CN112657469B

CN112657469B - Preparation method of amino-functionalized silsesquioxane-based heavy metal ion adsorbent

Info

Publication number: CN112657469B
Application number: CN202011395226.8A
Authority: CN
Inventors: 刘鸿志; 葛倩
Original assignee: Shandong University
Current assignee: Shandong University
Priority date: 2020-12-03
Filing date: 2020-12-03
Publication date: 2022-09-23
Anticipated expiration: 2040-12-03
Also published as: CN112657469A

Abstract

The invention provides a preparation method of a heavy metal ion adsorbent based on amino functionalized silsesquioxane; the preparation method comprises the following steps: dissolving octachloropropyl silsesquioxane with a cage-type structure and triaminoethylamine in an organic solvent, adding an acid acceptor, uniformly mixing, and carrying out heating reaction; after the reaction is finished, cooling to room temperature, filtering and washing to obtain a solid; the acid-absorbing agent is triethylamine or sodium bicarbonate; and performing Soxhlet extraction on the obtained solid, and drying to obtain the product. The invention takes triethylamine or sodium bicarbonate as an acid absorbent, and prepares two hybrid network functional material adsorbents with different structures through nucleophilic substitution reaction; the prepared adsorbent has good chemical stability and thermal stability, greatly improves the adsorption capacity of the silsesquioxane-based hybrid material on heavy metal ions in wastewater, and has great potential application value in the adsorption field.

Description

Preparation method of amino-functionalized silsesquioxane-based heavy metal ion adsorbent

Technical Field

The invention relates to a preparation method of a heavy metal ion adsorbent based on amino functionalized silsesquioxane, belonging to the technical field of environmental protection and chemical separation.

Background

With the rapid development of the world economy, the machine manufacturing industry is growing rapidly, but the environmental problems caused by the rapid development are becoming more serious. The harm caused by the problem of water resource pollution is gradually intensified, and sudden heavy metal pollution is particularly serious in a plurality of pollutants. The heavy metal has the degradability, and the harmfulness of the heavy metal is difficult to reduce only by the physical, chemical or microbial purification action of the water body, so that the heavy metal pollution in the water body is difficult to disappear after sudden heavy metal pollution accidents occur. For example, mercury has a very strong bioaccumulation capacity, can enter and stay in the human body through the food chain, and causes irreversible damage to the human nervous system. Silver, as a noble metal, plays an important role in many areas of the contemporary industry; however, the natural resources of silver are very limited, and the current global silver mineral resources are gradually depleted; and silver ions are toxic and can accumulate in the human body to cause harm. Copper is a trace element required by human bodies, deficiency diseases can be caused when the intake of copper in the human bodies is insufficient, and poisoning can be caused when the intake of copper is excessive, wherein the poisoning comprises acute copper poisoning, hepatolenticular degeneration, intrahepatic cholestasis of children and the like. Therefore, advanced technologies are continuously developed to remedy the past pollution and prevent further discharge of these metal ions, mainly including methods of sedimentation filtration, ion exchange, reverse osmosis, membrane separation, electrochemical reduction, and the like. However, most of the methods are not widely used due to high operation costs and low feasibility of industrialization. In contrast, adsorption technology has the advantages of low cost, simple design, easy operation, and the like, and is the most common and promising method so far.

