Preparation method of micro-electrolysis filler for wastewater containing thiocyanate and application thereof

Abstract

This invention discloses a method for preparing a micro-electrolysis packing material for thiocyanate-containing wastewater: Raw materials are sieved, mixed, and formed into spheres of 1-1.5 cm in size, then dried. The raw materials include 14-50 parts iron powder, 6-47 parts activated carbon powder, 4-35 parts copper powder, 20-40 parts sodium-based bentonite, and 1-5 parts pore-forming agent. The iron powder is sieved through a 60-mesh sieve, and the undersize is then sieved through an 80-mesh sieve, with the remaining material collected. The activated carbon powder is sieved through an 80-mesh sieve, and the undersize is then sieved through a 100-mesh sieve, with the remaining material collected. The copper powder is sieved through a 160-mesh sieve, and the undersize is then sieved through a 200-mesh sieve, with the remaining material collected. The binder is sieved through a 200-240-mesh sieve, and the undersize is collected. After calcination, the spheres are magnetized in a 10-40 Mt magnetic field for 10-40 min. This invention also discloses the application of the prepared packing material in the micro-electrolysis treatment of thiocyanate. The micro-electrolysis packing material prepared by this invention for thiocyanate-containing wastewater has a high removal rate and a long service life in the pH range of 3 to 9 of the wastewater.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology containing thiocyanate, and particularly relates to a method for preparing and applying a micro-electrolysis packing material for thiocyanate-containing wastewater. Background Technology

[0002] Thiocyanate is a major component of emissions from the coking industry. It is a toxic pollutant that harms human health and aquatic species. Thiocyanate is also widely found in wastewater from metallurgical, textile, dyeing, and rubber industries. Although thiocyanate is less toxic than cyanide, it is more difficult to degrade and hydrolyze, and incomplete oxidation can lead to the formation of cyanide. Furthermore, when thiocyanate concentrations exceed certain limits, it can cause significant harm to the environment and humans. The harmless treatment of thiocyanate-containing wastewater mainly includes biological, physical, and chemical methods. Biological methods, due to the relatively fragile activity of microorganisms, are only suitable for treating low concentrations of thiocyanate. Physical methods, such as adsorption and ion exchange, cannot achieve harmless treatment of thiocyanate and are ineffective. Chemical methods, including coagulation sedimentation, wet oxidation, and ozone oxidation, are more effective than physical methods but are costly to implement. Chemical methods have received widespread attention as efficient treatment approaches. Currently, alkaline chlorination is commonly used, where strong chlorination directly oxidizes thiocyanate into carbon dioxide and nitrogen. However, this method generates sludge and forms highly toxic cyanide. Furthermore, chemical wastewater treatment is often subject to strict pH limitations, with applicable wastewater pH ranges limited to acidic or alkaline conditions. This is particularly true for thiocyanate treatment, where improper handling can easily produce toxic cyanides, resulting in a lack of effective and low-cost chemical treatment technologies for thiocyanate in the current market.

[0003] The research and application of iron-carbon microelectrolysis technology provides a feasible approach to reduce the treatment cost of recalcitrant wastewater and achieve "waste-to-waste treatment." Microelectrolysis systems possess multiple functions, including oxidation, reduction, adsorption, and coagulation sedimentation, enabling the degradation and even complete mineralization of pollutants, making them a viable treatment technology for thiocyanate-containing wastewater. However, the microelectrolysis packing material, the material basis of iron-carbon microelectrolysis technology, currently suffers from low pH limitations, exhibiting high microelectrolysis capacity only under slightly acidic conditions, and is prone to passivation during operation. Therefore, there is an urgent need to develop a functional iron-carbon microelectrolysis packing material with wide pH adaptability and strong anti-caking ability for thiocyanate-containing wastewater. Summary of the Invention

[0004] The purpose of this invention is to provide a magnetized modified ternary micro-electrolysis packing material and its preparation method, which has a wide applicable pH range, high long-term stability, and high removal efficiency when used in the treatment of thiocyanate-containing wastewater.

