Iron-based heterogeneous Fenton catalyst as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of organic wastewater treatment, and relates to an iron-based heterogeneous Fenton catalyst as well as a preparation method and application thereof. The invention aims to solve the technical problems that in the prior art, a heterogeneous Fenton catalyst needs an acidic condition to degrade organic pollutants, and under the acidic condition, the conversion rate of Fe (II) / Fe (III) is low, and the reaction needs a long time, so that the degradation efficiency is low. The invention provides an iron-based heterogeneous Fenton catalyst which comprises iron phosphide and Schwertmannite, the loading proportion of the iron phosphide on the catalyst is 10%-18%, and the catalyst promotes Fe (II) regeneration and is good in stability and high in catalytic performance. The invention also provides a preparation method of the catalyst, which comprises the following steps: adding iron phosphide into pure water, adding ferrous sulfate and / or a hydrate of ferrous sulfate into the obtained iron phosphide suspension, reacting, collecting precipitate, washing, and freeze-drying to obtain the catalyst. The invention further provides application of the iron-based heterogeneous Fenton catalyst, when the iron-based heterogeneous Fenton catalyst is used for degrading organic pollutants, acidic conditions are not needed, the catalytic performance is improved, and the degradation efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of organic wastewater treatment, and specifically relates to an iron-based heterogeneous Fenton catalyst and a preparation method and application thereof. Background Art

[0002] The heterogeneous Fenton reaction is an advanced oxidation technology using heterogeneous catalysts and hydrogen peroxide (H2O2), which is mainly used to degrade refractory pollutants in the aqueous phase. Transition metal-based materials are the most widely studied solid catalysts in the heterogeneous Fenton reaction. Among various transition metals, iron has the most abundant geological reserves and is harmless to the environment. However, traditional iron-based heterogeneous Fenton materials have the following disadvantages: (1) low Fe(II) / Fe(III) conversion rate; (2) acidic reaction conditions are required, usually with a pH value of 2.8 to 3.5, which limits the scope of application; (3) poor stability under acidic conditions. Therefore, good Fe(II) / Fe(III) conversion ability and acid resistance are crucial for the application of iron-based catalysts in the Fenton reaction.

[0003] Iron phosphide (FeP) has a high electron transfer ability, is conducive to iron circulation, and also has good acid resistance and stability. However, like traditional iron-based materials, FeP still requires acidic conditions during the heterogeneous Fenton reaction, and is easy to agglomerate, and cannot fully expose active sites. As a trivalent iron mineral, Schroeder mineral is easy to obtain in nature at a low cost. Since 2013, it has been used as a heterogeneous Fenton catalyst for phenol degradation. Although Schroeder mineral can be used as a heterogeneous Fenton catalyst, there is a long lag period in the Fenton reaction, which leads to a long time for pollutant degradation. This is mainly because the main iron species contained in Schroeder mineral is Fe(III), and the Fenton reaction is mainly the catalytic decomposition of H2O2 to produce ·OH by Fe(II), so the conversion of Fe(III) to Fe(II) is the prerequisite for initiating the Fenton reaction.

