Method for synchronously generating potassium ferrate, potassium permanganate and iron and manganese oxides

Abstract

The invention relates to the technical field of organic pollutant sewage treatment agents, in particular to a method for synchronously generating potassium ferrate, potassium permanganate and iron and manganese oxides. Comprising the following steps: (1) mixing hydrochloric acid and potassium permanganate for reaction to generate chlorine; (2) adding chlorine into a potassium hydroxide solution, stirring, then adding potassium hydroxide solid, and reacting to obtain a mixed solution; (3) filtering the mixed solution, retaining filtrate, adding ferric salt and manganese salt into the filtrate at the temperature lower than 5 DEG C, and stirring for reaction; (4) filtering after the reaction, cleaning filter residues, drying and calcining to obtain iron and manganese oxides; and (5) adding the filtrate collected in the step (4) into a saturated potassium hydroxide solution, and recombining to obtain potassium ferrate and potassium permanganate. According to the method provided by the invention, while potassium permanganate and potassium ferrate are produced, iron and manganese oxides are prepared from solid filter residues in potassium permanganate and potassium ferrate, and the iron and manganese oxides can activate hydrogen peroxide to degrade organic pollutants in sewage.

Description

Technical Field

[0001] The invention relates to the technical field of organic pollutant sewage treatment agents, and in particular to a method for synchronously generating potassium ferrate, potassium permanganate and iron-manganese oxides. Background Art

[0002] Organic pollution in sewage is a complex and urgent problem, and the residues of certain drugs such as carbamazepine and sulfamethoxazole have exacerbated this challenge. These pollutants mainly come from multiple aspects, including urban sewage and medical wastewater. With the rapid advancement of urbanization, urban sewage not only contains a large amount of conventional organic matter such as carbohydrates, proteins, and oils, but also often contains residues of anti-epileptic drugs such as carbamazepine and antibiotics such as sulfamethoxazole. When these substances are decomposed by microorganisms, they will consume a large amount of dissolved oxygen in the water, causing water quality to deteriorate. At the same time, sewage discharged from many industrial fields also contains a wide variety of organic matter, including artificial synthetics and difficult-to-degrade substances, which together with drug residues pose a serious threat to water bodies. In addition, hydrocarbon compounds in organic sewage, especially polycyclic aromatic hydrocarbons, are carcinogenic, and together with drug residues, they pose a huge risk to aquatic ecosystems.

[0003] The hazards of organic pollution and drug residues should not be underestimated. First, when organic matter decomposes in water, it consumes a large amount of dissolved oxygen, causing hypoxia in the water body and deterioration of water quality. In severe cases, it even causes black and smelly water bodies, affecting the survival and reproduction of aquatic organisms. Drug residues such as carbamazepine and sulfamethoxazole may have direct toxic effects on aquatic organisms, interfere with their endocrine systems, and affect reproduction and growth. Secondly, some organic matter will produce toxic and harmful substances such as ammonia nitrogen and hydrogen sulfide during the decomposition process. These substances, together with drug residues, not only directly endanger aquatic organisms, but may also accumulate through the food chain and ultimately affect human health. For example, long-term exposure to water bodies containing drugs such as carbamazepine may put humans at risk of damage to the nervous system. Furthermore, organic pollution reduces the safety of water quality, causing the content of harmful substances in the water body to exceed the standard. Long-term drinking of such water may cause various health problems.

[0004] Faced with the severe challenges of organic pollution and drug residues, advanced oxidation technology has been widely used. Iron (Fe(VI)) oxidation technology has attracted attention due to its strong oxidation ability and green and pollution-free characteristics. Although iron can be produced by wet oxidation, electrochemical oxidation of sacrificial anodes, and melting method to prepare potassium ferrate, the output of iron production is low, and the solid filter residue in the iron production process is usually disposed of as useless waste. And because of the strong oxidizing properties of iron, it self-decomposes rapidly in water, especially in acidic water bodies. In the process of iron degradation of pollutants, conventional reducing anions and cations (Fe 2+ 、S2O4 2-、S2O3 2- 、CO3 - However, although this activation process of high iron can accelerate the degradation of organic matter in the early stage of redox, this activation process usually consumes high-valent iron species (Fe 4+ , Fe 5+ and Fe 6+ ).

