A degradable cross-linked polymer material for efficient iodine capture and its preparation method and application

Abstract

The application discloses a degradable cross-linked polymer material for efficient iodine capture and a preparation method and application thereof. The polymer material is a polyaldehyde group functionalized reaction monomer prepared by one-pot reaction of a lignin source containing aldehyde group phenolic biomass raw material and cyanuric chloride, and a three-dimensional network polymer formed by polycondensation reaction of the polyaldehyde group functionalized reaction monomer and a multi-functionality mercaptan under acidic conditions, namely, the target polymer material of the application. The material does not contain a heterocyclic aromatic macrocycle, and the synthetic route is simple. The nitrogen, oxygen, sulfur and other multiple heteroatom sites in the polymer network have specific high affinity for iodine vapor and iodine trianion, the adsorption capacity of the material for iodine vapor can be more than 3 times of the mass of the material itself, and the removal rate of low-concentration iodine trianion in water is more than 90%. The raw material of the application is renewable, the process is simple, the material has the characteristics of efficient adsorption, easy recovery and degradability, and is suitable for deep purification of radioactive and industrial iodine-containing waste gas and waste water.

Description

Technical Field

[0001] This invention relates to the fields of advanced materials and environmental pollution control, specifically to a degradable cross-linked polymer material for efficient iodine capture, its preparation method, and its application. Background Technology

[0002] Iodine pollutants in industrial wastewater or exhaust gases, especially those existing as iodine vapor and iodine tri-antions, pose a significant challenge to waste treatment in the pharmaceutical and chemical industries due to their persistent environmental impact, bioaccumulation, radioactive hazards, and high chemical toxicity. These pollutants still pose significant environmental and health risks at low concentrations (ppm), but existing treatment technologies are clearly insufficient in their ability to efficiently and selectively remove them.

[0003] Currently, there are two main types of methods for treating iodine-containing contaminants:

[0004] One method is coagulation and sedimentation. This method causes pollutant flocs to settle by adding reagents. It is effective for high-concentration systems, but it has drawbacks when treating low-concentration iodine pollutants at the ppm level, such as a sharp drop in removal efficiency, large dosage of chemical reagents, generation of a large amount of iodine-containing sludge (which may form secondary radioactive waste), and almost no effect on iodine vapor.

[0005] Second, the adsorption method, whose performance is highly dependent on the adsorption material. Widely used porous adsorbents such as activated carbon, molecular sieves and some synthetic resins mainly rely on physical adsorption or weak chemical action, and generally have the following problems: (1) poor adsorption selectivity, making it difficult to specifically capture iodine species from complex systems; (2) limited adsorption capacity for iodine vapor, especially under high humidity or low partial pressure conditions, and iodine is easy to desorb after adsorption; (3) the material is non-degradable, difficult to regenerate after adsorption saturation, and the cycle performance decays quickly, eventually forming stable solid waste, which poses environmental disposal risks and potential radioactive waste increment problems.

[0006] In recent years, some studies have attempted to use functionalized macrocyclic molecules (such as calixarene derivatives) to improve adsorption selectivity. However, their synthesis routes are complex and costly, and they mostly exist in powder or small molecule form, making them difficult to apply directly to dynamic gas phase adsorption or large-scale water treatment processes. They are also limited in terms of stability, ease of recovery, and engineering applicability.

[0007] Therefore, developing a novel adsorbent material with a simple synthetic route, controllable cost, specific and efficient ability to capture iodine vapor and iodine tri-ions, and good recyclability and ultimate degradability is of great significance for achieving efficient treatment and resource recovery of iodine pollutants and avoiding secondary pollution. This is both an urgent need in the field of environmental engineering and a key link in the strategy of minimizing radioactive waste. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention provides a degradable cross-linked polymer material for efficient iodine capture, its preparation method, and its application.

