A composite adsorption material for efficiently purifying Hg (II), preparation method and application thereof

Abstract

The present invention relates to a composite adsorption material for efficiently purifying Hg(II), a preparation method, and applications thereof. 3-Aminopropyltrimethoxysilane (APTMS) is immobilized on the surface of DMSN to introduce amino groups. A silanization product is obtained by centrifugation, which is then dispersed in xylene with thioglycolic acid. The composite adsorption material TGC@DMSN is washed and dried. At a pH of 8, the composite adsorption material exhibits excellent removal of trace Hg(II) in water, with a maximum adsorption capacity of 257.1 mg / g. The composite adsorption material also exhibits good recycling performance and has promising application prospects in the field of environmental water purification.

Description

Technical Field

[0001] The present invention relates to the field of Hg(II) adsorption materials, and in particular to a composite adsorption material for efficiently purifying Hg(II), a preparation method and application thereof. Background Art

[0002] With the acceleration of the industrialization process of human society, wastewater containing heavy metals is discharged into the environment in large quantities. These heavy metals are non-biodegradable and accumulate in the food chain. Even at extremely low concentrations, they can pose a serious threat to the ecosystem and public health. Therefore, heavy metal pollution is considered a key issue for human life and health and environmental safety. Among these heavy metals, mercury is considered to be one of the most toxic metals found in the environment. Excessive exposure to mercury (Hg) compounds can cause serious damage to cardiovascular, blood, lung and kidney functions. Removing mercury from the water environment is an issue that urgently needs to be addressed in human development. Common methods for treating mercury-containing wastewater include chemical precipitation, adsorption, ion exchange, electrochemical treatment and membrane filtration. Among them, adsorption has become a commonly used method for purifying mercury-containing wastewater due to its simple operation, high purification efficiency and economic benefits.

[0003] Compared to conventional adsorption materials, micro-nanomaterials and mesoporous nanomaterials possess higher specific surface areas and porosities, providing more sites for functionalization and mercury (Hg) adsorption, making them the preferred carriers for mercury wastewater removal. Mesoporous nanomaterials (MSNs) have been widely used in drug delivery, biosensors, imaging, catalysis, water treatment, and other related fields due to their ordered mesopores, large specific surface area, rigidity, and ease of surface modification.

[0004] Therefore, it is of great significance to develop a composite Hg(II) adsorption material based on mesoporous nanomaterials for the removal of mercury (Hg) from wastewater. Summary of the Invention

[0005] The present invention aims to provide a composite adsorption material for efficiently purifying Hg(II). The material comprises amino groups introduced onto the surface of dendritic mesoporous SiO2 by silanization, followed by grafting of thioglycolic acid onto the silanized dendritic mesoporous SiO2 via an amidation reaction, ultimately yielding the composite Hg(II) adsorption material TGC@DMSN. The composite adsorption material TGC@DMSN can effectively remove Hg(II) from water, exhibits good recyclability, and has promising application prospects in the field of environmental water purification.

[0006] Another object of the present invention is to provide a method for preparing a composite adsorbent material for efficiently purifying Hg(II). This method has the advantages of simple steps, convenience, and rapidity. The resulting composite adsorbent material, TGC@DMSN, can be used for the effective purification of Hg(II) and has broad application prospects in the purification of Hg(II)-containing wastewater. This object is achieved through the following technical solutions:

[0007] A method for preparing a composite adsorption material for efficiently purifying Hg(II) comprises the following steps:

[0008] S1. Disperse DMSN in toluene, add APTMS, and reflux the mixture at 130-140°C for 20-24 hours. Centrifuge to obtain the silylated product APTMS@DMSN.

[0009] S2, taking the silylation product APTMS@DMSN obtained in step S1 and thioglycolic acid, dispersing them in xylene, heating them under reflux at 110-120° C. for 20-24 hours, washing and drying them to obtain the composite adsorption material TGC@DMSN;

[0010] Furthermore, the mass-to-volume ratio of DMSN to APTMS in step S1 is 1:1 (g:mL).

[0011] Furthermore, the mass-to-volume ratio of DMSN to toluene in step S1 is 1:200 (g:mL).

[0012] Furthermore, the mass-to-volume ratio of the silylation product to thioglycolic acid in step S2 is 1:1 (g:mL).

[0013] Furthermore, the mass-to-volume ratio of the silylation product to xylene in step S2 is 1:30 (g:mL).

[0014] Furthermore, the DMSN described in step S2 is prepared using CTAB and urea as templates and TEOS as a silicon source.

