A method for removing heavy metals from water bodies by using supramolecular hydrogel

Abstract

The application belongs to the technical field of water body remediation, and particularly relates to a method for removing heavy metals in water bodies by using supramolecular hydrogel. The supramolecular hydrogel used in the application is amino clay and carboxymethyl beta-cyclodextrin supramolecular hydrogel. The supramolecular hydrogel used in the application has charges and a porous structure, can produce adsorption on heavy metal ions, and can remove heavy metal ions in water bodies, has high environmental remediation efficiency, has a short remediation period, and has a water body heavy metal ion removal rate of more than 99% at 14 days. The supramolecular hydrogel used in the application has high-performance capture of chemical pollutants based on the porous structure and orthogonal non-covalent interaction-electrostatic interaction, and can be an efficient platform for sustainable water body environmental remediation.

Description

Technical Field

[0001] This invention belongs to the field of environmental remediation technology, specifically relating to a method for removing heavy metals from water using supramolecular hydrogels. Background Technology

[0002] With industrial development, pollution of aquatic environments by heavy metals such as cadmium (Cd) has become increasingly serious. Phytoremediation, as a form of bioremediation, has attracted widespread attention due to its advantages such as being environmentally friendly, sustainable, low-cost, having lasting effects, and being easy to implement.

[0003] However, phytoremediation has limitations in the remediation of heavy metal pollution, such as long remediation cycles and low efficiency, which restricts its practical application. Summary of the Invention

[0004] The purpose of this invention is to provide a method for removing heavy metals from water using supramolecular hydrogels. The method provided by this invention has a short remediation cycle and high remediation efficiency, with a heavy metal ion removal rate of over 99% in water after 14 days.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for removing heavy metals from soil or water using supramolecular hydrogels, comprising the following steps: adding supramolecular hydrogels to the water body to be remediated for adsorption;

[0007] The building blocks of the supramolecular hydrogel include carboxymethyl β-cyclodextrin and amino clay that interacts with the carboxymethyl β-cyclodextrin via electrostatic interaction.

[0008] Preferably, the adsorption time is more than one day.

[0009] Preferably, the mass ratio of the supramolecular hydrogel to the heavy metals in the water to be remediated is 6 to 75:1.

[0010] Preferably, the adsorption temperature is 20–30°C.

[0011] Preferably, the mass ratio of carboxymethyl β-cyclodextrin to amino clay is 30-40:19-32.

[0012] Preferably, the method for preparing the supramolecular hydrogel includes the following steps: mixing carboxymethyl-β-cyclodextrin and a first water to obtain a stock solution; mixing the stock solution, amino clay, and a second water to form a solid, thereby obtaining the supramolecular hydrogel.

[0013] Preferably, the solidification process further includes freeze-drying the resulting product after allowing it to stand; the freeze-drying process includes a pre-cooling stage and a drying stage in sequence.

[0014] Preferably, the temperature of the pre-cooling stage is not higher than -40°C, and the heat preservation and pre-cooling time is 1 to 1.5 hours.

[0015] Preferably, the temperature of the drying stage is -70 to -50°C, and the heat preservation and drying time is 48 to 72 hours.

[0016] Preferably, the settling time is 4 to 32 hours.

[0017] This invention provides a method for removing heavy metals from water using supramolecular hydrogels. The supramolecular hydrogel used in this invention is an amino clay (AC) and carboxymethyl β-cyclodextrin (CM-β-CD) supramolecular hydrogel, structurally represented as CM-β-CD@AC. The supramolecular hydrogel used in this invention is charged and has a porous structure, enabling the adsorption of heavy metal ions and achieving the removal of heavy metal ions from water. This method offers high environmental remediation efficiency and a short remediation cycle, with a heavy metal ion removal rate of over 99% in water after 14 days.

