High-spin sulfur-water iron ore adsorbent material for fixed bed adsorption, preparation method and fixed bed adsorption equipment

Abstract

This application belongs to the technical field of wastewater treatment equipment, and particularly relates to high-spin-state sulfur-hydrothermic ore adsorbent materials for fixed beds, their preparation methods, and fixed-bed adsorption equipment. The high-spin-state sulfur-hydrothermic ore adsorbent material provided in this application, during its preparation process, induces significant Jahn-Teller distortion of the FeO6 octahedron of hydrothermic ore through the weak-field ligand effect of sulfur, thereby inducing Fe… 3+ The transition to a high-spin state modulates spin polarization and promotes the development of some low-spin Fe states. 3+ The transformation of ions to a high-spin state yields high-spin sulfur-iron ore, which enhances its affinity for phosphates and improves the phosphate adsorption performance of sulfur-iron ore. Filling high-spin sulfur-iron ore into fixed-bed adsorption equipment can effectively reduce the pollution of natural water bodies such as groundwater, rivers, and oceans by wastewater and sewage discharge, and avoid algal blooms and red tides.

Description

Technical Field

[0001] This application belongs to the field of wastewater treatment equipment technology, and particularly relates to high spin-state sulfur-water iron ore adsorption materials for fixed beds, their preparation methods, and fixed bed adsorption equipment. Background Technology

[0002] Phosphorus content in normal natural water bodies is extremely low. Once phosphorus is excessive, it can cause eutrophication, which can easily trigger algal blooms, leading to phenomena such as freshwater algal blooms or red tides in nearshore waters, causing irreversible damage to the ecosystem.

[0003] Fixed-bed adsorption equipment uses a variety of adsorbent materials, including activated carbon, molecular sieves, ion exchange resins, biosorbent materials, and inorganic mineral adsorbent materials. Among inorganic mineral adsorbent materials, iron (hydrogen) oxides such as ferrous sulfate ore play an important role in the treatment of anionic pollutants due to their high abundance on Earth, strong ecological compatibility, and surface modifiability. However, the inherently low adsorption capacity and poor anti-interference ability of iron (hydrogen) oxides seriously hinder their practical application. Although the morphology, pore structure, oxygen vacancy introduction, or heterostructure construction of iron (hydrogen) oxides can be improved by controlling synthesis conditions, such as hydrothermal reaction and hydrogen annealing reduction treatment, to achieve morphology control, pore structure adjustment, oxygen vacancy introduction, or heterostructure construction. Adsorption performance; however, morphological regulation, pore structure adjustment, oxygen vacancy introduction, and heterostructure construction of iron (hydride) oxides only change the external morphology or local structure of iron (hydride) oxides, failing to fundamentally alter their intrinsic properties. Studies have shown that the adsorption performance of iron (hydride) oxides and phosphates essentially depends on the interaction between the Fe3d orbitals and the O2p orbitals carried by the phosphate. Therefore, a deeper understanding of this interaction at the orbital level is key to achieving excellent kinetics and anti-interference properties of iron (hydride) oxides, improving the adsorption performance of fixed-bed adsorption equipment, and removing phosphates. It is necessary to develop a high-performance ferrophosphate adsorption material to improve the performance of fixed-bed adsorption equipment. Summary of the Invention

[0004] In view of this, this application provides a high-spin-state sulfur-water ferroore adsorbent material for fixed beds, a preparation method thereof, and a fixed-bed adsorption device, to solve the technical problem of low adsorption performance of ferroore filled in existing fixed-bed adsorption devices.

[0005] The first aspect of this application provides a method for preparing a high-spin-state sulfur-water iron ore adsorbent for a fixed bed, comprising the following steps:

[0006] The ferrohydrate particles were dispersed in deionized water to obtain a ferrohydrate dispersion.

[0007] Sodium dithionite was dissolved in deionized water to obtain a sodium dithionite solution.

[0008] Under an inert atmosphere, sodium dithionite solution and ferrohydrate dispersion were mixed and sealed in a constant-temperature shaker to induce Taylor distortion of the FeO6 octahedrons in ferrohydrate, thus obtaining a high-spin-state sulfur-ferrohydrate adsorbent material for fixed beds.

