Phosphorus-modified Schwertmannite and preparation method and application thereof

Abstract

The invention discloses phosphorus-modified Schwertmannite as well as a preparation method and application thereof, and belongs to the field of water pollution treatment. The method comprises the following steps: adding H2O2 into an aqueous solution containing Fe < 2 + >, PO4 < 3-> and SO4 < 2->, oscillating for reaction, collecting precipitates, washing and drying to obtain the phosphorus modified Schwertmannite. SO4 < 2-> on the phosphorus-modified Schwertmannite can be subjected to substitution reaction with OH <-> in water to release H < + >, so that an acidic environment is provided for heterogeneous Fenton reaction. The phosphorus-modified Schwertmannite can also improve the regeneration performance of Fe < 2 + > and generate more hydroxyl radicals, so that the heterogeneous Fenton catalytic performance of the phosphorus-modified Schwertmannite is improved. The phosphorus-modified Schwertmannite has extremely high degradation efficiency on various organic pollutants, and has a good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of water pollution control, specifically relating to a phosphorus-modified Schiele mineral, its preparation method, and its application. Background Technology

[0002] Iron-based materials are the most widely studied solid catalysts in heterogeneous Fenton reactions, but most iron-based heterogeneous Fenton materials have the following drawbacks: (1) Fe 2+ / Fe 3+ (1) Low conversion rate; (2) Requires acidic reaction conditions. Therefore, rapid Fe... 2+ / Fe 3+ Conversion capacity and the provision of an acidic microenvironment are crucial for the application of iron-based catalysts in the Fenton reaction.

[0003] Existing technologies utilize electron-rich organic carbon materials (carbon nanotubes, graphene, etc.) and iron(III) oxide (Fe3O4) and iron phosphide (FeP), which possess high electron transfer capabilities, to accelerate iron cycling and enhance heterogeneous Fenton catalytic activity. However, the high cost and potential biotoxicity of organic carbon nanomaterials hinder their practical application. The preparation processes of Fe3O4 and FeP are hazardous and costly, making large-scale synthesis impractical. Furthermore, like traditional iron-based materials, Fe3O4 and FeP still require acidic conditions during the heterogeneous Fenton reaction and are prone to aggregation, failing to fully expose active sites.

[0004] Chinese invention patent application CN113385139A discloses a Sch,Fe8O8(OH) mineral prepared by alkali neutralization. 8-2x (SO4) x (x = 1 - 1.75)). SO4 in this Schiele mineral 2- The content is usually between 10% and 15%, of which 1 / 3 is SO4. 2- 2 / 3 of the SO4 is adsorbed on the Sch surface. 2- It exists within the internal tunnel structure. SO4 on the Sch surface. 2- It can be achieved through Fe8O8(OH) 8-2x (SO4) x +H₂O→Fe₈O₈(OH) 9-2x (SO4) x-1 +H + +SO4 2- The reaction lowers the solution pH, which is beneficial for the Fenton reaction. However, Schönbrunnes exhibit a long lag period during the Fenton reaction, resulting in a prolonged time required for pollutant degradation. This is primarily due to the fact that the main iron species in Schönbrunnes is Fe. 3+ The Fenton reaction is mainly Fe 2+The catalytic decomposition of H2O2 to generate hydroxyl radicals (·OH) results in low efficiency of the traditional Schiele mineral-catalyzed Fenton reaction. Summary of the Invention

[0005] 1. The problem to be solved

[0006] To address the problem of low efficiency in existing Fenton reaction catalysts, this invention provides a phosphorus-modified Sch / P mineral with high catalytic efficiency, its preparation method, and its applications.

[0007] 2. Technical Solution

[0008] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0009] This invention provides a method for preparing phosphorus-modified Schiele minerals, comprising the following steps: [The method involves] adding Fe... 2+ PO4 3- SO4 2- H2O2 was added to the aqueous solution of the substance. After the reaction was completed, the precipitate was collected, washed, and dried to obtain phosphorus-modified Schiele mineral.

[0010] Furthermore, the above-mentioned Fe 2+ PO4 3- SO4 2- The molar ratio of H2O2 is 0.67:(0.04-0.11):0.67:(0.5-2).

[0011] Furthermore, the above-mentioned Fe 2+ SO4 2- It comes from FeSO4·7H2O.

[0012] Furthermore, the aforementioned PO4 3- It comes from NaH2PO4·2H2O.

[0013] Furthermore, the hydrogen peroxide content mentioned above is 30% by mass.

