Composite super absorbent resin based on chabazite molecular sieve and preparation method thereof

Abstract

The invention discloses a chabazite molecular sieve-based composite super absorbent resin and a preparation method thereof. The preparation method comprises the following preparation steps: S1, preparing a Na-type chabazite molecular sieve; s2, carrying out ammonium exchange treatment on the Na-type chabazite molecular sieve, filtering, washing, drying and roasting to obtain an H-type chabazite molecular sieve; s3, uniformly mixing the H-type chabazite molecular sieve, acrylic acid, an initiator, a cross-linking agent and a dispersing agent in deionized water, pouring the mixture into a high-pressure reaction kettle, and carrying out polymerization reaction under the protection of N2; and S4, pouring out the oil-phase medium, separating out a reaction product, sequentially leaching and dehydrating the product by using deionized water, absolute methanol and absolute ethyl alcohol, and drying the obtained solid to constant weight, thereby obtaining the composite super absorbent resin product based on the chabazite molecular sieve. According to the prepared composite super absorbent resin material based on the chabazite molecular sieve, the water absorption rate is larger than or equal to 56 g / g, the 0.3 psi pressurized absorption amount is larger than or equal to 25 g / g, the gel strength is 3000 N / kg-3900 N / kg, and the ammonia removal rate is larger than or equal to 74%.

Description

Technical Field

[0001] This invention relates to the field of composite material synthesis technology, specifically to a method for preparing a novel composite superabsorbent resin material based on hydrogen-type chalcogenide molecular sieves. Background Technology

[0002] Superabsorbent polymer (SAP) is a functional polymer material with a three-dimensional cross-linked network structure. It absorbs water but is insoluble in water or common organic solvents, capable of absorbing tens or even thousands of times its own weight in water in a short time, and exhibiting excellent water retention. Its high absorbency primarily stems from the large number of hydrophilic functional groups on its polymer chains, such as hydroxyl, carboxyl, and amino groups. Due to its hydrophilic swelling and water retention capabilities, SAP is currently widely used in hygiene products, agriculture, construction, and biomedicine. Compared to traditional absorbent materials such as sponges, silicone, activated carbon, and absorbent cotton, SAP materials offer advantages such as high absorbency, fast absorption rate, strong water retention, moderate price, and good safety, making it highly commercially valuable for use in personal care products such as baby and adult diapers. Based on this, many research institutions focus on improving the absorbency and water retention properties of SAP materials, for example, by using polymeric derivatives of acrylic acid (AA), polyacrylic acid (PAA), and acrylamide (AM) and designing different cross-linking densities in the substrates to enhance absorbency and water retention.

[0003] The prior art has been disclosed as follows: CN117778100A discloses a micron-sized temperature-controlled sustained-release fragrance microcapsule and its preparation method. The fragrance microcapsule is formed from a Pickering emulsion. The Pickering emulsion includes a core material and a wall material; the core material is a fragrance, and the wall material is a biodegradable polymer. The Pickering emulsion comprises the following components in parts by weight: 0.1–0.3 parts boron nitride nanosheets; 1–5 parts regenerated nanocellulose; 30–40 parts hydrophobic organic phase change material; 10–20 parts biodegradable polymer; 0.1–0.2 parts cationic surfactant; and 600–1000 parts organic solvent. This micron-sized temperature-controlled sustained-release fragrance microcapsule not only possesses high stability, effectively reducing demulsification during the later stages of microcapsule preparation, but also allows for controlled release of the fragrance based on temperature changes, making it suitable for certain specific applications.

[0004] It is important to note that traditional superabsorbent polymers (SAPs) typically exhibit low gel strength after absorbing water and salt; some products even tend to form flowing gels after water absorption, limiting their water absorption capacity under pressure. Existing technologies have attempted to improve the gel strength of polyacrylamide SAPs by adding specific amounts of bentonite and kaolin; or by using potassium chloride to control the system viscosity, synthesizing a SAP that can improve the gel strength of the absorbent. While these methods can increase gel strength, the limited mechanical strength of the inorganic powders used limits their overall improvement.

