A porouso organic polymer of amidoxime and a preparation method and application thereof

Abstract

The application relates to a kind of amidoxime porous organic polymer and its preparation method and application, and relates to heavy metal adsorption technical field, solve the problem that the specific adsorption selectivity of heavy metal adsorption material in prior art to heavy metal is insufficient, adsorption capacity is small, it is difficult to realize the efficient enrichment and rapid removal of heavy metal ions, and the problem that the development of specific adsorption group in prior art is in technical blank.The present application is by adding sodium nitrite aqueous solution to diphenylamine solution to carry out diazotization reaction, then adding ethyl acetate solution containing 4-hydroxyphenyl acetonitrile and triethylamine to carry out diazo coupling interfacial polymerization reaction, to obtain cyanogen-rich porous organic polymer material;The obtained material is immersed in methanol solution containing hydroxylamine hydrochloride and trimethylamine to carry out post-amidoxime modification, to obtain heavy metal adsorption material.The present application effectively improves the adsorption efficiency and specific recognition adsorption capacity of heavy metal adsorption material, and can be applied to the field of water heavy metal pollution treatment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heavy metal adsorption, in particular to a kind of amidoxime porous organic polymer and its preparation method and application. BACKGROUND

[0002] At present, due to the production process of human industry, residual heavy metals such as lead, mercury and cadmium enter the natural environment and are enriched in aquatic organisms, resulting in serious heavy metal pollution in water bodies. Due to the persistence, bioaccumulation and high toxicity of residual heavy metals, they not only pose a serious threat to ecological safety, but also have a profound impact on public health and human health. Therefore, it is of great practical value and practical significance to develop adsorbent materials that can efficiently remove heavy metals from water bodies.

[0003] The current water heavy metal adsorbent materials face problems such as lack of rich pore structure and small pore size. For example, Chinese invention patent CN119236904A discloses a lead-antimony heavy metal adsorbent prepared using sodium alginate as raw material. The adsorbent has good selective adsorption for trivalent antimony ions, but due to the lack of ordered and high specific surface area pore system in its structure, the effective adsorption sites are limited, which restricts the further improvement of adsorption capacity. For example, Chinese invention patent CN118022705A discloses a composite polymer adsorbent. The adsorbent is biodegradable and environmentally friendly, but the internal structure of the adsorbent is relatively dense, lacking sufficient hierarchical pores and high specific surface area, which limits the number and distribution of adsorption sites, resulting in limited overall adsorption capacity and difficulty in achieving efficient enrichment and rapid removal of heavy metal ions. For example, sulfur-containing metal-organic framework materials (MOFs) have an adsorption capacity for mercury of more than 1000 mg / g, which is 5-10 times higher than that of traditional activated carbon. However, such materials usually have small pore sizes, which is not conducive to the mass transfer rate inside the material.

[0004] To improve the above problems, some researchers have applied porous organic materials (POPs) in heavy metal adsorption due to their adjustable pore structure and surface chemical properties. POPs have become a reliable choice for efficient adsorbent materials due to their rich and suitable pore structure. At the same time, their cross-linked network structure also gives the material good cycle stability, meeting the long-term stable circulation of adsorption-regeneration. However, the current POPs materials still lack the development of specific adsorption groups and the combination of process treatment methods, resulting in insufficient specificity of adsorption selectivity for heavy metals in water bodies, difficulty in achieving efficient adsorption process, and easy occurrence of invalid adsorption of non-target ions in multi-component systems, which not only reduces the effective adsorption capacity of the material, but also may disrupt the steady-state distribution of ions in the original system, affecting the actual application effect.

