High-efficiency water treatment agent, preparation method and application thereof

Abstract

The application provides a high-efficiency water treatment agent and a preparation method and application thereof, and relates to the technical field of water treatment.The preparation method of the water treatment agent comprises the following steps: (1) mixing nano-Fe3O4, potassium permanganate, manganese salt, potassium persulfate and water, wherein the mass ratio of the potassium permanganate, the potassium persulfate and the nano-Fe3O4 is 150-160:500-700:450-480; (2) performing a catalytic reaction under ultrasonic and ultraviolet conditions and at a temperature of 50-70 DEG C to obtain a composite magnetic Fe3O4-nano-MnO2; (3) separating the solid by using a magnet, washing, drying and obtaining the water treatment agent; and in the step (1), the nano-Fe3O4 is prepared by a coprecipitation method using an iron salt.The water treatment agent has a good treatment effect on high-COD-content wastewater, especially high-salt-and-COD-content wastewater and sewage, and has a high COD removal rate.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, specifically relating to a highly efficient water treatment agent, its preparation method, and its application. Background Technology

[0002] The increasing use of industrial water has led to the generation of large amounts of industrial wastewater. Industrial wastewater has a complex composition, especially water with high levels of COD (Chemical Oxygen Demand), suspended solids, dyes, and organic matter, resulting in poor biodegradability. COD (Chemical Oxygen Demand) is a measure of the amount of oxygen equivalent consumed by a chemical reaction in a water sample to oxidize reducing inorganic and organic matter (usually organic matter). It is a crucial indicator for assessing water pollution levels. In studies of river pollution and the properties of industrial wastewater, it is an important and relatively quick parameter for measuring organic pollution.

[0003] Effective removal of pollutants from water, reduction of water toxicity, and improvement of the biodegradability of wastewater or polluted water have attracted widespread attention. In recent years, ozone catalytic oxidation technology has been commonly used for the removal of organic pollutants from water, employing agents such as titanium dioxide, manganese dioxide, and copper oxide. Manganese dioxide is widely used due to its low toxicity, high stability, and environmental compatibility.

[0004] Chinese invention patent CN115106096A discloses a magnetic iron tetroxide / manganese dioxide core-shell structure material, its preparation method, and its application. The magnetic iron tetroxide / manganese dioxide core-shell structure material is a core-shell structure consisting of magnetic iron tetroxide spherical particles as the core and manganese dioxide flakes loaded on the surface as the shell. The preparation method is as follows: (1) Prepare iron tetroxide spherical particles; (2) Disperse the iron tetroxide spherical particles obtained in step (1) uniformly in deionized water, then slowly add concentrated hydrochloric acid to the mixture, stir for 5-20 min, add potassium permanganate, stir for 1-5 min, and sonicate for 5-30 min. After thorough dispersion, transfer to a high-pressure reactor, heat at 120-140℃ for 4-6 h, cool to room temperature, centrifuge, wash, and dry to obtain the magnetic iron tetroxide / manganese dioxide core-shell structure material. The magnetic iron tetroxide / manganese dioxide prepared by this invention has a core-shell structure, which can solve the problem of easy aggregation of manganese dioxide and achieve rapid catalyst recovery. This process requires high reaction temperature and pressure.

[0005] Chinese invention patent CN110586097A discloses a magnetic iron oxide / graphene oxide nanocomposite Fenton catalytic material and its preparation and application. This catalytic material has a Fe3O4 nano-hollow sphere structure and a wrinkled thin film structure of graphene oxide coating the surface of the hollow spheres. The specific preparation method is as follows: (1) dissolve graphene oxide in ultrapure water, sonicate, and collect the supernatant by centrifugation; (2) add ferric chloride hexahydrate, urea, and citric acid to the supernatant from (1), stir until homogeneous, add polyacrylic acid dropwise to the solution and mix until homogeneous, carry out a hydrothermal reaction, and finally separate the magnetic iron oxide / graphene oxide nanocomposite Fenton catalytic material by applying an external magnetic field, and wash with water and anhydrous ethanol respectively. The catalytic material of this invention exhibits different effects on COD at different pH levels. Cr The removal rates differ; for example, COD at pH=3... Cr The removal rate was 81.25% at pH=7 for COD. Cr The removal rate was 67.32%, demonstrating strong COD removal capabilities from wastewater. Cr The catalytic material of this invention requires the addition of graphene oxide, which increases its cost.

