Preparation method of crosslinked modified exfoliated zirconium phosphate-polyethyleneimine nanocomposite aerogel

Abstract

The present invention discloses a preparation method of a crosslinked modified exfoliated zirconium phosphate - polyethyleneimine nanocomposite aerogel, which includes the steps of: using mercaptoethylamine as a guest molecule to perform intercalation treatment on α - zirconium phosphate to obtain mercapto - intercalated zirconium phosphate; modifying epichlorohydrin on the surface and between the layers of the mercapto - intercalated zirconium phosphate through a substitution reaction between mercapto and chlorine atoms to obtain epoxy - intercalated zirconium phosphate; ultrasonically dispersing the epoxy - intercalated zirconium phosphate in an aqueous solution of polyethyleneimine to carry out crosslinking modification and exfoliation reaction, using the epoxy - intercalated zirconium phosphate as a crosslinking agent to crosslink and graft polyethyleneimine on the surface and between the layers of zirconium phosphate, and finally freeze - drying the reaction solution to obtain the crosslinked modified exfoliated zirconium phosphate - polyethyleneimine nanocomposite aerogel. The present invention solves the problems that polyethyleneimine is likely to remain in the solution and the interfacial compatibility between zirconium phosphate and the resin matrix is poor, and realizes the efficient adsorption of heavy metal ions.

Description

Technical Field

[0001] The present invention relates to the technical field of aerogels, and particularly to a preparation method of a cross-linked modified exfoliated zirconium phosphate-polyethyleneimine nanocomposite aerogel. Background Art

[0002] As an adsorbent material for heavy metal ions, polyethyleneimine is rich in various amino functional groups such as primary amines, secondary amines, and tertiary amines on its molecular chain. These functional groups can specifically adsorb heavy metal ions through mechanisms such as electrostatic interaction and coordination binding. However, when polyethyleneimine is used alone as an adsorbent material, due to its good water solubility, part of the polyethyleneimine will remain in the solution, making it difficult to effectively remove heavy metal ions from water.

[0003] Figure 1 The layered nanomaterial α-zirconium phosphate shown has a large specific surface area, excellent mechanical properties, good thermal stability, and high ion exchange capacity, and is often used as a functional additive to enhance the adsorption efficiency of resin-based composites for heavy metals. However, the high crystallinity and small interlayer spacing of α-zirconium phosphate make it difficult to achieve uniform dispersion in the resin matrix. To improve its compatibility with the resin matrix and thus promote its synergistic effect with the matrix, surface modification treatment of α-zirconium phosphate is required. However, the current modification technologies are mainly limited to surface and edge modification, while the interlayer is still in a stacked unmodified state, and the attachment efficiency of the modifier is not high, resulting in limited improvement in compatibility, and thus limited improvement in the adsorption performance of its composite materials. Summary of the Invention

[0004] Aiming at the above-mentioned defects of the prior art, the present invention provides a preparation method of a cross-linked modified exfoliated zirconium phosphate-polyethyleneimine nanocomposite aerogel, which can achieve efficient adsorption of heavy metal ions while solving the problems that polyethyleneimine is easy to remain in the solution and the interfacial compatibility between zirconium phosphate and the resin matrix is poor.

[0005] The technical solution of the present invention is as follows: A preparation method of a cross-linked modified exfoliated zirconium phosphate-polyethyleneimine nanocomposite aerogel, comprising the following steps:

[0006] (1) Using mercaptoethylamine as a guest molecule, intercalating α-zirconium phosphate to obtain mercapto-intercalated zirconium phosphate;

[0007] (2) Modifying epichlorohydrin on the surface and interlayer of the mercapto-intercalated zirconium phosphate through a substitution reaction between mercapto and chlorine atoms to obtain epoxy-intercalated zirconium phosphate;

[0008] (3) Ultrasonically disperse the epoxidized intercalated zirconium phosphate in an aqueous solution of polyethyleneimine for crosslinking modification and exfoliation reaction. Using the epoxidized intercalated zirconium phosphate as a crosslinking agent, polyethyleneimine is crosslinked and grafted on the surface and between the layers of zirconium phosphate. Finally, the reaction solution is freeze-dried to obtain crosslinked modified exfoliated zirconium phosphate-polyethyleneimine nanocomposite aerogel.

