CN110801816A - Microgel-enhanced double-network hydrogel adsorbent and preparation method and application thereof - Google Patents

Abstract

The invention discloses a microgel-enhanced double-network hydrogel adsorbent, a preparation method and application thereof. The composite gel was synthesized by adding agar, acrylamide and hydroxyethyl acrylate solution, and finally the prepared composite gel was aminated to prepare a microgel-enhanced double-network hydrogel adsorbent. The double-network temperature-sensitive hydrogel adsorbent prepared by the invention has a three-dimensional network porous structure, an interpenetrating structure of the double network, and macromolecular cross-linking of the microgel, which greatly enhances the mechanical properties of the gel, and has relatively high performance. High osmotic pressure, can achieve rapid adsorption of heavy metal ions in solution.

Description

A kind of microgel-enhanced double network hydrogel adsorbent and its preparation method and application

technical field

The invention relates to the technical field of functionalized materials, and more particularly, to a microgel-enhanced double-network hydrogel adsorbent and a preparation method and application thereof.

Background technique

With the advancement of industrial development, the problem of pollution has become increasingly prominent, and more and more scientific researchers are focusing on the field of heavy metal wastewater treatment. Adsorption method is a relatively mature wastewater treatment method. The currently used adsorbents are mainly divided into adsorbents made of inorganic or organic materials, such as activated carbon, polymer chelating resin, etc., but such adsorbents have hydrophobic properties, pore size Due to the problems of small size, low diffusion rate and low adsorption capacity, its application is limited. Although another nano-adsorbent has the advantages of high adsorption capacity and fast adsorption rate, it is difficult to be recycled due to its small size. And it is easy to produce toxic sludge. Therefore, the synthesis and development of an adsorbent with high diffusion rate, high adsorption capacity and recyclability is the focus of scientific research. Hydrogel is a three-dimensional network polymer with high water content, high diffusion rate, and hydrophilicity. It is insoluble in water and easy to separate at the macroscopic level. It has great advantages in the treatment of heavy metal wastewater. However, the mechanical properties of traditional single-network hydrogels are poor, and they are easy to absorb water, swell and rupture in water, which is not conducive to the wastewater treatment process.

Double network hydrogels and nanocomposite hydrogels are two kinds of hydrogels with excellent mechanical properties. Double-network hydrogels are intertwined by two networks with opposite mechanical properties, one soft and tough and the other hard and brittle, resulting in a gel with superior mechanical properties. A nanocomposite gel is a hydrogel reinforced by nanomaterials. Multiple cross-links are formed between nanomaterials and polymer networks through physical or chemical bonds, which has greater advantages over traditional cross-linking agents to form single cross-links, and the resulting hydrogels have higher mechanical properties.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a microgel-enhanced double-network hydrogel adsorbent for the disadvantages of poor mechanical properties, low adsorption efficiency and single functionalization of the existing adsorbent.

Another technical problem to be solved by the present invention is to provide the microgel-enhanced double-network hydrogel adsorbent.

The object of the present invention is achieved through the following technical solutions:

A microgel-enhanced double-network hydrogel adsorbent, the preparation steps comprising:

S1. Preparation of prepolymer: add microorganisms to the monomer solution containing N-isopropylacrylamide, pass nitrogen gas, add crosslinking agent and initiator, and then add sodium dodecylbenzenesulfonate at a certain temperature Stir, react for a certain time, and stop the reaction in an ice-water bath to obtain a prepolymer.

S2. Preparation of composite gel: dissolve the agar in water, add a certain amount of acrylamide and hydroxyethyl acrylate monomers, and finally add the prepolymer prepared by S1 to the agar solution, and polymerize at a certain temperature to obtain a composite gel;

S3. Functional modification modification: adding the synthesized gel to a solution containing triethylenetetramine for reaction to obtain a functionally modified microgel-enhanced double network hydrogel adsorbent.

Further, the substance concentration of the N-isopropylacrylamide monomer described in S1 is 0.5-1.0 mmol/mL.

Further, the content of the microorganism in S1 in the solution is 1-10 wt.% of the mass of N-isopropylpropionamide; preferably, the microorganism is Paecilomyces lilacinus.

