A template-free nano-confined catalyst based on municipal sludge precursor, a preparation method and application thereof

Abstract

This invention provides a method for preparing a template-free nano-confined catalyst based on municipal sludge precursors. Compared with existing technologies, this invention utilizes sludge waste from urban wastewater treatment plants as raw material to prepare the confined catalyst, fully leveraging its complex characteristics of multi-component coexistence. It offers advantages such as no need to introduce additional templates, a simple preparation method, and low etchant usage. Furthermore, due to the waste nature of the raw material, large-scale, low-cost production of the confined catalyst can be achieved. In addition, when this confined catalyst is used for Fenton-like catalytic removal of pollutants in water, it exhibits high pollution load, significantly enhanced activity, and stability. This method is expected to advance the practical application of the nano-space confinement effect.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, and particularly relates to a template-free nano-confined catalyst based on municipal sludge precursor, its preparation method and application. Background Technology

[0002] A key task in catalysis research is to develop more efficient catalysts. One important approach is confined catalysis, where the microenvironment of the catalytic active site strongly restricts the physical and chemical states of the catalytic system, thereby effectively modulating catalytic performance. This method primarily works by altering the properties of the confined medium, catalyst geometry, and electronic properties to enhance mass transfer, active site exposure, and the utilization of active species. A crucial objective of confined catalysis is to find suitable supports that effectively confine active sites while simultaneously achieving high efficiency, stability, and sufficient exposure of the active sites. This requires support materials to possess stable structures, novel electronic properties, and highly exposed surfaces. This makes the synthesis of confined catalysts still a significant challenge.

[0003] Many confined catalytic materials have been developed to date, including zero-dimensional zeolite molecular sieves, one-dimensional carbon nanotube nanoreactors, and two-dimensional interlayer nanoreactors. However, due to limitations such as complex synthesis methods, the frequent need for external templates, high costs, and low yields, low-cost large-scale production and industrial applications are currently difficult to achieve. Municipal sewage sludge, due to its complexity and the coexistence of multiple carriers such as C, Si, and Al, offers the potential to form nanoscale confined spaces. Furthermore, its abundant heteroatoms and low metal content can be used for in-situ construction of active sites. Therefore, municipal sewage sludge provides a suitable precursor for the synthesis of confined catalytic materials, potentially enabling low-cost, industrial-scale production of nanoscale confined catalysts and advancing the practical application of nanoscale spatial confinement. Summary of the Invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide a template-free nano-confined catalyst based on municipal sludge precursor, its preparation method and application. The preparation method can realize the low-cost, template-free, large-scale synthesis of nano-confined catalysts, promote the practical application of the nano-space confinement effect, and realize catalytic processes with greater economic, social and environmental benefits.

[0005] This invention provides a method for preparing a template-free nano-confined catalyst based on municipal sludge precursor, comprising the following steps:

[0006] S1) The municipal sludge is dried and pulverized to obtain the precursor;

[0007] S2) The precursor is pyrolyzed to obtain a carbon-based material;

[0008] S3) After ball milling the carbon-based material, the silicon and aluminum oxides in the carbon-based material are removed by selective etching to obtain a template-free nano-confined catalyst.

[0009] Preferably, the drying temperature is 50℃~100℃.

[0010] Preferably, the pyrolysis temperature is 600℃~800℃; the pyrolysis time is 1~5h.

[0011] Preferably, the ball milling is a wet ball milling; the solvent for the wet ball milling is water and / or ethanol.

[0012] Preferably, the rotational speed of the ball mill is 300-520 r / min; the ratio of balls to material in the ball mill is 3:1 to 1:3.

[0013] Preferably, the etchant used for selective etching is selected from aqueous solutions of alkali metal hydroxides, ammonium fluoride solutions, or hydrofluoric acid; the concentration of the etchant is 0.1–5 mol / L; and the selective etching time is 0.4–48 h.

[0014] The present invention also provides a template-free nano-confined catalyst prepared by the above preparation method.

[0015] This invention also provides an application of the template-free nano-confined catalyst prepared by the above preparation method in the removal of pollutants from water by activated persulfate.

[0016] Preferably, the ratio of the template-free nanoconfined catalyst to persulfate is 0.2 g: (0.2-5) mmol.

