Preparation process of high-efficiency heavy metal ion capturing agent in wastewater

Abstract

The application relates to the technical field of wastewater treatment, and particularly discloses a preparation process of a heavy metal ion high-efficiency trapping agent in wastewater, which comprises the following steps: (1) Fe-MOF powder is heated by infrared irradiation in a protective atmosphere, then the atmosphere is switched to an oxygen-containing atmosphere, the temperature is increased, and the powder is kept warm, and after the completion, the powder is naturally cooled to room temperature, so that gamma-Fe2O3@MOF powder is obtained; (2) the gamma-Fe2O3@MOF powder is dispersed into anhydrous ethanol to form a suspension, then the suspension is adjusted to be alkaline, carbon disulfide is added, and the suspension is reacted under ultrasonic treatment. After the completion, the solid product is separated, washed and dried, so that the trapping agent is obtained. The application not only greatly improves the removal effect of the heavy metal ions in the wastewater by utilizing the surface adsorption and internal packaging characteristics of the prepared trapping agent, but also can conveniently recover the trapping agent from the water body, so that secondary pollution to the water body is avoided.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a preparation process for a highly efficient heavy metal ion capture agent in wastewater. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that the information has become prior art known to those skilled in the art.

[0003] Industrial wastewater is a major source of heavy metal ion pollution, originating in various sectors including mining, electroplating, chemical engineering, electronics manufacturing, and metallurgy. For example, during non-ferrous metal mining and smelting, heavy metals such as Cr, Pb, and Cd from the ore enter water bodies via flushing water and tailings wastewater. Cyanide plating solutions and acidic plating solutions from the electroplating industry discharge Cu-containing wastewater. 2+ Ni 2+ Hg 2+ Wastewater from the production of vinyl chloride and acetaldehyde in the chemical industry. Leakage or disposal of mercury catalysts can lead to the production of Hg. 2+ It enters wastewater. Circuit board etching and battery production in the electronics industry release Pb. 2+ Cd 2+ Pollutants such as these heavy metal ions cannot be biodegraded naturally and will remain in water bodies for a long time. They will accumulate step by step through the food chain of "aquatic organisms-fish-humans", ultimately harming the ecosystem and human health.

[0004] From the perspective of hazard characteristics, different heavy metal ions have different toxic targets. 2+ Its toxicity is particularly pronounced; even at extremely low concentrations (μg / L), it can penetrate the bloodstream and reach the brain, damaging the central nervous system. Currently, my country's "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants" (GB18918-2002) has extremely strict emission limits for heavy metal ions, among which Hg... 2+ The maximum permissible emission concentration is only 0.001 mg / L, far lower than that of other heavy metals (such as Cr). 6+ 0.05 mg / L, Pb 2+ The concentration was 0.1 mg / L, which further increased the difficulty of processing.

[0005] Hg 2+ The removal of Hg is currently a key focus and challenge in the field of wastewater treatment. Firstly, Hg... 2+ It readily reacts with CN in wastewater. - Cl - The anions form stable complex ions (such as [Hg(CN)4)). 2- [HgCl4] 2-These complexes have a much higher solubility than pure Hg. 2+ Conventional chemical precipitation methods (such as adding sodium sulfide) can only remove free Hg. 2+ For complexed Hg 2+ The removal rate is less than 30%, making it difficult to meet emission standards. Secondly, Hg... 2+ The treatment needs to balance "low concentration" and "deep removal". After preliminary treatment, industrial wastewater... 2+ When the concentration drops to 0.01~0.1 mg / L, the adsorbent in the adsorption method easily reaches saturation, and the selectivity of the ion exchange resin is insufficient. Multiple cycles are required to reduce the concentration below 0.001 mg / L, resulting in low treatment efficiency and high energy consumption. Furthermore, coexisting ions in the wastewater significantly interfere with Hg levels. 2+ Removal, such as high concentrations of Cu 2+ Zn 2+ Will with Hg 2+ Competing for active sites on the adsorbent surface, making Hg 2+ The adsorption capacity decreases by 40-60%, and mercury-containing wastewater is often accompanied by the discharge of other heavy metals, further increasing the difficulty of treatment. Finally, Hg 2+ The treated residue poses a risk of secondary pollution. Even mercuric sulfide (HgS) precipitate can slowly dissolve Hg under acidic conditions (pH < 4). 2+ The residue needs to be solidified and stabilized (e.g., by adding cement or glass hardener), but this process is costly and cannot completely eliminate the environmental risks of mercury, leading to Hg... 2+ Deep removal of pollutants has become a challenge in the field of industrial wastewater treatment. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a preparation process for a highly efficient heavy metal ion trapping agent in wastewater. This process not only significantly improves the removal efficiency of heavy metal ions from wastewater by utilizing the surface adsorption and internal encapsulation properties of the prepared trapping agent, but also allows for convenient recovery of the trapping agent from the water body, avoiding secondary pollution. Specifically, the technical solution of this invention is as follows.

[0007] A preparation process for a highly efficient heavy metal ion collector in wastewater includes the following steps:

[0008] (1) The Fe-MOF powder was heated by infrared irradiation in a protective atmosphere and kept at that temperature. Then, the temperature was increased and kept at that temperature after switching to an oxygen-containing atmosphere. After the process was completed, it was naturally cooled to room temperature to obtain γ-Fe2O3@MOF powder.

[0009] (2) The γ-Fe2O3@MOF powder is dispersed in an alcoholic liquid to form a suspension. The suspension is then adjusted to alkaline, carbon disulfide (CS2) is added, and the reaction is carried out under ultrasonic treatment. After completion, the solid product is separated, washed, and dried to obtain the scavenger grafted with dithiocarbamate (DTC) groups.

