Preparation method of magnetic porous nano polymer for adsorbing polychlorinated biphenyl pollution

Abstract

The invention relates to the technical field of polychlorinated biphenyl pollution adsorption, and discloses a preparation method of a magnetic porous nano polymer for adsorbing polychlorinated biphenyl pollution, unsaturated polyester resin is used as a raw material, iron oxide is loaded after carbonization to prepare magnetic porous carbon, cyclodextrin is immobilized in a polymer network through an emulsion template method, and the magnetic porous nano polymer for adsorbing polychlorinated biphenyl pollution is obtained. The magnetic porous nano polymer disclosed by the invention shows excellent selective adsorption capacity on polychlorinated biphenyl, can reach adsorption equilibrium within 5min, and has a high recovery rate on various polychlorinated biphenyl. And the material is rapidly separated through a magnet and can be recycled through multiple times of adsorption and desorption, and the recovery rate can still reach more than 80% after the material is repeatedly used for five times, so that the performance is stable. The preparation method of the adsorbing material is clear, and the adsorbing material is an efficient, high-selectivity and reproducible adsorbent with wide application prospects in polychlorinated biphenyl pollution treatment.

Description

Technical Field

[0001] This invention relates to the field of polychlorinated biphenyl (PCB) pollution adsorption technology, specifically to a method for preparing a magnetic porous nanopolymer for adsorbing PCB pollution. Background Technology

[0002] Polychlorinated biphenyls (PCBs) comprise 209 homologues depending on the number and position of chlorine atoms on the benzene ring. They are typical aromatic halides, structurally stable, and possess excellent thermal conductivity, insulation, and inertness. They are widely used as flame retardants in plastics, textiles, and building materials, as additives in paints, and as impregnating agents in electrical capacitors. However, due to their structural stability, they persist in the environment for extended periods, accumulating in organisms through the food chain and causing significant toxic side effects on the nervous, endocrine, reproductive, and immune systems. They are considered persistent environmental pollutants (POPs) and are subject to widespread attention and strict control globally. The C-Cl bond in the PCB molecule exhibits strong stability; even decades after their ban, PCBs remain frequently detected in various environmental media, posing a complex pollution threat to the ecological environment and human health. Therefore, the efficient removal of PCB pollutants from environmental water bodies and soil is of significant practical importance for protecting the ecological environment and human health.

[0003] Currently, the main technologies for treating polychlorinated biphenyls (PCBs) pollution in environmental media include three main approaches: physical adsorption, chemical methods, and microbial remediation. Chemical methods rely on strong oxidants or high temperatures, while biodegradation is limited by the activity of microorganisms and the stability of electron acceptor supply. In comparison, adsorption methods offer advantages such as lower process complexity, controllable unit treatment costs, and high dynamic adsorption capacity. Some adsorbents can also be regenerated through thermal desorption or chemical washing, demonstrating significant competitiveness in practical applications. Classic porous adsorbents such as activated carbon (AC) are widely used due to their unique pore structure. Graphene-based activated carbon (GAC), after directional activation, can maintain a stable specific surface area of ​​2680–2740 m². 2 / g, total pore volume is 0.73–2.00 cm³ 3The adsorption capacity is / g, and it exhibits a gradient microporous-mesoporous composite distribution. This multi-scale pore network forms a dual space-energy matching mechanism with the hydrophobicity and molecular dynamic diameter of polychlorinated biphenyls (PCBs). This allows the micropores to enhance hydrophobic interactions through confinement effects, while the mesopores promote the molecular diffusion dynamics of PCBs. Combined with the π-π electron cloud stacking effect, it achieves excellent removal efficiency for PCBs. It is worth noting that the performance of AC is highly dependent on the preparation process. Biomass direct carbonization products, lacking an activation step, typically have low SSA (Specific Surface Area) and poor pore connectivity, resulting in insufficient adsorption capacity and a tendency to release trapped target pollutants during desorption. The dispersion of the product's pore size distribution remains a bottleneck.

