High-efficiency wastewater treatment agent based on molybdenum disulfide nanodefects, its preparation method and application

Abstract

This invention relates to the field of wastewater treatment agent technology, particularly to a nano-defect-based high-efficiency wastewater treatment agent based on molybdenum disulfide, its preparation method, and its application. It involves adjusting the structure of MoS2 by controlling the ratio of precursors to achieve Mo atom-deficient Mo-S atoms, resulting in a Mo-atom-deficient adsorbent. The adsorbent exhibits an overall amorphous, non-crystalline nanostructure. The precursors include soluble ammonium molybdate tetrahydrate and thioacetamide. By adjusting the concentration of the precursors, a reasonable defect design is achieved. This defect type design significantly increases the concentration of Mo stripping defects, exposing more binding S atoms and thus greatly increasing the number of active sites, resulting in excellent adsorption performance and high application value in wastewater treatment.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment agent technology, and in particular to a nano-defect type high-efficiency wastewater treatment agent based on molybdenum disulfide, its preparation method and application. Background Technology

[0002] Mercury is a highly toxic heavy metal pollutant that can cause birth defects, brain damage, and diseases in humans and other species, and has long been a threat to public health and the environment. Mercury is non-biodegradable and can therefore accumulate in organisms, threatening human health through the food chain. Therefore, research on the design and preparation of highly efficient mercury adsorbents has attracted considerable attention from researchers both domestically and internationally.

[0003] Currently, many conventional methods for removing heavy metal ions from wastewater have been developed, such as ion exchange, membrane separation, electrochemical treatment, chemical precipitation, and adsorption. Adsorption, due to its advantages of simple operation, low energy consumption, and high selectivity, has become one of the most promising water treatment technologies. Traditional adsorbents, such as activated carbon, zeolite, and clay, typically suffer from drawbacks such as poor selectivity, low capacity, and weak binding to mercury.

[0004] Molybdenum disulfide, due to its rich sulfur atoms and two-dimensional layered structure, possesses the potential for mercury ion enrichment and separation. CN109231272A discloses a method for stripping molybdenum disulfide, the method comprising the following steps: (1) mixing molybdenum disulfide powder, water and surfactant to obtain a mixed solution; (2) subjecting the mixed solution to ultrasonic stripping treatment to obtain molybdenum disulfide. The surfactant used in this invention has both hydrophilic and hydrophobic groups. The hydrophobic groups can stably bind to molybdenum disulfide, while the hydrophilic groups allow it to be stably dispersed in water. Due to the interaction of the hydrophilic and hydrophobic groups, the molybdenum disulfide powder is emulsified into a colloid, improving its dispersibility in aqueous solution and thus achieving more thorough stripping. The stripped molybdenum disulfide can be stably dispersed in aqueous solution and exhibits good antibacterial properties. The mass concentration of molybdenum disulfide in the suspension is ≥0.089 mg / mL; the antibacterial rate is ≥12% at a mass concentration of 10 mg / L; ≥26% at a mass concentration of 20 mg / L; and ≥70% at a mass concentration of 50 mg / L. The molybdenum disulfide described in this invention has high stability and safety due to the absence of organic residue on its surface, making it suitable for applications in water treatment and biomedicine. However, most sulfur atoms (binding sites) are located inside the MoS2 matrix, thus hindering effective contact between S and Hg, thereby limiting the adsorption capacity of existing MoS2.

[0005] Engineering defects in MoS2 is an effective method to achieve superior adsorption (mercury) performance. However, precisely controlling the defect type remains crucial and challenging. Most reported nanodefect types are sulfur vacancies. For MoS2 used in water treatment to remove heavy metals, sulfur atoms are the main active sites, and the absence of a large number of sulfur atoms is clearly detrimental to achieving significant improvements in adsorption performance. Therefore, rational and controllable defect modulation remains a challenging task. Summary of the Invention

[0006] To address the shortcomings of existing technologies, a high-efficiency wastewater treatment agent based on molybdenum disulfide nanodefects is provided, along with its preparation method and applications. By adjusting the concentration of the precursor, a reasonable defect design is achieved. This defect type design significantly increases the concentration of Mo stripping defects, exposing more S atoms with binding capacity, thereby greatly increasing the number of active sites and giving it excellent adsorption performance. It has high application value in wastewater treatment.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is a nano-defect type high-efficiency sewage treatment agent based on molybdenum disulfide. This agent is an adsorbent with Mo atoms missing by adjusting the structure of MoS2 through the regulation of the precursor ratio. The adsorbent generally has an amorphous nanostructure. The precursor includes soluble ammonium molybdate tetrahydrate and thioacetamide.

