Composite filter material and preparation method thereof

Abstract

The present invention relates to the field of filter material technology, and in particular to a composite filter material and a preparation method thereof. The preparation method of the composite filter material comprises the following steps: taking boron nitride powder and calcining it to obtain pretreated boron nitride powder; adding phytic acid, 2-cyano-imino-1,3-thiazole, and Zn(NO3)2·6H2O to an ethanol aqueous solution, adding the pretreated boron nitride powder and stirring, and then performing a heating reaction to obtain modified boron nitride; adding the modified boron nitride to the ethanol aqueous solution to obtain a mixed solution; impregnating a polytetrafluoroethylene needle-punched felt filter material in the mixed solution, and repeating the impregnation-drying step 2-5 times after drying to obtain a filter material loaded with modified boron nitride; impregnating the filter material loaded with modified boron nitride in a mixed solution of manganese nitrate, cerium nitrate, and iridium nitrate, taking it out and drying it to obtain a composite filter material. The obtained filter material has a high removal effect on dioxins.

Description

Technical Field

[0001] The present invention relates to the technical field of filter materials, in particular to a composite filter material and a preparation method thereof. Background Art

[0002] Industrial flue gases emitted by industries such as coal-fired power generation, steel, glass, cement, and waste incineration contain significant amounts of persistent organic pollutants. Among these, dioxins, known for their environmental pollution and health hazards, have drawn considerable attention. With the continuous improvement of environmental laws and regulations, not only are emission standards for conventional pollutants becoming increasingly stringent, but trace pollutants like dioxins are also being monitored. Therefore, developing effective technologies to control dioxin emissions and ensure compliance with emission standards is crucial for both environmental protection and human health.

[0003] In the field of flue gas treatment, bag filters are widely used due to their efficient particle capture capabilities. The core component of these filters is the filter media. In recent years, research has shifted towards combining metal catalysts with filter media to develop composite filter media capable of simultaneously removing dioxins and particulate matter from flue gas. However, these composite filter media suffer from issues such as low catalyst efficiency. Against this backdrop, the present invention provides a composite filter media capable of efficiently removing dioxins and a method for its preparation. Summary of the Invention

[0004] In order to overcome the deficiencies of the prior art, one of the objects of the present invention is to provide a method for preparing a composite filter material, which is simple and easy to practice.

[0005] A second object of the present invention is to provide a composite filter material having a high dioxin removal effect.

[0006] One of the purposes of the present invention is achieved by the following technical solution:

[0007] A method for preparing a composite filter material comprises the following steps:

[0008] (1) Preparation of modified boron nitride

[0009] Boron nitride powder is calcined to obtain pretreated boron nitride powder; phytic acid, 2-cyanoimino-1,3-thiazole, and Zn(NO3)2·6H2O are added to an ethanol aqueous solution, and the pretreated boron nitride powder is added and stirred, followed by heating for reaction. After the reaction is completed, the solution is filtered, washed, and dried to obtain modified boron nitride;

[0010] (2) Preparation of filter material loaded with modified boron nitride

[0011] The modified boron nitride of step (1) is added to an ethanol aqueous solution to obtain a mixed solution; a polytetrafluoroethylene needle-punched felt filter material is immersed in the mixed solution, taken out and dried, and then the immersion-drying step is repeated 2-5 times to obtain a filter material loaded with modified boron nitride;

[0012] (3) Preparation of composite filter material

[0013] The filter material loaded with modified boron nitride in step (2) is immersed in a mixed solution of manganese nitrate, cerium nitrate and iridium nitrate, taken out and dried at 85-100°C for 2-3 hours, and then dried at 180-220°C for 18-24 hours to obtain the composite filter material.

[0014] Furthermore, the mass ratio of phytic acid, 2-cyanoimino-1,3-thiazole, Zn(NO3)2·6H2O, and pretreated boron nitride powder in step (1) is (2.5-3): (0.2-0.3): (0.05-0.1): 0.5; and the concentration of the ethanol aqueous solution is 50-60%.

[0015] Furthermore, the stirring time in step (1) is 2-3 hours; the temperature of the heating reaction is 200-210° C., and the heating reaction time is 4-6 hours.

[0016] Furthermore, the calcination temperature in step (1) is 800-900° C., and the calcination time is 5-6 hours.

[0017] Furthermore, the concentration of metal ions in the mixed solution of manganese nitrate, cerium nitrate and iridium nitrate in step (3) is 0.5-1 mol / L, and the molar ratio of manganese ion, cerium ion and iridium ion is (3-10): (1-5):1.