[0004] In recent years, researchers have focused on functionalizing adsorbent materials through molecular engineering and interface regulation strategies to address key challenges in regeneration and selectivity. These strategies primarily include three approaches: magnetic functionalization, directional functional group modification, and polymer composite modification. Cyclodextrins (CDs) are cyclic oligosaccharides formed by glucose molecules linked by α-1,4-glycosidic bonds. β-Cyclodextrin, composed of seven glucose units, possesses a cavity size optimally matched to the structure of polychlorinated biphenyls (PCBs), providing ideal spatial conditions for efficient adsorption. Furthermore, existing technologies have achieved specific adsorption of PCB28 and PCB52 through host-guest inclusion interactions within the β-CD cavity, with adsorption capacities of 30.32 mmol / kg for PCB52 and 40.01 mmol / kg for PCB28. However, during the synthesis process, the saturation magnetization decreased from 62.13 emu / g to 37.57 emu / g. This was due to the uneven distribution of magnetic responsiveness caused by the non-uniform core-shell interface, making the adsorbent prone to magnetic leakage in the dynamic adsorption system. Furthermore, the insufficient bonding strength at the silanization interface of the synthesized material resulted in the β-CD layer of the composite material being easily hydrolyzed and detached, severely limiting its practical engineering applications. In contrast, the chitosan-polyphenylene diamine (CS-PPD) magnetic nanocomposite material exhibits superior stability and adsorption kinetics. This material is produced by in-situ chemical polymerization to coat the surface of Fe3O4 material with a polyaniline network. The resulting cross-linked structure significantly enhances the hydrolysis resistance of the magnetic material. Simultaneously, the composite surface possesses abundant amino (-NH2), carboxyl (-COOH) groups and forms a π-conjugated system. This mechanism greatly improves the material's adsorption efficiency, enabling a PCB recovery rate of 94%-108% within 3 minutes. However, this material still has significant drawbacks. SEM images show that the polymer network forms a non-uniform porous structure with significant dispersion in pore size distribution, and micropores account for less than 15%, which weakens the material's adsorption capacity for small molecule pollutants. Furthermore, the rigid framework of polyaniline offers poor morphological control, making it difficult to precisely regulate the density and spatial distribution of surface functional groups through subsequent modifications, thus limiting the material's selective adsorption effect. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing magnetic porous nanopolymers for adsorbing polychlorinated biphenyl (PCB) pollution. This method solves two problems in existing technologies: firstly, functional layers grafted via silanization (such as β-cyclodextrin) often exhibit insufficient interfacial bonding, leading to hydrolysis and detachment during chemical washing, resulting in a rapid decline in material selectivity and regeneration capacity; secondly, while polymer composites prepared by in-situ polymerization show improved stability, their polymer networks often form non-uniform porous structures with poor morphological controllability, making it difficult to precisely regulate pore size distribution and surface functional groups, thus limiting their adsorption capacity for small molecule pollutants and their selectivity for specific targets.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a magnetic porous nanopolymer for adsorbing polychlorinated biphenyl (PCB) contaminants, comprising the following steps:

[0007] Step a, Preparation of magnetic porous carbon: Unsaturated polyester resin was used as a precursor and carbonized. The carbonization product was then reacted with urea to construct the framework of a porous carbon material. Iron oxides were then loaded onto the formed porous carbon material via chemical co-precipitation to obtain magnetically responsive porous carbon.

[0008] In one specific embodiment, the process of loading iron oxide involves adding a ferrous salt and an iron salt to an aqueous solution of porous carbon material and reacting under an inert gas atmosphere to generate and load the iron oxide onto the porous carbon in situ. Further, the ferrous salt can be ferrous chloride tetrahydrate, and the iron salt can be ferric chloride hexahydrate.

[0009] Step b, Ethylene functionalization: The magnetic porous carbon obtained in step a is reacted with a vinyl-containing reagent to graft vinyl functional groups onto the surface of the magnetic porous carbon material, thereby obtaining ethylene-functionalized magnetic porous carbon with polymerization reactivity.

[0010] In one specific embodiment, the vinyl-containing reagent is acryloyl chloride, and the grafting reaction is carried out in a dimethylformamide solvent in the presence of triethylamine.

[0011] Step c, Polymerization Reaction: The final nanopolymer is constructed through polymerization using an emulsion template method. This step specifically includes preparing an aqueous solution and an oil solution. The aqueous solution contains cyclodextrin as a molecular recognition unit. The oil solution contains the ethylene-functionalized magnetic porous carbon obtained in step b, polymerizing monomers, and a crosslinking agent. The aqueous and oil solutions are mixed in the presence of an emulsifier to form an emulsion, which is then used to initiate the polymerization reaction. After the polymerization reaction is complete, the resulting polymer product is purified to obtain the magnetic porous nanopolymer.

[0012] Specifically, the loaded iron oxides give the final material macroscopic magnetic responsiveness, enabling rapid solid-liquid separation under an applied magnetic field; the porous carbon itself and the porous structure formed by emulsion polymerization provide high specific surface area and material transport channels; the hydrophobic cavity structure of cyclodextrin molecules matches the size and polarity of specific polychlorinated biphenyl molecules, achieving selective capture of target pollutant molecules through host-guest inclusion.

[0013] In one specific implementation, the emulsion template method described in step c is a concentrated emulsion template method to construct a through structure with high porosity.

[0014] In one specific embodiment, the aqueous solution comprises water, cyclodextrin, and potassium persulfate as a polymerization initiator.

[0015] In one specific embodiment, the components of the oil phase solution include: ethylene-functionalized magnetic porous carbon, acrylamide as a polymerization monomer, ethylene glycol dimethacrylate as a crosslinking agent, and Span 80 as an emulsifier.

[0016] In one specific embodiment, the polymerization reaction temperature is set to 50-70°C, and the reaction time is 20-30 hours.

[0017] In one specific embodiment, the purification process includes the following steps: washing the polymerization product sequentially with hot water and ethanol, and then performing Soxhlet extraction on the polymerization product using an ethanol-acetic acid solution.