[0005] On the other hand, the deodorization effect is also one of the important performance indicators of superabsorbent polymer (SAP) materials. Conventional SAP materials use physical adsorption and masking to adsorb and fix NH3 molecules, thereby reducing or eliminating odors; or they add fragrance additives to mask odors and achieve deodorization. However, physical adsorption relies on van der Waals forces, which have weak adsorption energy and are prone to desorption, thus their removal effect on ammonia, sulfides, mercaptans, etc. is not ideal.

[0006] In summary, there is an urgent need for a superabsorbent resin that can combine pressurized water absorption performance with ammonia removal and deodorization effects. Summary of the Invention

[0007] To address the aforementioned shortcomings of existing technologies, this invention provides a novel composite superabsorbent resin that can simultaneously improve pressurized water absorption performance and ammonia removal and deodorization effects.

[0008] This composite material leverages the highly ordered three-dimensional pore structure of chabazite molecular sieves, their excellent hydrothermal stability under high temperature and pressure, and abundant Si-OH hydrophilic groups to solve the problems of insufficient gel strength and unsatisfactory pressure resistance and water absorption performance of traditional superabsorbent resins. Simultaneously, the abundant acidic sites on the surface of the ammonium-exchanged hydrogen-form chabazite molecular sieve exhibit excellent adsorption capacity for alkaline gases such as NH3, thus addressing the technical problem of poor ammonia removal and deodorization effects in traditional superabsorbent resins. Ultimately, this achieves a simultaneous improvement in both pressure resistance and water absorption performance, as well as ammonia removal and deodorization capabilities.

[0009] To achieve the above objectives, the following technical solutions are used: A method for preparing a composite superabsorbent resin based on chalcogenide molecular sieve includes the following preparation steps: S1 was prepared by hydrothermal crystallization, followed by filtration, washing, drying, and calcination to obtain Na-type chalcogenide molecular sieve; S2 was subjected to ammonium exchange treatment on Na-type chalcogenide molecular sieve, and after filtration, washing, drying and calcination, H-type chalcogenide molecular sieve was obtained. S3 involves uniformly mixing H-type zeolite molecular sieve, acrylic acid, initiator, crosslinking agent, and dispersant in deionized water, then pouring the mixture into a high-pressure reactor and carrying out the polymerization reaction under N2 protection. After pouring out the oil phase medium in S4 and separating the reaction product, the product is washed and dehydrated sequentially with deionized water, anhydrous methanol, and anhydrous ethanol. The resulting solid is dried to constant weight to obtain the composite superabsorbent resin product based on zeolite molecular sieve.

[0010] As a further improvement to this scheme, the hydrothermal crystallization conditions described in S1 are as follows: A silicon source, an aluminum source, a phosphorus source, a template agent, and deionized water are mixed and stirred at 20-30°C to form a gel precursor. The gel precursor is then transferred to a reaction vessel for crystallization, filtration, washing, drying, and calcination to obtain Na-type chalcogenide molecular sieve.

[0011] As a further improvement to this scheme, the Na-type chalcogenide molecular sieve described in S1 is one or more of SSZ-13, SAPO-34, and SAPO-47.

[0012] As a further improvement to this scheme, the molar ratio of Si to Al in the Na-type chalcogenide molecular sieve described in S1 is 0.5~30.

[0013] As a further improvement to this scheme, the ammonium exchange conditions described in S2 are as follows: The Na-type chalcogenide molecular sieve was treated with a 1 mol / L ammonium salt solution, stirred at 60℃ for 6 h, centrifuged and filtered, washed with water, dried at 80℃, and calcined at 500~600℃ for 2~5 h.

[0014] As a further improvement to this scheme, the ammonium salt mentioned in S2 is one or more of ammonium chloride, ammonium nitrate, and ammonium sulfate; The initiator described in S3 is one or more of ammonium persulfate, potassium persulfate, hydrogen peroxide, and benzoyl peroxide; The crosslinking agent described in S3 is one or more of N,N-dimethylbisacrylamide, N-hydroxymethylpropylene, ethylenediamine, divinylbenzene, and divinyltoluene.

[0015] As a further improvement to this scheme, the dispersant mentioned in S3 is one or more of hexadecyl phosphate monoester, octadecyl phosphate monoester, polyoxyethylene nonylphenol, or triethylene glycol.

