Preparation method and application of a trace H2O2-assisted ultrafast high-salt wastewater purification catalyst

Abstract

This invention discloses a method for preparing a catalyst for ultra-fast high-salt wastewater purification assisted by trace amounts of H2O2, belonging to the field of wastewater degradation catalyst preparation technology. The method includes the following steps: dispersing biomass silkworm excrement in deionized water, adding soluble copper salt, and stirring thoroughly to dissolve to obtain suspension A; adding tannic acid to suspension A, and stirring thoroughly to dissolve to obtain suspension B; adding urea to suspension B, stirring thoroughly to dissolve, evaporating the solvent, drying, and grinding to obtain an intermediate product; calcining the intermediate product in flowing nitrogen gas, and grinding again to obtain the final product. This invention uses a two-step synthesis method involving organic complexation reaction and calcination to prepare a catalyst with excellent catalytic degradation performance for organic pollutants in water, exhibiting high catalytic degradation capacity and extremely high salt tolerance.

Description

Technical Field

[0001] This invention relates to the field of wastewater degradation catalyst preparation technology, specifically to a method for preparing and applying a catalyst for ultra-fast high-salt wastewater purification assisted by trace amounts of H2O2. Background Technology

[0002] In aquatic systems, emerging pollutants (ECs) are causing increasing pollution, such as pharmaceutically active compounds like antibiotics and endocrine disruptors like bisphenol A (BPA), which can easily lead to similar or even more serious problems for aquatic organisms and human health. Particularly for highly alkaline wastewater (≥3.5%) generated by various industries such as chemical manufacturing and seawater desalination, traditional advanced oxidation processes have lost their effectiveness due to the rapid reaction of high concentrations of salt ions with free radicals, often accompanied by significant energy consumption. Research has found that heterogeneous catalysts containing cation-π interactions can exhibit highly efficient degradation of ECs with low oxidant consumption by enhancing interfacial electron-directed transfer, attributed to strong cation electrostatic forces. The strength of the cation-π interaction depends on the type of cation and the properties of the π system, indicating that the strength of the electrostatic field can be tuned by the surrounding environment. Notably, the interaction between cations / anions and the π system influences the strength of the cation-π interaction. Therefore, coordination of these substances with cations and the system in heterogeneous catalysts can produce different catalytic efficiencies by adjusting the strength of the cation-π electrostatic force. Therefore, developing a heterogeneous catalyst containing a cation-π system, utilizing the synergistic coordination of multiple components on the catalyst surface to induce charge rearrangement and generate greater electric field energy for ECs cracking, may be a breakthrough for achieving low-energy, high-efficiency, and high-salt wastewater purification. Summary of the Invention

[0003] To address the above problems, this invention provides a method for preparing and applying a catalyst for ultra-fast purification of high-salt wastewater assisted by trace amounts of H2O2.

[0004] The objective of this invention is achieved through the following technical solution:

[0005] The first aspect of this invention is to provide a method for preparing a catalyst for ultra-fast purification of high-salt wastewater assisted by trace amounts of H2O2, comprising the following steps:

[0006] (1) Disperse the biomass silkworm excrement in deionized water, add soluble copper salt, and stir thoroughly to dissolve to obtain suspension A;

[0007] (2) Add tannic acid to the suspension A, stir thoroughly to dissolve, and then obtain suspension B;

[0008] (3) Add urea to the suspension B, stir thoroughly to dissolve, evaporate the solvent, dry and grind to obtain the intermediate product;

[0009] (4) The intermediate product is calcined in flowing nitrogen gas and then ground again to obtain the final product.

[0010] In some preferred embodiments, the molar ratio of the biomass silkworm excrement to the soluble copper salt is 0.3-25 g / mM, more preferably 1.6-5 g / mM.

[0011] In some preferred embodiments, the mass ratio of the biomass silkworm excrement to the tannic acid is 0.5-10 g / g, more preferably 2.5-5 g / g.

[0012] In some preferred embodiments, the mass ratio of the biomass silkworm excrement to the urea is 0.06-5 g / g, more preferably 0.3-1 g / g.

[0013] In some preferred embodiments, the drying temperature in step (3) is 40-80°C and the drying time is 8-18 hours.

[0014] In some preferred embodiments, the calcination temperature is 500-900℃, the heating rate is 3-7℃ / min, and the holding time is 2-5h.

[0015] A second aspect of the present invention is to provide a trace H2O2-assisted ultra-fast high-salt wastewater purification catalyst, said catalyst being prepared by the aforementioned preparation method.