[0017] Preferably, the contaminants include antibiotic contaminants and phenolic contaminants; the antibiotic contaminant is sulfamethoxazole; the phenolic contaminant is selected from nitrophenol and / or phenol; and / or,

[0018] The water in question is actual wastewater.

[0019] The actual COD value of the wastewater is 100-500 mg / L.

[0020] This invention provides a method for preparing a template-free nano-confined catalyst based on municipal sludge precursor, comprising the following steps: S1) drying and pulverizing municipal sludge to obtain a precursor; S2) pyrolyzing the precursor to obtain a carbon-based material; S3) ball milling the carbon-based material and selectively etching to remove silicon and aluminum oxides from the carbon-based material to obtain a template-free nano-confined catalyst. Compared with existing technologies, this invention utilizes sludge waste from urban wastewater treatment plants as raw material to prepare a confined catalyst, fully leveraging its complex characteristics of multi-component coexistence. It has advantages such as no need to introduce additional templates, simple preparation method, and low etchant usage. Furthermore, due to the waste nature of the raw material, large-scale, low-cost production of the confined catalyst can be achieved. In addition, when this confined catalyst is used for Fenton-like catalytic removal of pollutants in water, it exhibits high pollution load, significantly enhanced activity, and stability. It is expected to advance the practical application of the nano-space confinement effect. Attached Figure Description

[0021] Figure 1 A schematic diagram illustrating the preparation and application process of the template-free nano-confined catalyst based on municipal sludge precursor provided by this invention.

[0022] Figure 2 This is a high-resolution transmission electron microscope image of the template-free nano-confined catalyst obtained in Example 1 of the present invention;

[0023] Figure 3 The image shows the pore structure and specific surface area of ​​the template-free nanoconfined catalyst obtained in Example 1 of this invention.

[0024] Figure 4 This is a high-angle dark-field annular scanning transmission electron microscope image of the template-free nanoconfined catalyst obtained in Example 1 of this invention;

[0025] Figure 5 This is a comparison chart of the catalytic activity of the confined catalyst obtained in Example 1 of the present invention and the unconfined catalyst obtained in Comparative Example 1 in treating antibiotic wastewater (sulfamethoxazole).

[0026] Figure 6 This is a comparison chart of the catalytic activity of the confined catalyst obtained in Example 1 of the present invention and the unconfined catalyst obtained in Comparative Example 1 in treating phenol wastewater.

[0027] Figure 7 This is a comparison chart of the catalytic activity of the confined catalyst obtained in Example 1 of the present invention and the unconfined catalyst obtained in Comparative Example 1 in the deep treatment of actual wastewater (secondary effluent from comprehensive wastewater in Hefei Dongzhi Industrial Park).

[0028] Figure 8 This is a comparison chart showing the treatment capacity of the template-free nano-confined catalyst obtained in Example 1 of the present invention for phenol wastewater at different pH values.

[0029] Figure 9 This is a graph showing the reusability of the template-free nano-confined catalyst obtained in Example 1 of the present invention for treating phenol wastewater;

[0030] Figure 10 This is a comparison chart showing the catalytic activity of confined catalysts prepared with different etching agents in Examples 1, 6 and 7 of this invention for treating phenol wastewater. Detailed Implementation

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0032] This invention provides a method for preparing a template-free nano-confined catalyst based on municipal sludge precursor, comprising the following steps: S1) drying and pulverizing municipal sludge to obtain a precursor; S2) pyrolyzing the precursor to obtain a carbon-based material; S3) ball milling the carbon-based material and then selectively etching to remove silicon and aluminum oxides from the carbon-based material to obtain a template-free nano-confined catalyst.

[0033] See Figure 1 , Figure 1 This is a schematic diagram illustrating the preparation and application process of the template-free nano-confined catalyst based on municipal sludge precursor provided by the present invention.

[0034] This invention utilizes the complexity of municipal sewage sludge waste and its characteristic of multiple carriers coexisting, selectively etching the SiO₂ within it using strong alkalis, ammonium fluoride, or hydrofluoric acid as etching agents. x AlO x By combining components such as these, an in-situ nano-confined space is generated, enabling the simple and low-cost preparation of nano-confined catalysts without the need for external templates.

[0035] In this invention, there are no special restrictions on the source of any raw materials; they can be commercially available.