[0005] The technical solution of this invention is as follows:

[0006] A method for preparing a micro-electrolysis packing material for thiocyanate-containing wastewater includes the following steps:

[0007] Step 1, making a sphere:

[0008] After sieving the raw materials, mix them evenly according to the following mass proportions, then add water and granulate them into spheres with a particle size of 1 to 1.5 cm, and dry them at 105 to 120°C.

[0009] The raw materials include: 14-50 parts iron powder, 6-47 parts activated carbon powder, 4-35 parts copper powder, 20-40 parts binder, and 1-5 parts pore-forming agent, wherein the binder is sodium-based bentonite; wherein, the iron powder is first passed through a 60-mesh sieve, the undersize is passed through an 80-mesh sieve, and the oversize is used as raw material; the activated carbon powder is first passed through an 80-mesh sieve, the undersize is passed through a 100-mesh sieve, and the oversize is used as raw material; the copper powder is first passed through a 160-mesh sieve, the undersize is passed through a 200-mesh sieve, and the oversize is used as raw material; the binder is passed through a 200-240-mesh sieve, and the undersize is used as raw material.

[0010] Step 2, calcination:

[0011] The spheres were calcined in a nitrogen atmosphere at a temperature of 650–800°C for 1.5–2.5 h; then cooled to room temperature in a nitrogen atmosphere to obtain a micro-electrolysis filler precursor.

[0012] Step 3, Magnetization Modification:

[0013] The obtained micro-electrolysis filler precursor was magnetized in a magnetic field with a magnetic field strength of 10–40 Mt for 10–40 min.

[0014] In the method of this invention, in the raw materials for making the spheres in step one, the particle size of iron powder, activated carbon powder, copper powder, and binder decreases sequentially. This allows the finer binder particles to fill the spaces between the iron powder, activated carbon powder, and copper powder after the spheres are formed, uniformly and firmly bonding them together. The resulting firmly bonded spheres have better bonding strength after calcination, and the iron and carbon components are spatially distributed regularly, making them less prone to pulverization and cracking during wastewater treatment. If excessively large binder particles are used, it is difficult to fill the gaps between the iron powder, activated carbon powder, and copper powder, resulting in poor bonding. The resulting spherical filler is prone to cracking and pulverization. The smaller gaps between the pulverized filler particles cause caking, further affecting the contact area between thiocyanate and iron and carbon, leading to a decrease in thiocyanate removal rate or premature filler failure. In the method of this invention, the particle size of copper powder in the prepared spheres is smaller than that of iron powder and activated carbon powder, while the particle size of iron powder is larger than that of activated carbon powder and copper powder. This different level of particle arrangement of different raw materials can achieve the following effects: the copper powder, as a catalytic particle, can connect the iron powder and carbon powder particles, acting as a bridge to maintain the connection between the two during the redox reaction of iron and carbon, thus better catalyzing the reaction, increasing the electron transfer rate, and generating more reactive oxygen species; the larger iron powder particles have a larger magnetic susceptibility, which is beneficial for magnetization modification and also for retaining more remanent magnetism after magnetization, and the remanent magnetism is not easily lost. The activated carbon powder has a moderate particle size range, and its own porous structure can be used to support the internal structure of the filler. The method of this invention, which adopts a technical solution of decreasing particle size of iron powder, activated carbon powder, copper powder, and binder, is beneficial for preparing micro-electrolysis fillers with strong magnetism, high reactivity, and resistance to caking. It can simultaneously meet the removal of thiocyanate from weakly acidic and weakly alkaline wastewater, and has a long service life. The pore-forming agent added to the raw materials generates gas during calcination, creating micropores in the spheres. This increases the contact area between thiocyanate ions and iron and carbon, thereby increasing the reaction area and improving the activity of the micro-electrolysis filler. Furthermore, the method of this invention magnetizes the micro-electrolysis filler precursor; the presence of residual magnetism affects copper, including Cu, in the system. + Cu 2+ The magnetic field force generated by the magnetic field enhances the catalytic ability of copper in the prepared micro-electrolysis packing, strengthens the catalytic effect of Cu in the ternary system, and broadens the applicable pH range of the packing.