[0006] In their paper "Wang Donggang, Wang Zhimin. Study on the use of porous MnO2-Fe3O4 chitosan microspheres to enhance the Fenton-like degradation of dye wastewater [J]. Modern Chemical Industry, 2024, 44(S2):215-222. DOI:10.16606 / j.cnki.issn0253-4320.2024.S2.039," Wang Donggang and Wang Zhimin prepared metal chitosan microspheres (MnO2-Fe3O4 / Cs) by adding a mixed solution of chitosan and metal salt to an alkaline solution in a one-step process. These microspheres were then used for the Fenton-like degradation of Congo red (Cr). The results showed that compared with single-metal chitosan microspheres, MnO2-Fe3O4 / Cs exhibited better catalytic activity, with a Cr removal rate reaching up to 100%. However, these porous microspheres only have a high removal effect on low-content single Cr systems, and their effect is poor in the treatment of complex high-salt wastewater systems.

[0007] Although research on MnO2-Fe3O4 water treatment agents has gradually increased in recent years, most of these agents have complex compositions, loading other catalytic components onto the MnO2-Fe3O4 base. This not only increases costs but also makes the preparation process more cumbersome. Furthermore, existing technologies have limited research on COD levels in wastewater with high salt content and complex compositions; most agents only show good removal efficiency for a single pollutant.

[0008] Therefore, there is a need to provide a water treatment agent that has simple components, a simplified preparation method, and a high COD removal rate for complex wastewater with high salt content. Summary of the Invention

[0009] This invention addresses the problems existing in the prior art by providing a highly efficient water treatment agent, its preparation method, and its application. Under the action of ultrasound and ultraviolet light, nano-manganese dioxide is synthesized on the surface of magnetic iron oxide by hydrothermal co-precipitation, and is used to prepare a water treatment agent to achieve the technical effect of efficiently removing COD from wastewater with high salt content.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] First, this invention provides a method for preparing a highly efficient water treatment agent, comprising the following steps:

[0012] (1) Mix nano-iron oxide, potassium permanganate, manganese salt, potassium persulfate and water to obtain a mixture; the mass ratio of potassium permanganate, potassium persulfate and nano-iron oxide is 150-160:500-700:450-480.

[0013] (2) The mixture was heated to 50-70℃ under ultrasonic and ultraviolet conditions to carry out a catalytic reaction, and nano manganese dioxide was co-precipitated on the surface of nano iron oxide to obtain composite magnetic iron oxide-nano manganese dioxide.

[0014] (3) Use a magnet to separate the solid, rinse, and dry to obtain a highly efficient water treatment agent;

[0015] The nano-iron oxide mentioned in step (1) is prepared by co-precipitation of iron salts through a gradually increasing temperature.

[0016] Preferably, in step (1), the preparation method of the nano-iron oxide includes the following steps: ferric chloride and ferrous chloride are mixed with water, and the mixture is heated to 60-80°C in the presence of N2 for the first reaction; then ammonia is added for the second reaction; the mixture is heated to 80-95°C for the third reaction; and the nano-iron oxide is obtained by washing and magnetic screening.

[0017] More preferably, in step (1), the preparation method of the nano-Fe3O4 includes the following steps: dissolving 4-6 parts by weight of FeCl3·6H2O and 1-3 parts by weight of FeCl2·6H2O in 60-100 parts by weight of water; stirring and heating to 60-80℃ in the presence of N2 for a first reaction of 20-40 min; then adding 15-25 parts by weight of ammonia water with a volume concentration of 20%-30% for a second reaction of 20-40 min; then heating to 80-95℃ for a third reaction of 50-70 min; obtaining a black precipitate, washing with deionized water, and finally sieving with a magnet to obtain nano-Fe3O4.

