments. As the degree of crosslinking continues to increase, the system gradually transforms from a flowable state into a stable three-dimensional network structure, directly "locking" the spatial distribution and structural features formed at that time in their original positions without undergoing additional morphology control or post-processing. This process is known as in-situ fixation of the structure under crosslinking.

[0010] This invention selects calcium chloride as the crosslinking medium, mainly because it is highly soluble in the aqueous phase, can stably release divalent calcium ions, and can undergo rapid ionic crosslinking with the carboxyl groups on the sodium alginate molecular chain under mild conditions, thereby achieving instant solidification of the droplet structure. At the same time, calcium chloride is widely available, low in cost, and has good reaction controllability, and will not introduce organic crosslinking residues, making it suitable for the stable construction of microsphere structures in emulsion systems.

[0011] Preferably, in the multi-component polymer aqueous solution, the mass percentage of sodium alginate is 1% to 3% and the mass percentage of polyvinyl alcohol is 3% to 7%.

[0012] Preferably, the volume ratio of emulsifier to continuous phase liquid paraffin is 1:15~25.

[0013] Preferably, the volume ratio of the multi-component polymer aqueous solution to the oil phase is 1:5~15.

[0014] Preferably, the mass ratio of calcium chloride to sodium alginate is 1:0.02~0.08.

[0015] Preferably, the conditions for the ionic crosslinking reaction are: stirring at 30℃~35℃ for 2h at a stirring rate of 200rpm~400rpm.

[0016] The second objective of this invention is to provide porous hydrogel microspheres prepared by the above-described method, wherein the porous hydrogel microspheres are spherical and have a three-dimensional continuous network of pores inside.

[0017] A third objective of this invention is to provide the application of the above-mentioned porous hydrogel microspheres in the preparation of dye adsorbents.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention provides a method for preparing porous hydrogel microspheres, comprising the following steps: dissolving sodium alginate and polyvinyl alcohol together in water to obtain a multi-component polymer aqueous solution; adding the multi-component polymer aqueous solution dropwise to an oil phase composed of a continuous phase of liquid paraffin and an emulsifier, thereby dispersing the multi-component polymer aqueous solution into droplets to form a water-in-oil emulsion; mixing the water-in-oil emulsion with calcium chloride to cause the sodium alginate in the droplets to undergo an ionic crosslinking reaction. During the ionic crosslinking reaction, the multi-component polymer undergoes phase separation and structural evolution inside the droplets and is fixed in situ under the crosslinking action to obtain porous hydrogel microspheres. This invention utilizes the phase separation behavior of a multi-component polymer system during emulsification and crosslinking to achieve in-situ construction and fixation of porous structures, overcoming the problems of dense internal structures, difficult-to-connect pores, reliance on templates or complex post-processing in existing technologies. At the same time, it eliminates the need for post-processing methods such as templates, freeze-drying, or solvent replacement, simplifying the preparation process while taking into account the stability of porous structures and microsphere morphology, significantly improving the internal mass transfer performance and functional application efficiency of microspheres.

[0019] First, it enables the in-situ construction of interconnected porous structures within porous hydrogel microspheres: During the emulsification and crosslinking process, the present invention achieves the simultaneous formation and fixation of porous structures within the microspheres without relying on post-processing methods such as sacrificial templates, freeze-drying, or solvent replacement. This allows for the acquisition of porous hydrogel microspheres with continuously interconnected pores, effectively overcoming the problems of dense internal structures and difficult-to-connect pores in existing technologies.

[0020] Secondly, the preparation process is simple, the operating conditions are mild, and it is suitable for large-scale application: This invention achieves the construction of porous structures by introducing the composite effect of a multi-component polymer system on the basis of conventional emulsification crosslinking process. The preparation process is simple, with few steps, low requirements for equipment and operating conditions, and has good process stability and scale-up potential.

[0021] Third, the controllability and repeatability of the pore structure are significantly improved: by adjusting the composition ratio and process parameters of the multi-component polymer (such as stirring speed, crosslinking ion concentration, etc.), the stable formation and precise control of the internal pore structure of the porous hydrogel microspheres can be achieved. The resulting porous structure has good batch repeatability, which is conducive to the consistent control of product quality.