[0018] This invention provides a method for preparing a magnetic porous nanopolymer that adsorbs polychlorinated biphenyl (PCB) contaminants.

[0019] It has the following beneficial effects:

[0020] 1. This invention introduces cyclodextrin into the polymer structure, utilizing its molecular cavity with specific size and hydrophobic properties to achieve structural matching with specific polychlorinated biphenyl molecules such as PCB118, PCB153, PCB138 and PCB180. Through host-guest inclusion, selective adsorption is generated, enabling the material prepared by this invention to have the ability to directionally adsorb specific pollutants.

[0021] 2. This invention forms a multi-level pore structure by combining a porous carbon skeleton with a polymer network constructed by the emulsion template method. This increases the specific surface area and exposes a large number of adsorption active sites, thereby achieving a high adsorption capacity. At the same time, the multi-level pore structure can also reduce the mass transfer resistance of polychlorinated biphenyl molecules inside the material, enabling them to quickly reach the active sites and achieve rapid adsorption.

[0022] 3. This invention incorporates iron oxide components into the material, enabling the polymer to possess magnetic responsiveness. As a result, after the material has adsorbed pollutants in the liquid phase, there is no need for filtration or centrifugation. The material can be rapidly and in-situ separated and recovered by simply applying an external magnetic field, simplifying the post-processing procedures.

[0023] 4. This invention fixes the cyclodextrin functional unit and the magnetic porous carbon substrate in the cross-linked polymer network through a polymerization reaction, thereby producing a chemical bonding fixation effect, effectively preventing the loss of active components during elution and reuse, ensuring the stability of the material structure and the durability of its function, and thus realizing the recycling of multiple adsorption and desorption cycles. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of selective adsorption testing for CMPP, MPCNP1, and MPCNP2 according to the present invention.

[0025] Figure 2 This is a schematic diagram of the Langmuir fitting curve of MPCNP1 of the present invention;

[0026] Figure 3 This is a schematic diagram of the Freundlich fitting curve of MPCNP2 of the present invention;

[0027] Figure 4 This is a schematic diagram of the quasi-first-order dynamic fitting of the MPCNP1 of the present invention;

[0028] Figure 5 This is a schematic diagram of the quasi-second-order dynamic fitting of MPCNP1 in this invention;

[0029] Figure 6 This is a schematic diagram of the repeatability test results for the MPCNP1 of the present invention;

[0030] Figure 7 This is a scanning electron microscope image of the unsaturated polyester resin of the present invention;

[0031] Figure 8 This is a scanning electron microscope image of porous carbon from the present invention;

[0032] Figure 9 This is a scanning electron microscope image of C / Fe3O4 of the present invention;

[0033] Figure 10 This is a scanning electron microscope image of C / Fe3O4-CH=CH2 of the present invention;

[0034] Figure 11 This is a scanning electron microscope image of the CMPP of the present invention;

[0035] Figure 12This is a scanning electron microscope image of the MPCNP1 of the present invention;

[0036] Figure 13 This is a scanning electron microscope image of the MPCNP2 of the present invention. Detailed Implementation

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] To better understand the present invention, the above content will be described in detail below with reference to specific embodiments.

[0039] Please see the appendix Figure 1 -Appendix Figure 13 ;

[0040] Example 1

[0041] This invention provides a method for preparing a magnetic porous nanopolymer that adsorbs polychlorinated biphenyl (PCB) contaminants. The method includes the following steps:

[0042] Step a, Preparation of magnetic porous carbon (C / Fe3O4):

[0043] 2g of unsaturated polyester resin was weighed into a porcelain crucible and heated to 200℃ at 5℃ / min and held for 2h for carbonization. The resulting product was rapidly mixed with solid urea (mass ratio 2:1) and ground into powder. The powder was then placed in a tube furnace and heated to 1000℃ at 5℃ / min under a nitrogen atmosphere and continued to burn for 2h to obtain porous nitrogen carbide material.

[0044] 0.35 g of PC material was ultrasonically dispersed in 350 mL of water for 30 min to obtain a porous nitrogen carbon solution with a concentration of 1.0 mg / mL. 4.0 g of FeCl2·4H2O and 10.9 g of FeCl3·6H2O were added, and the solution was dissolved by mechanical stirring while simultaneously purging with nitrogen for 20 min. After stopping the nitrogen purging, stirring was continued, and the solution was heated to 70 °C. 30% concentrated ammonia was added dropwise to adjust the pH of the solution to approximately 11. The reaction was maintained at this temperature for 6 h, then cooled to room temperature. Solid-liquid separation was performed for 10 min using a magnet close to the bottom. The solution was washed multiple times with water and ethanol, and then vacuum dried at 60 °C for 12 h to obtain C / Fe3O4.