[0016] A third aspect of the present invention is to provide a trace amount of H2O2-assisted ultra-fast high-salt wastewater purification catalyst as a Fenton catalyst in the degradation of organic pollutants in water, wherein the catalyst and hydrogen peroxide are uniformly dispersed in water containing organic pollutants.

[0017] In some preferred embodiments, the organic pollutant includes one or more of bisphenol A, ciprofloxacin, tetracycline, diphenhydramine, 2,4-dichlorophenoxyacetic acid, and phenytoin.

[0018] The beneficial effects of this invention are as follows:

[0019] (1) The method of this invention employs a two-step synthesis approach. First, a simple organic complexation reaction is used, followed by a calcination method to prepare a catalyst with excellent catalytic degradation performance for organic pollutants in water. The catalyst's structure mainly consists of copper and graphene-like structures linked by Cu-NC and Cu-OC bonds and coated with zero-valent copper, forming a cation-π electrostatic force on the catalyst surface. During the catalytic degradation reaction, the synergistic coordination of ECs, H2O, and salts on the catalyst surface can induce charge rearrangement on the catalyst surface, enhancing the chemical adsorption of ECs and H2O and generating a stronger surface electric field energy. Only under low oxidant consumption conditions, the... The catalyst exhibits highly efficient catalytic degradation capabilities for various ECs, effectively and rapidly removing bisphenol A (BPA), ciprofloxacin (CIP), tetracycline (TC), diphenhydramine (DP), 2,4-dichlorophenoxyacetic acid (2,4-D), and phenytoin (PHT) from water. At 5 minutes, the removal rates of BPA and PHT both exceeded 90%. It also demonstrates excellent treatment effects on actual wastewater, achieving a COD removal rate of approximately 90% after 30 minutes of treatment. Furthermore, the catalyst exhibits extremely high salt tolerance; the catalytic effect gradually increases with increasing salt concentration, while simultaneously reducing the amount of H2O2 required and improving its utilization rate.

[0020] (2) The catalyst preparation method of the present invention is simple and requires low equipment. It uses biomass silkworm excrement as raw material to realize the effective utilization of waste resources. At the same time, the catalyst is a heterogeneous solid catalyst, which is convenient for separation and recycling after catalytic reaction and has good continuous cyclic catalytic reaction activity.

[0021] (3) The catalyst described in this invention can carry out catalytic degradation under neutral conditions without adjusting the pH of the catalytic reaction system. Attached Figure Description

[0022] The present invention will be further described with reference to the accompanying drawings, but the embodiments in the drawings do not constitute any limitation on the present invention. For those skilled in the art, other drawings can be obtained based on the following drawings without creative effort.

[0023] Figure 1 This is an SEM image of the catalyst prepared in Example 1;

[0024] Figure 2 This is the XRD pattern of the catalyst prepared in Example 1;

[0025] Figure 3 The degradation effect and degradation time dependence curve of the catalyst prepared in Example 1 on the catalytic degradation of various organic pollutants;

[0026] Figure 4 The catalyst prepared in Example 1 is in different Cl...- Degradation efficiency and time-dependent curves of BPA degradation at different concentrations;

[0027] Figure 5 The degradation effect and degradation time dependence curves of the catalyst prepared in Example 1 on BPA degradation under different hydrogen peroxide concentrations are shown.

[0028] Figure 6 This is a graph showing the recyclability evaluation of the catalyst prepared in Example 1 for BPA degradation.

[0029] Figure 7 The figure shows the degradation rate curve of the ultra-high salinity pharmaceutical wastewater by the catalyst prepared in Example 1. Detailed Implementation

[0030] The present invention will be further described in conjunction with the following embodiments.

[0031] Example 1

[0032] A method for preparing a catalyst for ultra-fast purification of high-salt wastewater assisted by trace amounts of H2O2 includes the following steps:

[0033] (1) Disperse 2g of biomass silkworm excrement in 50mL of deionized water, stir for 15min, add 2mM copper chloride dihydrate, stir for 30min to dissolve it to obtain suspension A;

[0034] (2) Add 1g of tannic acid to the suspension A and stir for 30min to obtain suspension B;

[0035] (3) Add 8g of urea to the suspension B, stir and dissolve thoroughly, then place it in a water bath to evaporate to dryness, and dry it in a forced-air drying oven at 60℃ for 12h. After drying, grind it evenly to obtain the intermediate product.