Further, S1 is the crosslinking agent N,N-methylenebisacrylamide, and the addition amount of the crosslinking agent is 1-10% of the mass of the N-isopropylacrylamide monomer.

Further, the initiator described in S1 is one or more of ammonium persulfate, potassium persulfate, sodium persulfate, hydrogen peroxide and benzoyl peroxide, and the add-on of the initiator is N-isopropyl propylene 1 to 5% of the mass of the amide monomer.

Further, the mass fraction of the agar in the agar aqueous solution described in S2 is 1-15 wt.%; the volume ratio of the prepolymer prepared in S1 described in S2 to the agar monomer solution is 0.1-2.

Further, the mass ratio of the agar to acrylamide and hydroxyethyl acrylate described in S2 is 1:1-10:1-10.

Further, the molar ratio of triethylenetetramine in the solution of S3 to hydroxyethyl acrylate in the composite gel is 0.5-4:1.

Further, the reaction temperature for preparing the prepolymer in S1 is 60-90°C, and the reaction time is 5-20min; the reaction temperature for preparing the composite gel in S2 is 40-80°C, and the reaction time is 1-5h; The reaction temperature of the S3 functional modification modification is 10-100° C., and the reaction time is 1-5 h.

The microgel-enhanced double-network hydrogel adsorbent prepared according to the above was used for the adsorption of heavy metal ions. Preferably, the microgel-enhanced double-network hydrogel adsorbent is mainly used for the adsorption of lead ions.

Compared with the prior art, the beneficial effects are:

The invention creatively uses the affinity effect between the fungal microorganism and the oxygen-containing group on the polymer chain, so that the polymer chain is entangled with each other, and the strength of the gel is enhanced. In addition, the network structure formed by the polymerization and cross-linking of agar and polyacrylamide-co-hydroxyethyl acrylate in the gel crosses each other to form a three-dimensional porous network structure, which has a high osmotic pressure, which not only improves the hydrogelation of the double network. The mechanical properties of the microspheres can fully expose the adsorption sites on the network structure, improve the adsorption capacity of the microspheres, and realize the rapid adsorption of heavy metal ions in the solution.

The invention adopts N-isopropylacrylamide monomer to polymerize to form a temperature-sensitive gel, which can respond to changes in external temperature. The poly-N-isopropylacrylamide undergoes phase transition with the increase of temperature, resulting in volume shrinkage, and the hydrophilic property changes. Because of the hydrophobicity, the adsorption of heavy metal ions is accelerated according to the macroscopic hydrophobicity of the gel, and the adsorption rate is increased.

The gel prepared by the present invention is aminated and has good adsorption effect on heavy metals. At 25 °C, when the dosage of the double network gel adsorbent is 1 g/L, the maximum adsorption capacity of lead ions is 156.84 mg/g, and it is surprising to find that when the concentration of lead ions is lower than 120 mg/L, the adsorption of lead ions The remaining concentration of the adsorbent is lower than 6mg/L, and the adsorption capacity and adsorption efficiency are much higher than those of conventional adsorbents such as resin and activated carbon. At the same time, when the pH is 2.2, the adsorption rate is 0, and the pH is 4, the adsorption capacity reaches the maximum adsorption capacity, and besides excellent acid resistance, it can also be easily regenerated at a lower pH.

Description of drawings

Fig. 1 is the microgel-enhanced double network hydrogel adsorbent prepared by the present invention;

Fig. 2 is the electron microscope image of the microgel-enhanced double-network hydrogel adsorbent prepared by the present invention;

Fig. 3 is the electron microscope image of the microgel-enhanced double-network hydrogel adsorbent prepared by the present invention.

Detailed ways

The following is further explained and illustrated in conjunction with the examples, but the specific examples do not limit the present invention in any form. Unless otherwise specified, the methods and equipment used in the examples are conventional methods and equipment in the art, and the raw materials used are conventional commercially available raw materials.