[0009] The technical solution adopted in this invention is as follows:

[0010] A biodegradable crosslinked polymer material for efficient iodine capture, wherein the polymer material is a three-dimensional network polymer obtained by condensation reaction of polyaldehyde-functionalized monomers and polyfunctional thiols; wherein the polyaldehyde-functionalized monomers are directly obtained by one-pot nucleophilic substitution reaction of lignin-derived aldehyde-containing phenolic biomass raw materials and cyanuric chloride (2,4,6-trichloro-1,3,5-triazine), and the monomer structure does not contain heterocalix aromatic macrocycles.

[0011] Furthermore, the lignin-derived aldehyde-containing phenolic biomass raw material is at least one of 4-hydroxybenzaldehyde, vanillin, or eugenol, and its amount is 3 to 4 times that of cyanuric chloride.

[0012] Furthermore, the polyfunctional thiol is selected from one of 1,4-butanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol, 1,7-heptanedithiol, 1,8-octanedithiol, 1,4-benzenedimethylthiol, bis(2-mercaptoethyl) ether, 3,6-dioxo-1,8-octanedithiol, diethylene glycol di(ethanethiol), hexa(3-mercaptopropionic acid) dipentaerythritol ester, and trimethylolpropane tri(3-mercaptopropionate).

[0013] Furthermore, the equilibrium adsorption capacity of the polymer material for iodine vapor is not less than 300% of its own mass, preferably 300%-400%.

[0014] The preparation method of the above-mentioned biodegradable crosslinked polymer material includes the following steps:

[0015] S1. In an alkaline catalyst and a first organic solvent, lignin-derived aldehyde-containing phenolic biomass raw materials are reacted with cyanuric chloride at 60℃-70℃, and after post-treatment, polyaldehyde-functionalized monomers are obtained.

[0016] S2. In an acidic catalyst and a second organic solvent, the polyaldehyde-functionalized monomer obtained in step S1 is subjected to a condensation reaction with a polyfunctional thiol at 20℃-80℃, and a biodegradable crosslinked polymer material is obtained after post-treatment.

[0017] Further, in step S1, the alkaline catalyst is triethylamine, potassium carbonate or sodium hydroxide, and the first organic solvent is DMSO, DMF, tetrahydrofuran, 1,4-dioxane, acetone or acetonitrile, and its amount is 30-50 times the mass of cyanuric chloride.

[0018] Further, in step S2, the second organic solvent is dichloromethane, chloroform, or 1,2-dichloroethane, and its amount is 5-10 times the mass of cyanuric chloride. The molar ratio of the polyaldehyde functionalized monomer to the polyfunctional thiol is 1:1-4, preferably 1:2-3. The acidic catalyst is trifluoroacetic acid, and its amount is 0.5%-5% of the total mass of the reaction raw materials, preferably 1%-3%. The reaction temperature is 20℃-80℃, preferably 30℃-60℃, and the reaction time is 0.5-3 hours, preferably 1-2 hours.

[0019] The above-mentioned degradable cross-linked polymer materials are used in the adsorption or capture of gaseous or liquid iodine pollutants.

[0020] Further, specific applications include: exposing the polymer material to a gaseous environment containing iodine vapor, or immersing it in an aqueous solution of iodine tri-antinal ions with a concentration of 50 ppm-100 ppm, using a polymer material concentration of 20-50 mg / L, and an adsorption time of 30-60 min.

[0021] The degradation and recycling method of the above-mentioned degradable cross-linked polymer material is as follows: the polymer material that is saturated with adsorption or is waste is placed in an alcohol solution containing potassium carbonate and heated at 50℃-80℃ to achieve polymer degradation.

[0022] Furthermore, in the potassium carbonate-containing alcohol solution, the alcohol is ethanol or methanol.

[0023] The beneficial effects of this invention are as follows:

[0024] (1) Based on the active sites such as nitrogen, oxygen and sulfur in its polymer network, the material of the present invention exhibits a specific high affinity for iodine vapor and iodine tri-antion. It can achieve a removal rate of more than 90% in low concentration (50 ppm) aqueous phase adsorption, and the adsorption capacity for iodine vapor can be more than 3 times the mass of the material itself, thus solving the problem of poor selectivity and limited adsorption capacity of traditional adsorbents for iodine pollutants.

