Preparation method and application of ultrafast high-salinity wastewater purification catalyst assisted by trace H2O2

Abstract

The invention discloses a preparation method of a trace H2O2-assisted ultrafast high-salinity wastewater purification catalyst, and belongs to the technical field of wastewater degradation catalyst preparation, and the preparation method comprises the following steps: dispersing biomass silkworm excrement in deionized water, adding soluble copper salt, and fully stirring and dissolving to obtain a suspension A; adding tannic acid into the turbid liquid A, and fully stirring and dissolving to obtain turbid liquid B; adding urea into the turbid liquid B, fully stirring and dissolving, evaporating to remove a solvent, drying, and grinding to obtain an intermediate product; and calcining the intermediate product in flowing nitrogen, and grinding again to obtain the product, according to the method disclosed by the invention, the catalyst with excellent catalytic degradation performance on organic pollutants in water is prepared through two-step synthesis of an organic complex reaction and a calcination method, and the catalyst shows efficient catalytic degradation capability and extremely high salt tolerance.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of wastewater degradation catalysts, and particularly relates to a preparation method and application of a catalyst for assisting the ultra-rapid purification of high-salt wastewater with trace H2O2. Background Art

[0002] In aquatic systems, the pollution of emerging contaminants (ECs) is becoming increasingly serious. For example, pharmaceutical active compounds such as antibiotics and endocrine-disrupting chemicals such as bisphenol A can easily cause similar or even more serious problems to aquatic organisms and human health. Especially for highly alkaline wastewater (≥3.5%) generated in various industries such as chemical manufacturing and drinking water desalination, due to the rapid reaction between high-concentration salt ions and free radicals, traditional advanced oxidation processes have also lost their effectiveness and are often accompanied by a large amount of energy consumption. It has been found that heterogeneous catalysts containing cation-π interactions can exhibit efficient degradation of ECs with low oxidant consumption by enhancing interfacial electron directional transfer, which is attributed to strong cationic electrostatic forces. The strength of the cation-π interaction depends on the type of cation and the nature of the π system, indicating that the involved neighboring environment can regulate the strength of the electrostatic field. It is worth noting that the interaction between cations / anions and the π system affects the strength of the cation-π interaction. Therefore, the coordination of these substances with cations and the system in the heterogeneous catalyst can produce different catalytic efficiencies by regulating the strength of the cation-π electrostatic force. Therefore, developing a heterogeneous catalyst containing a cation-π system and using the synergistic coordination of multi-component substances on the catalyst surface to induce charge rearrangement to generate greater electric field energy for ECs cleavage may be a breakthrough for achieving low-energy-consuming and highly efficient high-salt wastewater purification. Summary of the Invention

[0003] In view of the above problems, the present invention provides a preparation method and application of a catalyst for assisting the ultra-rapid purification of high-salt wastewater with trace H2O2.

[0004] The object of the present invention is achieved by the following technical solutions:

[0005] The first aspect of the present invention is to provide a preparation method of a catalyst for assisting the ultra-rapid purification of high-salt wastewater with trace H2O2, comprising the following steps:

[0006] (1) Dispersing biomass silkworm excrement in deionized water, adding a soluble copper salt, and fully stirring and dissolving to obtain a suspension A;

[0007] (2) Adding tannic acid to the suspension A, and fully stirring and dissolving to obtain a suspension B;

[0008] (3) Adding urea to the suspension B, fully stirring and dissolving, then evaporating the solvent, drying, and grinding to obtain an intermediate product;

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

[0010] In some preferred embodiments, the mass 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 temperature of the drying in step (3) is 40 - 80 °C, and the drying time is 8 - 18 h.

[0014] In some preferred embodiments, the temperature of the calcination is 500 - 900 °C, the heating rate is 3 - 7 °C / min, and the heat preservation time is 2 - 5 h.

[0015] The second aspect of the present invention is to provide a catalyst for micro - amount H₂O₂ - assisted ultra - rapid purification of high - salt wastewater, and the catalyst is prepared by the aforementioned preparation method.

[0016] The third aspect of the present invention is to provide an application of a catalyst for micro - amount H₂O₂ - assisted ultra - rapid purification of high - salt wastewater as a Fenton catalyst in the degradation of organic pollutants in water, and the catalyst and hydrogen peroxide are uniformly dispersed in water containing organic pollutants.