[0015] Furthermore, the preparation method of DMSN described in step S2 is as follows: 1.0 g of CTAB and 0.6 g of urea are dissolved in 30.0 mL of distilled water, 30.0 mL of cyclohexane and 1.5 mL of n-pentanol are added and stirred to form a microemulsion, 10.0 mL of TEOS is added and stirred at 330-350 rpm for 2.5-3 h, the mixture is transferred to a reactor with a magnetic stirrer, and stirring is continued at 110-120 ° C for 3.5-4 h. Finally, the product is calcined at 540-550 ° C for 5-6 h to obtain DMSN.

[0016] Another object of the present invention is to provide an application of the composite adsorption material for efficiently purifying Hg(II) in the adsorption of Hg(II), wherein the optimal conditions are immersion of TGC@DMSN for 20 minutes at pH = 8 and an initial Hg(II) concentration of 100 ppm.

[0017] The composite adsorption material TGC@DMSN provided by the present invention can remove 97.5% of Hg(II) within 20 minutes.

[0018] The present invention designs and prepares a novel composite adsorbent material, TGC@DMSN, which effectively removes mercury (Hg) from water through chemical adsorption, leveraging surface thiol groups. The strong binding of surface thiol groups to Hg allows for efficient adsorption of Hg in water within a relatively short time. The mercury can then be recovered through simple washing with hydrochloric acid for recycling, preventing secondary pollution. Therefore, the composite adsorbent material TGC@DMSN prepared in this invention has broad application prospects in the removal of mercury (Hg) from environmental water. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a rendering of the SEM and TE micromorphology observation of the composite adsorption material TGC@DMSN prepared by the present invention;

[0020] Figure 2 Graph showing the effect of pH on the adsorption of Hg(II) by the raw material DMSN and the composite adsorption material TGC@DMSN prepared in the present invention;

[0021] Figure 3 Graph showing the effect of initial Hg(II) concentration on the Hg(II) adsorption by the raw material DMSN and the composite adsorption material TGC@DMSN prepared in the present invention;

[0022] Figure 4 This is a graph showing the recycling results of Hg(II) adsorption by the composite adsorption material TGC@DMSN prepared by the present invention;

[0023] Figure 5 Graph showing the effects of ambient temperature and contact time on the adsorption of Hg(II) by the composite adsorption material TGC@DMSN prepared in the present invention;

[0024] Figure 6 This is the N2 adsorption-desorption curve effect diagram of dendritic mesoporous silica (DMSN) and thioglycolic acid functionalized dendritic mesoporous silica composite material (TGA@DMSN);

[0025] Table 1 shows the specific surface area and pore volume analysis of dendritic mesoporous silica (DMSN) and thioglycolic acid functionalized dendritic mesoporous silica composite material (TGA@DMSN). DETAILED DESCRIPTION

[0026] To better understand the technical solutions of the present invention, the present invention includes but is not limited to the specific embodiments described below. Similar technologies and methods should be considered within the scope of protection of the present invention. To further clarify the technical problems, technical solutions, and advantages to be solved by the present invention, the following detailed description is provided in conjunction with the accompanying drawings and specific embodiments.

[0027] It should be understood that the embodiments described herein are only a portion of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] The terms used in the examples of this invention are for the purpose of describing specific embodiments only and are not intended to limit the invention. All materials referred to in the examples and appended claims unless otherwise indicated are commercially available products. Dendritic mesoporous SiO2 (DMSN), 3-aminopropyltrimethoxysilane (APTMS), cetyltrimethylammonium bromide (CTAB), tetraethyl orthosilicate (TEOS), and thioglycolic acid (TGA) are used in this invention.

[0029] Preparation Example 1. Preparation of composite adsorption material TGC@DMSN.

[0030] Weigh 1.0g CTAB and 0.6g urea and dissolve them in 30.0mL distilled water. Quickly add 30.0mL cyclohexane and 1.5mL n-pentanol and stir to form a microemulsion. Then add 10.0mL TEOS and stir at 330-350 rpm at room temperature for 2.5-3h. Then continue stirring the mixture at 110-120℃ for 3.5-4h. After filtering, washing and drying, calcinate at 550℃ for 5-6h to obtain DMSN. Take 0.1g DMSN and 0.1mL ATPMS and disperse them in 30.0mL toluene. Heat and reflux at 130-140℃ for 20-24h. Then disperse 1.0g product and 1mL thioglycolic acid in 30mL xylene and reflux at 110-120℃ for 20-24h to obtain the composite adsorbent material TGC@DMSN. Its scanning electron microscope and transmission electron microscope morphology are as follows: Figure 1 shown.