In recent years, organosilicon materials have attracted much attention as important fields of material science due to their excellent properties, and have been widely used in the fields of catalysis, adsorption, separation, gas storage, and the like. Among the many raw materials for hybrid material synthesis, silsesquioxane is considered as an ideal building block of hybrid materials due to a special molecular-scale organic-inorganic hybrid structure. The silsesquioxane has the composition of [ RSiO _1.5 ] _n (R is an organic group, and is most typical when n is 8), the hybrid polymer takes an inorganic Si-O-Si structure as an inner core, and the periphery of the hybrid polymer is connected with a modified organic group, so that an excellent platform is provided for preparing a novel hybrid material with excellent thermal property and mechanical property, and the hybrid polymer becomes an ideal building unit for building a hybrid polymer; especially, the organic part can generate new synergistic performance while ensuring good solubility, which is very important in practical application. Among Silsesquioxane compounds with different structures, Silsesquioxane (POSS for short) with a Cage-type structure and materials thereof are widely researched, and related properties and potential applications thereof are also explored in detail; the organic-inorganic hybrid porous material constructed by the porous material has higher specific surface area and can achieve extremely high adsorption capacity to dye; the fluorescent group is introduced, so that the fluorescent probe can be used for detecting metal ions and nitroaromatic compounds, and has high sensitivity; the grafting of the modified starch onto the fabric can enable the fabric to have super hydrophobicity, chemical stability and antifouling performance.

However, the study of network functional materials based on silsesquioxane having a cage structure is still insufficient, and the adsorption amount of heavy metal ions is not high; the network functional material obtained by hydrophilic modification of the cage-type silsesquioxane is expected to show some more superior performances, so the research is necessary.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a preparation method of a heavy metal ion adsorbent based on amino functionalized silsesquioxane. The invention takes triethylamine or sodium bicarbonate as an acid absorbent, and prepares two hybrid network functional material adsorbents with different structures through nucleophilic substitution reaction; the prepared hybrid network functional material adsorbent has good chemical stability and thermal stability, greatly improves the adsorption capacity of the silsesquioxane-based hybrid material on heavy metal ions in wastewater, and has great potential application value in the adsorption field.

The technical scheme of the invention is as follows:

a preparation method of a heavy metal ion adsorbent based on amino functionalized silsesquioxane comprises the following steps:

(1) dissolving octachloropropyl silsesquioxane with a cage-type structure and triaminoethylamine in an organic solvent, adding an acid acceptor, uniformly mixing, and carrying out heating reaction; after the reaction is finished, cooling to room temperature, filtering and washing to obtain a solid; the acid-absorbing agent is triethylamine or sodium bicarbonate;

(2) and (2) soxhlet extraction is carried out on the solid obtained in the step (1), and the obtained solid is dried to obtain the amino-functionalized silsesquioxane-based heavy metal ion adsorbent.

According to the present invention, the chloropropylsilsesquioxane of cage structure described in step (1) is commercially available or prepared according to the prior art.

According to the invention, preferably, the mol ratio of the chloropropyl silsesquioxane with the cage structure in the step (1) to the triaminoethylamine is 1 (2-5); preferably 1 (2.5-4).

According to the present invention, it is preferable that the organic solvent described in the step (1) is N, N-dimethylformamide, dichloromethane, chloroform or tetrahydrofuran; n, N-dimethylformamide is preferred.

According to the invention, the ratio of the mass of the chloropropyl silsesquioxane with a cage structure in the step (1) to the volume of the organic solvent is preferably 1 (15-50) g/mL, and preferably 1 (15-30) g/mL.

According to the present invention, it is preferred that the mass of the acid scavenger in step (1) is 1 to 17 times the mass of the triaminoethylamine; preferably, the mass of the acid acceptor is 3 to 16 times of that of the triaminoethylamine.

According to the invention, the heating reaction temperature in the step (1) is preferably 100-110 ℃; preferably, the heating reaction temperature is 110 ℃. The heating reaction time is 12-48 h, preferably 24 h.

According to the present invention, it is preferable that the heating reaction in step (1) is performed under an inert gas atmosphere.

Preferably, the inert gas is nitrogen or argon.

According to the present invention, it is preferable that the washing step in the step (1) is: the solid obtained after filtration is washed respectively 3 times by acetone, water, absolute ethyl alcohol and dichloromethane in sequence, and then subjected to Soxhlet extraction.

