A method for efficiently catalyzing peracetic acid to treat pollutants with an iron boride-based material

Abstract

The present invention belongs to the field of wastewater treatment, and provides a method for efficiently catalyzing peracetic acid with an iron boride-based material to treat pollutants, and the operation is as follows: micron-sized zero-valent iron boride and peracetic acid are added to the wastewater containing organic pollutants, and the wastewater is treated under stirring conditions; during the wastewater treatment process, the micron-sized zero-valent iron boride catalytically activates peracetic acid to generate hydroxyl radicals, organic radicals CH<subgt;3< / subgt;C(O)O· and CH<subgt;3< / subgt> C(O)OO· to degrade the organic pollutants in the wastewater; after the treatment of a batch of wastewater is completed, the micron-sized zero-valent iron boride is recovered for the treatment of the next batch of wastewater; the micron-sized zero-valent iron boride is obtained by fully ball-milling a boron precursor and micron-sized zero-valent iron, and the boron precursor is at least one of boron oxide and boric acid. The present invention enriches the types of iron-based materials that can efficiently catalytically activate PAA to generate ROS to degrade pollutants, can improve the recyclability of iron-based materials and reduce the wastewater treatment cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of wastewater treatment, and relates to a method for efficiently catalyzing peracetic acid by a boronized iron-based material to treat pollutants. Background Art

[0002] Peracetic acid (PAA) has been applied to wastewater disinfection in the United States, Canada, and Europe due to its strong bactericidal ability and limited formation of toxic by-products. However, due to its high selectivity, PAA cannot directly degrade micropollutants, and introducing external energy or / and catalysts has the potential to enhance the oxidation ability of PAA and promote the generation of a large number of reactive oxygen species (ROS). In previous studies, there have been reports of using heterogeneous catalysts to activate PAA. However, these heterogeneous catalytic systems generally have problems of slow degradation rate and metal leaching, which can cause consequences such as toxicity and carcinogenicity, not only threatening human health, but also having poor stability of the heterogeneous catalyst and difficulty in material recycling. Therefore, it is very necessary to develop efficient, environmentally friendly, economical, and stable catalysts for activating PAA to degrade pollutants.

[0003] Iron-based materials, especially zero-valent iron (ZVI), are commonly used in fields such as heavy metal adsorption, reduction of refractory pollutants, and activation of O2, H2O2, persulfate (PDS), and peroxymonosulfate (PMS) for degradation of micropollutants. CN112723518A discloses a method for degrading antibiotics in water by activating peracetic acid with zero-valent metal. By adding PAA to a water body to be treated containing tetracycline so that its concentration is 70-100 μM, and adding nano-zero-valent iron so that its concentration is 0.08-0.1 g / L, and adjusting the pH value to 3.5-4.5, the nano-zero-valent iron activates PAA to generate free radicals to degrade tetracycline in the water body. However, in this method, the oxidation passivation layer generated during the production and use of zero-valent iron easily leads to its low reactivity, which will not only reduce the degradation efficiency of pollutants, but also reduce the recyclability of zero-valent iron. Therefore, in order to improve the efficiency of degrading pollutants based on PAA and improve the recyclability of zero-valent iron, it is necessary to seek catalytic materials with better performance to catalyze the degradation of pollutants in wastewater by PAA.

[0004] However, studies have found that most of the iron-based materials in the prior art that can catalyze H2O2, PDS and PMS to produce ROS to degrade pollutants cannot catalyze PAA to produce ROS, indicating that iron-based materials have a high specificity for the catalysis of PAA. At present, the types of iron-based materials that can catalyze PAA to produce ROS reported in the literature are also very limited. For example, there are reports of using CoFe2O4 to catalyze the degradation of sulfamethoxazole by PAA, but the pH range of application of this method is limited, and the degradation efficiency of pollutants is also poor; for another example, using the same iron-cobalt material, there are reports of using zero-valent iron-cobalt bimetallic materials to synergistically activate PAA to treat wastewater, but the recycling performance of this material needs to be improved. Based on the above-mentioned technical status, the present invention hopes to use iron-based materials different from the prior art to catalyze PAA to degrade pollutants in wastewater. On the one hand, it enriches the types of iron-based materials that can catalyze PAA to produce ROS to degrade pollutants. On the other hand, it improves the recycling performance of iron-based catalytic materials that catalyze PAA and improves the wastewater degradation efficiency. Summary of the Invention

[0005] In response to the problems in the prior art that the types of iron-based materials that can catalyze PAA to produce ROS are limited and the recycling performance of iron-based materials catalyzing PAA needs to be improved, the present invention provides a method for using boride-based materials to efficiently catalyze peracetic acid to treat pollutants, thereby enriching the types of iron-based materials that can efficiently catalyze the activation of PAA to produce ROS to degrade pollutants, improving the degradation efficiency of wastewater, improving the recycling performance of iron-based materials, and reducing wastewater treatment costs.