[0045] Step b, Preparation of ethylene-functionalized magnetic porous carbon (C / Fe3O4-CH=CH2):

[0046] 1.0 g of magnetic porous carbon (C / Fe3O4) nanomaterial was weighed and placed in a three-necked flask containing 150 mL of dimethylformamide (DMF). The solution was sonicated for 15 min to uniformly disperse C / Fe3O4 in the solvent, forming a suspension. 2 g of triethylamine (TEA) was added dropwise to the suspension as an acid-binding agent, and nitrogen gas was purged for 15 min to remove oxygen. 7 mL of a mixture of acryloyl chloride and DMF (volume ratio 1:1) was placed in a constant-pressure dropping funnel and added dropwise to the magnetic porous carbon nanomaterial solution at a rate of 5 drops per 5 seconds under ice-water bath conditions (0-5℃). After the addition was complete, the reaction was continued at low temperature for half an hour, then transferred to room temperature for 2 h. Finally, the mixture was filtered, and washed repeatedly with water and DMF alternately to remove triethylamine hydrochloride and some cross-linking products. The mixture was then vacuum dried at 60℃ for 12 h to obtain C / Fe3O4-CH=CH2.

[0047] Step c: Preparation of magnetic porous cyclodextrin nanopolymers (MPCNP) and magnetic porous carbon polymers (MCPP):

[0048] In a beaker, add 20 mL of water, 10 mg of potassium persulfate, 0.5 g of sodium sulfite, and 1.2 g of cyclodextrin, and stir until homogeneous to obtain an aqueous solution. In a round-bottom beaker, add 1 g of ethylene-functionalized magnetic porous carbon (C / Fe3O4-CH=CH2), 0.25 g of acrylamide, and 5 mL of ethylene glycol dimethacrylate crosslinking agent. While maintaining a total oil phase volume of 10 mL, control different toluene to Span 80 feed ratios to achieve Span 80 mass percentages of 5, 10, 20, and 35 wt% in the oil phase. Heat the four mixtures to 65 °C and mechanically stir at 500 rpm for 15 minutes to obtain an oil phase solution.

[0049] 20 mL of the aqueous phase was slowly added dropwise to the oil phase solution at a rate of 1 mL / min using a dropper. After the addition was complete, stirring was continued for 30 minutes. The experiment showed that the 35 wt% emulsion was a yellowish-brown viscous mud-like substance, while the rest was a viscous emulsion. To study the effect of oil phase concentration on the preparation of the adsorbent material, polymers with oil phase concentrations of 5 wt% and 35 wt% were selected for the study and named MPCNP1 and MPCNP2, respectively. After reacting the emulsions in a vacuum oven at 60 °C for 24 hours, the polymers were crushed and washed 3-5 times alternately with hot water (80 °C) and ethanol to remove oil and surfactants from the precipitate surface. Then, Soxhlet extraction was performed for 12 hours with ethanol and ethanol-acetic acid solution (volume ratio = 8:2), followed by vacuum drying at 60 °C for 12 hours to obtain the final product.

[0050] Example 2

[0051] This invention provides a method for preparing a magnetic porous nanopolymer that adsorbs polychlorinated biphenyl (PCB) contaminants. The method includes the following steps:

[0052] Based on the steps of Example 1, without adding cyclodextrin material, MCPP was prepared according to an emulsion formulation of 5 wt% oil phase.

[0053] Comparative Experiment 1: Selective Adsorption Performance Test

[0054] Experimental Objective

[0055] This experiment aims to verify whether the magnetic porous cyclodextrin nanopolymers (MPCNP1 and MPCNP2) prepared in this invention exhibit selectivity in adsorbing polychlorinated biphenyls (PCBs) compared to magnetic porous carbon polymers (MCPP) without cyclodextrin. The role of the cyclodextrin functional group is demonstrated by directly comparing the recovery rates of the three materials for various PCBs. Simultaneously, the performance of MPCNP1 and MPCNP2 is compared to determine the optimal material preparation conditions.

[0056] Experimental materials and equipment

[0057] Adsorbent materials:

[0058] Magnetic porous cyclodextrin nanopolymer MPCNP prepared in Example 1 1( The oil phase contains 5 wt% Span 80;

[0059] Magnetic porous cyclodextrin nanopolymer MPCNP prepared in Example 1 2( The oil phase contains 35 wt% Span 80;

[0060] Example 2: Magnetic porous carbon polymer MCPP (without cyclodextrin);

[0061] Experimental steps

[0062] Solution preparation: The mixed standard stock solutions of 8 PCBs were diluted with deionized water to prepare mixed PCBs working solutions with an initial concentration (c0) of 1000 μg / L.

[0063] Sample preparation: Accurately weigh 30.0 mg (dry weight) of MPCNP1, MPCNP2 and MCPP powder respectively, and place each in a clean 100 mL Erlenmeyer flask. Set up 3 parallel samples for each sample.

[0064] Adsorption process: Accurately add 10.0 mL of the above-prepared PCBs working solution to each conical flask containing the adsorbent material.

[0065] Oscillating adsorption: Place all conical flasks in a constant temperature shaker and shake at 100 rpm for 30 minutes at a constant temperature of 25°C to complete the adsorption process.