[0004] For example, the Chinese invention patent publication number CN108906094A, the application date is July 19, 2018, and the invention name is "A Fenton-like catalyst and its application in the rapid degradation of organic pollutants", which specifically discloses a Fenton-like catalytic system composed of FeP and H2O2 and its application in the rapid degradation of organic pollutants. As a catalyst for Fenton-like reactions, FeP can efficiently decompose H2O2 to produce hydroxyl radicals, and achieve the degradation of organic pollutants in a very short time (in seconds), but the reaction still needs to be carried out at a relatively low pH value (pH ≤ 3), which limits its application in the treatment of wastewater with different pH values. After the FeP catalyst reacts with the organic pollutants in the wastewater, it is difficult to separate and recover it from the treated water, which increases the difficulty and cost of subsequent treatment. For example, the Chinese invention patent publication number is CN113248003A, the application date is May 25, 2021, and the name of the invention is "A method for degrading chlordane in a cyclodextrin solution by a heterogeneous photo-Fenton reaction catalyzed by a Schmidt mineral", which discloses a method for catalytically degrading chlordane in a cyclodextrin solution under ultraviolet light irradiation using a Schmidt mineral as a catalyst, comprising the following steps: (1) adjusting the concentration of cyclodextrin in a cyclodextrin solution containing chlordane to 0.4 g / L to 1.5 g / L, adding a Schmidt mineral, and adjusting the pH value of the cyclodextrin solution to neutral or acidic; (2) adding hydrogen peroxide to the cyclodextrin solution of step (1), wherein the concentration of hydrogen peroxide is greater than 20 mmol / L; (3) in a photocatalytic reactor, irradiating the cyclodextrin solution with ultraviolet light under stirring conditions, and carrying out a degradation reaction at room temperature. This solution has the following shortcomings: the catalytic efficiency of Schmidtite under visible light irradiation is poor, and it can only show good catalytic activity under ultraviolet light irradiation. At the same time, when the pH is 3, the degradation rate of chlordane is 80%, and when the pH increases, the degradation rate decreases. This method has many restrictions.

[0005] In summary, it is an urgent problem to achieve efficient degradation of organic pollutants using a heterogeneous Fenton system without adjusting the pH value. Summary of the invention

[0006] 1. Problems to be solved

[0007] In view of the prior art, heterogeneous Fenton catalysts for degrading organic pollutants first need to adjust the pH value of the wastewater to acidic, but under acidic conditions, the Fe(II) / Fe(III) conversion rate is low, and the reaction takes a long time, resulting in a technical problem of low degradation efficiency. The present application provides an iron-based heterogeneous Fenton catalyst, which can solve the problems of low Fe(II) / Fe(III) conversion rate and low degradation efficiency without adjusting the initial pH value of the wastewater to acidic. The present application also provides a method for preparing the iron-based heterogeneous Fenton catalyst. At the same time, the present application also provides an application of the iron-based heterogeneous Fenton catalyst.

[0008] 2. Technical solution

[0009] In order to achieve the above purpose, the technical solution provided is:

[0010] An iron-based heterogeneous Fenton catalyst comprises iron phosphide and Schroederite; calculated by mass ratio, the loading ratio of the iron phosphide on the catalyst is 10% to 18%.

[0011] Furthermore, calculated by mass ratio, the loading ratio of the iron phosphide on the catalyst is 12% to 18%.

[0012] Furthermore, the catalyst also contains hydrogen peroxide; calculated by mass ratio, the hydrogen peroxide accounts for 4% to 33% of the catalyst.

[0013] Preferably, the concentration of the solid formed by the iron phosphide and the Schroeder mineral in the organic wastewater is 0.6 g / L to 1.2 g / L, and the concentration of the hydrogen peroxide in the organic wastewater is 50 mg / L to 300 mg / L.

[0014] A method for preparing an iron-based heterogeneous Fenton catalyst, characterized in that it comprises the following steps:

[0015] S1. Adding iron phosphide to pure water to obtain an iron phosphide suspension;

[0016] S2. Adding ferrous sulfate and / or ferrous sulfate hydrate to the iron phosphide suspension, and after the reaction, obtaining a precipitate;

[0017] S3. collecting the precipitate, washing, and freeze-drying to obtain the iron-based heterogeneous Fenton catalyst;

[0018] Calculated by mass ratio, the loading ratio of the iron phosphide on the catalyst is 10% to 18%.

[0019] Furthermore, the hydrate of ferrous sulfate is ferrous sulfate heptahydrate.

[0020] Furthermore, the mass ratio of the ferrous sulfate heptahydrate to the iron phosphide is 11-28:1.

[0021] Furthermore, in step S1, the suspension is prepared by ultrasonic dispersion; in step S2, the reaction is carried out in a constant temperature shaker.