[0005] Through the above analysis, the problems and defects of the prior art are as follows:

[0006] (1) The substances produced in the conventional high-Fe(VI) preparation process are single. Although the generated Fe(VI) has a very strong oxidizing ability, the decay process of high-Fe is too fast.

[0007] (2) The solid residue from the high-speed rail production process is usually disposed of as useless waste.

[0008] Therefore, the present invention is proposed. Summary of the invention

[0009] The object of the present invention is to provide a method for synchronously generating potassium ferrate, potassium permanganate and iron-manganese oxides, wherein the solid filter residue in the method can be recycled and used, and three organic polluted sewage treatment agents of potassium ferrate, potassium permanganate and iron-manganese oxides can be generated simultaneously.

[0010] The present invention provides a method for synchronously generating potassium ferrate, potassium permanganate and iron-manganese oxide, comprising the following steps:

[0011] (1) mixing hydrochloric acid and potassium permanganate to generate chlorine gas;

[0012] (2) adding chlorine gas to a potassium hydroxide solution and stirring, then adding potassium hydroxide solid, stirring for reaction, and obtaining a mixed solution;

[0013] (3) filtering the mixed solution to remove the precipitate, retaining the filtrate, adding iron salt and manganese salt to the filtrate at a temperature below 5° C., and stirring to react;

[0014] (4) filtering after the reaction, collecting the filtrate and the filter residue, washing the filter residue, drying it, and calcining it to obtain iron-manganese oxide;

[0015] (5) adding the filtrate collected in step (4) into a saturated potassium hydroxide solution, and recrystallizing to precipitate crystals to obtain a mixture of potassium ferrate and potassium permanganate.

[0016] Furthermore, the iron salt in step (3) is one of ferric nitrate, ferric chloride and ferric sulfate.

[0017] Furthermore, the manganese salt in step (3) is one of manganese nitrate, manganese chloride and manganese sulfate.

[0018] Furthermore, the iron salt in step (3) is ferric nitrate nonahydrate, and the manganese salt is manganese nitrate tetrahydrate.

[0019] Furthermore, the molar ratio of the iron salt to the manganese salt in step (3) is (1-6):(1-6).

[0020] Furthermore, in step (2), a potassium peroxide solution having a concentration of 600 g / L is used.

[0021] Furthermore, in the step (4), the drying temperature of the filter residue is 100-110°C, and the drying time is 24 hours; the calcination process is as follows: under an inert atmosphere, firstly, the temperature is increased to 680-720°C at a rate of 5°C / min, and the constant temperature pyrolysis is maintained for 3.8-4.2 hours, and then naturally cooled to room temperature.

[0022] The present invention provides an iron-manganese oxide prepared by the above method.

[0023] The invention provides an application of an iron-manganese oxide in sewage treatment. The iron-manganese oxide is used as a hydrogen peroxide activator to degrade the contents of carbamazepine and sulfamethoxazole in sewage by activating hydrogen peroxide.

[0024] Furthermore, the method comprises the following steps: adding the iron-manganese oxide into sewage, mixing evenly, and then adding hydrogen peroxide to mix evenly.

[0025] In summary, the present invention has the following advantages:

[0026] (1) The technical solution of the present invention can prepare three organic pollutant wastewater treatment agents. While producing potassium permanganate and potassium ferrate, iron-manganese oxides are also prepared using the solid filter residues therein. Although the oxidizing ability of potassium permanganate is not as good as that of potassium ferrate, the attenuation process of potassium permanganate is slower and can degrade organic pollutants more permanently.

