A low-toxicity conversion and structural locking method of trivalent antimony in groundwater

Abstract

This invention discloses a method for the low-toxicity transformation and structural locking of trivalent antimony in groundwater. The method includes: adding a suspension of ferrous sulfide nanomaterials stabilized with sodium carboxymethyl cellulose to water containing trivalent antimony to obtain a composite solution; and, under room temperature and aerobic conditions, utilizing the reactive oxygen species mediated during the CMC-FeS oxidation transformation to drive the efficient oxidation of Sb(III) to low-toxicity pentavalent antimony. Simultaneously, iron (hydroxyl) oxides generated in situ during the material phase transition, through structural doping, instantly and firmly lock the oxidation product Sb(V) within the mineral lattice. This invention overcomes the limitations of traditional iron-based materials that rely solely on a single adsorption or reduction process, constructing a synergistic mechanism of "interfacial oxidation-mineral evolution-structural locking" under neutral conditions, achieving green and long-term stable treatment of antimony pollution, and possessing significant engineering application prospects.

Description

Technical Field

[0001] This invention belongs to the field of environmental pollution control and remediation technology, specifically relating to a method for the low-toxicity transformation and structural locking of trivalent antimony in groundwater. Background Technology

[0002] Antimony (Sb), a toxic metal, is causing increasing pollution problems globally. Mining, smelting, and various industrial activities lead to the continuous accumulation of antimony in soil and groundwater, posing a serious threat to the ecological environment and human health. In natural water bodies, antimony mainly exists in the forms of trivalent antimony (Sb(III)) and pentavalent antimony (Sb(V)), with Sb(III) being ten times more toxic than Sb(V). Currently, the remediation technology for Sb(III) in groundwater mainly focuses on the adsorption process under anaerobic conditions. These methods only achieve the transfer of Sb(III) from the aqueous phase to the solid phase, without changing the valence state of the highly toxic Sb(III), and there is a risk of re-release under fluctuating environmental conditions, failing to achieve true detoxification and transformation. Therefore, oxidizing Sb(III) to the less toxic Sb(V) has become a key detoxification pathway in antimony pollution remediation.

[0003] Existing oxidation remediation technologies often rely on the addition of external chemical oxidants (such as potassium permanganate and ozone), which are not only costly but also prone to introducing additional chemicals that can lead to secondary pollution. Furthermore, advanced oxidation technologies based on the Fenton reaction have extremely stringent pH requirements, severely limiting the practical engineering application of traditional oxidation technologies in groundwater.

[0004] Ferrous sulfide, a typical iron-based mineral, has long been defined in traditional remediation studies as a passivating agent for heavy metals and a reducing agent for inorganic pollutants (such as Cr(VI)) and organic pollutants, primarily limited to anaerobic remediation scenarios. Furthermore, FeS particles are highly prone to aggregation, exhibiting poor mass transfer and migration capabilities in porous groundwater media, making efficient in-situ remediation of groundwater difficult.

[0005] Therefore, developing a green remediation technology that can achieve synergistic effects of efficient Sb(III) oxidation and in-situ long-term stabilization has become a key scientific and engineering problem that urgently needs to be solved in the field of environmental remediation. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method for the low-toxicity transformation and structural locking of trivalent antimony in groundwater.

[0007] The objective of this invention is achieved through the following technical solution.

[0008] A method for low-toxicity conversion and structural locking of trivalent antimony in groundwater includes: adding a suspension of sodium carboxymethyl cellulose stabilized ferrous sulfide nanomaterials (CMC-FeS) to a water body containing trivalent antimony to obtain a composite solution; and conducting an aerobic reaction at room temperature to allow the sodium carboxymethyl cellulose stabilized ferrous sulfide nanomaterials (CMC-FeS) to adsorb trivalent antimony (Sb(III)) and oxidize trivalent antimony (Sb(III)) to pentavalent antimony (Sb(V)), thereby achieving low-toxicity conversion and structural locking of trivalent antimony. Before the aerobic reaction, the concentration of sodium carboxymethyl cellulose stabilized ferrous sulfide nanomaterials (CMC-FeS) in the composite solution is 28.5~31.5 mg / L.

[0009] In the above technical solution, before the oscillation reaction, the concentration of trivalent antimony in the composite solution is 9.6~10.5 mg / L.

[0010] In the above technical solution, the concentration of sodium carboxymethyl cellulose stabilized ferrous sulfide nanomaterials (CMC-FeS) in the suspension is 490~510 mg / L.

[0011] In the above technical solution, the pH value of the composite liquid is 4.5-8.5, preferably 6.8-7.2.

[0012] In the above technical solution, the oscillation reaction is carried out under dark conditions.

[0013] In the above technical solution, when the reaction is shaken for 4 hours under room temperature, oxygen, and dark conditions, sodium carboxymethyl cellulose stabilizes ferrous sulfide nanomaterials (CMC-FeS) and adsorbs 74% of trivalent antimony (Sb(III)).