[0018] The supramolecular hydrogel used in this invention is based on a porous structure and orthogonal non-covalent interactions—electrostatic interactions—which have superior performance in efficiently capturing chemical pollutants, giving it the potential for sustainable aquatic environment remediation. Detailed Implementation

[0019] This invention provides a method for removing heavy metals from water using supramolecular hydrogels, comprising the following steps:

[0020] Add supramolecular hydrogels to the water body to be remediated for adsorption;

[0021] The building blocks of the supramolecular hydrogel include carboxymethyl β-cyclodextrin and amino clay that interacts with the carboxymethyl β-cyclodextrin via electrostatic interaction.

[0022] In this invention, the heavy metals in the water body to be restored may include one or more of lead, copper, and cadmium.

[0023] In this invention, the concentration of heavy metals in the water body to be remediated may not exceed 17.8 mmol / L, specifically it may be 0.5 mmol / L, 1 mmol / L, 5 mmol / L, 10 mmol / L or 15 mmol / L.

[0024] In this invention, the building blocks of the supramolecular hydrogel include carboxymethyl β-cyclodextrin; the structure of the carboxymethyl β-cyclodextrin is shown in Formula A:

[0025]

[0026] In this invention, the building unit of the supramolecular hydrogel includes amino clay that interacts electrostatically with the carboxymethyl β-cyclodextrin; the mass ratio of the carboxymethyl β-cyclodextrin to the amino clay can be 30-40:19-32, specifically 30:19, 30:25, 30:32, 40:19, 40:25 or 40:32.

[0027] In this invention, the preparation method of the supramolecular hydrogel may include the following steps: mixing carboxymethyl-β-cyclodextrin and a first water to obtain a stock solution; mixing the stock solution, amino clay, and a second water to form a solidification solution to obtain the supramolecular hydrogel.

[0028] In this invention, carboxymethyl-β-cyclodextrin and a first water are mixed to obtain a stock solution. In this invention, the first water is preferably deionized water.

[0029] In this invention, the preferred molar volume ratio of carboxymethyl-β-cyclodextrin to the first water is 10 mmol:(9-12) mL, specifically 10 mmol:9 mL, 10 mmol:10 mL, 10 mmol:11 mL or 10 mmol:12 mL.

[0030] After obtaining the stock solution, the present invention mixes the stock solution, amino clay, and second water (denoted as the first mixture) to form a solidified mixture, thereby obtaining the supramolecular hydrogel. In the present invention, the preparation method of the amino clay (AC) preferably refers to Chinese Patent CN112011098A.

[0031] In this invention, the second water is preferably deionized water.

[0032] In this invention, the first mixing is preferably: stirring and mixing amino clay and water (referred to as stirring A) until the solution is clear to obtain an aqueous solution of amino clay, and continuing to stir and mix the stock solution and the aqueous solution of amino clay (referred to as stirring B).

[0033] In this invention, the preferred mass-to-volume ratio of the amino clay to the stock solution is (0.3-0.4) g:(0.15-0.25) mL, specifically 0.3 g:0.15 mL, 0.35 g:0.15 mL, 0.4 g:0.15 mL, 0.3 g:0.2 mL, 0.35 g:0.2 mL, 0.4 g:0.2 mL, 0.3 g:0.25 mL, 0.35 g:0.25 mL, or 0.4 g:0.25 mL.

[0034] In this invention, the volume ratio of the reserve liquid to the second water is preferably 0.15 to 0.25:1, specifically 0.15:1, 0.17:1, 0.19:1, 0.21:1, 0.23:1 or 0.25:1.

[0035] In this invention, the molar concentration of the stock solution is preferably 0.8 to 1.1 mol / L, specifically 0.8 mol / L, 0.9 mol / L, 1 mol / L or 1.1 mol / L.

[0036] In this invention, the stirring speed of the stirring A is preferably 480 to 960 rpm, specifically 480 rpm, 600 rpm, 720 rpm, 840 rpm or 960 rpm, and the stirring time is preferably 20 to 40 min, specifically 25 min, 30 min or 35 min.

[0037] In this invention, the stirring speed of the stirring B is preferably 480 to 960 rpm, specifically 480 rpm, 600 rpm, 720 rpm, 840 rpm or 960 rpm, and the stirring time is preferably 10 to 15 min, specifically 11 min or 12 min.

[0038] In this invention, the condensation temperature is preferably 15-40°C, specifically 20°C or 25°C.