Example 1

S1. Preparation of prepolymer: N-isopropylacrylamide monomer is dissolved in water to prepare a solution with a concentration of 1.0 mmol/mL, and 5% of the mass of N-isopropylacrylamide monomer is added to Paecilomyces lilacinus , 1% of the mass of the monomer, the biological cross-linking agent MBA, and 1% of the mass of the monomer of the initiator are mixed, and nitrogen is introduced, and then 10% of the mass of N-isopropylacrylamide is added. Dodecylbenzenesulfonic acid Sodium stirring. The prepared solution was stirred and reacted in a constant temperature water bath at 60°C for 20 min, taken out and placed in an ice water bath to terminate the radical polymerization reaction to obtain a prepolymer.

S2. Preparation of composite gel: Dissolve agar in water to prepare a solution with a mass fraction of 10 wt.% agar, and then add acrylamide and hydroxyethyl acrylate monomers, wherein the mass of agar, acrylamide and hydroxyethyl acrylate monomers The ratio is 1:2:2, and then transferred to a constant temperature water bath at 60 °C, adding 0.5 times the volume of the agar mixed solution volume of the prepolymer solution, mixing evenly, and finally initiating polymerization for 2h to form a composite gel.

S3. Functional modification modification: The gel synthesized by S2 is added to the solution containing triethylenetetramine for reaction. The molar ratio of triethylenetetramine and hydroxyethyl acrylate in the composite gel is 2:1, and the reaction is carried out at 60°C for 2h. Functionally modified microgel-enhanced double-network hydrogel adsorbents were obtained.

Example 2

S1. Preparation of prepolymer: N-isopropylacrylamide monomer is dissolved in water to prepare a solution with a concentration of 0.5 mmol/mL, and 1% of the mass of N-isopropylacrylamide monomer is added to Paecilomyces lilacinus , 1% of the mass of the monomer biocrosslinker MBA and 5% of the mass of the monomer initiator are mixed, and nitrogen is introduced, and then 1% of the mass of N-isopropylacrylamide monomer is added. Dodecylbenzenesulfonic acid Sodium stirring. The prepared solution was stirred and reacted in a constant temperature water bath at 90°C for 5 min, taken out and placed in an ice water bath to terminate the radical polymerization reaction to obtain a prepolymer.

S2. Preparation of composite gel: Dissolve agar in water to prepare a solution with a mass fraction of agar of 1 wt.%, then add acrylamide and hydroxyethyl acrylate monomers, wherein the mass of agar, acrylamide and hydroxyethyl acrylate monomers The ratio is 1:10:5, then transferred to a constant temperature water bath at 80 °C, added with a prepolymer solution of 0.1 times the volume of the agar mixed solution, mixed evenly, and finally initiated polymerization for 1 h to form a composite gel.

S3. Functional modification modification: The gel synthesized by S2 is added to the solution containing triethylenetetramine for reaction, the molar ratio of triethylenetetramine to hydroxyethyl acrylate in the composite gel is 0.1:1, and the reaction is carried out at 100 °C for 1 h. Functionally modified microgel-enhanced double-network hydrogel adsorbents were obtained.

Example 3

S1. Preparation of prepolymer: N-isopropylacrylamide monomer is dissolved in water to prepare a solution with a concentration of 1.0 mmol/mL, and 1% of the mass of N-isopropylacrylamide monomer is added. Aspergillus niger, monomer 1% of the mass of the biological cross-linking agent MBA and 10% of the mass of the monomer initiator are mixed, nitrogen is introduced, and then 1% of the mass of N-isopropylacrylamide monomer is added. Sodium dodecyl benzene sulfonate stirs . The prepared solution was stirred and reacted in a constant temperature water bath at 60°C for 20 min, taken out and placed in an ice water bath to terminate the radical polymerization reaction to obtain a prepolymer.

S2. Preparation of composite gel: Dissolve agar in water to prepare a solution with a mass fraction of agar of 1 wt.%, then add acrylamide and hydroxyethyl acrylate monomers, wherein the mass of agar, acrylamide and hydroxyethyl acrylate monomers The ratio is 1:5:10, and then transferred to a constant temperature water bath at 40 °C, adding 1 times the volume of the agar mixed solution volume of the prepolymer solution, mixing evenly, and finally initiating polymerization for 5 hours to form a composite gel.