[0006] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is as follows:

[0007] A method for treating pollutants using iron boride-based materials to efficiently catalyze peracetic acid comprises the following steps:

[0008] Adding micron-sized zero-valent iron boride and peracetic acid to wastewater containing organic pollutants, treating the wastewater under stirring conditions, controlling the concentration of the micron-sized zero-valent iron boride in the wastewater to 50-150 mg / L and the concentration of the peracetic acid in the wastewater to 0.1-0.4 mmol / L; during the wastewater treatment process, the micron-sized zero-valent iron boride catalytically activates the peracetic acid to produce hydroxyl radicals and organic free radicals CH3C(O)O· and CH3C(O)OO·, which degrade the organic pollutants in the wastewater; after completing the treatment of one batch of wastewater, recycling the micron-sized zero-valent iron boride for use in treating the next batch of wastewater;

[0009] The micron-sized zero-valent iron boride is prepared by mixing a boron precursor with micron-sized zero-valent iron and then fully ball-milling the mixture. The iron species in the micron-sized zero-valent iron boride include Fe(II), Fe(III) and Fe 0, the boron species include boron oxides and FeB, and the boron precursor is at least one of boron oxide (B2O3) and boric acid (H3BO3).

[0010] In the above technical solution, the preferred preparation method of micron-sized boronized zero-valent iron is: mixing the boron precursor and micron-sized zero-valent iron according to a molar ratio of boron to iron of (0.01 - 0.08):1, and then ball-milling for at least 4 h to obtain it.

[0011] Furthermore, in the above technical solution, the more preferred preparation method of micron-sized boronized zero-valent iron is: mixing the boron precursor and micron-sized zero-valent iron according to a molar ratio of boron to iron of (0.01 - 0.05):1, and then ball-milling for at least 4 h to obtain it.

[0012] In the above technical solution, the particle size of the micron-sized boronized zero-valent iron is preferably 100 - 500 μm.

[0013] In the above technical solution, it is preferably ball-milled at a rotation speed of 400 - 800 rpm for 4 - 6 h to obtain micron-sized boronized zero-valent iron. In the above technical solution, the micron-sized boronized zero-valent iron has excellent recyclability. Especially when boron oxide (B2O3) is used as the boron precursor, the prepared micron-sized boronized zero-valent iron has relatively more excellent recyclability. For example, the present invention has confirmed through experiments that when the micron-sized boronized zero-valent iron prepared with boron oxide (B2O3) as the boron precursor is used to catalytically activate peracetic acid to degrade sulfamethoxazole (SMX) wastewater, after 7 cycles, the removal rate of SMX hardly changes; when the micron-sized boronized zero-valent iron prepared with boric acid (H3BO3) as the boron precursor is used to catalytically activate peracetic acid to degrade SMX wastewater, after 6 cycles, the removal rate of SMX can still remain above 90%, and after 7 cycles, the removal rate of SMX still remains above 80%.

[0014] In the above technical solution, the preferably controlled number of recycling times is at least 7 times. Furthermore, according to the types and concentrations of pollutants in the wastewater containing organic pollutants in actual applications, the number of recycling times of the micron-sized boronized zero-valent iron can be controlled to be 7 - 12 times.

[0015] In the above technical solution, the pH value of the wastewater containing organic pollutants is between 3 and 9.

[0016] In the above technical solution, the wastewater treatment time is determined according to the water quality of the wastewater containing organic pollutants (such as the types and concentrations of organic pollutants and the pH value of the wastewater, etc.). Usually, it is sufficient to treat until the removal rate of pollutants in the wastewater reaches equilibrium. Generally speaking, the wastewater treatment time does not exceed 1 h. For example, the wastewater treatment time is usually 10 - 30 min.

[0017] The present invention has been experimentally verified that the above technical solution can effectively resist the influence of the water matrix on the degradation of pollutants. For example, it can overcome the adverse effects caused by common anions such as low-concentration Clˉ, NO3ˉ, and H2PO4ˉ in wastewater on the degradation process. Therefore, in the above technical solution, the wastewater containing organic pollutants may further contain at least one of Clˉ, NO3ˉ, and H2PO4ˉ.

[0018] Taking the degradation experiment of sulfamethoxazole as an example, the present invention has verified that in the above technical solution, the hydroxyl radicals generated by the catalytic activation of peracetic acid by micron-sized boronized zero-valent iron contribute the most to the degradation of organic pollutants in wastewater, and the organic radicals CH3C(O)O· and CH3C(O)OO· contribute less to the degradation of organic pollutants in wastewater. The two effects work together to achieve the technical effects of effectively improving the degradation efficiency and the degradation effect.

[0019] In the above technical solution, it is preferably to control the stirring conditions during the wastewater treatment process to make the micron-sized boronized zero-valent iron in a fluidized state.

[0020] Compared with the prior art, the technical solution provided by the present invention has the following beneficial technical effects:

[0021] 1. The present invention provides a method for efficiently catalyzing peracetic acid by a boronized iron-based material to treat polluted wastewater. This method efficiently catalyzes and activates peracetic acid by micron-sized boronized zero-valent iron to generate hydroxyl radicals, organic radicals CH3C(O)O· and CH3C(O)OO·, and uses these radicals to degrade the pollutants in the wastewater. Compared with the case of directly catalyzing and activating peracetic acid by zero-valent iron to treat wastewater, the present invention can effectively improve the degradation efficiency of polluted wastewater and improve the treatment effect on polluted wastewater; compared with the case of using other iron-based catalytic materials to catalyze and activate peracetic acid to treat wastewater in the prior art, the recycling performance of micron-sized boronized zero-valent iron in the method of the present invention has been improved, which is beneficial to reducing the treatment cost of polluted wastewater.