[0009] Preferably, the oscillation time in the constant temperature shaker is 24~72h, the shaker speed is 50~240r / min, and the temperature is 20~30℃.

[0010] Preferably, the molar ratio of sulfur in the sodium dithionite solution to iron in the ferrophosphate dispersion is 1:0.1~1.0.

[0011] Preferably, the concentration of the ferrohydrate dispersion is 0.01~1 mol / L;

[0012] The concentration of the sodium dithionite solution is 0.05~5 mol / L.

[0013] Preferably, the inert atmosphere is at least one of nitrogen, argon, and helium.

[0014] Preferably, the preparation process of the ferrohydrate particles includes: adding an alkaline solution dropwise to an iron salt solution, controlling the pH to 7.0~8.0 for co-precipitation, and obtaining ferrohydrate particles.

[0015] Preferably, the alkaline solution is selected from at least one of sodium hydroxide, potassium hydroxide, and calcium hydroxide;

[0016] The iron salt solution is selected from at least one of ferric chloride, ferric nitrate, ferric sulfate, and their hydrates.

[0017] Preferably, the concentration of the iron salt solution is 0.2~2 mol / L; the volume is 100~500mL;

[0018] The concentration of the alkaline solution is 0.02~0.25mol / L, the volume is 1L~10L, and the dropping rate is 1~10 mL / min.

[0019] The second aspect of this application provides a high-spin-state sulfur-water iron ore adsorbent material for fixed beds, which is prepared by the preparation method described in the first aspect.

[0020] The third aspect of this application provides a fixed-bed adsorption device, including an inlet unit, a fixed-bed reactor, and an outlet unit; the fixed-bed reactor is filled with a high-spin-state sulfur-water iron ore adsorbent material for fixed beds prepared by the preparation method described in the first aspect.

[0021] The fourth aspect of this application provides the application of the high-spin-state sulfur-water iron ore adsorbent material for fixed beds prepared by the preparation method described in the first aspect in the field of wastewater treatment.

[0022] Compared with the prior art, the method for preparing a high-spin-state sulfur-water iron ore adsorbent material for fixed beds provided in this application has at least the following beneficial effects:

[0023] 1. Characterization tests of structure and performance as performed in Experiment Example 1 and their accompanying documentation. Figure 2-7 It can be seen that the preparation method provided in this application successfully prepared high-spin sulfur-water iron ore, and the total effective magnetic moment (μ) of high-spin sulfur-water iron ore is [missing value]. eff The value is 4.327 μB, and the high-spin state Fe is... 3+ The ion content is approximately 73.1%, significantly higher than that of ordinary ferrohydrate; this indicates that the preparation method provided in this application induces a significant Jahn-Teller distortion of the FeO6 octahedron in ferrohydrate through the weak-field ligand effect of sulfur, thereby inducing Fe... 3+ The transition to a high-spin state.

[0024] 2. Adsorption performance tests and their attachments as described in Experiment Example 2 Figure 8-11 It can be seen that the high-spin sulfur-water iron ore prepared by the preparation method provided in this application has higher adsorption kinetics, adsorption capacity and adsorption rate than water iron ore.

[0025] 3. Adsorption performance tests and their attachments, as shown in Experiment Example 2. Figure 12-13 It can be seen that the high-spin sulfur-water iron ore prepared by the preparation method provided in this application has good adsorption and purification performance for wastewater; after being filled into a fixed bed adsorption device, it has a high removal rate of phosphate in wastewater, which helps the wastewater discharge meet the national sewage discharge standards and effectively reduces pollution to natural water bodies such as groundwater, rivers and oceans. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of a fixed-bed adsorption device provided in Embodiment 4 of this application; the reference numerals include: constant flow pump 1, water inlet pipe 2, fixed-bed reactor glass column 3, water outlet pipe 4, quartz stone 5, high spin state sulfur-water iron ore adsorption material 6, and quartz stone 7.

[0028] Figure 2 X-ray diffraction (XRD) patterns of ferrohydrite and high-spin ferrohydrite provided in Example 1 of this application;

[0029] Figure 3 Raman spectra of ferrohydrite and high-spin state ferrohydrite provided in Example 1 of this application;

[0030] Figure 4 The region electron diffraction (SAED) pattern of high-spin state sulfur-water iron ore provided in Example 1 of this application;

[0031] Figure 5 A high-resolution transmission electron microscope (HRTEM) image of high-spin state sulfur-water iron ore provided in Example 1 of this application;

[0032] Figure 6 The graph shows the reciprocal of the magnetic susceptibility of ferroalloy as a function of temperature, as provided in Embodiment 1 of this application.

