Phosphated micron zero-valent iron enhanced by liquid nitrogen freezing treatment, and preparation method and application thereof

Abstract

The application discloses phosphatized micron zero-valent iron which is strengthened by liquid nitrogen freezing treatment, and a preparation method and application thereof. The phosphatized micron zero-valent iron is obtained by mixing micron zero-valent iron powder and a phosphatized precursor and ball milling through a mechanochemical method, and the phosphatized micron zero-valent iron is subjected to low-temperature freezing by liquid nitrogen to obtain the phosphatized micron zero-valent iron which is strengthened by liquid nitrogen freezing treatment. The phosphatized micron zero-valent iron which is strengthened by liquid nitrogen freezing treatment has high removal efficiency for heavy metal-organic reagent complex in mine wastewater and strong cyclic reactivity, realizes one-stop removal of heavy metals and synchronous degradation of organic ligands, and does not need to add an oxidant and a precipitant; the preparation process is simple, environment-friendly and low in cost, and the phosphatized micron zero-valent iron which is strengthened by liquid nitrogen freezing treatment is expected to be practically applied to treatment of mine wastewater which is polluted by heavy metal-organic reagent complex.

Description

Technical Field

[0001] This invention belongs to the field of heavy metal-organic beneficiation agent complex pollution control technology, specifically relating to a liquid nitrogen cryogenic treatment-enhanced phosphorylated micron-sized zero-valent iron, its preparation method, and its application. Background Technology

[0002] The rapid development of the mining industry generates a large amount of mine wastewater, which often contains harmful heavy metal ions (such as Cu). 2+ Heavy metal ions containing empty orbitals (such as Lewis acids) readily coordinate with organic agents containing lone pairs of electrons (such as benzyl hydroxyxamic acid, BHA) to form heavy metal complexes. Residual organic agents in mine wastewater, if discharged directly without treatment, cause organic pollution to the environment. Furthermore, heavy metal complexes exhibit higher stability and mobility, making their harm to the environment and health even more severe. In addition, direct reuse of untreated mine wastewater will seriously affect mineral processing efficiency. Moreover, heavy metal complexes are difficult to remove effectively using traditional methods (such as adsorption and precipitation), thus urgently requiring the development of efficient methods for removing heavy metal complexes.

[0003] The treatment of heavy metal complex pollution requires the simultaneous removal of heavy metal ions and degradation of organic ligands. Simple decomposition cannot remove organic ligands and requires additional steps to remove heavy metal ions, while simple oxidative degradation can only remove organic ligands. Therefore, there is an urgent need to develop an effective method that can simultaneously remove heavy metal ions and degrade organic ligands. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a phosphorylated micron-sized zero-valent iron (P-ZVI) enhanced by liquid nitrogen cryogenic treatment. bm&ln ) and its preparation methods and applications.

[0005] Zero-valent iron (ZVI) has attracted widespread attention in the field of environmental pollution control due to its advantages such as environmental friendliness, cost-effectiveness, and high reactivity. However, a (hydro)oxide passivation layer easily forms on the surface of ZVI, which hinders the release and transfer of electrons, thus greatly reducing its reactivity. Modification of ZVI is expected to overcome this passivation layer barrier, making it a promising candidate for one-stop removal of heavy metals and their complexed organic ligands from mine wastewater. A key strategy for ZVI modification is to increase the surface ferrous (≡Fe) content. 2+ The active sites can then activate hydrogen peroxide (H2O2), dissolved oxygen (O2), persulfate (PS), sodium chlorite (NaClO2), etc., to generate free radicals such as hydroxyl radicals (·OH) and singlet oxygen (·OH). 1 O2), sulfate free radicals (SO4) ·- ), high-priced iron (Fe)V / Fe IV Dissolved oxygen, as a green oxidant, can be activated to generate reactive oxygen species (ROS) that oxidize and degrade organic ligands without the need for additional oxidants, thus reducing costs. Furthermore, the removal of heavy metal ions by zero-valent iron primarily relies on the reduction and fixation of heavy metal ions by elemental iron; therefore, modification of zero-valent iron can improve the surface ferrous (≡Fe) content. 2+ While considering the content of active sites, it is also necessary to ensure that more internal iron cores (Fe) are exposed. 0 This improves its ability to remove heavy metal ions.