[0027] (2) The present invention introduces manganese atoms having similar atomic radius, electronegativity and charge density as those of iron atoms into the ferric oxide material to obtain an iron-manganese oxide loaded with atoms of similar radius. The further distortion of the crystal lattice and the deprivation of oxygen atoms caused by calcination can change the electron spin density in the local oxygen atoms, improve the electron mobility, introduce new active centers and accelerate the catalytic electron transfer reaction, thereby enhancing the performance of activated hydrogen peroxide in degrading organic pollutants in wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 This is the apparent morphology of the iron-manganese oxide prepared in Example 1 of the present invention;

[0030] Figure 2 The XRD patterns of the iron-manganese oxides prepared in Example 1 and Comparative Example 1 of the present invention;

[0031] Figure 3 1 is the EPR graph of the iron-manganese oxide prepared in Example 1 of the present invention and Comparative Example 1;

[0032] Figure 4 is an EDS image of the iron-manganese oxide prepared in Example 1 of the present invention;

[0033] Figure 5 This is a surface morphology diagram of the metal oxide prepared in Comparative Example 1 of the present invention;

[0034] Figure 6 is an EDS image of the metal oxide prepared in Comparative Example 1 of the present invention;

[0035] Figure 7 This is a graph showing the degradation efficiency of carbamazepine in sewage by the iron-manganese oxides prepared in Examples 1-5 of the present invention;

[0036] Figure 8 This is a graph showing the degradation efficiency of carbamazepine in sewage by the metal oxides prepared in Comparative Examples 1-5 of the present invention;

[0037] Fig. 9 This is a graph showing the degradation efficiency of sulfamethoxazole in sewage by the iron-manganese oxides prepared in Examples 1-5 of the present invention;

[0038] Fig.10 This is a graph showing the degradation efficiency of sulfamethoxazole in sewage using the metal oxides prepared in Comparative Examples 1-5 of the present invention. DETAILED DESCRIPTION

[0039] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0041] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined. In addition, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0042] Example 1

[0043] A method for simultaneously generating potassium ferrate, potassium permanganate and iron-manganese oxide, the specific process is as follows:

[0044] (1) Take 165 mL of 37% hydrochloric acid and 26.7 g of potassium permanganate to slowly generate chlorine gas;

[0045] (2) adding chlorine gas to 100 mL of a cooled 600 g / L KOH solution, while magnetically stirring for 2 h, adding 60 g of KOH solid, stirring and cooling thoroughly to obtain a mixed solution;

[0046] (3) Filter the mixed solution using GF / C glass filter paper to remove potassium chloride precipitate and retain a high concentration of strongly alkaline potassium hypochlorite solution. Slowly add 4.04 g of Fe(NO3)·9H2O and 12.90 g of Mn(NO3)2·4H2O (the molar ratio of iron nitrate to manganese nitrate is 1:6) to the potassium hypochlorite solution at a temperature below 5°C and rapidly stir to react.

[0047] (4) After the reaction, filter and collect the filtrate and filter residue. After filtering and washing the filter residue with deionized water, place it in a 105°C constant temperature forced air drying oven for 24 hours. After drying, crush it with a high-speed crusher, and then pass it through a 100-mesh sieve to obtain a powder; take an appropriate amount of the obtained powder into a quartz boat and place it in a tube furnace. After placing it, pass nitrogen for 30 minutes to remove most of the air in the tube, heat it to 700°C at a rate of 5°C / min, maintain constant temperature for pyrolysis for 4 hours, and then cool it naturally to room temperature to obtain iron manganese oxide. The apparent morphology of the iron manganese oxide is as follows: Figure 1 As shown; XRD Figure 2 As shown, EDS Figure 4 As shown, it shows that the iron and manganese elements are successfully doped; EPR Figure 3 As shown, it indicates that the material has produced lattice oxygen deficiencies, forming oxygen vacancies.

[0048] (5) adding the filtrate collected in step (4) into a saturated potassium hydroxide solution, recrystallizing to precipitate crystals, and obtaining a mixture of potassium ferrate and potassium permanganate. The resulting mixture of potassium ferrate and potassium permanganate can be used to degrade organic pollutants in sewage. Although the oxidizing ability of potassium permanganate is not as good as that of potassium ferrate, the decay process of potassium permanganate is slower, and it can degrade organic pollutants more sustainably.

[0049] Example 2

[0050] A method for simultaneously generating potassium ferrate, potassium permanganate and iron-manganese oxides. The technical solution in this embodiment is basically the same as that in Example 1, except that: in step (3), 4.04 g of Fe(NO3)·9H2O and 6.45 g of Mn(NO3)2·4H2O are slowly added to the potassium hypochlorite solution, and the molar ratio of ferric nitrate to manganese nitrate is 1:3.

