Halogen-doped delta-MnO2 catalyst and application thereof

Abstract

The invention relates to a halogen-doped delta-MnO2 catalyst and an application thereof. The halogen-doped delta-MnO2 catalyst is prepared from raw materials containing potassium permanganate and ammonium halide, the application of the halogen-doped delta-MnO2 catalyst in activation of peroxymonosulfate comprises the following steps: firstly, adding the halogen-doped delta-MnO2 catalyst into bisphenol A raw water, uniformly stirring and mixing, then adding a peroxymonosulfate solution, and stirring and reacting to obtain a bisphenol A-removed water body. The halogen-doped delta-MnO2 catalyst has the advantages of being high in catalytic activity, capable of being recycled and beneficial to improving the water treatment efficiency of a PMS advanced oxidation technology, peroxymonosulfate can be efficiently activated so as to remove bisphenol A in water, operation is easy, energy is saved, and environment friendliness is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of water treatment, and in particular to a halogen-doped delta-MnO2 catalyst and application thereof. Background Art

[0002] In recent years, we have noticed the emergence of some new pollutants in water bodies, which are called emerging pollutants (CECs). They are environmentally persistent, bioaccumulative and biotoxic, and may pose a serious threat to the ecological environment and human health even at extremely low concentrations. Endocrine disruptors (EDCs) are one of the emerging pollutants. They are a class of chemicals that can interfere with the synthesis, secretion, transport, binding, action and metabolism of natural hormones in organisms. Since EDCs are usually present in extremely low concentrations in water bodies, their detection and removal become very difficult. Many EDCs have high environmental persistence and are not easy to decompose, so they can exist in water bodies for a long time, posing a potential threat to the environment and human health.

[0003] During the water treatment process, some EDCs, such as bisphenol A (BPA), may be converted into other forms of endocrine disruptors through chemical reactions. The hazards of these new forms may be more complex and difficult to predict. Bisphenol A is a typical environmental endocrine disruptor EDC. Due to its excellent physical and chemical properties, it is widely used in many fields such as plastic manufacturing, food packaging, and medical devices. It is an important organic chemical raw material. Due to its wide range of uses, bisphenol A easily enters the environment and is detected in water bodies. Therefore, there is an urgent need to find effective methods to solve the pollution problem of bisphenol A in the water environment.

[0004] Existing advanced oxidation technologies, especially the use of peroxymonosulfate (PMS), can activate PMS through homogeneous catalysts to effectively treat new pollutants such as antibiotics and hormones in water. However, the treatment efficiency of this method is relatively slow, and the homogeneous catalyst is not easy to recover, which may lead to secondary pollution of metal ions. Therefore, how to improve the treatment efficiency and solve the problem of catalyst recovery are key issues that need to be solved in current research and applications. Summary of the invention

[0005] In view of the shortcomings of the prior art, the first object of the present invention is to provide a halogen-doped δ-MnO2 catalyst, which has the advantages of high catalytic activity, recyclability, and is conducive to improving the water treatment efficiency of the PMS advanced oxidation technology.

[0006] The second object of the present invention is to provide an application of a halogen-doped δ-MnO2 catalyst, which has the advantages of efficiently removing bisphenol A in water, simple operation, energy saving and environmental protection.

[0007] To achieve the above first object, the present invention provides the following technical solutions: A halogen-doped delta-MnO2 catalyst is prepared from raw materials containing potassium permanganate and ammonium halide.

[0008] Furthermore, the molar ratio of potassium permanganate to ammonium halide is 1:1.00-1.50.

[0009] Furthermore, the ammonium halide is one or a combination of ammonium fluoride, ammonium chloride and ammonium bromide.

[0010] Furthermore, the preparation process includes reacting potassium permanganate and ammonium halide under high temperature conditions in an aqueous solvent, and performing post-treatment after the reaction to obtain a halogen-doped δ-MnO2 catalyst.

[0011] Furthermore, the preparation process includes dissolving potassium permanganate and ammonium halide in an aqueous solvent in advance, and heating and stirring in a water bath at 40-60° C. for 15-25 minutes.

[0012] Furthermore, the preparation process includes reacting potassium permanganate and ammonium halide in an autoclave with a polytetrafluoroethylene liner, controlling the reaction temperature to be 160-200° C., and the reaction time to be 20-30 hours.

