A method for preparing nickel-molybdenum alloy nanoparticles and a method for treating wastewater thereof

Abstract

The present invention discloses a method for preparing nickel-molybdenum alloy nanoparticles and a method for treating wastewater thereof, comprising the following steps: (1) MoNiO x / Preparation of CNT: (2) Preparation of MoNi / CNT nanostructure. The nickel-molybdenum alloy nanoparticles prepared by the method of the present invention have high electrocatalytic performance. After the Mo-Ni alloy is formed, the two elements Ni and Mo produce a synergistic effect, which is beneficial to reduce the oxygen evolution potential and the generation of hydroxyl radicals. At the same time, under high current density electrolysis, Mo has a dissolution effect and can form a porous structure, so that the real surface area of ​​the electrode is increased, and the electrocatalytic effect of the nickel-molybdenum alloy nanoparticles is further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a method for preparing nickel-molybdenum alloy nanoparticles and a method for treating wastewater using the same. Background Art

[0002] With the increasing development of modern industry, the amount of industrial water and wastewater discharge is increasing, and water bodies in countries around the world have been polluted to varying degrees, leading to an increasingly serious global water shortage crisis. In order to greatly alleviate the shortage of water resources, the research on industrial wastewater treatment technology has also received increasing attention.

[0003] Currently, many methods have been developed to treat wastewater, including physical, chemical or biological processes. Although biological treatment is a low-cost technology, biological treatment systems may not be able to continuously meet treatment requirements due to changes in wastewater characteristics, high chemical oxygen demand (COD) concentrations and low biodegradability. Physical and chemical methods, such as ion exchange, adsorption and coagulation, simply transfer pollutants to another phase instead of destroying them. In recent years, electrochemical oxidation methods have attracted much attention and begun to replace traditional processes due to their advantages such as high efficiency, easy operation and environmental compatibility.

[0004] In terms of pollutant degradation, electrochemical oxidation is the process of oxidizing pollutants directly or indirectly by forming highly oxidatively active oxygen (·OH) on the electrode surface. Generally, the electrochemical oxidation process depends on the anode material. Platinum, carbon, boron-doped diamond (BDD) and metal oxides can be used as anode materials. Among them, lead dioxide (PbO 2 ) has been widely studied as an anode for electrochemical oxidation treatment of wastewater, but PbO 2 Electrode instability, Pb 2+ The precipitation will cause secondary pollution. Therefore, the promotion of electrocatalytic wastewater treatment technology is limited by the electrocatalytic oxidation catalyst. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a method for preparing nickel-molybdenum alloy nanoparticles for electrocatalytic oxidation and cracking of wastewater, so as to solve the problems of high cost, poor stability and secondary pollution of hydrogen catalysts through water electrolysis in the prior art.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A method for preparing nickel-molybdenum alloy nanoparticles for electrocatalytic oxidation and cracking of wastewater comprises the following steps:

[0008] (1) MoNiO X Preparation of CNT:

[0009] After mixing carbon tubes with ethylene glycol, Mo(CO) was added 6 and Ni(OAc) 2 The reaction was stirred at 150℃~200℃ for 2~4h, and after the reaction was completed, it was cooled to room temperature and washed several times to obtain the product MoNiO X / CNT; among them, carbon tube, Mo(CO) 6 and Ni(OAc) 2 The mass ratio is 1:(5~10):(5~10);

[0010] (2) Preparation of MoNi / CNT nanostructures:

[0011] MoNiO X / CNT were laid flat in a magnetic boat, and the magnetic boat was placed in a tube furnace for heating. After the air in the tube furnace was exhausted, the magnetic boat was heated under H 2 / Ar atmosphere is heated to 450°C to 550°C and the reaction is maintained for 20min to 1h to obtain the product MoNi / CNT.

[0012] The present invention also provides a method for treating wastewater by electrocatalytic oxidation and cracking of nickel-molybdenum alloy nanoparticles. The nickel-molybdenum alloy nanoparticles are prepared by the preparation method described in the present invention, and the nickel-molybdenum alloy nanoparticles are mixed with ethanol, water and Nafion to form a mixed solution. The mixed solution is applied to the surface of a carbon electrode and then dried. The operation is repeated at least four times. The carbon electrode is used as an anode and a carbon rod is used as a cathode. Sodium sulfate is added to the sewage as a supporting electrolyte, and the anode and the cathode are placed in an electrolytic cell for cracking treatment.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] 1. The nickel-molybdenum alloy nanoparticles prepared by the method of the present invention have high electrocatalytic performance. After the Mo-Ni alloy is formed, the two elements Ni and Mo produce a synergistic effect, which is beneficial to reduce the oxygen evolution potential, thereby improving the oxidative cracking efficiency. At the same time, under high current density electrolysis, Mo has a dissolution effect and can form a porous structure, so that the real surface area of ​​the electrode is increased, and the catalytic effect of the nickel-molybdenum alloy nanoparticles is further improved.

[0015] 2. The present invention utilizes highly oxidized free radicals (·OH) formed on the electrode surface to oxidize organic matter in sewage. The highly oxidized free radicals can collide with organic matter, resulting in the breaking of covalent bonds and reaction with ·OOH. Moreover, as the degradation time increases, the generated compounds further collide with ·OH and generate new intermediates. The new intermediates can eventually be cracked into water and carbon dioxide, thereby achieving the purpose of treating and degrading organic pollutants in water. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is the XRD diagram of the MoNi / CNT nanomaterial of Example 1.