[0005] Therefore, it is of great significance to develop a heavy metal adsorbent with adjustable pore structure, surface chemical properties and specific adsorption sites, to improve the adsorption capacity and selectivity of the adsorbent, and to realize efficient identification and separation of target ions in complex water or multi-component system, so as to promote the research and development of high-performance environmental purification materials and the sustainable development of heavy metal pollution treatment technology. SUMMARY

[0006] In order to solve the problems of insufficient specific adsorption selectivity of heavy metal adsorption materials in the prior art, small adsorption capacity, and difficulty in realizing efficient enrichment and rapid removal of heavy metal ions, and the problem that the development of specific adsorption groups in the prior art is in a technical blank, the present application proposes a kind of amidoxime porous organic polymer and its preparation method and application. The technical scheme of the present application is as follows:

[0007] A preparation method of a kind of amidoxime porous organic polymer, comprising the following preparation steps:

[0008] S1: adding sodium nitrite aqueous solution to the o-tolidine solution to carry out diazotization reaction, and then adding ethyl acetate solution containing 4-hydroxyphenyl acetonitrile and triethylamine to stir to carry out diazo coupling interfacial polymerization reaction, separating the solid product, carrying out soxhlet extraction, drying to obtain a cyan-rich porous organic polymer material;

[0009] S2: immersing the cyan-rich porous organic polymer material in a methanol solution containing hydroxylamine hydrochloride and trimethylamine to carry out post-amidoxime modification, filtering, washing and drying after the reaction to obtain a mesoporous amidoxime porous organic polymer.

[0010] Further, the solvent in the o-tolidine solution in S1 is hydrochloric acid aqueous solution, the volume ratio of hydrochloric acid to water in the hydrochloric acid aqueous solution is 1:2, the temperature of the hydrochloric acid aqueous solution is 0~5℃, and the concentration of the o-tolidine solution is 2~15mmol / L.

[0011] Further, the concentration of the sodium nitrite aqueous solution in S1 is 0.03~0.1 g / mL; the molar ratio of o-tolidine to sodium nitrite is 1:2.2~2.5.

[0012] Further, the time of the diazotization reaction in S1 is 1 h, and the reaction temperature is 0~5℃; the time of the diazo coupling interfacial polymerization reaction is 2~24 h, and the reaction temperature is 0~5℃.

[0013] Further, the molar ratio of o-tolidine to 4-hydroxyphenyl acetonitrile in S1 is 1:0.5~2, the concentration of 4-hydroxyphenyl acetonitrile in the ethyl acetate solution containing 4-hydroxyphenyl acetonitrile and triethylamine is 2~20 mmol / L; and the molar ratio of 4-hydroxyphenyl acetonitrile to triethylamine is 1:2.

[0014] Further, the time of the Soxhlet extraction in S1 is 24 h, and the extraction solvent of the Soxhlet extraction is methanol.

[0015] Further, the time of the post-amidoxime modification reaction in S2 is 12-72 h, and the temperature of the post-amidoxime modification reaction is 70 DEG C.

[0016] Further, the mass ratio of the cyano-rich porous organic polymer material to hydroxylamine hydrochloride and trimethylamine in S2 is 1:5:7.5; the concentration of hydroxylamine hydrochloride in the methanol solution containing hydroxylamine hydrochloride and trimethylamine is 1.44 mol / L, and the concentration of trimethylamine is 2.54 mol / L; the washing is sequentially washing with methanol and deionized water.

[0017] An amidoxime porous organic polymer is prepared by the preparation method.

[0018] The application of the amidoxime porous organic polymer is applied to the field of water heavy metal pollution treatment.

[0019] Compared with the prior art, the present application solves the problems of insufficient specific adsorption selectivity of the heavy metal adsorption material, small adsorption capacity, and difficulty in realizing efficient enrichment and rapid removal of heavy metal ions in the prior art, and the development of specific adsorption groups in the prior art is in a technical blank, and specific beneficial effects are as follows:

[0020] 1. Effectively improve the heavy metal adsorption capacity: the present application utilizes diazotization coupling interface polymerization reaction and post-amidoxime modification of benzidine and 4-hydroxyphenyl acetonitrile at the micro-phase water-oil interface to obtain an amidoxime porous organic polymer heavy metal adsorption material. The cross-linked rigid framework obtained by cross-linking of benzidine and 4-hydroxyphenyl acetonitrile has abundant mesoporous structures, which realizes efficient mass transfer process of the amidoxime porous organic polymer heavy metal adsorption material, and effectively improves the adsorption efficiency of the heavy metal adsorption material. The removal rate of mercury ions is more than 83%, the removal rates of copper ions, lead ions and nickel ions are more than 90%, and efficient enrichment and rapid removal of different heavy metal ions are realized.