[0015] Preferably, the pore-forming agent is ammonium bicarbonate. Ammonium bicarbonate has good water solubility and can be uniformly mixed with various raw materials through aqueous solution during sphere preparation. After drying, it is evenly distributed inside the sphere. Therefore, during calcination and gas generation, uniform and interconnected pores can be generated in the sphere, resulting in a porous filler with high reactivity.

[0016] Preferably, the magnetic field is generated by a neodymium iron boron (NdFeB) permanent magnet. NdFeB permanent magnets are convenient for generating magnetic fields and are suitable for the preparation of small batches of micro-electrolysis fillers. Of course, when preparing large batches of micro-electrolysis fillers, using a magnetic field generated by direct current for magnetization is more convenient and efficient.

[0017] Preferably, the iron powder is reduced iron powder. Reduced iron powder has a relatively loose microstructure and a large specific surface area, which makes it easier to mix evenly with activated carbon powder and copper powder. The resulting micro-electrolysis filler has high reactivity and strong thiocyanate removal ability.

[0018] This invention also provides a micro-electrolysis packing material for thiocyanate-containing wastewater, prepared by the above-described method. The micro-electrolysis packing material prepared by the method of this invention utilizes raw materials with decreasing particle sizes in the order of iron powder, activated carbon powder, copper powder, and binder, and undergoes magnetization treatment after calcination to prepare the micro-electrolysis packing material precursor. This results in a micro-electrolysis packing material that is not prone to cracking and pulverization, exhibits high reactivity, is suitable for a wide pH range of wastewater, has high thiocyanate removal efficiency, and has a long service life.

[0019] This invention also provides the application of the aforementioned micro-electrolysis packing material for thiocyanate-containing wastewater, comprising the following steps:

[0020] Step 1: Adjust the pH of the wastewater containing thiocyanate to 3-9;

[0021] Step two: Add the micro-electrolysis packing material for thiocyanate-containing wastewater to the wastewater and aerate the water with oxygen or air.

[0022] The micro-electrolysis packing material of the present invention for treating thiocyanate-containing wastewater exhibits high removal rates and long service life within a pH range of 3 to 9.

[0023] The beneficial effects of this invention are as follows:

[0024] The magnetized modified ternary micro-electrolysis packing material prepared by the method of this invention exhibits high removal rates and long service life in the treatment of thiocyanate-containing wastewater within a pH range of 3-9. In engineering applications, it significantly reduces the amount of acid added during the initial stage of micro-electrolysis, thereby lowering process costs. The magnetized modified ternary micro-electrolysis packing material prepared by the method of this invention can also achieve the above objectives in other industrial wastewater treatment fields. Detailed Implementation

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

[0026] Example 1

[0027] A micro-electrolysis packing material for thiocyanate-containing wastewater is prepared by the following method:

[0028] Step 1, making a sphere:

[0029] After sieving the raw materials, mix them evenly according to the following mass proportions, then add water and granulate them into spheres with a particle size of 1.2 cm; dry at 105℃.

[0030] The raw materials include: 30 parts reduced iron powder, 20 parts activated carbon powder, 30 parts copper powder, 25 parts sodium bentonite binder, and 3 parts ammonium bicarbonate pore-forming agent; wherein, the reduced iron powder is first passed through a 60-mesh sieve, the undersize is then passed through an 80-mesh sieve, and the remaining material is used as raw material; the activated carbon powder is first passed through an 80-mesh sieve, the undersize is then passed through a 100-mesh sieve, and the remaining material is used as raw material; the copper powder is first passed through a 160-mesh sieve, the undersize is then passed through a 200-mesh sieve, and the remaining material is used as raw material; the sodium bentonite binder is passed through a 200-mesh sieve, and the undersize is used as raw material.

[0031] Step 2, calcination:

[0032] The spheres were calcined in a nitrogen atmosphere at a temperature of 700°C for 2.0 h; then cooled to room temperature in a nitrogen atmosphere to obtain a micro-electrolysis filler precursor.