[0025] (2) The material of this invention forms a stable three-dimensional network structure through cross-linking. After adsorption saturation, it can be efficiently desorbed and recycled by simple acid washing, which significantly reduces operating costs. In particular, the material can be completely degraded under mild potassium carbonate alcohol solution conditions after disposal, which fundamentally avoids the risk of secondary pollution and radioactive accumulation of solid waste caused by traditional adsorption materials.

[0026] (3) This invention uses renewable lignin derivatives as core raw materials, has a simple synthesis route, eliminates the preparation steps of complex macrocyclic structures, has mild conditions and economical cost, and has both high-efficiency adsorption and degradability characteristics, which is in line with the concept of green chemistry and sustainable development, and lays a solid foundation for large-scale preparation and practical application. Attached Figure Description

[0027] Figure 1 This is a diagram showing the material synthesis steps and structure in Example 1.

[0028] Figure 2 The infrared spectrum of the polymer material prepared in Example 1 is shown. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to specific embodiments, but the present invention is not limited thereto.

[0030] Example 1

[0031] The material synthesis steps and structural diagram in Example 1 are as follows: Figure 1 As shown, the specific steps include the following:

[0032] 1 mol of cyanuric chloride and 4 mol of vanillin were dissolved in 50 mol of tetrahydrofuran, and then 4 mol of triethylamine were added. The mixture was reacted at 66 °C for 24 h. After the reaction, the solid was filtered, washed three times with hot water, and dried to obtain the polyaldehyde-functionalized monomer. For polymerization, 1 mol of the polyaldehyde-functionalized monomer and 3 mol of 1,4-butanedithiol were added to a glass-sealed tube, and then 10 mol of 1,2-dichloroethane was added as a solvent to sonicate the reactants. After dissolution, 0.01 mol of trifluoroacetic acid was added, the tube was sealed, and the mixture was reacted in an oil bath at 60 °C for 1 h. After the reaction, the solvent was removed by vacuum distillation, and the mixture was repeatedly washed with methanol and then vacuum dried to obtain the biodegradable crosslinked polymer material based on biomass. In use, 20 mg of this material was added to a prepared 1 L 50 ppm iodine tri-anion solution. After stirring and adsorption for 30 min, the concentration of elemental iodine in the solution was measured to be 4.8 ppm, and the removal rate of iodine tri-anion was 90.4%.

[0033] The infrared spectrum of the polymer material prepared in Example 1 is shown below. Figure 2 As shown. By Figure 2 It can be seen that in the polymer, the wavenumber corresponding to the aldehyde group in the monomer is 1700 cm⁻¹. -1 The absorption peak almost completely disappeared, indicating that the polymerization reaction had fully occurred.

[0034] Example 2

[0035] 1 mol of cyanuric chloride and 4 mol of vanillin were dissolved in 50 mol of tetrahydrofuran, and then 4 mol of triethylamine were added. The mixture was reacted at 66 °C for 24 h. After the reaction was completed, the solid was filtered, washed three times with hot water, and dried to obtain the polyaldehyde-functionalized monomer. For polymerization, 1 mol of the polyaldehyde-functionalized monomer and 3 mol of 1,4-butanedithiol were added to a glass-sealed tube, and then 10 mol of 1,2-dichloroethane was added as a solvent to sonicate the reactants. After dissolution, 0.01 mol of trifluoroacetic acid was added, the tube was sealed, and the mixture was reacted in an oil bath at 60 °C for 1 h. After the reaction was completed, the solvent was removed by vacuum distillation, and the mixture was repeatedly washed with methanol and then vacuum dried to obtain the biodegradable crosslinked polymer material based on biomass.

[0036] When using the material, place 20mg of the material in a container filled with iodine vapor. After 24 hours, the material will adsorb 220% of its own weight of iodine vapor. After 48 hours, the material will adsorb 320% of its own weight of iodine vapor.