[0022] 2. The present invention has been experimentally verified that the method of the present invention can achieve complete removal of SMX in the simulated wastewater of sulfamethoxazole (SMX) in 10-15 minutes, has excellent catalytic activity and stability, and the micron-sized boronized zero-valent iron can be reused multiple times to reduce the operating cost. At the same time, the preparation method of the micron-sized boronized zero-valent iron is simple, without secondary pollution, easy to realize large-scale production, with a small addition amount of boron precursor and low cost. These characteristics are beneficial to the large-scale application of the method of the present invention and show excellent wastewater degradation performance in practical applications.

[0023] 3. The present invention has been experimentally verified that the method of the present invention can also have a good degradation effect under the condition of the existence of the water matrix. For example, it can overcome the common Clˉ, NO3ˉ, and H2PO4 in the water body2 ˉThe adverse effects of anions such as ˉ on the degradation of pollutants. Therefore, in water bodies with a low water matrix concentration, the present invention also has good degradation ability for organic pollutants. At the same time, the method of the present invention can achieve efficient activation of PAA and efficient degradation of pollutants within a relatively wide pH range (3 - 9), which is also beneficial to broadening the application scope of this method and reducing the consumption of chemicals for adjusting the pH value of wastewater during wastewater treatment, thereby reducing the cost of wastewater treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Figure (a) is the SEM image of ZVI before and after treating wastewater. Figure 1 Figure (b) is the SEM image of B-ZVI B2O3 before and after treating wastewater. Figure 1 Figure (c) is the SEM image of B-ZVI H3BO3 before and after treating wastewater. Figure 1 Figure (d) is the SEM image of B-ZVI Na2B4O7 before and after treating wastewater.

[0025] Figure 2 Figure (a) is the XRD pattern of ZVI before and after treating wastewater. Figure 2 Figure (b) is the XRD pattern of B-ZVI B2O3 before and after treating wastewater. Figure 2 Figure (c) is the XRD pattern of B-ZVI H3BO3 before and after treating wastewater. Figure 2 Figure (d) is the XRD pattern of B-ZVI before and after treating the wastewater Na2B4O7 before and after treating wastewater.

[0026] Figure 3 Figure (a) is the XPS pattern of B in B-ZVI before treating wastewater B2O3 before treating wastewater. Figure 3 Figure (b) is the XPS pattern of B in B-ZVI H3BO3 before treating wastewater. Figure 3 Figure (c) is the XPS pattern of B in B-ZVI Na2B4O7 before treating wastewater.

[0027] Figure 4 Figures (A) and (B) are the synchrotron radiation spectra of iron and boron in the micron-sized boronized zero-valent iron prepared in Example 1, respectively.

[0028] Figure 5 is a comparison chart of the degradation performance of pollutants by different catalysts for catalytic activation of PAA.

[0029] Figure 6 Figures (a), (b), and (c) are different catalysts (B-ZVI B2O3 and B-ZVI H3BO3, B-ZVI Na2B4O7 ) Identification diagram of ROS generated by catalytic activation of PAA by Figure 6 Figure (d) shows the contribution degree of different types of free radicals generated by different catalysts activating PAA to the reaction rate constant.

[0030] Figure 7 It is the identification diagram of ROS generated by catalytic activation of PAA with ZVI prepared in Comparative Example 1.

[0031] Figure 8 It is the influence diagram of different anions on the degradation of organic pollutants by different catalytic activation of PAA.

[0032] Figure 9 Figure (a) shows B-ZVI B2O3 Recycling performance diagram of Figure 9 Figure (b) shows B-ZVI H3BO3 Recycling performance diagram of Figure 9 Figure (c) shows B-ZVI Na2B4O7 Recycling performance diagram of

[0033] Figure 10 Comparison diagram of the degradation of SMX by catalytic activation of PAA with micron-scale iron boride zero-valent iron prepared by feeding in different molar ratios.

[0034] Figure 11 It is the test result of the ability of the pH value of the wastewater containing organic pollutants to degrade pollutants by catalyst-activated PAA. Detailed implementation method

[0035] The following further illustrates the method for efficiently treating pollutants by iron boride-based materials provided by the present invention through examples. It is necessary to point out that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the protection scope of the present invention. Those skilled in the art make some non-essential improvements and adjustments to the present invention based on the above-mentioned invention content for specific implementation, and still fall within the protection scope of the present invention.

[0036] In the following examples, the peracetic acid (PAA) used is analytical pure PAA.

[0037] Example 1

[0038] In this example, the preparation of the iron boride-based material - micron-scale iron boride zero-valent iron (B-ZVI) is as follows:

[0039] According to the molar ratio of boron to iron of 0.02:1, micron-scale zero-valent iron and boron oxide are added to the ball milling tank of a planetary ball mill, grinding balls are added, and ball milling is carried out at a speed of 500 rpm for 5 h to obtain iron boride zero-valent iron, denoted as B-ZVI B2O3 .