[0014] Furthermore, the reaction conditions are as follows: 25-30℃ and 150-200rpm for 20-25h.

[0015] Furthermore, the reaction conditions were as follows: the reaction was carried out at 28°C and 180 rpm for 24 hours.

[0016] Furthermore, the above reaction is carried out in a multifunctional constant temperature shaker, which facilitates the control of temperature and rotation speed.

[0017] The present invention also provides a phosphorus-modified Sch / P mineral, which is prepared by the above-described method for preparing phosphorus-modified Sch / P mineral.

[0018] The present invention also provides the application of the above-mentioned phosphorus-modified Schiele mineral in the treatment of wastewater containing organic pollutants.

[0019] Furthermore, the above applications include adding phosphorus-modified Schiele minerals to wastewater containing organic pollutants.

[0020] Furthermore, the aforementioned phosphorus-modified Schiele mineral is used as a heterogeneous Fenton catalyst.

[0021] Furthermore, hydrogen peroxide also needs to be added in the above applications.

[0022] 3. Beneficial effects

[0023] Compared with the prior art, the advantages of this invention are as follows:

[0024] (1) The phosphorus-modified Sch / P mineral provided by this invention has P in the Sch / P structure carrying a partial negative charge (P0). δ- -1<δ - <0), which can accelerate Fe(II) regeneration; in addition, electron-rich P δ- It can also serve as an additional active site to activate H2O2 to produce ·OH.

[0025] (2) The phosphorus-modified Sch / P mineral (Sch / P) provided by this invention, when used as a heterogeneous Fenton catalyst for wastewater treatment, reduces the SO4 content on the Sch / P. 2- It will react with OH in the water - A substitution reaction occurs, releasing H. + This will provide an acidic environment for the heterogeneous Fenton reaction, eliminating the need for additional adjustment of solution acidity and making it more suitable for practical wastewater treatment applications.

[0026] (3) The phosphorus-modified Sch / P mineral (Sch / P) provided by this invention exhibits higher catalytic degradation activity for a variety of organic pollutants as a heterogeneous Fenton catalyst (see Figure 3 It has high degradation efficiency and good application prospects in wastewater treatment.

[0027] (4) The phosphorus-modified Sch / P mineral (Sch / P) provided by this invention, when used as a heterogeneous Fenton catalyst for wastewater treatment, has a lower cost (6.9 CNY / m³) compared to the previously studied Sch / FeP heterogeneous Fenton treatment of organic wastewater. 3 Compared to other methods, the Sch / P heterogeneous Fenton treatment used in this method is less expensive (4.9 CNY / m²). 3 ).

[0028] (5) The method for preparing phosphorus-modified Scherstein minerals provided by the present invention uses phosphates and other raw materials that are inexpensive and readily available. The preparation method is simpler, safer and more economical than other iron-based material-supported Scherstein minerals (such as Fe3O4 / Sch, Sch / FeP) catalysts, which is conducive to large-scale synthesis. Attached Figure Description

[0029] Figure 1 XRD patterns for Sch and Sch / P.

[0030] Figure 2 This is a distribution diagram of Fe, S, P, and O elements in Sch / P.

[0031] Figure 3 Homogeneous Fenton (Fe) 2+ Degradation effects of Sch and Sch / P heterogeneous Fenton phases on methylene blue (a), methyl orange (b), and acid orange 7 (c) pollutants.

[0032] Figure 4 For Sch and Sch / P in the heterogeneous Fenton reaction process Fe 2+ The concentration change graph.

[0033] Figure 5 EPR spectra of DMPO capturing ·OH in Sch and Sch / P heterogeneous Fenton. Detailed Implementation

[0034] The present invention will be further described below with reference to specific embodiments.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0036] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0037] As used herein, the term “about” is used to provide for the flexibility and imprecision associated with a given term, measure, or value. Those skilled in the art can readily determine the degree of flexibility for a particular variable.

[0038] Concentration, amount, and other numerical data may be presented in range format herein. It should be understood that such range format is used solely for convenience and brevity and should be flexibly interpreted to include not only the values ​​explicitly stated as the limits of the range, but also all individual values ​​or subranges encompassed within the range, as if each value and subrange were explicitly stated. For example, a range of values ​​from about 1 to about 4.5 should be interpreted to include not only the explicitly stated limits of 1 to 4.5, but also individual numbers (such as 2, 3, 4) and subranges (such as 1 to 3, 2 to 4, etc.). The same principle applies to ranges that describe only a single value, such as “less than about 4.5,” which should be interpreted to include all the aforementioned values ​​and ranges. Furthermore, this interpretation should apply regardless of the breadth of the range or characteristic described.