[0037] Example 3

[0038] 1 mol of cyanuric chloride and 4 mol of eugenol were dissolved in 50 mol of tetrahydrofuran, followed by the addition of 4 mol of triethylamine. The reaction was carried out at 66 °C for 24 h. After the reaction was completed, the solid was filtered, washed three times with hot water, and dried to obtain the polyaldehyde-functionalized monomer. For polymerization, 1 mol of the polyaldehyde-functionalized monomer and 3 mol of 1,4-phenylenediol were added to a glass-sealed tube, followed by the addition of 10 mol of 1,2-dichloroethane as a solvent for ultrasonic dissolution. After dissolution, 0.01 mol of trifluoroacetic acid was added, and the tube was sealed. The reaction was then carried out in an oil bath at 60 °C for 1 h. After the reaction was completed, the solvent was removed by vacuum distillation, and the mixture was repeatedly washed with methanol and then dried under vacuum to obtain the target polymer material.

[0039] When using the material, place 20 mg of the material in a sealed container filled with iodine vapor. After 24 hours, weigh the material. The mass of iodine vapor adsorbed by the material reaches 200% of its own mass. After 48 hours, the adsorption amount reaches 300% of its own mass.

[0040] Example 4

[0041] 1 mol of cyanuric chloride and 3.5 mol of 4-hydroxybenzaldehyde were dissolved in 45 mol of DMF, followed by the addition of 3.5 mol of potassium carbonate. The reaction was carried out at 65 °C for 24 h. After the reaction, the mixture was filtered, washed with hot water, and dried to obtain a polyaldehyde-functionalized monomer. For polymerization, 1 mol of this monomer and 2.5 mol of bis(2-mercaptoethyl) ether were added to a reaction flask, dissolved in 8 mol of dichloromethane, and then 0.015 mol of trifluoroacetic acid were added. The mixture was stirred at 40 °C for 2 h. After the reaction, the solvent was removed, the mixture was washed with methanol, and dried under vacuum to obtain the polymer material.

[0042] 20 mg of the material was added to 1 L of 80 ppm iodine tri-antion aqueous solution. After stirring and adsorption for 40 min, the residual iodine concentration was measured to be 7.2 ppm, with a removal rate of 91.0%. The adsorbed material was washed with 5% hydrochloric acid solution for 30 min, filtered, washed with water, and dried. It was then added again to a fresh iodine tri-antion solution of the same concentration for secondary adsorption. The removal rate remained at 89.5%, indicating that the material has good regeneration and recycling performance.

[0043] Example 5

[0044] 1 mol of cyanuric chloride and 4 mol of vanillin were dissolved in 50 mol of tetrahydrofuran, and 4 mol of sodium hydroxide were added. The mixture was reacted at 70 °C for 20 h, followed by post-treatment with polyaldehyde-functionalized monomers. During polymerization, 1 mol of this monomer and 1.2 mol of trimethylolpropane tris(3-mercaptopropionate) (functionality = 3) were added to a glass-sealed tube, dissolved in 10 mol of chloroform, and 0.02 mol of trifluoroacetic acid were added. The mixture was reacted at 50 °C for 1.5 h. Post-treatment yielded a crosslinked polymer material.

[0045] The material achieved an adsorption removal rate of 93.2% for iodine trioxide ions (60 ppm). 100 mg of the saturated material was placed in 20 mL of a 0.5 mol / L potassium carbonate ethanol solution and heated and stirred at 70 °C for 6 h. The material gradually dissolved, and the solution turned dark brown. After filtration and washing of the insoluble matter, the degradation rate was greater than 95%, indicating that the material can be essentially completely degraded under mild alkaline conditions.

[0046] Comparative Example 1

[0047] Take 20 mg of commercial granular activated carbon (particle size 200 mesh, specific surface area 1000 m²). 2 (g), added to 1 L of 50ppm iodine tri-antion aqueous solution, stirred and adsorbed for 30 min, the remaining iodine concentration was measured to be 19.5 ppm, and the removal rate was 61.0%. Under the same conditions, the removal rate of the material in Example 1 of the present invention was 90.4%, which is significantly better than that of traditional physical adsorbents.