[0017] Figure 2 TEM image of MoNi alloy nanoparticles of Example 1 grown on CNTs.

[0018] Figure 3 Schematic diagram of an H-type electrolyzer for electrocatalytic cracking. DETAILED DESCRIPTION

[0019] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0020] 1. Preparation of Ni-Mo Alloy Nanoparticles

[0021] (1) MoNiO X Preparation of CNT:

[0022] 20 mg of carbon nanotubes were mixed with 60 ml of ethylene glycol and ultrasonicated for 1 h to make them dispersed evenly. Then they were added to a 100 ml round-bottom flask and 150 mg of Mo(CO) was added. 6 and 100 mg of Ni(OAc) 2 , reacted at 190°C with a stirring speed of 1500 r / min for 3 h, cooled to room temperature after the reaction, and washed with ultrapure water for several times to obtain the product MoNiO X / CNT.

[0023] (2) Preparation of MoNi / CNT nanostructures:

[0024] 30 mg of MoNiO X / CNT were laid flat in a magnetic boat, and the magnetic boat was placed in a tube furnace for heating. After the air in the tube furnace was exhausted, the magnetic boat was heated under H 2 / Ar atmosphere and heated to 500 °C and kept reacting for 30 min to obtain the product MoNi / CNT.

[0025] According to the raw material ratios in Table 1, Examples 1 to 5 were prepared using the above method.

[0026] Table 1

[0027] Example <![CDATA[Carbon nanotubes, Mo(CO) 6 and Ni(OAc) 2 mass ratio]]> Reaction temperature (℃) Product appearance 1 1:2.5:5 500 Nanoparticles 2 1:5:5 500 Nanoparticles 3 1:5:5 600 Nanoparticles 4 1:5:7.5 500 Nanoparticles 5 1:5:10 500 Nanoparticles

[0028] 2. A method for treating wastewater using nickel-molybdenum alloy nanoparticles for electrocatalytic oxidation and cracking

[0029] Using Examples 1 to 5 and Comparative Examples 1 to 2, 1 mg of nickel-molybdenum alloy nanoparticles was mixed with 50 μL of ethanol, 190 μL of water and 10 μL of Nafion to form a mixed solution, and ultrasonic treatment was performed for at least 40 min to form a uniform dispersion system. Then 25 μL of the catalyst was dripped onto a 0.5 cm 2 The prepared catalyst film was dried under an infrared lamp and repeated four times. Methylene blue organic wastewater was used as a sample and a small amount of Na 2 SO 4 As supporting electrolyte, the prepared electrode was used as anode and the carbon rod was used as cathode, and the cracking reaction was carried out in an H-type electrolytic cell.

[0030] Taking 0.5 mol / L methylene blue as an example, the degradation effect is shown in Table 2.

[0031] Table 2

[0032]

[0033] Carbon tube, Mo(CO) 6 and Ni(OAc) 2 The mass ratio of 1:5:5, the sample prepared at 600℃, at a current density of 25mA / cm -2 When the electrolysis time is 30 min, the removal rate of methylene blue can reach 89.7% and the Faraday efficiency can reach 85.2%.

[0034] 3. Stability Test

[0035] The stability test of Examples 1 to 5 was carried out, and the current density was set to 25 mA / cm -2 , under the long-term lysis of 20h, the current density basically did not decay, indicating that Examples 1 to 5 have good stability.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the technical solution. Those skilled in the art should understand that those modifications or equivalent substitutions of the technical solution of the present invention that do not depart from the purpose and scope of the technical solution should be included in the scope of the claims of the present invention.

Claims

1. A method for preparing nickel-molybdenum alloy nanoparticles, characterized in that: The steps include: (1) MoNiO X Preparation of CNT: After mixing carbon tubes with ethylene glycol, add Mo(CO)6 and Ni(OAc)2, stir and react at 150℃~200℃ for 2~4h, cool to room temperature after the reaction, wash several times to obtain the product MoNiO X / CNT; wherein the mass ratio of carbon tube, Mo(CO)6 and Ni(OAc)2 is 1:(5-10):(5-10); the mixed carbon tube and ethylene glycol are ultrasonically treated to make them uniformly dispersed; (2) Preparation of MoNi / CNT nanostructures: MoNiO X / CNT are laid flat in a magnetic boat, and the magnetic boat is placed in a tubular furnace for heating. After the air in the tubular furnace is exhausted, the temperature is heated to 450°C to 550°C in a H2 / Ar atmosphere and the reaction is maintained for 20min to 1h to obtain the product MoNi / CNT; In step (1), the mass ratio of carbon tubes to ethylene glycol is 1:(3-5), and in step (2), the volume ratio of H2 to Ar is 1:

10.

2. A method for treating wastewater by electrocatalytic oxidation and cracking of nickel-molybdenum alloy nanoparticles, characterized in that: The nickel-molybdenum alloy nanoparticles are prepared by the preparation method as claimed in claim 1, the nickel-molybdenum alloy nanoparticles are mixed with ethanol, water and Nafion to form a mixed solution, the mixed solution is applied to the surface of the carbon electrode and then dried, the operation is repeated at least four times, the carbon electrode is used as the anode, the carbon rod is used as the cathode, sodium sulfate is added to the sewage as a supporting electrolyte, and the anode and the cathode are placed in an electrolytic cell for cracking treatment; In the mixed solution, the amount of nickel-molybdenum alloy nanoparticles is 2-5 mg / mL; In the mixed solution, the volume ratio of water, ethanol and Nafion is 5:19:1.

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