CN110614089A - Preparation method of functionalized polyamide-amine dendrimer adsorbent - Google Patents

Abstract

The invention relates to a preparation method of a functionalized polyamide-amine dendrimer adsorbent, which comprises the following steps: firstly, modifying the 1.0 or 2.0 generation triethoxy silicon-based polyamide-amine dendrimer by adopting methyl isothiocyanate to obtain a functionalized triethoxy silicon-based polyamide-amine dendrimer, and then carrying out sol-gel reaction with tetraethoxysilane according to a specific proportion to obtain the functionalized polyamide-amine dendrimer adsorbent. The adsorbent prepared by the invention contains rich nitrogen, oxygen and sulfur functional groups, has good adsorption performance and adsorption selectivity to Hg (II), and can be used for adsorption separation, selective removal and the like of Hg (II) in water.

Description

A kind of preparation method of functional polyamide-amine dendrimer adsorbent

technical field

The invention relates to a preparation method of a functionalized polyamide-amine tree molecular adsorbent, which belongs to the field of environmental functional materials.

Background technique

With the development of industrialization, the discharge of industrial wastewater has increased, and the water pollution caused by metal ions has become a serious environmental problem. Metal ions are difficult to degrade, are toxic, and cause serious harm to the ecological environment and human body. Therefore, how to effectively remove metal ions in water is of great significance.

Adsorption is widely used for the separation and removal of metal ions due to its simplicity and high efficiency. Polyamide-amine dendrimers contain a large number of nitrogen and oxygen functional groups and intramolecular cavities, which are easy to realize the adsorption and separation of metal ions. Moreover, polyamide-amine dendrimers are easy to be functionalized, and can be modified according to specific requirements to achieve selective adsorption and separation of specific metal ions. However, polyamide-amine dendrimers and metal ion complexes are easily soluble in aqueous solutions and most organic solvents, which greatly limits their application as adsorbents. Immobilizing polyamide-amine dendrimers on specific groups is an effective way to solve this problem. Silica gel has the advantages of good mechanical strength, good thermal and chemical stability, rich pore structure, large specific surface area, and the surface is rich in silanol and easy to modify. It is often used as a material for immobilizing polyamide-amine dendrimers. matrix. At present, there are usually two methods for immobilizing polyamide-amine dendrimers on silica gel, one is to introduce reactive sites on the surface of silica gel, and then gradually synthesize polyamide-amine dendrimers by the divergent method; the other The first is to attach the synthesized polyamide-amine dendrimer to the surface of silica gel through the coupling reaction between functional groups. The first synthesis method is convenient for the separation and purification of products during the synthesis process, but it will lead to the formation of intramolecular and intermolecular cross-linking structures of polyamide-amine dendrimers on the surface of silica gel, and the reduction of silica gel pores. The second method can effectively avoid structural defects inside the polyamide-amine dendrimer, but due to the existence of steric hindrance, it is easy to reduce the loading capacity of the polyamide-amine dendrimer on the surface of silica gel. The above existing problems will lead to the decrease of the adsorption capacity of metal ions by the adsorbent immobilized with higher generation polyamide-amine dendrimers.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a preparation method of a functionalized polyamide-amine dendrimer metal ion adsorbent. The adsorbent prepared by the invention uses sulfur-containing polyamide-amine dendrimers as functional groups, has good binding ability to Hg(II), and can realize effective adsorption and selective separation of Hg(II) in water.

In order to solve the above-mentioned technical problems, the present invention adopts the following technical scheme: a preparation method of functionalized polyamide-amine dendrimer adsorbent, comprising:

Take methyl isothiocyanate, add the 1.0th or 2.0th generation triethoxy silicon-based polyamide-amine dendrimer, use 150-300 ml of absolute ethanol as a solvent, heat and stir the reaction to obtain the 1.0th or 2.0th generation Triethoxy silicon-based sulfur-containing polyamide-amine dendrimers, then cooled to 25°C; then added tetraethyl orthosilicate, water and ammonium fluoride, and continued to stir the reaction. After the reaction, the samples were aged at 50°C After 48 hours, the product was filtered out and extracted with absolute ethanol for at least 12 hours, and dried to obtain the 1.0th or 2.0th generation functionalized polyamidoamine dendrimer adsorbent.