[0018] More preferably, in step (1), the preparation method of the nano-Fe3O4 includes the following steps: 5.406 parts by weight of FeCl3·6H2O and 1.988 parts by weight of FeCl2·6H2O are dissolved in 80 parts by weight of water; the mixture is stirred and heated to 70°C in the presence of N2 for a first reaction of 30 min; then 20 g of ammonia water with a volume concentration of 25% is added for a second reaction of 30 min; the mixture is then heated to 90°C for a third reaction of 60 min; a black precipitate is obtained, which is washed with deionized water and finally screened with a magnet to obtain nano-Fe3O4.

[0019] Preferably, in step (1), the mass ratio of potassium permanganate, potassium persulfate, and nano-ferric oxide is 158:600:462.

[0020] Preferably, in step (1), the particle size of the nano-iron oxide is 10-50 nm.

[0021] More preferably, in step (1), the particle size of the nano-iron oxide is 10-35 nm.

[0022] In this invention, the nano-iron oxide used has a large specific surface area, which is beneficial for generating nano-manganese dioxide on the surface of nano-iron oxide.

[0023] Preferably, in step (1), the manganese salt is selected from one or more of manganese nitrate, manganese acetate, and manganese acetate.

[0024] More preferably, in step (1), the manganese salt is selected from manganese nitrate, manganese acetate, or a combination thereof.

[0025] Preferably, in step (1), the molar ratio of the manganese salt to potassium permanganate is 0.17-1.25:1.

[0026] More preferably, in step (1), the molar ratio of the manganese salt to potassium permanganate is 0.7-1.15:1.

[0027] More preferably, in step (1), the molar ratio of the manganese salt to potassium permanganate is 1:1.

[0028] Preferably, in step (1), the amount of water added is 6-15 times the mass of potassium permanganate.

[0029] More preferably, in step (1), the amount of water added is 10-13 times the mass of potassium permanganate.

[0030] Preferably, in step (2), the frequency of the ultrasound is 30-50Hz.

[0031] More preferably, in step (2), the frequency of the ultrasound is 40-45Hz.

[0032] Preferably, in step (2), the ultraviolet conditions have a power of 2.5-5 kW.

[0033] More preferably, in step (2), the ultraviolet conditions have a power of 3-3.5 kW.

[0034] Preferably, in step (2), the temperature of the catalytic reaction is 50-70℃ and the reaction time is 60-120min.

[0035] More preferably, in step (2), the temperature of the catalytic reaction is 63-70℃ and the reaction time is 90min.

[0036] More preferably, in step (2), the temperature of the catalytic reaction is 63°C and the reaction time is 90 min.

[0037] Preferably, in step (2), the ultrasound has the functions of stirring and heating; the ultraviolet treatment requires the use of an ultraviolet lamp, which plays a catalytic and heating role.

[0038] In step (2) of this invention, the catalytic reaction is to use nano-iron oxide as a crystal nucleus and react it with potassium permanganate, manganese salt and potassium persulfate under the action of ultrasound and ultraviolet light to co-precipitate nano-manganese dioxide on the surface of nano-iron oxide.

[0039] Preferably, in step (3), the solid separation is specifically achieved by magnetic separation of the obtained composite magnetic iron tetroxide-nano manganese dioxide using a magnet.

[0040] Preferably, in step (3), the rinsing specifically involves rinsing the obtained solid with pure water until the conductivity of the water is less than 10 μs / cm.

[0041] Preferably, in step (3), the drying process is specifically a drying treatment at ≤120℃.

[0042] Then, the present invention provides a water treatment agent prepared by the above preparation method, wherein the water treatment agent is composed of composite magnetic iron tetroxide-nano manganese dioxide.

[0043] Finally, this invention provides the application of the above-mentioned water treatment agents in the treatment of wastewater and sewage with high COD content.

[0044] Preferably, the COD content in the high-COD wastewater or sewage used in the application is ≥100mg / L.

[0045] Preferably, the application specifically refers to the application of water treatment agents in the treatment of high-salt, COD-containing wastewater and sewage.

[0046] More preferably, the high salt content specifically refers to a salt content ≥ 60 g / L.