[0009] Further, in step (1), specifically, ultrasonically disperse α-zirconium phosphate in deionized water, then slowly dropwise add an aqueous solution of mercaptoethylamine for intercalation reaction, and perform suction filtration, washing, and drying.

[0010] Further, the mass ratio of the α-zirconium phosphate to mercaptoethylamine is 1:(0.6 - 0.8), and the concentration of the mercaptoethylamine aqueous solution is 10 - 16 mg / mL.

[0011] Further, in the intercalation reaction in step (1), under the action of ultrasonic waves at 40 - 60 kHz, react for 5 - 7 h.

[0012] Further, in step (2), specifically, ultrasonically disperse the mercapto-functionalized intercalated zirconium phosphate in ethanol, then add epichlorohydrin and an acid-binding agent, and perform a stirring reaction, followed by suction filtration, washing, and drying.

[0013] Further, the mass ratio of the mercapto-functionalized intercalated zirconium phosphate, epichlorohydrin, and the acid-binding agent is 1:(0.5 - 1):(1 - 2), and the acid-binding agent is one of triethylamine and pyridine.

[0014] Further, in the stirring reaction in step (2), reflux and react at 80 - 90 °C for 4 - 6 h.

[0015] Further, in step (3), the mass ratio of the epoxidized intercalated zirconium phosphate to polyethyleneimine is 1:(8 - 20).

[0016] Further, in the crosslinking modification and exfoliation reaction in step (3), stir and react at 50 - 80 °C for 6 - 8 h.

[0017] Further, in the freeze-drying in step (3), freeze-dry the reaction solution at -50 - -40 °C for 30 - 50 h.

[0018] In the present invention, mercaptoethylamine is used as a guest molecule to intercalate zirconium phosphate, which also provides the possibility for subsequent modification. Subsequently, through the substitution reaction between mercapto groups and chlorine atoms, epichlorohydrin is modified on the surface and interlayer of zirconium phosphate, which not only further expands the interlayer spacing but also provides active sites for subsequent cross-linking grafting reactions. Then, using epoxidized intercalated zirconium phosphate as a cross-linking agent, through the reaction between epoxy groups and amino groups of polyethyleneimine, cross-linking grafting on the surface and interlayer of zirconium phosphate is achieved. This process not only constructs a stable cross-linking network between zirconium phosphate and polyethyleneimine, but also the steric hindrance effect generated by the cross-linking grafting reaction promotes the effective exfoliation of the interlayer of zirconium phosphate, forming an exfoliated nano-composite material. Finally, with the aid of freeze-drying technology, a nano-composite aerogel with both structural stability and excellent adsorption performance is prepared.

[0019] The advantages of the present invention compared with the prior art are as follows:

[0020] (1) Through the steric hindrance effect brought about by interlayer grafting modification, the present invention performs an efficient exfoliation treatment on intercalated zirconium phosphate. The exfoliated structure not only endows the composite material with a larger specific surface area and better performance, but also realizes the comprehensive modification of the surface, edge and interlayer of zirconium phosphate, effectively improving the adhesion rate of the modifier, significantly enhancing its interfacial compatibility with the matrix, promoting its synergistic effect with the matrix, and thus comprehensively improving the comprehensive performance of the composite material.

[0021] (2) The nano-composite aerogel prepared in the present invention not only has a rich pore structure, but also combines the excellent structural characteristics of exfoliated zirconium phosphate and the abundant active amino groups of polyethyleneimine. Due to the excellent interfacial compatibility, the deep combination and synergistic effect of the two in adsorption performance are realized, greatly improving its adsorption performance for heavy metal ions.

[0022] (3) In the nano-composite aerogel of the present invention, polyethyleneimine is stably cross-linked into a water-insoluble network structure, effectively solving the problem of its residue in the solution. Description of the Drawings

[0023] Figure 1 It is the SEM image of the original α-zirconium phosphate.

[0024] Figure 2 It is the SEM image of the exfoliated zirconium phosphate with surface cross-linked grafted polyethyleneimine obtained in Example 1.

[0025] Figure 3 It is the SEM image of the cross-linked modified exfoliated zirconium phosphate-polyethyleneimine nano-composite aerogel obtained in Example 1. Detailed Embodiments

[0026] The present invention will be further described below in conjunction with embodiments, but it is not intended to limit the present invention.