On the basis of the above technical solutions, the present invention can also be improved as follows.

Further, the whole preparation process is carried out under nitrogen protection;

Further, the molar ratio of amino group to methyl isothiocyanate in the 1.0th or 2.0th generation triethoxysilyl polyamide-amine dendrimer is 1: (1.2-6), and the reaction temperature is 50-70 °C, the time is 24-36 hours;

Further, the molar ratio of the 1.0th or 2.0th generation triethoxy silicon-based sulfur-containing polyamide-amine dendrimer to tetraethylorthosilicate, water and ammonium fluoride is 1: (2-10): ( 1-12): (0.01-0.05), the reaction temperature is 25°C, and the reaction time is 24-36 hours.

The 1.0th or 2.0th generation triethoxysilyl-based polyamide-amine dendrimers used in the present invention are obtained by a divergent synthesis method, and the specific preparation method refers to the literature Rongjun Qu, Xilu Ma, Minghua Wang, et al , Journal of Industrial and Engineering Chemistry , 2014, 20: 4382-4392.

The synthesis steps of the 1.0th generation triethoxysilyl amide-amine dendrimer are as follows:

Under nitrogen protection, the methanol solution of 160 milliliters of methyl acrylate (volume ratio is 1:1) is added dropwise in the methanol solution of 150 milliliters of 3-aminopropyltriethoxysilane (volume ratio is 1:1 ), the reaction mixture was stirred at 0°C for 0.5 hour and then raised to 25°C to continue the reaction for 24 hours. After the reaction, use a rotary evaporator to distill off methanol and excess methyl acrylate at 40° C. to obtain the 0.5th generation triethoxysilyl polyamide-amine dendrimer. Subsequently, a methanol solution of the 0.5th generation triethoxysilylpolyamidoamine dendrimer (25 g dissolved in 30 ml of methanol) was added dropwise to a methanol solution of 240 ml of ethylenediamine at 0 °C (1:1 volume ratio), after 0.5 hours of reaction, the temperature was raised to 25°C for 96 hours. After the reaction, use a rotary evaporator to distill off methanol and excess ethylenediamine at 70° C. to obtain the 1.0th generation triethoxysilylamide-amine dendrimer.

The synthesis steps of the 2.0th generation triethoxysilyl amide-amine dendrimer are as follows:

Under nitrogen protection, 40 milliliters of methyl acrylate methanol solution (volume ratio is 1:1) was added dropwise in the methanol solution of the 1.0th generation triethoxysilyl polyamide-amine dendrimer (20 g in 30 ml of methanol), the mixture was stirred at 0°C for 0.5 hour and then continued to react at 25°C for 24 hours. After the reaction, use a rotary evaporator to distill off methanol and excess methyl acrylate at 40° C. to obtain the 1.5th generation triethoxysilyl polyamide-amine dendrimer. Subsequently, a methanol solution of the 1.5th generation triethoxysilyl polyamido-amine dendrimer (12 g dissolved in 15 ml of methanol) was added dropwise to a methanol solution of 100 ml of ethylenediamine at 0 °C (1:1 volume ratio), after 0.5 hours of reaction, the temperature was raised to 25°C for 96 hours. After the reaction, use a rotary evaporator to distill off methanol and excess ethylenediamine at 70° C. to obtain the 2.0th generation triethoxysilylamide-amine dendrimer.

Compared with the prior art, the present invention has the following advantages:

In the functionalized polyamide-amine dendrimer adsorbent prepared by the synthesis method, the polyamide-amine dendrimer has a regular structure, a high content of functional groups, and uniform distribution of adsorption sites, and has good binding to Hg(II). Ability to achieve effective adsorption and selective separation of Hg(II) in water.