[0022] An application of an iron-based heterogeneous Fenton catalyst, wherein the iron-based heterogeneous Fenton catalyst is applied to the treatment of organic wastewater; or the iron-based heterogeneous Fenton catalyst prepared by the method is applied to the treatment of organic wastewater.

[0023] Furthermore, before using the iron-based heterogeneous Fenton catalyst to treat the organic wastewater, there is no need to adjust the pH value of the organic wastewater.

[0024] Furthermore, the catalyst comprises iron phosphide and Schroeder mineral, and the amount thereof added to the organic wastewater is 0.6 g / L to 1.2 g / L; or the catalyst further comprises hydrogen peroxide, and the amount thereof added to the organic wastewater is 0.605 g / L to 1.5 g / L.

[0025] Preferably, the organic wastewater contains one or more of Acid Orange 7 at a concentration of 10 mg / L to 50 mg / L, Methylene Blue at a concentration of 10 mg / L to 50 mg / L, Ciprofloxacin at a concentration of 10 mg / L to 50 mg / L, and Rhodamine B at a concentration of 10 mg / L to 50 mg / L.

[0026] 3. Beneficial effects

[0027] Compared with the existing known technology, the technical solution provided by the present invention has the following beneficial effects:

[0028] (1) An iron-based heterogeneous Fenton catalyst of the present invention comprises a catalyst of iron phosphide and Schmidt mineral, wherein the loading mass ratio of the iron phosphide on the catalyst is 10% to 18%. Fe, S, P, and O elements are evenly distributed on the iron-based heterogeneous Fenton catalyst, and the P element promotes the conversion of Fe(II) / Fe(III) and accelerates the iron cycle; the initial organic wastewater does not need to adjust the pH value, and the Schmidt mineral of the catalyst contains SO 2 4 - The structure can be OH in water - Substitution, while releasing H + Even if the initial pH value is neutral, the pH after the reaction can be stabilized in the most suitable pH range for Fenton reaction (3.0-3.6). The catalyst has good stability, high catalytic performance, and is easy to recycle. The degradation rate of various organic pollutants such as acid orange 7, methylene blue, ciprofloxacin and rhodamine B can reach more than 90%.

[0029] (2) A method for preparing an iron-based heterogeneous Fenton catalyst of the present invention comprises adding iron phosphide to pure water to obtain an iron phosphide suspension; adding ferrous sulfate and / or ferrous sulfate hydrate to the iron phosphide suspension, and obtaining a precipitate after reaction; collecting the precipitate, washing, and freeze-drying to obtain an iron-based heterogeneous Fenton catalyst. The present application is to introduce iron phosphide into the process of chemical synthesis of Schrödinger mineral to prepare an iron phosphide-loaded Schrödinger mineral (Sch / FeP) heterogeneous Fenton catalyst, i.e., an iron-based heterogeneous Fenton catalyst. The preparation method only requires 3 steps to complete the preparation of the iron-based heterogeneous Fenton catalyst, is simple to operate, and the raw materials are easily available and low in cost.

[0030] (3) Application of an iron-based heterogeneous Fenton catalyst of the present invention, adding an iron-based heterogeneous Fenton catalyst to organic wastewater to carry out degradation reaction. The Fe in FeP carries a partial positive charge (Fe δ+ ,0<δ+<2), P in FeP has a partial negative charge (P δ- ,-1<δ-<0). Therefore, the Fe δ+ and P δ- It can provide electrons for Fe(III) reduction, accelerate iron cycle and Fe(II) regeneration performance. δ- It can also serve as an additional active site to activate H2O2 to produce reactive free radicals (such as ·OH), thereby improving the utilization rate of H2O2 and further improving the catalytic performance of the iron-based heterogeneous Fenton catalyst, which can rapidly degrade a variety of organic pollutants in water, with a degradation rate of more than 90%. The catalyst can drive excellent Fenton catalytic performance without adjusting the initial pH, and has good application prospects in the field of water treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The distribution diagram of Fe, S, P, and O elements in the Fe-based heterogeneous Fenton catalyst;

[0032] Figure 2 Catalytic degradation of AO7 (a), MB (b), CIP (c) and RhB (d) by iron phosphide, schreiterite and Fe-based heterogeneous Fenton catalysts;

[0033] Figure 3 is the utilization rate of H2O2 (a) and Fe in the reaction system of iron phosphide, Schottkynerite and Fe-based heterogeneous Fenton catalyst 2+ Dissolution amount (b). DETAILED DESCRIPTION

[0034] In order to further understand the content of the present invention, the present invention is described in detail in conjunction with embodiments.