According to the present invention, preferably, the soxhlet extraction step in step (2) is: soxhlet extracting the solid obtained in the step (1) in methanol or dichloromethane for 60-80 h. The effect of the Soxhlet extraction of the invention is to remove impurities in the solid, mainly unreacted monomers and acid scavengers.

According to the invention, preferably, the drying in the step (2) is vacuum drying, and the temperature of the vacuum drying is 60-100 ℃, preferably 70-80 ℃; the vacuum drying time is 12-48 h, preferably 20-24 h.

The invention has the following technical characteristics and beneficial effects:

1. the preparation steps of the hybrid polymer are simple, the preparation process conditions are easy to control, no expensive catalyst is needed, the used raw materials are easy to obtain, and the yield of the target product is high. The invention adopts specific raw materials, namely octachloropropyl silsesquioxane with a cage-shaped structure and triaminoethylamine as construction units, and prepares the hybrid network functional material with a certain crosslinking degree and polymerization degree by nucleophilic substitution reaction of chlorine in the chloropropyl silsesquioxane and ammonia in the triaminoethylamine.

2. The polymer obtained by the invention is an organic-inorganic hybrid material, and because the structure of the construction unit is special, the obtained polymer forms completely different surface structures due to the difference of the acid-absorbing agent. The acid-absorbing agent used in the invention is sodium bicarbonate or triethylamine, and the acid-absorbing agent is added to absorb HCl generated by nucleophilic substitution, so that a cross-linked network is successfully constructed. When the acid acceptor is sodium bicarbonate, the acid acceptor is sodium bicarbonate hydrolyzed in water to generate OH ^- ，OH ^- Attacking a silsesquioxane cage structure to break partial silica bonds to generate silicon hydroxyl groups to obtain a hybrid cross-linked network with a PAC-2 structure; furthermore, when these cages are connected together by rigid connecting elements, this partial cage structure failure is believed to be to relieve structural stresses in the network. When the acid-absorbing agent is triethylamine, a hybrid cross-linked network with a PAC-1 structure with a complete silsesquioxane structure can be obtained.

3. The amino-functionalized silsesquioxane-based heavy metal ion adsorbent disclosed by the invention has good chemical stability and thermal stability. The chloropropyl group on each vertex of the cage-type chloropropyl silsesquioxane provides 8 reaction sites; although the reaction sites can not be completely reacted due to steric hindrance and the like, a plurality of reaction sites are beneficial to forming a highly cross-linked reticular hybrid network functional material; according to soft and hard acid-base theory, functional groups containing nitrogen easily coordinate with metal ions, and triaminoethylamine is rich in N atoms, has good hydrophilicity and is easy to coordinate with the metal ions, so that the metal ions are adsorbed. Meanwhile, the Si-O-Si core of the silsesquioxane is rich in O atoms and is an electronegative unit, so that the hybrid material obtained by the invention is more prone to adsorbing heavy metal ion substances. Therefore, the hybrid network functional material with the specific structure has great potential application value in the field of adsorption.

Drawings

FIG. 1 shows the adsorbent prepared in examples 1 and 2 and octachloropropylsilsesquioxane (POSS-Cl) having a cage structure ₈ ) An infrared spectrum of (1).

FIG. 2 shows the solid carbon spectrum and cage structure of the adsorbents prepared in examples 1 and 2Octachloropropylsilsesquioxane (POSS-Cl) ₈ ) Liquid carbon spectrum.

FIG. 3 shows the solid silicon spectrum and cage-type octachloropropylsilsesquioxane (POSS-Cl) of the adsorbents prepared in examples 1 and 2 ₈ ) Liquid silicon spectrum.

FIG. 4 is a thermogravimetric analysis plot of the adsorbents prepared in examples 1 and 2.

FIG. 5 is a scanning electron micrograph of the adsorbents prepared in examples 1 and 2.

Fig. 6 is a graph of the adsorption amount of the adsorbent prepared in example 1 to copper, silver and mercury ion aqueous solutions with different concentrations.

