An imidazole / pyridine bis-onium salt organic polymer adsorbent and a preparation method and application thereof

Abstract

The application discloses an imidazole / pyridine bis-onium salt organic polymer adsorbent and a preparation method and application thereof. The organic polymer adsorbent comprises imidazole onium salt groups and pyridine onium salt groups, has a mesoporous and positive charge structure, and exhibits swelling characteristics in an aqueous solution, and the surface always maintains positive electricity, and through electrostatic interaction, ion exchange and pi-pi stacking, exhibits excellent adsorption performance on anionic pollutants such as diclofenac sodium and methyl orange. At 298 K, the maximum adsorption capacity of the material on the diclofenac sodium and the methyl orange can be up to 1214.89 mg / g and 1227.06 mg / g respectively. The material has a simple preparation method, can maintain high adsorption efficiency in a wide pH range and a complex water environment, and has a wide application prospect in the field of anionic pollutant removal.

Description

Technical Field

[0001] This invention relates to the fields of environmental functional materials and water treatment technology, specifically to an imidazole / pyridine bisium salt organic polymer adsorbent, its preparation method, and its application. Background Technology

[0002] With global industrialization and population growth, water pollution has become an increasingly serious problem. Pharmaceuticals and personal care products (PPCPs) and synthetic dyes are of particular concern due to their potential ecotoxicity and health risks. Diclofenac sodium (DS), a common nonsteroidal anti-inflammatory drug, and methyl orange (MO), a typical anionic azo dye, are two common anionic organic pollutants in water bodies. They not only harm aquatic ecosystems but may also affect human health through the food chain.

[0003] Currently, methods for treating such organic pollutants include advanced oxidation, membrane separation, biodegradation, and adsorption. Among these, adsorption is one of the most promising methods due to its simplicity, low cost, high efficiency, and low risk of secondary pollution. Common adsorbents such as activated carbon and resins have limitations, including limited adsorption capacity, difficulty in regeneration, and lack of selective adsorption for specific anionic pollutants. Especially under alkaline conditions, their negative surface charge makes it difficult to effectively capture anionic organic pollutants.

[0004] Cationic polymers, based on electrostatic / ion exchange mechanisms, have shown great potential in removing anionic pollutants. However, these materials often suffer from overly dense polymerization, leading to limited pore size and volume, which hinders mass transfer processes and affects their practical applications. Therefore, developing novel cationic adsorbents with high adsorption capacity and rapid mass transfer rates is a pressing technical problem in this field. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to provide an imidazole / pyridine bisium salt organic polymer adsorbent, its preparation method, and its application, in order to solve the problems of low adsorption capacity, slow mass transfer rate, poor adsorption stability, and intolerance to alkaline and high-salt environments that exist in the prior art when cationic polymers remove anionic pollutants from water.

[0006] To achieve the above objectives, a first aspect of the present invention provides an imidazole / pyridine bisium salt organic polymer adsorbent comprising imidazole bisium salt groups and pyridine bisium salt groups, having a mesoporous and positively charged structure, and exhibiting swelling properties in aqueous solution.

[0007] Furthermore, the organic polymer adsorbent is prepared by quaternization polymerization of 1,3,5-triimidazolylbenzene and 1-(3,5-bis(bromomethyl)benzyl)pyridine-1-onium. The pyridine-onium salt group effectively reduces the active sites of the reaction, prevents the formation of a dense structure, and promotes the formation of a mesoporous structure. Simultaneously, the pyridine-onium salt group ensures the positive charge density of the polymer and provides pyridine rings that can form π-π stacking with aromatic pollutants. This material can swell in aqueous solution, significantly increasing its network porosity, which both promotes the internal diffusion of pollutants and improves the accessibility of internal sites.

[0008] Furthermore, the organic polymer adsorbent is used to adsorb anionic pollutants in aqueous solution.

[0009] Secondly, the present invention also provides a method for preparing the imidazole / pyridine bis-onium salt organic polymer adsorbent, comprising: placing 1-(3,5-bis(bromomethyl)benzyl)pyridine-1-onium and 1,3,5-triimidazolebenzene in a high-pressure reactor, adding a reaction solvent, stirring to dissolve, sealing, reacting at 120~180 °C for 24~48 hours, cooling, filtering, washing and drying to obtain the imidazole / pyridine bis-onium salt organic polymer.