[0036] (4) The intermediate product was placed in a quartz jar and transferred to a tube furnace. It was then calcined under flowing nitrogen at a temperature of 900°C, a heating rate of 5°C / min, and a holding time of 2 hours. After calcination, it was ground again to obtain Cu-NG@Cu. 0 Fenton catalyst, in the form of a black solid powder.

[0037] The catalyst prepared in Example 1 was characterized, and its SEM image is shown below. Figure 1 ,from Figure 1 It can be seen from Cu-NG@Cu 0 It has a porous structure with a pore size of 0.13 μm, and both copper nanoparticles and urea-derived graphitized layers are confined within the pores.

[0038] The XRD pattern of the catalyst is shown in [reference needed]. Figure 2 Comparison with standard cards revealed that it was similar to Cu 0 Characteristic diffraction peaks (111), (200), (220), characteristic diffraction peaks of Cu2O and characteristic diffraction peaks of carbon 002 crystal plane.

[0039] Table 1 Cu-NG@Cu 0 Numerical fitting results of Cu-order EXAFS oscillations

[0040]

[0041] Table 1 shows Cu-NG@Cu 0 Numerical fitting results of Cu-order EXAFS oscillations. Clearly, the average coordination number of the central Cu atom is 4, with 1.2 O and 1.6 N atoms directly bonded in the first coordination layer, and an average of 0.6 C atoms directly bonded in the second coordination layer. Therefore, in Cu-NG@Cu... 0 On the surface, single-atom Cu interacts strongly with the delocalized π orbitals perpendicular to the aromatic ring plane in the graphene-like NG support through Cu-OC and Cu-NC bond bridges.

[0042] Example 2

[0043] A method for degrading organic pollutants in water includes the following steps:

[0044] 0.01g of Cu-NG@Cu prepared in Example 1 was used. 0 The catalyst was added to 50 mL of a simulated solution with an organic pollutant concentration of 20 μM, and 50 μL of hydrogen peroxide solution (10 mM) was added simultaneously. The mixture was continuously stirred and degraded in a water bath at 35 °C. The pollutant concentration was measured at different time points.

[0045] The organic pollutants are: bisphenol A (BPA), ciprofloxacin (CIP), tetracycline (TC), diphenhydramine (DP), 2,4-dichlorophenoxyacetic acid (2,4-D), and phenytoin (PHT).

[0046] Cu-NG@Cu prepared in Example 1 0 The degradation efficiency and time-dependent curves of the catalyst in the catalytic degradation of various organic pollutants are shown in the figure. Figure 3 ,from Figure 3 As can be seen from this, within 60 minutes, Cu-NG@Cu 0 The H2O2 (10 mM H2O2 concentration) system achieved degradation efficiencies of 100%, 47.3%, 93.6%, 95.8%, 68.7%, and 98.1% for 20 μM BPA, CIP, TC, DP, 2,4-D, and PHT, respectively.

[0047] Example 3

[0048] A method for degrading organic pollutants in water includes the following steps:

[0049] 0.01g of Cu-NG@Cu prepared in Example 1 was used. 0 The catalyst was added to 50 mL of a BPA solution with a BPA concentration of 40 μM and Cl. - BPA was degraded by adding 50 μL of hydrogen peroxide solution to samples at concentrations of 0, 1, 10, and 100 mM, and the samples were continuously stirred in a water bath at 35 °C. The concentration of BPA was measured at different time points.

[0050] Example 4

[0051] A method for degrading organic pollutants in water includes the following steps:

[0052] 0.01g of Cu-NG@Cu prepared in Example 1 was used. 0 The catalyst was added to 50 mL of a BPA solution with a BPA concentration of 40 μM and Cl. - The concentration was 100 mM, and hydrogen peroxide solutions with final concentrations of 0, 0.2, 0.5, 0.8, and 2 mM were added respectively. The mixture was continuously stirred and degraded under a water bath at 35°C, and the BPA concentration was measured at different time points.

[0053] Cu-NG@Cu prepared in Example 1 0 Catalysts in different Cl - The degradation efficiency and time-dependent curves for BPA degradation at different concentrations and under different hydrogen peroxide concentrations are shown in the following figures. Figure 4 , Figure 5 Under otherwise identical conditions, when the initial BPA concentration is 40 μM, the degradation rate of BPA increases with the concentration of Cl. - The concentration increases with increasing concentration, at 100 mM Cl - When present, Cu-NG@Cu 0 BPA can be completely removed within 5 minutes. Figure 4 ), compared to without Cl - Under the same conditions, it is 52.8 times faster, and at the same time, the utilization rate of H2O2 is increased by 5 times. Figure 5 ).