Fig. 7 is a graph of the adsorption amount of the adsorbent prepared in example 2 to copper, silver and mercury ion aqueous solutions with different concentrations.

FIG. 8 is adsorbent pair Hg prepared in example 2 ²⁺ The cyclic stability plot of efficiency is removed.

FIG. 9 is a schematic diagram of the reaction scheme of the present invention.

Detailed Description

The invention will be further illustrated by the following examples in connection with the accompanying drawings without limiting the scope of the invention thereto.

The raw materials used in the examples were commercially available unless otherwise specified; the method is conventional unless otherwise specified, and the equipment is conventional unless otherwise specified.

The chloropropyl silsesquioxane with a cage structure used in the examples can be prepared by reference to the literature of Organometallics 2008,27, 793-:

(1) adding 300mL of methanol, 60mL of chloropropyltrimethoxysilane and 10mL of water into a flask, uniformly stirring, slowly adding 30mL of hydrochloric acid with the mass concentration of 36-38% at 0 ℃, stirring for 2-3 min after dropwise addition is finished, raising the temperature to room temperature after the system is stable, and stirring for 5 days at room temperature.

(2) And after the reaction is finished, carrying out suction filtration, washing the obtained solid with methanol to obtain an oil-free substance, and carrying out vacuum drying to obtain a white powder solid, namely the chloropropyl silsesquioxane with the cage structure.

The synthetic route is as follows:

example 1

A preparation method of a heavy metal ion adsorbent (with a structure shown as PAC-1) based on amino functionalized silsesquioxane comprises the following steps:

0.73g (0.7mmol) octachloropropylsilsesquioxane of cage structure and 0.32g (2mmol) triaminoethylamine are charged into a dry three-neck flask with a condenser and a magnetic stirrer, the flask is evacuated and filled with nitrogen, then 15mL N, N-Dimethylformamide (DMF) are added, the mixture is stirred at room temperature for 2 hours until the mixture is completely dissolved, 7mL triethylamine is added, stirring is continued for 3 hours, the mixture is uniformly mixed, and the temperature is raised to 110 ℃. The reaction was stirred at 110 ℃ for 24 hours. After the reaction, the mixture is cooled to room temperature, solid polymer is obtained by filtration, the solid polymer is washed by acetone, water, absolute ethyl alcohol and dichloromethane for 3 times in sequence, then, soxhlet extraction is carried out by ethanol for 72 hours, and vacuum drying is carried out for 24 hours at 70 ℃ to obtain 0.95g of brown yellow powdery solid (yield: 90 percent), which is called PAC-1 for short.

The adsorbent prepared in this example and octachloropropylsilsesquioxane (POSS-Cl) having a cage structure ₈ ) The infrared spectra of (A) are shown in FIG. 1 at 1100 and 470cm ^-1 The characteristic peaks are respectively a stretching vibration peak and a bending vibration peak of Si-O-Si; 1650cm in the Infrared Spectrum of PAC-1 ^-1 The bending vibration peak at N-H appeared at the same time of 3300cm ^-1 The new characteristic peak represents the stretching vibration peak of the amino group, and proves that the triaminoethylamine and the octachloropropyl silsesquioxane with a cage structure successfully react.

The solid carbon spectrum of the adsorbent prepared in the example is shown in FIG. 2, and the characteristic peaks of 9.3, 26.3 and 47.1ppm are respectively attributed to three saturated alkyl carbons Si-CH of octachloropropyl silsesquioxane with cage structure ₂ 、-CH ₂ -、-CH ₂ And (4) Cl. However, the peak width was significantly increased, and a distinct multimodal structure appeared at 47.3ppm, indicating that saturation with different amino groups occurredAnd carbon, confirming the formation of a crosslinked network, PAC-1 was successfully prepared.