[0010] Furthermore, the preparation method further includes: Preparation of intermediate 1,3,5-triimidazolylbenzene: 1,3,5-tribromobenzene, imidazole, potassium carbonate and anhydrous copper sulfate were placed in a high-pressure reactor and heated to 160-200 °C under nitrogen atmosphere. After washing, dissolving, filtering and precipitation, the 1,3,5-triimidazolylbenzene was obtained by drying.

[0011] Furthermore, the preparation method further includes: Preparation of intermediate 1-(3,5-bis(bromomethyl)benzyl)pyridine-1-onium: Pyridine and 1,3,5-tris(bromomethyl)benzene were added to an acetone solution and stirred at room temperature. The reaction was then carried out by filtration, washing and drying to obtain the 1-(3,5-bis(bromomethyl)benzyl)pyridine-1-onium.

[0012] Furthermore, the molar ratio of 1,3,5-tribromobenzene, imidazole, potassium carbonate, and anhydrous copper sulfate is 18.4:110.5:73.7:0.92, and the heating reaction time is 12-48 hours.

[0013] Furthermore, the molar ratio of pyridine to 1,3,5-tris(bromomethyl)benzene is 1.3:1.4, and the reaction time is 10-24 hours with stirring at room temperature.

[0014] Further, the molar ratio of 1-(3,5-bis(bromomethyl)benzyl)pyridine-1-onium to 1,3,5-triimidazolylbenzene is (1~3):(1~2).

[0015] Thirdly, the present invention also provides an application of the imidazole / pyridine bisium salt organic polymer adsorbent described above or the imidazole / pyridine bisium salt organic polymer adsorbent prepared by the above preparation method in adsorbing anionic pollutants in aqueous solution.

[0016] Furthermore, the anionic contaminant is diclofenac sodium or methyl orange.

[0017] Furthermore, the organic polymer maintains a positive charge on its surface throughout a wide pH range (pH=2-12), exhibiting excellent adsorption performance for DS and MO.

[0018] The adsorption mechanisms mainly include: electrostatic interactions and ion exchange between anions and positively charged imidazolium / pyridinium salt sites in the material, as well as π-π stacking interactions between polymer aromatic rings and pollutant aromatic rings, specifically including: the C=N cations of imidazolium salts in IP-COP. + With DS's COO - or MO-SO3 - There is a strong electrostatic attraction between them; free Br in IP-COP - With -COO - or -SO3 - Ion exchange occurred between them; π-π stacking interactions occurred between the IP-COP aromatic structure and the benzene ring of DS or MO.

[0019] The principle of this invention lies in constructing an adsorption material with both mesoporous properties and a permanent positive charge through a functional group regulation strategy in monomers. The specific steps are as follows: First, using pyridine and 1,3,5-tris(bromomethyl)benzene as raw materials, a nucleophilic substitution reaction is used to synthesize 1-(3,5-bis(bromomethyl)benzyl)pyridine-1-onium monomer. The core function of this step is to transform the original tridentate node (1,3,5-tris(bromomethyl)benzene) into a bidentate node, while simultaneously introducing a positively charged pyridineonium salt group. Subsequently, the obtained bidentate monomer and the tridentate node 1,3,5-triimidazolylbenzene are copolymerized through a quaternization reaction, successfully constructing a permanently positively charged mesoporous organic polymer—quaternized poly(1,3,5-triimidazolylbenzene-co-1-(3,5-bis(bromomethyl)benzyl)pyridine-1-onium) (abbreviated as IP-COP). The key mechanism of this design lies in transforming the tridentate nodes (1,3,5-tris(bromomethyl)benzene) into bidentate nodes, effectively reducing the spatial crosslinking density of the polymer network and avoiding dense packing, thereby inducing the formation of mesoporous structures. Simultaneously, the densely distributed and permanently fixed pyridinium salt cations in the polymer backbone endow the material with strong electrostatic affinity. Based on these structural advantages, IP-COP can serve as a highly efficient adsorbent, achieving rapid and efficient capture and removal of anionic pollutants in aqueous phases through its mesoporous structure and electrostatic interactions.