[0014] In the above technical solution, when the reaction is carried out under oscillation conditions at room temperature, in the presence of oxygen, and in the dark for 4 hours, the oxidation rate of trivalent antimony (Sb(III)) to pentavalent antimony (Sb(V)) by sodium carboxymethyl cellulose stabilized ferrous sulfide nanomaterials (CMC-FeS) is 72.1%.

[0015] In the above technical solution, the method for preparing the suspension includes the following steps:

[0016] Step 1: Under a nitrogen or inert gas atmosphere, mix the soluble ferrous salt solution and the sodium carboxymethyl cellulose aqueous solution until homogeneous to obtain a first mixture. The ratio of soluble ferrous salt in the soluble ferrous salt solution to sodium carboxymethyl cellulose in the sodium carboxymethyl cellulose aqueous solution is (0.465~0.485):0.086 by mass.

[0017] In step 1, the soluble ferrous salt is ferrous chloride tetrahydrate (FeCl2·4H2O).

[0018] In step 1, the method for obtaining a soluble ferrous salt solution includes: mixing soluble ferrous salt and first water until homogeneous to obtain a soluble ferrous salt solution, wherein the mass fraction of soluble ferrous salt and the volume fraction of first water are (0.465~0.485):200, the mass fraction is in g and the volume fraction is in mL.

[0019] In step 1, the method for obtaining an aqueous solution of sodium carboxymethyl cellulose includes: mixing sodium carboxymethyl cellulose and second water until homogeneous to obtain an aqueous solution of sodium carboxymethyl cellulose, wherein the content of sodium carboxymethyl cellulose in the aqueous solution is 0.1 wt%.

[0020] Step 2: Under a nitrogen or inert gas atmosphere, mix the sulfide aqueous solution and all of the first mixture from Step 1 until homogeneous, seal, and let stand in an anaerobic environment at room temperature for at least 24 hours to obtain the suspension. The ratio of the soluble ferrous salt in the first mixture to the sulfide in the sulfide aqueous solution is (0.465~0.485):(0.57~0.59) by mass.

[0021] In step 2, the sulfide is sodium sulfide nonahydrate (Na2S·9H2O).

[0022] In step 2, the method for obtaining the sulfide aqueous solution includes: mixing the sulfide and the third water until homogeneous to obtain the sulfide aqueous solution, wherein the mass fraction of the sulfide and the volume fraction of the third water are (0.57~0.59):100, the mass fraction is in g and the volume fraction is in mL.

[0023] In the above technical solution, the first water, the second water, and the third water are all anaerobic deionized water.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1. This invention utilizes sodium carboxymethyl cellulose to stabilize the reactive oxygen species generated by ferrous sulfide nanomaterials (CMC-FeS) under aerobic conditions. This efficiently oxidizes highly toxic trivalent antimony (Sb(III)) into less toxic pentavalent antimony (Sb(V)), while simultaneously and firmly locking the pentavalent antimony within the newly formed iron (hydroxy) oxide lattice. This achieves deep detoxification and long-term stabilization of Sb(III). This method for the low-toxicity conversion and structural locking of trivalent antimony in groundwater is green, rapid, and efficient.

[0026] 2. The CMC-FeS particles used in this invention have small particle size, large specific surface area, are environmentally friendly, have excellent hydrodynamic stability and soil transferability, and can be delivered to the core area of ​​groundwater pollution plume through in-situ injection and other methods, making them suitable for in-situ remediation of groundwater environments.

[0027] 3. The CMC-FeS provided by this invention not only has good adsorption performance for trivalent antimony under aerobic and neutral conditions, but also continuously generates active oxygen species (such as superoxide radicals, hydroxyl radicals, etc.) through surface-mediated oxidation reactions, thereby achieving a synergistic effect of chemical oxidation and structural locking, breaking through the limitations of traditional materials that rely solely on adsorption or a single oxidation process. Attached Figure Description

[0028] Figure 1 X-ray diffraction patterns of CMC-FeS and FeS;

[0029] Figure 2 The trend graph of trivalent antimony concentration corresponding to the sample taken at hour t of the reaction suspension under aerobic conditions in Test Example 1 is used as the test solution.

[0030] Figure 3 The trend graph of Sb(III) content and Sb(V) content in the liquid phase under aerobic conditions in Test Example 1;

[0031] Figure 4 The trend graph of Sb(III) content and Sb(V) content in the solid phase under aerobic conditions in Test Example 1;

[0032] Figure 5 The trend graph shows the total trivalent antimony content and the total pentavalent antimony content under aerobic conditions in Test Example 1;

[0033] Figure 6 The trend graph shows the total trivalent antimony content and total pentavalent antimony content under anaerobic conditions in Test Example 1;

[0034] Figure 7 The removal rates of trivalent antimony by CMC-FeS under anaerobic and aerobic conditions;

[0035] Figure 8 For the Mössbauer spectrum of oxidation in Example 2, taken at 4 hours.