[0021] 2. Effectively improve the specific recognition adsorption of heavy metal ions: since the amidoxime group can realize efficient and specific recognition adsorption of heavy metal ions, the specific adsorption capacity of the amidoxime porous organic polymer heavy metal adsorption material provided by the present application is effectively improved, the adsorption of excessive light metal ions with low harmfulness is avoided, and the unit adsorption capacity of heavy metal ions is improved.

[0022] 3. effectively improve the stability of heavy metal adsorption material: the invention carries out diazo coupling interfacial polymerization reaction at the micro-phase water-oil interface, introduces amidoxy groups by hydroxylamine modification, constructs organic framework material with high cross-linked structure, realizes stable coexistence of hydrophobic main chain and hydrophilic functional groups, and endows amidoxy porous organic polymer heavy metal adsorption material with excellent chemical stability. Even for the heavy metal desorption (adsorption material regeneration) process which needs a large amount of acid treatment, the heavy metal adsorption material provided by the invention has excellent acid resistance and stability, can maintain the stability of structure and adsorption capacity in multiple adsorption-desorption cycles, and has good reusability and industrial application potential. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 Nitrogen adsorption-desorption curve of heavy metal adsorption material A;

[0024] Figure 2 Picture of adsorption column filled with heavy metal adsorption material A. DETAILED DESCRIPTION

[0025] In order to make the technical scheme of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely in combination with the drawings of the specification of the present application. It should be noted that the following embodiments are only used to better understand the technical scheme of the present application, and should not be understood as a limitation of the present application.

[0026] Example 1.

[0027] S1: Dissolve 1.84 g of benzidine (10 mmol) in 900 mL of 5℃ hydrochloric acid aqueous solution (volume ratio of hydrochloric acid to water is 1:2), after the benzidine is completely dissolved, add sodium nitrite aqueous solution (1.518 g of sodium nitrite (22 mmol), 30 mL of deionized water) dropwise to carry out diazotization reaction, the reaction time is 1 h to ensure sufficient reaction, and the solution temperature is maintained at 5℃. Then add 1 L of 4-hydroxyphenyl acetonitrile (1.33 g, 10 mmol) and triethylamine (20 mmol) in ethyl acetate solution to stir, carry out diazo coupling interfacial polymerization reaction at the micro-phase water-oil interface for 12 h, the reaction temperature is 5℃, after the reaction is completed, the solid product is separated from the system, and Soxhlet extraction is carried out with methanol for 24 h, and then dried to obtain a cyano-rich porous organic polymer material A.

[0028] S2: 1 g of the cyan group-rich porous organic polymer material A was immersed in a 50 mL methanol solution containing 5 g of hydroxylamine hydrochloride and 7.5 g of trimethylamine, and reacted at 70°C for 48 h to perform the post-aminooxime modification of the porous organic polymer material; after the reaction was completed, the solid product was filtered, washed with methanol and deionized water in sequence, and dried to obtain the mesoporous aminooxime-rich porous organic polymer heavy metal adsorption material A. As Figure 1 The nitrogen adsorption-desorption curve of the aminooxime-rich porous organic polymer heavy metal adsorption material A was obtained, and it can be seen from the figure that the nitrogen adsorption-desorption isotherm of the aminooxime-rich porous organic polymer heavy metal adsorption material A presents a typical type IV curve with obvious H3 hysteresis loop, indicating that it has abundant mesoporous structure and certain microporous characteristics. The rapid adsorption in the low relative pressure region reflects the existence of micropores, while the slow rise and obvious hysteresis loop in the medium-high pressure region show that there are a large number of open mesopores in the form of sheet stacking or crack in the material. Such hierarchical pore structure not only endows the material with higher specific surface area and sufficient adsorption sites, but also effectively improves the mass transfer rate and diffusion efficiency of target ions, which is helpful for the rapid enrichment and high capacity adsorption of heavy metal ions.

[0029] Example 2.