[0020] Beneficial effects: Compared with the prior art, the present invention has the following significant beneficial effects: (1) Structural innovation and mesoporous regulation: The present invention designs an imidazole / pyridine bis-onium salt cationic polymer (IP-COP), whose skeleton contains both imidazole onium salt and pyridine onium salt cationic groups. By utilizing the synergistic mechanism of the bis-onium salt cationic groups, a mesoporous structure with a cationic aromatic skeleton is formed, realizing the efficient adsorption of aromatic anionic pollutants DS and MO. Among them, the imidazole onium salt group constitutes the main cationic skeleton, while the pyridine onium salt group not only effectively increases the positive charge density of the material and provides additional adsorption sites, but also acts as a "spatial spacer" group during the polymerization process, significantly reducing the cross-linking density and promoting the formation of mesoporous structure, thereby improving the mass transfer and diffusion dynamics of pollutant molecules. (2) Ultra-high adsorption capacity: Under the condition of 298 K, the maximum adsorption capacity of IP-COP for DS and MO is as high as 1214.89 mg / g and 1227.06 mg / g, respectively, which is significantly better than many MOF derivatives, biochar and other adsorption materials, showing extremely strong adsorption potential. (3) Good renewability and chemical stability: After 5 adsorption-desorption cycles, the adsorption capacity of IP-COP for DS and MO can still maintain 84.42% and 94.33% of the initial values, respectively, indicating that the material has excellent reusability and chemical stability, which is beneficial to long-term operation and economy in practical engineering applications. (4) Wide pH range: Due to the permanently fixed positive charge of onium salt in the polymer, the surface potential of IP-COP remains positive in a wide pH range of 2 to 12, avoiding the decrease in adsorption performance caused by surface charge reversal or neutralization under alkaline conditions of traditional adsorbents. The chemical structure of this material is stable in this pH range, and the removal rate of anionic diclofenac sodium (DS) and methyl orange (MO) is minimally affected by the environmental pH and salt concentration, ensuring adsorption stability under various actual water quality conditions. (5) Excellent anti-interference ability: In high salinity environments (0.1 mol / L NaCl) and in actual water bodies (such as tap water and river water), IP-COP can still maintain stable adsorption efficiency, showing outstanding anti-ion interference ability, and is suitable for the efficient removal of anionic pollutants in complex water quality systems. Attached Figure Description

[0021] Figure 1 A synthesis roadmap for IP-COP; Figure 2 1-(3,5-bis(bromomethyl)benzyl)pyridine-1-onium (BBMPy) +1,3,5-tris(bromomethyl)benzene (TIB), methyl orange (MO), diclofenac (DS), quaternized poly(1-(3,5-bis(bromomethyl)benzyl)pyridin-1-onthium-co-1,3,5-tris(bromomethyl)benzene) (IP-COP) and FTIR spectra of diclofenac (IP-COP@DS) and methyl orange (IP-COP@MO) after adsorption; Figure 3 The adsorption capacity of IP-COP for diclofenac sodium (a) and methyl orange (b) at different initial concentrations is shown in the figure. Figure 4 Zeta potential diagram of IP-COP (a); Effect of pH on IP-COP adsorption of DS and MO (b, c); Effect of different concentrations of NaCl on IP-COP adsorption of DS and MO (d). Figure 5 The graph shows the adsorption of DS and MO by IP-COP in different water bodies. Figure 6 The figure shows the results of the IP-COP cycle regeneration experiment. Detailed Implementation

[0022] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0023] Example 1

[0024] The preparation method of the quaternized polyquaternized poly(1-(3,5-bis(bromomethyl)benzyl)pyridine-1-onium-co-1,3,5-tris(bromomethyl)benzene) (IP-COP) adsorbent is as follows: Synthesis of 1,3,5-triimidazolylbenzene (TIB): 5.80 g (18.4 mmol) of 1,3,5-tribromobenzene, 7.52 g (110.5 mmol) of imidazole, 10.2 g (73.7 mmol) of potassium carbonate, and 0.147 g (0.92 mmol) of anhydrous copper sulfate were weighed and placed in a 100 mL polytetrafluoroethylene-lined reactor. Under a nitrogen atmosphere, the reactor was sealed and heated in an oven at 180 °C for 24 h. After cooling to room temperature, the solid was filtered and thoroughly washed with water. The resulting solid was dissolved in 100 mL of methanol solution, and the dark brown insoluble matter was removed by filtration. Water was then added to the filtrate, resulting in a white precipitate. The solid was collected by suction filtration and dried to obtain the solid product TIB.