[0036] Figure 9 The images show the morphology of oxidized CMC-FeS, where (a) is a transmission electron microscope (TEM) image and (b) is a high-resolution transmission electron microscope (HRTEM) image.

[0037] Figure 10 The images show the morphology of oxidized Sb-CMC-FeS, where (a) is a transmission electron microscope (TEM) image and (b) is a high-resolution transmission electron microscope (HRTEM) image.

[0038] Figure 11 XRD patterns of CMC-FeS, Sb-CMC-FeS, oxidized CMC-FeS, and oxidized Sb-CMC-FeS;

[0039] Figure 12 Fourier transform infrared (FTIR) spectra of CMC-FeS, Sb-CMC-FeS, oxidized CMC-FeS, and oxidized Sb-CMC-FeS;

[0040] Figure 13 The percentages of Sb(III) and Sb(V) in the surface adsorbed state and lattice doped state in the solid phase after 4 h of oxidation are given.

[0041] Figure 14 This is a trend chart of dissolved oxygen.

[0042] Figure 15 This is a trend graph of redox potential;

[0043] Figure 16 The results of test example 5 are shown, where (a) is the oxidation rate of the experimental group and the control group, and (b) is the electron paramagnetic resonance spectrum.

[0044] Figure 17 The results for test example 6 are shown, where (a) is a trend graph of •OH concentration and (b) is a graph of •O2 concentration. - Concentration trend graph;

[0045] Figure 18 The results for test example 7 are shown, where (a) is the oxidation rate of experiment 1 at the 4th hour and (b) is the oxidation rate of experiment 2 at the 4th hour.

[0046] Figure 19 The images show the appearance of the suspension of sodium carboxymethyl cellulose-stabilized ferrous sulfide nanomaterials (CMC-FeS) prepared in Example 1 and the mixture of ferrous sulfide materials prepared in Comparative Example 1. (a) shows the appearance of the suspension of sodium carboxymethyl cellulose-stabilized ferrous sulfide nanomaterials (CMC-FeS) after standing; (b) shows the appearance of the mixture of ferrous sulfide materials after standing; (c) shows the appearance of the suspension of sodium carboxymethyl cellulose-stabilized ferrous sulfide nanomaterials (CMC-FeS) after shaking; and (d) shows the appearance of the mixture of ferrous sulfide materials after shaking. Detailed Implementation

[0047] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0048] The sources of the pharmaceuticals involved in the following examples, comparative examples, and test cases are as follows:

[0049] Ferrous chloride tetrahydrate (FeCl2·4H2O), sodium sulfide nonahydrate (Na2S·9H2O), coumarin (COU, 98%), 7-hydroxycoumarin (7-hCOU), nitrotetrazole blue chloride (NBT), dimethyl sulfoxide (DMSO, ≥99.9%), catalase (CAT, 3500 units / mg), 1,4-benzoquinone (BQ), L-histidine (L-His), and tert-butanol (TBA) were purchased from Shanghai Maclean Biochemical Technology Co., Ltd., China.

[0050] Antimony trioxide (Sb2O3) and sodium carboxymethyl cellulose (abbreviated as CMC-Na or CMC, MW = 90000) were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0051] The instrument models and manufacturers used in the following test examples are as follows:

[0052] Dissolved oxygen meter and redox potential meter: Hach Corporation, USA;

[0053] X-ray diffraction analyzer (XRD): Bruker GmbH, Germany;

[0054] Fourier Transform Infrared Spectrometer (FTIR): Thermo Fisher Scientific, Inc., USA;

[0055] High-resolution transmission electron microscope (HRTEM, model: JEM-2100F): JEOL Ltd.

[0056] Mössbauer spectrometer (model: WSS-10): WissEL GmbH, Germany;

[0057] UV-Vis spectrophotometer (model UV-2700): Shimadzu, Japan;

[0058] Atomic fluorescence spectrometer (model: AFS-9900): Beijing Kechuang Haiguang Instrument Co., Ltd.;

[0059] Fluorescence spectrophotometer (model: FluoroMax-4): Houlibo Precision Instruments (Beijing) Co., Ltd.

[0060] In the examples, comparative examples, and test examples, anaerobic deionized water was obtained by removing dissolved oxygen from deionized water through nitrogen purging (bubbling) for 30 min. Anaerobic deionized water was used to ensure that the phase purity of CMC-FeS and FeS and the surface active sites were not prematurely consumed or destroyed by dissolved oxygen.

[0061] In the test case, antimony trioxide (Sb2O3) and anaerobic deionized water were mixed to obtain water to be treated with a concentration of 100 mg / L of trivalent antimony (Sb(III)) and a pH value of 7.

[0062] In the test example, "aerobic and dark" means: creating dark conditions by wrapping the body and mouth of the reaction flask with aluminum foil, and evenly poking holes in the mouth of the flask to allow the liquid in the reaction flask to communicate with the air, so that oxygen can enter and cause an oxidation reaction.