The solid silicon spectrum of the adsorbent prepared in this example is shown in fig. 3, and it can be seen from the figure that the characteristic peak (67.15ppm) in PAC-1 exists and is a single strong peak, which indicates that the cage structure of octachloropropylsilsesquioxane is basically kept intact, no collapse phenomenon occurs, and the cross-linked network structure is constructed during the preparation process.

The thermogravimetric analysis curve of the adsorbent prepared in this example is shown in fig. 4, and it can be seen from the graph that PAC-1 loses 5% weight at 235 ℃, and has better thermal stability.

As shown in fig. 5, the scanning electron microscope image of the adsorbent prepared in this example shows that PAC-1 has a smooth and regular particle structure with a surface morphology, and the particle size of the PAC-1 is several micrometers to several tens of micrometers.

The PAC-1 adsorbent prepared in this example was subjected to elemental analysis, and the results were as follows: the content of nitrogen element was 9.85 wt%, the content of carbon element was 31.61 wt%, and the content of hydrogen element was 7.588 wt%.

Example 2

A preparation method of a heavy metal ion adsorbent (with a structure shown as PAC-2) based on amino functionalized silsesquioxane comprises the following steps:

0.73g (0.7mmol) octachloropropylsilsesquioxane of cage structure and 0.32g (2mmol) triaminoethylamine are charged into a dry three-necked flask with a condenser and magnetic stirrer, the flask is evacuated and filled with nitrogen, then 15mL of N, N-Dimethylformamide (DMF) are added, the mixture is stirred at room temperature for 2 hours until it is completely dissolved, 1.07g of sodium bicarbonate is added, stirring is continued for 3 hours and the mixture is mixed uniformly and then heated to 110 ℃. The reaction was stirred at 110 ℃ for 24 hours. After the reaction is finished, the reaction product is cooled to room temperature, solid polymer is obtained through filtration, the solid polymer is washed for 3 times by acetone, water, absolute ethyl alcohol and dichloromethane in sequence, then soxhlet extraction is carried out for 72 hours by ethanol, and vacuum drying is carried out for 24 hours at 70 ℃ to obtain 0.87g of light yellow powdery solid (yield: 83 percent), which is called PAC-2 for short.

The adsorbent prepared in this example and octachloropropyl of cage structureSilsesquioxane (POSS-Cl) ₈ ) The infrared spectra of (A) are shown in FIG. 1 at 1100 and 470cm ^-1 The characteristic peaks are respectively a stretching vibration peak and a bending vibration peak of Si-O-Si; 1650cm in the Infrared Spectrum of PAC-2 ^-1 The bending vibration peak at N-H appeared at the same time of 3300cm ^-1 The new characteristic peak represents the stretching vibration peak of amino, which proves the successful reaction of triaminoethylamine and octachloropropyl silsesquioxane with cage structure.

The solid carbon spectrum of the adsorbent prepared in the example is shown in FIG. 2, and the characteristic peaks of 9.3, 26.3 and 47.1ppm are respectively attributed to three saturated alkyl carbons Si-CH of octachloropropyl silsesquioxane with cage structure ₂ 、-CH ₂ -、-CH ₂ And (4) Cl. However, the width of the peak was significantly increased, while 47.3ppm showed a distinct multimodal structure, indicating the presence of saturated carbons attached to different amino groups, demonstrating the formation of a crosslinked network and the successful preparation of PAC-2.

The solid silicon spectrum of the adsorbent prepared in this example is shown in FIG. 3, from which it can be seen that the PAC-2 characteristic peak has a significantly increased width and side peaks, combined with an infrared spectrum of 1100cm ^-1 The bimodal structure of (b) can confirm that when a network structure is formed, a part of the cage structure is destroyed due to the introduction of sodium bicarbonate.

The thermogravimetric analysis curve of the adsorbent prepared in the example is shown in fig. 4, and it can be seen from the graph that the PAC-2 has 5% weight loss at 325 ℃, and has better heat resistance compared with PAC-1 and PAC-2, mainly because the PAC-2 has a more complete cross-linked network structure although a part of cage structure is damaged.

