Method for treating wastewater by ultrasound-activated persulfate with molybdenum disulfide nanoflower

Abstract

In order to solve the above technical problems, the application provides a method for treating wastewater by using molybdenum disulfide nanoflower ultrasonic activated persulfate. The molybdenum disulfide with rich sulfur vacancies can continuously generate electrons in the contact electrocatalysis process, and the part of the electrons can break the O-O bond in the persulfate molecule and produce active oxygen species. The use of the electrons generated by the contact electrocatalysis to activate the PS can increase the ROS production in the system and strengthen the removal efficiency of pollutants. The specific method comprises the following steps: preparing molybdenum disulfide nanoflower; preparing S vacancies on the molybdenum disulfide nanoflower; putting the molybdenum disulfide nanoflower with S vacancies into a reaction container containing SDZ, and performing ultrasonic treatment on the ultrasonic container.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of anhydrous treatment, and more particularly relates to a method for treating wastewater by using molybdenum disulfide nanoflower ultrasonic activated persulfate. BACKGROUND

[0002] The persulfate advanced oxidation has been a research hotspot for pollutant removal. The persulfate needs to be activated by a suitable method to achieve efficient removal of pollutants. The existing PS activation methods include heat / metal catalyst / carbon-based catalyst, but there are generally problems such as low energy conversion rate, easy release of metal ions to cause secondary environmental pollution, and poor stability of the catalyst.

[0003] Organic polymers can produce electrons under the action of ultrasound through the contact process with water, thereby initiating a catalytic reaction. This process is called contact electrocatalysis. The electrons can react with water molecules or dissolved oxygen molecules to produce strong oxidizing active species, thereby achieving the removal of pollutants. It has been proved that the contact electrocatalysis can achieve the degradation of methyl orange, but the removal efficiency is still at a low level compared with other advanced oxidation. Therefore, exploring the application potential of the contact electrocatalysis technology in wastewater treatment technology has become a technical problem to be solved by the person skilled in the art. SUMMARY

[0004] In order to solve the above technical problems, the application provides a method for treating wastewater by using molybdenum disulfide nanoflower ultrasonic activated persulfate. The sulfur vacancy-rich molybdenum disulfide can continuously produce electrons in the contact electrocatalysis process. The electrons can break the O-O bond in the persulfate molecule and produce active oxygen species. The use of the electrons produced by the contact electrocatalysis to activate the PS can increase the ROS production in the system and strengthen the removal efficiency of pollutants.

[0005] The specific method comprises the following steps: preparing molybdenum disulfide nanoflower; preparing S vacancies on the molybdenum disulfide nanoflower; putting the molybdenum disulfide nanoflower with S vacancies and persulfate into a reaction container containing SDZ, and performing ultrasonic treatment on the ultrasonic container.

[0006] In a further technical solution, in the step of preparing molybdenum disulfide nanoflower, Na2MoO4·2H2O and thiourea are dissolved in ultrapure water to form a homogeneous solution. Concentrated HCL is added dropwise to the solution to adjust the pH to be acidic and stirred uniformly. The solution is transferred to an autoclave for heating treatment. The black precipitate generated in the autoclave is filtered and washed several times with ultrapure water and ethanol, and then dried with a freeze dryer to obtain clean molybdenum disulfide nanoflower.

[0007] Further technical solutions, the adding amount of Na2MoO4·2H2O is 0.9g, the adding amount of thiourea is 1.2g, and both are dissolved in 90ml of pure water; adding concentrated HCL to adjust the pH to 1, and stirring for 30 minutes.

[0008] Further technical solutions, in the autoclave, the heating temperature is set to 180 DEG C, and the heating time is 24 hours.

[0009] Further technical solutions, in the step of preparing S vacancies of the molybdenum disulfide nanoflower, the molybdenum disulfide nanoflower is soaked in the H2O2 solution for reaction.

[0010] Further technical solutions, in the step of preparing S vacancies of the molybdenum disulfide nanoflower, the concentration of the H2O2 solution is 0.5-10mol / L, the reaction temperature is 5-35 DEG C, and the reaction time is 10-150 seconds.

[0011] Further technical solutions, in the step of preparing S vacancies of the molybdenum disulfide nanoflower, the concentration of the H2O2 solution is 5mol / L, the reaction temperature is 25 DEG C, and the reaction time is 60 seconds.

[0012] Further technical solutions, the initial concentration of the molybdenum disulfide nanoflower is 250mg / L, the initial concentration of the SDZ is 10mg / L, and the persulfate is PMS.

[0013] Further technical solutions, the reaction container is a 40ml glass bottle.

[0014] Further technical solutions, the ultrasonic power is 110W, the frequency is 40kHz, and the reaction time is 5-60min.

