Preparation method and application of diatomite doped rosin-based polymer composite

Abstract

The present application belongs to the technical field of separation and purification of panax notoginseng saponins, and particularly relates to a preparation method and application of a diatomite-doped rosin-based polymer composite material. The preparation method comprises the following steps: using hydrogenated rosin glycol acrylate and methyl methacrylate to form monomers, adding a certain amount of diatomite, adding an initiator, a pore-forming agent and a solvent, and mixing to obtain an oil phase; using a polyvinyl alcohol aqueous solution as a water phase; and using a suspension polymerization method to synthesize the diatomite-doped rosin-based polymer composite material. The amount of diatomite added is 9-11% of the total mass of the hydrogenated rosin glycol acrylate, divinylbenzene and methyl methacrylate. The present application can significantly improve the equilibrium adsorption capacity and purity of the rosin-based polymer material for panax notoginseng saponins by doping. The composite material obtained by the present application is a high-efficiency and reusable biomass adsorbent, and can be used for separating and enriching panax notoginseng saponins.

Description

Technical Field

[0001] This invention relates to the field of separation and purification technology of total saponins from Panax notoginseng, specifically to a method for preparing a diatomaceous earth-doped rosin-based polymer composite material and its application. Background Technology

[0002] Total saponins of Panax notoginseng (PNS) are extracted from the roots and rhizomes of Panax notoginseng and are widely used as medicines and dietary supplements worldwide. The active ingredients of PNS are notoginsenoside-R1, ginsenoside-Rg1, Rd, Re, and Rb1, which have effects such as promoting blood circulation, inhibiting cerebral edema, reducing infarct area, protecting the liver, and inhibiting cell apoptosis. The crude extract of Panax notoginseng (Burk.) contains a variety of chemical components, making the separation and concentration of PNS challenging. Adsorption is a widely used separation and purification method. Silica gel and resins are commonly used adsorbents. Currently used adsorption resins, such as HDP100 and HP20, can effectively enrich PNS, but their adsorption capacity is limited to only 65 mg / g. -1 Therefore, developing adsorbents with high adsorption capacity is crucial for the separation and purification of PNS.

[0003] Rosin is extracted from the secretions of pine trees. The carboxyl groups in rosin can introduce double bonds, promoting polymerization and producing polymer materials. The hydrogenated phenanthrene ring structure in rosin significantly affects the chemical stability of polymerized rosin. As biomass-derived adsorbents, rosin-based derivative polymers have shown great potential in adsorbing and separating active ingredients from natural drugs. Our team has dedicated many years to the research of rosin-based PNS adsorbents and has attempted to develop various superior rosin-based materials as adsorbents for the separation and purification of PNS. Previously, we have increased the equilibrium adsorption capacity of PNS from 14.48 mg / g. -1 Increased to 127.97 mg / g -1 The purity of PNS increased from 35.37% to 80%. For example, the paper "Study on the Adsorption Characteristics of Rosin-Based Macroporous Adsorption Resins for Total Saponins of Panax notoginseng" (Hu Yingli, Lei Fuhou, et al., *Food Industry Technology*, February 2022, Vol. 43, No. 4) disclosed three rosin-based macroporous adsorption resins, each bearing carboxyl (-COOH), ester (-OR), and hydroxyl (-OH) groups. The results showed that the adsorption capacities of the three resins were 37.61 mg·g⁻¹, respectively. -1 14.48 mg·g -1 25.82 mg·g -1Macroporous resins with -COOH functional groups showed the best adsorption performance. The paper "Purification of Total Saponins from Panax notoginseng and Adsorption Mechanism using Rosin-Based Adsorption Resin" (Huang Jinfu, Lei Fuhou, et al., *Modern Food Science and Technology*, 2023, Vol. 39, No. 10) disclosed the synthesis of a novel rosin-based adsorption resin (RBAR) using hydrogenated rosin (β-acryloyloxyethyl) ester and methacrylic acid as monomers and divinylbenzene as a crosslinking agent. Under conditions of an initial PNS concentration of 6 mg / mL, a temperature of 328 K, a solid-liquid ratio of 0.046 g / mL, and an adsorption time of 180 min, the equilibrium adsorption capacity was 127.97 mg·g⁻¹. -1 Under optimal conditions, the total saponin content of Panax notoginseng was increased from 46% to 80% by RBAR purification of the PNS primary extract, showing better desorption and purification effects compared to commercial resin D101.