[0035] Example 1

[0036] A method for preparing an iron-based heterogeneous Fenton catalyst (Sch / FeP) of the present embodiment comprises the following steps:

[0037] 0.3 g of FeP was added into 250 mL of pure water and dispersed by ultrasound for 10 min to obtain a FeP suspension;

[0038] Add 5.56 g of FeSO4·7H2O to the FeP concentration suspension (250 mL), the mass ratio of FeSO4·7H2O to FeP is 18.5:1, place in a multifunctional constant temperature shaker, react for 24 hours, and obtain a precipitate;

[0039] The precipitate is collected by a microporous filter membrane and washed with water to remove soluble impurities. The collected precipitate is freeze-dried to obtain an iron-based heterogeneous Fenton catalyst.

[0040] From TEM-Mapping, we can see (such as Figure 1 ), Fe, S, P, and O elements are evenly distributed on the iron-based heterogeneous Fenton catalyst, indicating that the Schmidtite and iron phosphide are successfully composited. The P element is determined by acid dissolving the catalyst and it is known that the loading ratio of FeP on the catalyst is 12%.

[0041] Example 2

[0042] A method for preparing an iron-based heterogeneous Fenton catalyst (Sch / FeP) of the present embodiment comprises the following steps:

[0043] 0.5 g of FeP was added into 250 mL of pure water and dispersed by ultrasound for 10 min to obtain a FeP suspension;

[0044] Add 5.56 g of FeSO4·7H2O to the FeP concentration suspension (250 mL), the mass ratio of FeSO4·7H2O to FeP is 11.12:1, place in a multifunctional constant temperature shaker, react for 24 h, and obtain a precipitate;

[0045] The precipitate is collected by a microporous filter membrane and washed with water to remove soluble impurities. The collected precipitate is freeze-dried to obtain an iron-based heterogeneous Fenton catalyst.

[0046] The P element was measured by acid dissolving the catalyst, and it was found that the loading ratio of FeP on the catalyst was 18%.

[0047] Example 3

[0048] A method for preparing an iron-based heterogeneous Fenton catalyst (Sch / FeP) of the present embodiment comprises the following steps:

[0049] 0.2 g of FeP was added into 250 mL of pure water and dispersed by ultrasound for 10 min to obtain a FeP suspension;

[0050] Add 5.56 g of FeSO4·7H2O to the FeP concentration suspension (250 mL), the mass ratio of FeSO4·7H2O to FeP is 27.8:1, place in a multifunctional constant temperature shaker, react for 24 hours, and obtain a precipitate;

[0051] The precipitate is collected by a microporous filter membrane and washed with water to remove soluble impurities. The collected precipitate is freeze-dried to obtain an iron-based heterogeneous Fenton catalyst.

[0052] The P element was measured by acid dissolving the catalyst, and it was found that the loading ratio of FeP on the catalyst was 10%.

[0053] Comparative Example 1

[0054] The preparation method of an iron-based heterogeneous Fenton catalyst (Sch / FeP) of this comparative example comprises the following steps:

[0055] 0.1 g of FeP was added into 250 mL of pure water and dispersed by ultrasound for 10 min to obtain a FeP suspension;

[0056] Add 5.56 g of FeSO4·7H2O to the FeP concentration suspension (250 mL), the mass ratio of FeSO4·7H2O to FeP is 55.6:1, place in a multifunctional constant temperature shaker, react for 24 hours, and obtain a precipitate;

[0057] The precipitate is collected by a microporous filter membrane and washed with water to remove soluble impurities. The collected precipitate is freeze-dried to obtain an iron-based heterogeneous Fenton catalyst.