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

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

[0019] (1) The method of the present invention is a two-step synthesis method. First, through a simple organic complexation reaction, and then by using the calcination method, a catalyst with excellent catalytic degradation performance for organic pollutants in water is prepared. The structural composition of the catalyst is mainly that copper and graphene-like structures are bonded through Cu-N-C and Cu-O-C bonds and coated with zero-valent copper, forming cation-π electrostatic force on the surface of the catalyst. During the catalytic degradation reaction process, the synergistic coordination of ECs, H2O, and salts on the surface of the catalyst can induce the rearrangement of the surface charge of the catalyst, strengthen the chemical adsorption of ECs and H2O, and generate a stronger surface electric field energy. Only under the condition of low oxidant consumption, the catalyst shows high catalytic degradation ability for various ECs, and can effectively and rapidly remove bisphenol A (BPA), ciprofloxacin (CIP), tetracycline (TC), diphenhydramine (DP), 2,4-dichlorophenoxyacetic acid (2,4-D), and phenytoin (PHT) in water. At 5 minutes, the removal rates of BPA and PHT both exceed 90%. It also has a good treatment effect on actual wastewater. After 30 minutes of treatment, the COD removal rate reaches about 90%. Moreover, the catalyst also shows extremely high salt tolerance. With the increase of the salt concentration, the catalytic effect gradually enhances, and at the same time, it can reduce the dosage of H2O2 and improve the utilization rate.

[0020] (2) The preparation method of the catalyst of the present invention is simple, with low equipment requirements. Using biomass silkworm excrement as the raw material, it realizes 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 the catalytic reaction, and has good continuous cyclic catalytic reaction activity.

[0021] (3) The catalyst of the present invention can carry out catalytic degradation under neutral conditions without the need to adjust the pH of the catalytic reaction system. Description of the Drawings

[0022] The present invention is further described with reference to the accompanying drawings. However, the embodiments in the drawings do not constitute any limitation to the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the following drawings.

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

[0024] Figure 2 It is the XRD spectrum of the catalyst prepared in Example 1;

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

[0026] Figure 4 It is the catalyst prepared in Example 1 under different Cl- Degradation effect and degradation time-dependent curve during catalytic degradation of BPA at [concentration];

[0027] Figure 5 It is the degradation effect and degradation time-dependent curve during catalytic degradation of BPA by the catalyst prepared in Example 1 at different hydrogen peroxide concentrations;

[0028] Figure 6 It is the evaluation diagram of the cyclic reuse activity of the catalyst prepared in Example 1 for BPA degradation;

[0029] Figure 7 It is the degradation rate curve of the ultra-high salinity pharmaceutical wastewater by the catalyst prepared in Example 1. Detailed implementation mode

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

[0031] Example 1

[0032] A preparation method of a trace H2O2-assisted ultra-fast high-salinity wastewater purification catalyst, comprising the following steps:

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

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

[0035] (3) Add 8 g of urea to the suspension B, stir and dissolve it fully, then place it in a water bath to evaporate to dryness, put it into a blast drying oven for drying, the drying temperature is 60 °C, the drying time is 12 h, and after drying, grind it evenly to obtain an intermediate product;

[0036] (4) Place the intermediate product in a quartz crucible, transfer it to a tubular furnace, and calcine it under flowing nitrogen, the calcination temperature is 900 °C, the heating rate is 5 °C / min, the holding time is 2 h, and after calcination, grind it again to prepare Cu-NG@Cu 0 Fenton catalyst, in the form of black solid powder.

[0037] Characterize the catalyst prepared in Example 1, and the SEM diagram of the catalyst is shown in Figure 1 From Figure 1 it can be seen that Cu-NG@Cu 0 has a porous structure, its pore size is 0.13 μm, and both copper nanoparticles and urea-derived graphitized layers are confined in the pores.

[0038] The XRD spectrum of the catalyst is shown inFigure 2 , comparison with the standard card revealed that it was the same as Cu 0 's characteristic diffraction peaks (111), (200), (220), the characteristic diffraction peaks of Cu2O, and the characteristic diffraction peak of the 002 crystal plane of carbon.

[0039] Table 1 Cu-NG@Cu 0 's fitting results of Cu-order EXAFS oscillation values

[0040]

[0041] Table 1 shows the fitting results of Cu-order EXAFS oscillation values of Cu-NG@Cu 0 . Obviously, the average coordination number of the central Cu atom is 4. There are 1.2 O and 1.6 N atoms directly connected in the first coordination layer, and on average 0.6 C atoms directly connected in the second coordination layer. Therefore, on the surface of Cu-NG@Cu 0 , single-atom Cu has a strong Cu-π interaction with the delocalized π orbitals perpendicular to the aromatic ring plane in the graphene-like NG support through Cu-O-C and Cu-N-C bond bridges.

[0042] Example 2

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

[0044] Adding 0.01 g of the Cu-NG@Cu 0 catalyst prepared in Example 1 to 50 mL of a simulated solution, wherein the concentration of the organic pollutant in the simulated solution is 20 μM, and at the same time adding 50 μL of a hydrogen peroxide solution (10 mM), and performing continuous stirring degradation under the condition of a 35 °C water bath, and sampling at different time points to measure the pollutant concentration;

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

[0046] The degradation effect and degradation time dependence curve of the Cu-NG@Cu 0 catalyst prepared in Example 1 during the catalytic degradation of each organic pollutant are shown in Figure 3 , and it can be seen from Figure 3 that within 60 min, the degradation efficiencies of the Cu-NG@Cu 0 / H2O2 (H2O2 concentration is 10 mM) system for 20 μM BPA, CIP, TC, DP, 2,4-D, and PHT can reach 100%, 47.3%, 93.6%, 95.8%, 68.7%, and 98.1% respectively.