[0004] It is evident that different rosin-based adsorption resins can exhibit different adsorption capacities. There is an opportunity to develop rosin-based adsorbents with higher adsorption capacities for the separation and purification of PNS, and this work is of great significance to the separation and purification of PNS. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned problems by providing a method for preparing a diatomaceous earth-doped rosin-based polymer composite material and its application. This invention can significantly improve the equilibrium adsorption capacity and purity of rosin-based polymer materials for Panax notoginseng total saponins (PNS) through doping. The composite material obtained by this invention is a highly efficient and reusable biomass adsorbent that can be used for the separation and enrichment of PNS.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a diatomaceous earth-doped rosin-based polymer composite material includes the following steps: diatomaceous earth is incorporated into a monomer composed of hydrogenated rosin ethylene glycol acrylate and methacrylic acid, with divinylbenzene as a crosslinking agent, along with an initiator, pore-forming agent, and solvent, and mixed to obtain an oil phase; an aqueous polyvinyl alcohol solution is used as the aqueous phase; and the diatomaceous earth-doped rosin-based polymer composite material is synthesized by suspension polymerization; wherein the amount of diatomaceous earth incorporated is 9-11% of the total mass of hydrogenated rosin ethylene glycol acrylate, divinylbenzene, and methacrylic acid.

[0008] In this invention, preferably, the mass ratio of hydrogenated rosin ethylene glycol acrylate, divinylbenzene, methacrylic acid and diatomaceous earth is 5:3:2:0.9 to 1.1.

[0009] In this invention, preferably, the initiator is azobisisobutyronitrile or benzoyl peroxide, and its amount is 0.25% to 1% of the total mass of hydrogenated rosin ethylene glycol acrylate, divinylbenzene, and methacrylic acid.

[0010] In this invention, preferably, the amount of the pore-forming agent is 55-65% of the total mass of hydrogenated rosin ethylene glycol acrylate, divinylbenzene, and methacrylic acid.

[0011] In this invention, preferably, the solvent is ethyl acetate, and the mass-to-volume ratio of the total mass of hydrogenated rosin ethylene glycol acrylate, divinylbenzene, and methacrylic acid in the oil phase to the solvent is 1 g: 0.9-1.2 ml.

[0012] In this invention, preferably, the mass percentage of polyvinyl alcohol in the aqueous phase is 0.02-0.1%, and the volume ratio of solvent to deionized water is 1:5.

[0013] In this invention, preferably, the specific requirements for the suspension polymerization are as follows: the temperature of the aqueous phase is adjusted to 50-60℃ and maintained; the oil phase is added dropwise to the aqueous phase at a stirring rate of 260-300 rpm; after the addition is complete, the temperature is raised to 80±5℃ and reacted for 3-5 hours; then the temperature is further raised to 95-100℃ and boiled for 2 hours; after the reaction is complete, the bead-like pale yellow resin balls are filtered through a 20-60 mesh sieve; the resin is extracted twice with anhydrous ethanol using a Soxhlet extractor; then it is soaked in 95% vol ethanol for a certain period of time; the resin is transferred to a glass chromatographic column and extracted alternately with deionized water and 95% vol ethanol; finally, the resin is stored in deionized water to obtain a diatomaceous earth-doped rosin-based polymer composite material.

[0014] In the above polymerization process, preferably, the soaking time is 5 to 30 hours.

[0015] This invention also protects the diatomaceous earth-doped rosin-based polymer composite material prepared by the above preparation method.

[0016] The diatomaceous earth-doped rosin-based polymer composite material prepared by this invention has a good adsorption effect on total saponins of Panax notoginseng and can be used for the separation and purification of total saponins of Panax notoginseng.

[0017] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0018] 1. This invention synthesizes a novel biosorbent by combining inorganic diatomaceous earth (DT) with hydrogenated rosin ethylene glycol methacrylate, namely, a diatomaceous earth-doped rosin-based polymer composite material, or rosin polymer / diatomaceous earth microspheres (RPM / DT). Due to the physical bonding of diatomaceous earth inside and outside the microspheres, pore formation is promoted, resulting in a significant increase in the specific surface area of ​​RPM / DT (734.55 m²). 2 ·g-1 This exceeds the RPM (405.17m) of undoped diatomaceous earth. 2 ·g -1 The incorporation of diatomaceous earth also exposed active sites and weak chemical bonds, improving adsorption capacity. Static adsorption and desorption experiments showed that RPM without diatomaceous earth (DT) had a low equilibrium adsorption capacity for Panax notoginseng saponins (PNS), at 125.10 mg·g⁻¹. -1 The doped RPM / DT exhibits excellent adsorption capacity for total saponins of Panax notoginseng (PNS), with an equilibrium adsorption capacity of 427.96 mg·g⁻¹. -1 Furthermore, the use of RPM / DT significantly increased the content of total saponins (PNS) in the purified Panax notoginseng from 48.47% to 86.16%.

[0019] 2. The RPM / DT prepared by this invention is a regenerable biosorbent. Static adsorption experiments were repeatedly conducted in a "desorption-regeneration-adsorption" cycle. The results showed that after 15 regeneration cycles, the equilibrium adsorption capacity for PNS was between 382.60 and 422.47 mg·g⁻¹. -1 The purity of PNS remains between 78.78% and 86.81%, and it can be reused.