[0013] Furthermore, the preparation process includes, after the reaction is completed, naturally cooling the reaction liquid, adding it to a centrifuge tube, continuously washing it with deionized water and anhydrous ethanol for multiple times, and then centrifuging to obtain a solid product, drying it at 70-90°C overnight, naturally cooling it, and grinding it for 25-35 minutes to obtain a halogen-doped δ-MnO2 catalyst.

[0014] To achieve the above first object, the present invention provides the following technical solutions: The invention discloses an application of a halogen-doped δ-MnO2 catalyst in activating peroxymonosulfate. The halogen-doped δ-MnO2 catalyst is firstly added into bisphenol A raw water, stirred and mixed, and then a peroxymonosulfate solution is added, stirred and reacted, and the halogen-doped δ-MnO2 catalyst and the bisphenol A-removed water are recovered.

[0015] Furthermore, the concentration of the bisphenol A raw water is controlled to be 8-12 mg / L.

[0016] Furthermore, the dosage of the halogen-doped δ-MnO2 catalyst in the bisphenol A raw water is controlled to be 100-500 mg / L.

[0017] Furthermore, the dosage of peroxymonosulfate in the bisphenol A raw water is controlled to be 0.1-0.5 mmol / L.

[0018] Furthermore, the peroxymonosulfate is potassium hydrogen persulfate.

[0019] In summary, the beneficial technical effects of the present invention are: Halogens such as fluorine, chlorine, and bromine in the ammonium halide of the catalyst of the present invention can be doped into potassium permanganate, thereby reducing the average oxidation state of Mn, increasing the content of Mn(III), and successfully improving the catalytic activity of the obtained catalyst. The catalyst is applied to the PMS advanced oxidation technology, thereby improving the efficiency of the PMS advanced oxidation technology in treating water bodies. The present invention further limits the molar ratio of potassium permanganate to ammonium halide, so that the halogen-doped δ-MnO2 catalyst can be better generated; The method comprises first dissolving potassium permanganate and ammonium halide in water, then heating in a water bath, and then adding the mixture into a high-temperature autoclave with a polytetrafluoroethylene liner for high-temperature reaction, and finally cooling, washing, centrifuging, drying, cooling, and grinding the reactants to obtain a catalyst with good catalytic activity. The present invention adds a catalyst to bisphenol A raw water, and then prepares a peroxymonosulfate solution. The Mn-O bond of Mn(III) in the catalyst is weaker than that of Mn(IV), which leads to a higher catalytic activity of Mn(III). In addition, Mn(III) activates peroxymonosulfate to form sulfate radicals, which have a higher redox potential, thereby improving the oxidation performance of peroxymonosulfate, thereby efficiently removing bisphenol A from bisphenol A raw water. The operation is simple and easy to implement, and no other reaction conditions need to be added. The method is energy-saving and environmentally friendly. The catalyst can also be recycled and reused, thereby reducing the operating cost. The present invention further limits the dosage of the catalyst and the peroxymonosulfate solution, so that the bisphenol A in the bisphenol A raw water can be removed better. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a graph showing the content of bisphenol A changing with time in comparative examples 1 to 3 and comparative example 5 of the present invention; wherein, δ-MnO2 is comparative example 5; F-δ-MnO2 is comparative example 1; Cl-δ-MnO2 is comparative example 2; and Br-δ-MnO2 is comparative example 3.

[0021] Figure 2 It is a graph showing the change in the content of bisphenol A over time in Comparative Example 6, Examples 1 to 3 and Comparative Example 4 of the present invention; wherein δ-MnO2+PMS is Comparative Example 6; F-δ-MnO2+PMS is Example 1; Cl-δ-MnO2+PMS is Example 2; Br-δ-MnO2+PMS is Example 3; and PMS is Comparative Example 4.

[0022] Figure 3These are SEM images of the catalysts of Examples 1 to 3 of the present invention, wherein (a) is δ-MnO2, (b) is F-δ-MnO2, (c) is Cl-δ-MnO2, and (d) is Br-δ-MnO2.