[0016] As a further improvement to this scheme, the mass ratio of hydrogen-type chalcogenide molecular sieve, acrylic acid, initiator, crosslinking agent, and dispersant in S3 is 1~15: 100: 0.1~2: 0.1~5: 2~5.

[0017] As a further improvement to this scheme, the polymerization reaction conditions described in S3 are as follows: reaction temperature is 60~90 ℃, and reaction time is 4~8 h.

[0018] As a further improvement to this scheme, during the S3 separation and cleaning process, the S3 is soaked in anhydrous methanol for 2-5 hours to dehydrate, and then rinsed with anhydrous ethanol 2-3 times to remove excess anhydrous methanol.

[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention proposes a method for preparing a novel composite superabsorbent resin material based on zeolite molecular sieve, which can provide a stable skeleton support and abundant Si-OH hydrophilic groups for the superabsorbent resin, enhance its gel strength after pressure water absorption, and realize the product's high-efficiency pressure absorption performance.

[0020] (2) The surface of the hydrogen-type zeolite molecular sieve after ammonium exchange has abundant acidic sites. When combined with superabsorbent resin, it can achieve highly selective chemical adsorption of NH3 molecules (alkaline gas), thereby greatly improving the ammonia removal performance. This can solve the technical problem that traditional SAP materials have weak adsorption capacity for NH3 and unsatisfactory deodorization effect.

[0021] (3) The novel composite superabsorbent resin material based on zeolite molecular sieve prepared has a water absorption ratio ≥56 g / g, a pressure absorption of ≥25 g / g at 0.3 psi, a gel strength of 3000 N / kg ~ 3900 N / kg, and an ammonia removal rate ≥74%.

[0022] (4) The preparation method of the novel composite superabsorbent resin material based on zeolite molecular sieve described in this invention is simple, easy to implement, low in cost, and conducive to industrial production. The product has the advantages of high gel strength, strong pressure resistance and water absorption capacity, and good ammonia removal effect. It can quickly absorb human secretions and has broad application prospects in the field of disposable hygiene products. Attached Figure Description

[0023] Figure 1 The XRD patterns of SAPO-34 and SSZ-13 molecular sieves obtained in Examples 1 and 4 show that they all exhibit typical chamaeziolith (CHA) topological crystal phases.

[0024] Figure 2 The N2 physical adsorption / desorption curve of the SSZ-13 molecular sieve obtained in Example 4 is shown in the figure. The adsorption isotherm is of type I. As can be seen from the figure, the molecular sieve has a rich microporous structure.

[0025] Figure 3 The image shows the SEM image of the SSZ-13 molecular sieve obtained in Example 4.

[0026] Figure 4The image shows the ammonia temperature-programmed desorption curve (NH3-TPD) of the SAPO-34 molecular sieve obtained in Example 1. The NH3-TPD curve shows that the SAPO-34 molecular sieve obtained in Example 1 exhibits NH3 desorption peaks at 192℃ and 460℃, indicating that it possesses abundant strong acid and weak acid centers.

[0027] Figure 5 This is a SEM image of the superabsorbent resin material in Example 1.

[0028] Figure 6 This is a product image of the superabsorbent resin material used in Example 1. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described below in conjunction with the embodiments and accompanying drawings.

[0030] Example 1 (1) Tetraethyl orthosilicate (based on the molar amount of SiO2), sodium aluminate (based on the molar amount of Al2O3), phosphoric acid (based on the molar amount of P2O5), tetraethylammonium hydroxide, and deionized water were mixed in a molar ratio of n(SiO2):n(Al2O3):n(P2O5):n(TEAOH):n(H2O) = 1:1.5:2:3:40 and stirred at room temperature to form a gel precursor. The gel precursor was transferred to a reaction vessel and crystallized at 180°C for 72 h. The solid product was filtered, washed, dried at 80°C for 12 h, and calcined at 560°C for 4 h to remove the template agent, thus obtaining Na-type SAPO-34 molecular sieve. (2) Treat it with 1 mol / L NH4NO3 solution, stir at 60 °C for 6 hours, centrifuge and filter, wash with water, dry at 80 °C for 12 hours, and calcine at 560 °C for 4 hours to obtain H-type SAPO-34 molecular sieve. (3) 10 g H-type SAPO-34 molecular sieve, 100 g acrylic acid, 1 g ammonium persulfate, 2 g N,N-dimethylbisacrylamide and 5 g hexadecyl phosphate monoester were added to 200 mL of deionized water and mixed evenly. The mixture was then poured into a high-pressure reactor and reacted at 80 °C for 8 h. N2 was continuously introduced for protection during the reaction. (4) Pour out the oil phase medium, separate the reaction product, wash with deionized water, soak in anhydrous methanol for 5 hours, rinse with anhydrous ethanol 3 times, and dry the obtained solid at 80°C to constant weight to obtain the composite superabsorbent resin product based on H-type SAPO-34 molecular sieve.