[0020] In summary, the diatomaceous earth-doped rosin-based polymer composite material of the present invention has a high specific surface area, a high adsorption capacity for PNS, and is reusable. It has potential application value in separating and enriching PNS from low-purity stock solutions. Attached Figure Description

[0021] Figure 1 SEM images of RPM prepared in Comparative Example 1 and RPM / DT prepared in Example 1;

[0022] Figure 2 EDX plots of RPM / DT prepared in Comparative Example 1 and Example 1;

[0023] Figure 3 XRD patterns of DT, RPM prepared in Comparative Example 1, and RPM / DT prepared in Example 1;

[0024] Figure 4 FTIR spectra of RPM / DT prepared in Example 1 and RPM prepared in Comparative Example 1;

[0025] Figure 5 Thermogravimetric analysis (TGA) curve of RPM prepared for Comparative Example 1;

[0026] Figure 6 Thermogravimetric analysis (TGA) curves of RPM / DT prepared in Example 1;

[0027] Figure 7 Particle size distribution of RPM / DT prepared in Example 1;

[0028] Figure 8 The isotherm diagrams for N2 adsorption-desorption are shown below, where (a) is RPM prepared in Comparative Example 1, (b) is RPM / DT prepared in Example 1, (c) is RPM / DT / PNS after adsorption of total saponins of Panax notoginseng by RPM / DT, and (d) is the adsorbent regenerated after adsorption of PNS, denoted as RPM / DT-RE.

[0029] Figure 9 The results of the regeneration test of the RPM / DT prepared in this invention are shown. Detailed Implementation

[0030] The technical solution of the present invention will be clearly and completely described below with reference to 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.

[0031] The reagents used in these embodiments of the invention were sourced from the following: methacrylic acid (MAA), isooctane, divinylbenzene (DVB), polyvinyl alcohol (PVA), diatomaceous earth (DT), and toluene, all from Shanghai Maclean Reagent Co., Ltd., China. Hydrogenated rosin ethylene glycol acrylate (HREGA) was prepared in-house. Acetonitrile was provided by Thermo Fisher Scientific (Shanghai, China). PNS (standard) was sourced from the China National Institutes for Food and Drug Control (Beijing), and PNS (48.47%) was sourced from Nanjing Yuanzhi Biotechnology Co., Ltd. Other reagents were analytical grade chemicals.

[0032] The preparation method of hydrogenated rosin ethylene glycol methacrylate (HREGA) is as follows: Weigh 600g of hydrogenated rosin, 300g of ethylene glycol and 18g of p-toluenesulfonic acid; add them to a 2000mL three-necked flask, purge with argon gas, and after the hydrogenated rosin is completely dissolved, turn on the mechanical stirrer, heat to 160℃ and react for 1h, then heat to 170℃ and react for 6h; after the reaction is completed, heat to 200℃ to distill off the liquid, cool to 60℃, then add 180g of acrylic acid, 1g of hydroquinone and 18g of p-toluenesulfonic acid, heat to 140℃ and stir for 5h, then reduce the pressure with a water pump for 0.5h to obtain hydrogenated rosin ethylene glycol methacrylate.

[0033] The following embodiments provide a method for preparing a diatomaceous earth-doped rosin-based polymer composite material, comprising the following steps: diatomaceous earth is incorporated into a monomer composed of hydrogenated rosin ethylene glycol acrylate and methacrylic acid, using divinylbenzene as a crosslinking agent, along with an initiator, pore-forming agent, and solvent, and mixed to obtain an oil phase; a polyvinyl alcohol aqueous solution is used as the aqueous phase; and the diatomaceous earth-doped rosin-based polymer composite material is synthesized by suspension polymerization; wherein the amount of diatomaceous earth incorporated is 9-11% of the total mass of hydrogenated rosin ethylene glycol acrylate, divinylbenzene, and methacrylic acid. Using the method of this invention, when the proportion of diatomaceous earth reaches an appropriate level, the specific surface area of ​​the rosin polymer / diatomaceous earth microspheres can be significantly increased, surface roughness can be improved, thereby enhancing the adsorption capacity for total saponins of Panax notoginseng.

[0034] In some preferred embodiments of the present invention, the mass ratio of hydrogenated rosin ethylene glycol acrylate, divinylbenzene, methacrylic acid, and diatomaceous earth is 5:3:2:0.9–1.1. When the ratio between monomers is within this range, the obtained microspheres have better mechanical strength, thus having higher application value.

[0035] In some preferred embodiments of the present invention, the initiator is azobisisobutyronitrile or benzoyl peroxide, and its amount is 0.25% to 1% of the total mass of hydrogenated rosin ethylene glycol acrylate, divinylbenzene, and methacrylic acid.

[0036] In some preferred embodiments of the present invention, the amount of the porogen is 55-65% of the total mass of hydrogenated rosin ethylene glycol acrylate, divinylbenzene, and methacrylic acid. The selection of the porogen ensures suitable porosity and pore size, thereby obtaining microsphere materials with suitable mechanical strength and good specific surface area.

[0037] In this invention, preferably, the solvent is ethyl acetate, and the mass-to-volume ratio of the total mass of hydrogenated rosin ethylene glycol acrylate, divinylbenzene, and methacrylic acid in the oil phase to the solvent is 1 g: 0.9-1.2 ml.