[0033] Figure 7 The graph shows the reciprocal of the magnetic susceptibility of the high-spin-state sulfur-water iron ore provided in Embodiment 1 of this application as a function of temperature.

[0034] Figure 8 The graph shows the adsorption kinetics test results of ferrohydrite and high-spin-state sulfur-ferrohydrite provided in Example 1 of this application;

[0035] Figure 9 The graph shows the isothermal adsorption test results of ferrohydrate and high-spin sulfur-ferrohydrate provided in Example 1 of this application.

[0036] Figure 10 The graph shows the test results of the selective adsorption capacity of high-spin-state sulfur-water iron ore provided in Example 1 of this application;

[0037] Figure 11 The graph shows the test results of the phosphorus desorption capacity of high-spin sulfur-water iron ore provided in Example 1 of this application;

[0038] Figure 12 The figure shows the treatment results of high-spin-state sulfur-water iron ore on phosphate, chemical oxygen demand and total nitrogen in wastewater provided in Example 1 of this application;

[0039] Figure 13 The diagram shows the results of phosphate treatment in wastewater using the fixed-bed adsorption device provided in Embodiment 4 of this application. Detailed Implementation

[0040] This application provides a high-spin-state sulfur-water ferroore adsorbent material for fixed beds, a preparation method thereof, and a fixed-bed adsorption device, to solve the technical problem of low adsorption performance of ferroore filled in existing fixed-bed adsorption devices.

[0041] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0042] Currently, the main approaches to iron (hydrogen) oxide adsorbents such as ferrihydrite used in fixed-bed adsorption equipment are morphology control, pore structure adjustment, oxygen vacancy introduction, or heterostructure construction, but there is a lack of modification to their intrinsic properties to improve the performance of fixed-bed adsorption equipment. This application improves the preparation process of ferrihydrite adsorbents and provides a method for preparing high-spin-state ferrihydrite adsorbents for fixed beds. The preparation method involves dispersing ferrihydrite prepared by co-precipitation into oxygen-free deionized water to prepare a ferrihydrite dispersion, and simultaneously dissolving sodium dithionite into oxygen-free deionized water to prepare a sodium dithionite solution. Next, under an inert atmosphere such as nitrogen, the sodium dithionite solution and the ferrihydrite dispersion are mixed and sealed in a constant-temperature shaker to induce Taylor distortion of the FeO6 octahedrons of ferrihydrite, thereby obtaining the high-spin-state ferrihydrite adsorbent.

[0043] The adsorption performance of ferrohydrate and phosphate essentially depends on the interaction between the Fe3d orbitals and the O2p orbitals carried by the phosphate. Spin polarization modulation of ferrohydrate can induce electrons in the t... 2g orbit (d) xy d yz and d xz ) and e g orbit (d) z 2 and d xy 2 The redistribution of electrons among Fe alters the properties of the electron acceptor, when Fe... 3+ From the low-spin state (LS,t) 2g 5 e.g. 0 ) transforms into a high-spin state (HS,t) 2g 3 e g 2 At that time, the low energy t 2g Electrons in the orbit will jump to e g The orbital, this electronic reconfiguration will produce a dual effect, firstly, the vacant t 2g The orbital can act as a strong Lewis acid site to capture the lone pair of electrons of phosphate, which is beneficial for its bonding with the PO σ orbital. On the other hand, e gIncreased electron density in orbitals can enhance charge transfer at the metal-ligand interface through polarization, indirectly stabilizing coordination complexes. In this application, by subjecting ferrohydrate to a sulfidation reaction with sodium dithionite, the weak-field ligand effect of sulfur is utilized to induce a significant Jahn-Teller distortion in the FeO6 octahedron of ferrohydrate, thereby inducing low-spin FeO6 in the ferrohydrate. 3+ The transition to a high-spin state involves spin polarization modulation, which can control Fe... 3+ The ions are adjusted to 73.1% in a high-spin state. The high-spin state of sulfide-ferrous ore enhances its affinity for phosphate. As an adsorption material in fixed-bed adsorption equipment, it has the advantages of fast adsorption rate, high removal rate, and strong selectivity. It exhibits excellent performance in actual wastewater and has broad application prospects for recovering phosphorus from water bodies and realizing resource reuse. At the same time, the synthesis process of sulfide-ferrous ore and sodium dithionite in this application also has the advantages of simple process, easy operation, and high yield. It overcomes the shortcomings of the low adsorption performance of phosphate by currently prepared sulfide-ferrous ore and improves the performance of fixed-bed adsorption equipment.