[0066] Magnetic separation: After oscillation, a strong magnet is placed firmly against the bottom of each conical flask. After standing for 5 minutes, once the magnetic polymer that has adsorbed the PCBs is completely adsorbed to the bottom of the flask, the supernatant (i.e., the aqueous solution after adsorption) is removed.

[0067] Elution / Extraction: Transfer all the magnetically separated solid-phase product (adsorbent) to 50 mL centrifuge tubes. Add 10.0 mL of n-hexane to each centrifuge tube as the eluent.

[0068] Vortex elution: Use a vortex mixer to vortex the solid-liquid mixture in the centrifuge tube for 2 minutes to ensure that the PCBs are fully eluted from the adsorbent into hexane.

[0069] Sample analysis: The vortexed hexane extract was transferred to a vial and analyzed by GC-MS or GC-ECD to determine the specific concentration (c1) of the eight polychlorinated biphenyls.

[0070] Calculation method: The recovery rate (E) is calculated according to the following formula based on the concentration of PCBs in the extraction solution (c1) and the initial concentration of the solution before adsorption (c0 = 1000 μg / L).

[0071] E = (c1 / c0) × 100%;

[0072] The calculated recovery rates are shown in the attached figure. Figure 1 As shown;

[0073] Experimental summary, as per appendix Figure 1 It can be known that:

[0074] The material prepared by this invention exhibits significant adsorption selectivity;

[0075] Selectivity Source Validation: Comparing the three materials, MPCNP1 and MPCNP2 showed high recoveries of PCB118, PCB153, PCB138, and PCB180, while MCPP showed low recoveries of all PCBs. Specifically, MPCNP1 achieved recoveries of 88.2% and 89.1% for PCB118 and PCB153, respectively, which were 8.8% and 10.6% higher than those of MCPP. This result confirms that the selectivity of the materials originates from the cyclodextrin functional groups grafted into the polymer network, which specifically recognize and adsorb PCB molecules with specific structures through host-guest inclusion interactions.

[0076] Preparation condition optimization: By comparing MPCNP1 and MPCNP2, it was found that MPCNP1 (prepared from 5 wt% Span 80) had higher recoveries of PCB118, PCB153, PCB138, and PCB180 than MPCNP2 (prepared from 35 wt% Span 80). This indicates that a lower emulsifier concentration is beneficial for forming a more optimized pore structure or functional group distribution, thereby obtaining a stronger selective adsorption effect.

[0077] Conclusion: This comparative experiment successfully demonstrated the technical advantages of the method of the present invention.

[0078] Comparative Experiment 2: Static Adsorption Isotherm Analysis

[0079] Comparative Experiment 2: Static Adsorption Isotherm Analysis

[0080] 1. Experimental Objective

[0081] This experiment aims to quantitatively evaluate the adsorption capacity of the optimal-performing MPCNP1 material for polychlorinated biphenyls (PCBs). Adsorption isotherms were plotted by measuring data from PCB solutions of different initial concentrations after reaching adsorption equilibrium with MPCNP1 at a constant temperature, and the experimental data were fitted using Langmuir and Freundlich models. This process aims to determine the theoretical maximum adsorption capacity (Qm), adsorption affinity, and characteristics of the adsorption process, and to compare the performance with published adsorption materials to verify the superiority of the material of this invention.

[0082] 2. Experimental Materials and Equipment

[0083] Adsorbent material: MPCNP1, prepared in Example 1 and selected in Comparative Experiment 1;

[0084] Reagents: Mixed standard stock solution of 8 polychlorinated biphenyls (PCBs); deionized water;

[0085] Main equipment: 50mL stoppered conical flasks or centrifuge tubes; analytical balance (accuracy 0.1mg); constant temperature shaker; strong magnet; pipettes and tips; gas chromatography-mass spectrometry (GC-MS) or gas chromatography-electron capture detector (GC-ECD);

[0086] 3. Experimental Procedure

[0087] Series of solutions preparation: Eight PCBs mixed standard stock solutions were serially diluted with deionized water to prepare a series of PCBs mixed working solutions with initial concentrations (Co) of 1, 5, 10, 20, 30, 40, and 50 mg / L.

[0088] Sample preparation: Accurately weigh 10.0 mg of MPCNP1 powder and place it into a set of clean 50 mL stoppered conical flasks. Set up 3 parallel samples for each concentration point.

[0089] Adsorption process: 10.0 mL of PCBs working solution with different initial concentrations was accurately added to each conical flask containing MPCNP1.

[0090] Oscillation equilibrium: Place all conical flasks in a constant temperature shaker and oscillate at 100 rpm for 30 minutes at a constant temperature of 25°C to ensure that adsorption reaches equilibrium.

[0091] Magnetic separation: After oscillation, a strong magnet is used to separate the solid and liquid in the conical flask.

[0092] Sample analysis: Carefully aspirate the supernatant and use GC-MS or GC-ECD to determine the concentration of each polychlorinated biphenyl in the solution after adsorption equilibrium. This is the equilibrium concentration (Ce).