[0033] Step 3, Magnetization Modification:

[0034] The obtained micro-electrolysis packing precursor was magnetized in a magnetic field generated by a neodymium iron boron permanent magnet for 30 minutes with a magnetic field strength of 30MT, thus obtaining a micro-electrolysis packing for thiocyanate-containing wastewater.

[0035] Example 2

[0036] A micro-electrolysis packing material for thiocyanate-containing wastewater is prepared by the following method:

[0037] Step 1, making a sphere:

[0038] After sieving the raw materials, mix them evenly according to the following mass proportions, then add water and granulate them into spheres with a particle size of 1.5 cm; dry at 120℃.

[0039] The raw materials include: 50 parts iron powder, 47 parts activated carbon powder, 35 parts copper powder, 40 parts sodium bentonite binder, and 5 parts ammonium bicarbonate pore-forming agent; wherein, the iron powder is first passed through a 60-mesh sieve, the undersize is then passed through an 80-mesh sieve, and the remaining material is used as raw material; the activated carbon powder is first passed through an 80-mesh sieve, the undersize is then passed through a 100-mesh sieve, and the remaining material is used as raw material; the copper powder is first passed through a 160-mesh sieve, the undersize is then passed through a 200-mesh sieve, and the remaining material is used as raw material; the sodium bentonite binder is passed through a 240-mesh sieve, and the undersize is used as raw material.

[0040] Step 2, calcination:

[0041] The spheres were calcined in a nitrogen atmosphere at a temperature of 800°C for 2.5 hours; then cooled to room temperature in a nitrogen atmosphere to obtain a micro-electrolysis filler precursor.

[0042] Step 3, Magnetization Modification:

[0043] The obtained micro-electrolysis packing precursor was magnetized in a magnetic field generated by a neodymium iron boron permanent magnet for 40 minutes with a magnetic field strength of 40MT, thus obtaining a micro-electrolysis packing for thiocyanate-containing wastewater.

[0044] Example 3

[0045] A micro-electrolysis packing material for thiocyanate-containing wastewater is prepared by the following method:

[0046] Step 1, making a sphere:

[0047] After sieving the raw materials, mix them evenly according to the following mass proportions, then add water and granulate them into spheres with a particle size of 1.0 cm; dry at 115℃.

[0048] The raw materials include: 14 parts reduced iron powder, 6 parts activated carbon powder, 4 parts copper powder, 20 parts binder, and 1 part pore-forming agent ammonium bicarbonate. The binder is sodium-based bentonite. The reduced iron powder is first passed through a 60-mesh sieve, the undersize is then passed through an 80-mesh sieve, and the remaining material is used as raw material. The activated carbon powder is first passed through an 80-mesh sieve, the undersize is then passed through a 100-mesh sieve, and the remaining material is used as raw material. The copper powder is first passed through a 160-mesh sieve, the undersize is then passed through a 200-mesh sieve, and the remaining material is used as raw material. The sodium-based bentonite binder is passed through a 200-mesh sieve, and the undersize is used as raw material.

[0049] Step 2, calcination:

[0050] The spheres were calcined in a nitrogen atmosphere at a temperature of 650°C for 1.5 hours; then cooled to room temperature in a nitrogen atmosphere to obtain the micro-electrolysis filler precursor.

[0051] Step 3, Magnetization Modification:

[0052] The obtained micro-electrolysis packing precursor was magnetized for 10 minutes in a magnetic field with a magnetic field strength of 10MT generated by a neodymium iron boron permanent magnet to obtain a micro-electrolysis packing for thiocyanate-containing wastewater.

[0053] Example 4

[0054] A micro-electrolysis packing material for thiocyanate-containing wastewater is prepared by the following method:

[0055] Step 1, making a sphere:

[0056] After sieving the raw materials, mix them evenly according to the following mass proportions, then add water and granulate them into spheres with a particle size of 1.2 cm; dry at 105℃.