[0036] The municipal sludge is dried and pulverized to obtain the precursor. The municipal sludge can be any sludge produced by a regular municipal wastewater treatment plant, without any special restrictions. It can come from different process units of the wastewater treatment plant, such as return sludge or end-of-pipe dewatering sludge. The drying is preferably oven drying or natural air drying. When the drying method is oven drying, the drying temperature is preferably 50℃~100℃. After drying, the precursor is pulverized to obtain the precursor. The particle size of the pulverized material is preferably 100~300 mesh, more preferably 200 mesh.

[0037] The precursor is pyrolyzed to obtain a carbon-based material; the pyrolysis temperature is preferably 600℃~800℃, more preferably 650℃~750℃, and even more preferably 700℃; the pyrolysis heating rate is preferably 3~15℃ / min, more preferably 3~10℃ / min, and even more preferably 3~5℃ / min; the pyrolysis time is preferably 1~5h, more preferably 2~4h, and even more preferably 2~3h.

[0038] The carbon-based material is ball-milled; the ball milling is preferably wet ball milling; the solvent for the wet ball milling is preferably water and / or ethanol; the ratio of the solvent to the carbon-based material is preferably (0.5-2) mL:1 g, more preferably (1-1.5) mL:1 g; the ball milling speed is preferably 300-520 r / min; the ball-to-material ratio is preferably 3:1-1:3, more preferably 3:1-1:2, even more preferably 3:1-1:1, and most preferably 3:1-2:1; the ball milling time is preferably 2-12 h, more preferably 4-10 h, and even more preferably 5-6 h.

[0039] After ball milling, silicon-aluminum oxide in the carbon-based material is removed by selective etching to obtain a template-free nano-confined catalyst. In this invention, selective etching with an etchant is preferred to produce the optimal confined pore structure. The etchant used for selective etching can be any solution of resin capable of selectively etching silicon-aluminum oxide, which is not particularly limited. In this invention, an aqueous solution of alkali metal hydroxide, ammonium fluoride solution, or hydrofluoric acid is preferred. The aqueous solution of alkali metal hydroxide is preferably sodium hydroxide solution and / or potassium hydroxide solution. The concentration of the etchant is 0.1–5 mol / L, more preferably 0.4–5 mol / L, even more preferably 0.4–4 mol / L, and most preferably 0.5–2 mol / L. The selective etching time is preferably 0.4–48 h, more preferably 0.4–40 h, even more preferably 2–20 h, and most preferably 2–12 h.

[0040] This invention utilizes sludge waste from urban wastewater treatment plants as raw material to prepare a confined catalyst, fully leveraging its complex multi-component coexistence characteristics. It offers advantages such as requiring no additional template, a simple preparation method, and low etchant usage. Furthermore, due to the waste nature of the raw material, large-scale, low-cost production of the confined catalyst is possible. In addition, when this confined catalyst is used for Fenton-like catalytic removal of pollutants in water, it exhibits high pollutant load, significantly enhanced activity, and stability. This invention holds promise for advancing the practical application of the nanoscale spatial confinement effect.

[0041] This invention also provides a template-free nano-confined catalyst prepared by the above-described preparation method. Preferably, the pore volume ratio of the template-free nano-confined catalyst is 70% or more, more preferably 75% or more, and even more preferably 78% or more; in the embodiments provided by this invention, the pore volume ratio of the template-free nano-confined catalyst is specifically 80.1%.

[0042] This invention also provides an application of the template-free nano-confined catalyst prepared by the above preparation method in the removal of pollutants from water by activated persulfate.

[0043] The preferred ratio of the template-free nanoconfined catalyst to persulfate is 0.2 g:(0.2-5) mmol, more preferably 0.2 g:(0.5-4) mmol, even more preferably 0.2 g:(1-3) mmol, and most preferably 0.2 g:(1-2) mmol. In the embodiments provided by the present invention, the specific ratio of the template-free nanoconfined catalyst to persulfate is 0.2 g:1.95 mmol, 0.2 g:1.3 mmol, or 0.2 g:0.65 mmol. The persulfate can be any persulfate well known to those skilled in the art and is not particularly limited. In the present invention, it is preferred to include, but not limited to, permonosulfate (PMS) and / or perdisulfate (PDS).