[0006] The ferrous phosphate shell formed by phosphorylation modification of zero-valent iron gives it more surface ferrous (≡Fe) content. 2+ The presence of active sites significantly promotes the activation of dissolved oxygen and the generation of reactive oxygen species (ROS), thereby efficiently oxidizing and degrading, and even oxidizing and mineralizing, organic agents (heavy metal complexing ligands). The significance of liquid nitrogen cryotherapy lies in its ability to create cracks in phosphorylated micron-sized zero-valent iron, thereby exposing more internal zero-valent iron cores (Fe). 0 This will significantly enhance its reduction and fixation of heavy metal ions. Simultaneously, more exposed elemental iron readily reacts with the ferric ions dissolved from activated dissolved oxygen, undergoing a disproportionation reaction (Fe...). 0 +2Fe 3+ →3Fe 2+ This regenerates surface ferrous iron, overcoming the bottleneck in ferrous iron regeneration through efficient iron cycling, thereby greatly improving the cycling reaction capacity. Phosphorylation modification and liquid nitrogen freezing treatment expose more surface ferrous iron (≡Fe). 2+ ) and elemental iron (Fe 0 This significantly improved the phosphorylated micron-sized zero-valent iron (P-ZVI) enhanced by liquid nitrogen cryogenic treatment. bm&ln The comprehensive performance of removing typical heavy metal-organic metallurgical reagent complexes (copper benzoyl hydroxamic acid complex, Cu(II)-BHA) and actual mine wastewater (containing organic reagents and heavy metals).

[0007] The technical solution adopted in this invention is:

[0008] A method for preparing phosphorylated micron-sized zero-valent iron enhanced by liquid nitrogen cryogenic treatment includes the following steps:

[0009] Phosphorylated micron-sized zero-valent iron powder was obtained by ball milling a mixture of micron-sized zero-valent iron powder and a phosphorylation precursor using a mechanochemical method. The phosphorylated micron-sized zero-valent iron was then cryogenically frozen with liquid nitrogen to obtain phosphorylated micron-sized zero-valent iron enhanced by liquid nitrogen cryogenic treatment.

[0010] Preferably, the phosphorylation precursor includes at least one of sodium dihydrogen phosphate, potassium dihydrogen phosphate, phosphoric acid, sodium monohydrogen phosphate, potassium monohydrogen phosphate, sodium phosphate, and potassium phosphate.

[0011] Preferably, the molar ratio of the phosphorylated precursor to micron-sized zero-valent iron powder (based on the molar amount of iron) is 0.01–0.1:1 (0.01:1, 0.02:1, 0.03:1, 0.04:1, 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, 0.10:1).

[0012] More preferably, the optimal molar ratio of the phosphorylated precursor to micron-sized zero-valent iron powder is 0.07:1.

[0013] Preferably, the particle size of the micron-sized zero-valent iron powder is 80–300 μm.

[0014] More preferably, the particle size of the micron-sized zero-valent iron powder is 60–120 μm.

[0015] Preferably, the micron-sized zero-valent iron powder is industrial iron powder. Industrial iron powder is inexpensive (approximately 12 yuan / kg), and its main components include elemental iron and iron (hydrogen) oxides.

[0016] Preferably, the ball milling is a mechanical ball milling;

[0017] Preferably, the stainless steel grinding balls used in the ball mill have a diameter of 0.4–0.6 cm and 1.0–1.2 cm.

[0018] More preferably, the stainless steel grinding balls used in the ball mill have diameters of 0.6 cm and 1.0 cm.

[0019] Preferably, the ball mill rotates at a speed of 400–800 rpm, and the milling time is 1–5 hours.

[0020] More preferably, the ball mill operates at a speed of 500 rpm and the milling time is 4 hours.

[0021] Preferably, the cryogenic freezing is performed by immersion in liquid nitrogen;

[0022] Preferably, the cryogenic freezing time is 10 to 15 minutes.

[0023] More preferably, the cryogenic freezing time is 10 minutes.

[0024] The above-described preparation method yields phosphorylated micron-sized zero-valent iron enhanced by liquid nitrogen cryogenic treatment.

[0025] The above-mentioned application of phosphorylated micron-sized zero-valent iron enhanced by liquid nitrogen freezing treatment in the treatment of wastewater containing heavy metals and / or organic matter. It can activate dissolved oxygen to generate reactive oxygen species (ROS) to oxidize, degrade, and even mineralize organic agents (complexed ligands), while efficiently removing heavy metal ions and exhibiting good cycle reaction stability.