[0040] According to the molar ratio of boron to iron of 0.02:1, micron-sized zero-valent iron and boric acid were added to the ball milling tank of a planetary ball mill, grinding balls were added, and ball milling was carried out at a speed of 500 rpm for 5 h to obtain boronized zero-valent iron, denoted as B-ZVI H3BO3 。

[0041] According to the molar ratio of boron to iron of 0.02:1, micron-sized zero-valent iron and sodium tetraborate were added to the ball milling tank of a planetary ball mill, grinding balls were added, and ball milling was carried out at a speed of 500 rpm for 5 h to obtain boronized zero-valent iron, denoted as B-ZVI Na2B4O7 。

[0042] Comparative Example 1

[0043] In this comparative example, unloaded micron-sized zero-valent iron was prepared, and the operation was as follows:

[0044] The micron-sized zero-valent iron was added to the ball milling tank of a planetary ball mill, grinding balls were added, and ball milling was carried out at a speed of 500 rpm for 5 h to obtain unloaded micron-sized zero-valent iron, denoted as ZVI.

[0045] Example 2

[0046] In this example, the micron-sized boronized zero-valent iron (B-ZVI) prepared in Example 1 was characterized.

[0047] (1) The micron-sized boronized zero-valent iron prepared in Example 1 and the ZVI prepared in Comparative Example 1 were characterized by scanning electron microscopy (SEM), X-ray diffraction pattern (XRD), and X-ray photoelectron spectroscopy (XPS).

[0048] (2) In order to compare the changes of the micron-sized boronized zero-valent iron (B-ZVI) prepared in Example 1 and the ZVI prepared in Comparative Example 1 before and after use, the B-ZVI prepared in Example 1 and the ZVI prepared in Comparative Example 1 were used to treat wastewater, and the B-ZVI and ZVI in the treated wastewater were taken for the same characterization as in step (1).

[0049] The operations and conditions for treating wastewater are as follows:

[0050] The micron-sized boronized zero-valent iron (B-ZVI B2O3 、B-ZVI H3BO3 or B-ZVI Na2B4O7) and peracetic acid (PAA) were added to an SMX aqueous solution (simulated wastewater, pH about 7) with an SMX concentration of 10 μmol / L. The concentration of micron-sized zero-valent iron boride in the wastewater was controlled at 100 mg / L, and the concentration of PAA in the wastewater was 0.2 mmol / L. The treatment was carried out for 15 min at 25 °C and a rotation speed of 300 r / min.

[0051] As a control, the ZVI and PAA prepared in Comparative Example 1 were added to an SMX aqueous solution with an SMX concentration of 10 μmol / L. The concentrations of ZVI and S-ZVI in the wastewater were controlled at 100 mg / L, and the concentration of PAA in the wastewater was 0.2 mmol / L. The treatment was carried out for 15 min at 25 °C and a rotation speed of 300 r / min.

[0052] Figure 1 Figure (a) is the SEM image of ZVI before and after treating the wastewater. Figure 1 Figure (b) is the SEM image of B-ZVI B2O3 before and after treating the wastewater. Figure 1 Figure (c) is the SEM image of B-ZVI H3BO3 before and after treating the wastewater. Figure 1 Figure (d) is the SEM image of B-ZVI Na2B4O7 before and after treating the wastewater. Figure 2 Figure (a) is the XRD pattern of ZVI before and after treating the wastewater. Figure 2 Figure (b) is the XRD pattern of B-ZVI B2O3 before and after treating the wastewater. Figure 2 Figure (c) is the XRD pattern of B-ZVI H3BO3 before and after treating the wastewater. Figure 2 Figure (d) is the XRD pattern of B-ZVI Na2B4O7 before and after treating the wastewater. Figure 3 Figures (a), (b), and (c) are the XPS spectra of B in B-ZVI B2O3 , B-ZVI H3BO3 , B-ZVI Na2B4O7 before treating the wastewater, respectively. Figure 4 is the synchrotron radiation image of iron and boron in the micron-sized zero-valent iron boride prepared in Example 1.

[0053] From Figure 1 Figures (a), (b), (c), and (d), it can be seen that before and after treating the wastewater, the surface changes of ZVI and micron-sized zero-valent iron boride (B-ZVI B2O3 , B-ZVI H3BO3 , B-ZVI Na2B4O7 ) are not obvious. From Figure 2 it can be seen that in ZVI and micron-sized zero-valent iron boride (B-ZVIB2O3 , B-ZVI H3BO3 , B-ZVI Na2B4O7 ) the diffraction peaks of Fe 0 (2θ = 44.7°, 65.1° and 82.4°) can be clearly found. After treating the wastewater, in the micron-scale zero-valent iron boride (B-ZVI B2O3 , B-ZVI H3BO3 , B-ZVI Na2B4O7 ) the diffraction peaks of Fe 0 weaken more significantly, indicating that part of the iron is oxidized or consumed during the wastewater treatment process. However, for ZVI, before and after the wastewater treatment, the intensity of the Fe 0 diffraction peaks of ZVI is similar, indicating that the corrosion degree and rate of ZVI are not as high as those of the micron-scale zero-valent iron boride (B-ZVI B2O3 , B-ZVI H3BO3 , B-ZVI Na2B4O7 ). From Figure 3 figures (a), (b) and (c), it can be seen that in the micron-scale zero-valent iron boride (B-ZVI B2O3 , B-ZVI H3BO3 , B-ZVI Na2B4O7 ), B mainly exists in the form of boron oxides, which may be related to the fact that the precursors of the micron-scale zero-valent iron boride all contain B-O bonds or the oxidation of B during the preparation and wastewater treatment processes. After ball milling, a certain amount of Fe-B bonds are formed on the surface of the micron-scale zero-valent iron boride, indicating that a chemical reaction occurs between B and zero-valent iron during the ball milling process, rather than simple physical mixing. Combining the XPS results shown in Figure 3 and the synchrotron radiation data shown in Figure 4 , the coordination environment and valence state of iron elements, as well as the composition and valence state of boron elements in the micron-scale zero-valent iron boride can be known.

