Method for rapidly removing DMSO (dimethylsulfoxide) in wastewater through ultrasonic wave and Fenton reaction

Abstract

The invention discloses a method for rapidly removing DMSO (dimethylsulfoxide) in wastewater through ultrasonic wave and Fenton reaction. According to the method disclosed by the invention, the removal rate of the DMSO wastewater is greater than 95% within 30 minutes by virtue of sequential synergy of ultrasonic treatment and Fenton oxidation and combination of the magnetic-loaded heterogeneous catalyst, and the catalyst can be recycled for more than 10 times. Compared with a traditional Fenton technology, the dosage of H2O2 is reduced by 50%, and the method has a wide application prospect in DMSO wastewater treatment.

Description

Technical Field

[0001] The present invention belongs to the field of dimethyl sulfoxide wastewater treatment, and relates to a method for rapidly removing DMSO in wastewater by ultrasonic wave synergistic Fenton reaction. Background Art

[0002] Dimethyl sulfoxide (DMSO), as a sulfur-containing pollutant, can be discharged into the environment through industrial wastewater, causing pollution to natural water sources. In addition, it is a very hygroscopic liquid, colorless, aprotic, highly polar, and soluble in water, ethanol, acetone, ether, benzene, and chloroform. Research shows that when the concentration of DMSO is higher than 32300mg.L -1 、24600mg.L -1 and 400mg.L -1 it will be harmful to fish, aquatic invertebrates and aquatic plants. Therefore, in order to protect the health of humans and the environment, the wastewater treatment of DMSO is necessary.

[0003] The Fenton process is one of the most popular and cheapest types of advanced oxidation processes (AOPs) at present, and has attracted more and more attention in the treatment of wastewater containing DMSO. The Fenton process has the advantages of short reaction time, can operate at different environmental temperatures and pressures, low mass transfer limitation, low energy consumption, mineralization of organic pollutants and conversion into non-toxic compounds (such as carbon dioxide, water, inorganic salts), and high efficiency. However, it is found that the traditional Fenton method has low effective utilization rate of H2O2, and problems such as iron sludge pollution and incomplete degradation of organic matter often occur during the reaction process, which limits the practical application of the Fenton system. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for rapidly removing DMSO in wastewater by ultrasonic wave synergistic Fenton reaction. In order to improve the oxidation efficiency of H2O2, this method activates H2O2 by introducing ultrasonic waves, and uses Fe3O4@nitrogen-doped carbon nanotubes (Fe3O4@N-CNTs) as a heterogeneous catalyst, which has both high catalytic activity and magnetic separation characteristics, and improves the removal effect of DMSO.

[0005] The technical solution for realizing the purpose of the present invention is as follows:

[0006] A method for rapidly removing DMSO in wastewater by ultrasonic wave synergistic Fenton reaction, comprising the following steps:

[0007] (1) Synthesis of Fe3O4 nanoparticles: Dissolve FeCl3·6H2O in ethylene glycol, then add urea, stir until evenly mixed, and perform a solvothermal reaction at 200-220°C for 12-24 hours to obtain Fe2O4 nanoparticles;

[0008] (2) Nitrogen-doped carbon layer coating: Add glucose to the reaction system in step (1) according to the mass ratio of FeCl3 to glucose of 1:0.5 - 1, and continue the solvothermal reaction at 180 - 200 °C for 6 - 8 hours. After the reaction, centrifuge to separate the solid, wash and dry to obtain the Fe3O4@carbon precursor;

[0009] (3) High-temperature calcination and nitrogen doping: In an inert atmosphere, keep the Fe3O4@carbon precursor at 600 - 800 °C for 2 - 4 hours, then cool naturally and grind to obtain the Fe3O4@N-CNTs composite;

[0010] (4) Add H2O2 and the Fe3O4@N-CNTs composite to the wastewater containing DMSO, and react under ultrasonic conditions to achieve the removal of DMSO.

[0011] Preferably, in step (1), the molar ratio of FeCl3·6H2O to urea is 1:2 - 4.

[0012] Preferably, in step (1), the concentration of FeCl3·6H2O in ethylene glycol is 0.017 mol / mL.

[0013] Preferably, in step (2), the washing method is to wash 3 times with ethanol and water respectively; the drying temperature is 60 ± 5 °C.

[0014] Preferably, in step (3), the inert atmosphere is N2 or Ar, and the heating rate is 2 - 5 °C / min.

[0015] Preferably, in step (4), the concentration of H2O2 is 200 - 300 mmol / L.

[0016] Preferably, in step (4), the addition amount of the Fe3O4@N-CNTs composite is 1 - 3 g / L.

[0017] Preferably, in step (4), the ultrasonic power is 80 - 240 W, the ultrasonic frequency is 40 - 100 KHz, and the ultrasonic temperature is 40 - 80 °C.

