Preparation method of bimetallic electro-Fenton catalyst

Abstract

The invention relates to a preparation method of a bimetallic electro-Fenton catalyst, which comprises the following steps: putting tourmaline powder, ferric salt, cerium salt or other rare earth metal salts and nitric acid into distilled water, and uniformly mixing according to the mass part ratio of the tourmaline powder to the ferric salt to the cerium salt or other rare earth metal salts to the nitric acid to the distilled water of (5-50): (5-30): (1-30): (10-20): (100-200). The preparation method comprises the following steps: uniformly mixing the raw materials, standing for 1-5 hours, carrying out suction filtration to obtain an insoluble substance in a system, putting the insoluble substance into a crucible, covering the crucible, putting the crucible into a box-type resistance furnace, heating to 350-700 DEG C, keeping the temperature for 8-24 hours, finally cooling to room temperature, and taking out the powder to obtain the product. When the obtained product is used for electro-Fenton degradation of secnidazole, the COD removal rate can reach 89.8%.

Description

Technical Field

[0001] The present invention belongs to the technical field of Fenton, and particularly relates to a preparation method of a bimetallic electro-Fenton catalyst. Background Art

[0002] In recent years, the production scale of antibiotics in China has developed rapidly and has already become a major producer of antibiotic drugs. There are more than 500 domestic antibiotic pharmaceutical enterprises, producing more than a hundred kinds of antibiotic drugs. From the production process of antibiotics and the characteristics of the products themselves, it can be seen that antibiotic wastewater mainly comes from the remaining waste liquid, by-products and residual materials in the production process. It has the characteristics of complex composition, high biological toxicity and difficult degradation, and belongs to one of the wastewaters with high treatment cost and great treatment difficulty.

[0003] The electro-Fenton method uses electrochemistry to generate Fe 2+ and H 2 O 2 as a continuous source of Fenton reagent. Once generated, the two immediately react to generate highly active hydroxyl radicals, which degrade organic matter, and the treatment efficiency is high and the effect is obvious. The electro-Fenton system overcomes the problem of the traditional Fenton method that requires continuous addition of H 2 O 2 , reducing the risk generated during the transportation of H 2 O 2 . However, its anode uses an iron plate, and the ferrous ions generated after energization will increase the pH value of the system as the reaction proceeds, causing irreversible salinization crystallization of the electrode, reducing the content of Fe element in the system, and ultimately resulting in a decrease in degradation efficiency or even inactivation. The electro-Fenton-like process mainly uses a catalyst to load iron elements, and the Fenton reaction occurs on the surface of the catalyst to recycle the iron elements in the form of Fe 2+ / Fe 3+ , which can effectively reduce the problem of iron salt crystallization and also reduce the requirement for the pH value of the Fenton system. In addition, research shows that in addition to iron elements, other multivalent metal elements such as Cu 2+ / Cu + , Ce 4+ / Ce 3+ etc. can also form a Fenton oxidation system and be applied to the Fenton oxidation technology. However, the main bottleneck restricting the development of the Fenton-like technology at present is that the efficiency of the Fenton-like catalyst in the single-metal element system is relatively low and the performance is poor, still waiting to be further improved.

[0004] Tourmaline is a kind of natural ore with good adsorption ability for metal elements. It can be used as a catalyst for loading Fe element, Ce element (or other rare earth metal elements) in a heterogeneous electro-Fenton system. Using tourmaline as the catalyst in the electro-Fenton system can improve the catalytic efficiency of the electro-Fenton system, enhance the catalytic effect, and at the same time reduce the degree of salt crystallization, enabling it to have high degradation ability for a long time. The equations of the Fenton reaction and the mutual reaction generated by iron and cerium elements in the specific catalytic process are as follows:

[0005] Summary of the Invention

[0006] The object of the present invention is to provide a preparation method of a bimetallic electro-Fenton-like catalyst aiming at the defects of the above-mentioned single-metal-element electro-Fenton catalyst in the field of Fenton technology. The multi-metal tourmaline catalyst prepared by the present invention has good catalytic performance, a simple preparation process, can effectively reduce the generation of anode mud, has a long service life, and a good catalytic effect.