[0026] Preferably, the wastewater containing heavy metals and / or organic matter is wastewater containing heavy metal complexes.

[0027] More preferably, the heavy metal complex is copper benzo(II)-BHA.

[0028] Preferably, the wastewater containing heavy metals and / or organic matter is actual mine wastewater containing organic reagents and heavy metals.

[0029] Preferably, the treatment of wastewater containing heavy metals and / or organic matter is carried out on a shaker at 220 rpm for 1 hour.

[0030] Preferably, the concentration of copper benzo(II)-BHA, a heavy metal complex pollutant removed from the simulated mine wastewater, is 0.2 mmol / L, without adding reagents to adjust the pH, or adding any additional oxidants or precipitants.

[0031] A method for treating wastewater contaminated with heavy metal complexes from simulated mining wastewater includes the following steps:

[0032] 0.5g of phosphorylated micron-sized zero-valent iron (P-ZVI) enhanced by liquid nitrogen cryotreatment was used. bm&ln A batch treatment experiment was conducted by adding 100 mL of copper benzo(II)-BHA complex.

[0033] The beneficial effects of this invention are:

[0034] The present invention provides a liquid nitrogen cryogenically enhanced phosphorylated micron-sized zero-valent iron (P-ZVI) bm&ln This technology can remove copper benzoate complex, a typical heavy metal-organic metallurgical complex, in a one-stop process. It effectively mineralizes the organic ligand while efficiently removing heavy metal ions, exhibiting high reaction efficiency and strong recyclability. P-ZVI bm&ln It can efficiently treat actual mine wastewater containing organic agents and heavy metals, and the treatment results meet the national emission standards. At the same time, it significantly reduces the ecotoxicity of the wastewater. Moreover, the material preparation process is simple, the production cost is low, and it is environmentally friendly. It has a very broad application prospect in the field of heavy metal complex pollution control of mine wastewater.

[0035] Specifically:

[0036] 1) The phosphorylated micron-sized zero-valent iron enhanced by liquid nitrogen freezing in this invention has an abundant surface ferrous (≡Fe) layer formed during the phosphorylation process. 2+ The active site significantly enhances its ability to activate dissolved oxygen and the production of reactive oxygen species (ROS), thereby improving its performance in oxidizing and degrading organic agents. It also effectively mineralizes and removes complexing ligands, avoiding the risk of complexation.

[0037] 2) The phosphorylation modification of zero-valent iron in this invention can significantly enhance its surface ferrous (≡Fe) content. 2+ The content of active sites, and the amount of phosphate ions (PO4) contained therein. 3- It can help remove heavy metal ions through adsorption and precipitation.

[0038] 3) In the process of liquid nitrogen freezing treatment of phosphorylated zero-valent iron in this invention, the low-temperature freezing of liquid nitrogen immersion can cause the surface to crack, thereby exposing more of the internal iron core (Fe). 0 This will significantly enhance its reduction and fixation of heavy metal ions. Simultaneously, more exposed elemental iron readily reacts with the ferric ions dissolved from activated dissolved oxygen, undergoing a disproportionation reaction (Fe...). 0 +2Fe 3+ →3Fe 2+ By regenerating ferrous iron through efficient iron recycling, the recycling reactivity is greatly improved. Attached Figure Description

[0039] Figure 1 This is a schematic diagram illustrating the mechanism of phosphorylated micron-sized zero-valent iron treatment for benzohydroxyoxime acid complexing with copper, enhanced by liquid nitrogen freezing treatment according to the present invention.

[0040] Figure 2 X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA & DTG) were performed on the ball-milled micron zero-valent iron, liquid nitrogen-frozen ball-milled micron zero-valent iron, phosphorylated ball-milled micron zero-valent iron, and liquid nitrogen-frozen phosphorylated ball-milled micron zero-valent iron in Examples 1-4.

[0041] Figure 3 Mössbauer's method for liquid nitrogen-crystallized ball-milled micron-sized zero-valent iron and liquid nitrogen-crystallized phosphorylated ball-milled micron-sized zero-valent iron in Examples 3 and 4. Spectral analysis.