[0025] 1-(3,5-bis(bromomethyl)benzyl)pyridine-1-onium (BBMPy) +Synthesis of BBMPy: Pyridine (0.1 mL, 1.3 mmol) and 1,3,5-tris(bromomethyl)benzene (0.4996 g, 1.40 mmol) were added to a round-bottom flask containing 10 mL of acetone solution. The reaction was stirred at room temperature for 12 h, during which a white precipitate formed. After filtration, washing with acetone, and drying, a white solid product BBMPy was obtained. + .

[0026] IP-COP synthesis: combining BBMPy + (0.534 g, 1.5 mmol) and TIB (0.2763 g, 1.0 mmol) were placed in a 100 mL polytetrafluoroethylene-lined high-pressure reactor, and 20 mL of N,N-dimethylacetamide (DMAC) was added. The mixture was ultrasonically stirred until completely dissolved. The reactor was sealed and reacted at 150 °C for 48 h. After cooling to room temperature, the solid was filtered off, washed with DMAC and water, and dried to obtain a white solid product, IP-COP.

[0027] The synthetic route for the (1-(3,5-bis(bromomethyl)benzyl)pyridine-1-onium-co-1,3,5-tris(bromomethyl)benzene) adsorbent is shown in the attached diagram. Figure 1 It uses TIB as a three-tooth node, BBMPy + A porous organic polymer was constructed by a quaternization reaction with two nodes.

[0028] Example 2

[0029] The preparation method of the quaternized polyquaternized poly(1-(3,5-bis(bromomethyl)benzyl)pyridine-1-onium-co-1,3,5-tris(bromomethyl)benzene) (IP-COP) adsorbent is as follows: Synthesis of 1,3,5-triimidazolylbenzene (TIB): 5.80 g (18.4 mmol) of 1,3,5-tribromobenzene, 7.52 g (110.5 mmol) of imidazole, 10.2 g (73.7 mmol) of potassium carbonate, and 0.147 g (0.92 mmol) of anhydrous copper sulfate were weighed and placed in a 100 mL polytetrafluoroethylene-lined reactor. Under a nitrogen atmosphere, the reactor was sealed and heated in an oven at 180 °C for 48 h. After cooling to room temperature, the solid was filtered and thoroughly washed with water. The resulting solid was dissolved in 100 mL of methanol solution, and the dark brown insoluble matter was removed by filtration. Water was then added to the filtrate, resulting in a white precipitate. The solid was collected by suction filtration and dried to obtain the solid product TIB.

[0030] 1-(3,5-bis(bromomethyl)benzyl)pyridine-1-onium (BBMPy) +Synthesis of BBMPy: Pyridine (0.1 mL, 1.3 mmol) and 1,3,5-tris(bromomethyl)benzene (0.4996 g, 1.40 mmol) were added to a round-bottom flask containing 10 mL of acetone solution. The reaction was stirred at room temperature for 12 h, during which a white precipitate formed. After filtration, washing with acetone, and drying, a white solid product BBMPy was obtained. + .

[0031] IP-COP synthesis: combining BBMPy + (0.534 g, 1.5 mmol) and TIB (0.2763 g, 1.0 mmol) were placed in a 100 mL polytetrafluoroethylene-lined high-pressure reactor, and 20 mL of DMAC was added. The mixture was ultrasonically stirred until completely dissolved. The reactor was sealed and reacted at 150 °C for 48 h. After cooling to room temperature, the solid was filtered off, washed with DMAC and water, and dried to obtain a white solid product, IP-COP.

[0032] Example 3

[0033] The preparation method of the quaternized polyquaternized poly(1-(3,5-bis(bromomethyl)benzyl)pyridine-1-onium-co-1,3,5-tris(bromomethyl)benzene) (IP-COP) adsorbent is as follows: Synthesis of 1,3,5-triimidazolylbenzene (TIB): 5.80 g (18.4 mmol) of 1,3,5-tribromobenzene, 7.52 g (110.5 mmol) of imidazole, 10.2 g (73.7 mmol) of potassium carbonate, and 0.147 g (0.92 mmol) of anhydrous copper sulfate were weighed and placed in a 100 mL polytetrafluoroethylene-lined reactor. Under a nitrogen atmosphere, the reactor was sealed and heated in an oven at 180 °C for 24 h. After cooling to room temperature, the solid was filtered and thoroughly washed with water. The resulting solid was dissolved in 100 mL of methanol solution, and the dark brown insoluble matter was removed by filtration. Water was then added to the filtrate, resulting in a white precipitate. The solid was collected by suction filtration and dried to obtain the solid product TIB.