[0044] The high-spin-state sulfur-water iron ore adsorbent material for fixed beds provided in this application will be specifically described below with reference to embodiments and experimental examples.

[0045] Example 1

[0046] This embodiment provides a method for preparing a high-spin-state sulfur-hydrothermic ore adsorbent material for a fixed bed. The preparation method includes the steps of preparing hydrothermic ore, preparing a hydrothermic ore dispersion, preparing a sodium dithionite solution, and inducing Taylor distortion.

[0047] The steps for preparing ferrohydrate include:

[0048] Prepare 200 mL of 1 mol / L Fe(NO3)3·9H2O solution and 1.6 L of 0.04 mol / L NaOH solution at a molar ratio of 1:3.2. Add the NaOH solution dropwise to the Fe(NO3)3·9H2O solution at a uniform rate of 5 mL / min, maintaining the pH at 7.0–8.0. Stir at room temperature for 6 h. Purify the resulting precipitate to obtain ferrohydrate particles (Fe...). 10 O 14 (OH)2).

[0049] The steps for preparing a ferrous ore dispersion include:

[0050] The obtained 0.015 mol of ferrohydrate was dispersed in 500 mL of oxygen-free deionized water and purged with nitrogen for 30 min to form a ferrohydrate dispersion with a concentration of 0.03 mol / L.

[0051] The steps for preparing a sodium dithionite solution include:

[0052] Dissolve 0.25 mol of sodium dithionite (Na2S2O4) in 250 mL of deionized water to form a sodium dithionite solution with a concentration of 1 mol / L.

[0053] The steps to induce Taylor distortion include:

[0054] Sodium dithionite solution was added to a ferrohydrate dispersion at a sulfur / iron molar ratio of 1:0.3 under a nitrogen atmosphere. The mixture was sealed and placed in a constant-temperature shaker at 25°C for 48 hours to induce Taylor distortion. The precipitate was then post-treated by repeatedly washing it with deionized water, centrifuging, and then drying it in a freeze-drying oven for 24 hours. The dried product was then ground in a mortar until it was a smooth powder, yielding a high-spin sulfur-ferrohydrate adsorbent. During the shaking process in the constant-temperature shaker, the weak-field ligand effect of sulfur induced significant Taylor distortion in the FeO6 octahedrons of ferrohydrate, promoting the low-spin Fe... 3+ The transition to a high-spin state yielded a high-spin sulfur-water iron ore adsorbent material.

[0055] Example 2

[0056] This embodiment provides a method for preparing a high-spin-state sulfur-hydrothermic ore adsorbent material for a fixed bed. The preparation method includes the steps of preparing hydrothermic ore, preparing a hydrothermic ore dispersion, preparing a sodium dithionite solution, and inducing Taylor distortion.

[0057] The steps for preparing ferrohydrate include:

[0058] Prepare 400 mL of 0.5 mol / L Fe(NO3)3·9H2O solution and 3.2 L of 0.02 mol / L NaOH solution at a molar ratio of 1:3.2. Add the NaOH solution dropwise to the Fe(NO3)3·9H2O solution at a uniform rate of 5 mL / min, maintaining the pH at 7.0–8.0. Stir at room temperature for 12 h. Purify the resulting precipitate to obtain ferrohydrate particles (Fe...). 10 O 14 (OH)2).

[0059] The steps for preparing a ferrous ore dispersion include:

[0060] The obtained 0.01 mol ferrohydrate was dispersed in 500 mL of oxygen-free deionized water and purged with nitrogen for 30 min to form a ferrohydrate dispersion with a concentration of 0.02 mol / L.