[0039] Example 1

[0040] This embodiment provides a method for preparing phosphorus-modified Sch / P mineral, the specific steps of which are as follows:

[0041] Add 0.3 g of NaH₂PO₄·2H₂O to 250 mL of pure water and stir until homogeneous. Then add 5.56 g of FeSO₄·7H₂O to the above NaH₂PO₄·2H₂O solution, with a mass ratio of FeSO₄·7H₂O to NaH₂PO₄·2H₂O of 18.5:1. Add 3 mL of 30% (mass fraction) H₂O₂ and place the mixture in a multifunctional constant temperature shaker (28℃, 180 rpm) for 24 h. Then collect the precipitate using a microporous membrane and wash with water to remove soluble impurities. Freeze-dry the collected product for later use.

[0042] From XRD ( Figure 1 ) and SEM-Mapping Figure 2 As can be seen, Sch / P possesses the characteristic peaks of Sch, and the elements Fe, S, P, and O are evenly distributed on Sch / P, indicating that P has been successfully modified onto Sch.

[0043] Determine the content of phosphorus (P) in the product:

[0044] 10 mg of Sch / P material was added to 5 mL of 1 M nitric acid solution to dissolve it until the material was completely dissolved. Then the solution was brought to a final volume of 25 mL. The concentration of P in the solution was determined by inductively coupled plasma optical emission spectrometry (ICP). The determination method was based on the method described in "Wang Junjie, Wang Qiaohuan. Determination of available phosphorus in soil by inductively coupled plasma optical emission spectrometry (ICP-OES) based on Olsen method [J]. Chinese Journal of Soil and Fertilizer, 2023(9):245-248".

[0045] The final P content in Sch / P was 3.9%.

[0046] Example 2

[0047] The Sch / P preparation steps are the same as in Example 1, except that the amount of NaH₂PO₄·2H₂O is 0.2 g, and the mass ratio of FeSO₄·7H₂O to NaH₂PO₄·2H₂O is 27.8:1. At this point, the P content in the Sch / P is 2.2%.

[0048] Example 3

[0049] The Sch / P preparation steps are the same as in Example 1, except that the amount of NaH2PO4·2H2O is 0.5g, and the mass ratio of FeSO4·7H2O to NaH2PO4·2H2O is 11.12:1. At this point, the P content in the Sch / P is 5.4%.

[0050] Example 4

[0051] This embodiment provides the application of phosphorus-modified Sch / P minerals in the treatment of wastewater containing organic pollutants, for heterogeneous Fenton catalytic degradation of organic pollutants.

[0052] Experimental group:

[0053] 50 mg of the Sch / P (3.9% P) catalyst prepared in Example 1 was added to a 50 mL solution containing 2.5 mg of each organic pollutant (MB, MO, and AO7 initial concentrations were 50 mg / L, initial pH of the solution = 8). An adsorption equilibrium experiment was first conducted in the dark (reaction was performed for 1 hour in a shaker at 28°C and 180 rpm). Then, 15 μL of 30% H2O2 was added to the above solution, and the reaction was initiated by shaking in a shaker at 28°C and 180 rpm. Samples of 1 mL were taken at 5, 10, 15, 20, 30, 40, 50, and 60 minutes, filtered to remove the catalyst, and the pollutant concentration was determined by spectrophotometry, referring to the article "Li T, Wang X, Chen Y, et al. Producing ·OH,·SO4". - and·O2 - in heterogeneous Fentonreaction induced by Fe3O4-modified schwertmannite[J]. Chemical Engineering Journal, 2020, 393. DOI: 10.1016 / j.cej.2020.124735.》.

[0054] Control group:

[0055] The catalytic degradation of pollutants was tested by replacing 50 mg of Sch / P catalyst with 50 mg of Sch (same mass) under the same conditions. The results are as follows: Figure 3 As shown. The preparation of Sch is referenced in "Regenspurg, S., Brand, A. and Peiffer, S. (2004) Formation and stability of schwertmannite in acidic mining lakes. Geochim. Cosmochim. Ac. 68(6), 1185-1197".

[0056] The 50 mg Sch / P catalyst was replaced with 0.45 mg FeSO4·7H2O (with the same iron dissolution rate as the experimental group), and the pollutant catalytic degradation experiment was conducted under the same conditions. The results are as follows: Figure 3 As shown. Homogeneous Fenton (Fe) 2+ The preparation of H2O2 is described in HLSheng, CLCho, Fenton process for treatment of desizing wastewater, Water Res., 31(1997)2050-2056.