[0034] 1-(3,5-bis(bromomethyl)benzyl)pyridine-1-onium (BBMPy) + Synthesis of BBMPy: Pyridine (0.1 mL, 1.3 mmol) and 1,3,5-tris(bromomethyl)benzene (0.4996 g, 1.40 mmol) were added to a round-bottom flask containing 10 mL of acetone solution. The reaction was stirred at room temperature for 12 h, during which a white precipitate formed. After filtration, washing with acetone, and drying, a white solid product BBMPy was obtained. + .

[0035] IP-COP synthesis: combining BBMPy + (0.534 g, 1.5 mmol) and TIB (0.2763 g, 1.0 mmol) were placed in a 100 mL polytetrafluoroethylene-lined high-pressure reactor, and 20 mL of DMAC was added. The mixture was ultrasonically stirred until completely dissolved. The reactor was sealed and reacted at 160 °C for 36 h. After cooling to room temperature, the solid was filtered off, washed with DMAC and water, and dried to obtain a white solid product, IP-COP.

[0036] The following section describes the structural characterization and test results of the quaternized poly(1-(3,5-bis(bromomethyl)benzyl)pyridine-1-onthium-co-1,3,5-tris(bromomethyl)benzene) prepared in Example 1.

[0037] (1) FTIR Infrared characterization was performed on samples before and after IP-COP adsorption of diclofenac sodium and methyl orange. (See attached image.) Figure 2 The curves in the figure represent: 1-(3,5-bis(bromomethyl)benzyl)pyridine-1-onium (BBMPy) + ), 1,3,5-tris(bromomethyl)benzene (TIB), methyl orange (MO), diclofenac sodium (DS), quaternized poly(1-(3,5-bis(bromomethyl)benzyl)pyridine-1-onthium-co-1,3,5-tris(bromomethyl)benzene) (IP-COP) and adsorbed diclofenac (IP-COP@DS) and methyl orange (IP-COP@MO).

[0038] like Figure 2 As shown, BBMPy + At 3436, 3018, 2968 cm -1 The peaks at these locations correspond to the stretching vibrations of -OH, CH in the aromatic ring, and -CH2- in the water molecule, respectively; 1630 / 1487, 1214 / 1153 cm⁻¹ -1 The peaks at these locations represent C=N. + The stretching vibrations of / C=C and CN, and 548 cm -1 The characteristic peak at that location originates from the C-Br bond.

[0039] The infrared spectrum corresponding to TIB shows: 3428 cm⁻¹ -1 The peak at 3100 cm⁻¹ represents the stretching vibration peak of -OH in water. -1 The nearby peaks are attributed to the CH vibrations of the benzene and imidazole rings, with the skeletal vibrations of the imidazole and benzene rings appearing at 1618 and 1501 cm⁻¹. -1 The stretching vibrations of the CN bond are located at 1255 and 1075 cm⁻¹. -1For IP-COP, 3420, 3080, 1621, 1551 / 1446, 1201 cm -1 The absorption peaks at these locations can be attributed to the stretching vibrations of -OH, CH in the aromatic ring, C=N in the imidazole ring, C=C in the benzene ring, and CN in the water molecule, respectively. Furthermore, the absorption peak at 548 cm⁻¹... -1 The disappearance of the nearby C-Br characteristic peak further confirmed the progress of the quaternization reaction and the synthesis of the target product.

[0040] After adsorbing MO, at 1191 / 1029 (-SO3) - (asymmetric and symmetric stretching vibrations), 1601 (aromatic ring C=C stretching vibration), 1519 (azo bond), 1365 cm⁻¹ -1 The appearance of new absorption peaks or significant enhancement of existing peaks at locations such as (CN stretching vibration) indicates that MO has been successfully adsorbed onto the material surface. Comparison of the spectra before and after adsorption reveals that MO originally located at 1202 and 1040 cm⁻¹... -1 -SO3 at the location - The asymmetric and symmetric stretching vibration peaks were redshifted to 1191 and 1029 cm⁻¹, respectively. -1 Meanwhile, the characteristic peak related to the C=N bond of the imidazole ring in IP-COP was significantly weakened and shifted, while the CN peak shifted from 1201 cm⁻¹ to 1191 cm⁻¹. -1 These spectral changes collectively indicate that -SO3 in MO - Electrostatic interactions were generated between the imidazolium cation in IP-COP and the cation. Furthermore, the C=C vibrational peak of the aromatic ring in IP-COP shifted from 1621 cm⁻¹ to 1601 cm⁻¹. -1 This indicates that there may be π-π stacking interactions between IP-COP and MO molecules.