[0063] In the test case, anaerobic and dark means: wrapping the body and mouth of the reaction flask with aluminum foil to create dark conditions, tightening the cap and sealing it with sealing film to maintain an anaerobic environment.

[0064] Oxidation rate = (Total pentavalent antimony content (T)) Sb(Ⅴ) () / initial Sb(III) content) * 100%.

[0065] The removal rate of Sb(III) = ((initial Sb(III) content - Sb(III) content in the liquid phase at the t-th hour of shaking) / initial Sb(III) content) * 100%.

[0066] Example 1

[0067] A method for preparing a suspension containing sodium carboxymethyl cellulose stabilized ferrous sulfide nanomaterials (CMC-FeS) includes the following steps:

[0068] Step 1: At room temperature, nitrogen gas is continuously introduced into the reagent bottle (perborate glass bottle) to remove air. While maintaining the nitrogen gas supply, the soluble ferrous salt solution and the sodium carboxymethyl cellulose aqueous solution are added to the reagent bottle. Nitrogen gas is then continuously purged (in a bubbling manner) for 5 minutes until the mixture is homogeneous, resulting in the first mixture. The mass ratio of soluble ferrous salt in the soluble ferrous salt solution to sodium carboxymethyl cellulose in the sodium carboxymethyl cellulose aqueous solution is 0.4752:0.086.

[0069] The method for obtaining a soluble ferrous salt solution includes: mixing a soluble ferrous salt (ferrous chloride tetrahydrate) and a first water under nitrogen purging (bubbling) for 3 min until homogeneous, to obtain a soluble ferrous salt solution (FeCl2 solution). The mass fraction of the soluble ferrous salt to the volume fraction of the first water is 0.4752:200, where the mass fraction is in g and the volume fraction is in mL.

[0070] The method for obtaining an aqueous solution of sodium carboxymethyl cellulose includes: mixing sodium carboxymethyl cellulose and second water, stirring at 180 rpm for 12 h at room temperature until homogeneous, to obtain an aqueous solution of sodium carboxymethyl cellulose, wherein the content of sodium carboxymethyl cellulose in the aqueous solution is 0.1 wt%, and the aqueous solution of sodium carboxymethyl cellulose is purged with nitrogen (bubbling form) for 10 min before use;

[0071] Step 2: Under nitrogen purging (bubbling), add the sulfide aqueous solution dropwise to all the first mixture from Step 1. Tightly cap the reagent bottle and seal it with sealing film. Shake the bottle up and down for 1 minute until homogeneous. Let it stand for 24 hours in an anaerobic chamber (nitrogen atmosphere) at room temperature to obtain a suspension containing sodium carboxymethyl cellulose stabilized ferrous sulfide nanomaterials (CMC-FeS) (CMC-FeS is black nanoparticles). The concentration of sodium carboxymethyl cellulose stabilized ferrous sulfide nanomaterials (CMC-FeS) in the suspension is 500 mg / L. The ratio of soluble ferrous salt to sulfide in the sulfide aqueous solution, by mass fraction, is 0.4752:0.5741. The method for obtaining the sulfide aqueous solution includes: mixing the sulfide (sodium sulfide nonahydrate) and the third water under nitrogen purging (bubbling) for 3 minutes... The solution was heated until homogeneous to obtain an aqueous solution of sulfide (Na2S aqueous solution). The ratio of the mass fraction of sulfide to the volume fraction of the third water was 0.5741:100. The mass fraction is expressed in g and the volume fraction is expressed in mL.

[0072] The first, second, and third waters are all anaerobic deionized water.

[0073] Comparative Example 1

[0074] A method for preparing a mixture containing ferrous sulfide material includes: adding the aqueous solution of sulfide prepared in Example 1 dropwise to the soluble ferrous salt solution prepared in Example 1 under nitrogen purging (bubbling), then adding the fourth water (anaerobic deionized water), sealing the reagent bottle with a sealing film after tightening the cap, shaking the reagent bottle up and down for 1 minute until the mixture is uniform, and letting it stand for 24 hours in an anaerobic chamber at room temperature (the anaerobic chamber is under a nitrogen atmosphere) to obtain a mixture containing ferrous sulfide material (FeS is black granules). The concentration of ferrous sulfide material (FeS) in the mixture is 500 mg / L. The ratio of soluble ferrous salt in the soluble ferrous salt solution to sulfide in the aqueous sulfide solution is 0.4752:0.5741 by mass, and the ratio of aqueous sulfide solution to fourth water is 10:12 by volume.