[0042] Figure 4 Selected area electron diffraction (SAED), high-resolution transmission electron microscopy and energy dispersive spectroscopy (HR-TEM&EDS), and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were used to analyze the phosphorylated micron-sized zero-valent iron enhanced by liquid nitrogen freezing treatment in Example 4.

[0043] Figure 5Atomic force microscopy (AFM) and potential analysis of phosphorylated micron-sized zero-valent iron enhanced by liquid nitrogen freezing treatment in Example 4.

[0044] Figure 6 High-resolution X-ray photoelectron spectroscopy (HR-XPS) analysis of ball-milled micron zero-valent iron, phosphorylated ball-milled micron zero-valent iron, and phosphorylated ball-milled micron zero-valent iron enhanced by liquid nitrogen cryogenic treatment in Examples 1, 3, and 4.

[0045] Figure 7 Density functional theory (DFT) calculations were performed on zero-valent iron and phosphorylated zero-valent iron before and after phosphoric acid modification and their potential to activate molecular oxygen in Examples 1-4.

[0046] Figure 8 The images show the effects of treating benzohydroxyxamic acid complexed copper with ball-milled micron zero-valent iron, ball-milled micron zero-valent iron frozen in liquid nitrogen, phosphorylated ball-milled micron zero-valent iron, and phosphorylated ball-milled micron zero-valent iron frozen in liquid nitrogen as described in Examples 1-4.

[0047] Figure 9 The effect of treating benzyl hydroxamic acid complexed with copper by ball milling micron-sized zero-valent iron with liquid nitrogen cryogenic treatment of ferrous phosphate, ferric phosphate, sodium dihydrogen phosphate or ferrous sulfate heptahydrate.

[0048] Figure 10 The diagram shows the effect of continuous cyclic treatment of benzohydroxyxamic acid complexed copper using ball-milled micron zero-valent iron, ball-milled micron zero-valent iron frozen in liquid nitrogen, phosphorylated ball-milled micron zero-valent iron, and phosphorylated ball-milled micron zero-valent iron frozen in liquid nitrogen in Examples 1-4.

[0049] Figure 11 This is a diagram illustrating the effect of treating actual wastewater with phosphorylated ball-milled micron-sized zero-valent iron using liquid nitrogen freezing, as described in Example 4.

[0050] Figure 12 The images show the effects of treating benzyl hydroxamic acid complexed with copper using liquid nitrogen-crystallized ball-milled micron-sized zero-valent iron in Examples 5 and 6. Detailed Implementation

[0051] The present invention will be further explained and described below with reference to specific embodiments.

[0052] The industrial zero-valent iron powder used in the following examples has a particle size of 60–120 μm.

[0053] Example 1:

[0054] A ball-milled micron-sized zero-valent iron, prepared by the following method:

[0055] Twenty 1cm diameter stainless steel grinding balls and fifty 0.6cm diameter stainless steel grinding balls were added to a stainless steel grinding jar and purged with argon (Ar) for 3 minutes. Then, 5.0g of industrial zero-valent iron powder was added and mixed thoroughly. The grinding jar was then placed in a planetary ball mill, and the mill speed was adjusted to 500rpm. The mill was run for 4 hours (with the running direction changed every hour) to obtain ball-milled micron-sized zero-valent iron (denoted as ZVI). bm ).

[0056] Example 2:

[0057] A phosphorylated micron-sized zero-valent iron is prepared by the following method:

[0058] Twenty 1cm diameter stainless steel grinding balls and fifty 0.6cm diameter stainless steel grinding balls were added to a stainless steel grinding jar and purged with argon (Ar) for 3 minutes. Then, 5.0g of industrial zero-valent iron powder and 0.75g of sodium dihydrogen phosphate (NaH2PO4) were added and mixed thoroughly (the molar ratio of sodium dihydrogen phosphate to iron was 0.07:1). The grinding jar was then placed in a planetary ball mill, and the mill speed was adjusted to 500 rpm. The mill was run for 4 hours (changing the running direction every hour) to obtain phosphorylated micron-sized zero-valent iron (denoted as P-ZVI). bm ).