[0022] Fourth, it balances porous structure with microsphere morphology stability: The porous hydrogel microspheres obtained by this invention maintain good spherical integrity and structural stability while introducing an internal porous structure, avoiding the problems of structural collapse and morphological damage caused by template removal or post-processing in traditional porousing methods.

[0023] Fifth, it significantly improves the internal mass transfer and functional performance of microspheres: The introduction of the interconnected porous structure in this invention effectively shortens the diffusion path of solutes inside the porous hydrogel microspheres, improves the mass transfer efficiency, and thus helps to improve the overall performance of porous hydrogel microspheres in adsorption and related functional applications.

[0024] Sixth, the material system is highly versatile and has a wide range of applications: the preparation method of this invention is not limited to the sodium alginate / polyvinyl alcohol system, but can also be applied to water-soluble polymer systems such as polyethyleneimine / polyvinyl alcohol system and polyethyleneimine / sodium alginate system. By reasonably adjusting the polymer type and parameter settings, it can be extended to a variety of hydrogel microsphere systems, and has good versatility and application expansion potential.

[0025] 2. Existing literature reports that sodium alginate / polyvinyl alcohol composite systems typically employ a natural dropwise addition method to prepare cross-linked microspheres. This approach focuses on optimizing sphere formation and mechanical properties by controlling the polymer ratio and cross-linking time, resulting in microspheres with a dense internal structure. In contrast, this invention couples the emulsification sphere formation process with the ionic cross-linking process. Within the confined space of the water-in-oil emulsion droplets, the phase separation behavior of sodium alginate and polyvinyl alcohol is actively controlled. Utilizing the rapid curing characteristics of the ionic cross-linking reaction, the transiently evolving phase-separated structure is fixed in situ. This allows for the one-step construction of porous hydrogel microspheres with a three-dimensional interconnected pore network without templates, solvent replacement, or post-treatment. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the preparation process of the porous hydrogel microspheres of the present invention.

[0027] Figure 2 The images show SEM images of the porous hydrogel microspheres of Example 1 and the hydrogel microspheres of Comparative Example 1. (a), (b), and (c) are SEM images of the hydrogel microspheres of Comparative Example 1, and (d), (e), and (f) are SEM images of the porous hydrogel microspheres of Example 1. The scale bars for (a) and (d) are 50 μm, for (b) and (e) they are 4 μm, and for (c) and (f) they are 1 μm.

[0028] Figure 3The images show the infrared spectrum, Raman spectrum, and X-ray photoelectron spectrum of SA, PVA, porous hydrogel microspheres of Example 1, and hydrogel microspheres of Comparative Example 1. Specifically, a is the infrared spectrum, b is the Raman spectrum, c is the full X-ray photoelectron spectrum of SA, PVA, porous hydrogel microspheres of Example 1, and hydrogel microspheres of Comparative Example 1, d is the C spectrum, e is the O spectrum, and f is the Ca spectrum.

[0029] Figure 4 The figures show the nitrogen adsorption-desorption isotherms, pore size distribution curves, thermogravimetric curves, and differential scanning calorimetry curves for the porous hydrogel microspheres of Example 1 and Comparative Example 1. In particular, a is the nitrogen adsorption-desorption isotherm of the hydrogel microspheres of Comparative Example 1, b is the nitrogen adsorption-desorption isotherm of the porous hydrogel microspheres of Example 1, the insets in a and b are pore size distribution curves, c is the thermogravimetric curve, and d is the differential scanning calorimetry curve.

[0030] Figure 5 The adsorption capacity and removal rate of methylene blue by porous hydrogel microspheres under different influencing factors are shown in Figure 1. Here, a is the pH value, b is the amount of adsorbent, c is the temperature, d is the contact time, and e is the initial concentration of methylene blue. Detailed Implementation

[0031] The technical solution of the present invention will be clearly and completely described below with reference to the data in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0032] It should be noted that the technical terms used in this invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased on the market or prepared by existing methods.