[0031] Preparation Example 2: This example differs from Preparation Example 1 in that

[0032] The mass-to-volume ratio of DMSN to APTMS is 1:2 (g:mL);

[0033] Preparation Example 3: This example differs from Preparation Example 1 in that

[0034] The mass-to-volume ratio of DMSN to APTMS is 1:0.5 (g:mL);

[0035] Preparation Example 4: This example differs from Preparation Example 1 in that

[0036] The mass-to-volume ratio of DMSN to APTMS is 1:3 (g:mL);

[0037] The results show that the more APTMS is added, the more amino groups are introduced; however, the utilization rate of APTMS decreases. The ratio of 1:1 shown is the optimal ratio.

[0038] Preparation Example 5: This example differs from Preparation Example 1 in that

[0039] The mass-to-volume ratio of the silylation product to thioglycolic acid is 1:0.5 (g:mL).

[0040] Preparation Example 6: This example differs from Preparation Example 1 in that

[0041] The mass-to-volume ratio of the silylation product to thioglycolic acid is 1:2 (g:mL).

[0042] Preparation Example 7: This example differs from Preparation Example 1 in that:

[0043] The mass-to-volume ratio of the silylation product to thioglycolic acid is 1:3 (g:mL).

[0044] The results show that the more thioglycolic acid is added, the more adsorption sites are introduced; however, the utilization rate of thioglycolic acid decreases. The above ratio is the optimal ratio. The ratio of 1:1 shown is the optimal ratio.

[0045] Preparation Example 8: This example differs from Preparation Example 1 in that:

[0046] The mass ratio of CTAB to urea is 1:0.4.

[0047] Preparation Example 9: This example differs from Preparation Example 1 in that:

[0048] The mass ratio of CTAB to urea is 1:1.5.

[0049] Preparation Example 10: This Example differs from Preparation Example 1 in that:

[0050] The mass ratio of CTAB to urea is 1:3.

[0051] The results show that the addition of CTAB affects the formation of mesopores. The more CTAB is added, the easier it is to form mesopores, but the strength of DMSN decreases. Therefore, the ratio of 1:0.6 is the optimal ratio.

[0052] Verification Example 1

[0053] Verification Example 1: Verify the effect of solution pH on the adsorption of Hg(II) by the composite adsorption material TGC@DMSN.

[0054] The pH value of the water environment is complex and varies greatly, so the present invention studies the effect of pH on the adsorption of Hg(II) by the composite adsorbent material TGC@DMSN. The effect of different pH values ​​(2-10) on the adsorption of Hg(II) by the composite adsorbent material TGC@DMSN is shown in Figure 2. Figure 2 As shown in the figure, the adsorption capacity of the composite adsorbent material TGC@DMSN for Hg(II) gradually increases when the pH value ranges from 2 to 8, and the adsorption capacity is relatively stable when the pH value ranges from 8 to 10, indicating that under alkaline conditions, the effect of pH value on the adsorption of Hg(II) by the composite adsorbent material TGC@DMSN is not obvious.

[0055] Verification Example 2: Verify the effect of the initial mercury concentration of the composite adsorption material TGC@DMSN on the adsorption of Hg(II).

[0056] The adsorption capacity of the composite adsorbent material TGC@DMSN for Hg(II) was determined at an initial Hg(II) concentration of 25-300 ppm. Figure 3 As shown in the figure, the maximum adsorption capacity of the composite adsorbent material TGC@DMSN for Hg(II) is 257.1 mg / g, indicating that the prepared composite adsorbent material TGC@DMSN has excellent adsorption performance for Hg(II).

[0057] Verification Example 3: Verification of the recycling of the composite adsorption material TGC@DMSN.

[0058] The recovery of Hg(II) adsorbed by the composite adsorbent material TGC@DMSN is crucial in practical applications, and measures need to be taken to avoid secondary pollution. The composite adsorbent material TGC@DMSN after adsorption of Hg(II) is soaked and eluted with 0.1 mol / L hydrochloric acid, and then the material is dried and re-adsorbed, such as Figure 4 As shown in the figure, after five cycles, the adsorption capacity of the composite adsorbent material TGC@DMSN for Hg(II) can still reach 120 mg / g, indicating that the composite adsorbent material TGC@DMSN has good recycling performance and broad application prospects.

[0059] Verification Example 4: Verify the effects of ambient temperature and contact time on the adsorption of Hg(II) by the composite adsorption material TGC@DMSN.

[0060] During the adsorption process, the time to reach adsorption equilibrium is of great significance for evaluating the performance of the adsorption material. The adsorption capacity of the composite adsorbent material TGC@DMSN for Hg(II) was measured from 0 to 120 min at 25°C, 35°C, and 45°C and pH 8. Figure 6 The adsorption capacity of the composite adsorbent material TGC@DMSN for Hg(II) gradually increases with time and reaches adsorption equilibrium in about 20 minutes, indicating that the prepared composite adsorbent material TGC@DMSN has a high adsorption rate for Hg(II) and has a high adsorption capacity for Hg(II) in a very short time. At the same time, the increase in temperature promotes the adsorption reaction, indicating that the adsorption process is an endothermic process.