[0075] Under static conditions, the appearances of the suspension of sodium carboxymethyl cellulose-stabilized ferrous sulfide nanomaterials (CMC-FeS) prepared in Example 1 and the mixture of ferrous sulfide nanomaterials prepared in Comparative Example 1 are as follows: Figure 19 (a) and Figure 19 As shown in (b). Under shaken conditions, the appearances of the suspension of sodium carboxymethyl cellulose sodium-stabilized ferrous sulfide nanomaterials (CMC-FeS) prepared in Example 1 and the mixture of ferrous sulfide nanomaterials prepared in Comparative Example 1 are as follows: Figure 19 (c) and Figure 19As shown in (d). By Figure 19 It can be seen that the FeS in the mixture containing ferrous sulfide material settles significantly under static conditions and shows obvious stratification under shaking conditions, while the suspension of sodium carboxymethyl cellulose stabilized ferrous sulfide nanomaterial (CMC-FeS) shows a uniform dispersion under both static and shaking conditions.

[0076] The hydrodynamic diameter and Zeta potential of FeS in the suspension of sodium carboxymethyl cellulose-stabilized ferrous sulfide nanomaterials (CMC-FeS) prepared in Example 1 and the mixture of ferrous sulfide-containing materials prepared in Comparative Example 1 were determined using a nanoparticle size and potential analyzer (Nano ZSE, Malvern Instruments Ltd., UK). The results showed that the hydrodynamic diameter of CMC-FeS was 254 nm (mean) and the Zeta potential was -38.1 mV, indicating excellent colloidal stability. The hydrodynamic diameter of FeS was 3215 nm (mean) and the Zeta potential was -25.0 mV, indicating poor colloidal stability, making it almost impossible to migrate in groundwater. This invention, through CMC modification, fundamentally inhibits FeS aggregation and improves colloidal dispersion stability, enabling CMC-FeS to possess transferability and effective migration capabilities in groundwater environments.

[0077] Preparation of CMC-FeS: Nitrogen gas was introduced into the reaction flask from the bottom. A suspension of sodium carboxymethyl cellulose-stabilized ferrous sulfide nanomaterials (CMC-FeS) prepared in Example 1 and anaerobic deionized water were added to the reaction flask to obtain a CMC-FeS dispersion with a pH of 7. After the CMC-FeS dispersion was prepared, the nitrogen gas was stopped from being introduced into the reaction flask. The concentration of CMC-FeS in the CMC-FeS dispersion was 30 mg / L. Under anaerobic and dark conditions, the CMC-FeS dispersion was placed in a shaker and shaken at 180 rpm for 4 h. It was then filtered using a 25 nm mixed cellulose ester filter membrane. The filtered solid was freeze-dried in a freeze dryer (Scientz-10 N type) at -35℃ for 48 h to obtain CMC-FeS.

[0078] Preparation of FeS: This is basically the same as the preparation of CMC-FeS, except that the "suspension of sodium carboxymethyl cellulose-stabilized ferrous sulfide nanomaterials (CMC-FeS) prepared in Example 1" is replaced with "a mixture of ferrous sulfide materials prepared in Comparative Example 1".

[0079] The prepared CMC-FeS and FeS were subjected to XRD tests, and the results are as follows: Figure 1 As shown. By Figure 1It can be seen that the diffraction peaks of CMC-FeS are wider than those of FeS and tend to be amorphous, indicating that CMC plays a role in nanoscale size control and inhibits the aggregation of FeS particles.

[0080] Test Example 1

[0081] Test 1: Nitrogen gas was introduced into the reaction flask from the bottom. A suspension of sodium carboxymethyl cellulose sodium-stabilized ferrous sulfide nanomaterials (CMC-FeS) prepared in Example 1 and water to be treated were added to the reaction flask to obtain a composite solution with a pH of 7. After the composite solution was prepared, the nitrogen gas was stopped from being introduced into the reaction flask. The concentration of CMC-FeS in the composite solution was 30 mg / L, and the concentration of trivalent antimony in the composite solution was 10 mg / L. The volume of the composite solution in this test was 50 mL (therefore, the initial Sb(III) content was 4.106 μmol). Under aerobic and dark conditions, the composite solution was placed on a shaker and shaken at 180 rpm to obtain a reaction suspension. 0.5 mL of the reaction suspension was sampled at hour t of shaking as a sample. The concentration of trivalent antimony and the concentration of antimony in the sample were measured, and then the concentration of pentavalent antimony in the sample at that sampling time was obtained. t hour = one of 0h, 0.5h, 1h, 2h, 3h, 4h, 6h, 8h, and 12h. Multiple parallel samples were set up for each sample.

[0082] Total trivalent antimony content: The sample was directly used as the detection solution and the "Trivalent Antimony Concentration Detection Method" was followed to obtain the trivalent antimony concentration. The trivalent antimony concentration was multiplied by 50 mL to obtain the total trivalent antimony content.

[0083] Total antimony content: The sample was used directly as the detection solution according to the "Antimony Concentration Detection Method" to obtain the antimony concentration. The antimony concentration was multiplied by 50 mL to obtain the total antimony content.

[0084] Total pentavalent antimony content: The difference between the antimony concentration and the trivalent antimony concentration is calculated as the pentavalent antimony concentration. Multiply the pentavalent antimony concentration by 50 mL to obtain the total pentavalent antimony content.