[0057] The raw materials include: 50 parts iron powder, 6 parts activated carbon powder, 35 parts copper powder, 30 parts binder, and 3 parts pore-forming agent ammonium bicarbonate. The binder is sodium-based bentonite. The iron powder is first passed through a 60-mesh sieve, the undersize is then passed through an 80-mesh sieve, and the remaining material is used as raw material. The activated carbon powder is first passed through an 80-mesh sieve, the undersize is then passed through a 100-mesh sieve, and the remaining material is used as raw material. The copper powder is first passed through a 160-mesh sieve, the undersize is then passed through a 200-mesh sieve, and the remaining material is used as raw material. The sodium-based bentonite binder is passed through a 200-mesh sieve, and the undersize is used as raw material.

[0058] Step 2, calcination:

[0059] The spheres were calcined in a nitrogen atmosphere at a temperature of 700°C for 2.0 h; then cooled to room temperature in a nitrogen atmosphere to obtain a micro-electrolysis filler precursor.

[0060] Step 3, Magnetization Modification:

[0061] The obtained micro-electrolysis packing precursor was magnetized in a magnetic field with a strength of 30MT generated by a neodymium iron boron permanent magnet for 30 minutes to obtain a micro-electrolysis packing for thiocyanate-containing wastewater.

[0062] Example 5

[0063] A micro-electrolysis packing material for thiocyanate-containing wastewater is prepared by the following method:

[0064] Step 1, making a sphere:

[0065] After sieving the raw materials, mix them evenly according to the following weight proportions, then add water and granulate into spheres with a particle size of 1.2 cm; dry at 105℃:

[0066] The raw materials include: 14 parts iron powder, 47 parts activated carbon powder, 20 parts copper powder, 30 parts binder, and 3 parts pore-forming agent ammonium bicarbonate. The binder is sodium-based bentonite. The iron powder is first passed through a 60-mesh sieve, the undersize is then passed through an 80-mesh sieve, and the remaining material is used as raw material. The activated carbon powder is first passed through an 80-mesh sieve, the undersize is then passed through a 100-mesh sieve, and the remaining material is used as raw material. The copper powder is first passed through a 160-mesh sieve, the undersize is then passed through a 200-mesh sieve, and the remaining material is used as raw material. The sodium-based bentonite binder is passed through a 200-mesh sieve, and the undersize is used as raw material.

[0067] Step 2, calcination:

[0068] The spheres were calcined in a nitrogen atmosphere at a temperature of 700°C for 2.0 h; then cooled to room temperature in a nitrogen atmosphere to obtain a micro-electrolysis filler precursor.

[0069] Step 3, Magnetization Modification:

[0070] The obtained micro-electrolysis packing precursor was magnetized in a magnetic field with a strength of 30MT generated by a neodymium iron boron permanent magnet for 30 minutes to obtain a micro-electrolysis packing for thiocyanate-containing wastewater.

[0071] Comparative Example 1

[0072] A micro-electrolysis packing material for thiocyanate-containing wastewater was prepared. The only difference between the method and Example 1 is that the raw material for making the spheres in step one does not contain copper powder.

[0073] Comparative Example 2

[0074] A micro-electrolysis packing material for thiocyanate-containing wastewater was prepared. The only difference between this method and Example 1 is that the magnetization modification in step three was not performed.

[0075] Comparative Example 3

[0076] A micro-electrolysis packing material for thiocyanate-containing wastewater was prepared. The method differed from that in Example 1 in that: the reduced iron powder was first passed through a 160-mesh sieve, the undersize was passed through a 200-mesh sieve, and the oversize was used as raw material; the copper powder was first passed through a 60-mesh sieve, the undersize was passed through an 80-mesh sieve, and the oversize was used as raw material.

[0077] Comparative Example 4

[0078] A micro-electrolysis packing material for thiocyanate-containing wastewater was prepared. The method differed from that in Example 1 in that the binder sodium-based bentonite was first passed through a 60-mesh sieve, the undersize material was passed through an 80-mesh sieve, and the oversize material was used as raw material.