[0010] Furthermore, in step (1), the heating temperature is 200~250℃ and the holding time is 1~2h. During this process, photogenerated carriers are used to adjust the electronic state and coordination environment of Fe sites in the Fe-MOF, thereby accurately forming Fe activation points.

[0011] Further, in step (1), the volume fraction of oxygen in the oxygen-containing atmosphere is maintained between 5% and 10%. Optionally, the oxygen-containing atmosphere is formed by reacting oxygen with at least one of nitrogen, argon, etc.

[0012] Further, in step (1), after switching to the oxygen-containing atmosphere, the temperature is raised to 250~300℃ and then kept at that temperature for 2~4 hours. This step utilizes oxygen to precisely convert the Fe activation point to γ-Fe2O3.

[0013] Further, in step (2), the ratio of γ-Fe2O3@MOF to the alcohol liquid is 1g:150~300mL. Optionally, the alcohol liquid includes at least one of anhydrous methanol, anhydrous ethanol, isopropanol, etc.

[0014] Furthermore, in step (2), the suspension is adjusted to be alkaline by using at least one of sodium carbonate, potassium carbonate, sodium bicarbonate, etc.

[0015] Further, in step (2), the mass ratio of carbon disulfide to γ-Fe2O3@MOF is 1.2~2:1.

[0016] Furthermore, in step (2), the pH of the system is maintained between 8 and 8.5 during the reaction process. Optionally, the reaction time is 6 to 8 hours.

[0017] Further, in step (2), the washing method includes: alternately washing the solid product with anhydrous ethanol and deionized water as cleaning agents. Optionally, the number of times each cleaning agent is used is 3 to 5.

[0018] Furthermore, in step (2), the drying temperature is 60~80℃ and the time is 4~12h.

[0019] Further, in step (1), the Fe-MOF powder is prepared by the following method:

[0020] (i) An iron source and aminophenylacetic acid (APA) were dissolved in N,N-dimethylformamide to form a precursor solution, and then the metal-organic framework material ZIF-7 was added and ultrasonically treated under heating conditions. After completion, the product was irradiated with ultraviolet light, and then the solid product was separated and washed to obtain the template-containing product.

[0021] (ii) A ZnO layer containing hydroxyl groups is deposited on the surface of the template product to obtain a secondary modified template material.

[0022] (iii) The modified template material is added again to the precursor solution in step (1) and then ultrasonically treated under heating conditions. After completion, it is irradiated with ultraviolet light, then the solid product is separated and annealed, and finally the obtained product is acid-washed and then washed to obtain the Fe-MOF powder.

[0023] Further, in step (i), the concentration of the iron source in the precursor solution is 0.1~0.6 mol / L. Optionally, the iron source includes at least one of ferric nitrate, ferric chloride, etc.

[0024] Further, in step (i), the precursor solution contains 0.1~0.5 mol / L of aminophenylacetic acid (APA).

[0025] Further, in step (i), the mass ratio of the metal-organic framework material ZIF-7 to the iron source is 1~2:1.

[0026] Further, in step (ii), the thickness of the ZnO layer is 5-10 nm. Optionally, the ZnO can be formed from at least one zinc source such as diethylzinc (DEZ). The arc pair electrons of the O in the hydroxyl group can bind to the Fe provided by the iron source. 3+ Attraction trapping is performed to construct Fe-MOF structures.

[0027] Further, in step (iii), the mass ratio of the secondary modified template material to the iron source is 1~2:1.

[0028] Furthermore, in steps (i) and (iii), the heating temperature is 60~80℃ and the ultrasonic treatment time is 1~2 hours.

[0029] Further, in steps (i) and (iii), the irradiation time is 6-8 hours. Optionally, the wavelength of the ultraviolet light is 200-280 nm.

[0030] Furthermore, in step (iii), the annealing treatment is performed at a temperature of 240~280℃ for 1~3 hours.

[0031] Further, in step (iii), the acid washing method can be: adding the product to an acid solution and stirring, changing the acid solution during the process, until Zn is no longer detectable in the acid solution. 2+ The presence of the acid completes the pickling process. Optionally, the concentration of the acid solution is 0.1~0.5 mol / L; the acid solution includes at least one of acetic acid, citric acid, etc.

[0032] Further, in steps (i) and (iii), the washing method is as follows: the product is soaked in ethanol with mass fractions of 30%, 50%, 70%, 90%, and 99% in sequence, and then critical point drying is performed to obtain the product. Optionally, the soaking time is 10-20 minutes.

[0033] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects:

[0034] (1) This invention uses infrared irradiation to treat Fe-MOF materials, thereby accurately converting the Fe sites in Fe-MOF into superparamagnetic γ-Fe2O3 without affecting the structural characteristics of Fe-MOF. This allows the trapping agent of this invention to be easily recovered from wastewater by an external magnetic field, avoiding secondary pollution of the wastewater. At the same time, iron and the trapped heavy metal elements can be recovered by high-temperature pyrolysis of the recovered trapping agent. This is because after the iron atoms in the Fe-MOF are irradiated with infrared light, their photogenerated charge carriers can regulate the electronic state and coordination environment of the Fe atoms, thereby accurately converting them into Fe activation points, which are convenient for reacting with oxygen to form γ-Fe2O3 in subsequent processes. In the above process, the destruction of the three-dimensional cage-like special structure of the Fe-MOF material prepared by this invention is avoided to the greatest extent. This structure can not only efficiently adsorb heavy metal ions in wastewater, but also encapsulate them inside, significantly improving the adsorption capacity of heavy metal ions and improving the wastewater purification effect. Furthermore, the present invention grafts dithiocarbamate (DTC) groups onto the trapping agent, which is capable of targeting Hg in wastewater. 2+ Chelation forms stable compounds, improving capture efficiency.