[0041] After adsorption of DS, at 1575 and 1503 cm⁻¹ -1 (Aromatic ring C=C stretching vibration), 1555 and 1367 cm -1 (Asymmetric and symmetric stretching vibrations of the carboxylate group) and 769 / 747 cm⁻¹ -1 A characteristic absorption peak appeared at the (C-Cl stretching vibration) region, indicating that DS had been successfully adsorbed onto IP-COP. Furthermore, the carboxylic acid peaks of DS were observed at 1557 and 1400 cm⁻¹. -1 Moved to 1555 and 1367 cm -1 The characteristic C=C peaks of the DS benzene ring are located at 1500 and 1453 cm⁻¹. -1 Moved to 1503 and 1450 cm -1 This indicates a π-π stacking interaction between the aromatic rings of both compounds. Simultaneously, the C=N and CN vibrational peaks of the imidazole ring in IP-COP change from 1621 and 1201 cm⁻¹, respectively. -1They were displaced to 1627 and 1195 cm respectively. -1 Furthermore, the peak intensity decreased, which may be due to the electrostatic interaction between the carboxylic acid anion of DS and the imidazolium cation of IP-COP.

[0042] (2) Effect of initial concentration on adsorption Shake 50 mg of IP-COP and 50 mL of diclofenac sodium solution (50, 100, 200, 300, 400, 500, 600, 700, 900, 1100, 1300, 1500 mg / L, T=298 K) or methyl orange solution (500, 600, 700, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400 mg / L, T=298 K) for 12 h, and determine and calculate the adsorption capacity at different initial concentrations.

[0043] Figure 3 The effect of initial concentration on the adsorption of diclofenac sodium and methyl orange by IP-COP is shown in the figure. As can be seen from the figure, the adsorption capacity of IP-COP for diclofenac sodium and methyl orange increases significantly with the increase of initial concentration. At 298 K, as the initial concentration increases from 50 / 500 mg / L to 1500 / 1400 mg / L, the adsorption capacity increases from 49.03 / 499.07 mg / g to 1214.89 / 1277.06 mg / g.

[0044] (3) Tests of the Zeta potential of IP-COP and its adsorption capacity for diclofenac sodium and methyl orange at different pH values like Figure 4 As shown, 50 mg of IP-COP and 50 mL of diclofenac sodium solution (200 mg / L, T=298 K) at different pH values ​​(6-12) or methyl orange solution (500 mg / L, T=298 K) at different pH values ​​(5-12) were shaken for 12 h, and the adsorption capacity at different initial pH values ​​was measured and calculated. Similarly, 200 mg / L of diclofenac sodium and methyl orange were used, and NaCl solid was added to make the NaCl concentration in the solution 0-0.1 mol / L, to study the effect of different NaCl concentrations on adsorption.

[0045] The zeta potential of IP-COP remained positive throughout the pH range of 2–12 (gradually decreasing from +34.0 mV to +7.52 mV). Within the pH range of 6–11, the adsorption capacity of IP-COP for 200 mg / L DS remained between 185.94 and 197.54 mg / g; the adsorption capacity for 500 mg / L MO gradually decreased from 499.79 mg / g to 455.39 mg / g. In the NaCl concentration range of 0–0.1 mol / L, the DS adsorption capacity decreased from 198.29 mg / g to 149.11 mg / g, while the MO adsorption capacity only slightly decreased from 199.36 mg / g to 193.18 mg / g, indicating that the material maintains good adsorption performance even in complex aquatic environments.