As shown in fig. 5, a scanning electron microscope image of the adsorbent prepared in this example shows that PAC-2 is a relatively regular cluster structure with a wide size distribution from 100 nm to several tens of microns; and PAC-2 forms a rougher surface due to collapsed framework coalescence of the silsesquioxane cage.

The elemental analysis of the adsorbent PAC-2 prepared in this example was conducted as follows: the content of nitrogen element was 10.51 wt%, the content of carbon element was 37.5 wt%, and the content of hydrogen element was 7.379 wt%. It can be seen that the nitrogen content in PAC-2 is higher than that in PAC-1, because the cage structure of silsesquioxane is partially destroyed, the steric hindrance is smaller, and more amino groups and chloropropyl groups are subjected to nucleophilic substitution.

Example 3

0.73g (0.7mmol) octachloropropylsilsesquioxane of cage structure and 0.32g (2mmol) triaminoethylamine are charged into a dry three-neck flask with a condenser and a magnetic stirrer, the flask is evacuated and filled with nitrogen, then 20mL N, N-Dimethylformamide (DMF) are added, the mixture is stirred at room temperature for 2 hours until complete dissolution, 2mL triethylamine is added, stirring is continued for 3 hours, the mixture is uniformly mixed, and the temperature is raised to 110 ℃. The reaction was stirred at 110 ℃ for 24 hours. Cooling to room temperature after the reaction is finished, filtering to obtain a solid polymer, washing the solid polymer for 3 times by sequentially using acetone, water, absolute ethyl alcohol and dichloromethane, then performing Soxhlet extraction by using ethanol for 72 hours, and performing vacuum drying at 70 ℃ for 24 hours to obtain the product.

Example 4

0.73g (0.7mmol) octachloropropylsilsesquioxane of cage structure and 0.32g (2mmol) triaminoethylamine are charged into a dry three-neck flask with a condenser and a magnetic stirrer, the flask is evacuated and filled with nitrogen, then 20mL N, N-Dimethylformamide (DMF) are added, the mixture is stirred at room temperature for 2 hours until complete dissolution, 3.5mL triethylamine are added, stirring is continued for 3 hours, the mixture is uniformly mixed, and the temperature is raised to 110 ℃. The reaction was stirred at 110 ℃ for 24 hours. Cooling to room temperature after the reaction is finished, filtering to obtain a solid polymer, washing the solid polymer for 3 times by sequentially using acetone, water, absolute ethyl alcohol and dichloromethane, then performing Soxhlet extraction by using ethanol for 72 hours, and performing vacuum drying at 70 ℃ for 24 hours to obtain the product.

Example 5

0.73g (0.7mmol) octachloropropylsilsesquioxane of cage structure and 0.32g (2mmol) triaminoethylamine are charged into a dry three-necked flask with a condenser and magnetic stirrer, the flask is evacuated and filled with nitrogen, then 20mL N, N-Dimethylformamide (DMF) are added, the mixture is stirred at room temperature for 2 hours until complete dissolution, 0.5g sodium bicarbonate is added, stirring is continued for 3 hours and the mixture is mixed uniformly and then heated to 110 ℃. The reaction was stirred at 110 ℃ for 24 hours. Cooling to room temperature after the reaction is finished, filtering to obtain a solid polymer, washing the solid polymer for 3 times by sequentially using acetone, water, absolute ethyl alcohol and dichloromethane, then performing Soxhlet extraction by using ethanol for 72 hours, and performing vacuum drying at 70 ℃ for 24 hours to obtain the product.

Comparative example 1

A method of making an adsorbent, as described in example 2, except that: the reaction temperature is 90 ℃; other conditions and procedures were consistent with example 2. The yield of the resulting adsorbent was 57%. Compared with the example 2 of the invention, the reaction temperature is too low, which is not favorable for the full reaction, and the yield of the target product is low.