[0035] (2) In this invention, the metal-organic framework material ZIF-7 is first immersed in a precursor solution for in-situ crystallization, and then ultraviolet light irradiation is used to excite the hydrated Fe in the crystals. 3+ Electron transitions promote the dissociation of water molecules and increase Fe 3+ This activity makes it easier for Fe to combine with the carboxyl groups (-COOH) of APA, allowing both to adhere to the ZIF-7 surface and penetrate into the template for crystallization. During this process, Fe... 3+APA adheres to the truncated octahedral topology of ZIF-7 and undergoes structural replication to form an inner shell. Then, the present invention deposits a ZnO layer containing hydroxyl groups on this inner shell, followed by a reaction with the precursor solution. At this point, Fe... 3+ APA is induced to attach to the ZnO layer, forming a continuous two-dimensional network topology that creates an outer shell. After the ZnO layer is subsequently removed by acid washing, an outer shell that can rotate relative to the inner shell and core is formed. When using this type of trap to treat mercury-containing wastewater, DTC on the trap first reacts with Hg... 2+ Complexation occurs simultaneously, and the free rotation of the core within the trap guides wastewater and mercury ions to frequently enter the trap, thus complexing the mercury ions and preventing the outer shell from preferentially complexing Hg. 2+ After ionization, the shell pores are gradually blocked, leading to low internal utilization. This is because when wastewater enters the interior through the pores of the outer shell, the impact on the core causes it to rotate freely relative to the outer shell. In addition, tiny particles undergo thermal motion (Brownian motion) in water. The different motion frequencies of the core and shell, along with their relative motion, draw wastewater into the core, preventing the shell pores from being blocked and thus avoiding low internal utilization. Attached Figure Description

[0036] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0037] Figure 1 The image shows the Fe-MOF powder sample prepared in Example 1 below.

[0038] Figure 2 The image shows a sample of the trapping agent prepared in Example 1 below.

[0039] Figure 3 The image shows a scanning electron microscope (SEM) image of the trapping agent prepared in Example 1 below.

[0040] Figure 4 Transmission electron microscopy (TEM) image of the trapping agent prepared in Example 1 below.

[0041] Figure 5 The image shows the Fe-MOF powder sample prepared in Example 2 below.

[0042] Figure 6 The image shows a sample of the trapping agent prepared in Example 2 below.

[0043] Figure 7 The image shows a scanning electron microscope (SEM) image of the trapping agent prepared in Example 2 below.

[0044] Figure 8Transmission electron microscopy (TEM) image of the trapping agent prepared in Example 2 below.

[0045] Figure 9 The image shows the Fe-MOF powder sample prepared in Example 3 below.

[0046] Figure 10 The image shows a sample of the trapping agent prepared in Example 3 below.

[0047] Figure 11 The image shows a scanning electron microscope (SEM) image of the trapping agent prepared in Example 3 below.

[0048] Figure 12 Transmission electron microscopy (TEM) image of the trapping agent prepared in Example 3 below.

[0049] Figure 13 The image shows the Fe-MOF powder sample prepared in Example 4 below.

[0050] Figure 14 The image shows a sample of the trapping agent prepared in Example 4 below.

[0051] Figure 15 The image shows a sample of the trapping agent prepared in Example 5 below.

[0052] Figure 16 The image shows a sample of the trapping agent prepared in Example 6 below.

[0053] Figure 17 The image shows the Fe-MOF powder sample prepared in Example 7 below.

[0054] Figure 18 The image shows a sample of the trapping agent prepared in Example 7 below. Detailed Implementation

[0055] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer.

[0056] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as those skilled in the art. The reagents or raw materials used in this invention are readily available through conventional means, and unless otherwise specified, they are used in accordance with conventional methods or product instructions. Furthermore, any methods and materials similar to or equivalent to those described herein can be applied to the methods of this invention. The technical solution of this invention will now be further described in conjunction with the accompanying drawings and specific embodiments.

[0057] Example 1: A preparation process for a highly efficient heavy metal ion collector in wastewater, comprising the following steps:

[0058] (1) An iron source (ferric nitrate) and aminophenylacetic acid were dissolved in N,N-dimethylformamide to form a precursor solution, wherein the concentration of the iron source was 0.1 mol / L and the concentration of aminophenylacetic acid was 0.1 mol / L. Then, a metal-organic framework material ZIF-7 was added to the precursor solution as a template, and the mass ratio of the template to the iron source was 1.5:1. The solution was then heated to 80°C in a water bath and held at that temperature for 1 hour, followed by ultrasonic treatment. Then, it was irradiated with ultraviolet light at a wavelength of 240 nm for 6.5 hours. After completion, the solid product was filtered out and then soaked in ethanol with mass fractions of 30%, 50%, 70%, 90%, and 99% for 15 minutes each. After completion, critical point drying was performed to obtain the template-containing product powder.

[0059] (2) A ZnO layer is deposited on the surface of the template-containing product by atomic layer deposition (ALD). The specific method is as follows: The template-containing product powder is placed on a rotating dynamic mixing tray in the deposition chamber and rotated at 10 rpm. Then, diethylzinc (DEZ) and deionized water are sputtered alternately onto the surface of the template-containing product powder particles for 0.1 s each time at a temperature of 150 °C. The above-mentioned cross-sputtering process is repeated to form a 10 nm thick ZnO layer rich in hydroxyl groups on the surface of the particles, thus obtaining a secondary modified template material.