[0018] Preferably, in step (4), the reaction time is 30 - 120 min.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] (1) Ultrasonic cavitation enhances mass transfer: The microjet generated by the collapse of cavitation bubbles promotes the desorption of pollutants on the catalyst surface and prevents the passivation of active sites;

[0021] (2) Free radical chain reaction: The H generated by ultrasound + and Fe in the Fenton reagent 2+The co-catalytic decomposition of H2O2 can increase the generation rate of ·OH by 2-3 times;

[0022] (3) Catalyst regeneration: After magnetic recovery, Fe3O4@N-CNTs can be reused more than 10 times through ultrasonic cleaning (soaking in 0.1% dilute hydrochloric acid), and the activity retention rate is >90%;

[0023] (4) Through the sequential synergy of ultrasonic treatment and Fenton oxidation, combined with the magnetic Fe3O4@N-CNTs composite material as a heterogeneous catalyst, it shows high catalytic activity and magnetic separation characteristics in the removal of DMSO wastewater. The removal rate of DMSO wastewater can reach >95% within 30 minutes, and the catalyst can be recycled more than 10 times; compared with the traditional Fenton technology, the dosage of H2O2 is reduced by 50%, showing broad application prospects in the treatment of DMSO wastewater. Specific embodiments

[0024] The present invention will be further described in detail below with specific embodiments.

[0025] Example 1

[0026] 1. Preparation of Fe3O4@N-CNTs composite material:

[0027] (1) Dissolve 1.0 mol of FeCl3·6H2O in 60 mL of ethylene glycol and stir until transparent. Add 3 mol of urea and stir for 30 minutes. Transfer to a high-pressure reactor and react at 220 °C for 18 hours. According to the mass ratio of FeCl3:glucose = 1:0.5, add glucose to the above reaction system and disperse it evenly by ultrasonic wave. React at 200 °C for 6 hours to form Fe3O4@carbon precursor. Centrifuge and wash 3 times with ethanol and water respectively, and dry in vacuum at 60 °C. Then, in an inert atmosphere, heat up to 800 °C at a rate of 3 °C / min and hold for 3 hours. After natural cooling, grind to obtain Fe3O4@N-CNTs composite material.

[0028] 2. Removal of DMSO:

[0029] Weigh a certain amount of DMSO and add it to a 500 mL volumetric flask, add distilled water to the scale to prepare a 178.6 mmol / L DMSO solution. Take 100 mL of DMSO solution and add it to a glass reactor, add 267.9 mmol / L of H2O2 and 2.5 g / L of Fe3O4@N-CNTs composite material, and place it in an ultrasonic cleaner for reaction. The liquid level in the glass reactor is lower than that in the ultrasonic cleaner. The ultrasonic power is 80 W, the ultrasonic frequency is 40 KHz, the ultrasonic temperature is 40 °C, and the reaction time is 30 min. Finally, the removal rate of dimethyl sulfoxide is measured to be 95%.

[0030] Example 2

[0031] This example is basically the same as Example 1, except that the ultrasonic reaction time used in the removal process of DMSO is 60 min. The removal rate of dimethyl sulfoxide measured finally is 97%.

[0032] Example 3

[0033] This example is basically the same as Example 2, except that the ultrasonic temperature used in the removal process of DMSO is 50 °C, and the removal rate of dimethyl sulfoxide measured is 99%.

[0034] Comparative Example 1

[0035] The difference between this comparative example and Example 1 is that Fe3O4@N-CNTs composite material is not added in the removal process of DMSO. Specifically:

[0036] Weigh a certain amount of DMSO and add it to a 500 mL volumetric flask, then add distilled water to the scale line to prepare a 178.6 mmol / L DMSO solution. Take 100 mL of the DMSO solution and add it to a glass reactor, then add 267.9 mmol / L of H2O2, and place it in an ultrasonic cleaner for reaction. The liquid level in the glass reactor is lower than the liquid level in the ultrasonic cleaner, and the reaction time is 30 min. In step (4), the ultrasonic power is 80 W, the ultrasonic frequency is 40 KHz, and the ultrasonic temperature is 40 °C. The removal rate of dimethyl sulfoxide measured finally is 38%.

[0037] Comparative Example 2

[0038] The difference between this comparative example and Example 1 is that ultrasound is not used in the removal process of DMSO. Specifically:

[0039] Weigh a certain amount of DMSO and add it to a 500 mL volumetric flask, then add distilled water to the scale line to prepare a 178.6 mmol / L DMSO solution. Take 100 mL of the DMSO solution and add it to a glass reactor, then add 267.9 mmol / L of H2O2 and 2.5 g / L of Fe3O4@N-CNTs composite material, and the reaction time is 30 min. The removal rate of dimethyl sulfoxide measured finally is 87%.