[0054] Example 3

[0055] In this example, an SMX aqueous solution was used as the simulated wastewater, and the micron-scale zero-valent iron boride (B-ZVI) prepared in Example 1 and the ZVI prepared in Comparative Example 1 were used as catalysts to catalyze PAA for wastewater treatment, and their catalytic performances were compared as follows:

[0056] The catalyst and PAA were added to an SMX aqueous solution (simulated wastewater) with an SMX concentration of 10 μmol / L. The concentration of the catalyst in the wastewater was controlled at 100 mg / L, and the concentration of PAA in the wastewater was 0.2 mmol / L. The treatment was carried out for 15 min at 25 °C and a rotation speed of 300 r / min. During the wastewater treatment process, samples were taken at regular intervals to measure the concentration of SMX in the wastewater, and the ratio C / C0 of the SMX concentration to its initial concentration was calculated. A total of 4 groups of experiments were conducted, and the catalysts used in each group of experiments were B-ZVI prepared in Example 1 B2O3 、B-ZVI H3BO3 、B-ZVI Na2B4O7 and ZVI prepared in Comparative Example 1. The results are as Figure 5 shown

[0057] From Figure 5 the variation of C / C0 with the wastewater treatment time shown, compared with ZVI prepared in Comparative Example 1, B-ZVI B2O3 、B-ZVI H3BO3 and B-ZVI Na2B4O7 prepared in Example 1 have significantly better performance in catalytically activating PAA to degrade SMX. Especially, B-ZVI B2O3 has better catalytic performance, indicating that the micron-scale zero-valent iron boride prepared by combining zero-valent iron and boron precursor in an appropriate ratio and by a specific process in the present invention can effectively improve its ability to catalytically activate PAA

[0058] Example 4

[0059] In this example, the quenching experiment method was used to explore the types of ROS generated when the micron-scale zero-valent iron boride prepared in Example 1 and ZVI prepared in Comparative Example 1 catalytically activated PAA

[0060] The catalyst and PAA were added to an SMX aqueous solution (simulated wastewater) with an SMX concentration of 10 μmol / L. The concentration of the catalyst in the wastewater was controlled at 100 mg / L, and the concentration of PAA in the wastewater was 0.2 mmol / L. The wastewater was treated at 25 °C and a rotation speed of 300 r / min. An excessive amount of quenching agent also needed to be added during the quenching experiment. A total of 3 groups of experiments were conducted, and the catalysts used in each group of experiments were B-ZVI B2O3 、B-ZVI H3BO3 、B-ZVI Na2B4O7 and ZVI prepared in Comparative Example 1

[0061] In the quenching experiment, excessive tert-butanol (TBA, concentration of 100 mmol / L) was used as the hydroxyl radical ·Quenchers of OH, using 2,4 - hexadiene (2,4 - HD, concentration of 10 mmol / L) as the quencher of organic free radical R - O· (in this example, it is CH3C(O)O · and CH3C(O)OO · ), and using methanol (METH, concentration of 100 mmol / L) as the quencher of · OH and R - O·. The case without adding quenchers was used as the control group (Control). When the catalyst used was B - ZVI B2O3 prepared in Example 1, B - ZVI H3BO3 , B - ZVI Na2B4O7 , the results of the quenching experiment are as shown in Figure 6 . When the catalyst used was ZVI prepared in Comparative Example 1, the results of the quenching experiment are as shown in Figure 7 . Figure 6 And Figure 7 The Control group in them was the case without adding quenchers.

[0062] In the quenching experiment, it was determined whether there was a corresponding ROS according to whether the degradation of the corresponding pollution was inhibited after adding the quencher. As can be seen from Figure 6 , there was · OH in all three B - ZVI / PAA systems, and there was a certain amount of R - O·. According to the calculation of the contribution to the reaction rate constant, · the contribution degree of OH to the reaction rate constant during the degradation of SMX was between 60% and 80%, and the contribution degree of R - O· to the reaction rate constant during the degradation of SMX was between 10% and 20%, as shown in the (d) graph of Figure 6 . From the results of the quenching experiment, it can be seen that the B - ZVI / PAA system of the present invention produced ROS including · OH and R - O·.

[0063] As can be seen from Figure 7 , when ZVI catalyzed the activation of PAA to degrade SMX, the removal rate of SMX was only about 60%. At the same time, the types and proportions of free radicals generated by the ZVI / PAA system were almost the same as those of the B - ZVI / PAA system, indicating that the ZVI / PAA system also produced · ROS including OH and R - O·. However, the ability of the B - ZVI / PAA system of the present invention to degrade pollutants was significantly improved, proving that the concentration of free radicals produced by the B - ZVI / PAA system of the present invention was significantly higher than that of the ZVI / PAA system, which was the reason why the method of the present invention had a better pollutant removal effect.