[0046] (4) Adsorption of DS and MO by IP-COP in different water bodies Figure 5 The graph shows the adsorption of DS and MO (initial concentration 20 mg / L) by 50 mg IP-COP in 50 mL of different water qualities (deionized water, tap water, and river water). The results show that the adsorption capacity of IP-COP for DS in deionized water, tap water, and river water was 19.23 mg / g, 18.98 mg / g, and 18.81 mg / g, respectively. MO adsorption exhibited extremely high stability in different water qualities: its adsorption capacity in the three water bodies was 19.92 mg / g, 19.91 mg / g, and 19.92 mg / g, respectively, with essentially consistent values. This indicates that the complex components in the water matrix have minimal impact on MO adsorption. This confirms the reliable applicability of IP-COP in practical water treatment.

[0047] (5) IP-COP cycle regeneration experiment IP-COP after DS adsorption: Soaking and desorption in a 0.2 mol / L NaCl-ethanol mixture (volume ratio 3:1); IP-COP after MO adsorption: Soaking and desorption in a 0.5 mol / L NaCl-ethanol mixture (volume ratio 1:1); Desorption relies on ion exchange to replace pollutant anions. After regeneration, filtration, washing, and drying allow for repeated adsorption cycles. Figure 6 As shown, after five cycles, the adsorption capacities of IP-COP for DS and MO remained at 84.42% and 94.33% of their initial values, respectively. This result indicates that IP-COP not only has good adsorption performance but also good reusability.

Claims

1. An imidazole / pyridine bisium salt organic polymer adsorbent, characterized in that, The organic polymer adsorbent contains imidazolium salt groups and pyridinium salt groups, has a mesoporous and positively charged structure, and exhibits swelling properties in aqueous solution.

2. The imidazole / pyridine bisium salt organic polymer adsorbent according to claim 1, characterized in that, It is prepared by quaternization polymerization of 1,3,5-triimidazolylbenzene and 1-(3,5-bis(bromomethyl)benzyl)pyridine-1-onium.

3. The imidazole / pyridine bisium salt organic polymer adsorbent according to claim 1, characterized in that, It is used to adsorb anionic pollutants in aqueous solutions.

4. A method for preparing the imidazole / pyridine bisium salt organic polymer adsorbent according to any one of claims 1-3, characterized in that, Includes the following steps: 1-(3,5-bis(bromomethyl)benzyl)pyridine-1-onium and 1,3,5-triimidazole benzene were placed in a high-pressure reactor, a reaction solvent was added, the mixture was stirred and dissolved, and then sealed. The reaction was carried out at 120-180 °C for 24-48 hours. After cooling, the mixture was filtered, washed and dried to obtain the imidazole / pyridine bis-onium salt organic polymer.

5. The preparation method according to claim 4, characterized in that, Also includes: Preparation of intermediate 1,3,5-triimidazolylbenzene: 1,3,5-tribromobenzene, imidazole, potassium carbonate and anhydrous copper sulfate were placed in a high-pressure reactor and heated to 160-200 °C under nitrogen atmosphere. After washing, dissolving, filtering and precipitation, the 1,3,5-triimidazolylbenzene was obtained by drying.

6. The preparation method according to claim 5, characterized in that, Also includes: Preparation of intermediate 1-(3,5-bis(bromomethyl)benzyl)pyridine-1-onium: Pyridine and 1,3,5-tris(bromomethyl)benzene were added to an acetone solution and stirred at room temperature. The reaction was then carried out by filtration, washing and drying to obtain the 1-(3,5-bis(bromomethyl)benzyl)pyridine-1-onium.

7. The preparation method according to claim 6, characterized in that, The molar ratio of 1,3,5-tribromobenzene, imidazole, potassium carbonate, and anhydrous copper sulfate is 18.4:110.5:73.7:0.92, and the heating reaction time is 12-48 hours; the molar ratio of pyridine to 1,3,5-tris(bromomethyl)benzene is 1.3:1.4, and the stirring reaction time at room temperature is 10-24 hours.

8. The preparation method according to claim 4, characterized in that, The molar ratio of 1-(3,5-bis(bromomethyl)benzyl)pyridine-1-onium to 1,3,5-triimidazolylbenzene is (1~3):(1~2).

9. The application of the imidazole / pyridine bisium salt organic polymer adsorbent according to any one of claims 1-3 or the imidazole / pyridine bisium salt organic polymer adsorbent prepared by any one of claims 4-8 in the adsorption of anionic pollutants in aqueous solution.

10. The application according to claim 9, characterized in that, The anionic contaminant is diclofenac sodium or methyl orange.

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