[0060] (3) The modified template material is added again to the precursor solution in step (1), and the mass ratio of the modified template material to the iron source in the precursor solution is 1.5:1. Then, the solution is heated to 80°C in a water bath and held at that temperature for 1 hour. Then, it is irradiated with ultraviolet light at a wavelength of 240 nm for 6.5 hours. After completion, the solid product is filtered out, heated to 250°C and held for 2 hours for annealing, and then naturally cooled to room temperature. The resulting product is added to a 0.3 mol / L acetic acid aqueous solution and stirred continuously, with the acetic acid aqueous solution being replaced every 30 minutes until Zn is no longer detectable in the acid solution. 2+ The presence of [a specific ingredient] completes the acid washing process. The resulting product is then sequentially immersed in ethanol at concentrations of 30%, 50%, 70%, 90%, and 99% for 15 minutes each. After this, critical point drying is performed to obtain Fe-MOF powder, such as... Figure 1 As shown.

[0061] (4) The Fe-MOF powder was placed in a quartz sample stage and then placed in a reaction chamber. Nitrogen gas was introduced as a protective atmosphere, and then the mixture was heated to 230°C by infrared irradiation and held for 1.5 hours. The protective atmosphere was then switched to an oxygen-containing atmosphere composed of nitrogen and oxygen (oxygen volume fraction of 8%). After completion, the temperature was raised to 270°C and held for 3 hours. After completion, the mixture was allowed to cool naturally to room temperature to obtain γ-Fe2O3@MOF powder.

[0062] (5) The γ-Fe2O3@MOF powder and anhydrous ethanol were mixed at a ratio of 1g:200mL and stirred for 10min to form a suspension. Sodium carbonate solution was then added to adjust the pH of the suspension to 8.5. Carbon disulfide (CS2) was then added to the suspension using a constant-pressure dropping funnel at a molar ratio of 1.5:1 to the γ-Fe2O3@MOF. The mixture was then reacted under ultrasonic treatment for 6 hours. If the pH of the system dropped below 8 during the reaction, sodium carbonate solution was immediately added to ensure the pH remained above 8. After completion, the solid product was separated using an external magnetic field. The solid product was then washed alternately with anhydrous ethanol and deionized water, with each washing agent being applied 4 times. Finally, the product was vacuum dried at 60℃ for 12 hours to obtain the final product. Figure 2 The trapping agent shown has SEM and TEM images as follows: Figure 3 , Figure 4 As shown.

[0063] Performance testing: 1. The trapping agent prepared in this embodiment was added to Hg at an addition rate of 5.7 mg / L. 2+ In wastewater with an initial mercury concentration of 5.0012 mg / L, the Hg in the wastewater was determined by cold vapor atomic absorption spectrophotometry according to the test method in HJ 597-2011 "Determination of Total Mercury in Water - Cold Vapor Atom Absorption Spectrophotometry". 2+ The remaining amount, and calculate Hg. 2+ Removal rate. 2. A 0.5T magnetic field was used to separate the turbidity in the wastewater. Then, according to HJ 1075-2019 "Determination of Turbidity in Water - Turbidity Meter Method", the turbidity of the separated water was measured using a turbidity meter to measure the magnetic recovery effect of the turbidity. The higher the value, the worse the magnetic recovery effect. The test results are as follows: Hg 2+ Removal rate = 99.996%, water turbidity = 0.42 NTU.

[0064] Example 2: A preparation process for a highly efficient heavy metal ion collector in wastewater, comprising the following steps:

[0065] (1) An iron source (ferric nitrate) and aminophenylacetic acid were dissolved in N,N-dimethylformamide to form a precursor solution, wherein the concentration of the iron source was 0.3 mol / L and the concentration of aminophenylacetic acid was 0.4 mol / L. Then, a metal-organic framework material ZIF-7 was added to the precursor solution as a template, and the mass ratio of the template to the iron source was 1:1. The solution was then heated to 60°C in a water bath and held at that temperature for 2 hours, followed by ultrasonic treatment. Then, it was irradiated with ultraviolet light at a wavelength of 280 nm for 8 hours. After completion, the solid product was filtered out and then soaked in ethanol with mass fractions of 30%, 50%, 70%, 90%, and 99% for 15 minutes each. After completion, critical point drying was performed to obtain the template-containing product powder.

[0066] (2) A ZnO layer is deposited on the surface of the template-containing product by atomic layer deposition (ALD). The specific method is as follows: The template-containing product is placed on a rotating dynamic mixing tray in the deposition chamber and rotated at a speed of 10 rpm. Then, diethylzinc (DEZ) and deionized water are sputtered alternately onto the surface of the template-containing product powder particles. Each sputtering time is 0.1 s and the temperature is 150 °C. The above-mentioned cross-sputtering process is repeated to form a hydroxyl-rich ZnO layer with a thickness of 8 nm on the surface of the particles, thus obtaining a secondary modified template material.

[0067] (3) The modified template material is added again to the precursor solution in step (1), and the mass ratio of the modified template material to the iron source in the precursor solution is 1:1. Then, the solution is heated to 60°C in a water bath and held at that temperature for 2 hours, followed by ultrasonic treatment. Then, it is irradiated with ultraviolet light at a wavelength of 280 nm for 8 hours. After completion, the solid product is filtered out, heated to 240°C and held for 3 hours for annealing, and then naturally cooled to room temperature. The resulting product is added to a 0.1 mol / L acetic acid aqueous solution and stirred continuously, with the acetic acid aqueous solution being replaced every 20 minutes until Zn is no longer detectable in the acid solution. 2+ The presence of [a specific ingredient] completes the acid washing process. The resulting product is then sequentially immersed in ethanol at concentrations of 30%, 50%, 70%, 90%, and 99% for 10 minutes each. After this, critical point drying is performed to obtain Fe-MOF powder, such as... Figure 5 As shown.