[0093] 4. Data Recording and Analysis

[0094] Equilibrium adsorption capacity calculation: Based on the measured initial concentration (Co) and equilibrium concentration (Ce), as well as the solution volume V (0.01 L) and adsorbent mass m (0.01 g), the equilibrium adsorption capacity Qe (mg·g) is calculated using the following formula. -1) :

[0095] Qe=(Co-Ce)×V / m

[0096] Isotherm model fitting: The calculated series of (Ce,Qe) data points are substituted into the nonlinear equations of the Langmuir model and the Freundlich model for fitting analysis.

[0097] Langmuir model:

[0098] Qe=(Qm×KL×Ce) / (1+KL×Ce)

[0099] By fitting the data, the theoretical maximum adsorption capacity Qm (mg·g) was obtained. -1) Langmuir adsorption constant KlL (L·mg) -1) and correlation coefficient R 2 .

[0100] Freundlich model:

[0101] Qe = K p ×Ce 1 / n By fitting, the Freundlich constant K is obtained. p (mg·g -1)·(L·mg -1 ) 1 / n Adsorption strength parameter n and correlation coefficient R 2 .

[0102] The fitted curve data for MPCNP1 are shown in the table below:

[0103]

[0104]

[0105] and:

[0106] The Langmuir fitting curve of MPCNP1 is shown in the figure below. Figure 2 As shown;

[0107] The Freundlich fitting curve of MPCNP1 is shown in the figure below. Figure 3 As shown;

[0108] 5. Experiment Summary

[0109] Model fitting analysis of static adsorption data showed that the MPCNP1 material prepared in this invention has excellent adsorption performance.

[0110] Analysis using the Langmuir model revealed the maximum adsorption capacity Qm (mg·g) of PCB138. -1) Reaching 954.63 mg / g indicates its extremely high adsorption capacity, while the adsorption strength constant of PCB118, KL (L·mg), is... -1) The concentration was 0.213 L / mg, indicating strong adsorption affinity. The Freundlich model further revealed the heterogeneity of the adsorption process, and the K0.05 of PCB28... p (mg 1-1 / n ·L 1 / n ·g -1 The adsorption value is 69.50, but its adsorption strength parameter n = 0.5035 < 1, indicating that the adsorption process is an easily carried out nonlinear adsorption.

[0111] Comparison with existing technologies: A horizontal comparison of the adsorption performance of this invention with publicly available literature data highlights its advantages. For example, Llorca M et al. reported a maximum adsorption capacity of 755.27 mg·g for PCB28. -1 (Fitted by Freundlich model) The maximum adsorption capacity of PCB153 reported by Wang et al. was 794 mg / g (fitted by Langmuir model). In comparison, the MPCNP1 material prepared in this invention exhibits a higher level of adsorption capacity, which directly proves the advancement and superiority of the technical solution of this invention.

[0112] Comparative Experiment 3: Adsorption Kinetics Analysis

[0113] 1. Experimental Objective

[0114] This experiment aims to investigate the adsorption rate of polychlorinated biphenyls (PCBs) on the MPCNP1 material prepared in this invention, determine the time required for adsorption to reach equilibrium, and reveal the controlling mechanism of the adsorption process through kinetic model fitting. By comparing the goodness of fit of the pseudo-first-order kinetic model and the pseudo-second-order kinetic model, it is determined whether the adsorption process is dominated by physisorption or chemisorption, thereby providing a theoretical basis for the practical application of the material.

[0115] 2. Experimental Materials and Equipment

[0116] Adsorbent materials:

[0117] The MPCNP1 prepared in Example 1 and selected in Comparative Experiment 1

[0118] Main equipment:

[0119] 250mL stoppered conical flask; analytical balance (accuracy 0.1mg); constant temperature shaker; strong magnet; pipette and tips; stopwatch or timer; gas chromatography-mass spectrometry (GC-MS) or gas chromatography-electron capture detector (GC-ECD);

[0120] 3. Experimental Procedure

[0121] Solution and Adsorbent Preparation: Prepare a working solution with an initial concentration (Co) of 50 mg / L using deionized water from the PCBs mixed standard stock solution. Accurately weigh 50.0 mg of MPCNP1 powder and place it in a clean 250 mL stoppered conical flask.

[0122] Initiate adsorption: Accurately add 50.0 mL of the above-prepared PCBs working solution to the conical flask, immediately tighten the stopper and start timing (t = 0), and at the same time place the conical flask in a constant temperature shaker and continuously shake at 100 rpm at 25°C.

[0123] Timed sampling: At preset time points of 1, 2, 3, 4, 5, 10, 15, and 30 minutes, approximately 1.5 mL of suspension was quickly taken from the conical flask.

[0124] Sample separation: The extracted sample is immediately separated magnetically using a strong magnet to quickly separate the solid-phase adsorbent from the liquid phase and terminate the adsorption reaction of the sample.

[0125] Sample analysis: The supernatant after separation was taken and analyzed by GC-MS or GC-ECD to determine the concentration (Ct) of the remaining PCBs in the solution at different time points t.