Comparative example 2

A method of making an adsorbent, as described in example 2, except that: the reaction temperature is 120 ℃; other conditions and procedures were consistent with example 2. The yield of the resulting adsorbent was 92%.

Test example 1

Heavy metal ion adsorption test:

the adsorbents prepared in examples 1 and 2 were investigated for adsorption of heavy metal ions.

Test samples: adsorbents prepared in examples 1 and 2.

Preparing a heavy metal ion solution: preparing Cu ²⁺ The concentration is 10-300mgL ^-1 Cu of (2) ²⁺ (anion is NO) ₃ ^- ) Aqueous solution of Ag ⁺ The concentration is 7-300mgL ^-1 Ag of (A) ⁺ (anion is NO) ₃ ^- ) An aqueous solution, and Hg ²⁺ The concentration is 30-250mg L ^-1 Hg of ²⁺ (anion is Cl) ^- ) An aqueous solution.

The test method comprises the following steps: a50 mL sample bottle was charged with 3mg of the test sample, 30mL of the prepared heavy metal ion solution was added, and the mixture was stirred at room temperature for 16 hours. The concentration of the metal ion solution before and after adsorption is measured by a flame atomic absorption spectrometer, and the adsorption quantity of the adsorbent of the invention to the metal ions is calculated.

FIG. 6 shows the PAC-1 adsorbent obtained in example 1 for different concentrations of Cu ²⁺ Aqueous solution, Ag ⁺ Aqueous solution and Hg ²⁺ Adsorption capacity curve of aqueous solution. As can be seen from the figure, the adsorbent PAC-1 obtained by the invention is relative to Cu ²⁺ 、Ag ⁺ And Hg ²⁺ The adsorption capacity of the adsorbent can reach 77.8 mg g, 358.1 mg and 404.1mg g respectively ^-1 。

FIG. 7 shows the PAC-2 adsorbent obtained in example 2 for different concentrations of Cu ²⁺ Aqueous solution, Ag ⁺ Aqueous solution and Hg ²⁺ Adsorption capacity curve of aqueous solution. As can be seen from the figure, PAC-2 obtained by the present invention is aligned with Cu ²⁺ 、Ag ⁺ And Hg ²⁺ The adsorption capacity can reach 119.6, 180.0 and 735.0mg g ^-1 。

And (3) analysis: the hybrid network functional material is rich in N atoms and shows electronegativity, so that the hybrid network functional material has larger adsorption capacity on metal ions. For Hg due to coordination and electrostatic interaction ²⁺ The adsorption amount of (2) is larger.

In addition, the adsorbent obtained in comparative example 2 was used for Hg ²⁺ Has a maximum adsorption amount of 426mgg ^-1 As can be seen from comparison with example 2 of the present invention, the adsorbent prepared by the present invention has a more excellent adsorption effect, which indicates that the reaction temperature has an important influence on the adsorption effect of the adsorbent.

Test example 2

And (3) testing the cycle performance:

the cycle performance of the adsorbent prepared in example 2 for heavy metal ion adsorption was investigated.

Test samples: the adsorbent prepared in example 2.

Preparing a heavy metal ion solution: preparation of Hg ²⁺ The concentration is 50mg L ^-1 Hg of ²⁺ (anion is Cl) ^- ) An aqueous solution.

The test method comprises the following steps:

adding 3mg of a test sample into a 50mL sample bottle, adding 30mL of the prepared heavy metal ion solution, and stirring at room temperature for 16 hours; the concentration of the metal ion solution before and after adsorption is measured by a flame atomic absorption spectrometer, and the removal rate of the adsorbent of the invention to the metal ions is calculated. Then filtering to obtain an adsorbent, eluting metal ions by using 1mol/L HCl, and repeatedly using the metal ions for the next adsorption after washing. The adsorption results after repeating the adsorption of the metal ions 5 times as described above are shown in FIG. 8.