[0061] The steps for preparing a sodium dithionite solution include:

[0062] Dissolve 0.25 mol of sodium dithionite (Na2S2O4) in 250 mL of deionized water to form a sodium dithionite solution with a concentration of 1 mol / L.

[0063] The steps to induce Taylor distortion include:

[0064] Sodium dithionite solution was added to a ferrohydrate dispersion under a nitrogen atmosphere at a sulfur / iron molar ratio of 1:0.2. The mixture was sealed and placed in a constant-temperature shaker at 25°C for 48 hours to induce Taylor distortion. The precipitate was then post-treated by repeatedly washing it with deionized water, centrifuging it, and then drying it in a freeze dryer for 24 hours. The dried product was then ground in a mortar until it was powdery and free of particles, thus obtaining a high-spin sulfur-ferrohydrate adsorbent material.

[0065] Example 3

[0066] This embodiment provides a method for preparing a high-spin-state sulfur-hydrothermic ore adsorbent material for a fixed bed. The preparation method includes the steps of preparing hydrothermic ore, preparing a hydrothermic ore dispersion, preparing a sodium dithionite solution, and inducing Taylor distortion.

[0067] The steps for preparing ferrohydrate include:

[0068] Prepare 300 mL of 2 mol / L Fe(NO3)3·9H2O solution and 19.2 L of 0.1 mol / L NaOH solution at a molar ratio of 1:3.2. Add the NaOH solution dropwise to the Fe(NO3)3·9H2O solution at a uniform rate of 10 mL / min, maintaining the pH at 7.0–8.0. Stir at room temperature for 36 h. Purify the resulting precipitate to obtain ferrohydrate particles (Fe...). 10 O 14 (OH)2).

[0069] The steps for preparing a ferrous ore dispersion include:

[0070] The obtained 0.04 mol of ferrohydrate was dispersed in 500 mL of oxygen-free deionized water and purged with nitrogen for 30 min to form a ferrohydrate dispersion with a concentration of 0.08 mol / L.

[0071] The steps for preparing a sodium dithionite solution include:

[0072] Dissolve 0.5 mol of sodium dithionite (Na2S2O4) in 500 mL of deionized water to form a sodium dithionite solution with a concentration of 1 mol / L.

[0073] The steps to induce Taylor distortion include:

[0074] Sodium dithionite solution was added to a ferrohydrate dispersion under a nitrogen atmosphere at a sulfur / iron molar ratio of 1:0.4. The mixture was sealed and placed in a constant-temperature shaker at 25°C for 48 hours to induce Taylor distortion. The precipitate was then post-treated by repeatedly washing it with deionized water, centrifuging it, and then drying it in a freeze dryer for 24 hours. The dried product was then ground in a mortar until it was powdery and free of particles, thus obtaining a high-spin sulfur-ferrohydrate adsorbent material.

[0075] Example 4

[0076] This embodiment 4 provides a fixed-bed adsorption device, the structural schematic diagram of which is shown below. Figure 1 As shown, it includes a constant flow pump, an inlet pipe, a fixed-bed reactor glass column, and an outlet pipe; wherein, the fixed-bed reactor glass column has an inner diameter of 10mm and a height of 200mm; the interior is sequentially filled with quartz, high-spin-state sulfur-water iron ore adsorbent material, and quartz, with the high-spin-state sulfur-water iron ore adsorbent material loading of approximately 10g.

[0077] Experimental Example 1

[0078] This experimental example characterizes the structure and properties of the ferrohydrate and high-spin-state sulfur-ferrohydrate adsorbent materials provided in Example 1.