[0054] Example 5

[0055] A method for degrading organic pollutants in water includes the following steps:

[0056] 0.01g of Cu-NG@Cu prepared in Example 1 was used. 0 The catalyst was added to 50 mL of BPA solution, the concentration of organic pollutants in the BPA solution being 20 μM, along with 50 μL of hydrogen peroxide solution. The mixture was continuously stirred and degraded in a 35°C water bath. After 60 min of stirring, a sample was taken to determine the BPA concentration. The Cu-NG@Cu catalyst in the reaction system was then added to the solution. 0 After the catalyst is separated and dried, the dried catalyst is repeatedly subjected to the BPA solution degradation reaction, and its continuous cycle degradation performance is measured.

[0057] Cu-NG@Cu prepared in Example 1 0 See the activity evaluation diagram for the repeated recycling of the catalyst for BPA degradation. Figure 6 ;from Figure 6 It can be observed that the effect of the catalyst in degrading BPA did not decrease significantly after continuous cyclic reaction. In 6 repeated experiments, the removal effect reached more than 95%.

[0058] Example 6

[0059] A method for degrading organic pollutants in water includes the following steps:

[0060] 0.01g of Cu-NG@Cu prepared in Example 1 was used. 0 The catalyst was added to 50 mL of actual ultra-high salinity pharmaceutical wastewater with a salt concentration of 1% and 3.5% by mass. At the same time, 50 μL of hydrogen peroxide solution was added to each wastewater. The wastewater was continuously stirred and degraded under a 35°C water bath. COD or TOC was measured at different time points.

[0061] The Cu-NG@Cu 0 The degradation rate curve of the catalyst on the ultra-high salinity pharmaceutical wastewater is as follows: Figure 7 As shown, within 60 minutes, with the assistance of 1.2 mM H2O2, the COD of pharmaceutical wastewater with a salt content of 1% by mass was reduced from 426.2 mg / L to 93.3 mg / L, achieving a removal rate of 78.1%; while Cu-NG@Cu 0 For pharmaceutical wastewater with a salt content of 3.5% by mass, the TOC could be removed from 178.6 mg / L to 50.2 mg / L within the same time frame using only 2 mM H2O2. These results demonstrate that Cu-NG@Cu 0 It has good application prospects for treating saline / high saline wastewater. Its catalytic degradation process does not depend on H2O2, which is different from the general Fenton reaction process.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a catalyst for ultra-fast purification of high-salt wastewater assisted by trace amounts of H2O2, characterized in that, Includes the following steps: (1) Disperse the biomass silkworm excrement in deionized water, add soluble copper salt, and stir thoroughly to dissolve to obtain suspension A; (2) Add tannic acid to the suspension A, stir thoroughly to dissolve, and then obtain suspension B; (3) Add urea to the suspension B, stir thoroughly to dissolve, evaporate the solvent, dry and grind to obtain the intermediate product; (4) The intermediate product is calcined in flowing nitrogen gas and then ground again to obtain the product; the calcination temperature is 500-900℃, the heating rate is 3-7℃ / min, and the holding time is 2-5h.

2. The preparation method of a trace H2O2-assisted ultra-fast high-salt wastewater purification catalyst according to claim 1, characterized in that, The molar ratio of the biomass silkworm excrement to the soluble copper salt is 0.3-25 g / mM.

3. The preparation method of a trace H2O2-assisted ultra-fast high-salt wastewater purification catalyst according to claim 1, characterized in that, The mass ratio of the biomass silkworm excrement to the tannic acid is 0.5-10 g / g.

4. The preparation method of a trace H2O2-assisted ultra-fast high-salt wastewater purification catalyst according to claim 1, characterized in that, The mass ratio of the biomass silkworm excrement to the urea is 0.06-5 g / g.

5. The preparation method of a trace H2O2-assisted ultra-fast high-salt wastewater purification catalyst according to claim 1, characterized in that, The drying temperature in step (3) is 40-80℃, and the drying time is 8-18h.

6. A trace H2O2-assisted ultra-fast high-salt wastewater purification catalyst, characterized in that, It is prepared by the preparation method according to any one of claims 1-5.

7. The application of the trace H2O2-assisted ultra-fast high-salt wastewater purification catalyst according to claim 6 as a Fenton catalyst in the degradation of organic pollutants in water.

8. The application according to claim 7, characterized in that, The organic pollutants include one or more of bisphenol A, ciprofloxacin, tetracycline, diphenhydramine, 2,4-dichlorophenoxyacetic acid, and phenytoin.

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