S3. Functional modification modification: The gel synthesized by S2 was added to the solution containing triethylene tetraamine for reaction. The molar ratio of triethylene tetraamine and hydroxyethyl acrylate in the composite gel was 1:1, and the reaction was performed at 10 °C for 5 hours. Functionally modified microgel-enhanced double-network hydrogel adsorbents were obtained.

Example 4

S1. Preparation of prepolymer: N-isopropylacrylamide monomer is dissolved in water to prepare a solution with a concentration of 1.0 mmol/mL, and 1% of the mass of N-isopropylacrylamide monomer is added to Paecilomyces lilacinus , 1% of the mass of the monomer, the biological cross-linking agent MBA, and 1% of the mass of the monomer of the initiator are mixed, and nitrogen is introduced, and then 10% of the mass of N-isopropylacrylamide is added. Dodecylbenzenesulfonic acid Sodium stirring. The prepared solution was stirred and reacted in a constant temperature water bath at 60°C for 20 min, taken out and placed in an ice water bath to terminate the radical polymerization reaction to obtain a prepolymer.

S2. Preparation of composite gel: Dissolve agar in water to prepare a solution with a mass fraction of 5 wt.% agar, and then add acrylamide and hydroxyethyl acrylate monomers, wherein the mass of agar, acrylamide and hydroxyethyl acrylate monomers The ratio is 1:10:10, and then transferred to a constant temperature water bath at 60 °C, adding 0.5 times the volume of the agar mixed solution volume of the prepolymer solution, mixing evenly, and finally initiating polymerization for 2 hours to form a composite gel.

S3. Functional modification modification: The gel synthesized by S2 is added to the solution containing triethylenetetramine for reaction. The molar ratio of triethylenetetramine and hydroxyethyl acrylate in the composite gel is 2:1, and the reaction is carried out at 60°C for 2h. Functionally modified microgel-enhanced double-network hydrogel adsorbents were obtained.

Example 5

S1. Preparation of prepolymer: N-isopropylacrylamide monomer is dissolved in water to prepare a solution with a concentration of 1.0 mmol/mL, and 1% of the mass of N-isopropylacrylamide monomer is added to Paecilomyces lilacinus , 10% of the mass of the monomer, the biological cross-linking agent MBA, and 1% of the mass of the monomer. Sodium stirring. The prepared solution was stirred and reacted in a constant temperature water bath at 60°C for 20 min, taken out and placed in an ice water bath to terminate the radical polymerization reaction to obtain a prepolymer.

S2. Preparation of composite gel: Dissolve agar in water to prepare a solution with a mass fraction of 15 wt.% agar, and then add acrylamide and hydroxyethyl acrylate monomers, wherein the mass of agar, acrylamide and hydroxyethyl acrylate monomers The ratio is 1:5:2, and then transferred to a constant temperature water bath at 60 °C, adding 1 times the volume of the agar mixed solution volume of the prepolymer solution, mixing evenly, and finally initiating polymerization for 2 h to form a composite gel.

S3. Functional modification modification: The gel synthesized by S2 was added to the solution containing triethylene tetraamine for reaction, the molar ratio of triethylene tetramine and hydroxyethyl acrylate in the composite gel was 4:1, and the reaction was performed at 60 °C for 2 hours. Functionally modified microgel-enhanced double-network hydrogel adsorbents were obtained.

Example 6

S1. Preparation of prepolymer: N-isopropylacrylamide monomer is dissolved in water to prepare a solution with a concentration of 1.0 mmol/mL, and 5% of the mass of N-isopropylacrylamide monomer is added to Paecilomyces lilacinus , 5% of the mass of the monomer, MBA, and the initiator of 3% of the mass of the monomer are mixed, and nitrogen is introduced, and then 10% of the mass of N-isopropylacrylamide is added. Dodecylbenzenesulfonic acid Sodium stirring. The prepared solution was stirred and reacted in a constant temperature water bath at 60°C for 20 min, taken out and placed in an ice water bath to terminate the radical polymerization reaction to obtain a prepolymer.