[0064] As shown in Figure 11As shown, the ability of single ZVI to activate and degrade pollutants by PAA is weak (removal rate of about 60%), but with the introduction of boron, the ability of the B-ZVI / PAA system to degrade pollutants is significantly improved, and the types and proportions of free radicals generated in the ZVI / PAA system are almost the same as those in the B-ZVI / PAA system, proving that the concentration of free radicals generated in the B-ZVI / PAA system is higher than that in the single ZVI / PAA system, and thus has a better pollutant removal effect.

[0065] Example 5

[0066] In order to explore the tolerance of the method provided by the present invention to different water matrices in actual wastewater treatment, in this example, an SMX aqueous solution was used as the simulated wastewater, and the effects of common anions Clˉ, NO3ˉ, H2PO4ˉ, and HCO3ˉ in the wastewater on the degradation of pollutants by the S-ZVI / PAA system were investigated under certain concentration conditions.

[0067] Using the micron-scale boronized zero-valent iron (B-ZVI B2O3 、B-ZVI H3BO3 or B-ZVI Na2B4O7 ) prepared in Example 1 as the catalyst, the catalyst and PAA were added to an SMX aqueous solution (simulated wastewater) with an SMX concentration of 10 μmol / L, the concentration of the catalyst in the wastewater was controlled to be 100 mg / L, and the concentration of PAA in the wastewater was 0.2 mmol / L. It was treated for 15 min at 25 °C and a rotation speed of 300 r / min. During the wastewater treatment process, samples were taken at regular intervals to measure the concentration of SMX in the wastewater, and the ratio C / C0 of the SMX concentration to its initial concentration was calculated. In this example, a total of 4 groups of experiments were carried out, and the wastewaters in each group of experiments contained different types of anions, specifically including Clˉ, NO3ˉ, H2PO4ˉ, HCO3ˉ, and the concentration of the anions was 0.2 mmol / L. The SMX aqueous solution without adding anions was used as the control group. The results are as Figure 8 shown.

[0068] As Figure 8 can be seen, different water matrices have different inhibitory effects on the degradation of pollutants. For the B-ZVI B2O3 / PAA system, the effects of Clˉ and NO3ˉ are the smallest, and they basically have no effect on the degradation of pollutants; for the B-ZVI H3BO3 / PAA system, the effect of Clˉ is the smallest; for the B-ZVI Na2B4O7For the / PAA system, the influence of H2PO4ˉ is the smallest, and it has basically no influence on the degradation of pollutants. The three systems are relatively more affected by HCO3ˉ. However, considering that the concentration of the water matrix in actual water bodies is generally lower than 0.2 mmol / L, overall, the three systems of the present invention can exhibit good resistance to the influence of the water matrix in actual water bodies, that is, the three systems have good tolerance to the water matrix in actual water bodies. Appropriate micron-scale boronized zero-valent iron (B-ZVI B2O3 、B-ZVI H3BO3 or B-ZVI Na2B4O7 ) can be selected as the catalyst.

[0069] Example 6

[0070] The stability and reusability of the catalyst are important factors for evaluating the performance of the catalyst and also an important prerequisite for whether the wastewater treatment method can be applied on a large scale in practice. Therefore, in this example, the stability and reusability of the micron-scale boronized zero-valent iron prepared in Example 1 are tested.

[0071] (1) Using the micron-scale boronized zero-valent iron (B-ZVI B2O3 、B-ZVI H3BO3 or B-ZVI Na2B4O7 ) prepared in Example 1 as the catalyst, the catalyst and PAA are added to an SMX aqueous solution (simulated wastewater) with an SMX concentration of 10 μmol / L, controlling the concentration of the catalyst in the wastewater to be 100 mg / L and the concentration of PAA in the wastewater to be 0.2 mmol / L, and treating for 30 min under the conditions of 25 °C and a rotation speed of 300 r / min. During the wastewater treatment process, samples are taken at regular intervals to measure the concentration of SMX in the wastewater, and the ratio C / C0 of the SMX concentration to its initial concentration is calculated.

[0072] (2) After each reaction for 30 min, replace the new wastewater same as that in step (1), repeat the operation in step (1) for wastewater treatment, and recycle the micron-scale boronized zero-valent iron (B-ZVI B2O3 、B-ZVI H3BO3 or B-ZVI Na2B4O7 ) in step (1), and recycle it a total of 7 times.

[0073] Figure 9 Figures (a), (b), and (c) are the test results of the recycling performance when using B-ZVI B2O3 、B-ZVI H3BO3 or B-ZVI Na2B4O7 as the catalyst. As can be seen from Figure 9 , B-ZVI B2O3After 7 cycles, the removal rate of SMX basically remained unchanged; B-ZVI H3BO3 After 3 cycles, the removal rate of SMX basically remained unchanged. After 6 cycles, the removal rate of SMX could still be maintained at a level above 90%. After 7 cycles, the removal rate of SMX remained at a level above 80%, indicating that B-ZVI H3BO3 also had good recyclability; for B-ZVI Na2B4O7 however, its recyclability decreased rapidly. After 4 cycles, the removal rate of SMX was only about 50%. The above experimental results show that B-ZVI B2O3 and B-ZVI H3BO3 had excellent stability and recyclability, and using the two to catalytically activate PAA to degrade pollutants in wastewater was a highly stable and promising wastewater treatment method.