[0033] The key technical point of this invention lies not in the selection of a single material, but in achieving the in-situ construction and stable fixation of the interconnected porous structure within porous hydrogel microspheres through the composite action of multiple polymer components in an emulsion-crosslinked restricted system. Specifically, this is mainly reflected in the following aspects:

[0034] First, the synergistic design of multi-component polymer systems. This invention introduces sodium alginate and polyvinyl alcohol into an aqueous system, utilizing the difference in their interactions at certain concentration ratios to induce structural evolution of the multi-component polymer within the droplets, providing the foundation for the formation of porous structures.

[0035] Secondly, the in-situ formation and fixation of the pore structure during the emulsion crosslinking process. In the emulsion droplet environment, by controlling the introduction method of crosslinking ions and the crosslinking conditions, the structural evolution process and the crosslinking curing process are coupled with each other, thereby fixing the formed internal porous structure in situ during the microsphere molding process and avoiding damage to the structure by subsequent processing.

[0036] Third, the invention employs a porous structure strategy that eliminates the need for templates and complex post-processing. Instead of relying on traditional porous structures involving sacrificial templates, lyophilization, or solvent replacement, the invention directly achieves porous structure formation during the preparation process, significantly simplifying the preparation procedure.

[0037] Fourth, it balances the porous structure with the morphological stability of the porous hydrogel microspheres. Through reasonable system design and process parameter control (raw material selection, cross-linking reaction conditions), the obtained porous hydrogel microspheres maintain good spherical integrity and structural stability while having an internal interconnected pore structure.

[0038] To enable those skilled in the art to more clearly understand the technical solution of the present invention, the following will provide a detailed description in conjunction with specific embodiments: Example 1 A method for preparing porous hydrogel microspheres, the preparation flow chart is as follows: Figure 1 As shown, it includes the following steps: S1. Dissolve 0.2g sodium alginate and 0.5g polyvinyl alcohol together in 10mL deionized water and stir thoroughly at room temperature to obtain a homogeneous multi-component polymer aqueous solution. Mix 2mL of Span-80 with 40mL of liquid paraffin and stir thoroughly at 40℃ and 800rpm to obtain an oil phase. Then, take 4mL of the multi-component polymer aqueous solution and add it dropwise to the oil phase. Under stirring conditions, disperse the multi-component polymer aqueous solution into uniform droplets to form a water-in-oil emulsion.

[0039] S2. Under continuous stirring, add 2g of calcium chloride crosslinking solution dissolved in 2mL of water to the water-in-oil emulsion, and stir at 300rpm for 2h at 30℃ to allow the droplets to undergo crosslinking and solidification reaction to form hydrogel microspheres; after crosslinking is completed, wash and separate the oil phase and unreacted substances to obtain porous hydrogel microspheres.

[0040] Example 2 A method for preparing porous hydrogel microspheres includes the following steps: S1. Dissolve 0.1g sodium alginate and 0.3g polyvinyl alcohol together in 10mL deionized water and stir thoroughly at room temperature to obtain a homogeneous multi-component polymer aqueous solution. Mix 2mL Span-80 with 30mL liquid paraffin and stir thoroughly at 40℃ and 800rpm to obtain an oil phase. Then, take 4mL of the multi-component polymer aqueous solution and add it dropwise to the oil phase. Under stirring conditions, disperse the multi-component polymer aqueous solution into uniform droplets to form a water-in-oil emulsion.

[0041] S2. Under continuous stirring, add 2g of calcium chloride crosslinking solution dissolved in 2mL of water to the water-in-oil emulsion, and stir at 200rpm for 2h at 30℃ to allow the droplets to undergo crosslinking and solidification reaction to form hydrogel microspheres. After crosslinking is completed, the microspheres are washed and separated to remove the oil phase and unreacted substances, and porous hydrogel microspheres are obtained.

[0042] Example 3 A method for preparing porous hydrogel microspheres includes the following steps: S1. Dissolve 0.3g sodium alginate and 0.7g polyvinyl alcohol together in 10mL deionized water and stir thoroughly at room temperature to obtain a homogeneous multi-component polymer aqueous solution. Mix 2mL of Span-80 with 50mL of liquid paraffin and stir thoroughly at 40℃ and 800rpm to obtain an oil phase. Then, take 4mL of the multi-component polymer aqueous solution and add it dropwise to the oil phase. Under stirring conditions, disperse the multi-component polymer aqueous solution into uniform droplets to form a water-in-oil emulsion.