[0027] Example 1

[0028] A preparation method of crosslinked modified exfoliated zirconium phosphate - polyethyleneimine nanocomposite aerogel includes the following steps:

[0029] (1) 1 g of α - zirconium phosphate (13772 - 29 - 7, Shanghai Aladdin Reagent Co., Ltd.) was ultrasonically dispersed in deionized water, and then 60 mL of an aqueous solution of mercaptoethylamine with a concentration of 10 mg / mL was slowly added dropwise. Under the action of 40 kHz ultrasonic waves, an intercalation reaction was carried out for 7 h, followed by suction filtration, washing, and drying to obtain mercapto - intercalated zirconium phosphate.

[0030] (2) 1 g of the obtained mercapto - intercalated zirconium phosphate was ultrasonically dispersed in ethanol, then 0.5 g of epichlorohydrin and 1 g of triethylamine were added, and the mixture was refluxed at 80 °C for 6 h, followed by suction filtration, washing, and drying to obtain epoxy - intercalated zirconium phosphate.

[0031] (3) 8 g of polyethyleneimine (molecular weight 600) was fully stirred and dissolved in deionized water, then 1 g of the obtained epoxy - intercalated zirconium phosphate was added and ultrasonically dispersed evenly. After stirring and reacting at 50 °C for 8 h, the reaction solution was freeze - dried at - 40 °C for 50 h to obtain crosslinked modified exfoliated zirconium phosphate - polyethyleneimine nanocomposite aerogel. The SEM image of the exfoliated zirconium phosphate with surface cross - linked and grafted polyethyleneimine (before freeze - drying) is as Figure 2 shown. It can be seen that polyethyleneimine is cross - linked and grafted on the surface of the nanosheets and connects the dispersed flakes together to form large nanofilms. Moreover, due to effective exfoliation, the cross - linked coverage surface area of polyethyleneimine increases, and the polyethyleneimine grafted on adjacent flakes connects the nanosheets, resulting in a large number of wrinkles. The SEM image of the prepared crosslinked modified exfoliated zirconium phosphate - polyethyleneimine nanocomposite aerogel is as Figure 3 shown. It can be seen that the prepared aerogel has a large number of pore structures.

[0032] The adsorption performance experiment of the crosslinked modified exfoliated zirconium phosphate - polyethyleneimine nanocomposite aerogel prepared in Example 1 is as follows:

[0033] 100 mL of an aqueous solution with a lead ion (lead nitrate as the reagent) concentration of 100 mg / L was prepared in a flask. After adjusting the pH of the solution to 7 with 0.1 M NaOH, the prepared crosslinked modified exfoliated zirconium phosphate - polyethyleneimine nanocomposite aerogel was added, and then the mixture was adsorbed at 30 °C in a constant temperature shaker at a rotation speed of 200 rpm for 3 h. After adsorption, the supernatant was taken, and the concentration of lead ions in the supernatant was measured by ICP - OES. The adsorption amount of the adsorption material for lead ions was calculated by the following formula ( Q, mg / g), and the results are listed in Table 1.

[0034] Q = ([[]]END]] C 0 - C t ) V / M ,

[0035] wherein, Q is the adsorption capacity (mg / g); C 0 is the initial concentration of heavy metal ions (mg / L); C t is the concentration of heavy metal ions after adsorption (mg / L); V is the volume of the solution (L); M is the mass of the adsorbent (g).

[0036] Example 2

[0037] A preparation method of crosslinked modified exfoliated zirconium phosphate-polyethyleneimine nanocomposite aerogel, comprising the following steps:

[0038] (1) Ultrasonically disperse 1 g of α-zirconium phosphate (13772-29-7, Shanghai Aladdin Reagent Co., Ltd.) in deionized water, then slowly add 54 mL of an aqueous solution of mercaptoethylamine with a concentration of 13 mg / mL, and carry out an intercalation reaction for 6 h under the action of 50 kHz ultrasonic waves, followed by suction filtration, washing, and drying to obtain mercapto-functionalized intercalated zirconium phosphate.

[0039] (2) Ultrasonically disperse 1 g of the obtained mercapto-functionalized intercalated zirconium phosphate in ethanol, then add 0.75 g of epichlorohydrin and 1.5 g of pyridine, and reflux and react at 85 °C for 5 h, followed by suction filtration, washing, and drying to obtain epoxy-functionalized intercalated zirconium phosphate.