[0058] The P element was measured by acid dissolving the catalyst, and it was found that the loading ratio of FeP on the catalyst was 6%.

[0059] It can be seen from Examples 1-3 and Comparative Example 1 that Fe, S, P, and O elements are evenly distributed on the iron-based heterogeneous Fenton catalyst, and the Schmidt mineral and iron phosphide are successfully compounded. Calculated by mass ratio, the loading ratio of FeP on the catalyst is 10% to 18%. If the loading ratio of FeP on the catalyst is too low, the Fe(II) / Fe(III) conversion rate is low, and the degradation rate of organic polluted wastewater is reduced. If the loading ratio of FeP on the catalyst is too high, it will cause a waste of FeP.

[0060] Example 4

[0061] The application of an iron-based heterogeneous Fenton catalyst (Sch / FeP) of this embodiment comprises the following steps:

[0062] In 50 mL of organic pollutant wastewater containing acid orange 7 (10 mg / L-50 mg / L), methylene blue (10 mg / L-50 mg / L), ciprofloxacin (10 mg / L-50 mg / L), and rhodamine B (10 mg / L-50 mg / L), 50 mg of the iron-based heterogeneous Fenton catalyst (12% FeP) prepared in Example 1 was added respectively. The adsorption equilibrium experiment was first carried out in the dark, and then H2O2 was added respectively to make the H2O2 concentration in the wastewater 100 mg / L to start the degradation reaction. The change of pollutant concentration in the wastewater with degradation time ( Figure 2 ):

[0063] Acid Orange 7 (AO7): 1 mL of sample was taken at 2 min, 5 min, 8 min, 10 min, 15 min, and 20 min, and the pollutant concentration was measured after filtering to remove the catalyst;

[0064] Methylene Blue (MB): 1 mL of sample was taken at 2 min, 5 min, 8 min, 10 min, 15 min, and 20 min, and the pollutant concentration was measured after filtering to remove the catalyst;

[0065] Ciprofloxacin (CIP): 1 mL of sample was taken at 5 min, 10 min, and 20 min, and the pollutant concentration was measured after filtering to remove the catalyst;

[0066] Rhodamine B (RhB), 1 mL of sample was taken at 2 min, 5 min, 8 min, 15 min, 30 min, and 60 min, and the pollutant concentration was measured after filtering to remove the catalyst;

[0067] Iron-based heterogeneous Fenton catalyst (Sch / FeP) is used to degrade organic wastewater. The Schrödinger mineral of the catalyst contains SO 2- 4 structure, which can be oxidized by OH in water - Substitution, while releasing H + Even if the initial pH value is neutral, the pH after the reaction can be stabilized in the most suitable pH range for Fenton reaction (3.0-3.6). Therefore, the initial organic wastewater does not need to adjust the pH value, which is more conducive to the application of actual wastewater treatment.

[0068] Comparative Example 2

[0069] The application of the iron phosphide catalyst (FeP) in this comparative example is basically the same as that in Example 4, except that:

[0070] The iron-based heterogeneous Fenton catalyst prepared in Example 1 was replaced with an iron phosphide catalyst.

[0071] Comparative Example 3

[0072] The application of the Schmidt mineral catalyst (Sch) in this comparative example is basically the same as that in Example 4, except that:

[0073] The iron-based heterogeneous Fenton catalyst prepared in Example 1 was replaced with a Schreiterite catalyst.

[0074] By Example 4, Comparative Examples 2-3 and Figure 2It can be seen that the iron-based heterogeneous Fenton catalyst shows a higher pollutant degradation rate than the iron phosphide and Schmertzite catalysts. As the degradation reaction proceeds, the value of C / C0 (C is the pollutant concentration measured by sampling at different time points, and C0 is the initial concentration of the pollutant) gradually decreases, and the degradation rate gradually increases. For the pollutants Acid Orange 7, Methylene Blue and Ciprofloxacin, the degradation rate reaches 100% after 5 minutes of degradation, and for the pollutant Rhodamine B, the degradation rate reaches 100% after 60 minutes of degradation.