[0061] Verification Example 5: Verify the specific surface area and pore volume analysis of the composite material.

[0062] The structural characteristics of the adsorbent material were studied using the BET analysis method, such as Figure 6 The N2 adsorption-desorption isotherms of DMSN and TGA@DMSN composites are shown, and the relevant parameters are listed in Table 1 below.

[0063] Table 1

[0064]

[0065] Compared with the unfunctionalized DMSN, the composite material TGA@DMSN prepared by TGA functionalized DMSN has a specific surface area of ​​422.6m 2 / g becomes 125.5m 2 / g, and the average pore volume decreased from 0.74 to 0.43. This indicates that the successful introduction of thioglycolic acid onto the DMSN surface reduced the specific surface area and average pore volume of the composite. The average pore diameter increased from 7.88 nm to 14.11 nm, likely due to the larger micropores formed on the DMSN surface by the introduction of thioglycolic acid.

[0066] The carboxyl groups contained in the present invention can combine with the amino groups on the carrier to form covalent bonds and thus be grafted onto the carrier, and the relatively small molecular weight can graft more thioglycolic acid onto the carrier, further improving the adsorption capacity of the composite material.

[0067] This method uses silanization to grow amino groups on the surface of dendritic mesoporous SiO2. Then, through an amidation reaction, thioglycolic acid is grafted onto the silanized dendritic mesoporous SiO2, resulting in the composite adsorption material TGC@DMSN. This material can effectively remove mercury (Hg) from water and has promising application prospects in environmental water purification.

[0068] The present invention combines thioglycolic acid, a small organic molecule containing thiol and carboxyl groups, with a novel mesoporous nanomaterial, DMSN. Compared to traditional mesoporous materials, this novel "dendritic" porous material exhibits an unconventional open pore structure, relatively large pore size, and uniform particle size. Furthermore, the thiol groups contained in thioglycolic acid can be used for efficient removal of mercury (Hg) in water. The carboxyl groups can form covalent bonds with amino groups on a support, thereby grafting the material onto the support. The relatively small molecular weight allows more thioglycolic acid to be grafted onto the support. DMSN is prepared using CTAB and urea as templates and TEOS as a silicon source, and the template is removed by calcination.

Claims

1. A composite adsorption material for efficient purification of Hg (II), characterized in that: The preparation method of the composite adsorption material comprises the following steps: S1. Dispersing DMSN in toluene, and then adding APTMS thereto, the resulting mixture is refluxed at 130-140°C for 20-24 hours, and the silanized product APTMS@DMSN is obtained by centrifugation; the DMSN is prepared using CTAB and urea as templates and TEOS as a silicon source, and the mass-to-volume ratio of the DMSN to APTMS is 1 g: (0.5-2) mL; the mass ratio of CTAB to urea is 1:0.4-1:1.5; the DMSN preparation method is as follows: 1.0 g CTAB and 0.6 g urea are dissolved in distilled water, 30.0 mL cyclohexane and 1.5 mL n-pentanol are added and stirred to form a microemulsion, 10.0 mL TEOS is added, and the mixture is stirred at 330-350 rpm for 2.5-3 hours, and then the stirring is continued at 110-120°C for 3.5-4 hours. Finally, the product is calcined at 540-550°C for 5-6 hours to obtain DMSN; S2. The silanized product APTMS@DMSN obtained in step S1 and thioglycolic acid are dispersed in xylene, heated under reflux at 110-120° C. for 20-24 h, washed and dried to obtain the composite adsorption material TGC@DMSN; the mass to volume ratio of the silanized product to thioglycolic acid is 1 g: (0.5–2) mL.

2. The composite adsorption material for efficient purification of Hg(II) according to claim 1, characterized in that: The mass-to-volume ratio of DMSN to APTMS in step S1 was 1 g:1 mL.

3. The composite adsorption material for efficient purification of Hg(II) according to claim 1, characterized in that: The mass-to-volume ratio of the silylation product to thioglycolic acid in step S2 is 1 g: 1 mL.

4. Use of the composite adsorption material for efficiently purifying Hg (II) as claimed in claim 1 in the adsorption of Hg (II).

5. The use according to claim 4, characterized in that: Under the conditions of pH = 8 and an initial Hg(II) concentration of 100 ppm, TGC@DMSN was immersed in water containing Hg(II) for 20 min.

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