[0030] S1: 1.84 g of benzidine (10 mmol) was dissolved in 720 mL of 5°C hydrochloric acid aqueous solution (volume ratio of hydrochloric acid to water was 1:2), and then sodium nitrite aqueous solution (1.725 g of sodium nitrite (25 mmol), 17.25 mL of deionized water) was added dropwise to perform diazotization reaction, the reaction time was 1 h to ensure sufficient reaction, and the solution temperature was maintained at 5°C. Then 0.25 L of 4-hydroxyphenylacetonitrile (0.67 g, 5 mmol) and triethylamine (10 mmol) ethyl acetate solution were added and stirred to perform diazo coupling interfacial polymerization at the micro-phase water-oil interface for 24 h, the reaction temperature was 5°C, after the reaction was completed, the solid product was separated from the system, and Soxhlet extraction was performed with methanol for 24 h, and then dried to obtain the cyan group-rich porous organic polymer material B.

[0031] S2: 1 g of the cyan group-rich porous organic polymer material B was immersed in a 50 mL methanol solution containing 5 g of hydroxylamine hydrochloride and 7.5 g of trimethylamine, and reacted at 70°C for 12 h to perform the post-aminooxime modification of the porous organic polymer material; after the reaction was completed, the solid product was filtered, washed with methanol and deionized water in sequence, and dried to obtain the mesoporous aminooxime-rich porous organic polymer heavy metal adsorption material B.

[0032] Example 3.

[0033] S1: 1.84 g of benzidine (10 mmol) was dissolved in 5℃, 2400 mL of an aqueous hydrochloric acid solution (volume ratio of hydrochloric acid to water was 1:2), after the benzidine was completely dissolved, an aqueous sodium nitrite solution (1.587 g of sodium nitrite (22 mmol), 20 mL of deionized water) was added dropwise to carry out the diazotization reaction, the reaction time was 1 h to ensure sufficient reaction, and the solution temperature was maintained at 5℃. Then 3 L of 4-hydroxyphenyl acetonitrile (2.00 g, 15 mmol) and triethylamine (30 mmol) in ethyl acetate solution were added to stir, and the diazo coupling interfacial polymerization reaction at the microphase water-oil interface was carried out for 24 h, the reaction temperature was 5℃, after the reaction was completed, the solid product was separated from the system, and Soxhlet extraction was carried out with methanol for 24 h, and then dried to obtain a cyan-rich porous organic polymer material C.

[0034] S2: 1 g of the cyan-rich porous organic polymer material B was immersed in a 50 mL methanol solution containing 5 g of hydroxylamine hydrochloride and 7.5 g of trimethylamine, and reacted at 70℃ for 4 h to modify the porous organic polymer material by post-amidoxime modification; after the reaction was completed, the solid product was filtered, washed with methanol and deionized water in turn, and dried to obtain a mesoporous amidoxime-rich porous organic polymer heavy metal adsorption material C.

[0035] Example 4.

[0036] S1: 1.84 g of benzidine (10 mmol) was dissolved in 5℃, 2400 mL of an aqueous hydrochloric acid solution (volume ratio of hydrochloric acid to water was 1:2), after the benzidine was completely dissolved, an aqueous sodium nitrite solution (1.587 g of sodium nitrite (22 mmol), 20 mL of deionized water) was added dropwise to carry out the diazotization reaction, the reaction time was 1 h to ensure sufficient reaction, and the solution temperature was maintained at 5℃. Then 3 L of 4-hydroxyphenyl acetonitrile (2.00 g, 15 mmol) and triethylamine (30 mmol) in ethyl acetate solution were added to stir, and the diazo coupling interfacial polymerization reaction at the microphase water-oil interface was carried out for 24 h, the reaction temperature was 5℃, after the reaction was completed, the solid product was separated from the system, and Soxhlet extraction was carried out with methanol for 24 h, and then dried to obtain a cyan-rich porous organic polymer material C.

[0037] S2: 1 g of the cyan-rich porous organic polymer material B was immersed in a 50 mL methanol solution containing 5 g of hydroxylamine hydrochloride and 7.5 g of trimethylamine, and reacted at 70℃ for 4 h to modify the porous organic polymer material by post-amidoxime modification; after the reaction was completed, the solid product was filtered, washed with methanol and deionized water in turn, and dried to obtain a mesoporous amidoxime-rich porous organic polymer heavy metal adsorption material C.