[0079] Among them, the X-ray diffraction of ferrohydrate and high-spin ferrohydrate provided in Example 1 is as follows: Figure 2 As shown, from Figure 2 It can be seen that, compared with ferrohydrite, high-spin ferrohydrite exhibits new diffraction peaks at 21.2°, 26.3°, 33.3°, 36.7°, 40.3°, and 53.4°, belonging to the FeS(111)\(020)\(121)\(202)\(122)\(231) crystal planes (JCPDS NO.76-0964, labeled as...). ); and Raman spectroscopy such as Figure 3 As shown, from Figure 3 It can be seen that, compared with ferrohydrite, the characteristic peak of Fe-O species in high-spin state ferrohydrite (287 cm⁻¹) is significantly higher. -1 / 379 cm -1 The shift and broadening of the electrons towards higher wavenumbers reveals a strong electronic coupling between S and ferrohydrite in high-spin ferrohydrite. This coupling leads to a decrease in Fe-O bond energy and an increase in Fe-O bond length, inducing the Jahn-Teller distortion of the FeO6 octahedron in ferrohydrite. Simultaneously, from... Figure 4The region electron diffraction (SAED) pattern of high-spin sulfide-ferrohydrite shown indicates that the SAED diffraction rings of sulfide-ferrohydrite correspond to the (110) / (220) / (115) crystal planes of sulfide-ferrohydrite and the (111) / (040) crystal planes of Fe-S, confirming that a portion of the sulfide-ferrohydrite has been transformed into FeS; and from Figure 5 The high-resolution transmission electron microscopy (HRTEM) of the high-spin state sulfhydrite shows that it is composed of interconnected nanoparticles. The lattice fringes of the sulfhydrite (FeS(111) crystal plane, 3.79 Å; Fe5O7(OH)(110) crystal plane, 2.80 Å) are clearly visible. However, the cell volume of Fe5O7(OH)(110) is about 8.1% larger than that of sulfhydrite (Fe5O7(OH)(110) crystal plane, 2.59 Å). The weak-field ligand effect of sulfur induces the Jahn-Teller distortion of the FeO6 octahedron in sulfhydrite, which induces the Fe... 3+ The transition to a high-spin state.

[0080] The magnetic susceptibility of the hydromercured ore and the high-spin-state sulfidium-hydromercured ore provided in Example 1 was further characterized, and the results are as follows: Figure 6-7 As shown; from Figure 6-7 It can be seen that the total effective magnetic moment (μ) of the ferrohydride is eff The value is 3.209 μB, corresponding to Fe 3+ The ions exist in a 54.2% high-spin state and a +45.8% low-spin state, while the total effective magnetic moment (μ) of the high-spin state sulfur-water iron ore is... eff The value is 4.327 μB, corresponding to Fe 3+ The ions are in a 73.1% high-spin state and a +26.9% low-spin state; this indicates that the high-spin state of the sulfide-hydrothermal ore provided in this application induces significant Taylor distortion of the FeO6 octahedron in the hydrothermal ore through the weak-field ligand effect of sulfur, thus promoting Fe... 3+ The transition to a high-spin state alters the intrinsic properties of ferrohydride, causing electrons to move from a low-energy t state. 2g Electrons in the orbit will jump to e g Track, empty t 2g The orbital acts as a strong Lewis acid site, trapping the lone pair of electrons from the phosphate group, while the e g Increased electron density in the orbitals can enhance charge transfer at the metal-ligand interface through polarization, indirectly stabilizing the coordination complex, enhancing the interaction between the Fe3d orbitals of ferrophosphate and the O2p orbitals carried by phosphate, and improving adsorption performance.

[0081] Experiment Example 2

[0082] This experiment tests the adsorption performance of the ferrohydrate and high-spin-state sulfur-ferrohydrate adsorption materials provided in Example 1 and the fixed-bed adsorption equipment provided in Example 4.

[0083] The performance testing of adsorption kinetics of adsorption materials includes:

[0084] Prepare a phosphate (KH2PO4) solution with an initial concentration of 5 mg P / L. Take 200 mL of each solution into an Erlenmeyer flask and add 200 mg of the ferrohydrate or high-spin ferrohydrate adsorbent material provided in Example 1. Stir the solution at 25 °C, pH = 6, and 180 r / min. Extract the mixed solution at different time intervals until the process is complete.

[0085] And from Figure 8 The test results show that the ferrohydrate provided in Example 1 requires 40 minutes to reach 90% equilibrium adsorption capacity, while the high-spin sulfur-ferrohydrate adsorbent material provided in Example 1 can reach 99% equilibrium adsorption capacity for phosphate within 3 minutes. The adsorption rate h0 of the high-spin sulfur-ferrohydrate provided in Example 1 is as high as 32.35 mg P / g min, which is more than 146 times that of ferrohydrate.