[0018] Furthermore, the immersion time in step (3) is 0.5-1.5h.

[0019] Furthermore, the solid content of the mixed solution in step (2) is 15-20%; and the concentration of the ethanol aqueous solution is 50-60%.

[0020] Furthermore, the immersion time in step (2) is 1-2 hours.

[0021] The second object of the present invention is achieved by adopting the following technical solution:

[0022] A composite filter material is prepared by adopting the preparation method of the composite filter material.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention provides a method for preparing a composite filter material, which is simple and easy to practice. The removal effect of the composite filter material prepared by the above preparation method on dioxins was tested and it was found that the modified boron nitride and the manganese-cerium-iridium ternary metal catalyst loaded in the composite filter material can form an "adsorption-degradation" cycle, and the combination of the two can significantly improve the removal effect of the filter material on dioxins. First, the coordination effect of phytic acid and 2-cyanoimino-1,3-thiazole makes a large amount of Zn 2+ The zinc ions in the modified boron nitride have a strong affinity for the fluorine atoms in the PTFE needled felt filter media, enabling uniform deposition of the modified boron nitride on the PTFE needled felt filter media. Furthermore, the introduction of phytic acid and 2-cyanoimido-1,3-thiazole increases the number of active groups on the boron nitride surface, such as phosphate and cyano groups. These groups not only serve as loading sites for the metal catalyst but also bind to the aromatic ring structure of dioxins through π-π interactions or hydrogen bonds, enhancing the physical and chemical adsorption efficiency of dioxins. The supported manganese, cerium, and iridium ternary metal catalyst efficiently degrades dioxins through the synergistic catalytic action of the three elements. The combined action of these three elements, through the adsorption-degradation process, endows the composite filter media with excellent dioxin removal performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is an infrared spectrum of the modified boron nitride prepared in Example 1 of the present invention;

[0026] Figure 2 Schematic diagram of the homemade catalytic degradation experimental device;

[0027] Reference numerals:

[0028] 1 is a dioxin generation source unit, 11 is a micro-injection pump, 12 is an atomizer, 13 is an airflow preheating section, 14 is a flow meter, 2 is a catalytic degradation unit, 21 is a sample to be tested, 22 is a reactor, 23 is a tubular furnace, 3 is an exhaust gas collection unit, 31 is an XAD-2 resin, and 32 is a toluene washing bottle. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, without conflict, the embodiments described below or the technical features can be arbitrarily combined to form new embodiments. Specific conditions not specified in the embodiments are carried out according to conventional conditions or conditions recommended by the manufacturer. All reagents or instruments used are conventional products obtained from commercial channels unless otherwise specified.

[0030] 1. Example

[0031] Example 1

[0032] This embodiment provides a method for preparing a composite filter material, and the specific preparation process is as follows:

[0033] (1) Preparation of modified boron nitride

[0034] Boron nitride powder was calcined in a muffle furnace at 800°C for 6 hours to obtain pretreated boron nitride powder; phytic acid, 2-cyanoimino-1,3-thiazole, Zn(NO3)2·6H2O, and pretreated boron nitride powder were added to a 50% ethanol aqueous solution in a mass ratio of 2.5:0.2:0.05:0.5, and the pretreated boron nitride powder was added and stirred for 2 hours. The reaction solution was transferred to an autoclave and then heated at 200°C for 6 hours. After the reaction was completed, the solution was filtered, the solid was collected, washed with deionized water three times, and then dried at 80°C for 5 hours to obtain modified boron nitride.

[0035] (2) Preparation of filter material loaded with modified boron nitride

[0036] The modified boron nitride prepared in step (1) was ultrasonically dispersed in a 50% ethanol aqueous solution to obtain a mixed solution having a solid content of 15%; a polytetrafluoroethylene needle-punched felt filter material was immersed in the mixed solution for 1 hour, dried at 80°C, and then the above-mentioned immersion-drying steps were repeated twice to obtain a filter material loaded with modified boron nitride;

[0037] (3) Preparation of composite filter material

[0038] A mixed solution of manganese nitrate, cerium nitrate and iridium nitrate is prepared, wherein the concentration of metal ions is 0.5 mol / L and the molar ratio of manganese ions, cerium ions and iridium ions is 3:1:1; the filter material loaded with modified boron nitride in step (2) is immersed in the mixed solution of manganese nitrate, cerium nitrate and iridium nitrate for 0.5 h, and vacuum filtered. The obtained filter material is first dried at 85°C for 3 h and then dried at 180°C for 24 h to obtain a composite filter material.