[0038] Comparative Example 1.

[0039] Commercial activated carbon powder with a particle size of 200 mesh was selected as a comparative adsorption material.

[0040] 2 g of each of the mesoporous-rich amidoxime-functionalized porous organic polymers heavy metal adsorption materials A to D prepared in Examples 1 to 4 were respectively taken and loaded into an adsorption column as shown in Figure 2 The adsorption experiment of heavy metal ions was carried out by a flow circulation method. The liquid flow rate was set to 20 mL / min, the concentration of the heavy metal simulation water sample was 100 ppm, and the volume of the water sample used was 100 mL. The heavy metal salts used to configure the heavy metal simulation water sample were mercury nitrate, copper nitrate, lead nitrate and nickel nitrate. The ion concentration of the water sample before and after adsorption was analyzed by an inductively coupled plasma spectrometer, and the removal rate of heavy metal ions was calculated. The following table is the adsorption performance results of the mesoporous-rich amidoxime-functionalized porous organic polymers heavy metal adsorption materials A to D and the commercial activated carbon powder in the comparative example. As can be seen from the table, the mesoporous-rich amidoxime-functionalized porous organic polymers heavy metal adsorption materials A to D prepared in Examples 1 to 4 have excellent metal removal capacity, in which the removal rate of mercury ions is all above 83%, the removal rates of copper ions, lead ions and nickel ions are all above 90%, which is much higher than the metal removal rate of the commercial activated carbon powder adsorption material.

[0041] This is due to the heavy metal adsorption material of the amidoxime-converted porous organic polymer is obtained by diazo coupling interfacial polymerization of benzidine and 4-hydroxyphenyl acetonitrile at the water-oil interface and subsequent amidoxime modification, the interfacial polymerization reaction is limited at the water-oil interface, resulting in the arrangement of the polymer chain segment not being tight, and the rigid structure of benzidine and the polar functional group of 4-hydroxyphenyl acetonitrile jointly act to promote microphase separation and pore generation; meanwhile, the nitrile group is converted into the amidoxime group with a larger volume in the amidoxime process, further causing the skeleton to expand and the chain segment to relax, enhancing the development and expansion of the pore, so that a large number of mesoporous structures are formed, and then a high-efficiency mass transfer process is realized, and the adsorption efficiency of the adsorption material is improved. Secondly, the abundant amidoxime groups have more excellent heavy metal specific adsorption capacity than hydroxyl groups, amine groups and sulfonic acid groups, reducing the adsorption of low-toxicity light metal ions and improving the unit adsorption capacity of the adsorption material. Thirdly, the highly cross-linked framework material obtained by the diazo coupling interfacial polymerization reaction at the microphase water-oil interface has high chemical stability, and compared with the organic framework material (COFs) and metal-organic framework material (MOFs) obtained by Schiff base reaction or organic-inorganic coordination, has more excellent structural stability, especially for the heavy metal desorption (adsorption material regeneration) process which needs a large amount of acid treatment, the amidoxime-converted porous organic polymer heavy metal adsorption material involved in the present application has excellent acid resistance and stability, and can realize the adsorption-desorption circulation process of such adsorption material. In addition, the abundant amidoxime groups in the amidoxime-converted porous organic polymer heavy metal adsorption material can realize efficient and specific recognition and adsorption of heavy metal ions, avoid the adsorption of excessive light metal ions with low harm, and improve the unit adsorption capacity of heavy metal ions.

[0042]

[0043] In summary, the heavy metal adsorption material is obtained by using benzidine and 4-hydroxyphenyl acetonitrile to perform diazo coupling interfacial polymerization at the microphase water-oil interface and subsequent amidoxime modification, a large number of mesoporous structures are formed, a high-efficiency mass transfer process of the heavy metal adsorption material is realized, the adsorption efficiency of the heavy metal adsorption material is effectively improved, and efficient enrichment and rapid removal of different heavy metal ions are realized. Meanwhile, the amidoxime group introduced in the present application effectively improves the specific recognition and adsorption capacity of heavy metal ions and the acid resistance, and has good reusability and industrial application potential.