[0075] Example 5

[0076] The application of an iron-based heterogeneous Fenton catalyst (Sch / FeP) of this embodiment comprises the following steps:

[0077] 50 mg of the iron-based heterogeneous Fenton catalyst (18% FeP) prepared in Example 2 was added to 50 mL of organic pollutant wastewater containing acid orange 7 (10 mg / L to 50 mg / L). An adsorption equilibrium experiment was first performed in the dark, and then H2O2 was added to make the H2O2 concentration in the wastewater 100 mg / L to start the degradation reaction. 1 ml of the degradation sample was taken at regular intervals, and the pollutant concentration was measured after filtering to remove the catalyst. When the degradation was carried out for 5 minutes, the degradation rate could be as high as 100%.

[0078] Example 6

[0079] The application of an iron-based heterogeneous Fenton catalyst (Sch / FeP) of this embodiment comprises the following steps:

[0080] 50 mg of the iron-based heterogeneous Fenton catalyst (10% FeP) prepared in Example 3 was added to 50 mL of organic pollutant wastewater containing acid orange 7 (10 mg / L to 50 mg / L). An adsorption equilibrium experiment was first performed in the dark, and then H2O2 was added to make the H2O2 concentration in the wastewater 100 mg / L to start the degradation reaction. 1 mL of the degradation sample was taken at regular intervals, and the pollutant concentration was measured after filtering to remove the catalyst. When the degradation was carried out for 5 minutes, the degradation rate could reach 90%.

[0081] Comparative Example 4

[0082] The application of an iron-based heterogeneous Fenton catalyst (Sch / FeP) in this comparative example comprises the following steps:

[0083] 50 mg of the iron-based heterogeneous Fenton catalyst (6% FeP) prepared in Comparative Example 1 was added to 50 mL of organic pollutant wastewater containing acid orange 7 (10 mg / L to 50 mg / L). An adsorption equilibrium experiment was first carried out in the dark, and then H2O2 was added to make the H2O2 concentration in the wastewater 100 mg / L to start the degradation reaction. 1 mL of the degradation sample was taken at regular intervals, and the pollutant concentration was measured after filtering to remove the catalyst. Degradation 5min, the degradation rate was 48%.

[0084] According to Example 5, Example 6 and Comparative Example 4, when the FeP loading in the iron-based heterogeneous Fenton catalyst is 10% to 18%, the degradation of organic pollutants can reach more than 90%.

[0085] Example 7

[0086] The application of an iron-based heterogeneous Fenton catalyst (Sch / FeP) of this embodiment comprises the following steps:

[0087] 50 mg of the iron-based heterogeneous Fenton catalyst (12% FeP) prepared in Example 1 was added to 50 mL of organic pollutant wastewater containing 50 mg / L of acid orange 7. An adsorption equilibrium experiment was first performed in the dark, and then H2O2 was added to make the H2O2 concentration in the wastewater 100 mg / L to start the degradation reaction. 1 mL of the degradation sample was taken at 2 min, 5 min, 8 min, 10 min, 15 min, and 20 min, respectively, and the Fe(II) dissolution, H2O2 consumption concentration, and H2O2 utilization rate were measured after filtering to remove the catalyst.

[0088] Reference for determination of H2O2 utilization: Lyu, L., Zhang, L., He, G., He, H. and Hu, C. (2017) Selective H2O2 conversion to hydroxyl radicals in the electron-rich area of ​​hydroxylated Cg-C3N4 / CuCo-Al2O3. J. Mater. Chem. A5(15), 7153-7164.

[0089] Comparative Example 5

[0090] The application of the iron phosphide catalyst in this comparative example is basically the same as that in Example 6, except that:

[0091] The iron-based heterogeneous Fenton catalyst prepared in Example 1 was replaced with an iron phosphide catalyst.