[0047] Preferably, in the application, the water treatment agent removes COD from the water, with a COD removal rate of 80%-90%.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] 1. This invention synthesizes loaded nano-manganese dioxide on the surface of magnetic iron oxide under the action of ultrasound and ultraviolet light. The resulting composite magnetic iron oxide-nano-manganese dioxide is used as the main component of the reagent in the ozone catalytic oxidation process. It can efficiently remove COD from complex wastewater and polluted water with high salt content, so that the COD removal rate reaches 80%-90%.

[0050] 2. This invention utilizes ultrasound and ultraviolet reaction to prepare water treatment agents, avoiding energy-intensive operations such as hydrothermal and high-pressure processes, thus improving preparation efficiency; the resulting composite magnetic iron tetroxide-nano manganese dioxide structure is stable and can be efficiently reused.

[0051] 3. The composite magnetic iron tetroxide-nano manganese dioxide obtained by this invention can be separated and recovered by magnetic attraction during water treatment, thereby improving efficiency and reducing costs. Attached Figure Description

[0052] Figure 1 This is the XRD characterization diagram of the composite magnetic iron tetroxide-nano manganese dioxide prepared in Example 1 of this invention.

[0053] Figure 2 This is a TEM characterization image of the composite magnetic iron tetroxide-nano manganese dioxide prepared in Example 1 of this invention. Detailed Implementation

[0054] The following non-limiting embodiments are intended to enable those skilled in the art to gain a more comprehensive understanding of the present invention, but do not limit the invention in any way. The following content is merely an exemplary description of the scope of protection claimed by the present invention, and those skilled in the art can make various changes and modifications to the present invention based on the disclosed content, and such changes should also fall within the scope of protection claimed by the present invention.

[0055] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0056] The present invention will be further described below by way of specific embodiments. Unless otherwise specified, all chemical reagents used in the embodiments of the present invention are obtained through conventional commercial means.

[0057] Products from different manufacturers do not have a significant impact on the effect.

[0058] In some embodiments of the present invention, the nano-ferric oxide is nano-ferric oxide prepared by co-precipitation of iron salt through a gradually increasing temperature.

[0059] In some embodiments of the present invention, the preparation method of the nano-ferric oxide includes the following steps: ferric chloride and ferrous chloride are mixed with water, and the mixture is heated to 60-80°C in the presence of N2 to carry out a first reaction; then ammonia water is added to carry out a second reaction; the mixture is then heated to 80-95°C to carry out a third reaction; the mixture is washed and magnetically screened to obtain nano-ferric oxide; the nano-ferric oxide is magnetic.

[0060] In some embodiments of the present invention, the preparation method of the nano-ferric oxide includes the following steps: dissolving 4-6 parts by weight of FeCl3·6H2O and 1-3 parts by weight of FeCl2·6H2O in 60-100 parts by weight of water; stirring and heating to 60-80°C in the presence of N2 for a first reaction of 20-40 min; then adding 15-25 parts by weight of ammonia water with a volume concentration of 20%-30% for a second reaction of 20-40 min; then heating to 80-95°C for a third reaction of 50-70 min; obtaining a black precipitate, washing with deionized water, and finally screening with a magnet to obtain nano-ferric oxide; the nano-ferric oxide is magnetic.

[0061] In some embodiments of the present invention, the preparation method of the nano-ferric oxide includes the following steps: dissolving 5.406 parts by weight of FeCl3·6H2O and 1.988 parts by weight of FeCl2·6H2O in 80 parts by weight of water; stirring and heating to 70°C in the presence of N2 for a first reaction of 30 min; then adding 20 g of ammonia water with a volume concentration of 25% for a second reaction of 30 min; then heating to 90°C for a third reaction of 60 min; obtaining a black precipitate, washing with deionized water, and finally screening with a magnet to obtain nano-ferric oxide; the nano-ferric oxide is magnetic.

[0062] The nano-iron oxide obtained above is used as one of the raw materials for water treatment agents. The obtained water treatment agents can achieve a COD removal rate of more than 80% in high-salt wastewater as described in this invention.