[0086] The performance testing of isothermal adsorption of adsorption materials includes:

[0087] Prepare phosphate (KH₂PO₄) solutions with initial concentrations of 5–120 mg P / L. Take 20 mL of each solution and add 20 mg of either ferrohydrate or high-spin ferrohydrate adsorbent material provided in Example 1 to each solution. Incubate the solutions at 25 °C and 180 rpm in a constant temperature shaking incubator for 24 h. After the reaction, take a small amount of the solution and detect the phosphate concentration C in the solution using ultraviolet fluorescence. e The equilibrium adsorption capacity Q of the ferrohydrate or high-spin sulfur-ferrohydrate adsorbent material under different initial concentrations was calculated. e The formula for calculating the equilibrium adsorption capacity is shown in Equation I:

[0088] Formula I;

[0089] In Formula I, C0 is the initial phosphate solution concentration (mg / L), C e Q represents the phosphate solution concentration (mg / L) after the adsorption process reaches equilibrium. e When the adsorption reaches equilibrium, the mass of phosphate adsorbed per unit mass of the ferrohydrate or high-spin ferrohydrate adsorbent material provided in Example 1 is V, which is the volume of the phosphate solution (L).

[0090] from Figure 9The performance test results show that as the initial phosphate solution concentration increases from 5 mg P / L to 120 mg P / L, the mass of phosphate adsorbed per unit mass of the ferrohydrate or high-spin ferrohydrate adsorbent material provided in Example 1 also increases, and gradually tends to level off. However, when adsorption reaches equilibrium, the mass of phosphate adsorbed per unit mass of ferrohydrate is much lower than that adsorbed per unit mass of the high-spin ferrohydrate adsorbent material. The high-spin ferrohydrate adsorbent material, at an initial phosphate solution concentration of 120 mg P / L, has a lower Q... e It has a concentration of 81.2 mg P / g, which is 4.14 times that of ferrohydrate.

[0091] The testing of the selective adsorption performance of adsorbent materials includes:

[0092] A phosphate solution control group and a coexisting anion solution group were prepared. A 5 mg / L phosphate solution prepared with KH₂PO₄ served as the control group (CK). A coexisting anion solution group was prepared using KH₂PO₄ and NaNO₃. In the coexisting anion solution group (5 mg / L)... The concentration is 5 mg / L. The concentration was 5 mg / L, and in the coexisting anion solution group (25 mg / L) The concentration was 25 mg / L. The concentration was 25 mg / L, and in the coexisting anion solution group (125 mg / L) The concentration was 125 mg / L. The concentration was 125 mg / L; simultaneously, referring to the coexisting anion solution group prepared using KH2PO4 and NaNO3, coexisting anion solution groups were prepared using KH2PO4 and Na2SO4, NaCl, NaF, or NaHCO3 respectively; the coexisting anion solution group contained simultaneously and , , , or ;

[0093] Weigh 500 mg of the high-spin state sulfur-water iron ore adsorbent provided in Example 1, and add it to 100 mL of coexisting anion solution. Place the solutions in a constant temperature shaker at 25°C and 180 r / min for 24 h. After testing the phosphate solution concentration after adsorption, calculate the removal rate using the formula: Removal rate = (Concentration before adsorption - Concentration after adsorption) / Concentration before adsorption × 100%. The test results are as follows: Figure 10 As shown;

[0094] from Figure 10 The performance test results shown indicate that... With 5 mg / L , , , or When anions coexist, or with 25 mg / L , , , or When anions coexist, high-spin sulfur-water iron ore has no effect on phosphate removal rate, but its effect is greater than that of high concentration (125 mg / L). , , , or Even when anions coexist, it does not significantly affect the removal rate of phosphate by high-spin sulfur-water iron ore.

[0095] The testing of the phosphorus desorption capacity of adsorbent materials includes:

[0096] Weigh 500 mg of the high-spin state sulfur-water iron ore adsorbent provided in Example 1 and add it to 500 mL of KH2PO4 solution containing 10 mg P / L. Place the solution in a constant temperature shaker at 25°C and a rotation speed of 180 r / min for 24 h to obtain a saturated adsorbent. Wash the saturated adsorbent five times with deionized water and add it to a mixed solution containing 2 mol NaOH and 1 mol Na2CO3. Shake at room temperature for 12 h. Take the supernatant to determine the phosphorus concentration and calculate the phosphorus desorption ratio. Rinse the regenerated adsorbent several times with deionized water, dry it, and use it as the adsorbent for the next round. Repeat this process 5 times.