[0040] (3) Thoroughly stir and dissolve 14 g of polyethyleneimine (molecular weight 600) in deionized water, then add 1 g of the obtained epoxy-functionalized intercalated zirconium phosphate, ultrasonically disperse it evenly, stir and react at 65 °C for 7 h, and then freeze-dry the reaction solution at -45 °C for 40 h to obtain crosslinked modified exfoliated zirconium phosphate-polyethyleneimine nanocomposite aerogel. Its adsorption performance is measured according to the adsorption performance experiment of the product in Example 1, and the results are listed in Table 1.

[0041] Example 3

[0042] A preparation method of crosslinked modified exfoliated zirconium phosphate-polyethyleneimine nanocomposite aerogel, comprising the following steps:

[0043] (1) 1 g of α-zirconium phosphate (13772-29-7, Shanghai Aladdin Reagent Co., Ltd.) was ultrasonically dispersed in deionized water, and then an aqueous solution of 50 mL of mercaptoethylamine with a concentration of 16 mg / mL was slowly added dropwise. Under the action of 60 kHz ultrasonic waves, an intercalation reaction was carried out for 5 h, followed by suction filtration, washing, and drying to obtain mercapto-intercalated zirconium phosphate.

[0044] (2) 1 g of the obtained mercapto-intercalated zirconium phosphate was ultrasonically dispersed in ethanol, and then 1 g of epichlorohydrin and 2 g of triethylamine were added. The mixture was refluxed at 90 °C for 4 h, followed by suction filtration, washing, and drying to obtain epoxy-intercalated zirconium phosphate.

[0045] (3) 20 g of polyethyleneimine (molecular weight 600) was fully stirred and dissolved in deionized water, and then 1 g of the obtained epoxy-intercalated zirconium phosphate was added. After ultrasonic dispersion to uniformity, the mixture was stirred at 80 °C for 6 h. Then, the reaction solution was freeze-dried at -50 °C for 30 h to obtain a crosslinked and modified exfoliated zirconium phosphate-polyethyleneimine nanocomposite aerogel. Its adsorption performance was measured according to the adsorption performance experiment of the product in Example 1, and the results are listed in Table 1.

[0046] Comparative Example 1

[0047] 8 g of polyethyleneimine (molecular weight 600) was fully stirred and dissolved in deionized water, and then 1 g of untreated zirconium phosphate was added. After ultrasonic dispersion to uniformity, the mixture was stirred at 50 °C for 8 h. Then, the reaction solution was freeze-dried at -40 °C for 50 h to obtain a zirconium phosphate-polyethyleneimine composite aerogel. Its adsorption performance was measured according to the adsorption performance experiment of the product in Example 1, and the results are listed in Table 1.

[0048] Comparative Example 2

[0049] 8 g of polyethyleneimine (molecular weight 600) was fully stirred and dissolved in deionized water, and then 1 g of mercapto-intercalated zirconium phosphate (prepared according to step (1) in Example 1) was added. After ultrasonic dispersion to uniformity, the mixture was stirred at 50 °C for 8 h. Then, the reaction solution was freeze-dried at -40 °C for 50 h to obtain a mercapto-intercalated zirconium phosphate-polyethyleneimine composite aerogel. Its adsorption performance was measured according to the adsorption performance experiment of the product in Example 1, and the results are listed in Table 1.

[0050] Table 1 Adsorption capacity of the aerogels prepared in Examples 1-3 and Comparative Examples 1-2 for lead ions

[0051]

[0052] It can be seen from the results that the crosslinked modified exfoliated zirconium phosphate-polyethyleneimine nanocomposite aerogel prepared in the embodiment of the present invention has excellent adsorption performance for lead ions with an adsorption capacity of up to 349 mg / g due to its rich pore structure, perfect combination and synergistic effect of the excellent structural properties of exfoliated zirconium phosphate and the rich active amino groups contained in polyethyleneimine.