[0063] Basic Example 1

[0064] The preparation method of nano-ferric oxide is as follows: 5.406g FeCl3·6H2O and 1.988g FeCl2·6H2O are dissolved in 80g of water; under the presence of N2, the mixture is stirred and heated to 70℃ for the first reaction for 30min; then 20g of ammonia water with a volume concentration of 25% is added for the second reaction for 30min; the temperature is then raised to 90℃ for the third reaction for 60min; a black precipitate is obtained, which is washed with deionized water and finally screened with a magnet to obtain nano-ferric oxide; the nano-ferric oxide is magnetic.

[0065] Basic Implementation Example 2

[0066] The preparation method of nano-ferric oxide is as follows: 4g FeCl3·6H2O and 1g FeCl2·6H2O are dissolved in 60g of water; under the presence of N2, the mixture is stirred and heated to 60℃ for the first reaction for 40min; then 15g of ammonia water with a volume concentration of 20% is added for the second reaction for 40min; the temperature is then raised to 80℃ for the third reaction for 70min; a black precipitate is obtained, which is washed with deionized water and finally screened with a magnet to obtain nano-ferric oxide; the nano-ferric oxide is magnetic.

[0067] Basic Example 3

[0068] The preparation method of nano-ferric oxide is as follows: 6g FeCl3·6H2O and 3g FeCl2·6H2O are dissolved in 100g of water; under the presence of N2, the mixture is stirred and heated to 80℃ for the first reaction for 20min; then 25g of ammonia water with a volume concentration of 30% is added for the second reaction for 20min; the temperature is then raised to 95℃ for the third reaction for 50min; a black precipitate is obtained, which is washed with deionized water and finally screened with a magnet to obtain nano-ferric oxide; the nano-ferric oxide is magnetic.

[0069] Example 1

[0070] The preparation method of high-efficiency water treatment agents is as follows:

[0071] (1) Mix 158g of potassium permanganate, 173g of manganese acetate, 600g of potassium persulfate with 1600mL of water, and then add 462g of nano-iron oxide (basic example 1);

[0072] (2) Turn on the ultrasonic generator and control the power at 45 Hz; turn on the ultraviolet lamp and control the power at 3.5 kW; stir the reaction at 63 ℃ for 90 min. After the reaction, nano manganese dioxide is generated on the surface of iron oxide to obtain composite magnetic iron oxide-nano manganese dioxide.

[0073] (3) Use a magnet to separate the solid, rinse the solid with deionized water, and dry it at 105°C to obtain a high-efficiency water treatment agent.

[0074] Example 2

[0075] The preparation method of high-efficiency water treatment agents is as follows:

[0076] (1) Mix 158g of potassium permanganate, 200g of manganese nitrate hexahydrate, and 600g of potassium persulfate with 2000mL of water, and then add 462g of nano-iron oxide (basic example 1);

[0077] (2) Turn on the ultrasonic generator and control the power at 45 Hz; turn on the ultraviolet lamp and control the power at 3.5 kW; stir the reaction at 70 ℃ for 90 min. After the reaction, nano manganese dioxide is generated on the surface of magnetic iron oxide to obtain composite magnetic iron oxide-nano manganese dioxide.

[0078] (3) Use a magnet to separate the solid, rinse the solid with deionized water, and dry it at 105°C to obtain a high-efficiency water treatment agent.

[0079] Example 3

[0080] The preparation method of high-efficiency water treatment agents is as follows:

[0081] (1) Mix 158g of potassium permanganate, 100g of manganese acetate, 100g of manganese nitrate hexahydrate, and 600g of potassium persulfate with 1800mL of water, and then add 462g of nano-iron oxide (basic example 1);

[0082] (2) Turn on the ultrasonic generator and control the power at 45 Hz; turn on the ultraviolet lamp and control the power at 3.5 kW; stir the reaction at 70 ℃ for 90 min. After the reaction, nano manganese dioxide is generated on the surface of magnetic iron oxide to obtain composite magnetic iron oxide-nano manganese dioxide.

[0083] (3) Use a magnet to separate the solid, rinse the solid with deionized water, and dry it at 105°C to obtain a high-efficiency water treatment agent.