Detailed ways

The principles and features of the present invention are described below, and the examples given are only used to explain the present invention, and are not intended to limit the scope of the present invention.

Example 1

Under nitrogen protection, 8 mmoles of the 1.0th generation triethoxysilyl polyamide-amine dendrimer and 24 mmoles of methyl isothiocyanate were added to a 500 ml three-necked flask, followed by 150 ml Anhydrous ethanol was used as a solvent, and the reaction mixture was reacted at 50°C for 36 hours, then cooled to 25°C to obtain the 1.0th generation triethoxysilyl-based sulfur-containing polyamide-amine dendrimer; then 16 mmoles of orthosilicic acid were added Ethyl ester, 8 mmol of water and 0.08 mmol of ammonium fluoride, the reaction mixture was reacted at 25 °C for 24 hours, after the reaction, the sample was aged at 50 °C for 48 hours, the product was filtered out and extracted with absolute ethanol for 12 hours , and dried to obtain the 1.0th functionalized polyamide-amine dendrimer adsorbent.

Example 2

Under nitrogen protection, 8 mmoles of the 1.0th generation triethoxysilyl polyamide-amine dendrimer and 48 mmoles of methyl isothiocyanate were added to a 500 ml three-necked flask, followed by 250 ml Anhydrous ethanol was used as a solvent, and the reaction mixture was reacted at 70°C for 24 hours, then cooled to 25°C to obtain the 1.0th generation triethoxysilyl-based sulfur-containing polyamide-amine dendrimer; then 32 mmoles of orthosilicic acid were added Ethyl ester, 16 mmoles of water and 0.16 mmoles of ammonium fluoride, the reaction mixture was reacted at 25°C for 36 hours, after the reaction, the sample was aged at 50°C for 48 hours, the product was filtered out and extracted with absolute ethanol for 12 hours , and dried to obtain the 1.0th functionalized polyamide-amine dendrimer adsorbent.

Example 3

Under nitrogen protection, 8 mmoles of the 2.0th generation triethoxysilyl polyamide-amine dendrimer and 48 mmoles of methyl isothiocyanate were added to a 500 ml three-necked flask, followed by 250 ml Anhydrous ethanol was used as a solvent, and the reaction mixture was reacted at 60°C for 30 hours, and then cooled to 25°C to obtain the 2.0th generation triethoxysilyl-based sulfur-containing polyamide-amine dendrimers; then 32 mmoles of orthosilicic acid were added Ethyl ester, 24 mmoles of water and 0.16 mmoles of ammonium fluoride, the reaction mixture was reacted at 25°C for 32 hours, after the reaction, the sample was aged at 50°C for 48 hours, the product was filtered out and extracted with absolute ethanol for 12 hours , and dried to obtain the 2.0th functionalized polyamide-amine dendrimer adsorbent.

Example 4

Under nitrogen protection, 8 mmoles of the 2.0th generation triethoxysilyl polyamide-amine dendrimer and 80 mmoles of methyl isothiocyanate were added to a 500 ml three-necked flask, followed by 300 ml Anhydrous ethanol was used as a solvent, and the reaction mixture was reacted at 70°C for 24 hours, then cooled to 25°C to obtain the 2.0th generation triethoxysilyl-based sulfur-containing polyamide-amine dendrimer; 24 mmol orthosilicic acid was then added Ethyl ester, 16 mmoles of water and 0.24 mmoles of ammonium fluoride, the reaction mixture was reacted at 25°C for 24 hours, after the reaction, the sample was aged at 50°C for 48 hours, the product was filtered out and extracted with absolute ethanol for 12 hours , and dried to obtain the 2.0th functionalized polyamide-amine dendrimer adsorbent.