[0051] Example 3

[0052] A method for simultaneously generating potassium ferrate, potassium permanganate and iron-manganese oxides. The technical solution in this embodiment is basically the same as that in Example 1, except that: in step (3), 20.20 g of Fe(NO3)·9H2O and 12.44 g of Mn(NO3)2·4H2O are slowly added to the potassium hypochlorite solution, and the molar ratio of ferric nitrate to manganese nitrate is 1:1.

[0053] Example 4

[0054] A method for simultaneously generating potassium ferrate, potassium permanganate and iron-manganese oxides. The technical scheme in this embodiment is basically the same as that in Example 1, except that: in step (3), 12.12 g of Fe(NO3)·9H2O and 2.15 g of Mn(NO3)2·4H2O are slowly added to the potassium hypochlorite solution, and the molar ratio of ferric nitrate to manganese nitrate is 3:1.

[0055] Example 5

[0056] A method for simultaneously generating potassium ferrate, potassium permanganate and iron-manganese oxides. The technical scheme in this embodiment is basically the same as that in Example 1, except that: in step (3), 24.24 g of Fe(NO3)·9H2O and 2.15 g of Mn(NO3)2·4H2O are slowly added to the potassium hypochlorite solution, and the molar ratio of ferric nitrate to manganese nitrate is 6:1.

[0057] The iron-manganese oxide provided by the present invention is used in sewage treatment. The iron-manganese oxide provided by the present invention is loaded with oxygen vacancy (Oxygen vacancy, a defect structure after oxygen atoms in a crystal are deprived) and can be used as a hydrogen peroxide activator to degrade the content of carbamazepine and sulfamethoxazole in sewage by activating hydrogen peroxide. When used, the iron-manganese oxide is first added to the sewage, mixed evenly, and then hydrogen peroxide is added to mix evenly.

[0058] The organic pollutants mentioned in the present invention refer to common refractory organic antibiotics in the art such as carbamazepine and sulfamethoxazole.

[0059] Comparative Example 1

[0060] A method for preparing a metal oxide. The preparation method in this comparative example is basically the same as that in Example 1, except that no calcination is performed in step (4). The surface morphology of the prepared metal oxide is as follows: Figure 5 As shown, EDS Figure 6 shown.

[0061] Comparative Example 2

[0062] A method for preparing a metal oxide. The preparation method in this comparative example is basically the same as that in Example 2, except that: no calcination is performed in step (4).

[0063] Comparative Example 3

[0064] A method for preparing a metal oxide. The preparation method in this comparative example is basically the same as that in Example 3, except that: no calcination is performed in step (4).

[0065] Comparative Example 4

[0066] A method for preparing a metal oxide. The preparation method in this comparative example is basically the same as that in Example 4, except that: calcination is not performed in step (4).

[0067] Comparative Example 5

[0068] A method for preparing a metal oxide. The preparation method in this comparative example is basically the same as that in Example 5, except that: calcination is not performed in step (4).

[0069] The iron manganese oxide prepared in Example 1-5 and the metal oxide prepared in Comparative Example 1-5 were tested for the removal of organic matter in sewage. The specific process is as follows: the water body is simulated sewage, and two simulated sewages are set. The two simulated sewages contain sulfamethoxazole and carbamazepine, respectively, and the content is 20 μmol / L, and the amount of iron manganese oxide or metal oxide is 0.1g / L. The degradation experiment was carried out in a 250mL conical flask. During the reaction, a stirrer was added to the bottom of the conical flask to facilitate magnetic stirring, and the time interval was set for sampling. 1mL was sampled, and 0.2mL 2mol / L sodium thiosulfate was added to the sample immediately after sampling to quench the reaction, and then the concentration was determined by HPLC-MS / MS instrument. Each condition was tested in parallel 2 to 3 times, the volume of the reaction solution was 100mL, and the mass concentration of hydrogen peroxide in the system was 50mmol / L; during the test, iron manganese oxide or metal oxide was first added to the simulated sewage, mixed evenly, and then hydrogen peroxide was added.