S2. Preparation of composite gel: Dissolve agar in water to prepare a solution with a mass fraction of 10 wt.% agar, and then add acrylamide and hydroxyethyl acrylate monomers, wherein the mass of agar, acrylamide and hydroxyethyl acrylate monomers The ratio is 1:5:5, and then transferred to a constant temperature water bath at 60°C, adding 1 times the volume of the agar mixed solution volume of the prepolymer solution, mixing evenly, and finally initiating polymerization for 2h to form a composite gel.

S3. Functional modification modification: The gel synthesized by S2 is added to the solution containing triethylenetetramine for reaction. The molar ratio of triethylenetetramine and hydroxyethyl acrylate in the composite gel is 2:1, and the reaction is carried out at 60°C for 2h. Functionally modified microgel-enhanced double-network hydrogel adsorbents were obtained.

Example 7

S1. Preparation of prepolymer: N-isopropylacrylamide monomer is dissolved in water to prepare a solution with a concentration of 1.0 mmol/mL, and 3% of the mass of N-isopropylacrylamide monomer is added to Paecilomyces lilacinus , 5% of the mass of the monomer, the biological cross-linking agent MBA, and 2% of the mass of the monomer of the initiator are mixed, and nitrogen is introduced, and then 8% of the mass of N-isopropylacrylamide is added. Dodecylbenzenesulfonic acid Sodium stirring. The prepared solution was stirred and reacted in a constant temperature water bath at 60°C for 20 min, taken out and placed in an ice water bath to terminate the radical polymerization reaction to obtain a prepolymer.

S2. Preparation of composite gel: Dissolve agar in water to prepare a solution with a mass fraction of agar of 1 wt.%, and then add acrylamide and hydroxyethyl acrylate monomers, wherein the mass of agar, acrylamide and hydroxyethyl acrylate monomers The ratio was 1:2:5, then transferred to a constant temperature water bath at 60 °C, added 1 times the volume of the agar mixed solution volume of the prepolymer solution, mixed evenly, and finally initiated polymerization for 2 h to form a composite gel.

S3. Functional modification modification: The gel synthesized by S2 was added to the solution containing triethylene tetraamine for reaction, the molar ratio of triethylene tetramine and hydroxyethyl acrylate in the composite gel was 4:1, and the reaction was performed at 60 °C for 2 hours. Functionally modified microgel-enhanced double-network hydrogel adsorbents were obtained.

Comparative Example 1

The polyacrylamide-calcium alginate composite microspheres were prepared according to the method described in the application number 201810230011.7.

Comparative Example 2

The process steps of this comparative example are the same as those of the embodiment, and the difference is that the amination modification of steps S2 and S3 is not carried out in this comparative example.

Experimental example 1

The adsorption capacity of the prepared microgel-enhanced double-network hydrogel adsorbent was tested, and the concentrations of heavy metal ion solutions were set to be 30 mg/L, 60 mg/L, 90 mg/L, 120 mg/L, 150 mg/L, and 180 mg/L, respectively. , 210mg/L, 250mg/L, 300mg/L, 350mg/L, 400mg/L, add the microgel-enhanced double network hydrogel adsorbent prepared by the present invention, and the dosage is 1mg/L (gel dry weight) , the pH was 5, the temperature was 20 °C and 40 °C, and the adsorption time was 6 hours. The theoretical adsorption capacity was measured by simulating the Langmuir adsorption isotherm. The test results are shown in Table 1:

Table 1

The compressive properties of the prepared microgel-enhanced double-network hydrogel adsorbent and the hydrogel enhanced by no microgel are shown in Table 2:

Table 2

It can be seen from Table 1 and Table 2 that the microgel-enhanced double-network hydrogel adsorbent prepared by the present invention has better adsorption capacity for lead ions in heavy metal solutions, and has enhanced mechanical properties. Further use the adsorbent prepared in Example 1 to test the adsorption capacity of lead ions. At 25 ° C, the maximum amount of lead ions adsorbed by the microgel-enhanced double network hydrogel adsorbent is 1 g/L, and the maximum adsorption capacity is 156.84. mg/g, and surprisingly found that when the lead ion concentration is lower than 120mg/L, the remaining concentration of lead ions after adsorption is lower than 6mg/L, and the adsorption capacity and adsorption efficiency are much higher than those of conventional resins, activated carbon and other adsorbents . At the same time, at pH 2.2, the adsorption rate is 0, and the adsorption capacity reaches the maximum adsorption capacity at pH 4, the gel has excellent acid resistance and can be easily regenerated at lower pH.