[0097] from Figure 11 The performance test results show that the high-spin sulfur-water iron ore adsorbent provided in Example 1 has a good phosphorus desorption effect in 5 cycles of adsorption, with a desorption rate of up to 85%. The adsorption capacity of the adsorbent shows a slight decrease, which may be due to the formation of irreversible complexes during adsorption, which occupy the active sites. However, the regeneration adsorption performance is good. The high phosphorus desorption capacity and regeneration adsorption performance are beneficial to the recovery of non-renewable phosphorus resources and the regeneration and utilization of high-spin sulfur-water iron ore adsorbent.

[0098] The performance testing of the adsorption material's actual wastewater treatment capacity includes:

[0099] After collecting wastewater and pretreating it by removing suspended particles, the concentrations of COD, phosphate, and ammonia nitrogen before adsorption were tested.

[0100] Weigh 500 mg of the high-spin sulfur-water iron ore adsorbent material provided in Example 1 and add it to 500 mL of collected wastewater. Place it in a constant temperature shaker and shake for 24 h at 25°C and 180 r / min. Test the concentrations of COD, phosphate, and ammonia nitrogen after adsorption, and calculate the removal rate by using the formula: Removal rate = (Concentration before adsorption - Concentration after adsorption) / Concentration before adsorption × 100%.

[0101] By controlling the constant flow pump in the fixed bed adsorption device provided in Example 4, the phosphate-containing wastewater was adjusted to flow from the inlet pipe into the glass column of the fixed bed reactor at a flow rate of 1 mL / min for adsorption reaction. The residual water sample after treatment was collected every 10 minutes to test the phosphate effluent concentration in the residual water sample.

[0102] from Figure 12 The performance test results show that the high-spin sulfur-water iron ore adsorbent material provided in Example 1 has a good removal rate of phosphate in actual wastewater, approaching 100%, and also reduces the concentration of chemical oxygen demand (COD) and total nitrogen (mainly ammonium nitrogen) in the wastewater, with removal rates of 72.9% and 12.6% for COD and ammonium nitrogen, respectively; while from Figure 13 The performance test results show that after filling the fixed bed adsorption device with 10g of the high spin state sulfur-water iron ore adsorption material provided in Example 1, it still maintains a good phosphate removal rate when treating 450 bed volumes, and the treatment limit is about 620 bed volumes of wastewater.

[0103] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. The application of high-spin-state sulfur-water iron ore adsorbent material for fixed beds in the field of wastewater treatment for phosphate adsorption, characterized in that, The preparation method of the high-spin-state sulfur-water iron ore adsorbent material for fixed beds includes the following steps: The ferrohydrate particles were dispersed in deionized water to obtain a ferrohydrate dispersion. Sodium dithionite was dissolved in deionized water to obtain a sodium dithionite solution. Under an inert atmosphere, sodium dithionite solution and ferrohydrate dispersion were mixed and sealed in a constant temperature shaker to induce Taylor distortion of the FeO6 octahedron of ferrohydrate, thus obtaining a high-spin sulfur-ferrohydrate adsorbent material for fixed beds. The molar ratio of sulfur in the sodium dithionite solution to iron in the ferrophosphate dispersion is 1:0.1~1.

0.

2. The application according to claim 1, characterized in that, The oscillation time in the constant temperature shaker is 24~72h, the shaker speed is 50~240r / min, and the temperature is 20~30℃.

3. The application according to claim 1, characterized in that, The concentration of the ferrohydrate dispersion is 0.01~1 mol / L; the concentration of the sodium dithionite solution is 0.05~5 mol / L.

4. The application according to claim 1, characterized in that, The inert atmosphere is at least one of nitrogen, argon, and helium.

5. The application according to claim 1, characterized in that, The preparation process of the ferrohydrate particles includes: adding an alkaline solution dropwise to an iron salt solution, controlling the pH to 7.0~8.0 for co-precipitation, and obtaining ferrohydrate particles.

6. The application according to claim 5, characterized in that, The alkali is selected from at least one of sodium hydroxide, potassium hydroxide, and calcium hydroxide; the iron salt is selected from at least one of ferric chloride, ferric nitrate, ferric sulfate, and their respective hydrates.

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