[0079] Application Example 1

[0080] The micro-electrolysis packing materials prepared in Examples 1 to 5 and Comparative Examples 1 to 4 for treating simulated wastewater containing thiocyanate were used. The concentration of thiocyanate in the simulated wastewater was 100 mg / L, the initial pH was 3, and the volume of the simulated wastewater was 100 mL. 50 g of the prepared micro-electrolysis packing material for thiocyanate-containing wastewater was added to each simulated wastewater, the air aeration rate was 2 L / min, the reaction temperature was 20-25℃, and the reaction time was 2 h. After 2 h, the removal rate of thiocyanate and the content of cyanide in the simulated wastewater system were tested, and the test results are shown in Table 1.

[0081] The method for determining thiocyanate ions is the ferric nitrate spectrophotometric method, where the absorbance is measured at 460 nm, and the SCN is obtained through a standard curve. - The content of.

[0082] The test method for cyanide is the isonicotinic acid-barbituric acid spectrophotometry, which measures the absorbance at a wavelength of 600 nm and obtains the CN value through a standard curve. - The content of.

[0083] Application Example 2

[0084] The micro-electrolysis packing materials prepared in Examples 1 to 5 and Comparative Examples 1 to 4 for treating simulated wastewater containing thiocyanate were used. The concentration of thiocyanate in the simulated wastewater was 100 mg / L, the initial pH was 7, and the volume of the simulated wastewater was 100 mL. 50 g of the micro-electrolysis packing material for thiocyanate-containing wastewater was added to the simulated wastewater, the aeration rate was 2 L / min, the reaction temperature was 20-25 °C, and the reaction time was 2 h. After 2 h, the removal rate of thiocyanate and the content of cyanide in the simulated wastewater system were tested using the same method as in Application Example 1. The test results are shown in Table 1.

[0085] Application Example 3

[0086] The micro-electrolysis packing materials prepared in Examples 1 to 5 and Comparative Examples 1 to 4 for treating simulated wastewater containing thiocyanate were used. The concentration of thiocyanate in the simulated wastewater was 100 mg / L, the initial pH was 9, and the volume of the simulated wastewater was 100 mL. 50 g of the micro-electrolysis packing material for thiocyanate-containing wastewater was added to the simulated wastewater, the aeration rate was 2 L / min, the reaction temperature was 20-25 °C, and the reaction time was 2 h. After 2 h, the removal rate of thiocyanate and the content of cyanide in the simulated wastewater system were tested using the same method as in Application Example 1. The test results are shown in Table 1.

[0087] Application Example 4

[0088] The micro-electrolysis packing materials prepared in Examples 1 to 5 and Comparative Examples 1 to 4 for treating simulated wastewater containing thiocyanate were subjected to cyclic treatment as follows:

[0089] 1) Prepare simulated wastewater with a thiocyanate concentration of 100 mg / L and an initial pH of 7.

[0090] 2) Take 100 mL of simulated wastewater, add 50 g of micro-electrolysis packing material for thiocyanate-containing wastewater, aerate at a rate of 2 L / min, react at a temperature of 20-25℃, and react for 2 hours.

[0091] 3) After 2 hours, the micro-electrolysis packing material used for thiocyanate-containing wastewater was filtered out. Then, 100 mL of simulated wastewater was taken, and the filtered micro-electrolysis packing material was added back into it. The air aeration rate was 2 L / min, the reaction temperature was 20-25℃, and the reaction time was 2 hours. A total of 8 treatments were performed on the newly prepared simulated wastewater to remove thiocyanate using the above method. The thiocyanate and cyanide content in the wastewater after the 8th treatment was tested, and the removal rate was calculated. The test results are shown in Table 1.

[0092] Table 1

[0093]

[0094] The results above show that;

[0095] The micro-electrolysis packing materials for thiocyanate-containing wastewater prepared using the method of the present invention (Examples 1 to 5) showed a thiocyanate removal rate of over 96% after 2 hours of treatment, regardless of whether the wastewater was acidic (pH 3) or alkaline (pH 9) simulated wastewater. The initial thiocyanate concentration was 100 mg / L, the packing material dosage was 50 g / 100 mL, and the aeration rate was 2 L / min. This demonstrates that the micro-electrolysis packing materials for thiocyanate-containing wastewater prepared using the method of the present invention are suitable for both acidic and alkaline wastewater, are not demanding in terms of pH value, and exhibit high thiocyanate removal efficiency. Table 1 also shows that when treating neutral wastewater, the micro-electrolysis packing materials prepared using the method of the present invention maintained a thiocyanate removal rate of over 95% after 8 cycles of treatment. This indicates that the micro-electrolysis packing materials for thiocyanate-containing wastewater prepared using the method of the present invention have a long service life.