Obviously, the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those of ordinary skill in the art, changes or modifications in other different forms can also be made on the basis of the above description. There is no need and cannot be exhaustive of all implementations here. Any modifications, equivalent replacements and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims (10)

1. a double-network hydrogel adsorbent for microgel-enhancing mechanical properties, is characterized in that, preparation step comprises: S1. Preparation of prepolymer: add microorganisms to the monomer solution containing N-isopropylacrylamide, pass nitrogen gas, add crosslinking agent and initiator, and then add sodium dodecylbenzenesulfonate at a certain temperature Stir, react for a certain period of time, and stop the reaction in an ice-water bath to obtain a prepolymer; S2. Preparation of composite gel: dissolve the agar in water, add a certain amount of hydroxyethyl acrylate monomer, and finally add the prepolymer prepared by S1 to the agar solution, and polymerize at a certain temperature to obtain a composite gel; S3. Functional modification modification: adding the synthesized gel to a solution containing triethylenetetramine for reaction to obtain a functionally modified microgel-enhanced double network hydrogel adsorbent. 2. the double network hydrogel adsorbent that microgel enhances according to claim 1, is characterized in that, the amount concentration of substance of N-isopropylacrylamide monomer described in S1 in solution is 0.5～1.0 mmol/ mL. 3. the double network hydrogel adsorbent that microgel enhances according to claim 1, is characterized in that, the microorganism described in S1 is fungus, and addition is 1～10% of N-isopropyl propionamide quality; Preferably Typically, the microorganism is Paecilomyces lilacinus and/or Aspergillus niger. 4. The microgel-enhanced double-network hydrogel adsorbent of claim 1, wherein the cross-linking agent of S1 is N,N-methylenebisacrylamide, and its addition is N-iso 1~10% of the mass of propylacrylamide monomer. 5. the double network hydrogel adsorbent that microgel strengthens according to claim 1 is characterized in that, the initiator described in S1 is ammonium persulfate, potassium persulfate, sodium persulfate, hydrogen peroxide and benzene peroxide One or more of formyl, and its addition amount is 1~5% of the mass of N-isopropylacrylamide monomer. 6. the double network hydrogel adsorbent that microgel enhances according to claim 1, is characterized in that, the mass fraction of the agar in the agar aqueous solution described in S2 is 1～15wt.%; The volume ratio of polymer to agar monomer solution is 0.1~2. 7. The double network hydrogel adsorbent reinforced by microgel according to claim 1, is characterized in that, the mass ratio of the agar described in S2 to acrylamide, hydroxyethyl acrylate is 1:1～10:1～10 . 8. The double-network hydrogel adsorbent enhanced by microgel according to claim 1, is characterized in that, the double-network hydrogel adsorbent enhanced by microgel according to claim 1, is characterized in that, S3 The molar ratio of triethylenetetramine in the solution to hydroxyethyl acrylate in the composite gel is 0.5-4:1. 9. The microgel-enhanced dual-network hydrogel adsorbent according to claim 1, wherein the S1 prepares a prepolymer reaction temperature of 60 to 90°C, and the reaction time is 5 to 20min; the S2 The reaction temperature for preparing the composite gel is 40-80 °C, and the reaction time is 1-5 h; the reaction temperature for the S3 functional modification modification is 10-100 °C, and the reaction time is 1-5 h. 10. The microgel-enhanced dual-network hydrogel adsorbent according to any one of claims 1 to 9, wherein the microgel-enhanced dual-network hydrogel adsorbent is used for the adsorption of heavy metal ions; Preferably, the microgel-enhanced double network hydrogel adsorbent is used for the adsorption of lead ions.

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