[0044] The above examples are only used to help understand the method of the present application and its core idea. It should be noted that those skilled in the art can make some improvements and modifications to the present application without departing from the principles of the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

[0045] The foregoing description of the embodiments disclosed will so fully reveal the general nature of the application that others can, by applying current knowledge of the art, adapt it for other purposes or modify it to suits the particular specifications or testing environment to which it is applied, without undue experimentation necessary. Therefore, the application is not to be limited to the specific embodiments disclosed herein but includes all such embodiments falling within the scope of the following claims.

Claims

1. A method for preparing a porou s organic polymer of amidoxime, characterized by, The preparation method comprises the following steps: S1: adding an aqueous sodium nitrite solution to a benzidine solution to perform a diazotization reaction, and then adding an ethyl acetate solution containing 4-hydroxyphenyl acetonitrile and triethylamine to perform a diazonium coupling interfacial polymerization reaction, separating a solid product, performing Soxhlet extraction, drying, and obtaining a cyan-rich porous organic polymer material; S2: immersing the cyan-rich porous organic polymer material in a methanol solution containing hydroxylamine hydrochloride and trimethylamine to perform a post-aimed modification, filtering, washing, and drying after the reaction to obtain a mesoporous amine-oxime porous organic polymer.

2. The method for preparing a porou s organic polymer of an am i doxime according to claim 1, characterized by, The solvent in the benzidine solution in S1 is an aqueous hydrochloric acid solution, the volume ratio of hydrochloric acid to water in the aqueous hydrochloric acid solution is 1:2, the temperature of the aqueous hydrochloric acid solution is 0-5℃, and the concentration of the benzidine solution is 2-15 mmol / L.

3. The method for preparing a porou s organic polymer of an am i doxime according to claim 1, characterized by, The concentration of the aqueous sodium nitrite solution in S1 is 0.03-0.1 g / mL, and the molar ratio of benzidine to sodium nitrite is 1:2.2-2.

5.

4. The method for preparing a porou s organic polymer of an am i doxime according to claim 1, characterized by, The time of the diazotization reaction in S1 is 1 h, and the reaction temperature is 0-5℃; the time of the diazonium coupling interfacial polymerization reaction is 2-24 h, and the reaction temperature is 0-5℃.

5. The method of claim 1, wherein the preparation of the porou s organic polymer of the am i doxime is characterized in that, The molar ratio of benzidine to 4-hydroxyphenyl acetonitrile in S1 is 1:0.5-2, the concentration of 4-hydroxyphenyl acetonitrile in the ethyl acetate solution containing 4-hydroxyphenyl acetonitrile and triethylamine is 2-20 mmol / L, and the molar ratio of 4-hydroxyphenyl acetonitrile to triethylamine is 1:

2.

6. The method of claim 1, wherein the preparation of the porou s organic polymer of the am i doxime is characterized in that, The time of the Soxhlet extraction in S1 is 24 h, and the extraction solvent is methanol.

7. The method of claim 1, wherein the preparation of the porou s organic polymer of the am i doxime is characterized in that, The time of the post-aimed modification reaction in S2 is 12-72 h, and the temperature of the post-aimed modification reaction is 70℃.

8. The method of claim 1, wherein the preparation of the porou s organic polymer of the am i doxime is characterized in that, The mass ratio of the cyan-rich porous organic polymer material to hydroxylamine hydrochloride and trimethylamine in S2 is 1:5:7.5, the concentration of hydroxylamine hydrochloride in the methanol solution containing hydroxylamine hydrochloride and trimethylamine is 1.44 mol / L, the concentration of trimethylamine is 2.54 mol / L, and the washing is sequentially performed with methanol and deionized water.

9. A co-amidoxime porous organic polymer, characterized in that, The mesoporous amine-oxime porous organic polymer is prepared by the preparation method in any one of claims 1-8.

10. Use of a co-amidoxime porous organic polymer, characterized in that, The mesoporous amine-oxime porous organic polymer is applied to the field of heavy metal pollution treatment of water bodies.

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