[0008] In the above-mentioned molybdenum disulfide-based nano-defect type high-efficiency wastewater treatment agent, the Mo:S ratio in the adsorbent is 1:3.15.

[0009] In the above-mentioned nano-defect-type high-efficiency wastewater treatment agent based on molybdenum disulfide, the molar ratio of ammonium molybdate tetrahydrate to thioacetamide is 1:5-24, and the solid-liquid ratio of the precursor is 1:12-22 ml.

[0010] The aforementioned molybdenum disulfide-based nano-defect type high-efficiency wastewater treatment agent, wherein the adsorbent is effective against Hg. 2+ The maximum adsorption capacity is as high as 3723.3 mg / g.

[0011] The preparation method of the above-mentioned molybdenum disulfide-based nano-defect type high-efficiency wastewater treatment agent includes the following steps:

[0012] (1) Weigh out soluble ammonium molybdate tetrahydrate and thioacetamide in a molar ratio of 1:5-24, add 37.5-40 ml of deionized water, and make a solid-liquid ratio of 1:12-22 ml. Sonicate until completely dissolved.

[0013] (2) Transfer the product obtained in step (1) to a black reactor, with a hydrothermal temperature of 180℃-200℃ and a hydrothermal time of 15-24 hours.

[0014] (3) Transfer the product obtained in step (2) to a centrifuge tube and centrifuge and wash it 3-4 times at 6000-10000 rpm, leaving the precipitate, which is the nano-defect type high-efficiency sewage treatment agent based on molybdenum disulfide.

[0015] The aforementioned molybdenum disulfide-based nano-defect type high-efficiency wastewater treatment agent has a thioacetamide molecular weight of 75.13 g / mol.

[0016] The application of molybdenum disulfide-based nano-defect type high-efficiency wastewater treatment agent is as a wastewater treatment agent, especially for the adsorption of mercury ions.

[0017] In the application of the above-mentioned molybdenum disulfide-based nano-defect type high-efficiency wastewater treatment agent, 10 mg of adsorbent was weighed and placed in 100 mL of mercury ion solution with a concentration in the range of 1 to 500 ppm. The mixture was stirred at 1600 rpm for 24 h at room temperature. The maximum adsorption capacity of the adsorbent reached 3723.3 mg / g, and the removal rate of mercury ions was 99%.

[0018] The beneficial effects of this invention, which relates to a nano-defect-based high-efficiency wastewater treatment agent based on molybdenum disulfide, its preparation method, and its application, are that by adjusting the ratio of the precursors (ammonium molybdate tetrahydrate and thioacetamide), the structure of MoS2 is modified to result in Mo-atom-deficient MoS2. x The original MoS2 had a Mo:S atomic ratio of 1:2. The prepared MV-MoS2 was determined by ICP-OES. x The Mo:S ratio in the sample is 1:3.15, proving that MV-MoS was ultimately obtained. x (x = 3.15). This defect type design significantly increases the concentration of Mo stripping defects, exposing more binding S atoms and thus greatly increasing the number of active sites, resulting in excellent adsorption performance.

[0019] A unique nanoscale MoS2 with molybdenum vacancies (MV-MoS2) structure was obtained using a one-step hydrothermal method. The abundant defects caused by the absence of Mo atoms may lead to crystal cracking, resulting in an overall amorphous amorphous nanostructure. This structure increases the accessible internal surface area, exposing more sulfur atoms with binding effects. Furthermore, the abundant defects can also improve the mass transfer rate and reduce its own specific gravity. Therefore, it is expected that engineered defect structures on the substrate can increase binding sites by forming molybdenum-based defects on the nanosheets, which can significantly improve adsorption performance. MV-MoS2 exhibits Hg... 2+The maximum adsorption capacity is as high as 3723.3 mg / g. In addition, MV-MoS2 exhibits high adsorption capacity for Hg. 2+ It also has high selectivity.