[0043] S2. Under continuous stirring, add 2g of calcium chloride crosslinking solution dissolved in 2mL of water to the water-in-oil emulsion, and stir at 35℃ and 400rpm for 2h to allow the droplets to undergo crosslinking and solidification reaction to form hydrogel microspheres; after crosslinking is completed, wash and separate the oil phase and unreacted substances to obtain porous hydrogel microspheres.

[0044] Comparative Example 1 A method for preparing hydrogel microspheres is the same as that in Example 1, except that sodium alginate is used as the aqueous polymer to obtain hydrogel microspheres.

[0045] a. Structure and Representation: like Figure 2As shown, the porous hydrogel microspheres prepared in this invention possess a complete spherical structure, with an internal porous network induced by the structural evolution of multi-component polymers. This pore structure is continuously interconnected and uniformly distributed within the microspheres, significantly promoting the diffusion and mass transfer of solutes within the microspheres. In contrast, the hydrogel microspheres of Comparative Example 1 have a relatively dense internal structure with a limited number of pores and poor pore connectivity; while the porous hydrogel microspheres prepared in Example 1 exhibit a clear porous morphology with uniform pore distribution and good connectivity.

[0046] The above comparison results fully demonstrate that the multi-component polymer system and its preparation method used in this invention can effectively regulate the internal structure of hydrogel microspheres, thereby providing a structural basis for improving their performance in functional applications such as adsorption and mass transfer.

[0047] Compared with hydrogel microspheres prepared by a single polymer system, the porous hydrogel microspheres prepared by this invention have a significantly increased number of internal pores and significantly improved pore connectivity. At the same time, while maintaining good spherical integrity, the internal structure of the hydrogel microspheres can be precisely controlled.

[0048] The porous hydrogel microspheres of Example 1 were characterized by infrared spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. Figure 3 As shown in the figure. The results indicate that the porous hydrogel microspheres prepared in this invention simultaneously contain characteristic functional group signals of sodium alginate and polyvinyl alcohol, indicating that sodium alginate and polyvinyl alcohol were successfully introduced and coexist in the network of the porous hydrogel microspheres.

[0049] Furthermore, X-ray photoelectron spectroscopy analysis showed that the relevant elements and their chemical states in the porous hydrogel microspheres were consistent with the multi-component polymer system and cross-linking mode, indicating that the cross-linking process could proceed smoothly under emulsification conditions, and the resulting porous hydrogel microspheres had a stable chemical composition and structure.

[0050] The above structural characterization results demonstrate that the multi-component polymer system used in this invention can successfully construct a stable porous hydrogel microsphere network structure under emulsification and crosslinking conditions.

[0051] b. Application: Porous hydrogel microspheres were prepared in Examples 1 to 3 of this invention, and the results were comparable. The dye adsorption performance of the porous hydrogel microspheres in Example 1 is verified as follows: Porous hydrogel microspheres were placed in an aqueous solution containing methylene blue, and the effects of different experimental conditions on adsorption performance were systematically studied, including solution pH, adsorbent dosage, ambient temperature, contact time, and initial concentration of cationic dye.

[0052] The pore structure of the porous hydrogel microspheres prepared in this invention was characterized by gas adsorption-desorption testing. The test results are as follows: Figure 4 As shown in a and b in the figure. The results show that, compared with the hydrogel microspheres of Comparative Example 1 ( Figure 4 (a) Porous hydrogel microspheres from Example 1 ( Figure 4 b) exhibits obvious pore structure characteristics, with a large number of internal pores and a reasonable pore structure distribution. Further, this invention, by introducing a multi-component polymer system during the emulsification and crosslinking process, can effectively construct the porous structure inside the microspheres without sacrificing the template or undergoing complex post-processing, thus providing a structural basis for their adsorption and mass transfer related applications.

[0053] The thermal properties of the hydrogel microspheres prepared in this invention were characterized by thermogravimetric analysis and differential scanning calorimetry. The test results are as follows: Figure 4 As shown in c and d in the figure. The results show that the porous hydrogel microspheres of Example 1 of the present invention exhibit good thermal stability within the test temperature range, and their thermal behavior characteristics are consistent with the multi-component polymer system and cross-linking structure. This further indicates that the porous hydrogel microspheres prepared by the present invention have good structural stability and can meet the requirements for use in water treatment, adsorption separation, carrier materials, and other related application environments.