[0070] Different manganese doping amounts have a great influence on the activation ability of the catalyst. In order to explore the effect of different Fe and Mn doping ratios on the removal of carbamazepine by activated hydrogen peroxide, the degradation experiment was carried out with the initial concentration of carbamazepine set at 20 μmol / L under the condition of 50 mmol / L hydrogen peroxide. Figure 7 and Figure 8 As shown, with the increase of reaction time, the removal rate of carbamazepine is significantly improved. After 1 hour of reaction, the removal rates of Examples 1-5 are 80%, 76%, 42%, 38%, and 32%, respectively, and the removal rates of Comparative Examples 1-5 are 39%, 38%, 32%, 30%, and 22%, respectively. The calcination at 700°C and Fe / Mn=1:6 system in Example 1 achieves the best effect on the degradation of carbamazepine by activated hydrogen peroxide. After 1 hour of reaction, the removal rate can reach 80%; the blank group with only pure hydrogen peroxide added has a degradation rate of 24% for carbamazepine.

[0071] In order to explore the effect of different Fe and Mn doping ratios on the removal of sulfamethoxazole by activated hydrogen peroxide, the degradation experiment was carried out with the initial concentration of sulfamethoxazole set at 20 μmol / L under the condition of 50 mmol / L hydrogen peroxide. Fig. 9 and Fig.10As shown, with the increase of reaction time, the removal rate of sulfamethoxazole is significantly improved. After 1 hour of reaction, the removal rates of Examples 1-5 are 83%, 89%, 41%, 40%, and 35%, respectively; the removal efficiencies of Comparative Examples 1-5 are 49%, 57%, 32%, 30%, and 28%, respectively. The calcined 700℃Fe / Mn=1:3 system in Example 2 achieves the best effect on the degradation of sulfamethoxazole by activated hydrogen peroxide. After 1 hour of reaction, the removal rate can reach 89%; the blank group with only pure hydrogen peroxide added has a degradation rate of 30% for sulfamethoxazole.

[0072] The calcination temperature of iron manganese oxide and the molar ratio of iron nitrate and manganese nitrate have a great influence on the catalytic performance of hydrogen peroxide. With the increase of the molar ratio of manganese nitrate, the addition of manganese nitrate increases the degradation ability of hydrogen peroxide on organic pollutants. The addition of manganese nitrate increases the lattice distortion of the material. The calcination with nitrogen increases the oxygen vacancies of the material, thereby activating hydrogen peroxide to degrade organic pollutants. The effect of pyrolysis temperature on the adsorption amount shows a similar trend. Further increase of manganese doping (1:6) does not significantly catalyze the degradation of organic pollutants by hydrogen peroxide.

[0073] The main reaction principle of the oxygen vacancy-carrying iron-manganese oxide activated hydrogen peroxide provided by the present invention is that the oxygen vacancy-carrying iron-manganese oxide, on the basis of manganese dioxide catalyzing hydrogen peroxide, can allow surface water to form bridged hydroxyl groups (HO-OH) near the oxygen vacancies through the oxygen vacancies, which are converted into hydroxyl radicals (·OH) to react with organic pollutants.

[0074] The present invention introduces manganese atoms with similar atomic radius, electronegativity and charge density as those of iron atoms into the ferric oxide material to obtain a metal oxide loaded with atoms of similar radius, and further distortion of the crystal lattice and deprivation of oxygen atoms are caused by calcination, thereby changing the electron spin density in the local oxygen atoms, improving the electron mobility, introducing new active centers and accelerating the catalytic electron transfer reaction, thereby enhancing the catalytic performance of the activated material in activating hydrogen peroxide to degrade organic pollutants in sewage.

[0075] At the same time, the preparation method provided by the present invention can produce potassium permanganate while preparing iron-manganese oxide. Although the oxidation ability of potassium permanganate solution is not as good as that of potassium ferrate, the decay process of potassium permanganate is slower and it can degrade organic pollutants more permanently.

[0076] The iron-manganese oxide provided by the present invention has abundant raw materials, relatively low cost and is easier to be promoted and applied in practice.