[0059] Example 3:

[0060] A method for preparing ball-milled micron-sized zero-valent iron subjected to liquid nitrogen cryogenic treatment is as follows:

[0061] Twenty 1cm diameter stainless steel grinding balls and fifty 0.6cm diameter stainless steel grinding balls were added to a stainless steel grinding jar and purged with argon (Ar) for 3 minutes. Then, 5.0g of industrial zero-valent iron powder was added and mixed thoroughly. The grinding jar was then placed in a planetary ball mill, and the mill speed was adjusted to 500rpm. The mill was run for 4 hours (with the running direction changed every hour) to obtain micron-sized zero-valent iron.

[0062] After removing the grinding balls from the grinding jar, liquid nitrogen is added to the jar, and the mixture is immersed and frozen for 10 minutes to obtain ball-milled micron-sized zero-valent iron (denoted as ZVI) treated with liquid nitrogen freezing. bm&ln ).

[0063] Example 4:

[0064] A method for preparing phosphorylated micron-sized zero-valent iron enhanced by liquid nitrogen cryogenic treatment is as follows:

[0065] Twenty stainless steel grinding balls with a diameter of 1 cm and fifty stainless steel grinding balls with a diameter of 0.6 cm were added to a stainless steel grinding jar and purged with argon (Ar) for 3 minutes. Then, 5.0 g of industrial zero-valent iron powder and 0.75 g of sodium dihydrogen phosphate (NaH2PO4) were added and mixed evenly (the molar ratio of sodium dihydrogen phosphate to iron was 0.07:1). The grinding jar was then placed in a planetary ball mill, and the speed of the ball mill was adjusted to 500 rpm. The mill was run for 4 hours (the running direction was changed every hour) to obtain phosphorylated micron-sized zero-valent iron.

[0066] After removing the grinding beads from the grinding jar, liquid nitrogen was added to the jar, and the mixture was immersed and frozen for 10 minutes to obtain phosphorylated micron-sized zero-valent iron (denoted as P-ZVI) enhanced by liquid nitrogen freezing treatment. bm&ln ).

[0067] This invention relates to phosphorylated micron-sized zero-valent iron (P-ZVI) enhanced by liquid nitrogen cryogenic treatment. bm&ln The mechanism diagram for treating copper complex (Cu(II)-BHA) of benzyl hydroxamic acid is shown below. Figure 1 As shown.

[0068] ZVI in Examples 1-4 bm ZVI bm&ln P-ZVI bm and P-ZVI bm&ln A series of characterizations and density functional theory (DFT) calculations, such as Figures 2-7 As shown.

[0069] Depend on Figure 2 From (a) we can see that: ZVI bm ZVI bm&ln P-ZVI bm and P-ZVI bm&ln The XRD peaks of the sample matched the standard XRD pattern card for iron (Fe 06-0696), indicating that ball milling phosphorylation modification and liquid nitrogen freezing treatment did not change the main crystal form of zero-valent iron; its main crystal form remained zero-valent iron. Figure 2 (b) P-ZVI bm&ln The FT-IR analysis results show that its wavelengths at 1018.4, 1631.7, and 3442.8 cm⁻¹ are optimal. -1 The infrared peak at this location matches well with the infrared peaks of ferrous phosphate and ferric phosphate, and also coincides with the peaks at 555.5 and 1384.8 cm⁻¹. -1 The infrared peak at [location] matches well with ferrous phosphate but poorly with ferric phosphate, indicating that ferrous phosphate may have been generated during the phosphorylation modification of zero-valent iron. Furthermore, the strongest infrared peak in the DFT-calculated infrared spectrum matches well with the observed peak, verifying the reliability of the model used in subsequent DFT calculations. Figure 2 P-ZVI in (c) bm&lnThermogravimetric analysis and differential analysis of ferrous phosphate show that: P-ZVI bm&ln The thermogravimetric analysis curves showed good agreement with those of ferrous phosphate, indicating that P-ZVI... bm&ln It may contain ferrous phosphate.

[0070] Depend on Figure 3 (a) ZVI bm&ln of Spectral analysis shows that: ZVI bm&ln The main components and their proportions are: elemental iron (89.7%), basic ferric oxide (7.9%), and ferrous oxide (2.4%). Figure 3 (b) P-ZVI bm &ln of Spectral analysis shows that: P-ZVI bm&ln The main components and their proportions are elemental iron (90.7%), ferrous phosphate (6.6%), and ferric phosphate (2.7%), which verifies the ferrous phosphate generated during the phosphoric acid modification process.