[0039] This embodiment also provides a composite filter material, which is prepared using the above preparation method.

[0040] Example 2

[0041] This embodiment provides a method for preparing a composite filter material, and the specific preparation process is as follows:

[0042] (1) Preparation of modified boron nitride

[0043] Boron nitride powder was calcined in a muffle furnace at 850°C for 5.5 hours to obtain pretreated boron nitride powder; phytic acid, 2-cyanoimino-1,3-thiazole, Zn(NO3)2·6H2O, and pretreated boron nitride powder were added to a 55% ethanol aqueous solution in a mass ratio of 2.6:0.25:0.06:0.5, and the pretreated boron nitride powder was added and stirred for 2.5 hours. The reaction solution was transferred to an autoclave and then heated at 205°C for reaction for 5 hours. After the reaction was completed, the solution was filtered, the solid was collected, washed with deionized water three times, and then dried at 80°C for 5 hours to obtain modified boron nitride.

[0044] (2) Preparation of filter material loaded with modified boron nitride

[0045] The modified boron nitride prepared in step (1) was ultrasonically dispersed in a 55% ethanol aqueous solution to obtain a mixed solution having a solid content of 18%; a polytetrafluoroethylene needle-punched felt filter material was immersed in the mixed solution for 1.5 h, dried at 80° C., and then the immersion-drying step was repeated three times to obtain a filter material loaded with modified boron nitride;

[0046] (3) Preparation of composite filter material

[0047] A mixed solution of manganese nitrate, cerium nitrate and iridium nitrate is prepared, wherein the concentration of metal ions is 0.7 mol / L and the molar ratio of manganese ions, cerium ions and iridium ions is 5:2:1; the filter material loaded with modified boron nitride in step (2) is immersed in the mixed solution of manganese nitrate, cerium nitrate and iridium nitrate for 1 hour, and vacuum filtered. The obtained filter material is first dried at 90°C for 2.5 hours and then dried at 200°C for 20 hours to obtain a composite filter material.

[0048] This embodiment also provides a composite filter material, which is prepared using the above preparation method.

[0049] Example 3

[0050] This embodiment provides a method for preparing a composite filter material, and the specific preparation process is as follows:

[0051] (1) Preparation of modified boron nitride

[0052] Boron nitride powder was calcined in a muffle furnace at 900°C for 5 hours to obtain pretreated boron nitride powder; phytic acid, 2-cyanoimino-1,3-thiazole, Zn(NO3)2·6H2O, and pretreated boron nitride powder were added to a 60% ethanol aqueous solution in a mass ratio of 3:0.3:0.1:0.5, and the pretreated boron nitride powder was added and stirred for 3 hours. The reaction solution was transferred to an autoclave and then heated at 210°C for 4 hours. After the reaction was completed, the solution was filtered, the solid was collected, washed with deionized water three times, and then dried at 80°C for 5 hours to obtain modified boron nitride.

[0053] (2) Preparation of filter material loaded with modified boron nitride

[0054] The modified boron nitride prepared in step (1) was ultrasonically dispersed in a 60% ethanol aqueous solution to obtain a mixed solution having a solid content of 20%; a polytetrafluoroethylene needle-punched felt filter material was immersed in the mixed solution for 2 h, dried at 80° C., and then the immersion-drying step was repeated 5 times to obtain a filter material loaded with modified boron nitride;

[0055] (3) Preparation of composite filter material

[0056] A mixed solution of manganese nitrate, cerium nitrate and iridium nitrate is prepared, wherein the concentration of metal ions is 1 mol / L and the molar ratio of manganese ions, cerium ions and iridium ions is 10:5:1; the filter material loaded with modified boron nitride in step (2) is immersed in the mixed solution of manganese nitrate, cerium nitrate and iridium nitrate for 1.5 hours, and vacuum filtered. The obtained filter material is first dried at 100°C for 2 hours and then dried at 220°C for 18 hours to obtain a composite filter material.

[0057] This embodiment also provides a composite filter material, which is prepared using the above preparation method.

[0058] 2. Comparative Example

[0059] Comparative Example 1

[0060] The difference between this comparative example and Example 1 is that:

[0061] Steps (1) and (2) were omitted, and the filter material loaded with modified boron nitride in step (3) was replaced with a polytetrafluoroethylene needle-punched felt filter material. The rest was the same as in Example 1.

[0062] This comparative example also provides a filter material, which is prepared using the above preparation method.

[0063] Comparative Example 2

[0064] The difference between this comparative example and Example 1 is that:

[0065] Omit the iridium nitrate in step (3), and the rest is the same as in Example 1.