[0096] The only difference between the micro-electrolysis packing material for thiocyanate-containing wastewater prepared in Comparative Example 1 and Example 1 is the absence of copper powder in the raw materials. As shown in Table 1, the micro-electrolysis packing material for thiocyanate-containing wastewater prepared in Comparative Example 1 exhibits a significantly lower thiocyanate removal rate when treating simulated wastewater under the same conditions. Even when treating neutral wastewater, the highest removal rate reached was only 78.0%. This indicates that the lack of copper catalysis significantly reduces the packing material's reactivity. Furthermore, after eight cycles of treatment, the thiocyanate removal rate of the micro-electrolysis packing material for thiocyanate-containing wastewater prepared in Comparative Example 1 decreased to a further 70.05%, demonstrating that the addition of copper effectively extended the packing material's lifespan. This may be due to the combined effect of the magnetic field and copper inhibiting the deposition of iron oxides on the packing surface, and the strong magnetic field on the packing surface attracting Fe. 2+ Cu 2+ The adhesion of Fe causes more local Fe / Cu galvanic reactions, accelerating the Fe... 2+ / Fe 3+ Cu + / Cu 2+ The transformation of Cu and Fe is a complex process. The combined effect of Cu and Fe includes generating more oxygen vacancies on the material surface, adsorbing more oxygen and producing more reactive oxygen species, lowering the reaction energy barrier, and increasing the micro-electrolysis reaction rate. Furthermore, Cu is pH-insensitive, and the presence of a magnetic field can accelerate the corrosion of Fe, thus broadening the pH range the reaction can adapt to. This wider pH range reduces the amount of acid required in the process, lowering wastewater treatment costs.

[0097] The only difference between Comparative Example 2 and Example 1 in the micro-electrolysis packing material for thiocyanate-containing wastewater is the absence of the magnetization modification in step three. As shown in Table 1, the micro-electrolysis packing material for thiocyanate-containing wastewater prepared in Comparative Example 2 exhibits a significantly lower thiocyanate removal rate when treating wastewater under the same conditions; especially when treating simulated wastewater with a pH of 9, the removal rate only reached 60.78%, a substantial decrease. This demonstrates that magnetization significantly improves the removal rate of thiocyanate under alkaline conditions. Furthermore, after eight cycles of treatment, the thiocyanate removal rate of the micro-electrolysis packing material for thiocyanate-containing wastewater prepared in Comparative Example 2 decreased even more significantly, dropping to 50.80%. This indicates that magnetization modification effectively improves the service life of the micro-electrolysis packing material. This is because the presence of a magnetic field enhances the catalytic activity of Cu: the residual magnetism of the magnetized packing material affects the Cu in the system. + Cu 2+ The magnetic field enhances the catalytic effect of Cu in the ternary system; magnetization allows the iron in the packing to maintain a certain corrosion rate under weakly alkaline conditions, broadens the applicable pH range of the packing, increases the transfer rate of charged particles in the system, accelerates electrochemical corrosion, and speeds up the micro-electrolysis reaction rate.