[0023] Figure 4 These are element mapping images of the catalysts of Examples 1 to 3 of the present invention, wherein (a) is F-δ-MnO2, (b) is Cl-δ-MnO2, and (c) is Br-δ-MnO2. DETAILED DESCRIPTION

[0024] In order to make the technical means, creative features, objectives and functions achieved by the present invention clearer and easier to understand, the present invention is further explained below in conjunction with the accompanying drawings and specific implementation methods.

[0025] Example 1: A halogen-doped δ-MnO2 catalyst disclosed in the present invention is made of raw materials including potassium permanganate and ammonium halide. The preparation process includes dissolving 1.58g potassium permanganate and 0.4629g ammonium halide (ammonium fluoride) in 90mL deionized water in advance, and heating and stirring in a water bath at 50°C for 20min; then transferring to an autoclave with a polytetrafluoroethylene liner for high-temperature reaction, controlling the reaction temperature to 180°C, and the reaction time to 24h; after the reaction, the reaction liquid is naturally cooled, and then added to a centrifuge tube, and continuously washed with deionized water and anhydrous ethanol for 3 times, and then centrifuged to obtain a solid product, which is dried overnight at 80°C, naturally cooled, and ground for 30min to obtain a halogen-doped δ-MnO2 catalyst.

[0026] The present invention also discloses the use of the above-mentioned halogen-doped δ-MnO2 catalyst in activating peroxymonosulfate. Among them, the above-mentioned unrecovered (recovery times 0) halogen-doped δ-MnO2 catalyst is first added to 10 mg / L bisphenol A raw water, the dosage of the halogen-doped δ-MnO2 catalyst is 100 mg / L, magnetic stirring is performed for 30 minutes, adsorption equilibrium is reached, and then peroxymonosulfate (potassium hydrogen persulfate) solution is added, the dosage of peroxymonosulfate is 0.5 mmol / L, magnetic stirring is performed for 60 minutes, and the halogen-doped δ-MnO2 catalyst and the water body from which bisphenol A is removed are recovered; in addition, the reaction liquid is filtered to obtain a filter residue, which is washed 3 times with anhydrous ethanol and deionized water, and vacuum dried at 60°C to recover the halogen-doped δ-MnO2 catalyst.

[0027] Bisphenol A removal rate detection: The content of bisphenol A in the bisphenol A raw water before treatment is recorded as a. After 60 minutes of treatment, the content of bisphenol A in the bisphenol A raw water is b. The removal rate c = (ab) / a * 100%. The higher the removal rate c, the better the treatment effect of the water body. The removal rate c is shown in Table 1 below.

[0028] Examples 2 to 10 are applications of a halogen-doped δ-MnO2 catalyst disclosed in the present invention. The difference from Example 1 is that the dosage of each component in the raw material and the removal rate c are shown in Table 1 below.

[0029] Comparative Examples 1 to 6 are applications of a halogen-doped δ-MnO2 catalyst disclosed in the present invention. The difference from Example 1 is that the dosage of each component in the raw material and the removal rate c are shown in Table 1 below.

[0030] Table 1 Potassium permanganate / g Ammonium halide / g Ammonium halide Recycling times Catalyst / mg / L Peroxymonosulfate / mmol / L Removal rate / % Example 1 1.58 0.4629 Ammonium fluoride 0 100 0.5 98.29 Example 2 1.58 0.6686 Ammonium chloride 0 100 0.5 99.52 Example 3 1.58 1.2243 Ammonium bromide 0 100 0.5 99.54 Example 4 1.58 0.4629 Ammonium fluoride 1 100 0.5 98.25 Example 5 1.58 0.6686 Ammonium chloride 1 100 0.5 99.50 Example 6 1.58 1.2243 Ammonium bromide 1 100 0.5 99.51 Example 7 1.58 0.4629 Ammonium fluoride 0 300 0.5 98.45 Example 8 1.58 0.4629 Ammonium fluoride 0 500 0.5 98.40 Example 9 1.58 0.4629 Ammonium fluoride 0 100 0.3 98.20 Example 10 1.58 0.4629 Ammonium fluoride 0 100 0.1 98.07 Comparative Example 1 1.58 0.4629 Ammonium fluoride 0 100 0 0.00 Comparative Example 2 1.58 0.6686 Ammonium chloride 0 100 0 0.00 Comparative Example 3 1.58 1.2243 Ammonium bromide 0 100 0 0.00 Comparative Example 4 1.58 0.4629 Ammonium fluoride 0 0 0.5 0.00 Comparative Example 5 1.58 0.6686 Ammonium chloride 0 0 0.5 0.00 Comparative Example 6 1.58 1.2243 Ammonium bromide 0 100 0.5 62.00 Combined with Table 1, Figure 2 , Examples 1 to 3 and Comparative Example 6, Examples 1 to 3 have significant removal effects on bisphenol A. At 60 minutes, bisphenol A is almost completely removed. It can be seen that potassium permanganate is doped with halogen using one of ammonium fluoride, ammonium chloride and ammonium bromide, and fluorine, chlorine and bromine in the ammonium halide are doped into potassium permanganate, which reduces the average oxidation state of Mn and increases the content of Mn (III), thereby successfully improving the catalytic activity of the obtained catalyst, thereby improving the efficiency and effect of the final water treatment.