[0068] (4) Place the Fe-MOF powder in a quartz sample stage, then place it in a reaction chamber, introduce nitrogen as a protective atmosphere, then heat it to 200°C by infrared irradiation and hold it for 2 hours. Then switch the protective atmosphere to an oxygen-containing atmosphere composed of nitrogen and oxygen (oxygen volume fraction of 5%). After completion, raise the temperature to 250°C and continue to hold it for 4 hours. After completion, allow it to cool naturally to room temperature to obtain γ-Fe2O3@MOF powder.

[0069] (5) The γ-Fe2O3@MOF powder and isopropanol were mixed at a ratio of 1g:150mL and stirred for 10min to form a suspension. Sodium bicarbonate solution was then added to adjust the pH of the suspension to 8. Carbon disulfide (CS2) was then added to the suspension using a constant-pressure dropping funnel at a molar ratio of 1.2:1 to the γ-Fe2O3@MOF. The mixture was then reacted under ultrasonic treatment for 7 hours. If the pH of the system dropped below 8 during the reaction, sodium bicarbonate solution was immediately added to ensure the pH remained above 8. After completion, the solid product was separated using an external magnetic field. The solid product was then washed alternately with anhydrous ethanol and deionized water, with each washing agent applied three times. Finally, the product was vacuum dried at 80℃ for 4 hours to obtain the final product. Figure 6 The trapping agent shown has SEM and TEM images as follows: Figure 7 , Figure 8 As shown.

[0070] Performance testing: 1. The trapping agent prepared in this embodiment was added to Hg at an addition rate of 6.2 mg / L. 2+ In wastewater with an initial mercury concentration of 5.0012 mg / L, the Hg in the wastewater was determined by cold vapor atomic absorption spectrophotometry according to the test method in HJ 597-2011 "Determination of Total Mercury in Water - Cold Vapor Atom Absorption Spectrophotometry". 2+ The remaining amount, and calculate Hg. 2+ Removal rate. 2. A 0.5T magnetic field was used to separate the turbidity in the wastewater. Then, according to HJ 1075-2019 "Determination of Turbidity in Water - Turbidity Meter Method", the turbidity of the separated water was measured using a turbidity meter to measure the magnetic recovery effect of the turbidity. The results are as follows: Hg 2+ Removal rate = 99.991%, water turbidity = 0.35 NTU.

[0071] Example 3: A preparation process for a highly efficient heavy metal ion collector in wastewater, comprising the following steps:

[0072] (1) An iron source (ferric chloride) and aminophenylacetic acid were dissolved in N,N-dimethylformamide to form a precursor solution, wherein the concentration of the iron source was 0.6 mol / L and the concentration of aminophenylacetic acid was 0.5 mol / L. Then, a metal-organic framework material ZIF-7 was added to the precursor solution as a template, and the mass ratio of the template to the iron source was 2:1. The solution was then heated to 70°C in a water bath and held at that temperature for 1.5 h, followed by ultrasonic treatment. Then, it was irradiated with ultraviolet light at a wavelength of 200 nm for 6 h. After completion, the solid product was filtered out and soaked in ethanol with mass fractions of 30%, 50%, 70%, 90%, and 99% for 20 min each. After completion, critical point drying was performed to obtain the template-containing product powder.

[0073] (2) A ZnO layer is deposited on the surface of the template-containing product by atomic layer deposition (ALD). The specific method is as follows: The template-containing product is placed on a rotating dynamic mixing tray in the deposition chamber and rotated at a speed of 10 rpm. Then, diethylzinc (DEZ) and deionized water are sputtered alternately onto the surface of the template-containing product for 0.1 s each time at a temperature of 150 °C. The above-mentioned cross-sputtering process is repeated to form a 5 nm thick ZnO layer rich in hydroxyl groups on the surface of the particles, thus obtaining a secondary modified template material.

[0074] (3) The modified template material is added again to the precursor solution in step (1), and the mass ratio of the modified template material to the iron source in the precursor solution is 2:1. Then, the solution is heated to 70°C in a water bath and held at that temperature for 1.5 hours, followed by ultrasonic treatment. Then, it is irradiated with ultraviolet light at a wavelength of 200 nm for 6 hours. After completion, the solid product is filtered out, heated to 280°C and held for 1 hour for annealing, and then naturally cooled to room temperature. The resulting product is added to 0.5 mol / L citric acid and stirred continuously, with the citric acid being replaced every 30 minutes, until Zn is no longer detectable in the acid solution. 2+ The presence of [a specific ingredient] completes the acid washing process. The resulting product is then sequentially immersed in ethanol at concentrations of 30%, 50%, 70%, 90%, and 99% for 20 minutes each. After this, critical point drying is performed to obtain Fe-MOF powder, such as... Figure 9 As shown.

[0075] (4) Place the Fe-MOF powder in a quartz sample stage, then place it in a reaction chamber, introduce nitrogen as a protective atmosphere, then heat it to 250°C by infrared irradiation and hold it for 1 hour. Then switch the protective atmosphere to an oxygen-containing atmosphere composed of nitrogen and oxygen (oxygen volume fraction of 10%). After completion, raise the temperature to 300°C and continue to hold it for 2 hours. After completion, allow it to cool naturally to room temperature to obtain γ-Fe2O3@MOF powder.

[0076] (5) The γ-Fe2O3@MOF powder and anhydrous ethanol were mixed at a ratio of 1g:300mL and stirred for 10min to form a suspension. Potassium carbonate solution was then added to adjust the pH of the suspension to 8.5. Carbon disulfide (CS2) was then added to the suspension using a constant-pressure dropping funnel at a molar ratio of 2:1 to the γ-Fe2O3@MOF. The mixture was then reacted under ultrasonic treatment for 8 hours. If the pH of the system dropped below 8 during the reaction, potassium carbonate solution was immediately added to ensure the pH remained above 8. After completion, the solid product was separated using an external magnetic field. The solid product was then washed alternately with anhydrous ethanol and deionized water, with each washing agent applied 5 times. Finally, the product was vacuum dried at 75℃ for 9 hours to obtain the final product. Figure 10The trapping agent shown has SEM and TEM images as follows: Figure 11 , Figure 12 As shown.