[0020] The preparation method of this invention is easy to operate, the raw materials are readily available and the cost is low, and it has broad application prospects in actual water treatment processes. Attached Figure Description

[0021] Figure 1 The structural characterization diagrams of MV-MoS2 are as follows: a) TEM image of MV-MoS2; b) HRTEM image of the MV-MoS2 substrate, with the inset showing the corresponding SAED pattern; c) XRD pattern and cross-sectional HRTEM image of MV-MoS2; d) Structural model of MV-MoS2, with multiple defects on the substrate and channels caused by defects between layers.

[0022] Figure 2 Scanning electron microscope (SEM) images of the adsorbents prepared in Examples 1-3;

[0023] Figure 3 for Figure 3 Adsorption isotherms of the adsorbents prepared in Examples 1-3;

[0024] Figure 4 The adsorbent prepared in Example 1 has a positive effect on Hg. 2+ Adsorption kinetics; Detailed Implementation

[0025] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0026] The high-efficiency wastewater treatment agent based on molybdenum disulfide nanodefects is an adsorbent with Mo atom deficiency obtained by adjusting the structure of MoS2 through the regulation of the precursor ratio, resulting in the absence of Mo atoms in Mo-S. The adsorbent generally exhibits an amorphous nanostructure, and the precursor includes soluble ammonium molybdate tetrahydrate and thioacetamide.

[0027] In the above-mentioned molybdenum disulfide-based nano-defect type high-efficiency wastewater treatment agent, the Mo:S ratio in the adsorbent is 1:3.15.

[0028] In the above-mentioned nano-defect-type high-efficiency wastewater treatment agent based on molybdenum disulfide, the molar ratio of ammonium molybdate tetrahydrate to thioacetamide is 1:5-24, and the solid-liquid ratio of the precursor is 1:12-22 ml.

[0029] The aforementioned molybdenum disulfide-based nano-defect type high-efficiency wastewater treatment agent, wherein the adsorbent is effective against Hg. 2+ The maximum adsorption capacity is as high as 3723.3 mg / g.

[0030] Example 1

[0031] The preparation method of a molybdenum disulfide-based nano-defect type high-efficiency wastewater treatment agent includes the following steps:

[0032] (1) Weigh out soluble ammonium molybdate tetrahydrate (NH4)6Mo7O at a molar ratio of 1:24. 24 ·4H2O, 1.3287 g (1.075 mmol) and thioacetamide CH3CSNH2 1.803 g (24 mmol), add 37.5 ml of deionized water, the solid-liquid ratio is 1:12 ml, and sonicate until completely dissolved;

[0033] (2) Transfer the product obtained in step (1) to a 50ml black reactor, with a hydrothermal temperature of 180℃ and a hydrothermal time of 15 hours.

[0034] (3) The product obtained in step (2) is transferred to a centrifuge tube and centrifuged and washed three times at 6000 rpm, leaving the precipitate, which is the nano-defect type high-efficiency sewage treatment agent based on molybdenum disulfide.

[0035] The above-mentioned method for preparing molybdenum disulfide / viscose fiber aerogel adsorbent material with nanodefects, wherein the thioacetamide has a molecular weight of 75.13 g / mol.

[0036] The adsorbent prepared in this embodiment has a mercury ion removal rate of 99.9%.

[0037] Example 2

[0038] The parts of this embodiment that are the same as those in Embodiment 1 will not be repeated here. The difference is that the preparation method of the nano-defect type high-efficiency wastewater treatment agent based on molybdenum disulfide includes the following steps:

[0039] (1) Weigh out soluble ammonium molybdate tetrahydrate (NH4)6Mo7O at a molar ratio of 1:16. 24 1.3287 g (1.075 mmol) of 4H2O and 1.202 g (16 mmol) of thioacetamide CH3CSNH2 were added to 38.6 ml of deionized water, with a solid-liquid ratio of 1:14.8 ml, and sonicated until completely dissolved.

[0040] (2) Transfer the product obtained in step (1) to a 50ml black reactor, with a hydrothermal temperature of 190℃ and a hydrothermal time of 18 hours.