[0031] Combination Figure 1 , Comparative Examples 1 to 3 and Comparative Example 5, it can be seen that the use of δ-MnO2 catalyst alone or halogen-doped δ-MnO2 catalyst has almost no adsorption effect on bisphenol A.

[0032] Combination Figure 2 Compared with Comparative Example 4, it can be seen that the use of peroxymonosulfate solution alone has almost no adsorption effect on bisphenol A.

[0033] Combining Table 1 with Examples 4 to 6, it can be seen that the use of the recovered halogen-doped δ-MnO2 catalyst to treat water still has a good treatment effect on the water, thereby achieving recycling and reuse and saving costs.

[0034] Combining Table 1, Example 1, and Examples 7-8, it can be seen that when the catalyst is added alone, when the catalyst dosage is 100-500 mg / L, the treatment effect on the water body is better.

[0035] Combining Table 1, Example 1, and Examples 9-10, it can be seen that when the peroxymonosulfate solution is added alone and the concentration of the peroxymonosulfate solution is 0.1-0.5 mmol / L, the treatment effect on the water body is better.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A halogen-doped δ-MnO2 catalyst, characterized in that: Made from raw materials including potassium permanganate and ammonium halide.

2. A halogen-doped δ-MnO2 catalyst according to claim 1, characterized in that: The molar ratio of potassium permanganate to ammonium halide is 1:1.00-1.

50.

3. The halogen-doped δ-MnO2 catalyst according to claim 1, characterized in that: The ammonium halide is one or a combination of ammonium fluoride, ammonium chloride and ammonium bromide.

4. The halogen-doped δ-MnO2 catalyst according to claim 1, characterized in that: The preparation process comprises the following steps: potassium permanganate and ammonium halide react under high temperature in a water solvent, and after the reaction is completed, a post-treatment is performed to obtain a halogen-doped delta-MnO2 catalyst.

5. A halogen-doped δ-MnO2 catalyst according to claim 4, characterized in that: The preparation process comprises dissolving potassium permanganate and ammonium halide in a water solvent in advance, and heating and stirring in a water bath at 40-60° C. for 15-25 minutes.

6. A halogen-doped δ-MnO2 catalyst according to claim 4, characterized in that: The preparation process comprises the following steps: potassium permanganate and ammonium halide are reacted in an autoclave with a polytetrafluoroethylene liner, the reaction temperature is controlled at 160-200° C., and the reaction time is controlled at 20-30 hours.

7. Use of a halogen-doped δ-MnO2 catalyst in activating peroxymonosulfate, characterized in that: First, add the unrecovered or severally recovered halogen-doped δ-MnO2 catalyst according to any one of claims 1 to 6 to the bisphenol A raw water, stir and mix, then add the peroxymonosulfate solution, stir and react, and recover the halogen-doped δ-MnO2 catalyst and the water from which bisphenol A is removed.

8. The use of a halogen-doped δ-MnO2 catalyst according to claim 7, characterized in that: The concentration of the bisphenol A raw water is controlled to be 8-12 mg / L.

9. The use of a halogen-doped δ-MnO2 catalyst according to claim 8, characterized in that: The dosage of the halogen-doped δ-MnO2 catalyst in the bisphenol A raw water is controlled to be 100-500 mg / L.

10. The use of a halogen-doped δ-MnO2 catalyst according to claim 8, characterized in that: The dosage of peroxymonosulfate in the bisphenol A raw water is controlled to be 0.1-0.5 mmol / L.

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