[0044] According to the present invention, the pH value of the water containing pollutants is preferably 1 to 9; in the embodiments provided by the present invention, the pH value of the water containing pollutants is specifically 1.15, 4.05, 7.20 or 9.00.

[0045] The contaminants are preferably antibiotic contaminants and phenolic contaminants; the antibiotic contaminant is sulfamethoxazole; the phenolic contaminant is selected from nitrophenol and / or phenol.

[0046] According to the present invention, the water containing pollutants can also be actual wastewater; the COD value of the actual wastewater is preferably 100-500 mg / L, more preferably 200-300 mg / L; in the embodiments provided by the present invention, the secondary effluent of the comprehensive wastewater of Dongzhi Industrial Park (COD 265 mg / L) is used as an example for illustration.

[0047] According to the present invention, after the template-free nano-confined catalyst removes pollutants from water by activating persulfate, the template-free nano-confined catalyst can be recovered by filtration, washed with water and reused.

[0048] To further illustrate the present invention, the following detailed description, in conjunction with embodiments, provides a template-free nano-confined catalyst based on municipal sludge precursor, its preparation method, and its application.

[0049] All reagents used in the following examples are commercially available.

[0050] Example 1: Preparation of template-free nano-confined catalysts

[0051] (1) Collect sludge waste generated by sewage treatment plant, dry it at 60℃, crush it, and pass it through a 200-mesh sieve to obtain the precursor for preparing template-free nano-confined catalyst;

[0052] (2) The precursor obtained in step (1) was treated by pyrolysis for 3 hours (pyrolysis temperature 700℃, heating rate 5℃ / min) to obtain black carbon-based material;

[0053] (3) The black carbon-based material is moistened with an appropriate amount of ethanol (1 mL / g of black carbon-based material) and wet-milled for 6 hours. The rotation speed of the wet-milling is 300 rpm. The ball-to-material ratio of the wet-milling is 2:1.

[0054] (4) Collect the material treated in step (3) and selectively etch it with 0.5 mol / L hydrofluoric acid for 5 h to obtain a template-free nano-confined catalyst.

[0055] See Figure 2 , Figure 3 and Figure 4 . Figure 2 This is a high-resolution transmission electron microscope (TEM) image of the template-free nano-confined catalyst obtained in Example 1 of this invention; from Figure 2 As can be seen, the synthesized confined catalyst has a large number of micropores and mesopores in its confined pore structure. Figure 3 The image shows the pore structure and specific surface area characterization of the template-free nanoconfined catalyst obtained in Example 1 of this invention; from Figure 3 As can be seen, the increase in specific surface area and pore volume of the synthesized confined catalyst mainly comes from the confined pore structure below 30 nm. Figure 4 This is a high-angle dark-field annular scanning transmission electron microscope image of the template-free nanoconfined catalyst obtained in Example 1 of this invention; from Figure 4 As can be seen, the metal active sites are uniformly dispersed and confined around the confined pore structure, proving that a template-free nano-confined catalyst was successfully synthesized using sludge as a precursor.

[0056] Comparative Example 1: Preparation of Unconfined Catalysts

[0057] To highlight the crucial role of selective etching by a specific etchant in the synthesis of template-free nano-confined catalysts, Comparative Example 1 uses HCl acid washing (which cannot selectively etch silicon-aluminum oxides in sludge) instead of a selective etchant to synthesize an unconfined catalyst as a control, demonstrating the nano-space confinement effect of the template-free nano-confined catalyst of this invention. It is prepared according to the following steps:

[0058] (1) Collect sludge waste generated by sewage treatment plant, dry it at 60℃, crush it, and pass it through a 200-mesh sieve to obtain the precursor for preparing template-free nano-confined catalyst;

[0059] (2) The precursor obtained in step (1) was treated by pyrolysis for 3 hours (pyrolysis temperature 700℃, heating rate 5℃ / min) to obtain black carbon-based material;

[0060] (3) The black carbon-based material is moistened with an appropriate amount of ethanol (1 mL / g of black carbon-based material) and wet-milled for 6 hours. The rotation speed of the wet-milling is 300 rpm. The ball-to-material ratio of the wet-milling is 2:1.

[0061] (4) Collect the material treated in step (3) and wash it with 3 mol / L hydrochloric acid for 36 h to obtain the unconfined catalyst.