[0015] Beneficial effects: Compared with the prior art, the method has the following advantages:

[0016] The method for treating wastewater by activating persulfate through molybdenum disulfide nanoflower ultrasonic in the application can continuously generate electrons in the contact electrocatalysis process, and the part of the electrons can break the O-O bond in the persulfate molecule and produce reactive oxygen species, so that the production of ROS in the system is increased, and the removal efficiency of pollutants is improved. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 For example 1, the degradation efficiency of the sulfur vacancy-rich MoS2 on the SDZ;

[0018] Figure 2 For example 1, the degradation efficiency of the sulfur vacancy-rich MoS2 on the SDZ; DETAILED DESCRIPTION

[0019] The present application is further described in the following Examples, which do not limit the scope of the application. Unless otherwise indicated, the techniques used in the Examples are conventional techniques well known in the art. Unless otherwise indicated, the reagents, methods, and equipment used in the present application are conventional reagents, methods, and equipment in the art, and there is no specific limitation on their sources, which can be purchased on the market or prepared according to conventional methods well known to those skilled in the art.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The use of the terms "include," "includes" or "including" when used in this specification is used to mean "including, but not limited to." Furthermore, unless otherwise required by context, singular terms shall include pluralities and vice versa. The use herein of "or" means "and / or" unless otherwise indicated.

[0021] The technical solutions of the present application are described below through specific examples. It should be understood that the one or more steps mentioned in the present application do not exclude other methods and steps before and after the combination steps, or other methods and steps can be inserted between these explicitly mentioned steps. It should also be understood that these examples are only used to illustrate the present application and not to limit the scope of the present application. Unless otherwise specified, the numbering of each method step is only for the purpose of identifying each method step, and is not intended to limit the arrangement order of each method or to limit the scope of the implementation of the present application. Changes or adjustments of the relative relationship, without substantial changes in technical content, can also be considered as the scope of implementation of the present application.

[0022] The foregoing description of specific exemplary embodiments of the application has been presented for the purpose of illustration and description. They are not intended to be exhaustive or to limit the application to the precise forms disclosed, and various modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain the principles of the application and its practical application. This enables others skilled in the art to implement and use the application in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the application be defined by the claims and their equivalents.

[0023] Example 1

[0024] A method for treating wastewater by ultrasound-activated persulfate with molybdenum disulfide nanoflower, comprising the following steps:

[0025] (1) Preparation of MoS2NFs, 0.9g Na2MoO4.2H2O and 1.2g thiourea were dissolved in 90ml ultrapure water to form a homogeneous solution. Concentrated HCL was added to the solution to adjust the pH to 1, and after stirring for 30 minutes, the solution was transferred to an autoclave and heated at 180°C for 24h. Finally, the black precipitate produced in the autoclave was washed several times with ultrapure water and ethanol, and then dried with a freeze dryer to obtain clean MoS2NFs for further use.

[0026] (2) Preparation of S vacancies, the sample obtained in step 1 was immersed in a 5mol / L H2O2 solution, and MoS2 was allowed to react with H2O2 at 25°C for different times 60s.

[0027] (3) MoS2NFs prepared by step two were configured to have a concentration of 250mg / L MoS2NFs, an initial concentration of 250mg / L, and 100 microliters of PMS (peroxymonosulfate) were added to the reaction system. The initial concentration of SDZ in the reaction system was 10mg / L, and the reaction system was a 40mL glass bottle. The glass bottle was placed in an ultrasonic cleaner with an ultrasonic power of 110W and a frequency of 40kHz. The reaction time was divided into 5min, 10min, 20min, 30min, 45min, 60min, and the degradation effect of SDZ was determined by sampling. The effect is shown in Figure 1

[0028] Example 2

[0029] (1) Preparation of MoS2NFs, 0.9g Na2MoO4.2H2O and 1.2g thiourea were dissolved in 90ml ultrapure water to form a homogeneous solution. Concentrated HCL was added to the solution to adjust the pH to 1, and after stirring for 30 minutes, the solution was transferred to an autoclave and heated at 180°C for 24h. Finally, the black precipitate produced in the autoclave was washed several times with ultrapure water and ethanol, and then dried with a freeze dryer to obtain clean MoS2NFs for further use.

[0030] (2) Preparation of S vacancies, the sample obtained in step 1 was immersed in a 0.5mol / L H2O2 solution, and MoS2 was allowed to react with H2O2 at 35°C for different times 100s.

[0031] ​(3) The molybdenum disulfide nanoflowers obtained in step 2 were prepared into MoS2NFs with a concentration of 250 mg / L. The initial concentration was 250 mg / L. The prepared MoS2NFs and 100 μL of PMS (persulfate) were added to the reaction system. The initial concentration of SDZ in the reaction system was 10 mg / L. The reaction system was a 40 mL glass bottle. The glass bottle was placed in an ultrasonic cleaner with an ultrasonic power of 110 W and a frequency of 40 kHz. The reaction time was 5 min, 10 min, 20 min, 30 min, 45 min, and 60 min. Samples were taken to determine the degradation effect of SDZ.