[0092] Comparative Example 6

[0093] The application of the Schmidt mineral catalyst in this comparative example is basically the same as that in Example 6, except that:

[0094] The iron-based heterogeneous Fenton catalyst prepared in Example 1 was replaced with a Schreiterite catalyst.

[0095] From Example 7, Comparative Examples 5-6 and Figure 3 b It can be seen that within the same degradation time, the amount of Fe(II) dissolved in the solution degraded using the iron-based heterogeneous Fenton catalyst is the highest, because the Fe in the FeP of the iron-based heterogeneous Fenton catalyst has a partial positive charge (Fe δ+ ,0<δ+<2), P in FeP has a partial negative charge (P δ- ,-1<δ-<0), Fe on the catalyst structure δ+ and P δ- It can provide electrons for Fe(III) reduction, accelerate iron cycle and Fe(II) regeneration performance. During the degradation process, the dissolved Fe(II) will be converted into Schroeder mineral, and the dissolution and conversion of Fe(II) will reach a dynamic balance, making the entire reaction system more stable.

[0096] Depend on Figure 3 It can be seen from a that in the same degradation time, the concentration of H2O2 in the solution degraded by the iron-based heterogeneous Fenton catalyst decreased the most, indicating that the most H2O2 was consumed in the degradation reaction. At the same time, the utilization rate of the consumed H2O2 reached 100%, because the iron-based heterogeneous Fenton catalyst dissolved more Fe(II) in the heterogeneous Fenton reaction, and the electron-rich P δ- It can also serve as an additional active site to activate H2O2 to produce reactive free radicals (such as ·OH), and the two together improve the utilization rate of H2O2.

[0097] Example 8

[0098] The application of an iron-based heterogeneous Fenton catalyst (Sch / FeP) of this embodiment comprises the following steps:

[0099] 30 mg of the iron-based heterogeneous Fenton catalyst (18% FeP) prepared in Example 2 was added to 50 mL of organic pollutant wastewater containing acid orange 7 (50 mg / L). An adsorption equilibrium experiment was first performed in the dark, and then H2O2 was added to make the H2O2 concentration in the wastewater 50 mg / L to start the degradation reaction. 1 mL of the degradation sample was taken at regular intervals, and the pollutant concentration was measured after filtering to remove the catalyst. When the degradation was carried out for 5 minutes, the degradation rate could reach 90%.

[0100] Example 9

[0101] The application of an iron-based heterogeneous Fenton catalyst (Sch / FeP) of this embodiment comprises the following steps:

[0102] 60 mg of the iron-based heterogeneous Fenton catalyst (18% FeP) prepared in Example 2 was added to 50 mL of organic pollutant wastewater containing acid orange 7 (50 mg / L). An adsorption equilibrium experiment was first performed in the dark, and then H2O2 was added to make the H2O2 concentration in the wastewater 300 mg / L to start the degradation reaction. 1 mL of the degradation sample was taken at regular intervals, and the pollutant concentration was measured after filtering to remove the catalyst. When the degradation was carried out for 5 minutes, the degradation rate could be as high as 100%.

[0103] Comparative Example 7

[0104] The application of an iron-based heterogeneous Fenton catalyst (Sch / FeP) in this comparative example comprises the following steps:

[0105] 30 mg of the iron-based heterogeneous Fenton catalyst (18% FeP) prepared in Example 2 was added to 50 mL of organic pollutant wastewater containing acid orange 7 (50 mg / L). An adsorption equilibrium experiment was first performed in the dark, and then H2O2 was added to make the H2O2 concentration in the wastewater 25 mg / L to start the degradation reaction. 1 mL of the degradation sample was taken at regular intervals, and the pollutant concentration was measured after filtering to remove the catalyst. When the degradation was carried out for 5 minutes, the degradation rate reached 58%.

[0106] It can be seen from Example 5, Examples 8-9 and Comparative Example 7 that when the iron-based heterogeneous Fenton catalyst degrades organic pollutants, the concentration in the organic wastewater is 0.6g / L~1.2g / L, the concentration of hydrogen peroxide in the organic wastewater is 50mg / L~300mg / L, and the degradation rate of organic pollutants can reach more than 90%.