[0031] Example 2 (1) Silica sol (based on the molar amount of SiO2), sodium aluminate (based on the molar amount of Al2O3), phosphoric acid (based on the molar amount of P2O5), tetraethylammonium hydroxide, and deionized water were mixed in a molar ratio of n(SiO2):n(Al2O3):n(P2O5):n(TEAOH):n(H2O) = 1:0.5:0.8:2:15 and stirred at room temperature to form a gel precursor. The gel precursor was transferred to a reaction vessel and crystallized at 200°C for 48 h. The solid product was filtered, washed, and dried at 100°C for 12 h to obtain Na-type SAPO-34 molecular sieve precursor. (2) Treat it with 1 mol / L NH4Cl solution, stir at 60 °C for 6 hours, centrifuge and filter, wash with water, dry at 80 °C, and calcine at 600 °C for 4 hours to obtain H-type SAPO-34 molecular sieve; (3) Add 2 g H-type SAPO-34 molecular sieve, 100 g acrylic acid, 1 g hydrogen peroxide, 1 g ethylenediamine, and 5 g polyoxyethylene nonylphenol to 200 mL of deionized water, mix them evenly, and pour them into a high-pressure reactor. React at 60°C for 4 h, and continuously introduce N2 for protection during the reaction. (4) Pour out the oil phase medium, separate the reaction product, wash with deionized water, soak in anhydrous methanol for 3 hours, rinse twice with anhydrous ethanol, and dry the obtained solid at 80°C to constant weight to obtain the composite superabsorbent resin product based on H-type SAPO-34 molecular sieve.

[0032] Example 3 (1) Sodium silicate (based on the molar amount of SiO2), aluminum isopropoxide (based on the molar amount of Al2O3), phosphoric acid (based on the molar amount of P2O5), triethylamine, and deionized water were mixed in a molar ratio of n(SiO2):n(Al2O3):n(P2O5):n(TEA):n(H2O) = 1:2:2:12:22 and stirred at room temperature to form a gel precursor. The gel precursor was transferred to a reaction vessel and crystallized at 190°C for 48 h. The solid product was filtered, washed, dried at 90°C for 10 h, and calcined at 550°C for 6 h to obtain Na-type SAPO-47 molecular sieve. (2) Treat it with 1 mol / L NH4NO3 solution, stir at 60℃ for 6 hours, centrifuge and filter, wash with water, dry at 80℃, and calcine at 550℃ for 2 hours to obtain H-type SAPO-47 molecular sieve. (3) Add 5 g H-type SAPO-47 molecular sieve, 100 g acrylic acid, 0.5 g ammonium persulfate, 0.5 g potassium persulfate, 0.2 g N-hydroxymethylpropene and 1.5 g octadecyl phosphate monoester to 200 mL of deionized water, mix evenly, and pour into a high-pressure reactor. React at 80℃ for 6 h, and continuously introduce N2 for protection during the reaction. (4) Pour out the oil phase medium, separate the reaction product, wash with deionized water, soak in anhydrous methanol for 4 hours, rinse with anhydrous ethanol 3 times, and dry the obtained solid at 80°C to constant weight to obtain the composite superabsorbent resin product based on H-type SAPO-47 molecular sieve.