[0062] Example 2: Application of template-free nano-confined catalyst in the removal of antibiotic pollutants from water by activating persulfate

[0063] The template-free nano-confined catalyst obtained in Example 1 was added to a solution containing 50 mg / L sulfamethoxazole (pH 7.0) at a dosage of 0.2 g / L and ultrasonically dispersed. The solution was stirred at 700 rpm for 20 min to establish adsorption-desorption equilibrium. Subsequently, potassium persulfate (1.95 mM) was added to the solution. The stirring speed was maintained at 700 rpm. Over 92% of the sulfamethoxazole was removed within 5 min.

[0064] As a control, the same test was performed on the unconfined catalyst obtained in Comparative Example 1, and only 41% of sulfamethoxazole was removed within 5 minutes.

[0065] See Figure 5 , Figure 5 This is a comparison chart of the catalytic activity of the confined catalyst obtained in Example 1 of this invention and the unconfined catalyst obtained in Comparative Example 1 in treating antibiotic wastewater (sulfamethoxazole); from Figure 5 As can be seen from the above, under the same experimental conditions, the template-free nano-confined catalyst of the present invention exhibits far superior catalytic activity compared to the latter, and the confined catalyst of the present invention improves the reaction rate constant by two orders of magnitude compared to the unconfined catalyst.

[0066] Example 3: Application of template-free nano-confined catalyst in the removal of phenolic pollutants from water by activating persulfate

[0067] The template-free nano-confined catalyst obtained in Example 1 was added to a solution containing 60 mg / L phenol (pH 7.0) at a dosage of 0.2 g / L and ultrasonically dispersed. The solution was stirred at 700 rpm for 20 min to establish adsorption-desorption equilibrium. Subsequently, potassium persulfate (1.95 mM) was added to the solution, maintaining the stirring speed at 700 rpm. Phenol was 100% removed within 2 min, and TOC removal reached 71.2% within 20 min.

[0068] As a control, the same test was performed on the unconfined catalyst obtained in Comparative Example 1, and only 36% of phenol was removed within 2 minutes.

[0069] See Figure 6 , Figure 6 This is a comparison chart of the catalytic activity of the confined catalyst obtained in Example 1 of this invention and the unconfined catalyst obtained in Comparative Example 1 in treating phenol wastewater; from Figure 6 As can be seen from the above, under the same experimental conditions, the template-free nano-confined catalyst of the present invention exhibits far superior catalytic activity compared to the latter, and the confined catalyst of the present invention improves the reaction rate constant by two orders of magnitude compared to the unconfined catalyst.

[0070] Example 4: Application of template-free nano-confined catalyst for activating persulfate in actual industrial wastewater advanced treatment

[0071] The template-free nano-confined catalyst obtained in Example 1 was added to actual wastewater (secondary treatment effluent from the Hefei Dongzhi Industrial Park comprehensive wastewater treatment plant) with a COD of 265 mg / L (pH 7.5) at a dosage of 0.5 g / L and ultrasonically dispersed. The solution was stirred at 700 rpm for 20 min to establish pollutant adsorption-desorption equilibrium. Subsequently, potassium persulfate (3.25 mM) was added to the solution. The stirring speed was maintained at 700 rpm. Within 20 min, the COD in the wastewater could be removed by up to 72.3%.

[0072] As a control, the unconfined catalyst obtained in Comparative Example 1 was subjected to the same test, and the COD of the wastewater was only 47.2% removed within 20 minutes.

[0073] See Figure 7 , Figure 7 This is a comparison chart of the catalytic activity of the confined catalyst obtained in Example 1 of this invention and the unconfined catalyst obtained in Comparative Example 1 in the deep treatment of actual wastewater (secondary effluent from the comprehensive wastewater of Hefei Dongzhi Industrial Park); from Figure 7 As can be seen from the results, under the same experimental conditions, the template-free nano-confined catalyst of the present invention exhibits superior performance in actual wastewater treatment.

[0074] Example 5: Application of template-free nano-confined catalyst for the removal of pollutants from water by persulfate under different pH conditions

[0075] The template-free nano-confined catalyst obtained in Example 1 was added to solutions containing 20 mg / L phenol for removal. The solutions had pH values ​​of 1.15, 4.05, 7.20, and 9.00 (the pH was adjusted using 0.5 M NaOH and / or H₂SO₄). The catalyst dosage was 0.2 g / L, and the solution was ultrasonically dispersed. The mixture was stirred at 700 rpm for 20 min to establish adsorption-desorption equilibrium. Subsequently, 0.65 mM potassium persulfate was added to the solution. The stirring speed was maintained at 700 rpm. Under different pH conditions, over 99% of the phenol was removed within 2 min.