[0077] Performance testing: 1. The trapping agent prepared in this embodiment was added to Hg at an addition rate of 6.4 mg / L. 2+ In wastewater with an initial mercury concentration of 5.0012 mg / L, the Hg in the wastewater was determined by cold vapor atomic absorption spectrophotometry according to the test method in HJ 597-2011 "Determination of Total Mercury in Water - Cold Vapor Atom Absorption Spectrophotometry". 2+ The remaining amount, and calculate Hg. 2+ Removal rate. 2. A 0.5T magnetic field was used to separate the turbidity in the wastewater. Then, according to HJ 1075-2019 "Determination of Turbidity in Water - Turbidity Meter Method", the turbidity of the separated water was measured using a turbidity meter to measure the magnetic recovery effect of the turbidity. The results are as follows: Hg 2+ Removal rate = 99.994%, water turbidity = 0.47 NTU.

[0078] Example 4: A preparation process for a highly efficient heavy metal ion collector in wastewater, comprising the following steps:

[0079] (1) An iron source (ferric nitrate) and aminophenylacetic acid were dissolved in N,N-dimethylformamide to form a precursor solution, wherein the concentration of the iron source was 0.1 mol / L and the concentration of aminophenylacetic acid was 0.1 mol / L. Then, a metal-organic framework material ZIF-7 was added to the precursor solution as a template, and the mass ratio of the template to the iron source was 1.5:1. The solution was then heated to 80°C in a water bath and held at that temperature for 1 hour, followed by ultrasonic treatment. Then, it was irradiated with ultraviolet light at a wavelength of 240 nm for 6.5 hours. After completion, the solid product was filtered out and then soaked in ethanol with mass fractions of 30%, 50%, 70%, 90%, and 99% for 15 minutes each. After completion, critical point drying was performed to obtain the template-containing product powder.

[0080] (2) The template-containing product powder is added again to the precursor solution in step (1), and the mass ratio of the powder to the iron source in the precursor solution is 1.5:1. Then, it is heated to 80°C in a water bath and held at that temperature for 1 hour. Then, it is irradiated with ultraviolet light at a wavelength of 240 nm for 6.5 hours. After completion, the solid product is filtered out, heated to 250°C and held for 2 hours for annealing, and then naturally cooled to room temperature. The obtained product is added to a 0.3 mol / L acetic acid aqueous solution and stirred continuously, with the acetic acid aqueous solution being replaced every 30 minutes until Zn is not detectable in the acid solution. 2+The presence of [a specific ingredient] completes the acid washing process. The resulting product is then sequentially immersed in ethanol at concentrations of 30%, 50%, 70%, 90%, and 99% for 15 minutes each. After this, critical point drying is performed to obtain Fe-MOF powder, such as... Figure 13 As shown.

[0081] (3) The γ-Fe2O3@MOF powder and anhydrous ethanol were mixed at a ratio of 1g:200mL and stirred for 10min to form a suspension. Sodium carbonate solution was then added to adjust the pH of the suspension to 8.5. Carbon disulfide (CS2) was then added to the suspension using a constant-pressure dropping funnel at a molar ratio of 1.5:1 to the γ-Fe2O3@MOF. The mixture was then reacted under ultrasonic treatment for 6 hours. If the pH of the system dropped below 8 during the reaction, sodium carbonate solution was immediately added to ensure the pH remained above 8. After completion, the solid product was separated using an external magnetic field. The solid product was then washed alternately with anhydrous ethanol and deionized water, with each washing agent being applied 4 times. Finally, the product was vacuum dried at 60℃ for 12 hours to obtain the final product. Figure 14 The trapping agent shown.

[0082] Performance testing: 1. The trapping agent prepared in this embodiment was added to Hg at an addition rate of 5.7 mg / L. 2+ In wastewater with an initial mercury concentration of 5.0012 mg / L, the Hg in the wastewater was determined by cold vapor atomic absorption spectrophotometry according to the test method in HJ 597-2011 "Determination of Total Mercury in Water - Cold Vapor Atom Absorption Spectrophotometry". 2+ The remaining amount, and calculate Hg. 2+ Removal rate. 2. A 0.5T magnetic field was used to separate the turbidity in the wastewater. Then, according to HJ 1075-2019 "Determination of Turbidity in Water - Turbidity Meter Method", the turbidity of the separated water was measured using a turbidity meter to measure the magnetic recovery effect of the turbidity. The results are as follows: Hg 2+ Removal rate = 61.804%, water turbidity = 0.51 NTU.

[0083] Example 5: A preparation process for a highly efficient heavy metal ion collector in wastewater, comprising the following steps:

[0084] (1) The Fe-MOF powder prepared in Example 2 above was placed in a quartz sample stage and then placed in a reaction chamber. It was then electrically heated to 200°C in an air atmosphere and kept at that temperature for 2 hours. After completion, it was naturally cooled to room temperature to obtain γ-Fe2O3@MOF powder.

[0085] (2) The γ-Fe2O3@MOF powder was mixed with isopropanol at a ratio of 1g:150mL and stirred for 10min to form a suspension. Sodium bicarbonate solution was then added to adjust the pH of the suspension to 8. Carbon disulfide (CS2) was then added to the suspension using a constant-pressure dropping funnel at a molar ratio of 1.2:1 to the γ-Fe2O3@MOF. The mixture was then reacted under ultrasonic treatment for 7 hours. If the pH of the system dropped below 8 during the reaction, sodium bicarbonate solution was immediately added to ensure the pH remained above 8. After completion, the solid product was separated using an external magnetic field. The solid product was then washed alternately with anhydrous ethanol and deionized water, with each washing agent applied three times. Finally, the product was vacuum dried at 80℃ for 4 hours to obtain the final product. Figure 15 The trapping agent shown.