[0038] In some preferred embodiments of the present invention, the mass percentage of polyvinyl alcohol in the aqueous phase is 0.02% to 0.1%, and the volume ratio of solvent to deionized water is 1:5.

[0039] In this invention, preferably, the specific requirements for the suspension polymerization are as follows: the temperature of the aqueous phase is adjusted to 50-60℃ and maintained; the oil phase is added dropwise to the aqueous phase at a stirring rate of 260-300 rpm; after the addition is complete, the temperature is raised to 80±5℃ and reacted for 3-5 hours; then the temperature is further raised to 95-100℃ and boiled for 2 hours; after the reaction is complete, the bead-like pale yellow resin balls are filtered through a 20-60 mesh sieve; the resin is extracted twice with anhydrous ethanol using a Soxhlet extractor; then it is soaked in 95% vol ethanol for 5-30 hours; the resin is transferred to a glass chromatographic column and extracted alternately with deionized water and 95% vol ethanol; finally, the resin is stored in deionized water to obtain a diatomaceous earth-doped rosin-based polymer composite material.

[0040] I. Preparation Examples

[0041] Example 1

[0042] A method for preparing a diatomaceous earth-doped rosin-based polymer composite material includes the following steps:

[0043] (1) Preparation of oil phase: Weigh 5.0g hydrogenated rosin ethylene glycol acrylate, 3.0g divinylbenzene (crosslinking agent), 2.0g methacrylic acid, 1.0g diatomaceous earth, add 0.025g azobisisobutyronitrile (initiator), 3.0g isooctane (porogen), 3.0g toluene (porogen) and 10ml ethyl acetate, and mix them evenly in a container to obtain the oil phase;

[0044] (2) Preparation of aqueous phase: Add 0.01g of polyvinyl alcohol and 50.0mL of deionized water to another container, and heat until PVA dissolves to form an aqueous phase;

[0045] (3) Suspension polymerization: The temperature of the aqueous phase was lowered to 55℃±1℃ and maintained. The oil phase was added dropwise to the aqueous phase at a stirring rate of 280 rpm. After the addition was complete, the temperature was raised to 80±5℃ and reacted for 4 h. Then, the temperature was raised to 95-100℃ and boiled for 2 h. After the reaction was complete, the pale yellow resin beads were filtered through a 50-mesh sieve. The resin was extracted twice with anhydrous ethanol using a Soxhlet extractor and then soaked in 95% vol ethanol for 10 h. The resin was transferred to a glass chromatographic column and extracted alternately with deionized water and 95% vol ethanol. Finally, the resin was stored in deionized water to obtain the diatomaceous earth-doped rosin-based polymer composite material RPM / DT.

[0046] Example 2

[0047] A method for preparing a diatomaceous earth-doped rosin-based polymer composite material includes the following steps:

[0048] (1) Preparation of oil phase: Weigh 5.0g hydrogenated rosin ethylene glycol acrylate, 3.0g divinylbenzene (crosslinking agent), 2.0g methacrylic acid, 0.9g diatomaceous earth, add 0.06g azobisisobutyronitrile (initiator), 2.5g isooctane (porogen), 3.0g toluene (porogen) and 9ml ethyl acetate, and mix them evenly in a container to obtain the oil phase;

[0049] (2) Preparation of aqueous phase: Add 0.045g of polyvinyl alcohol and 45.0mL of deionized water to another container, and heat until the PVA dissolves to form an aqueous phase;

[0050] (3) Suspension polymerization: The temperature of the aqueous phase was lowered to 50℃±1℃ and maintained. The oil phase was added dropwise to the aqueous phase at a stirring speed of 260 rpm. After the addition was complete, the temperature was raised to 80±5℃ and reacted for 3 h. Then, the temperature was raised to 95-100℃ and boiled for 2 h. After the reaction was complete, the pale yellow resin beads were filtered through a 20-mesh sieve. The resin was extracted twice with anhydrous ethanol using a Soxhlet extractor and then soaked in 95% vol ethanol for 5 h. The resin was transferred to a glass chromatographic column and extracted alternately with deionized water and 95% vol ethanol. Finally, the resin was stored in deionized water to obtain the diatomaceous earth-doped rosin-based polymer composite material RPM / DT.