[0071] Depend on Figure 4 (a) P-ZVI bm&ln SAED analysis revealed diffraction patterns belonging to iron (2 0 0), (001), and (2 1 1), as well as diffraction patterns belonging to ferrous phosphate (3 1 0) and (0 0 1), indicating that phosphorylation modification of zero-valent iron resulted in the formation of ferrous phosphate. Figure 4 (b) P-ZVI bm&ln TEM & EDS analysis results showed that P-ZVI bm&ln It has a phosphorus-rich shell, approximately 50–100 nm thick. Figure 4 P-ZVI in (c) bm&ln The ToF-SIMS and its 3D depth profile test show that the thickness of its ferrous phosphate shell is about 50 nm.

[0072] Depend on Figure 5 P-ZVI bm&ln AFM and potential analysis revealed that liquid nitrogen freezing treatment resulted in cracks with a width of approximately 173.2–463.1 nm and a depth of approximately 72.0–81.2 nm, potentially exposing more internal zero-valent iron cores (Fe). 0 Meanwhile, the potential analysis results show that the potential deep within the crack is lower than that at the surface, which is conducive to the migration of electrons from the interior to the surface.

[0073] Depend on Figure 6 (a)ZVI bm and (b)P-ZVI bm and (c)P-ZVIbm&ln HR-XPS (Fe 2p) analysis showed that phosphorylation modification significantly increased the content of ferrous iron on the surface, and liquid nitrogen freezing treatment significantly increased the content of elemental iron on the surface.

[0074] Depend on Figure 7 Density functional theory (DFT) calculations before and after zero-valent iron phosphate modification (a) show that phosphoric acid modification significantly reduces the O2 adsorption energy, which will promote dissolved oxygen adsorption. Meanwhile, Mulliken and Hirshfeld charge analysis indicates that the O2 adsorbed by P-ZVI carries a higher charge and is more easily activated. Bond length analysis reveals the O2 O2 bond length in the P-ZVI system. Longer than the O2 bond length in the ZVI system This indicates its antibonding molecular orbitals (π) * 2p O2 may be generated because more electrons may be filled on the surface. ·- or O2 2- This verified the activation of O2 in the P-ZVI system. Phosphorylation modification increases the highest occupied molecular orbital (HOMO) energy level of P-ZVI, which will facilitate electron release, while the band gap (E) is reduced. LUMO -E HOMO The decrease in the p-ZVI work function will promote electron migration, and the decrease in the p-ZVI work function will promote the contribution of electrons. Figure 7 The differential charge density analysis of (b) and (c) shows that phosphorylation modification promotes electron transfer between P-ZVI and O2, which will be beneficial to the activation of dissolved oxygen and the generation of reactive oxygen species (ROS).

[0075] Further testing of material properties: 0.5g of ZVI from Examples 1-4 was tested. bm ZVI bm&ln P-ZVI bm and P-ZVI bm&lnThe solution was added to 100 mL of a 0.2 mmol / L copper benzo(II)-BHA solution and then shaken at 220 rpm for 1 h. Samples were taken at 15, 30, 45, and 60 min and filtered through a 0.22 μm filter before analysis. Removal of heavy metal complexes requires simultaneous capture of heavy metals and degradation of organic ligands. If only the organic ligands are destroyed without deep oxidative degradation, residual organic intermediates will remain, potentially causing environmental pollution due to their toxicity, and there is also a risk of complexation. Therefore, this study aims to achieve the full oxidative degradation and even mineralization of organic flotation reagents (organic ligands) while simultaneously removing heavy metals. Total organic carbon (TOC) analyzer was used to determine the TOC removal rate, which effectively reflects the degree of oxidative degradation of organic ligands in the heavy metal complex system, thereby evaluating the degradation effect of the organic reagent BHA. Simultaneously, the residual concentration of total copper was determined using atomic absorption spectrometry (AAS). Both methods have been verified to exhibit excellent linearity.