[0007] The preparation method of a bimetallic electro-Fenton-like catalyst of the present invention is realized through the following technical solutions. It includes the following steps:

[0008] Put tourmaline powder, iron salt, cerium salt or other rare earth metal salts, and nitric acid into distilled water and mix evenly. Among them, by mass fraction, the ratio of tourmaline powder, iron salt, cerium salt or other rare earth metal salts, nitric acid and distilled water is 5-50:5-30:1-30:10-20:100-200.

[0009] After mixing evenly, let it stand for 1-5 h, and then obtain the insoluble matter in the system by suction filtration. Put the insoluble matter into a crucible, cover it, and then put it into a box-type resistance furnace and heat it to 350-700 °C and keep it for 8-24 h. Finally, cool it down to room temperature and take out the powder to obtain the product of the present invention.

[0010] In the above technical solution, the preparation method of the tourmaline powder is to put tourmaline raw materials into the ball milling tank of a high-energy planetary ball mill and mill for 30 min-180 min. The ball milling medium is 5-10 zirconia balls with a diameter of 3-10 mm. After taking it out, it is sieved through a 400-10000 mesh sieve to obtain tourmaline powder.

[0011] In the above technical solution, the size of the tourmaline powder is 1000-10000 mesh. The iron salt is limited to ferric nitrate or ferric chloride of analytical pure grade. The cerium salt is limited to cerium nitrate or cerium chloride of analytical pure grade. Other rare earth metal salts are limited to rare earth metal nitrates or rare earth metal chloride salts. The concentration of nitric acid is 50-63 wt%.

[0012] In the above technical solution, mechanical stirring is carried out for 1 to 3 hours at a rotation speed of 200 to 600 r / min, and ultrasonic stirring is carried out simultaneously until the mixture is evenly mixed.

[0013] The beneficial effects of the present invention are as follows: The present invention provides a preparation method of a bimetallic electro-Fenton catalyst. The raw materials used in this method are widely sourced, low in price, simple in preparation method, high in iron element content, good in the effect of catalytic degradation of antibiotic wastewater, can effectively prevent the generation of anode mud during the reaction process, and have a long service life. Description of the Drawings

[0014] Figure 1 It is a micrograph of the bimetallic electro-Fenton catalyst prepared in Example 1;

[0015] Figure 2 It is an elemental content diagram of the bimetallic electro-Fenton catalyst prepared in Example 1. Detailed Description of the Invention

[0016] The following examples are used to describe the present invention in more detail:

[0017] Example 1

[0018] 1. Preparation of Fe-Ce bimetallic electro-Fenton catalyst

[0019] (1) Take 100 g of tourmaline raw material and put it into a high-energy planetary ball mill, and at the same time put 5 zirconia balls with a diameter of 3 mm and 5 zirconia balls with a diameter of 5 mm. After grinding for 150 minutes, take it out and pass through a 10,000-mesh sieve to obtain 10,000-mesh tourmaline powder for standby;

[0020] (2) Take 35 g of 10,000-mesh tourmaline, 25 g of ferric nitrate, 15 g of cerium nitrate, 15 g of 63% wt nitric acid, and 150 g of distilled water. Use mechanical stirring, set the rotation speed at 400 r / min, stir for 2 hours and accompany with ultrasonic until the mixture is evenly stirred. After standing for 4 hours, filter to obtain the black powder on the filter paper;

[0021] (3) Put the above-obtained powder into a box-type resistance furnace, heat it to 550 °C and keep it for 20 hours, and finally cool it to room temperature to obtain the Fe-Ce bimetallic electro-Fenton catalyst

[0022] The partial SEM image of the prepared Fe-Ce bimetallic electro-Fenton catalyst is shown in the appendix Figure 1 The elemental content of it is shown in the appendix Figure 2 , Figure 1 As can be seen from, the surface of the tourmaline is in a gully shape with connected pore structures, so it has a large specific surface area and has the characteristics of a catalyst. Figure 2 As can be seen from, it mainly contains iron and cerium elements, which is beneficial to the Fenton reaction.

[0023] 2. Performance Test of Fe-Ce Bimetallic Electro-Fenton Catalyst

[0024] Take 100 mL of 50 mg / L secnidazole aqueous solution to simulate industrial wastewater, add 15 g of the above-prepared Fe-Ce bimetallic electro-Fenton catalyst, use an IrO 2 -RuO 2 electrode with dimensions of 2 cm * 5 cm * 2 mm as the anode, use a graphite felt with dimensions of 2 cm * 5 cm * 2 mm as the cathode, and apply a current density of 30 mA / cm 2 using an electrochemical workstation, and the degradation time is 90 min.