Performance Evaluation 1: The Adsorption Performance of the Functionalized Polyamide-Amine Dendrimer Adsorbent Prepared in Example 2 and Example 3 for Hg(II)

Weigh respectively 20 mg of the 1.0th and 2.0th generation functionalized polyamide-amine dendrimer adsorbents prepared in Example 2 and Example 3, place them in a 100 ml conical flask with a stopper, add 20 ml of 0.001 mol/ One liter of Hg(II) solution was placed in an air bath shaker and shaken at 25°C for 12 hours. The concentration of remaining Hg(II) in the solution was measured with an atomic absorption spectrophotometer, and the Hg(II) ion concentration of the 1.0th and 2.0th generation functionalized polyamide-amine dendrimers was calculated according to the change of Hg(II) ion concentration before and after adsorption. The adsorption amounts of (II) ions were 1.55 and 1.68 mmol/g, respectively.

Performance Evaluation 2: Selective Adsorption of Hg(II) by the Functionalized Polyamide-Amine Dendrimer Adsorbent Prepared in Example 2 and Example 3

Weigh a series of 1.0th and 2.0th generation functionalized polyamidoamine dendrimer adsorbents prepared in Example 2 and Example 3 with a mass of about 20 mg respectively, place them in a 100 ml conical flask with a stopper, and then Add 20 milliliters of ion concentration respectively and all are 0.001 mol/L Hg ( )-Co( ), Hg( )-Pb( ), Hg( )-Mn( ), Hg( )-Ni( ), Hg( )- Fe(III), Hg( )-Cu( ), Hg( )-Cd( ) mixed ion solution, placed in an air bath shaker and shaken at 25°C for 12 hours. Use an atomic absorption spectrophotometer to measure the concentration of remaining Hg(II) and other metal ions in the solution, and calculate the adsorption capacity and selectivity coefficient for Hg(II) and coexisting ions according to the changes in the concentration of metal ions before and after adsorption. , the results are shown in Table 1 and Table 2. It can be seen that the functionalized polyamide-amine dendritic macromolecular adsorbent shows good adsorption selectivity for Hg(II), when Hg( ) and Co( ), Pb( ), Mn( ), Ni( ), Fe(III) ions coexist, and can selectively adsorb Hg(II) with 100%.

Table 1 Selective adsorption of Hg(II) by the 1.0th generation functionalized polyamide-amine dendrimers

Table 2 Selective adsorption of Hg(II) by the 2.0th generation functionalized polyamide-amine dendrimers

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (3)

1. A preparation method of a functionalized polyamide-amine dendrimer adsorbent is characterized by comprising the following steps:

adding 1.0 or 2.0 substituted triethoxysilyl polyamide-amine dendrimer into methyl isothiocyanate, heating and stirring to react by taking 150-300 ml of absolute ethanol as a solvent to prepare 1.0 or 2.0 substituted triethoxysilyl sulfur-containing polyamide-amine dendrimer, and then cooling to 25 ℃; adding tetraethoxysilane, water and ammonium fluoride, continuing stirring for reaction, aging a sample at 50 ℃ for 48 hours after the reaction is finished, filtering a product, extracting the product for at least 12 hours by using absolute ethyl alcohol, and drying to obtain the 1.0 or 2.0 generation functionalized polyamide-amine dendrimer adsorbent.

2. The preparation method according to claim 1, wherein the whole preparation process is carried out under the protection of nitrogen.

3. The method according to claim 1 or 2, wherein the molar ratio of amino group to methyl isothiocyanate in the 1.0 or 2.0 generation triethoxysilylpolyamidoamine dendrimer is 1: (1.2-6), the reaction temperature is 50-70 ℃, and the reaction time is 12-24 hours; the molar ratio of the triethoxysilyl sulfur-containing polyamide-amine dendrimer to the tetraethoxysilane, the water and the ammonium fluoride is 1: (2-10): (1-12): (0.01-0.05), the reaction temperature is 25 ℃, and the reaction time is 24-36 hours.