[0076] See Figure 8 , Figure 8 This is a comparison chart showing the treatment capacity of the template-free nano-confined catalyst obtained in Example 1 of this invention for phenol wastewater at different pH values; from Figure 8 As can be seen, the template-free nano-confined catalyst of the present invention has a wide pH range. Within the pH range of 1 to 9, more than 99% of phenol can be removed within 2 minutes.

[0077] Example 6: Preparation of template-free nano-confined catalysts

[0078] (1) Collect sludge waste generated by sewage treatment plant, dry it at 60℃, crush it, and pass it through a 200-mesh sieve to obtain the precursor for preparing template-free nano-confined catalyst;

[0079] (2) The precursor obtained in step (1) was treated by pyrolysis for 3 hours (pyrolysis temperature 650℃, heating rate 3℃ / min) to obtain black carbon-based material;

[0080] (3) The black carbon-based material is moistened with an appropriate amount of ethanol (1 mL / g of black carbon-based material) and wet-milled for 6 hours. The rotation speed of the wet-milling is 300 rpm. The ball-to-material ratio of the wet-milling is 3:1.

[0081] (4) Collect the material treated in step (3) and selectively etch it with 4 mol / L sodium hydroxide for 24 h to obtain a template-free nano-confined catalyst.

[0082] Example 7: Preparation of template-free nano-confined catalysts

[0083] (1) Collect sludge waste generated by sewage treatment plant, dry it at 60℃, crush it, and pass it through a 200-mesh sieve to obtain the precursor for preparing template-free nano-confined catalyst;

[0084] (2) The precursor obtained in step (1) was treated by pyrolysis for 3 hours (pyrolysis temperature 700℃, heating rate 5℃ / min) to obtain black carbon-based material;

[0085] (3) The black carbon-based material is moistened with an appropriate amount of ethanol (1 mL / g of black carbon-based material) and wet-milled for 6 hours. The rotation speed of the wet-milling is 300 rpm. The ball-to-material ratio of the wet-milling is 2:1.

[0086] (4) Collect the material treated in step (3) and selectively etch it for 5 hours with a 1 mol / L fluorine-containing solution (the concentration is calculated based on the fluorine content, and it is a mixed solution of hydrofluoric acid and ammonium fluoride with a molar ratio of 1:9) to obtain a template-free nano-confined catalyst.

[0087] Example 8: Application of template-free nano-confined catalyst for repeated use in the removal of phenolic pollutants from water by activated persulfate

[0088] The template-free nano-confined catalyst obtained in Example 1 was added to a solution (pH 7.0) targeting 20 mg / L phenol at a dosage of 0.2 g / L and ultrasonically dispersed. Potassium persulfate (0.65 mM) was added to the solution while stirring at 700 rpm. After reacting for 30 min, the catalyst was recovered by filtration through a 0.22 μm PVDF membrane, washed three times with deionized water, and then ultrasonically redispersed in a fresh solution targeting 20 mg / L phenol. Potassium persulfate (0.65 mM) was added to the solution while stirring at 700 rpm to begin the next reaction cycle. This process was repeated 8 times. In these 8 cycles, over 99% of the phenol was removed within 20 min.

[0089] See Figure 9 , Figure 9 The template-free nano-confined catalyst of the present invention demonstrates its reusability in treating phenol wastewater. As can be seen from the figure, the template-free nano-confined catalyst of the present invention exhibits good catalytic stability and reusability. In eight cycles of use without regeneration treatment, more than 99% of the phenol can be removed within 20 minutes.

[0090] Example 9: Application of template-free nano-confined catalysts prepared with different etching agents in the removal of phenolic pollutants from water by persulfate.

[0091] The template-free nano-confined catalysts obtained in Examples 1, 6, and 7 were added to solutions containing 20 mg / L phenol (pH 7.0) at a dosage of 0.2 g / L and ultrasonically dispersed. The solution was stirred at 700 rpm for 20 min to establish adsorption-desorption equilibrium. Subsequently, 0.65 mM potassium persulfate was added to the solution, maintaining the stirring speed at 700 rpm. Phenol was 100% removed within 40 seconds.