[0025] Its beneficial effect is that the removal rate of COD (chemical oxygen demand) after degradation can reach 89.8%. Repeat the above degradation experiment 10 times, and the COD removal rate in the 10th time can still reach 84.2%.

[0026] Among them, the tourmaline raw material was purchased from Jingwei Minerals Processing Factory Co., Ltd., the manufacturers of nitric acid, ferric nitrate, and cerium nitrate are Yongfei Chemical Reagent Co., Ltd., the manufacturer of secnidazole is Shanghai Aladdin Biochemical Technology Co., Ltd., the model of the electrochemical workstation is Shanghai Chenhua CHI660D, and the model of the high-energy planetary ball mill is Youbei UBE-V0.4L.

[0027] Example 2

[0028] Other steps are the same as those in Example 1, except that the preparation method of the Fe-Ce bimetallic electro-Fenton catalyst is specifically as follows:

[0029] (1) Take 100 g of tourmaline raw material and put it into a high-energy planetary ball mill, and at the same time put 5 zirconia balls with a diameter of 10 mm. After grinding for 30 min, take it out and pass through a 1000-mesh sieve to obtain 1000-mesh tourmaline powder for standby;

[0030] (2) Take 5 g of 1000-mesh tourmaline, 5 g of ferric nitrate, 1 g of cerium nitrate, 10 g of 50 wt% nitric acid, and 200 g of distilled water. Use mechanical stirring, set the rotation speed at 200 r / min, stir for 1 h and accompany with ultrasonic until evenly stirred. After standing for 1 h, filter to obtain the black powder on the filter paper;

[0031] (3) Put the above-obtained powder into a box-type resistance furnace, heat it to 350 °C and keep it for 8 h, and finally cool it to room temperature to obtain the iron-cerium tourmaline catalyst

[0032] The effect is that under the same performance test conditions as in Example 1, the COD removal rate of secnidazole after degradation can reach 56.7%,

[0033] Example 3

[0034] Other steps are the same as those in Example 1, except that the preparation method of the Fe-Ce bimetallic electro-Fenton catalyst is specifically as follows:

[0035] (1) Take 100 g of tourmaline raw materials and put them into a high-energy planetary ball mill, and at the same time put 3 zirconia balls with a diameter of 3 mm and 4 zirconia balls with a diameter of 5 mm. After grinding for 180 min, take them out and pass through a 7500-mesh sieve to obtain 7500-mesh tourmaline powder for standby;

[0036] (2) Take 50 g of 7500-mesh tourmaline, 30 g of ferric nitrate, 30 g of cerium nitrate, 20 g of 55 wt% nitric acid, and 100 g of distilled water. Use mechanical stirring, set the rotation speed at 200 r / min, stir for 3 h and accompany with ultrasonic waves until evenly stirred. After standing for 5 h, filter to obtain the black powder on the filter paper;

[0037] (3) Put the obtained powder into a box-type resistance furnace, heat it to 700 °C and keep it for 24 h, and finally cool it to room temperature to obtain the iron-cerium tourmaline catalyst

[0038] The effect is: Under the same performance test conditions as in Example 1, the COD removal rate of secnidazole after degradation can reach 68.4%;

[0039] Example 4

[0040] Other steps are the same as those in Example 1, except that ferric chloride is used instead of ferric nitrate in the preparation method of the Fe-Ce bimetallic tourmaline catalyst.

[0041] The effect is: Under the same performance test conditions as in Example 1, the COD removal rate of secnidazole after degradation can reach 84.7%.

[0042] Example 5

[0043] Other steps are the same as those in Example 1, except that cerium chloride is used instead of cerium nitrate in the preparation method of the Fe-Ce bimetallic tourmaline catalyst.

[0044] The effect is: Under the same performance test conditions as in Example 1, the COD removal rate of secnidazole after degradation can reach 83.8%.

[0045] Example 6

[0046] Other steps are the same as those in Example 1, except that lanthanum nitrate is used instead of cerium nitrate in the preparation method of the bimetallic tourmaline catalyst.

[0047] The effect is: Under the same performance test conditions as in Example 1, the COD removal rate of secnidazole after degradation can reach 78.8%.