[0074] Example 7

[0075] In this example, a series of iron boride-based materials were prepared with different molar ratios of boron to iron, that is, a series of micron-sized zero-valent iron boride (B-ZVI) with different ratios of boron to iron were prepared as follows:

[0076] According to the molar ratio of boron to iron of 0.01:1, micron-sized zero-valent iron and boron oxide were added to the ball mill tank of a planetary ball mill, grinding balls were added, and ball milling was carried out at a speed of 500 rpm for 5 h to obtain zero-valent iron boride, denoted as B-ZVI(0.01).

[0077] According to the molar ratio of boron to iron of 0.02:1, micron-sized zero-valent iron and boron oxide were added to the ball mill tank of a planetary ball mill, grinding balls were added, and ball milling was carried out at a speed of 500 rpm for 5 h to obtain zero-valent iron boride, denoted as B-ZVI(0.02).

[0078] According to the molar ratio of boron to iron of 0.01:1, micron-sized zero-valent iron and boron oxide were added to the ball mill tank of a planetary ball mill, grinding balls were added, and ball milling was carried out at a speed of 500 rpm for 5 h to obtain zero-valent iron boride, denoted as B-ZVI(0.03).

[0079] According to the molar ratio of boron to iron of 0.01:1, micron-sized zero-valent iron and boron oxide were added to the ball mill tank of a planetary ball mill, grinding balls were added, and ball milling was carried out at a speed of 500 rpm for 5 h to obtain zero-valent iron boride, denoted as B-ZVI(0.04).

[0080] According to the molar ratio of boron to iron of 0.01:1, micron-scale zero-valent iron and boron oxide were added to the ball-milling tank of a planetary ball mill, grinding balls were added, and ball-milled at a speed of 500 rpm for 5 h to obtain boronized zero-valent iron, denoted as B-ZVI(0.05).

[0081] According to the molar ratio of boron to iron of 0.01:1, micron-scale zero-valent iron and boron oxide were added to the ball-milling tank of a planetary ball mill, grinding balls were added, and ball-milled at a speed of 500 rpm for 5 h to obtain boronized zero-valent iron, denoted as B-ZVI(0.08).

[0082] The prepared micron-scale boronized zero-valent iron (B-ZVI(0.01), B-ZVI(0.02), B-ZVI(0.03), B-ZVI(0.04), B-ZVI(0.05), B-ZVI(0.08)) and PAA were respectively added to an SMX aqueous solution (simulated wastewater, pH about 7) with an SMX concentration of 10 μmol / L. The concentration of micron-scale boronized zero-valent iron in the wastewater was controlled to be 100 mg / L, and the concentration of PAA in the wastewater was 0.2 mmol / L. Treatment was carried out at 25 °C and a rotation speed of 300 r / min for 20 min. During the wastewater treatment process, samples were taken at regular intervals to measure the concentration of SMX in the wastewater, and the ratio C / C0 of the SMX concentration to its initial concentration was calculated.

[0083] As a control, the ZVI and PAA prepared in Comparative Example 1 were added to an SMX aqueous solution with an SMX concentration of 10 μmol / L. The concentration of ZVI and S-ZVI in the wastewater was controlled to be 100 mg / L, and the concentration of PAA in the wastewater was 0.2 mmol / L. Treatment was carried out at 25 °C and a rotation speed of 300 r / min for 20 min. During the wastewater treatment process, samples were taken at regular intervals to measure the concentration of SMX in the wastewater, and the ratio C / C0 of the SMX concentration to its initial concentration was calculated.

[0084] Figure 10 shows the change of C / C0 with the wastewater treatment time when different catalysts were used to catalytically activate PAA to degrade SMX in this example. Figure 10It can be seen that, compared with the ZVI prepared in Comparative Example 1, the performance of the micron-scale zero-valent iron boride prepared in this example in catalytically activating PAA to degrade SMX is significantly better, indicating that the introduction of an appropriate amount of non-metallic element boron improves the ability of zero-valent iron to catalytically activate PAA. At the same time, the ability of the micron-scale zero-valent iron boride prepared by feeding materials in different molar ratios to catalytically activate PAA is different. When the molar ratio of boron to iron in the feed is 0.02, the prepared micron-scale zero-valent iron boride has the strongest ability to catalytically activate PAA to degrade organic pollutants. When the molar ratio of boron to iron in the feed is 0.02 - 0.08, the prepared micron-scale zero-valent iron boride also has good ability to catalytically activate PAA to degrade organic pollutants.

[0085] Example 8

[0086] In this example, the influence of the pH value of the wastewater containing organic pollutants on the degradation of organic pollutants was investigated. Specifically, SMX aqueous solutions with different pH values were used as simulated wastewater, and the removal ability of the method of the present invention for SMX in the simulated wastewater was investigated.