[0039] In this invention, the solidification process preferably further includes freeze-drying the resulting product after allowing it to stand.

[0040] In this invention, the settling time is preferably 4 to 32 hours, specifically 12 hours or 24 hours.

[0041] In this invention, the freeze-drying preferably includes a pre-cooling stage and a drying stage in sequence; the temperature of the pre-cooling stage is preferably not higher than -40°C, specifically -40°C, -45°C, -50°C, -55°C or -60°C, and the pre-cooling time is preferably 1 to 1.5 hours, specifically 1 hour, 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours or 1.5 hours.

[0042] In this invention, the temperature of the drying stage is preferably -70 to -50°C, specifically -70°C, -65°C, -60°C, -55°C or -50°C, and the heat preservation and drying time is preferably 48 to 72 hours, specifically 48 hours, 54 hours, 60 hours, 66 hours or 72 hours; the freeze-drying equipment is preferably a freeze dryer.

[0043] In this invention, the mass ratio of the supramolecular hydrogel to the heavy metals in the water to be remediated can be 6–75:1, specifically 6:1, 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1, 54:1, 60:1, 70:1, or 75:1. By adding the above-mentioned amounts of supramolecular hydrogel, this invention helps to improve the adsorption effect of heavy metals.

[0044] In this invention, the adsorption time can be more than one day, specifically one day, two days, five days, ten days, fifteen days, twenty days, thirty days, forty days or fifty days.

[0045] In this invention, the adsorption temperature can be 20 to 30°C, specifically 20°C, 22°C, 24°C, 26°C, 28°C or 30°C.

[0046] To further illustrate the present invention, the following detailed description of the embodiments is provided in conjunction with the present invention, but these descriptions should not be construed as limiting the scope of protection of the present invention.

[0047] Example 1

[0048] This embodiment prepares a supramolecular hydrogel, and the preparation method includes the following steps:

[0049] (1) Preparation of amino clay, the synthesis route is based on Chinese patent CN112011098A: Weigh 10.08 g of magnesium chloride hexahydrate and 3-aminopropyltriethoxysilane, dissolve them in 240 mL of anhydrous ethanol, stir slowly for 24 h, centrifuge at 4000 r / min for 8 min to collect the white precipitate, wash it 3 times with ethanol, dry it under vacuum at 40 °C for 48 h, grind it to obtain amino clay, which is a light yellow powder.

[0050] (2) Preparation of stock solution: Carboxymethyl-β-cyclodextrin was added to deionized water and stirred to dissolve. The solution was sonicated for 1 hour to ensure complete dissolution. The ratio of carboxymethyl-β-cyclodextrin to deionized water was 10 mmol: 9 mL to obtain the stock solution with a concentration of 1.1 mol / L.

[0051] (3) Take 0.4g of amino clay from step (1) and add it to deionized water. Stir at 900r / min for 20min until the solution becomes clear. Add the stock solution from step (2) to the above solution and continue stirring for 15min. The ratio of the amount of amino clay, stock solution and deionized water added is 0.4g:0.15mL:1mL. Let stand for 12h and freeze dry at -60℃ for 72h to obtain powdered supramolecular hydrogel.

[0052] Application Example 1

[0053] This application example uses the supramolecular hydrogel prepared in Example 1 to remove cadmium from the water body to be remediated. The specific steps are as follows:

[0054] 0.7354 g of supramolecular hydrogel was added to 150 mL of water to be remediated. The Cd concentration in the water before remediation was 67.25 ± 2.47 mg / L. After 14 days of adsorption, the cadmium concentration in the water was measured and the cadmium removal rate was calculated. To ensure the repeatability and reliability of the results, the experiment was repeated 3 times and the average value was taken. The results are shown in Table 1.

[0055] Table 1. Cd removal results in Application Example 1

[0056] Cd concentration in the water before adsorption (mg / L) Cd concentration in the water after adsorption (mg / L) 67.25±2.47 0.55±0.15

[0057] As can be seen from Table 1, the supramolecular hydrogel provided by the present invention effectively removes cadmium ions from water, with a removal rate of 99.2%.