[0048] Example 7

[0049] Other steps are the same as those in Example 1, except that cerium nitrate is replaced by lanthanum chloride in the preparation method of the bimetallic tourmaline catalyst.

[0050] The result is that under the same performance test conditions as in Example 1, the COD removal rate of secnidazole after degradation can reach 79.6%.

[0051] Example 8

[0052] Other steps are the same as those in Example 1, except that cerium nitrate is not added in the preparation method of the catalyst.

[0053] The result is that under the same performance test conditions as in Example 1, the COD removal rate of secnidazole after degradation can reach 47.6%.

[0054] Example 9

[0055] Other steps are the same as those in Example 1, except that ferric nitrate is not added in the preparation method of the catalyst.

[0056] The result is that under the same performance test conditions as in Example 1, the COD removal rate of secnidazole after degradation can reach 39.8%.

[0057] Combined with Example 1, Example 8 and Example 9, it can be seen that the catalytic performance of the iron-cerium bimetallic catalyst is significantly higher than that of the catalyst without adding iron or cerium. Combined with Example 1-7 and Example 8-9, it can be seen that the catalytic performance of the bimetallic catalyst is higher than that of the monometallic catalyst. The above results are due to the mutual reaction of the iron and rare earth element bimetallic catalyst, which plays a synergistic role to accelerate the circulation of iron elements on the surface of the catalyst, accelerate the Fenton reaction rate, generate more hydroxyl radicals, and increase the COD degradation rate of antibiotics.

[0058] The present invention provides a preparation method of a bimetallic tourmaline catalyst. The catalyst prepared by this method has a simple production process, low cost, excellent performance, and broad development prospects in the field of electro-Fenton degradation of wastewater.

[0059] The above embodiments are only explanations of the present application, not limitations of the present application. Those skilled in the art can make modifications to the embodiments of the present application without creative contributions after reading this specification, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

[0060] Matters not covered in the present invention are well-known technologies.

Claims

1. A method for preparing a bimetallic electro-Fenton catalyst, characterized in that: The following steps are involved: Put tourmaline powder, iron salt, cerium salt or other rare earth metal salt, and nitric acid into distilled water and mix them evenly, wherein the ratio of tourmaline powder, iron salt, cerium salt or other rare earth metal salt, nitric acid and distilled water is 5-50:5-30:1-30:10-20:100-200 by mass; After being mixed evenly, the mixture is allowed to stand for 1 to 5 hours, and then the insoluble matter in the system is obtained by suction filtration. The insoluble matter is placed in a crucible, covered, and placed in a box-type resistance furnace, heated to 350 to 700° C. and maintained for 8 to 24 hours, and finally cooled to room temperature, and the powder is taken out to obtain the product of the present invention; In the above technical scheme, the tourmaline powder preparation method is to put the tourmaline raw material into the ball mill of the high-energy planetary ball mill for 30min to 180min, the ball milling medium is 5 to 10 zirconia balls of 3 to 10mm, and then take it out and pass it through a 400 to 10000 mesh sieve to obtain the tourmaline powder; In the above technical solution, the tourmaline powder has a size of 1000-10000 mesh, the iron salt is limited to analytically pure iron nitrate or iron chloride, the cerium salt is limited to analytically pure cerium nitrate or cerium chloride, other rare earth metal salts are limited to rare earth metal nitrates or rare earth metal chlorides, and the nitric acid concentration is 50-63wt%; In the above technical solution, mechanical stirring is performed for 1 to 3 hours at a rotation speed of 200 to 600 r / min, accompanied by ultrasonic stirring until the mixture is uniform.

2. The method for preparing a bimetallic electro-Fenton catalyst according to claim 1, characterized in that: Contains five ingredients: tourmaline powder, iron salt, rare earth metal salt, nitric acid and distilled water.

3. The method for preparing a bimetallic electro-Fenton catalyst according to claim 1, characterized in that: Heat to 350-700°C and maintain for 8-24 hours, then cool to room temperature.

4. The method for preparing a bimetallic electro-Fenton catalyst according to claim 1, characterized in that: The preparation method of the 1000-10000 mesh tourmaline powder is to grind it in a ball milling jar of a high-energy planetary ball mill for 30 minutes to 180 minutes, and the ball milling medium is 5 to 10 zirconia balls with a size of 3 to 10 mm.

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