[0087] The micron-scale zero-valent iron boride B-ZVI(0.02) prepared in Example 7 and PAA were added to an SMX aqueous solution (simulated wastewater) with an SMX concentration of 10 μmol / L. The concentration of the micron-scale zero-valent iron boride in the wastewater was controlled to be 100 mg / L, and the concentration of PAA in the wastewater was 0.2 mmol / L. The treatment was carried out for 15 min at 25 °C and a rotation speed of 300 r / min. During the wastewater treatment process, samples were taken at regular intervals to measure the concentration of SMX in the wastewater, and the ratio C / C0 of the SMX concentration to its initial concentration was calculated. A total of 5 groups of experiments were carried out in this example, and the pH values of the SMX solutions in each group of experiments were 3, 5, 7, 9, and 11 respectively. The results are as Figure 11 shown.

[0088] As Figure 11 can be seen, when the pH value of the simulated wastewater is in the range of 3 - 9, the method of the present invention can achieve complete removal of SMX in the simulated wastewater within 15 min, and within this pH value range, the influence of the pH value of the wastewater on the removal rate of organic pollutants is not obvious.

[0089] Example 9

[0090] The micron-scale boronized zero-valent iron B-ZVI(0.05) prepared in Example 7 and PAA were added to an SMX aqueous solution (simulated wastewater) with an SMX concentration of 30 μmol / L (adjust the pH value to 3). The concentration of micron-scale boronized zero-valent iron in the wastewater was controlled at 150 mg / L, and the concentration of PAA in the wastewater was 0.4 mmol / L. It was treated for 15 min under the conditions of 25 °C and a rotation speed of 300 r / min. At the end of the treatment, samples were taken to measure the concentration of SMX in the wastewater, and the ratio C / C0 of the SMX concentration to its initial concentration was calculated. The results showed that the removal rate of SMX in the simulated wastewater was over 99%.

[0091] Example 10

[0092] The micron-scale boronized zero-valent iron B-ZVI(0.03) prepared in Example 7 and PAA were added to an SMX aqueous solution (simulated wastewater) with an SMX concentration of 15 μmol / L. The concentration of micron-scale boronized zero-valent iron in the wastewater was controlled at 50 mg / L, and the concentration of PAA in the wastewater was 0.1 mmol / L. It was treated for 30 min under the conditions of 25 °C and a rotation speed of 300 r / min. At the end of the treatment, samples were taken to measure the concentration of SMX in the wastewater, and the ratio C / C0 of the SMX concentration to its initial concentration was calculated. The results showed that the removal rate of SMX in the simulated wastewater was over 98%.

Claims

1. A method for efficiently catalyzing peracetic acid to treat pollutants with an iron boride-based material, characterized in that, It includes the following steps: Adding micron-scale zero-valent iron boride and peracetic acid to the wastewater containing organic pollutants, treating the wastewater under stirring conditions, controlling the concentration of micron-scale zero-valent iron boride in the wastewater to be 50 - 150 mg / L, and the concentration of peracetic acid in the wastewater to be 0.1 - 0.4 mmol / L; during the wastewater treatment process, the micron-scale zero-valent iron boride catalytically activates peracetic acid to generate hydroxyl radicals, organic radicals CH3C(O)O· and CH3C(O)OO· to degrade the organic pollutants in the wastewater; after completing the treatment of a batch of wastewater, recycling the micron-scale zero-valent iron boride for the treatment of the next batch of wastewater; The micron-sized zero-valent iron boride is prepared by fully ball-milling a boron precursor and micron-sized zero-valent iron. The iron species in the micron-sized zero-valent iron boride include Fe(II), Fe(III), and Fe 0 , and the boron species include boron oxides and FeB. The boron precursor is at least one of boron oxide and boric acid.

2. The method for efficiently catalyzing peracetic acid to treat pollutants with the iron boride-based material according to claim 1, characterized in that The preparation method of the micron-scale zero-valent iron boride is: mixing a boron precursor and micron-scale zero-valent iron according to a molar ratio of boron to iron of (0.01 - 0.08):1, and then ball-milling for at least 4 h to obtain it.

3. The method for efficiently catalyzing peracetic acid to treat pollutants by the iron boride-based material according to claim 2, wherein The particle size of the micron-scale zero-valent iron boride is 100 - 500 μm.

4. The method for efficiently catalyzing peracetic acid to treat pollutants with the iron boride-based material according to claim 2, wherein Ball-milling at a rotation speed of 400 - 800 rpm for 4 - 6 h to obtain the micron-scale zero-valent iron boride.

5. The method for efficiently catalyzing peracetic acid to treat pollutants by the iron boride-based material according to any one of claims 1 to 4, characterized in that, Controlling the number of recycling times of the micron-scale zero-valent iron boride to be at least 7 times.

6. The method for efficiently catalyzing peracetic acid to treat pollutants with the iron boride-based material according to claim 5, wherein, Controlling the number of recycling times of the micron-scale zero-valent iron boride to be 7 - 12 times.

7. The method for efficiently catalyzing peracetic acid to treat pollutants with the iron boride-based material according to any one of claims 1 to 4, characterized in that, The pH value of the wastewater containing organic pollutants is between 3 and 9.

8. The method for efficiently catalyzing peracetic acid to treat pollutants by the iron boride-based material according to any one of claims 1 to 4, characterized in that, Determining the wastewater treatment time according to the water quality of the wastewater containing organic pollutants.

9. The method for efficiently catalyzing peracetic acid to treat pollutants by the iron boride-based material according to any one of claims 1 to 4, characterized in that, The wastewater containing organic pollutants also contains at least one of Clˉ, NO3ˉ, and H2PO4ˉ.

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