[0084] Example 4

[0085] Unlike Example 1, the nano-ferric oxide used in step (1) is the nano-ferric oxide prepared in Example 2. Everything else is the same as in Example 1.

[0086] Example 5

[0087] Unlike Example 1, the nano-ferric oxide used in step (1) is the nano-ferric oxide prepared in Example 3. Everything else is the same as in Example 1.

[0088] Comparative Example 1

[0089] Magnetic iron oxide (Aladdin reagent, CAS: 1317-61-9) purchased from the market was used as raw material.

[0090] (1) Mix 158g of potassium permanganate, 173g of manganese acetate, 600g of potassium persulfate with 1600mL of water, and then add 462g of magnetic iron oxide purchased from the market.

[0091] (2) Turn on the ultrasonic generator and control the power at 45 Hz; turn on the ultraviolet lamp and control the power at 3.5 kW; stir the reaction at 63 ℃ for 90 min. After the reaction, nano manganese dioxide is generated on the surface of magnetic iron oxide to obtain magnetic iron oxide-nano manganese dioxide particles.

[0092] (3) Use a magnet to separate the solid, rinse the solid with deionized water, and dry it at 105°C to obtain the water treatment agent.

[0093] Comparative Example 2

[0094] Unlike Example 1, the amounts of potassium permanganate, potassium persulfate, and nano-ferric oxide are different.

[0095] (1) Mix 158g of potassium permanganate, 173g of manganese acetate, and 100g of potassium persulfate with 1600mL of water, and then add 462g of nano-magnetic iron oxide.

[0096] (2) Turn on the ultrasonic generator and control the power at 45 Hz; turn on the ultraviolet lamp and control the power at 3.5 kW; stir the reaction at 63 ℃ for 90 min. After the reaction, nano manganese dioxide is generated on the surface of magnetic iron oxide to obtain composite magnetic iron oxide-nano manganese dioxide.

[0097] (3) Use a magnet to separate the solid, rinse the solid with deionized water, and dry it at 105°C to obtain the water treatment agent.

[0098] Comparative Example 3

[0099] Unlike Example 1, the steps for loading nano-manganese dioxide are different, and this comparative example did not undergo ultraviolet treatment.

[0100] (1) Mix 158g of potassium permanganate, 173g of manganese acetate, 600g of potassium persulfate with 1600mL of water, and then add 462g of nano-magnetic iron oxide.

[0101] (2) Turn on the ultrasonic generator and control the power at 45 Hz; react for 90 min, and black particles are obtained after the reaction;

[0102] (3) Use a magnet to separate the solid, rinse the solid with deionized water, and dry it at 105°C to obtain the water treatment agent.

[0103] Comparative Example 4

[0104] Unlike Example 1, the steps for loading nano-manganese dioxide are different, and this comparative example did not undergo ultrasonic treatment.

[0105] (1) Mix 158g of potassium permanganate, 173g of manganese acetate, 600g of potassium persulfate with 1600mL of water, and then add 462g of nano-iron oxide;

[0106] (2) Turn on the ultraviolet lamp with a power of 3.5kw; stir the reaction at 63℃ for 90min to obtain a black flaky solid;

[0107] (3) Use a magnet to separate the solid, rinse the solid with deionized water, and dry it at 105°C to obtain the water treatment agent.

[0108] Comparative Example 5

[0109] Unlike Example 1, the reaction temperature for loading nano-manganese dioxide is different.

[0110] (1) Mix 158g of potassium permanganate, 173g of manganese acetate, 600g of potassium persulfate with 1600mL of water, and then add 462g of nano-magnetic iron oxide.

[0111] (2) Turn on the ultrasonic generator and control the power at 45 Hz; turn on the ultraviolet lamp and set the power to 3.5 kW; stir the reaction at 120 ℃ for 90 min and obtain black particles after the reaction.

[0112] (3) Use a magnet to separate the solid, rinse the solid with deionized water, and dry it at 105°C to obtain the water treatment agent.

[0113] The step (3) of rinsing the solid with deionized water described in the examples and comparative examples does not have many limitations on this step. It is only necessary to rinse until the conductivity of the water is less than 10 μs / cm.