[0047] Example 3

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

[0049] Add 0.01 g of the Cu-NG@Cu catalyst prepared in Example 1 0 to 50 mL of a BPA solution with a BPA concentration of 40 μM and Cl - concentrations of 0, 1, 10, and 100 mM, respectively. At the same time, add 50 μL of hydrogen peroxide solution and continuously stir for degradation under a water bath condition at 35°C. Sample at different time points to measure the BPA concentration.

[0050] Example 4

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

[0052] Add 0.01 g of the Cu-NG@Cu catalyst prepared in Example 1 0 to 50 mL of a BPA solution with a BPA concentration of 40 μM and Cl - concentration of 100 mM. At the same time, add hydrogen peroxide solutions with final concentrations of 0, 0.2, 0.5, 0.8, and 2 mM, respectively, and continuously stir for degradation under a water bath condition at 35°C. Sample at different time points to measure the BPA concentration.

[0053] The Cu-NG@Cu catalyst prepared in Example 1 0 catalyst's degradation effect and degradation time dependence curve when catalyzing the degradation of BPA at different Cl - concentrations and different hydrogen peroxide concentrations are respectively shown in Figure 4 , Figure 5 . Under the condition that other conditions are the same, when the initial BPA concentration is 40 μM, the degradation rate of BPA increases with the increase of Cl - concentration. In the presence of 100 mM Cl - , Cu-NG@Cu 0 can completely remove BPA within 5 minutes( Figure 4 ), which is 52.8 times faster than under the condition without Cl - . 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, comprising the following steps:

[0056] Add 0.01 g of the Cu-NG@Cu catalyst prepared in Example 1 0 to 50 mL of the BPA solution with an organic pollutant concentration of 20 μM in the BPA solution. At the same time, add 50 μL of hydrogen peroxide solution and carry out continuous stirring degradation under the condition of a 35 °C water bath. After stirring and reacting for 60 min, take a sample to measure the BPA concentration; Separate and dry the Cu-NG@Cu 0 catalyst in the reaction system. After drying, take the dried catalyst and repeat the BPA solution degradation reaction to measure its continuous cyclic degradation performance.

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

[0058] Example 6

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

[0060] Add 0.01 g of the Cu-NG@Cu catalyst prepared in Example 1 0 to 50 mL of actual ultra-high salt pharmaceutical wastewater with a salt mass concentration of 1% and 3.5% in the ultra-high salt pharmaceutical wastewater. At the same time, add 50 μL of hydrogen peroxide solution respectively and carry out continuous stirring degradation under the condition of a 35 °C water bath. Take samples at different time points to measure COD or TOC.

[0061] The Cu-NG@Cu 0 The degradation rate curve of the catalyst for the ultra-high salt pharmaceutical wastewater is as shown in Figure 7 . Within 60 min, with the assistance of 1.2 mM H2O2, the COD of the pharmaceutical wastewater with a salt mass ratio of 1% decreased from 426.2 mg / L to 93.3 mg / L, and the removal rate reached 78.1%; while for the pharmaceutical wastewater with a salt mass ratio of 3.5%, the Cu-NG@Cu 0 could also reduce its TOC from 178.6 mg / L to 50.2 mg / L within the same time only with the assistance of 2 mM H2O2; The above results indicate that Cu-NG@Cu 0 has good application prospects for treating saline / high-salt wastewater, and 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, rather than limiting the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a trace H2O2-assisted ultra-fast high-salinity wastewater purification catalyst, characterized in that: The following steps are involved: (1) Dispersing biomass silkworm litter in deionized water, adding soluble copper salt, and stirring to dissolve to obtain suspension A; (2) adding tannic acid to the suspension A, stirring and dissolving the mixture to obtain a suspension B; (3) adding urea to the suspension B, stirring thoroughly to dissolve, evaporating the solvent, drying, and grinding to obtain an intermediate product; (4) The intermediate product is calcined in flowing nitrogen and then ground again to obtain the product.

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

3. The method for preparing 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 litter to the tannic acid is 0.5-10 g / g.

4. The method for preparing 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 litter to the urea is 0.06-5g / g.

5. The method for preparing 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° C. and the drying time is 8-18 hours.

6. The method for preparing a trace H2O2-assisted ultra-fast high-salinity wastewater purification catalyst according to claim 1, characterized in that: The calcination temperature is 500-900°C, the heating rate is 3-7°C / min, and the heat preservation time is 2-5h.

7. A trace amount of H2O2 assisted ultra-fast high-salinity wastewater purification catalyst, characterized in that: Prepared according to the preparation method according to any one of claims 1 to 7.

8. Use of a trace H2O2-assisted ultra-fast high-salt wastewater purification catalyst as claimed in claim 7 as a Fenton catalyst in the degradation of organic pollutants in water.

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

Images