[0041] (3) The product obtained in step (2) is transferred to a centrifuge tube and centrifuged and washed three times at 8000 rpm, leaving the precipitate, which is the nano-defect type high-efficiency sewage treatment agent based on molybdenum disulfide.

[0042] The adsorbent prepared in this embodiment has a mercury ion removal rate of 88.6%.

[0043] Example 3

[0044] The parts of this embodiment that are the same as those in Embodiment 1 will not be repeated here. The difference is that the preparation method of the nano-defect type high-efficiency wastewater treatment agent based on molybdenum disulfide includes the following steps:

[0045] (1) Weigh out soluble ammonium molybdate tetrahydrate (NH4)6Mo7O at a molar ratio of 1:5. 24 ·4H2O, 1.3287g (1.075mmol) and thioacetamide CH3CSNH2 0.37565g (5mmol) were added to 40ml of deionized water, with a solid-liquid ratio of 1:22ml, and sonicated until completely dissolved;

[0046] (2) Transfer the product obtained in step (1) to a 50ml black reactor, with a hydrothermal temperature of 200℃ and a hydrothermal time of 24 hours.

[0047] (3) The product obtained in step (2) is transferred to a centrifuge tube and centrifuged and washed 4 times at 10,000 rpm, leaving the precipitate, which is the nano-defect type high-efficiency sewage treatment agent based on molybdenum disulfide.

[0048] The adsorbent prepared in this embodiment has a mercury ion removal rate of 70.38%.

[0049] Example 4

[0050] The application of molybdenum disulfide-based nano-defect type high-efficiency wastewater treatment agent is as a wastewater treatment agent, especially for the adsorption of mercury ions.

[0051] 10 mg of adsorbent was weighed and placed in 100 mL of mercury ion solution with a concentration in the range of 1–500 ppm. The mixture was stirred at 1600 rpm for 24 h at room temperature. The maximum adsorption capacity of the adsorbent reached 3723.3 mg / g. Figure 3 These are adsorption isotherms for three adsorbents, used to test the maximum adsorption capacity of the adsorbent material. Figure 3 It can be clearly seen that the adsorbent has the largest adsorption capacity, reaching 3723.3 mg / g.

[0052] Weigh 10 mg of the adsorbent prepared in Examples 1-3 above and add it to 100 mL of a mercury ion-containing solution with a concentration of 100 ppm. Stir at 1600 rpm for 24 h at room temperature. Samples are taken at different times within 0-30 hours, and the concentration of mercury ions in the samples is determined using ICP-MS. Adsorption kinetics curves of the MV-MoS2 / VFs aerogel are plotted. Figure 4 It is the adsorbent for Hg2+ The adsorption kinetics mainly show that the adsorbent reaches adsorption equilibrium in a very short time, indicating that the adsorbent has a high affinity for Hg. 2+ It has a high adsorption capacity. For example... Figure 4 As shown, when adsorption equilibrium is reached, the prepared adsorbent achieves a mercury ion removal rate of 99%.

[0053] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. Use of a molybdenum disulfide-based nanodefect type high-efficiency sewage adsorbent in mercury ion adsorption, characterized in that, The preparation method of the adsorbent comprises the following steps: (1) soluble ammonium molybdate tetrahydrate and thioacetamide are weighed according to a molar ratio of 1:5-24, deionized water 37.5-40 mL is added, the solid-liquid ratio is 1:12-22 g / mL, and ultrasonic is performed until complete dissolution; (2) the product obtained in step (1) is transferred to a black reactor, the hydrothermal temperature is 180-200 DEG C, and the hydrothermal time is 15-24 hours; (3) the product obtained in step (2) is transferred to a centrifugal tube and centrifuged at 6000-10000 rpm for 3-4 times of washing, and the precipitate is left, which is a nano-defect molybdenum disulfide sewage adsorbent; The sewage adsorbent is an adsorbent with Mo atom loss obtained by adjusting the structure of MoS2 by regulating the ratio of the precursor, and the adsorbent is generally in a non-crystalline amorphous nanostructure.

2. Use according to claim 1, characterized in that: 10 mg of the sewage adsorbent is weighed and placed in a 100 mL mercury ion-containing solution with a concentration of 1-500 ppm, and stirred at a speed of 1600 rpm for 24 h at room temperature.

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