[0066] This comparative example also provides a filter material, which is prepared using the above preparation method.

[0067] 3. Test example

[0068] Test Example 1

[0069] The modified boron nitride obtained in Example 1 was analyzed by infrared spectroscopy (FT-IR). The results are as follows: Figure 1 shown.

[0070] Figure 1 The following is the infrared spectrum of the modified boron nitride obtained in Example 1 of the present invention. 1 is the FT-IR spectrum of the pretreated boron nitride, and 2 is the FT-IR spectrum of the modified boron nitride. Figure 1 Curve 1 shows that the infrared spectrum of pretreated boron nitride is between 3200-3500 cm -1 The characteristic absorption peak of hydroxyl group appears at 1640 cm, indicating that the surface hydroxylation of boron nitride is successful. Compared with the pretreated boron nitride, the infrared spectrum of modified boron nitride has a peak at 1640 cm -1 The characteristic peak of NH in 2-cyanoimino-1,3-thiazole appears at 1000-1400 cm -1 The broadening of the peak observed at 580 cm is attributed to the presence of phosphate groups in phytic acid. -1 The Zn-O characteristic peak appears at 2+ Successful combination with pre-treated boron nitride.

[0071] Test Example 2

[0072] The dioxin removal effects of the filter materials obtained in Examples 1-3 and Comparative Examples 1-2 were tested. The specific testing process is as follows:

[0073] The filter materials obtained in Examples 1-3 and Comparative Examples 1-2 were placed in a self-made catalytic degradation experimental device (reference Figure 2 ) for testing.

[0074] Principle of the catalytic degradation experimental device: The dioxin source unit 1 includes a microinjection pump 11, an atomizer 12, and an airflow preheating section 13. The microinjection pump 11 is used to deliver the dioxin stock solution into the atomizer 12 at a uniform rate of 1 μL / min. The carrier gas (a mixture of N2 and O2, with O2 accounting for 10% by volume) carries the stock solution through the atomizer 12 through the flowmeter 14, where it is fully atomized and then enters the airflow preheating section 13. The dioxin stock solution is obtained from medical fly ash via Soxhlet extraction. The catalytic degradation unit 2 includes a reactor 22 containing the sample to be tested 21 and a tubular furnace 23, which provides a simulated flue gas temperature. The exhaust gas collection unit 3 includes XAD-2 resin 31 and a toluene wash bottle 32. The dioxin source system 1, the catalytic degradation reaction system 2, and the exhaust gas collection system 3 are tightly connected in sequence via pipes.

[0075] During the test, the sample 21 to be tested was placed in a tube furnace 23, and a carrier gas (O2 volume fraction of 10%) was introduced. The power supply of the reactor 22 was turned on, and the effective voltage was set to about 10 kV, the discharge frequency was 8-9 kHz, and the continuous discharge time was 30 min. The reaction temperature was set to 200 ° C, the gas flow rate was 500 mL / min, and the dioxin generation concentration was 5.5 ng / Nm 3 The dioxins in the tail gas are adsorbed and collected by XAD-2 resin 31 and toluene washing bottle 32, and then the two are mixed and pretreated using the US EPA1613 method. 13 C was used as an internal standard. The dioxin samples adsorbed on the filter media were pretreated individually using the US EPA1613 method to calculate the degradation efficiency.

[0076] Removal efficiency = (dioxin generation concentration - dioxin concentration collected by XAD-2 resin and toluene scrubber per unit time) / dioxin generation concentration × 100%; degradation efficiency = (dioxin generation concentration - dioxin concentration collected by XAD-2 resin and toluene scrubber per unit time - dioxin concentration adsorbed on filter media per unit time) / dioxin generation concentration × 100%. The test results are shown in Table 1.

[0077] Table 1

[0078]

[0079] As can be seen from Table 1, the filter material obtained in the present invention has a high dioxin removal and degradation effect, while the filter material obtained in Comparative Examples 1-2 has poor dioxin removal and degradation effects. These results demonstrate that the combination of modified boron nitride and the manganese-cerium-iridium ternary metal catalyst supported in the composite filter material can form an "adsorption-degradation" cycle, effectively removing dioxin pollutants.