[0057] from Figure 3 It can be seen that for the three pollutants, Sch / P degrades faster and has a higher final degradation rate than the other two groups (Sch and homogeneous Fenton). The degradation rate of many pollutants is as high as 99% or more in a short time (≤60 min).

[0058] Example 5

[0059] This embodiment provides the application of phosphorus-modified Sch / P minerals in the treatment of wastewater containing organic pollutants.

[0060] The heterogeneous Fenton catalytic degradation experimental procedure was the same as in Example 4. The difference was the addition of Sch / P (2.2% P) prepared in Example 2, with degradation samples taken at regular intervals to determine the pollutant concentration. When AO7 was the target pollutant, the degradation rate was 52% after 30 minutes of reaction.

[0061] Example 6

[0062] This embodiment provides the application of phosphorus-modified Sch / P minerals in the treatment of wastewater containing organic pollutants.

[0063] The heterogeneous Fenton catalytic degradation experimental procedure was the same as in Example 4. The difference was the addition of Sch / P (5.4% P) prepared in Example 3, with degradation samples taken at regular intervals to determine the pollutant concentration. When AO7 was the target pollutant, the degradation rate was 45% after 30 minutes of reaction.

[0064] Example 7

[0065] The catalytic degradation experiment was conducted in the same manner as in Example 4. 50 mg of the Sch / P (3.9% P) catalyst prepared in Example 1 was added to 50 mL of a 50 mg / L AO7 solution. An adsorption equilibrium experiment was first performed in the dark. Then, 15 μL of 30% H2O2 was added to the solution, and the mixture was shaken at 180 rpm to initiate the degradation reaction. Samples of 1 mL were taken at 5, 15, 30, 40, and 50 minutes, filtered to remove the catalyst, and then subjected to Fe... 2+ Dissolution concentration determination, Fe 2+ Concentrations were determined using the 1,10-phenanthroline colorimetric method, referring to Harvey AE, Smart JA and Amis ES (1955) Simultaneous spectrophotometric determination of Iron(II) and total iron with 1,10-phenanthroline. Anal. Chem. 27, 26-29. Simultaneously, samples reacted for 10 minutes were examined using electron paramagnetic resonance (EPR) to detect the generation of ·OH in the reaction system.

[0066] The results are as follows Figure 4 and Figure 5 As shown, compared with the Sch heterogeneous Fenton system, the Sch / P heterogeneous Fenton can generate more Fe. 2+ This facilitates the catalytic generation of large amounts of ·OH by H2O2, thereby accelerating the degradation of pollutants.

Claims

1. A method for preparing phosphorus-modified Schiele mineral, characterized in that, Includes the following steps: Towards Fe 2+ PO4 3- SO4 2- H2O2 was added to the aqueous solution of the substance. After the reaction was completed, the precipitate was collected, washed, and dried to obtain phosphorus-modified Schiele mineral.

2. The method for preparing phosphorus-modified Schiele mineral according to claim 1, characterized in that, The Fe 2+ PO4 3- SO4 2- The molar ratio of H2O2 is 0.67:(0.04-0.11):0.67:(0.5-2).

3. The method for preparing phosphorus-modified Schiele mineral according to claim 1, characterized in that, The Fe 2+ SO4 2- It comes from FeSO4·7H2O.

4. The method for preparing phosphorus-modified Schiele mineral according to claim 1, characterized in that, The PO4 3- It comes from NaH2PO4·2H2O.

5. The method for preparing phosphorus-modified Schiele mineral according to claim 1, characterized in that, The hydrogen peroxide has a mass fraction of 30%.

6. The method for preparing phosphorus-modified Schiele mineral according to claim 1, characterized in that, The reaction conditions are: 25-30℃, 150-200rpm for 20-25h.

7. A phosphorus-modified Schiele mineral, characterized in that, The phosphorus-modified Schiele mineral is prepared by the method described in any one of claims 1-6.

8. The application of the phosphorus-modified Schiele mineral of claim 7 in the treatment of wastewater containing organic pollutants.

9. The application of the phosphorus-modified Schiele mineral according to claim 8 in the treatment of wastewater containing organic pollutants, characterized in that, The phosphorus-modified Schiele mineral is used as a heterogeneous Fenton catalyst.

10. The application of the phosphorus-modified Schiele mineral according to claim 9 in the treatment of wastewater containing organic pollutants, characterized in that, The application also includes the addition of hydrogen peroxide.

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