[0098] The only difference between the micro-electrolysis packing material for thiocyanate-containing wastewater prepared in Comparative Example 3 and Example 1 is the particle size of the reduced iron powder and copper powder. In Example 1, the reduced iron powder has a particle size of 80–60 mesh, and the copper powder has a particle size of 160–200 mesh, with the particle sizes of iron powder, activated carbon powder, copper powder, and binder decreasing in that order. In Comparative Example 3, the reduced iron powder has a particle size of 160–200 mesh, the copper powder has a particle size of 80–60 mesh, and the iron powder has the smallest particle size. As can be seen from the results in Table 1, the micro-electrolysis packing material for thiocyanate-containing wastewater prepared in Comparative Example 3 exhibits a significantly lower thiocyanate removal rate when treating wastewater under the same conditions; especially when treating simulated wastewater with a pH of 9, the removal rate is only 72.32%, a substantial decrease. It is evident that a reasonable combination of particle sizes for iron powder, activated carbon powder, copper powder, and binder significantly improves the removal rate of thiocyanate in wastewater. Furthermore, in Comparative Example 3, the removal rate of thiocyanate decreased even more significantly after eight cycles of micro-electrolysis packing material for treating thiocyanate-containing wastewater, dropping to 45.63%. This demonstrates that an unreasonable combination of raw material particle sizes significantly reduces the service life of the micro-electrolysis packing material. This result was also obtained from the comparison between Comparative Example 4 and Example 1. As can be seen from Table 1, in Comparative Example 4, the particle size of the binder in the raw materials was increased. The thiocyanate removal rate of the prepared micro-electrolysis packing for thiocyanate-containing wastewater decreased significantly, regardless of whether the wastewater was acidic or alkaline. In particular, when the micro-electrolysis packing for thiocyanate-containing wastewater prepared in Comparative Example 4 was cycled 8 times, the thiocyanate removal rate decreased to 44.65%. This was mainly due to the insufficient bonding strength of the spheres, which caused the spheres to crack or pulverize after repeated use. The spherical structure of the packing was destroyed, resulting in the packing caking and a smaller effective contact area between the packing and the wastewater.

[0099] It should be noted that the above descriptions of these embodiments are for the purpose of helping to understand the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described above can be combined with each other as long as they do not conflict with each other. In addition, the above are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

Claims

1. A method for preparing a micro-electrolysis packing material for thiocyanate-containing wastewater, characterized in that, Includes the following steps: Step 1, making a sphere: After sieving the raw materials, mix them evenly according to the following mass proportions, then add water and granulate them into spheres with a particle size of 1 to 1.5 cm, and dry them at 105 to 120°C. The raw materials include: 14-50 parts iron powder, 6-47 parts activated carbon powder, 4-35 parts copper powder, 20-40 parts binder, and 1-5 parts pore-forming agent, wherein the binder is sodium-based bentonite; wherein, the iron powder is first passed through a 60-mesh sieve, the undersize is passed through an 80-mesh sieve, and the oversize is used as raw material; the activated carbon powder is first passed through an 80-mesh sieve, the undersize is passed through a 100-mesh sieve, and the oversize is used as raw material; the copper powder is first passed through a 160-mesh sieve, the undersize is passed through a 200-mesh sieve, and the oversize is used as raw material; the binder is passed through a 200-240-mesh sieve, and the undersize is used as raw material. Step 2, calcination: The spheres were calcined in a nitrogen atmosphere at a temperature of 650–800°C for 1.5–2.5 h; then cooled to room temperature in a nitrogen atmosphere to obtain a micro-electrolysis filler precursor. Step 3, Magnetization Modification: The obtained micro-electrolysis filler precursor was magnetized in a magnetic field with a magnetic field strength of 10–40 Mt for 10–40 min.

2. The method for preparing the micro-electrolysis packing material for thiocyanate-containing wastewater as described in claim 1, characterized in that, The pore-forming agent is ammonium bicarbonate.

3. The method for preparing the micro-electrolysis packing material for thiocyanate-containing wastewater as described in claim 1, characterized in that, The magnetic field is generated by a neodymium iron boron permanent magnet.

4. The method for preparing the micro-electrolysis packing material for thiocyanate-containing wastewater as described in claim 1, characterized in that, The iron powder is reduced iron powder.

5. A micro-electrolysis packing material for thiocyanate-containing wastewater, characterized in that, It is made by any one of the methods of claims 1 to 4.

6. The application of the micro-electrolysis packing material for thiocyanate-containing wastewater as described in claim 5, characterized in that, Includes the following steps: Step 1: Adjust the pH of the wastewater containing thiocyanate to 3-9; Step two: Add the micro-electrolysis packing material for thiocyanate-containing wastewater to the wastewater and aerate the water with oxygen or air.

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