[0080] Compared with Example 1, the dioxin removal effect of the filter material obtained in Comparative Example 1 without modified boron nitride was significantly reduced. The above results show that modified boron nitride can improve the dioxin removal effect of the filter material. Specifically, the coordination effect of phytic acid and 2-cyanoimino-1,3-thiazole makes a large amount of Zn 2+ The zinc ions in the modified boron nitride have a strong affinity for the fluorine atoms in the PTFE needled felt filter media, enabling uniform deposition of the modified boron nitride on the PTFE needled felt filter media. Furthermore, the introduction of phytic acid and 2-cyanoimido-1,3-thiazole increases the number of active groups on the boron nitride surface, such as phosphate and cyano groups. These groups not only serve as loading sites for metal catalysts but also bind to the aromatic ring structure of dioxins through π-π interactions or hydrogen bonds, enhancing the physical and chemical adsorption efficiency of dioxins, thereby improving the filter media's dioxin removal effectiveness.

[0081] Compared to Example 1, the filter material obtained in Comparative Example 2, which omitted iridium nitrate, exhibited significantly lower dioxin degradation efficiency. These results demonstrate that the supported manganese-cerium-iridium ternary metal catalyst enhances the filter material's dioxin degradation efficiency through the synergistic catalytic action of the three elements. Specifically, the supported manganese-cerium-iridium ternary metal catalyst enhances its oxidative capacity through electron coupling, significantly improving the filter material's dioxin degradation efficiency.

[0082] Test Example 3

[0083] The performance of the filter materials obtained in Examples 1-3 was tested, and the specific indicators and reference standards are as follows:

[0084] Waterproof grade: Tested in accordance with GB / T6719-2009, see Table 2 for the results;

[0085] Hydrolysis resistance: Tested according to GB / T6719-2009, the results are shown in Table 2;

[0086] Corrosion resistance: Tested with reference to GB / T6719-2009. The results are shown in Table 2.

[0087] Table 2

[0088]

[0089] From Table 2, it can be seen that the filter materials obtained in Examples 1-3 have excellent properties.

[0090] The above embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and replacements made by technicians in this field on the basis of the present invention fall within the scope of protection required by the present invention.

Claims

1. A method for preparing a composite filter material, characterized in that: The following steps are involved: (1) Preparation of modified boron nitride Boron nitride powder is calcined to obtain pretreated boron nitride powder; phytic acid, 2-cyanoimino-1,3-thiazole, and Zn(NO3)2·6H2O are added to an ethanol aqueous solution, and the pretreated boron nitride powder is added and stirred, followed by heating for reaction. After the reaction is completed, the solution is filtered, washed, and dried to obtain modified boron nitride; (2) Preparation of filter material loaded with modified boron nitride The modified boron nitride of step (1) is added to an ethanol aqueous solution to obtain a mixed solution; a polytetrafluoroethylene needle-punched felt filter material is immersed in the mixed solution, taken out and dried, and then the immersion-drying step is repeated 2-5 times to obtain a filter material loaded with modified boron nitride; (3) Preparation of composite filter material The filter material loaded with modified boron nitride in step (2) is immersed in a mixed solution of manganese nitrate, cerium nitrate and iridium nitrate, taken out and dried at 85-100°C for 2-3 hours, and then dried at 180-220°C for 18-24 hours to obtain the composite filter material.

2. The method for preparing the composite filter material according to claim 1, wherein: The mass ratio of phytic acid, 2-cyanoimino-1,3-thiazole, Zn(NO3)2·6H2O, and pretreated boron nitride powder in step (1) is (2.5-3): (0.2-0.3): (0.05-0.1): 0.5; the concentration of the ethanol aqueous solution is 50-60%.

3. The method for preparing the composite filter material according to claim 1, wherein: The stirring time in step (1) is 2-3 hours; the temperature of the heating reaction is 200-210°C, and the heating reaction time is 4-6 hours.

4. The method for preparing the composite filter material according to claim 1, wherein: The calcination temperature in step (1) is 800-900°C, and the calcination time is 5-6 hours.

5. The method for preparing the composite filter material according to claim 1, wherein: The concentration of metal ions in the mixed solution of manganese nitrate, cerium nitrate and iridium nitrate in step (3) is 0.5-1 mol / L, and the molar ratio of manganese ion, cerium ion and iridium ion is (3-10): (1-5):

1.

6. The method for preparing the composite filter material according to claim 1, wherein: The immersion time in step (3) is 0.5-1.5h.

7. The method for preparing the composite filter material according to claim 1, wherein: The solid content of the mixed solution in step (2) is 15-20%; the concentration of the ethanol aqueous solution is 50-60%.

8. The method for preparing the composite filter material according to claim 1, wherein: The immersion time in step (2) is 1-2 hours.

9. A composite filter material, characterized in that: The composite filter material is prepared by the preparation method of any one of claims 1 to 8.

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