[0086] Performance testing: 1. The trapping agent prepared in this embodiment was added to Hg at an addition rate of 6.2 mg / L. 2+ In wastewater with an initial mercury concentration of 5.0012 mg / L, the Hg in the wastewater was determined by cold vapor atomic absorption spectrophotometry according to the test method in HJ 597-2011 "Determination of Total Mercury in Water - Cold Vapor Atom Absorption Spectrophotometry". 2+ The remaining amount, and calculate Hg. 2+ Removal rate. 2. A 0.5T magnetic field was used to separate the turbidity in the wastewater. Then, according to HJ 1075-2019 "Determination of Turbidity in Water - Turbidity Meter Method", the turbidity of the separated water was measured using a turbidity meter to measure the magnetic recovery effect of the turbidity. The results are as follows: Hg 2+ Removal rate = 99.973%, water turbidity = 16.22 NTU.

[0087] Example 6: A preparation process for a highly efficient heavy metal ion collector in wastewater, comprising the following steps:

[0088] The γ-Fe₂O₃@MOF powder prepared in Example 2 was mixed with isopropanol at a ratio of 1 g: 150 mL and stirred for 10 min to form a suspension. Sodium bicarbonate solution was then added to adjust the pH of the suspension to 8. The solid product was then separated using an external magnetic field, and subsequently washed alternately with anhydrous ethanol and deionized water, three times with each washing agent. Finally, the product was vacuum dried at 80 °C for 4 hours to obtain the desired product. Figure 16 The trapping agent shown.

[0089] Performance testing: 1. The trapping agent prepared in this embodiment was added to Hg at an addition rate of 6.2 mg / L. 2+In wastewater with an initial mercury concentration of 5.0012 mg / L, the Hg in the wastewater was determined by cold vapor atomic absorption spectrophotometry according to the test method in HJ 597-2011 "Determination of Total Mercury in Water - Cold Vapor Atom Absorption Spectrophotometry". 2+ The remaining amount, and calculate Hg. 2+ Removal rate. 2. A 0.5T magnetic field was used to separate the turbidity in the wastewater. Then, according to HJ 1075-2019 "Determination of Turbidity in Water - Turbidity Meter Method", the turbidity of the separated water was measured using a turbidity meter to measure the magnetic recovery effect of the turbidity. The results are as follows: Hg 2+ Removal rate = 25.091%, water turbidity = 0.38 NTU.

[0090] Example 7: A preparation process for a highly efficient heavy metal ion collector in wastewater, the same as in Example 3 above, except that the Fe-MOF powder in this example is prepared by the following method:

[0091] Iron source (ferric chloride) and aminophenylacetic acid were dissolved in N,N-dimethylformamide to form a precursor solution, wherein the concentration of the iron source was 0.6 mol / L and the concentration of aminophenylacetic acid was 0.5 mol / L. Then, the secondary modified template material prepared in Example 3 was added to the precursor solution, with a mass ratio of the secondary modified template material to the iron source of 2:1. The solution was then heated to 70°C in a water bath and held at this temperature for 1.5 h, followed by ultrasonic treatment. After completion, the solid product was filtered out and annealed by heating to 280°C for 1 h. The annealed product was then allowed to cool naturally to room temperature. The resulting product was added to 0.5 mol / L citric acid and stirred continuously, with the citric acid being replaced every 30 min, until Zn was no longer detectable in the acid solution. 2+ The presence of [a specific ingredient] completes the acid washing process. The resulting product is then sequentially immersed in ethanol at concentrations of 30%, 50%, 70%, 90%, and 99% for 20 minutes each. Afterward, critical point drying is performed to obtain [the desired product]. Figure 17 The Fe-MOF powder shown, and the collector obtained in this embodiment are as follows: Figure 18 As shown.

[0092] Performance testing: 1. The trapping agent prepared in this embodiment was added to Hg at an addition rate of 6.2 mg / L. 2+ In wastewater with an initial mercury concentration of 5.0012 mg / L, the Hg in the wastewater was determined by cold vapor atomic absorption spectrophotometry according to the test method in HJ 597-2011 "Determination of Total Mercury in Water - Cold Vapor Atom Absorption Spectrophotometry". 2+ The remaining amount, and calculate Hg. 2+Removal rate. 2. A 0.5T magnetic field was used to separate the turbidity in the wastewater. Then, according to HJ 1075-2019 "Determination of Turbidity in Water - Turbidity Meter Method", the turbidity of the separated water was measured using a turbidity meter to measure the magnetic recovery effect of the turbidity. The results are as follows: Hg 2+ Removal rate = 39.707%, water turbidity = 11.75 NTU.