[0053] In the aerogels prepared in Comparative Example 1 and Comparative Example 2, the interlayer of zirconium phosphate was not crosslinked and grafted and exfoliated. Not only could the more excellent properties of exfoliated zirconium phosphate not be exerted, but also only weak hydrogen bond interfacial binding forces were formed between the polyethyleneimine matrix and the surface and edges of zirconium phosphate, resulting in poor interfacial compatibility between the two and unable to fully exert the synergistic adsorption enhancement effect of the two. In addition, a large number of hydroxyl groups with excellent adsorption performance were introduced during the crosslinking process, which could further improve the adsorption performance of the composite aerogel for heavy metal ions. Therefore, the aerogels prepared in the comparative examples were far less excellent in heavy metal ion adsorption performance than the nanocomposite aerogel prepared in the example.

Claims

1. A method for preparing a cross-linked modified exfoliated zirconium phosphate-polyethyleneimine nanocomposite aerogel, characterized in that: The following steps are involved: (1) Using mercaptoethylamine as a guest molecule, α-zirconium phosphate is intercalated to obtain thiolated intercalated zirconium phosphate; (2) modifying the surface and interlayer of the thiol-intercalated zirconium phosphate with epichlorohydrin through a substitution reaction between thiol groups and chlorine atoms to obtain an epoxy-intercalated zirconium phosphate; (3) Ultrasonic dispersion of the epoxylated intercalated zirconium phosphate in an aqueous solution of polyethyleneimine for crosslinking modification and exfoliation reaction, using the epoxylated intercalated zirconium phosphate as a crosslinking agent to crosslink and graft polyethyleneimine on the surface and between layers of the zirconium phosphate, and finally freeze-drying the reaction solution to obtain a crosslinked, modified, exfoliated zirconium phosphate-polyethyleneimine nanocomposite aerogel.

2. According to the method for preparing the cross-linked modified exfoliated zirconium phosphate-polyethyleneimine nanocomposite aerogel according to claim 1, the step (1) specifically comprises ultrasonically dispersing α-zirconium phosphate in deionized water, then slowly dropping an aqueous solution of mercaptoethylamine to carry out an intercalation reaction, filtering, washing, and drying.

3. The method for preparing the cross-linked modified exfoliated zirconium phosphate-polyethyleneimine nanocomposite aerogel according to claim 2, wherein the mass ratio of α-zirconium phosphate to mercaptoethylamine is 1:(0.6-0.8), and the concentration of the mercaptoethylamine aqueous solution is 10-16 mg / mL.

4. The method for preparing the cross-linked modified exfoliated zirconium phosphate-polyethyleneimine nanocomposite aerogel according to claim 2, wherein the intercalation reaction in step (1) is carried out under the action of 40-60 kHz ultrasonic waves for 5-7 hours.

5. The method for preparing the cross-linked modified exfoliated zirconium phosphate-polyethyleneimine nanocomposite aerogel according to claim 1, wherein the step (2) specifically comprises ultrasonically dispersing the thiolated intercalated zirconium phosphate in ethanol, then adding epichlorohydrin and an acid binding agent, stirring to react, filtering, washing, and drying.

6. The method for preparing the cross-linked modified exfoliated zirconium phosphate-polyethyleneimine nanocomposite aerogel according to claim 5, wherein the mass ratio of the thiolated intercalated zirconium phosphate, epichlorohydrin and the acid binding agent is 1:(0.5-1):(1-2), and the acid binding agent is one of triethylamine and pyridine.

7. The method for preparing the cross-linked modified exfoliated zirconium phosphate-polyethyleneimine nanocomposite aerogel according to claim 5, wherein the stirring reaction in step (2) is refluxed at 80-90°C for 4-6 hours.

8. The method for preparing the cross-linked modified exfoliated zirconium phosphate-polyethyleneimine nanocomposite aerogel according to claim 1, wherein the mass ratio of the epoxy-intercalated zirconium phosphate to the polyethyleneimine in step (3) is 1:(8-20).

9. The method for preparing the cross-linked modified exfoliated zirconium phosphate-polyethyleneimine nanocomposite aerogel according to claim 1, wherein the cross-linking modification and exfoliation reaction in step (3) is carried out at 50-80°C with stirring for 6-8 hours.

10. The method for preparing the cross-linked modified exfoliated zirconium phosphate-polyethyleneimine nanocomposite aerogel according to claim 1, wherein the freeze drying in step (3) is to freeze dry the reaction solution at -50 to -40°C for 30 to 50 hours.

Images