[0051] Example 3

[0052] A method for preparing a diatomaceous earth-doped rosin-based polymer composite material includes the following steps:

[0053] (1) Preparation of oil phase: Weigh 5.0g hydrogenated rosin ethylene glycol acrylate, 3.0g divinylbenzene (crosslinking agent), 2.0g methacrylic acid, 1.1g diatomaceous earth, add 0.1g azobisisobutyronitrile (initiator), 3.5g isooctane (porogen), 3.0g toluene (porogen) and 12ml ethyl acetate, and mix them evenly in a container to obtain the oil phase;

[0054] (2) Preparation of aqueous phase: Add 0.03g of polyvinyl alcohol and 60.0mL of deionized water to another container, and heat until PVA dissolves to form an aqueous phase;

[0055] (3) Suspension polymerization: The temperature of the aqueous phase was lowered to 60℃ and maintained. The oil phase was added dropwise to the aqueous phase at a stirring speed of 300 rpm. After the addition was complete, the temperature was raised to 80±5℃ and reacted for 5 h. Then, the temperature was raised to 95-100℃ and boiled for 2 h. After the reaction was complete, the pale yellow resin beads were filtered through a 60-mesh sieve. The resin was extracted twice with anhydrous ethanol using a Soxhlet extractor and then soaked in 95% vol ethanol for 30 h. The resin was transferred to a glass chromatographic column and extracted alternately with deionized water and 95% vol ethanol. Finally, the resin was stored in deionized water to obtain the diatomaceous earth-doped rosin-based polymer composite material RPM / DT.

[0056] Comparative Example 1

[0057] The difference between Comparative Example 1 and Example 1 is that diatomaceous earth DT was not added in Comparative Example 1, and the product RPM was prepared. All other steps were the same as in Example 1.

[0058] Comparative Example 2

[0059] The difference between Comparative Example 2 and Example 1 is that the mass of diatomaceous earth DT added in Comparative Example 2 is 0.5g, while the other steps are the same as in Example 1.

[0060] Comparative Example 3

[0061] The difference between Comparative Example 3 and Example 1 is that the mass of diatomaceous earth DT added in Comparative Example 3 is 1.5g, while the other steps are the same as in Example 1.

[0062] Comparative Example 4

[0063] The difference between Comparative Example 4 and Example 1 is that the amount of monomers used in preparing the oil phase in Comparative Example 4 is different. Specifically, 2.5g of hydrogenated rosin ethylene glycol acrylate, 3.0g of divinylbenzene (crosslinking agent), 4.5g of methacrylic acid, and 1.0g of diatomaceous earth were weighed, and 0.025g of azobisisobutyronitrile (initiator), 3.0g of isooctane (porogen), 3.0g of toluene (porogen) and 10ml of ethyl acetate were added and mixed evenly in a container to obtain the oil phase. All other steps were the same as in Example 1.

[0064] Comparative Example 5

[0065] The difference between Comparative Example 5 and Example 1 is that the amount of monomers used in preparing the oil phase in Comparative Example 4 is different. Specifically, 3.5g of hydrogenated rosin ethylene glycol acrylate, 3.0g of divinylbenzene (crosslinking agent), 3.5g of methacrylic acid, and 1.0g of diatomaceous earth were weighed, and 0.025g of azobisisobutyronitrile (initiator), 3.0g of isooctane (porogen), 3.0g of toluene (porogen) and 10ml of ethyl acetate were added and mixed evenly in a container to obtain the oil phase. All other steps were the same as in Example 1.

[0066] Comparative Example 6

[0067] The difference between Comparative Example 6 and Example 1 is that the amount of monomers used in preparing the oil phase in Comparative Example 4 is different. Specifically, the difference between Comparative Example 4 and Example 1 is that the amount of monomers used in preparing the oil phase in Comparative Example 4 is different. Specifically, 6.0g of hydrogenated rosin ethylene glycol acrylate, 3.0g of divinylbenzene (crosslinking agent), 1.0g of methacrylic acid, and 1.0g of diatomaceous earth were weighed, and 0.025g of azobisisobutyronitrile (initiator), 3.0g of isooctane (porogen), 3.0g of toluene (porogen) and 10ml of ethyl acetate were added and mixed evenly in a container to obtain the oil phase. All other steps were the same as in Example 1.

[0068] II. Material Characterization

[0069] The carbon and hydrogen contents of RPM / DT were determined using an elemental analyzer (Elemantar Vario EL cube, Germany). The functional groups of RPM / DT were analyzed using an infrared spectrometer (Nicolet IS10, Thermo Fisher Scientific, USA). The surface morphology of RPM / DT was observed using a SEM (ZeissSigma 300, Germany). The stability of RPM / DT was analyzed using a thermogravimetric analyzer (TGA5500, Germany). N2 adsorption and desorption were determined using an ASAP2020 pore size analyzer (Micromeritics, USA). RPM / DT particles were characterized using laser particle size distribution (Mastersizer 3000, Malvern, UK). Crystal characteristics were determined using X-ray diffraction (XRD, Bruker, Germany). The test results are analyzed below:

[0070] 1. SEM-EDX Analysis

[0071] SEM images and EDX elemental surface distribution maps of the RPM / DT prepared in Example 1 and the RPM prepared in Comparative Example 1 are shown below. Figure 1 and Figure 2 As shown. At low magnification (60x and 150x), the diameters of RPM and RPM / DT particles are in the range of 400-600 μm, and they exhibit satisfactory sphericity. RPM has a smooth surface, while RPM / DT displays embedded plate-like DT or DT fragments, resulting in a greater degree of roughness than RPM. At 10,000x magnification, the pore structure of the RPM surface is not easily identifiable. In contrast, RPM / DT has both a rough surface and a pronounced porous structure. In the presence of DT, the particle core pore factor diffuses to the surface during polymerization, leading to the appearance of these pores. The surface roughness and porous structure also increase the contact area between the microspheres and PNS, thereby exposing a large number of PNS adsorption active sites.