[0048] Comparative Example 2

[0049] 1 mol of cyanuric chloride was directly polymerized with 1,4-butanedithiol under the conditions of Example 1 to obtain a comparative polymer material. In the same iodine vapor adsorption test (48 h), this material adsorbed only 45% of its own mass, far lower than the material of this invention (≥300%), demonstrating that the lignin-derived aldehyde groups are crucial for constructing highly iodine-affinity active sites.

Claims

1. A biodegradable cross-linked polymer material for efficient iodine capture, characterized in that, The polymer material is a three-dimensional network polymer obtained by condensation reaction of polyaldehyde-functionalized monomers and polyfunctional thiols; wherein, the polyaldehyde-functionalized monomers are directly obtained by one-pot nucleophilic substitution reaction of lignin-derived aldehyde-containing phenolic biomass raw materials and cyanuric chloride, and the monomer structure does not contain heterocalix aromatic macrocycles.

2. The biodegradable crosslinked polymer material as described in claim 1, characterized in that, The lignin-derived aldehyde-containing phenolic biomass raw material is at least one of 4-hydroxybenzaldehyde, vanillin, or eugenol, and its amount is 3 to 4 times that of cyanuric chloride.

3. The biodegradable crosslinked polymer material as described in claim 1, characterized in that, The polyfunctional thiols are selected from one of the following: 1,4-butanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol, 1,7-heptanedithiol, 1,8-octanedithiol, 1,4-benzenedimethylthiol, bis(2-mercaptoethyl) ether, 3,6-dioxo-1,8-octanedithiol, diethylene glycol di(ethanethiol), hexa(3-mercaptopropionic acid) dipentaerythritol ester, and trimethylolpropane tri(3-mercaptopropionate).

4. The biodegradable crosslinked polymer material according to claim 1, characterized in that, The equilibrium adsorption capacity of the polymer material for iodine vapor is not less than 300% of its own mass.

5. The method for preparing the biodegradable crosslinkable polymer material according to any one of claims 1 to 4, characterized in that, Includes the following steps: S1. In an alkaline catalyst and a first organic solvent, lignin-derived aldehyde-containing phenolic biomass raw materials are reacted with cyanuric chloride at 60℃-70℃, and after post-treatment, polyaldehyde-functionalized monomers are obtained. S2. In an acidic catalyst and a second organic solvent, the polyaldehyde-functionalized monomer obtained in step S1 is subjected to a condensation reaction with a polyfunctional thiol at 20℃-80℃, and a biodegradable crosslinked polymer material is obtained after post-treatment.

6. The preparation method according to claim 5, characterized in that, In step S1, the alkaline catalyst is triethylamine, potassium carbonate, or sodium hydroxide; the first organic solvent is DMSO, DMF, tetrahydrofuran, 1,4-dioxane, acetone, or acetonitrile, and its amount is 30-50 times the mass of cyanuric chloride.

7. The preparation method according to claim 5, characterized in that, In step S2, the acidic catalyst is trifluoroacetic acid, and its amount is 0.5% to 5% of the total mass of the reaction raw materials; the second organic solvent is dichloromethane, chloroform or 1,2-dichloroethane, and its amount is 5 to 10 times the mass of cyanuric chloride; the molar ratio of polyaldehyde functionalized monomer to polyfunctional thiol is 1:1 to 4, the reaction temperature is 20 to 80°C, and the reaction time is 0.5 to 3 hours.

8. The use of the biodegradable crosslinked polymer material according to any one of claims 1 to 4 in the adsorption or capture of gaseous or liquid iodine pollutants.

9. The application according to claim 8, characterized in that, The specific application involves exposing the polymer material to a gaseous environment containing iodine vapor, or immersing it in an aqueous solution of iodine tri-antinal ions with a concentration of 50 ppm-100 ppm, wherein the amount of polymer material used is 20 mg / L-50 mg / L, and the adsorption time is 30 min-60 min.

10. A method for degrading and recycling a biodegradable crosslinkable polymer material as described in any one of claims 1 to 4, characterized in that, The polymer material that has been saturated with adsorption or is now discarded is placed in an alcohol solution containing potassium carbonate and heated at 50°C-80°C to degrade the polymer.

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