[0126] 4. Data Recording and Analysis

[0127] Instantaneous adsorption capacity calculation: Based on the initial concentration (Co), the concentration at different time points (Ct), the solution volume V (0.05 L), and the adsorbent mass m (0.05 g), the adsorption capacity qt (mg·g) at time t is calculated using the following formula. -1 ):

[0128] qt=(Co-Ct)×V / m

[0129] Dynamic model fitting: Substitute the calculated series of (t, qt) data points into the linear equations of the pseudo-first-order and pseudo-second-order dynamic models respectively for fitting.

[0130] Pseudo-first-order dynamics model:

[0131] log(qe-qt)=log(q)-(k1 / 2.303)×t

[0132] The model obtains the quasi-first-order rate constant k1(min) by linearly fitting a graph of log(q-qt) to t. -1 ) and equilibrium adsorption capacity qe (mg·g -1 ).

[0133] Pseudo-second-order model:

[0134] t / qt=(1 / (k2×qe 2 ))+(1 / qe)×t

[0135] The model obtains the quasi-second-order rate constant k2 (g·mg) by performing linear fitting on a graph of t / qt versus t. -1 ·min -1 ) and equilibrium adsorption capacity qe (mg·g -1 ).

[0136] The pseudo-first-order and pseudo-second-order dynamic data of MPCNP1 are shown in the table below:

[0137]

[0138]

[0139] and:

[0140] A schematic diagram of the pseudo-first-order dynamic fitting of MPCNP1 is shown below. Figure 4 As shown;

[0141] A schematic diagram of the pseudo-second-order dynamic fitting of MPCNP1 is shown below. Figure 5 As shown;

[0142] Experiment Summary:

[0143] The adsorption capacity increases rapidly in the 0-5 minute period, while the increase is not significant in the 5-10 minute period, indicating that the adsorption tends to reach equilibrium. Meanwhile, the kinetic model fit confirms the pseudo-second-order kinetic model (R0). 2 A value >0.998 is more suitable for describing the adsorption process, and its fitting results support the dominance of the chemisorption mechanism. Furthermore, combined with the changes in the functional groups on the adsorbent surface from previous FTIR analyses, it indicates that adsorption involves electron transfer or chemical bonding, confirming that these functional groups form chemisorption with PCB molecules through hydrogen bonds or π-π interactions. This further verifies the interaction between the functional groups and PCB molecules.

[0144] Comparative Experiment 4: Reusability Test

[0145] 1. Experimental Objective

[0146] This experiment aims to evaluate the reusability and operational stability of the top-performing MPCNP1 material. By continuously performing multiple adsorption-desorption cycles and detecting the change in the material's recovery rate of PCBs after each cycle, its durability, stability, and economic feasibility in practical applications are verified.

[0147] 2. Experimental Materials and Equipment

[0148] Adsorbent materials:

[0149] MPCNP1, prepared in Example 1 and selected in Comparative Experiment 1;

[0150] Reagents and solutions:

[0151] PCBs mixed working solution (initial concentration co = 1000 μg / L); n-hexane (chromatographic grade, used as regeneration solvent); ethanol (for cleaning);

[0152] Main equipment:

[0153] 50 mL centrifuge tubes; analytical balance (accuracy 0.1 mg); constant temperature shaker; vortex mixer; strong magnet; pipette and tips; vacuum drying oven; gas chromatography-mass spectrometry (GC-MS) or gas chromatography-electron capture detector (GC-ECD);

[0154] 3. Experimental Procedure

[0155] The experiment consists of 10 consecutive "adsorption-regeneration" cycles.

[0156] First adsorption (1st cycle):

[0157] Accurately weigh 30.0 mg of MPCNP1 powder and place it in a 50 mL centrifuge tube.

[0158] Add 10.0 mL of PCBs mixed working solution.

[0159] Adsorption was completed by shaking at 25°C for 30 minutes.

[0160] Initial regeneration and recovery rate determination:

[0161] A powerful magnet was used to separate the adsorbed saturated MPCNP1 from the water.

[0162] Add 10.0 mL of n-hexane to the centrifuge tube containing moistened MPCNP1.

[0163] Use a vortex mixer to vortex oscillate for 2 minutes to desorb the PCBs from the MPCNP1.

[0164] The hexane desorption solution was analyzed by GC-MS to determine the concentration of PCBs and the recovery rate of the first cycle was calculated accordingly.

[0165] Material preparation and the next cycle:

[0166] MPCNP1 and n-hexane were separated using a magnet.

[0167] MPCNP1 was washed twice with ethanol to remove residual n-hexane and contaminants.

[0168] After cleaning, MPCNP1 was dried in a vacuum oven at 60°C for 2 hours for future use.

[0169] Repeat loop:

[0170] Use the dried MPCNP1 for the next adsorption experiment, and repeat steps 1 to 3 in complete order.

[0171] This process is repeated a total of 10 times, and the recovery rate of each iteration is recorded.