[0085] Sb(III) content in liquid phase: The sample was filtered through a 25 nm mixed cellulose ester filter membrane and then used as the detection solution according to the "Trivalent Antimony Concentration Detection Method". The trivalent antimony concentration was obtained as the trivalent antimony concentration in liquid phase, which was recorded as the liquid phase Sb(III) concentration. The liquid phase Sb(III) concentration was multiplied by 50 mL to obtain the Sb(III) content in liquid phase.

[0086] Sb content in liquid phase: The sample was filtered through a 25 nm mixed cellulose ester filter membrane. The filtered solution was used as the detection solution and processed according to the "antimony concentration detection method". The antimony concentration was obtained as the antimony concentration in the liquid phase, which was recorded as the liquid phase Sb concentration. The liquid phase Sb concentration was multiplied by 50 mL to obtain the Sb content in the liquid phase.

[0087] Sb(V) content in liquid phase: The difference between the Sb content in liquid phase and the Sb(III) content in liquid phase is calculated as the Sb(V) content in liquid phase.

[0088] Sb(III) content in the solid phase: The difference between the total trivalent antimony content and the Sb(III) content in the liquid phase is taken as the Sb(III) content in the solid phase.

[0089] Sb content in the solid phase: The difference between the total antimony content and the Sb content in the liquid phase is taken as the Sb content in the solid phase.

[0090] Sb(V) content in the solid phase: The difference between the total pentavalent antimony content and the Sb(V) content in the liquid phase is taken as the Sb(V) content in the solid phase.

[0091] Method for detecting trivalent antimony concentration: Add 4.5 mL of hydrochloric acid (HCl concentration of 6 M) to the test solution (approximately 0.5 mL) to acidify and provide an acidic detection environment. Immediately add 100 μL of methanol to terminate the oxidation reaction of trivalent antimony and prevent further oxidation of Sb(III), resulting in solution A. Take 0.8 mL of solution A and add 2 mL of sodium citrate aqueous solution (sodium citrate aqueous solution is obtained by mixing 0.8 g of sodium citrate and 40 mL of deionized water, and then use 2 mL of it) to mask Sb(V). Add another 0.8 mL of hydrochloric acid (HCl concentration of 6 M), and add deionized water to make up to 8 mL to obtain the first test solution. Use an atomic fluorescence spectrometer to determine the concentration of trivalent antimony in the first test solution.

[0092] Antimony concentration detection method (the pentavalent antimony formed by oxidation needs to be reduced to trivalent antimony before measurement): Add 4.5 mL of hydrochloric acid (HCl concentration of 6 M in hydrochloric acid) to 0.5 mL of test solution, and immediately add 100 μL of methanol to terminate the oxidation reaction of trivalent antimony, to obtain solution A. Add 1.6 mL of mixed solution (dissolve 2 g of thiourea in 30 mL of deionized water, then add 2 g of ascorbic acid, and add deionized water to make up to 40 mL to obtain mixed solution, and then take 1.6 mL of it for use) to reduce all Sb(V) to Sb(III), add 0.8 mL of hydrochloric acid (HCl concentration of 6 M in hydrochloric acid), and add deionized water to make up to 8 mL to obtain the second test solution. Use an atomic fluorescence spectrometer to measure the Sb(III) concentration in the second test solution and record it as the antimony concentration.

[0093] When the sample is used directly as the detection solution, the concentration of trivalent antimony in the sample at different sampling times ( Figure 2 The results of “total Sb(III)” are as follows Figure 2 As shown. By Figure 2It can be seen that the oxidation of Sb(III) by CMC-FeS basically reached equilibrium at 4 h, and the total Sb(III) value decreased from 82.1 μM to 22.9 μM. CMC-FeS can effectively promote the adsorption and oxidation of Sb(III).

[0094] The Sb(III) content in the liquid phase at t hours = 0h, 0.5h, 1h, 2h, 3h, and 4h ( Figure 3 The content of Sb(III)aq in the liquid phase and the content of Sb(V) in the liquid phase ( Figure 3 In the Chinese, “Sb(V)aq” is as follows: Figure 3 As shown, the Sb(III) content in the solid phase ( Figure 4 The content of "Sb(III)s" in the solid phase and the content of Sb(V) in the solid phase ( Figure 4 In the phrase “Sb(V)s”, the meaning is as follows: Figure 4 As shown, the total trivalent antimony content ( Figure 5 China T Sb(III) ) and total pentavalent antimony content ( Figure 5 China T Sb(V) )like Figure 5 As shown.