[0093] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A preparation process for a highly efficient heavy metal ion collector in wastewater, characterized in that, Includes the following steps: (1) The Fe-MOF powder was heated by infrared irradiation in a protective atmosphere and kept at a certain temperature. Then, the temperature was increased and kept at a certain temperature after switching to an oxygen-containing atmosphere. After completion, it was naturally cooled to room temperature to obtain γ-Fe2O3@MOF powder. (2) The γ-Fe2O3@MOF powder is dispersed in an alcohol liquid to form a suspension, and then the suspension is adjusted to alkaline, carbon disulfide is added and reacted under ultrasonic treatment; after completion, the solid product is separated, washed and dried to obtain the scavenger grafted with dithiocarbamate groups. In step (1), the Fe-MOF powder is prepared by the following method: (i) Iron source and aminophenylacetic acid are dissolved in N,N-dimethylformamide to form a precursor solution, and then metal-organic framework material ZIF-7 is added and ultrasonically treated under heating conditions; After completion, the product was irradiated with ultraviolet light, and then the solid product was separated and washed to obtain the template-containing product. (ii) A ZnO layer containing hydroxyl groups is deposited on the surface of the template product to obtain a secondary modified template material; (iii) The modified template material is added back into the precursor solution of step (1) and then ultrasonically treated under heating conditions; After completion, the product is irradiated with ultraviolet light, then the solid product is separated and annealed. Finally, the obtained product is acid-washed and then washed to obtain the Fe-MOF powder.

2. The preparation process of the high-efficiency heavy metal ion collector in wastewater according to claim 1, characterized in that, In step (1), the heating temperature is 200~250℃ and the holding time is 1~2h.

3. The preparation process of the high-efficiency heavy metal ion collector in wastewater according to claim 1, characterized in that, In step (1), the volume fraction of oxygen in the oxygen-containing atmosphere is maintained between 5% and 10%.

4. The preparation process of the high-efficiency heavy metal ion collector in wastewater according to claim 1, characterized in that, In step (1), after switching to the oxygen-containing atmosphere, the temperature is raised to 250~300℃ and then kept at that temperature for 2~4 hours.

5. The preparation process of the high-efficiency heavy metal ion collector in wastewater according to claim 1, characterized in that, In step (2), the ratio of γ-Fe2O3@MOF to alcohol liquid is 1g: 150~300mL.

6. The preparation process of the high-efficiency heavy metal ion collector in wastewater according to claim 1, characterized in that, In step (2), the suspension is adjusted to be alkaline by using at least one of sodium carbonate, potassium carbonate, and sodium bicarbonate.

7. The preparation process of the high-efficiency heavy metal ion collector in wastewater according to claim 1, characterized in that, In step (2), the mass ratio of carbon disulfide to γ-Fe2O3@MOF is 1.2~2:

1.

8. The preparation process of the high-efficiency heavy metal ion collector in wastewater according to claim 1, characterized in that, In step (2), the alcohol liquid includes at least one of anhydrous methanol, anhydrous ethanol, and isopropanol.

9. The preparation process of the high-efficiency heavy metal ion collector in wastewater according to claim 1, characterized in that, In step (2), the pH of the system is maintained between 8 and 8.5 during the reaction process.

10. The preparation process of the high-efficiency heavy metal ion collector in wastewater according to claim 1, characterized in that, In step (2), the reaction time is 6-8 hours.

11. The preparation process of the high-efficiency heavy metal ion collector in wastewater according to claim 1, characterized in that, In step (2), the drying temperature is 60~80℃ and the time is 4~12h.

12. The preparation process of the high-efficiency heavy metal ion collector in wastewater according to claim 1, characterized in that, In step (ii), the thickness of the ZnO layer is 5~10nm.

13. The preparation process of the high-efficiency heavy metal ion collector in wastewater according to claim 1, characterized in that, In step (i), the iron source includes at least one of ferric nitrate and ferric chloride.

14. The preparation process of the high-efficiency heavy metal ion collector in wastewater according to claim 1, characterized in that, In step (i), the concentration of the iron source in the precursor solution is 0.1~0.6 mol / L.

15. The preparation process of the high-efficiency heavy metal ion collector in wastewater according to claim 1, characterized in that, In step (i), the concentration of aminophenylacetic acid in the precursor solution is 0.1~0.5 mol / L.

16. The preparation process of the high-efficiency heavy metal ion collector in wastewater according to claim 1, characterized in that, In step (i), the mass ratio of the metal-organic framework material ZIF-7 to the iron source is 1~2:

1.

17. The preparation process of the high-efficiency heavy metal ion collector in wastewater according to claim 1, characterized in that, In step (iii), the mass ratio of the secondary modified template material to the iron source is 1~2:

1.

18. The preparation process of the high-efficiency heavy metal ion collector in wastewater according to claim 1, characterized in that, In steps (i) and (iii), the heating temperature is 60~80℃ and the ultrasonic treatment time is 1~2 hours.

19. The preparation process of the high-efficiency heavy metal ion collector in wastewater according to claim 1, characterized in that, In steps (i) and (iii), the irradiation time is 6 to 8 hours.

20. The preparation process of the high-efficiency heavy metal ion collector in wastewater according to claim 1, characterized in that, In steps (i) and (iii), the wavelength of the ultraviolet light is 200~280nm.

21. The preparation process of the high-efficiency heavy metal ion collector in wastewater according to claim 1, characterized in that, In step (iii), the annealing treatment is performed at a temperature of 240~280℃ for 1~3 hours.

22. The preparation process of the high-efficiency heavy metal ion collector in wastewater according to claim 1, characterized in that, In steps (i) and (iii), the washing method is as follows: the product is soaked in ethanol with a mass fraction of 30%, 50%, 70%, 90%, and 99% in sequence, and then critical point drying is performed to obtain the product.

23. The preparation process of the high-efficiency heavy metal ion collector in wastewater according to claim 1, characterized in that, In step (iii), the acid washing method involves adding the product to an acid solution and stirring, changing the acid solution during the process, until Zn is no longer detectable in the acid solution. 2+ The presence of this element completes the pickling process.

24. The preparation process of the high-efficiency heavy metal ion collector in wastewater according to claim 23, characterized in that, The concentration of the acid solution is 0.1~0.5 mol / L.

25. The preparation process of the high-efficiency heavy metal ion collector in wastewater according to claim 23, characterized in that, The acid solution includes at least one of acetic acid and citric acid.

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