[0033] Example 4 (1) Silica sol (based on the molar amount of SiO2), sodium aluminate (based on the molar amount of Al2O3), N,N,N-trimethyladamantane ammonium (TMADa+) tetrapropylammonium hydroxide and deionized water were mixed in a molar ratio of n(SiO2):n(Al2O3):n(TMADa+):n(H2O) = 1:0.025:0.2:30 and stirred at room temperature to form a gel precursor. The gel precursor was transferred to a reaction vessel and crystallized at 160℃ for 96 h. The solid product was filtered, washed and dried at 80℃ for 12 h to obtain Na-type SSZ-13 molecular sieve precursor. (2) Subsequently, it was treated with 1 mol / L NH4NO3 solution, stirred at 60°C for 6 hours, centrifuged and filtered, washed with water, dried at 80°C, and calcined at 560°C for 4 hours to obtain H-type SSZ-13 molecular sieve. In this embodiment, steps (3) and (4) are the same as in embodiment 1.

[0034] Comparative Example 1 The superabsorbent resin in this embodiment is made from the following raw materials in the following proportions: 10 g of hydrogen-form SAPO-34 molecular sieve, 100 g of acrylic acid, 1 g of ammonium persulfate, and 2 g of N,N-dimethylbisacrylamide were mixed. The superabsorbent resin of chalcogenide SAPO-34 molecular sieve without dispersant was prepared according to steps (3) and (4) of Example 1.

[0035] Comparative Example 2 The superabsorbent resin in this embodiment is made from the following raw materials in the following proportions: A highly absorbent resin containing sodium-type SAPO-47 molecular sieve was prepared by mixing 5 g of sodium-type SAPO-47 molecular sieve, 100 g of acrylic acid, 0.5 g of ammonium persulfate, 0.5 g of potassium persulfate, 0.2 g of N-hydroxymethylpropene, and 1.5 g of octadecyl phosphate monoester, following steps (3) and (4) of Example 3.

[0036] Comparative Example 3 The superabsorbent resin in this embodiment is made from the following raw materials in the following proportions: 100 g of acrylic acid, 0.5 g of ammonium persulfate, 0.5 g of potassium persulfate, 0.2 g of N-hydroxymethylpropene, and 1.5 g of octadecyl phosphate monoester were mixed. A superabsorbent resin without zeolite molecular sieve was prepared according to steps (3) and (4) of Example 3.

[0037] Absorption performance test The molecular sieve hybrid superabsorbent resin composites prepared in Examples 1-4 and the molecular sieve-free superabsorbent resins prepared in Comparative Examples 1-2 were tested according to standard ASTM D570-1998(2010)e1 for their respective water absorption ratio, absorption capacity under 0.3 psi pressure, and gel strength. The test results are shown in Table 1. Table 1. Absorption performance test results of different samples

[0038] As shown in Table 1, the composite superabsorbent resins based on chalcogenide molecular sieves prepared in Examples 1-4 of this invention exhibit higher water absorption ratios, absorption capacities at 0.3 psi pressure, and gel strengths than the superabsorbent resins without molecular sieves prepared in Comparative Examples 1-2. Furthermore, the absorption capacities at 0.3 psi pressure and gel strength of the products increase with increasing chalcogenide molecular sieve content, confirming the stable framework structure and abundant pores of the chalcogenide molecular sieve under high temperature and pressure, which can solve the technical problems of insufficient gel strength and unsatisfactory pressure-resistant water absorption performance of traditional superabsorbent resins.

[0039] Ammonia removal performance test: The molecular sieve and superabsorbent resin composite materials prepared in Examples 1-4, and the superabsorbent resin without molecular sieve prepared in Comparative Examples 1-2 were subjected to ammonia removal performance tests. The test results are shown in Table 2. The specific test methods are as follows: Take 5 g of each of the test samples prepared in Examples 1-4 and Comparative Examples 1-2.

[0040] Seven PVF resin gas bags were prepared. Test samples were placed in six of the gas bags, with the remaining bag serving as a blank. Then, 500 ppm of NH3 was introduced into each of the seven gas bags and sealed. After 1 hour, the concentration of NH3 in the gas bags was measured using a gas detection tube. The test results are as follows: Table 2. Results of ammonia removal performance tests on different samples

[0041] As can be seen from the performance test results in Table 2, the present invention combines different zeolite molecular sieve powders with superabsorbent resins in the raw material formulation for preparing the absorbent material, enabling the novel composite absorbent material of the present invention to adsorb and neutralize alkaline substances, such as ammonia. Therefore, the molecular sieve and superabsorbent resin composite materials prepared in Examples 1-4 of the present invention have excellent ammonia removal and deodorization effects.