[0172] 4. Data Recording and Calculation

[0173] Calculation method: The recovery rate for each cycle is calculated using the following formula:

[0174] Recovery rate (%) = (Mass of PCBs in n-hexane after desorption / Initial total mass of PCBs in aqueous solution before adsorption) × 100%

[0175] Data recording: The recovery rate data obtained from each cycle were organized and plotted into a bar chart, as shown in the attached figure. Figure 6As shown, this visually illustrates the trend of recycling rate changes with the number of reuses.

[0176] 5. Experiment Summary

[0177] From the appendix Figure 6 The results of this experiment fully demonstrate that the MPCNP1 material has good stability and reusability.

[0178] High stability: Experimental results show that after 5 uses, the material still maintains a recovery rate of over 80% for various PCBs. This proves that the MPCNP1 adsorbent prepared in this invention has stable performance and can be effectively reused at least 5 times while maintaining high selectivity and high recovery rate.

[0179] Performance degradation analysis: When the number of reuses increased to 10 times, a significant performance degradation was observed, with the overall recovery rate decreasing by 5% to 12%, and the selectivity of the material also decreased to some extent.

[0180] The degradation mechanism is inferred to be primarily due to physical losses during the regeneration process. During each vortex elution with n-hexane, the high-speed shear force may cause some cyclodextrin molecules grafted onto the polymer surface to detach. Since cyclodextrins are key active sites for selective adsorption, their reduction directly leads to a decrease in the overall recovery capacity and selectivity of the material.

[0181] Conclusion: Although performance declined after multiple cycles, MPCNP1 maintained high adsorption efficiency even after repeated use. Overall, this material exhibits excellent regeneration capability and operational stability, demonstrating its significant potential as an economical and efficient adsorbent in environmental remediation.

Claims

1. A method for preparing a magnetic porous nanopolymer for adsorbing polychlorinated biphenyl (PCB) contaminants, characterized in that, Includes the following steps: Step a, Preparation of magnetic porous carbon: Carbonize unsaturated polyester resin and react it with urea to obtain porous carbon material. Then, load iron oxide onto the porous carbon material to obtain magnetic porous carbon. Step b, Ethylene functionalization: The magnetic porous carbon is reacted with a vinyl-containing reagent to graft vinyl functional groups onto the surface of the magnetic porous carbon, thereby obtaining ethylene-functionalized magnetic porous carbon. Step c, polymerization reaction: Using the emulsion template method, an aqueous solution containing cyclodextrin and an oil solution containing the ethylene-functionalized magnetic porous carbon, polymeric monomers and crosslinking agents are prepared. The aqueous solution and the oil solution are mixed to form an emulsion and then polymerized. After purification, the polymerized product is obtained as the magnetic porous nanopolymer.

2. The method for preparing a magnetic porous nanopolymer for adsorbing polychlorinated biphenyl (PCB) contaminants according to claim 1, characterized in that, The loaded iron oxide in step a is generated by adding ferrous salt and ferric salt to an aqueous solution of porous carbon material and reacting them under inert gas protection.

3. The method for preparing a magnetic porous nanopolymer for adsorbing polychlorinated biphenyl (PCB) contaminants according to claim 2, characterized in that, The ferrous salt is ferrous chloride tetrahydrate, and the ferric salt is ferric chloride hexahydrate.

4. The method for preparing a magnetic porous nanopolymer for adsorbing polychlorinated biphenyl (PCB) contaminants according to claim 1, characterized in that, The vinyl-containing reagent in step b is acryloyl chloride, and the reaction is carried out in a dimethylformamide solvent in the presence of triethylamine.

5. The method for preparing a magnetic porous nanopolymer for adsorbing polychlorinated biphenyl (PCB) contaminants according to claim 1, characterized in that, The emulsion template method described in step c is the concentrated emulsion template method.

6. The method for preparing a magnetic porous nanopolymer for adsorbing polychlorinated biphenyl (PCB) contaminants according to claim 5, characterized in that, The aqueous solution in the step comprises water, cyclodextrin, and potassium persulfate as an initiator.

7. The method for preparing a magnetic porous nanopolymer for adsorbing polychlorinated biphenyl (PCB) contaminants according to claim 1, characterized in that, In the aforementioned steps, the components of the oil phase solution include: ethylene-functionalized magnetic porous carbon, acrylamide as a polymerization monomer, ethylene glycol dimethacrylate as a crosslinking agent, and Span 80 as an emulsifier.

8. The method for preparing a magnetic porous nanopolymer for adsorbing polychlorinated biphenyl (PCB) contaminants according to claim 1, characterized in that, The polymerization reaction is carried out at a temperature of 50-70°C for 20-30 hours.

9. The method for preparing a magnetic porous nanopolymer for adsorbing polychlorinated biphenyl (PCB) contaminants according to claim 1, characterized in that, In step c, the purification process includes washing the polymerization product with hot water, ethanol, and ethanol-acetic acid solution in sequence, followed by Soxhlet extraction.

10. The method for preparing a magnetic porous nanopolymer for adsorbing polychlorinated biphenyl (PCB) contaminants according to claim 1, characterized in that, The magnetic porous nanopolymer is used to adsorb PCBs.

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