[0076] Removal effect as Figure 8 As shown in (a) and (b): ZVI bm and ZVI bm&ln The system's TOC removal rate is less than 1.5%, and it can hardly degrade the organic ligands in Cu(II)-BHA, but it can remove 0.89.0% and 90.1% of total Cu, respectively. Phosphorylated micron-sized zero-valent iron (P-ZVI) bm The system significantly reduced TOC, degraded ca. 79.5% of BHA, and removed ca. 90.0% of total Cu. Liquid nitrogen cryogenic treatment enhanced phosphorylated micron-sized zero-valent iron (P-ZVI) bm&ln The system significantly reduced the TOC in Cu(II)-BHA, degrading ca. 85.3% of organic ligands while simultaneously removing ca. 100% of total copper. Figure 8 As shown in (a) and (b), zero-valent iron phosphorylation significantly improves the performance of degrading organic drug ligands, while liquid nitrogen freezing treatment significantly improves the ability to remove heavy metal ions. P-ZVI bm&ln It exhibits excellent removal efficiency of copper benzo(II)-BHA complex, achieving simultaneous degradation of organic reagent ligands and removal of heavy metal ions.

[0077] in addition, Figure 9 In ZVI bm&lnThe reaction system was supplemented with either ferrous phosphate (0.223 g, n(P):n(ZVI) = 7%) or ferric phosphate (0.094 g, n(P):n(ZVI) = 7%), or sodium dihydrogen phosphate (0.075 g, n(P):n(ZVI) = 7%) or ferrous sulfate heptahydrate (0.0025 g, C(Fe) = 7%). 2+ (5 mg / L) then reacted with Cu(II)-BHA. Experimental results showed that ZVI bm&ln The addition of ferrous phosphate or ferric phosphate, and sodium dihydrogen phosphate or ferrous sulfate heptahydrate to the system only increased the removal rate of organic reagent ligands by ca. 13.5% and ca. 1.8%, and ca. 10. 5% and ca. 7. 9%, respectively. These results indicate that P-ZVI bm&ln The enhanced ability of activated dissolved oxygen to generate ROS for oxidative degradation of organic ligands depends on the surface ferrous iron (≡Fe) generated by pre-phosphorylation modification with zero-valent iron. 2+ ) Active site.

[0078] Depend on Figure 10 From (a) and (b) in the figure, we can see that in a continuous cyclic reaction, ZVI bm and ZVI bm&ln Organic reagent ligands in Cu(II)-BHA are almost impossible to remove. P-ZVI bm and P-ZVI bm&ln It exhibits good ability to remove Cu(II)-BHA in a cyclic process. During the second cyclic removal reaction, P-ZVI... bm and P-ZVI bm&ln The third cycle of removal reaction degraded ca. 60.1% and 80.0% of the organic ligands, respectively. The fourth cycle degraded ca. 40.0% and 70.1% of the organic ligands, respectively. The fifth cycle degraded ca. 24.9% and 61.1% of the organic ligands, respectively. P-ZVI bm&ln The ability of continuous cyclic reaction to degrade organic ligands in Cu(II)-BHA is significantly improved, and the performance of continuous cyclic removal of total Cu is also improved. The total copper recycling removal rate is maintained above 97.7%, which shows good application potential.

[0079] Depend on Figure 11 From (a) and (b), we can see that using P-ZVI bm&lnThis study treated actual wastewater (mineral processing wastewater containing residual organic reagents and acidic mine wastewater containing heavy metals) from copper mines in East and Southwest China. The initial chemical oxygen demand (COD) concentrations were ca. 213.2 mg / L and 545.2 mg / L, respectively; the initial total organic carbon (TOC) concentrations were ca. 14.5 mg / L and 12.8 mg / L, respectively; and the initial total copper (Cu) concentrations were ca. 16.9 mg / L and 40.1 mg / L, respectively. The batch treatment volume was 100 mL, and P-ZVI was used. bm&ln The dosage was 5 g / L, the batch reaction time was 1 hour, and the reaction was repeated 3 times. In the treatment of actual wastewater from a copper mine in East China, the first two consecutive treatments removed ca. 54.4% and 53.1% of COD, ca. 70.2% and 68.3% of TOC, and ca. 99.1% and 98.4% of total Cu, respectively, with average removal rates of 114.5, 10.1, and 16.7 mg·L⁻¹, respectively. -1 ·h -1 In the treatment results of actual wastewater from a copper mine in Southwest China, the first two consecutive treatments removed ca. 83.3% and 81.8% of COD, ca. 60.2% and 58.7% of TOC, and ca. 99.5% and 98.9% of total Cu, respectively, with average removal rates of 449.9, 7.6, and 39.8 mg·L⁻¹, respectively. -1 ·h -1 The COD and total Cu concentrations in the first two consecutive treatments of the actual mine wastewater both met the People's Republic of China Irrigation Water Quality Standard GB 5084—2021 (COD≤150mg / L, Total Cu≤0.5mg / L) and the Copper, Nickel and Cobalt Industry Pollutant Discharge Standard GB 25467-2010 (COD≤100mg / L, Total Cu≤0.5mg / L), demonstrating strong recycling reactivity and promising practical application prospects.