[0114] Comparative Example 6

[0115] Unlike Example 1, the nano-iron oxide used in step (1) is different. In this comparative example, the nano-iron oxide was prepared by the following steps: 54.06g FeCl3·6H2O and 19.88g FeCl2·6H2O were dissolved in 80g of water; the mixture was stirred and heated to 70°C in the presence of N2 for a first reaction of 30min; then 20g of ammonia solution with a volume concentration of 25% was added for a second reaction of 90min; a black precipitate was obtained, which was washed with deionized water and finally screened with a magnet to obtain nano-iron oxide.

[0116] Comparative Example 7

[0117] The microsphere catalyst was prepared according to the method described in the article "Study on the use of porous MnO2-Fe3O4 chitosan microspheres to enhance the degradation of dye wastewater by Fenton".

[0118] 1.5 g of chitosan (CS) was dissolved in 50 mL of 2.5% acetic acid solution. Then, 5 mmol of Mn(NO3)2, 3.3 mmol of Fe(NO3)3·9H2O, and 1.67 mmol of FeSO4·7H2O (total metal salt = 10 mmol) were added and stirred thoroughly until completely dissolved to obtain a chitosan-metal salt mixed solution. The chitosan-metal salt mixed solution was then added dropwise to 1.25 mol / L NaOH using a peristaltic pump to obtain gel spheres. These spheres were aged in NaOH solution at 60 °C for 6 h, then washed with distilled water until the pH was neutral to obtain metal microspheres. Finally, the metal microspheres were freeze-dried to obtain bimetallic chitosan microspheres MnO2-Fe3O4 with a porous structure.

[0119] Experiment 1 COD Removal Experiment

[0120] Using coal chemical wastewater as the subject of investigation, the water quality indicators of the coal chemical wastewater before treatment are shown in Table 1. Besides a high COD concentration, this water quality is characterized by a high salt content; increased salt concentration will increase the difficulty of COD removal from the water.

[0121] Table 1

[0122]

[0123] Five g of the water treatment agents obtained in each example and comparative example were added to 500 mL of the same batch of coal chemical wastewater. The COD concentration of the coal chemical wastewater was 623 mg / mL. The pH was adjusted to 9-9.5 using sodium hydroxide. Ozone was introduced during the treatment process at a flow rate of 5 mL / min for 1.5 hours. After treatment, the water treatment agents were recovered by magnetic separation, and the COD concentration in the treated wastewater was measured.

[0124] Blank control group: No water treatment chemicals were used; only ozone was introduced for ozone treatment.

[0125] The COD concentration results of the treated coal chemical wastewater are shown in Table 2.

[0126] Table 2

[0127]

[0128] As shown in Table 2, the water treatment agent (composite magnetic iron oxide-nano manganese dioxide) of the present invention can efficiently remove COD from high-salinity coal chemical wastewater, significantly reducing the COD content. In Comparative Example 1, after replacing the nano magnetic iron oxide with commercially available magnetic iron oxide, the COD removal rate significantly decreased, and Fe ions were precipitated from the treated water, causing the effluent to turn red and further aggravating water pollution. In Comparative Example 2, after changing the ratio of potassium permanganate, manganese acetate, potassium persulfate, and nano iron oxide, the COD removal rate of the resulting water treatment agent was significantly reduced. In Comparative Examples 3 and 4, after changing the loading method (not using UV treatment and ultrasonic treatment respectively), the COD removal effect of the resulting water treatment agents was significantly reduced. The UV treatment and ultrasonic treatment of the present invention have a synergistic effect, resulting in a synergistic improvement in COD removal rate. In Comparative Example 5, after changing the reaction temperature of the loaded nano manganese dioxide, the wastewater still contained a large amount of COD, and the COD removal rate was reduced, failing to achieve the high COD removal rate technical effect described in the present invention.

[0129] Experiment 2 Characterization Test

[0130] XRD characterization method: When X-rays act on a crystal, they produce a specific diffraction pattern. The phase composition and structure of the material are analyzed based on the peak positions of the pattern. Test conditions: Cu Ka radiation; tube voltage: 40 kV; tube current: 200 mA; scan speed: 0.1 s / step; step size: 0.02° / step; scan range: 10° to 80°.