[0072] In Comparative Example 2, the amount of diatomaceous earth doped was relatively small, resulting in microspherical adsorption resin. In Comparative Example 3, the amount of diatomaceous earth doped was relatively large, resulting in microspheres with poor mechanical strength and easy breakage; therefore, no further characterization was performed. In Comparative Examples 4-6, when the amount of monomer varied, the spheres were relatively soft, and hard microspheres could not be obtained, lacking particle strength. Since the lack of particle strength in the adsorption resin is detrimental to storage and transportation, and during industrial column use, shrinkage and swelling caused by solvent conversion or dehydration can easily lead to resin particle breakage, no further characterization was performed.

[0073] Surface EDX elemental analysis showed that the RPM prepared in Comparative Example 1 was composed of C and O elements, and the distribution was uniform. The relative contents of C and O elements were 86.14% and 12.39%, respectively. The RPM / DT surfaces prepared in Examples 1-3 contained C, O, and Si elements, with relative contents of 80.62%, 17.76%, and 1.14%, respectively.

[0074] 2. XRD Analysis

[0075] Figure 3 XRD patterns of DT, RPM prepared in Comparative Example 1, and RPM / DT prepared in Example 1 are shown. It can be observed that the XRD pattern of DT matches the characteristic diffraction peaks of the standard card (PDF#99-0039) for Tetragonal SiO2. The diffraction peaks at 22.01, 28.49, 31.49, 36.16, 42.74, 44.91, 47.11, 53.85, 57.19, 62.13, and 65.21° correspond to the diffraction peaks of the (101), (111), (102), (200), (211), (202), (113), (221), (301), (302), and (312) crystal planes of SiO2, indicating good crystallinity. RPM has an amorphous carbon structure. The RPM / DT structure formed by doping with DT still retains strong diffraction peaks at 22.01°(101), 28.49°(111), 31.49°(102), and 36.16°(200), further indicating that DT has been successfully doped into RPM to form RPM / DT. This is consistent with SEM / EDX (…). Figure 1 , 2 ) and FTIR ( Figure 4 The results were consistent.

[0076] 3. Infrared spectroscopy analysis

[0077] Figure 4 FTIR spectra of RPM / DT prepared in Example 1 and RPM prepared in Comparative Example 1. RPM / DT at 1088 cm⁻¹ -1 The strong and broad absorption band is due to the Si-O-Si antisymmetric stretching vibration, 469 cm⁻¹. -1The peaks at the point are the bending vibrations of the Si-O bond, which are characteristic peaks of DT. RPM does not have these two peaks. It can be further inferred that DT has been successfully doped into RPM to form RPM / DT.

[0078] 4. Thermogravimetric analysis

[0079] Figure 5 and 6 Thermogravimetric analysis (TGA) curves of RPM prepared in Comparative Example 1 and RPM / DT prepared in Example 1 are shown. The thermal degradation of RPM can be divided into two distinct stages. The first stage of degradation begins at temperatures of 236.7–430.8 °C. In this stage, the main reactions are the breaking of polar bonds and partial decomposition of C / C bonds, resulting in a weight loss of 45.6%. The second stage occurs at temperatures of 430.8–661.8 °C. In this stage, the main reaction is the decomposition of the benzene ring, resulting in a weight loss of 49.9%. The remaining amount of RPM is 4.2%. The initial degradation temperature of RPM / DT is 276.6 °C. The first stage occurs at temperatures of 276.6–398.1 °C, with a weight loss of 26.2%. The second stage occurs at temperatures of 398.1–752.9 °C, with a weight loss of 30.5%. The remaining amount of RPM / DT is 42.9%. After calcination at 850 °C in a muffle furnace (SX2-4-10G, Shanghai Yuejin Medical Instrument Co., Ltd., China) to a fixed weight, the residue weight is 3.5%. Figure 3 In the calcination, the infrared spectrum of the residue (RPM / DT-R) was consistent with that of SiO2, indicating that SiO2 was the main component of the residue. These results suggest that the addition of DT improved the heat resistance of RPM / DT, thereby slowing down the degradation rate of the composite material. According to TGA results, RPM and RPM / DT exhibited good thermal stability below 200℃. Since the adsorption and desorption processes of PNS occur below 100℃, the thermal and chemical stability of RPM and RPM / DT makes them suitable for the separation and purification of PNS.

[0080] 5. Particle size distribution

[0081] The particle size distribution of RPM / DT was determined using laser particle size distribution method, and the average particle size of RPM / DT was calculated. Figure 7 As shown, the particle size distribution of RPM / DT is relatively uniform, with an average particle size of 440 μm. It is worth noting that there are particles with a volume of 1.14% in the range of 15.16-44.10 μm. This may be because the ultrasonic treatment during the test caused DT flakes or fragments to fall off the surface of RPM / DT, which is consistent with the SEM analysis results.