[0092] See Figure 10 , Figure 10 This is a comparison chart of the catalytic activity of confined catalysts prepared with different etching agents obtained in Examples 1, 6, and 7 of this invention for treating phenol wastewater; from Figure 10 As can be seen from the results, under the same experimental conditions, the confinement catalysts prepared by different etchants of the present invention can all remove phenol 100% efficiently within 40 seconds. However, among the confinement catalysts prepared by the three selective etchants, the confinement catalyst prepared by HF etching has the highest activity and can remove phenol 100% efficiently within 20 seconds.

[0093] In summary, the method for preparing template-free nano-confined catalysts based on municipal sludge precursors provided by this invention has the following advantages:

[0094] 1. This invention uses municipal sludge waste as the sole raw material and takes advantage of its complex characteristics of multiple carriers coexisting. Through selective etching with a specific etchant, a high-performance template-free nano-confined catalyst is synthesized. The method is simple, does not require the introduction of an external template, and uses a low amount of etchant.

[0095] 2. This invention uses sludge precursors to prepare template-free nano-confined catalysts. The abundant heteroatoms and low metal content in sludge can be used for in-situ construction of active sites.

[0096] 3. This invention uses sludge precursors to prepare template-free nano-confined catalysts. Due to the waste properties of the raw materials used, large-scale, low-cost production of confined catalysts can be achieved.

[0097] 4. By controlling the selective etching conditions of a specific etchant, this invention can achieve effective regulation of the nano-confined space and optimize the performance of template-free nano-confined catalysts.

[0098] 5. The template-free nano-confined catalyst of the present invention has excellent Fenton-like catalytic performance and exhibits a special process enhancement effect in environmental pollution remediation. It can be applied to the efficient, rapid and thorough removal of pollutants in water bodies. It has high catalytic stability, the material can be reused, strong anti-interference ability, wide pH range, low oxidant dosage, and significantly reduces the operating cost of water treatment processes, and has the potential for practical application.

[0099] 6. The synthesis method of this invention has a high catalyst yield and is easy to scale up. At the same time, the sludge waste is upgraded and recycled into a highly efficient template-free nano-confined catalyst, which can directly save a lot of sludge disposal costs for sewage treatment plants, resulting in significant economic benefits.

[0100] 7. The template-free nano-confined catalyst preparation technology of the present invention is simple, highly operable, and has significant effects and obvious economic benefits, and has broad industrial application prospects in the field of environmental pollution purification.

Claims

1. The application of a template-free nano-confined catalyst in the removal of pollutants from water by activated persulfate, characterized in that, The preparation method of the template-free nanoconfined catalyst includes the following steps: S1) The municipal sludge is dried and pulverized to obtain the precursor; S2) The precursor is pyrolyzed to obtain a carbon-based material; S3) After ball milling the carbon-based material, the silicon and aluminum oxides in the carbon-based material are removed by selective etching to obtain a template-free nano-confined catalyst; the etchant used for selective etching is selected from hydrofluoric acid; the concentration of the etchant is 0.1~5 mol / L; the selective etching time is 0.4~48 h; The template-free nanoconfined catalyst has a pore volume ratio of less than 30 nm of more than 70%. The contaminants include antibiotic contaminants and phenolic contaminants; the antibiotic contaminant is sulfamethoxazole; the phenolic contaminant is selected from phenol.

2. The application according to claim 1, characterized in that, The drying temperature is 50℃~100℃.

3. The application according to claim 1, characterized in that, The pyrolysis temperature is 600℃~800℃; the pyrolysis time is 1~5 h.

4. The application according to claim 1, characterized in that, The ball milling is a wet ball milling; the solvent for the wet ball milling is water and / or ethanol.

5. The application according to claim 4, characterized in that, The ball mill operates at a speed of 300-520 r / min; the ball-to-material ratio is 3:1 to 1:

3.

6. The application according to claim 1, characterized in that, The ratio of the template-free nanoconfined catalyst to persulfate is 0.2 g: (0.2~5) mmol.

7. The application according to claim 1, characterized in that, The water in question is actual wastewater. The actual COD value of the wastewater is 100~500 mg / L.

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