[0131] TEM characterization method: The test sample procedure is as follows: take a small amount of sample, add a small amount of anhydrous ethanol, and disperse evenly by ultrasonication. Take a drop of the dispersion and apply it to a copper grid. After drying, observe its powder morphology and particle size.

[0132] from Figure 1 As can be seen from the results, the composite magnetic iron tetroxide-nano manganese dioxide obtained in Example 1 exhibits an amorphous structure in XRD crystal form, and the XRD crystal form results show that this water treatment agent is beneficial to the catalytic reaction.

[0133] from Figure 2 As can be seen from the results, the composite magnetic iron tetroxide-nano manganese dioxide obtained in Example 1 exhibits a chestnut shell-like needle-shaped spherical cluster structure. This structure has a large surface area, which is beneficial for providing the area for catalytic reaction and improving catalytic reaction efficiency and COD removal rate.

[0134] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing a high efficiency water treatment agent, characterized by, The method comprises the steps of: (1) mixing nano-Fe3O4, potassium permanganate, manganese salt, potassium persulfate and water to obtain a mixture; the mass ratio of the potassium permanganate, the potassium persulfate and the nano-Fe3O4 is 150-160:500-700:450-480; (2) under ultrasonic and ultraviolet conditions, the mixture is heated to 50-70 DEG C to perform a catalytic reaction, and nano-MnO2 is co-precipitated on the surface of the nano-Fe3O4 to obtain a composite magnetic Fe3O4-nano-MnO2; (3) separating the solid by using a magnet, washing, drying to obtain a water treatment agent; In step (1), the preparation method of the nano-Fe3O4 comprises the steps of: mixing FeCl3 and FeCl2 with water, and heating to 60-80 DEG C under the condition of N2 to perform a first reaction; then adding ammonia water to perform a second reaction; and heating to 80-95 DEG C to perform a third reaction; washing, and magnetically screening to obtain the nano-Fe3O4.

2. The production method according to claim 1, characterized by, In step (1), the preparation method of the nano-Fe3O4 comprises the steps of: dissolving 4-6 parts by weight of FeCl3·6H2O and 1-3 parts by weight of FeCl2·6H2O in 60-100 parts by weight of water; stirring and heating to 60-80 DEG C under the condition of N2 to perform a first reaction for 20-40 min; then adding 15-25 parts by weight of ammonia water with a volume concentration of 20%-30% to perform a second reaction for 20-40 min; and heating to 80-95 DEG C to perform a third reaction for 50-70 min; obtaining a black precipitate, washing with deionized water, and finally magnetically screening to obtain the nano-Fe3O4.

3. The preparation method according to claim 1, characterized in that, In step (1), the mass ratio of the potassium permanganate, the potassium persulfate and the nano-Fe3O4 is 158:600:

462.

4. The method of claim 1, wherein, In step (1), the particle size of the nano-Fe3O4 is 10-50 nm; and the manganese salt is selected from one or more of manganese nitrate, manganese acetate and manganese acetate.

5. The preparation method according to claim 1, characterized in that, In step (1), the molar ratio of the manganese salt to the potassium permanganate is 0.17-1.25:

1.

6. The method of claim 1, wherein, In step (2), the frequency of the ultrasonic is 30-50 Hz; and the power of the ultraviolet condition is 2.5-5 kw. In step (2), the temperature of the catalytic reaction is 50-70 DEG C, and the reaction time is 60-120 min.

7. The preparation method according to claim 1, characterized in that, In step (3), the solid is separated by magnetically selecting and separating the obtained composite magnetic Fe3O4-nano-MnO2 by using a magnet; In step (3), the washing is specifically washing the obtained solid by using pure water until the conductivity of the water is less than 10 μs / cm.

8. The water treatment agent produced by the production process according to any one of claims 1 to 7, characterized in that, The water treatment agent is the composite magnetic Fe3O4-nano-MnO2.

9. The application of the water treatment agent of claim 8 in high-COD wastewater treatment.

10. The application of the water treatment agent of claim 8 in high-COD sewage treatment.

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