[0082] 6. N2 adsorption desorption

[0083] The isotherms of N2 adsorption-desorption at RPM, RPM / DT, RPM / DT / PNS, and RPM / DT-RE are as follows: Figure 8 As shown in Table 1, RPM was prepared as a comparative example, RPM / DT as prepared in Example 1, RPM / 0.5DT as prepared in Comparative Example 2, and RPM / DT / PNS as the RPM / DT prepared in Example 1 that adsorbed PNS. RPM / DT-RE was the adsorbent regenerated after adsorbing PNS. All of these curves belong to Type IV, exhibiting a Type H1 hysteresis loop, indicating a relatively uniform pore size distribution and mesoporous characteristics. Under relatively low relative pressures (P / P0), the adsorption capacity of N2 increases rapidly, and a hysteresis loop appears in the range of P / P0 = 0.4–1.0, indicating the presence of both micropores and mesopores.

[0084] Table 1. Parameters of N2 adsorption-desorption isotherms for RPM, RPM / DT, RPM / DT / PNS, and RPM / DT-RE

[0085]

[0086] Table 1 shows the specific surface area of ​​RPM / DT (734.55 m²). 2 ·g -1 It is significantly higher than RPM (405.17m). 2 ·g -1 ), and higher than RPM / 0.5DT (438.81m 2 ·g -1 Furthermore, the average pore size of RPM / DT (9.56 nm) is greater than that of RPM (5.55 nm). These findings further confirm that the addition of an appropriate amount of DT can not only modify the inherent components of the resin to increase the specific surface area, but also create pore channels through DT embedding, making the pore structure of the resin more obvious. When the amount of DT is small, the increase in specific surface area is very limited, while when the amount of DT is too large, the sphere strength is low and it is easy to break. Therefore, it can be inferred that the presence of an appropriate amount of DT leads to an increase in the specific surface area of ​​RPM / DT. In most cases, specific surface area is related to small size and extremely rough surface. The specific surface area of ​​RPM / DT / PNS after adsorption of total Panax notoginseng saponins is 127.98 nm. 2 ·g -1 This indicates that most of the surface area of ​​RPM / DT is occupied by PNS. The average pore size of RPM / DT / PNS is 19.24 nm, which is much larger than the average pore size of RPM / DT (9.56 nm). This is because PNS fills the smaller pores in RPM / DT, increasing the average pore size. RPM / DT and regenerated RPM / DT-RE have similar isotherms and pore size distributions, while RPM / DT-RE exhibits mesoporous characteristics (average pore size of 7.60 nm).

[0087] III. Adsorption and Desorption Performance

[0088] Application Example 1

[0089] 1. Establishment of the PNS standard curve

[0090] The concentration of the PNS standard solution is 2.5 mg / mL. -1 The concentrations of individual components R1, Rg1, Re, Rb1, and Rd were 0.5, 0.63, 0.25, 0.75, and 0.37 mg·mL, respectively. -1 Peak area (x, mAU) versus concentration (y, mg·mL) -1 The relationships are linear and can be expressed as follows: R1,y1=0.00000062434x+0.00305,R2=0.9999; Rg1,y2=0.0000005106x+0.01901,R2=0.9995; Re,y3=0.0000008854x-0.000751,R2=0.9971; Rb1,y4=0.0000007215x-0.02110,R2=0.9998; Rd,y5=0.0000006347x-0.000934,R2=0.9999.

[0091] 2. Static adsorption-desorption experiment of PNS on RPM / DT

[0092] Weigh 0.114 g of RPM / DT prepared in Example 1 and 0.114 g of RPM prepared in Comparative Example 1 into separate single-necked flasks, and add 20 mL of each flask containing 6 mg·mL⁻¹ of RPM. -1 PNS was adsorbed at 150 rpm under a constant temperature water bath at 50 °C for 540 min. The adsorbed solution was then analyzed by high performance liquid chromatography (HPLC) to determine the concentration of PNS. 10 μL of PNS solution was used for each analysis. The adsorption rate (A, %), purity (P, %), and adsorption capacity (q, mg·g) of PNS for RPM / DT were calculated using the following formulas. -1 ).

[0093]

[0094]

[0095]

[0096]

[0097] C0, C t and C e (mg·mL -1 C1 (mg·mL⁻¹) represents the initial, t, and equilibrium PNS concentrations, respectively. -1The concentration of PNS in the eluent is V (mL). V represents the volume of the PNS solution, m0 (g) represents the RPM / DT or RPM mass, and q represents the concentration of PNS in the eluent. t and q e (mg·g -1 The numbers ) represent the adsorption amounts of PNS on RPM / DT at t and equilibrium, respectively. When determining purity, C... p (mg·mL -1 ) represents PNS concentration, V p (mL) represents the volume of the PNS solution, m p (mg) indicates the mass of PNS. Test results are shown in Table 2 below.