[0077] The present invention adopts innovative doping of iron and manganese atoms in the step of preparing potassium ferrate. Compared with the prior art, the present solution can not only turn waste into treasure and convert useless iron oxides into catalysts with catalytic properties, but also form potassium permanganate while forming potassium ferrate; at the same time, the introduction of the innovative calcination process further increases the oxygen vacancies of the material. The heating process of the present invention is 5°C / min, and the temperature is kept at 700°C for 4h. The programmed heating is conducive to improving the formation of oxygen vacancies and the exposure of active sites, which is convenient for the subsequent activation application of hydrogen peroxide.

[0078] The iron-manganese oxide provided by the present invention has similar radius atoms including Fe and Mn, which will not generate secondary pollution compared with traditional metal catalytic materials (Co, Ni). At the same time, the introduction of metal Mn atoms can break the lattice arrangement of iron oxide, increase the electron spin density of O atoms, improve electron mobility, promote the reaction of active sites, and significantly improve the degradation efficiency of organic pollutants in sewage by hydrogen peroxide. The generation of vacancies can make the material have additional energy levels, which can serve as specific reaction points of certain molecules in the catalytic process, convert attached oxygen into hydroxyl radicals, and further activate and degrade organic pollutants; however, the prior art method has not mentioned the simultaneous realization of the preparation of catalysts and the study of the catalytic performance of hydrogen peroxide in the process of preparing potassium ferrate or in the process of preparing potassium ferrate and potassium permanganate.

[0079] The iron-manganese oxide provided by the invention is environmentally friendly and can efficiently activate hydrogen peroxide at room temperature and under natural conditions to degrade organic pollution in sewage.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for simultaneously generating potassium ferrate, potassium permanganate and iron-manganese oxides, characterized in that: The following steps are involved: (1) mixing hydrochloric acid and potassium permanganate to generate chlorine gas; (2) adding chlorine gas to a potassium hydroxide solution and stirring, then adding potassium hydroxide solid, stirring for reaction, and obtaining a mixed solution; (3) filtering the mixed solution to remove the precipitate, retaining the filtrate, adding iron salt and manganese salt to the filtrate at a temperature below 5° C., and stirring to react; (4) filtering after the reaction, collecting the filtrate and the filter residue, washing the filter residue, drying it, and calcining it to obtain iron-manganese oxide; (5) adding the filtrate collected in step (4) into a saturated potassium hydroxide solution, and recrystallizing to precipitate crystals to obtain a mixture of potassium ferrate and potassium permanganate.

2. The method according to claim 1, characterized in that The iron salt in step (3) is one of ferric nitrate, ferric chloride and ferric sulfate.

3. The method according to claim 2, characterized in that The manganese salt in step (3) is one of manganese nitrate, manganese chloride and manganese sulfate.

4. The method according to claim 1, characterized in that The iron salt in step (3) is ferric nitrate nonahydrate, and the manganese salt is manganese nitrate tetrahydrate.

5. The method according to claim 1, characterized in that The molar ratio of the iron salt to the manganese salt in step (3) is (1-6):(1-6).

6. The method according to claim 1, characterized in that In the step (2), a potassium hydroxide solution with a concentration of 600 g / L is used.

7. The method according to claim 1, characterized in that In the step (4), the drying temperature of the filter residue is 100-110°C, and the drying time is 24 hours; the calcination process is as follows: under an inert atmosphere, firstly, the temperature is raised to 680-720°C at a rate of 5°C / min, and the constant temperature is maintained for 3.8-4.2 hours, and then naturally cooled to room temperature.

8. An iron-manganese oxide, characterized in that The method is prepared by any one of claims 1 to 7.

9. Use of the iron-manganese oxide according to claim 8 in sewage treatment, characterized in that: The iron-manganese oxide is used as a hydrogen peroxide activator to degrade the contents of carbamazepine and sulfamethoxazole in sewage by activating hydrogen peroxide.

10. The use according to claim 9, characterized in that: The following steps are involved: The iron-manganese oxide is added to the sewage, mixed evenly, and then hydrogen peroxide is added and mixed evenly.

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