[0032] Example 3

[0033] (1) Preparation of molybdenum disulfide nanoflowers: 0.9 g Na₂MoO₄·2H₂O and 1.2 g thiourea were dissolved in 90 ml of ultrapure water to form a homogeneous solution. Concentrated HCl was added dropwise to the solution to adjust the pH to 1. After stirring for 30 minutes, the solution was transferred to an autoclave and heated at 180 °C for 24 h. Finally, the black precipitate produced in the autoclave was washed several times with ultrapure water and ethanol, and then dried using a freeze dryer to obtain clean molybdenum disulfide nanoflowers (MoS₂NFs) for further use.

[0034] (2) Preparation of S vacancy: The sample obtained in step 1 was immersed in 0.5 mol / L H2O2 solution, and MoS2 was allowed to react with H2O2 at 40℃ for different times of 80s.

[0035] (3) The molybdenum disulfide nanoflowers obtained in step 2 were configured into MoS2NFs with a concentration of 250 mg / L and the initial concentration of SDZ was 10 mg / L. The configured MoS2NFs and 100 μL of PMS (persulfate) were added to the reaction system. The initial concentration of SDZ in the reaction system was 10 mg / L. The reaction system was a 40 mL glass bottle. The glass bottle was placed in an ultrasonic cleaner with an ultrasonic power of 110 W and a frequency of 40 kHz. The reaction time was 5 min, 10 min, 20 min, 30 min, 45 min, and 60 min. Samples were taken to determine the degradation effect of SDZ.

[0036] Example 4

[0037] Based on Example 1, the experiment was repeated 6 times. The degradation effect of SDZ was as follows: Figure 2 As shown. From Figure 2 The degradation effect shows that repeated experiments (6 times) can achieve near-complete removal.

[0038] Comparative Example 1

[0039] Different from Example 1, this comparative example only added MoS2NFs with a concentration of 250 mg / L to investigate the degradation efficiency of SDZ with an initial concentration of 10 mg / L. The results showed that there was still about 70% of the pollutants remaining as the degradation reaction proceeded.

[0040] Comparative Example 2

[0041] Different from Example 1, this comparative example only added persulfate with a concentration of 250 mg / L to investigate the degradation efficiency of SDZ with an initial concentration of 10 mg / L. The results showed that there was still about 65% of the pollutants remaining as the degradation reaction proceeded.

[0042] The foregoing description of specific exemplary embodiments of the application has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the application to the precise forms disclosed, and various modifications and variations are possible in light of the above teachings. It is intended that the embodiments be chosen and / or described such that it is or are illustrative and enabling, and that the scope of the application is defined by the claims and their equivalents.

Claims

1. A method for treating wastewater by ultrasound-activated persulfate with molybdenum disulfide nanoflow, characterized in that, The method comprises the following steps: Na2MoO4·2H2O and thiourea are dissolved in ultrapure water to form a homogeneous solution, concentrated HCL is added dropwise to the solution to adjust the pH to be acidic and stirred uniformly, the solution is transferred to an autoclave for heat treatment, the black precipitate generated in the autoclave is washed with ultrapure water and ethanol for several times, and then dried with a freeze dryer to obtain clean molybdenum disulfide nanoflower; the molybdenum disulfide nanoflower is soaked in an H2O2 solution for reaction to prepare S vacancies on the molybdenum disulfide nanoflower; the molybdenum disulfide nanoflower with S vacancies and a persulfate salt are put into a reaction container containing SDZ, and the ultrasonic container is subjected to ultrasonic treatment.

2. The method according to claim 1, wherein the method is characterized by, The addition amount of Na2MoO4·2H2O is 0.9 g, the addition amount of thiourea is 1.2 g, and both are dissolved in 90 ml of pure water; concentrated HCL is added to adjust the pH to 1, and stirred for 30 minutes.

3. The method according to claim 2, wherein the method is characterized by, In the autoclave, the heating temperature is set to 180℃, and the heating time is 24 hours.

4. The method according to claim 1, wherein the method is characterized by, In the step of preparing S vacancies in the molybdenum disulfide nanoflower, the concentration of the H2O2 solution is 0.5-10 mol / L, the reaction temperature is 5-35℃, and the reaction time is 10-150 seconds.

5. The method according to claim 4, wherein the method is characterized by, In the step of preparing S vacancies in the molybdenum disulfide nanoflower, the concentration of the H2O2 solution is 5 mol / L, the reaction temperature is 25℃, and the reaction time is 60 seconds.

6. The method of claim 1, wherein the method is characterized by, The initial concentration of the molybdenum disulfide nanoflower is 250 mg / L, the initial concentration of the SDZ is 10 mg / L, and the persulfate salt is PMS.

7. The method according to claim 1, wherein the method is characterized by, The reaction container is a 40 ml glass bottle.

8. The method of claim 1, wherein the method is characterized by, The ultrasonic power is 110 W, the frequency is 40 kHz, and the reaction time is 5-60 minutes.

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