[0095] Depend on Figure 3 , Figure 4 and Figure 5 It can be seen that at h0, the Sb(III) content in the liquid phase was 4.106 μmol, and the Sb(V) content in the liquid phase was 0 μmol. The Sb(III) content in the solid phase at h0 was also 0 μmol. The Sb(III) content in the liquid phase decreased from h0 to h0.5, while the Sb(III) content in the solid phase increased from h0 to h0.5, indicating that Sb(III) in the liquid phase was rapidly captured and adsorbed by CMC-FeS. At h0.5, 63.5% (calculated from (4.106 - 1.5) μmol / 4.106 μmol) of Sb(III) in the liquid phase was adsorbed on the CMC-FeS surface. Furthermore, at h0.5, the formation of Sb(V) was detected in the solid phase. This indicates that the adsorbed Sb(III) did not remain in its initial form, but rather underwent rapid oxidation on the CMC-FeS surface, transforming into Sb(V). At 4 h, 74% (calculated from (4.106-1.07) μmol / 4.106 μmol) of Sb(III) in the liquid phase was adsorbed. The degree of Sb(III) oxidation increased over time, with the total pentavalent antimony content at 0.5 h, 1 h, and 4 h being 0.903 μmol, 1.70 μmol, and 2.96 μmol, respectively. The oxidation rate increased from 22.0% at 0.5 h and 41.4% at 1 h to 72.1% at 4 h.

[0096] Test 2: Under anaerobic and dark conditions, the composite solution (same as the composite solution in Test 1) was placed on a shaker and shaken at 180 rpm to obtain a reaction suspension. At hour t of shaking, 0.5 mL of the reaction suspension was taken as a sample, and the total trivalent antimony content was obtained according to the method in Test 1. Figure 6 China T Sb(III) ) and total pentavalent antimony content ( Figure 6 China T Sb(V) ). t hours = 0h, 0.5h, 1h, 2h, 3h, and 4h. From Figure 6 It can be seen that the formation of Sb(V) under anaerobic conditions is negligible, indicating that CMC-FeS has no oxidizing effect on Sb(III) under anaerobic conditions.

[0097] The removal rates of Sb(III) by CMC-FeS under aerobic conditions were obtained based on Test 1, and the removal rates of Sb(III) by CMC-FeS under anaerobic conditions were obtained based on Test 2. The removal rates at 0h, 0.5h, 1h, 2h, 3h, and 4h are shown below. Figure 7 As shown. By Figure 7 It can be seen that the removal efficiency of CMC-FeS for Sb(III) differs under aerobic and anaerobic conditions. Under aerobic conditions, the removal rate of Sb(III) reaches as high as 74% at 4 h, and the oxidation rate is 72.1% at 4 h, indicating that the reaction of CMC-FeS with Sb(III) under aerobic conditions is mainly surface-mediated oxidation, following a pathway of adsorption followed by oxidation. CMC-FeS oxidizes the more toxic Sb(III) into the less toxic Sb(V), thus achieving efficient removal and detoxification. In contrast, under anaerobic conditions, the removal rate of Sb(III) at 4 h is only 53.2%, which, combined with... Figure 6 Under anaerobic conditions, the formation of Sb(V) is negligible. Sb(III) in the liquid phase is transferred to the solid phase only through adsorption by CMC-FeS, and its valence state remains unchanged. The removal rate of Sb(III) under aerobic conditions is significantly higher than that under anaerobic conditions, indicating that the presence of dissolved oxygen significantly enhances the removal efficiency of Sb(III) by CMC-FeS.

[0098] Test Example 2

[0099] Nitrogen gas was introduced into the reaction flask from the bottom. A suspension of sodium carboxymethyl cellulose-stabilized ferrous sulfide nanomaterials (CMC-FeS) prepared in Example 1 and anaerobic deionized water were added to the flask to obtain a CMC-FeS dispersion with a pH of 7. After the CMC-FeS dispersion was prepared, nitrogen gas introduction into the reaction flask was stopped. The concentration of CMC-FeS in the CMC-FeS dispersion was 30 mg / L. Under aerobic and dark conditions, the CMC-FeS dispersion was shaken at 180 rpm for 4 hours. The mixture was then filtered through a 25 nm mixed cellulose ester filter membrane. The filtered solid was freeze-dried at -35°C in a Scientz-10 N-type freeze dryer for 48 hours to obtain oxidized CMC-FeS powder. Iron species in the oxidized CMC-FeS powder were analyzed using a Mössbauer spectrometer (model: WSS-10). Transmission mode was used for data acquisition. 57 A Co / Rh gamma-ray source (SEE Co., USA) (Doppler velocity range -5 to 5 mm / s) was used, and the test temperature was 290 K. [The following data was obtained...] Figure 8 The Mössbauer spectrum is shown.

[0100] like Figure 8 As shown, FeS was completely converted to the oxidized form after 4 h of oxidation, and the formation of the final oxidation product, paramagnetic dual-state fibrous ferrite, was confirmed at 290 K.