[0040] Comparative Example 3

[0041] The difference between this comparative example and Example 1 is that ultrasound is not used in the removal process of DMSO, and the addition amount of H2O2 is increased. Specifically:

[0042] Weigh a certain amount of DMSO and add it to a 500 mL volumetric flask. Add distilled water to the scale to prepare a 178.6 mmol / L DMSO solution. Take 100 mL of the DMSO solution and add it to a glass reactor. Add 535.8 mmol / L of H2O2 and 2.5 g / L of Fe3O4@N-CNTs composite material, and the reaction time is 30 min. Finally, the removal rate of dimethyl sulfoxide is measured to be 92%.

[0043] Comparative Example 4

[0044] The difference between this comparative example and Example 1 is that the Fe3O4@N-CNTs composite material is replaced with Fe3O4@CNTs composite material. Specifically:

[0045] 1. Preparation of Fe3O4@CNTs composite material:

[0046] (1) Dissolve 1.0 mol of FeCl3·6H2O in 60 mL of ethylene glycol, stir until transparent, and then transfer it to a high-pressure reactor and react at 220 °C for 18 hours. According to the mass ratio of FeCl3:glucose = 1:0.5, add glucose to the above reaction system and disperse it evenly by ultrasonic wave. React at 200 °C for 6 hours to form Fe3O4@carbon precursor. Centrifuge and separate, wash 3 times with ethanol and water respectively, and dry in vacuum at 60 °C. Then, in an inert atmosphere, heat it to 800 °C at a rate of 3 °C / min and keep it warm for 3 hours. After natural cooling, grind it to obtain Fe3O4@CNTs composite material.

[0047] 2. Removal of DMSO:

[0048] Weigh a certain amount of DMSO and add it to a 500 mL volumetric flask. Add distilled water to the scale to prepare a 178.6 mmol / L DMSO solution. Take 100 mL of the DMSO solution and add it to a glass reactor. Add 267.9 mmol / L of H2O2 and 2.5 g / L of Fe3O4@CNTs composite material, and place it in an ultrasonic cleaner for reaction. The liquid level in the glass reactor is lower than the liquid level in the ultrasonic cleaner. The ultrasonic power is 80 W, the ultrasonic frequency is 40 KHz, the ultrasonic temperature is 40 °C, and the reaction time is 30 min. Finally, the removal rate of dimethyl sulfoxide is measured to be 90%.

Claims

1. A method for rapidly removing DMSO in wastewater by ultrasonic wave synergistic Fenton reaction, characterized in that, It includes the following steps: (1) Synthesis of Fe3O4 nanoparticles: Dissolve FeCl3·6H2O in ethylene glycol, then add urea, stir until evenly mixed, and carry out solvothermal reaction at 200 - 220 °C for 12 - 24 hours to obtain Fe3O4 nanoparticles; (2) Coating with nitrogen-doped carbon layer: Add glucose to the reaction system in step (1) according to the mass ratio of FeCl2 to glucose of 1:0.5 - 1, and continue solvothermal reaction at 180 - 200 °C for 6 - 8 hours. After the reaction ends, centrifuge to separate the solid, wash and dry to obtain Fe3O4@carbon precursor; (3) High-temperature calcination and nitrogen doping: In an inert atmosphere, keep the Fe3O4@carbon precursor at 600 - 800 °C for 2 - 4 hours, then cool naturally and grind to obtain Fe3O4@N-CNTs composite; (4) Add H2O2 and Fe3O4@N-CNTs composite to the wastewater containing DMSO, and carry out the reaction under ultrasonic conditions to achieve the removal of DMSO.

2. The method according to claim 1, wherein In step (1), the molar ratio of FeCl3·6H2O to urea is 1:2 - 4.

3. The method according to claim 1, characterized in that, In step (1), the concentration of FeCl2·6H2O in ethylene glycol is 0.017 mol / mL.

4. The method according to claim 1, wherein In step (2), the washing method is to wash 3 times with ethanol and water respectively; the drying temperature is 60 ± 5 °C.

5. The method according to claim 1, wherein In step (3), the inert atmosphere is N2 or Ar, and the heating rate is 2 - 5 °C / min.

6. The method according to claim 1, wherein In step (4), the concentration of H2O2 is 200 - 300 mmol / L.

7. The method according to claim 1, characterized in that, In step (4), the addition amount of Fe3O4@N-CNTs composite is 1 - 3 g / L.

8. The method according to claim 1, wherein In step (4), the ultrasonic power is 80 - 240 W, the ultrasonic frequency is 40 - 100 KHz, and the ultrasonic temperature is 40 - 80 °C.

9. The method according to claim 1, characterized in that, In step (4), the reaction time is 30 - 120 min.