[0098] Table 2 Adsorption test results

[0099] 1 RPM 125.10 98.52 80.03 2 DT 0.47 0.55 / 3 RPM / DT 427.96 91.33 86.16

[0100] It can be seen that the adsorption capacity of total saponins of Panax notoginseng on RPM is only 125.10 mg·g. -1 This is much smaller than the adsorption capacity on RPM / DT (427.96 mg·g). -1 The adsorption capacity of PNS for DT is only 0.47 mg·g. -1 It can be seen that the presence of DT increases the specific surface area of ​​the resin microspheres, exposing weaker chemical bonds and more active sites to drive the adsorption process of PNS, thereby improving the adsorption capacity of RPM / DT.

[0101] 3. Adsorbent regeneration

[0102] Adsorbent regeneration can extend its service life, reduce production costs, and minimize waste generation. Regenerability is a crucial indicator of adsorption performance. Regenerated adsorbents require high adsorption capacity and stability. In the regeneration experiment, RPM / DT / PNS after adsorption equilibrium was added to 25.0 mL of desorption solvent (50% ethanol), shaken at 50°C for 2 h, and then the RPM / DT was rinsed with deionized water until no foam remained. Static adsorption experiments were repeated with RPM / DT in a "desorption-regeneration-adsorption" cycle. Results are as follows: Figure 9 As shown in the figure. It can be seen from the figure that after 15 regeneration cycles, the PNS RPM / DT q e It did not decrease, but remained between 382.60 and 422.47 mg / g. -1 The purity ranged from 78.78% to 86.81%, with the lowest purity observed after the first use, possibly due to the detachment of the DT fragment. The regeneration results were consistent with the N2 adsorption-desorption analysis, indicating that RPM / DT has good regeneration performance.

[0103] The above description is a detailed description of the preferred embodiments of the present invention. However, the embodiments are not intended to limit the scope of the patent application of the present invention. All equivalent changes or modifications made under the technical spirit of the present invention should fall within the patent scope covered by the present invention.

Claims

1. A method for preparing a diatomaceous earth-doped rosin-based polymer composite material, characterized in that, Includes the following steps: The diatomaceous earth-doped rosin-based polymer composite material is synthesized by using hydrogenated rosin acrylate and methacrylic acid as monomers, divinylbenzene as a crosslinking agent, and a certain amount of diatomaceous earth as a crosslinking agent. An initiator, a pore-forming agent, and a solvent are added, and the mixture is then mixed to obtain an oil phase. A polyvinyl alcohol aqueous solution is used as the aqueous phase. The diatomaceous earth is incorporated at 9-11% of the total mass of hydrogenated rosin acrylate, divinylbenzene, and methacrylic acid. The mass ratio of hydrogenated rosin acrylate, divinylbenzene, methacrylic acid, and diatomaceous earth is 5:3:2:0.9-1.

1. The solvent is ethyl acetate, and the mass-to-volume ratio of the total mass of hydrogenated rosin acrylate, divinylbenzene, and methacrylic acid in the oil phase to the solvent is 1 g:0.9-1.2 ml.

2. The preparation method according to claim 1, characterized in that: The initiator is azobisisobutyronitrile, and its dosage is 0.25% to 1% of the total mass of hydrogenated rosin ethylene glycol acrylate, divinylbenzene, and methacrylic acid.

3. The preparation method according to claim 1, characterized in that: The amount of the pore-forming agent is 55-65% of the total mass of hydrogenated rosin ethylene glycol acrylate, divinylbenzene, and methacrylic acid.

4. The preparation method according to claim 1, characterized in that: The mass percentage of polyvinyl alcohol in the aqueous phase is 0.02-0.1%, and the volume ratio of solvent to deionized water is 1:

5.

5. The preparation method according to claim 1, characterized in that, The specific requirements for the suspension polymerization are as follows: the temperature of the aqueous phase is adjusted to 50-60℃ and maintained. The oil phase is added dropwise to the aqueous phase at a stirring speed of 260-300 rpm. After the addition is complete, the temperature is raised to 80±5℃ and reacted for 3-5 hours. Then, the temperature is further raised to 95-100℃ and boiled for 2 hours. After the reaction is complete, the resin beads are filtered through a 20-60 mesh sieve to obtain pale yellow resin spheres. The resin is extracted twice with anhydrous ethanol using a Soxhlet extractor, and then soaked in 95% vol ethanol for a certain period. The resin is transferred to a glass chromatography column and extracted alternately with deionized water and 95% vol ethanol. Finally, the resin is stored in deionized water to obtain a diatomaceous earth-doped rosin-based polymer composite material.

6. The preparation method according to claim 5, characterized in that: The soaking time is 5 to 30 hours.

7. The diatomaceous earth-doped rosin-based polymer composite material prepared by the preparation method according to any one of claims 1 to 6.

8. The diatomaceous earth-doped rosin-based polymer composite material prepared by any one of claims 1 to 6 is used for the separation and purification of total saponins from Panax notoginseng.

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