[0042] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent modifications made using the present invention are within the patent protection scope of the present invention.

Claims

1. A method for preparing a composite superabsorbent resin based on chalcogenide molecular sieve, characterized in that, The preparation steps include the following: S1 was prepared by hydrothermal crystallization, followed by filtration, washing, drying, and calcination to obtain Na-type chalcogenide molecular sieve; S2 was subjected to ammonium exchange treatment on Na-type chalcogenide molecular sieve, and after filtration, washing, drying and calcination, H-type chalcogenide molecular sieve was obtained. S3 involves uniformly mixing H-type zeolite molecular sieve, acrylic acid, initiator, crosslinking agent, and dispersant in deionized water, then pouring the mixture into a high-pressure reactor and carrying out the polymerization reaction under N2 protection. After pouring out the oil phase medium in S4 and separating the reaction product, the product is washed and dehydrated sequentially with deionized water, anhydrous methanol, and anhydrous ethanol. The resulting solid is dried to constant weight to obtain the composite superabsorbent resin product based on zeolite molecular sieve.

2. The method for preparing a composite superabsorbent resin based on chalcogenide molecular sieve according to claim 1, characterized in that, The hydrothermal crystallization conditions described in S1 are as follows: A silicon source, an aluminum source, a phosphorus source, a template agent, and deionized water are mixed and stirred at 20-30°C to form a gel precursor. The gel precursor is then transferred to a reaction vessel for crystallization, filtration, washing, drying, and calcination to obtain Na-type chalcogenide molecular sieve.

3. The method for preparing a composite superabsorbent resin based on chalcogenide molecular sieve according to claim 1, characterized in that, The Na-type chalcogenide molecular sieve described in S1 is one or more of SSZ-13, SAPO-34, and SAPO-47.

4. The method for preparing a composite superabsorbent resin based on chalcogenide molecular sieve according to claim 1, characterized in that, The molar ratio of Si to Al in the Na-type chalcogenide molecular sieve described in S1 is 0.5~30.

5. The method for preparing a composite superabsorbent resin based on chalcogenide molecular sieve according to claim 1, characterized in that, The ammonium exchange conditions described in S2 are as follows: Na-type chalcogenide molecular sieves were treated with a 1 mol / L ammonium salt solution, stirred at 60°C for 6 h, centrifuged and filtered, washed with water, dried at 80°C, and calcined at 500-600°C for 2-5 h.

6. The method for preparing a composite superabsorbent resin based on chalcogenide molecular sieve according to claim 1, characterized in that, The ammonium salt mentioned in S2 is one or more of ammonium chloride, ammonium nitrate, and ammonium sulfate; The initiator described in S3 is one or more of ammonium persulfate, potassium persulfate, hydrogen peroxide, and benzoyl peroxide; The crosslinking agent described in S3 is one or more of N,N-dimethylbisacrylamide, N-hydroxymethylpropylene, ethylenediamine, divinylbenzene, and divinyltoluene.

7. The method for preparing a composite superabsorbent resin based on chalcogenide molecular sieve according to claim 1, characterized in that, The dispersant described in S3 is one or more of hexadecyl phosphate monoester, octadecyl phosphate monoester, polyoxyethylene nonylphenol, or triethylene glycol.

8. A method for preparing a composite superabsorbent resin based on chalcogenide molecular sieve according to claim 1, characterized in that, The mass ratio of the hydrogen-type chalcogenide molecular sieve, acrylic acid, initiator, crosslinking agent, and dispersant described in S3 is 1~15:100:0.1~2:0.1~5:2~5.

9. A method for preparing a composite superabsorbent resin based on chalcogenide molecular sieve according to claim 1, characterized in that, The polymerization reaction conditions described in S3 are as follows: reaction temperature is 60~90 ℃, and reaction time is 4~8 h.

10. A method for preparing a composite superabsorbent resin based on chalcogenide molecular sieve according to claim 1, characterized in that, During the S3 separation and cleaning process, the sample is soaked in anhydrous methanol for 2-5 hours to dehydrate, and then rinsed with anhydrous ethanol 2-3 times to remove excess anhydrous methanol.

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