[0054] like Figure 5 As shown in a, b, c, d, and e, the porous hydrogel microspheres prepared in this invention can all exhibit significant adsorption of methylene blue (MB) molecules under different conditions.

[0055] like Figure 5 As shown in a, as the solution pH increases from acidic to alkaline, the equilibrium adsorption capacity of porous hydrogel microspheres for MB ( Q e Both the adsorption rate and removal rate were significantly improved, reaching their maximum values ​​under neutral to weakly alkaline conditions, indicating that higher pH is beneficial for enhancing the adsorption of cationic dyes on the surface of porous hydrogel microspheres.

[0056] like Figure 5 As shown in b, with the increase of the amount of porous hydrogel microspheres added, the adsorption capacity per unit mass decreases. Q e The removal rate gradually decreased, while the removal rate remained at a high level with slight fluctuations, indicating that the overall removal efficiency of the system tended to stabilize as the adsorption sites gradually became abundant.

[0057] like Figure 5 As shown in c, increasing the temperature can significantly improve... Q e The removal rate is high and tends to level off in the higher temperature range, indicating that the adsorption process has endothermic characteristics.

[0058] like Figure 5 As shown by d in the figure, the adsorption process proceeds rapidly in the initial stage. Q e The removal rate increases rapidly in a short period of time and then gradually reaches adsorption equilibrium, indicating that the porous structure of the porous hydrogel microspheres is conducive to the rapid mass transfer and adsorption of dye molecules.

[0059] like Figure 5 As shown in e, with the increase of the initial MB concentration, Q e The concentration continues to rise while the removal rate gradually decreases, reflecting typical adsorption behavior where adsorption sites tend to saturate under high concentration conditions.

[0060] The above results demonstrate that the porous hydrogel microspheres prepared by this invention exhibit good adsorption capacity under different conditions. Their interconnected porous structure facilitates the diffusion and mass transfer of solutes within the porous hydrogel microspheres, thus demonstrating stable and reliable application effects.

[0061] It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range, as well as any value between the two endpoints, can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described here to avoid redundancy. Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this invention.

Claims

1. A method for preparing porous hydrogel microspheres, characterized in that, Includes the following steps: Sodium alginate and polyvinyl alcohol were dissolved together in water to obtain a multi-component polymer aqueous solution. A multi-component polymer aqueous solution is added dropwise to an oil phase consisting of a continuous liquid paraffin and an emulsifier, causing the multi-component polymer aqueous solution to disperse into droplets, forming a water-in-oil emulsion. A water-in-oil emulsion and calcium chloride were mixed to induce an ionic crosslinking reaction of sodium alginate in the droplets. During the ionic crosslinking reaction, the multi-component polymer underwent phase separation and structural evolution inside the droplets and was fixed in situ under the crosslinking effect, resulting in porous hydrogel microspheres.

2. The method for preparing porous hydrogel microspheres according to claim 1, characterized in that, In the multi-component polymer aqueous solution, the mass percentage of sodium alginate is 1%~3% and the mass percentage of polyvinyl alcohol is 3%~7%.

3. The method for preparing porous hydrogel microspheres according to claim 1, characterized in that, The volume ratio of emulsifier to continuous phase liquid paraffin is 1:15~25.

4. The method for preparing porous hydrogel microspheres according to claim 1, characterized in that, The volume ratio of the multi-component polymer aqueous solution to the oil phase is 1:5~15.

5. The method for preparing porous hydrogel microspheres according to claim 1, characterized in that, The mass ratio of calcium chloride to sodium alginate is 1:0.02~0.

08.

6. The method for preparing porous hydrogel microspheres according to claim 1, characterized in that, The conditions for the ionic crosslinking reaction are: stirring at 200 rpm to 400 rpm for 2 h at 30℃ to 35℃.

7. A porous hydrogel microsphere prepared by the preparation method according to any one of claims 1 to 6, characterized in that, The porous hydrogel microspheres are spherical and have a three-dimensional continuous network of pores inside.

8. The application of the porous hydrogel microspheres according to claim 7 in the preparation of dye adsorbents.

Images