[0080] In addition, to investigate the changes in ecotoxicity of actual mine wastewater, actual wastewater from copper mines in East and Southwest China was used to cultivate mung bean seeds. The germination rate of mung bean seeds cultivated from untreated copper mine wastewater in East China was 18.8%, which was lower than that obtained by P-ZVI assay. bm&ln The treated wastewater increased the germination rate to 87.5%. The germination rate of mung bean seeds cultured in untreated copper mine wastewater from Southwest China was 6.3%, while the germination rate after P-ZVI treatment was significantly higher. bm&ln The treated wastewater increased the germination rate to 81.3%. These results indicate that P-ZVI... bm&ln The treatment significantly reduced the ecotoxicity of mine wastewater.

[0081] Example 5:

[0082] Phosphorylated micron-sized zero-valent iron (P-ZVI) enhanced by liquid nitrogen cryogenic treatment with a molar ratio of 1%–9% was synthesized using sodium dihydrogen phosphate as a phosphorylation precursor. bm&ln (The only difference from Example 4 is the amount of sodium dihydrogen phosphate used.)

[0083] Example 6:

[0084] P-ZVI synthesized using other phosphorylation precursors (phosphate, sodium monohydrogen phosphate, and sodium phosphate) bm&ln (The only difference from Example 4 is the phosphorylation precursor.)

[0085] The performance of materials in Examples 5 and 6 in removing Cu(II)-BHA after 1 hour of reaction was tested according to the above-described method for testing material properties.

[0086] Figure 12 (a) shows the performance of Example 5 in removing Cu(II)-BHA, finding that a molar ratio of 7% P-ZVI... bm&ln It exhibits optimal performance in BHA degradation and total Cu removal. Figure 12 (b) shows the performance of Cu(II)-BHA removal in Example 6, with results indicating that P-ZVI using sodium dihydrogen phosphate as a precursor... bm&ln It exhibits optimal performance in BHA degradation and total Cu removal.

[0087] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, substitutions, simplifications, or combinations made without departing from the scientific essence and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing phosphorylated micron-sized zero-valent iron enhanced by liquid nitrogen cryogenic treatment, characterized in that, Includes the following steps: Phosphorylated micron-sized zero-valent iron powder is obtained by ball milling a mixture of micron-sized zero-valent iron powder and a phosphorylation precursor using a mechanochemical method. The phosphorylation precursor includes at least one of sodium dihydrogen phosphate, potassium dihydrogen phosphate, phosphoric acid, sodium monohydrogen phosphate, potassium monohydrogen phosphate, sodium phosphate, and potassium phosphate. The zero-valent iron is phosphorylated to form a ferrous phosphate shell. The ball milling speed is 400-800 rpm, and the ball milling time is 1-5 h. The phosphorylated micron-sized zero-valent iron was cryogenically frozen with liquid nitrogen to obtain phosphorylated micron-sized zero-valent iron enhanced by liquid nitrogen cryogenic treatment. The liquid nitrogen cryogenic treatment formed cracks on the surface of the phosphorylated micron-sized zero-valent iron. The molar ratio of the phosphorylated precursor to micron-sized zero-valent iron powder is 0.07:1; the cryogenic freezing is liquid nitrogen immersion for 10-15 minutes.

2. The preparation method according to claim 1, characterized in that, The particle size of the micron-sized zero-valent iron powder is 80~300 μm.

3. The preparation method according to claim 1, characterized in that, The stainless steel grinding balls used in the ball mill have diameters of 0.4~0.6 cm and 1.0~1.2 cm.

4. Phosphorylated micron-sized zero-valent iron enhanced by liquid nitrogen freezing treatment prepared by the preparation method according to any one of claims 1-3.

5. The application of the liquid nitrogen cryogenic treatment-enhanced phosphorylated micronized zero-valent iron of claim 4 in the treatment of actual mine wastewater containing organic reagents and heavy metals, wherein the application is to simultaneously remove heavy metal ions from the wastewater and degrade organic reagents.

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