[0107] The present application introduces iron phosphide in the process of chemical synthesis of Schmidt mineral to prepare an iron-based heterogeneous Fenton catalyst. The loading of FeP can significantly accelerate the Fe(II) / Fe(III) conversion, increase iron circulation, increase Fe(II) regeneration, and improve the catalytic performance of the iron-based heterogeneous Fenton catalyst by improving the H2O2 utilization rate and Fe(II) regeneration performance. At the same time, the unique sulfate structure of Schmidt mineral can provide an acidic reaction environment. The use of this catalyst for heterogeneous Fenton reaction to degrade organic wastewater can, on the one hand, quickly degrade a variety of organic pollutants in the water, with a degradation rate of more than 90%; on the other hand, the catalyst can drive excellent Fenton catalytic performance without adjusting the initial pH, and has good application prospects in the field of water treatment.

[0108] The above-mentioned embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present invention. It should be pointed out that, for a person skilled in the art, several modifications, improvements and substitutions can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the attached claims.

Claims

1. An iron-based heterogeneous Fenton catalyst, characterized in that: The catalyst comprises iron phosphide and Schroederite; calculated by mass ratio, the loading ratio of the iron phosphide on the catalyst is 10% to 18%.

2. An iron-based heterogeneous Fenton catalyst according to claim 1, characterized in that: Calculated by mass ratio, the loading ratio of the iron phosphide on the catalyst is 12% to 18%.

3. An iron-based heterogeneous Fenton catalyst according to any one of claims 1 or 2, characterized in that: The catalyst further comprises hydrogen peroxide; calculated by mass ratio, the hydrogen peroxide accounts for 4% to 33% of the catalyst.

4. A method for preparing an iron-based heterogeneous Fenton catalyst, characterized in that: The following steps are involved: S1. Adding iron phosphide to pure water to obtain an iron phosphide suspension; S2. Adding ferrous sulfate and / or ferrous sulfate hydrate to the iron phosphide suspension, and after the reaction, obtaining a precipitate; S3. collecting the precipitate, washing, and freeze-drying to obtain the iron-based heterogeneous Fenton catalyst; Calculated by mass ratio, the loading ratio of the iron phosphide on the catalyst is 10% to 18%.

5. The method for preparing an iron-based heterogeneous Fenton catalyst according to claim 4, characterized in that: The hydrate of ferrous sulfate is ferrous sulfate heptahydrate.

6. The method for preparing an iron-based heterogeneous Fenton catalyst according to claim 5, characterized in that: The mass ratio of the ferrous sulfate heptahydrate to the iron phosphide is 11-28:

1.

7. A method for preparing an iron-based heterogeneous Fenton catalyst according to any one of claims 4 to 6, characterized in that: In step S1, the suspension is prepared by ultrasonic dispersion; in step S2, the reaction is carried out in a constant temperature shaker.

8. An application of an iron-based heterogeneous Fenton catalyst, characterized in that: The iron-based heterogeneous Fenton catalyst described in any one of claims 1 to 3 is applied to the treatment of organic wastewater; or the iron-based heterogeneous Fenton catalyst prepared by the method described in any one of claims 4 to 6 is applied to the treatment of organic wastewater.

9. The use of an iron-based heterogeneous Fenton catalyst according to claim 8, characterized in that: Before using the iron-based heterogeneous Fenton catalyst to treat the organic wastewater, it is not necessary to adjust the pH value of the organic wastewater.

10. Use of an iron-based heterogeneous Fenton catalyst according to any one of claims 8 or 9, characterized in that: The catalyst is the catalyst in claim 1 or 2, and the amount thereof added to the organic wastewater is 0.6 g / L to 1.2 g / L; or the catalyst is the catalyst in claim 3, and the amount thereof added to the organic wastewater is 0.605 g / L to 1.5 g / L.

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