[0058] Application Example 2

[0059] The method used in this application example is the same as that in application example 1, except that the amount of supramolecular hydrogel added is 0.2770 g. The results are shown in Table 2.

[0060] Table 2 shows the Cd removal results in Application Example 2.

[0061] Cd concentration in the water before adsorption (mg / L) Cd concentration in the water after adsorption (mg / L) 67.25±2.47 0.28±0.01

[0062] As shown in Table 2, the supramolecular hydrogel effectively removed cadmium ions from the water, with a removal rate of 99.6%.

[0063] Application Example 3

[0064] The method used in this application example is the same as that in application example 2, except that the amount of supramolecular hydrogel added is 0.3677 g. The results are shown in Table 3.

[0065] Table 3. Cd removal results in Application Example 3

[0066] Cd concentration in the water before adsorption (mg / L) Cd concentration in the water after adsorption (mg / L) 67.25±2.47 0.40±0.01

[0067] As shown in Table 3, the supramolecular hydrogel effectively removed cadmium ions from the water, with a removal rate of 99.4%.

[0068] Application Example 4

[0069] The method used in this application example is the same as that in application example 1, except that the amount of supramolecular hydrogel added is 0.7078g. The results are shown in Table 4.

[0070] Table 4 shows the Cd removal results in Application Example 4.

[0071] Cd concentration in the water before adsorption (mg / L) Cd concentration in the water after adsorption (mg / L) 67.25±2.47 0.27±0.03

[0072] As shown in Table 4, the supramolecular hydrogel effectively removed cadmium ions from the water, with a removal rate of 99.6%.

[0073] Application Example 5

[0074] The method used in this application example is the same as that in application example 1, except that the amount of supramolecular hydrogel added is 0.2666g. The results are shown in Table 5.

[0075] Table 5 shows the Cd removal results in Application Example 5.

[0076] Cd concentration in the water before adsorption (mg / L) Cd concentration in the water after adsorption (mg / L) 67.25±2.47 0.43±0.02

[0077] As shown in Table 5, the supramolecular hydrogel effectively removed cadmium ions from the water, with a removal rate of 99.36%.

[0078] As can be seen from the above embodiments, the method provided by the present invention can effectively remove heavy metal ions from water bodies, with a removal rate of over 99% after 14 days. It can quickly and effectively restore polluted water bodies and is of great significance for water resource utilization.

[0079] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for removing heavy metals from water using supramolecular hydrogels, characterized in that, Includes the following steps: Add supramolecular hydrogels to the water body to be remediated for adsorption; The building blocks of the supramolecular hydrogel include carboxymethyl β-cyclodextrin and amino clay that interacts with the carboxymethyl β-cyclodextrin via electrostatic interaction. The mass ratio of carboxymethyl β-cyclodextrin to amino clay is 30~40:19~32.

2. The method according to claim 1, characterized in that, The adsorption time is more than one day.

3. The method according to claim 1, characterized in that, The mass ratio of the supramolecular hydrogel to the heavy metals in the water to be remediated is 6~75:

1.

4. The method according to claim 1 or 2, characterized in that, The adsorption temperature is 20~30℃.

5. The method according to claim 1, characterized in that, The preparation method of the supramolecular hydrogel includes the following steps: mixing carboxymethyl-β-cyclodextrin and first water to obtain a stock solution; mixing the stock solution, amino clay and second water to form a solidification solution to obtain the supramolecular hydrogel.

6. The method according to claim 5, characterized in that, The process after solidification also includes freezing-drying the resulting product after allowing it to stand; the freeze-drying process includes a pre-cooling stage and a drying stage in sequence.

7. The method according to claim 6, characterized in that, The temperature during the pre-cooling stage shall not exceed -40℃, and the heat preservation and pre-cooling time shall be 1~1.5h.

8. The method according to claim 6 or 7, characterized in that, The temperature during the drying stage is -70 to -50°C, and the drying time is 48 to 72 hours.

9. The method according to claim 6, characterized in that, The settling time is 4 to 32 hours.

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