FIG. 8 shows the adsorbent PAC-2 vs Hg obtained in example 2 ²⁺ A cyclic stability plot of efficiency is removed. As can be seen, the Hg content was measured after five cycles ²⁺ The removal efficiency of (2) still can reach more than 99 percent, and the results show that the PAC-2 has excellent regeneration stability.

Claims

1. A preparation method of a heavy metal ion adsorbent based on amino functionalized silsesquioxane comprises the following steps:

(1) dissolving octachloropropyl silsesquioxane with a cage-type structure and triaminoethylamine in an organic solvent, adding an acid acceptor, uniformly mixing, and carrying out heating reaction; after the reaction is finished, cooling to room temperature, filtering and washing to obtain a solid; the acid-absorbing agent is triethylamine or sodium bicarbonate; the heating reaction temperature is 100-110 ℃;

2. The preparation method of the amino functionalized silsesquioxane-based heavy metal ion adsorbent according to claim 1, wherein the molar ratio of octachloropropyl silsesquioxane with a cage-type structure to triaminoethylamine in the step (1) is 1 (2-5).

3. The preparation method of the amino functionalized silsesquioxane-based heavy metal ion adsorbent according to claim 2, wherein the molar ratio of octachloropropyl silsesquioxane with a cage-type structure to triaminoethylamine in the step (1) is 1 (2.5-4).

4. The method for preparing the amino functionalized silsesquioxane-based heavy metal ion adsorbent according to claim 1, wherein the organic solvent in the step (1) is N, N-dimethylformamide, dichloromethane, chloroform or tetrahydrofuran.

5. The preparation method of the amino-functionalized silsesquioxane-based heavy metal ion adsorbent according to claim 1, wherein the volume ratio of the octachloropropyl silsesquioxane with the cage-type structure in the step (1) to the organic solvent is 1 (15-50) g/mL.

6. The preparation method of the amino-functionalized silsesquioxane-based heavy metal ion adsorbent according to claim 5, wherein the volume ratio of the octachloropropyl silsesquioxane with the cage-type structure in the step (1) to the organic solvent is 1 (15-30) g/mL.

7. The method for preparing the amino functionalized silsesquioxane based heavy metal ion adsorbent according to claim 1, wherein the mass of the acid scavenger in the step (1) is 1-17 times that of triaminoethylamine.

8. The method for preparing the amino functionalized silsesquioxane based heavy metal ion adsorbent according to claim 7, wherein the mass of the acid scavenger in the step (1) is 3-16 times that of triaminoethylamine.

9. The preparation method of the amino functionalized silsesquioxane-based heavy metal ion adsorbent according to claim 1, wherein the heating reaction temperature in the step (1) is 110 ℃; the heating reaction time is 12-48 h.

10. The method for preparing the amino functionalized silsesquioxane-based heavy metal ion adsorbent according to claim 1, wherein the heating reaction in step (1) is performed under the protection of an inert gas.

11. The method for preparing the amino functionalized silsesquioxane-based heavy metal ion adsorbent according to claim 10, wherein the inert gas is nitrogen or argon.

12. The method for preparing the amino functionalized silsesquioxane based heavy metal ion adsorbent according to claim 1, wherein the washing step in the step (1) is: the solid obtained after filtration is washed respectively 3 times by acetone, water, absolute ethyl alcohol and dichloromethane in sequence, and then subjected to Soxhlet extraction.

13. The method for preparing the amino functionalized silsesquioxane-based heavy metal ion adsorbent according to claim 1, wherein the Soxhlet extraction step in the step (2) is as follows: soxhlet extracting the solid obtained in the step (1) in methanol or dichloromethane for 60-80 h.

14. The preparation method of the amino functionalized silsesquioxane-based heavy metal ion adsorbent according to claim 1, wherein the drying in the step (2) is vacuum drying, and the temperature of the vacuum drying is 60-100 ℃; the vacuum drying time is 12-48 h.