[0101] Test Example 3

[0102] Nitrogen gas was introduced into the bottom of the reaction flask. A suspension of sodium carboxymethyl cellulose-stabilized ferrous sulfide nanomaterials (CMC-FeS) prepared in Example 1 and anaerobic deionized water were added to the reaction flask to obtain a CMC-FeS dispersion with a pH of 7. After the CMC-FeS dispersion was prepared, the nitrogen gas was stopped from being introduced into the reaction flask. The concentration of CMC-FeS in the CMC-FeS dispersion was 30 mg / L. Under aerobic and dark conditions, the CMC-FeS dispersion was placed in a shaker and shaken at 180 rpm for 4 hours. It was then filtered using a 25 nm mixed cellulose ester filter membrane. The filtered solid was freeze-dried to obtain oxidized CMC-FeS.

[0103] Nitrogen gas was introduced into the bottom of the reaction flask. A suspension of sodium carboxymethyl cellulose-stabilized ferrous sulfide nanomaterials (CMC-FeS) prepared in Example 1 and water to be treated were added to the reaction flask to obtain a composite solution with a pH of 7. After the composite solution was prepared, the nitrogen gas was stopped from being introduced into the reaction flask. The concentration of CMC-FeS in the composite solution was 30 mg / L, and the concentration of trivalent antimony in the composite solution was 10 mg / L. Under aerobic and dark conditions, the composite solution was placed in a shaker and shaken at 180 rpm for 4 hours. It was then filtered using a 25 nm mixed cellulose ester filter membrane. The filtered solid was freeze-dried to obtain oxidized Sb-CMC-FeS.

[0104] Nitrogen gas was introduced into the bottom of the reaction flask. A suspension of sodium carboxymethyl cellulose sodium stabilized ferrous sulfide nanomaterials (CMC-FeS) prepared in Example 1 and anaerobic deionized water were added to the reaction flask to obtain a CMC-FeS dispersion with a pH of 7. After the CMC-FeS dispersion was prepared, the nitrogen gas was stopped from being introduced into the reaction flask. The concentration of CMC-FeS in the CMC-FeS dispersion was 30 mg / L. Under anaerobic and dark conditions, the CMC-FeS dispersion was placed in a shaker and shaken at 180 rpm for 4 hours. It was then filtered using a 25 nm mixed cellulose ester filter membrane. The filtered solid was freeze-dried to obtain CMC-FeS.

[0105] Nitrogen gas was introduced into the bottom of the reaction flask. A suspension of sodium carboxymethyl cellulose-stabilized ferrous sulfide nanomaterials (CMC-FeS) prepared in Example 1 and water to be treated were added to the reaction flask to obtain a composite solution with a pH of 7. After the composite solution was prepared, the nitrogen gas was stopped from being introduced into the reaction flask. The concentration of CMC-FeS in the composite solution was 30 mg / L, and the concentration of trivalent antimony in the composite solution was 10 mg / L. Under anaerobic and dark conditions, the composite solution was placed in a shaker and shaken at 180 rpm for 4 hours. It was then filtered using a 25 nm mixed cellulose ester filter membrane. The filtered solid was freeze-dried to obtain Sb-CMC-FeS.

[0106] In Test Example 3, the freeze-drying process included freeze-drying at -35°C in a freeze dryer (Scientz-10 N type) for 48 h.

[0107] The morphology of oxidized CMC-FeS was characterized to obtain... Figure 9 The transmission electron microscope (TEM) image shown in (a) and Figure 9 The high-resolution transmission electron microscope (HRTEM) image shown in (b) illustrates the morphological characterization of oxidized Sb-CMC-FeS. Figure 10 The transmission electron microscope image shown in (a) and Figure 10 The high-resolution transmission electron microscope image shown in (b) is as follows.

[0108] Depend on Figure 9 and Figure 10 The TEM images of oxidized CMC-FeS show strip-like and plate-like nanostructures. HRTEM images reveal lattice spacings of 0.194 nm, 0.246 nm, and 0.329 nm, corresponding to the (200), (031), and (120) crystal planes of lepidocrocite (γ-FeOOH), respectively. Based on these lattice spacings, it was identified as lepidocrocite (γ-FeOOH). Oxidized Sb-CMC-FeS appears as an irregular aggregate with lattice spacings of 0.246 nm and 0.235 nm, and was also identified as γ-FeOOH based on these spacings. These analyses confirm that FeS oxidation under neutral conditions primarily produces γ-FeOOH, and that antimony incorporation affects the crystallization process and final morphology of lepidocrocite.

[0109] X-ray diffraction was used to analyze the crystal phase structure of CMC-FeS, Sb-CMC-FeS, oxidized CMC-FeS, and oxidized Sb-CMC-FeS, and the results were obtained. Figure 11 The XRD diffraction pattern is shown. Surface functional group analysis of CMC-FeS, Sb-CMC-FeS, oxidized CMC-FeS, and oxidized Sb-CMC-FeS was performed using Fourier transform infrared spectroscopy, yielding... Figure 12 The FTIR spectrum shown.

[0110] like Figure 11 As shown, Sb-CMC-FeS exhibits five new diffraction peaks relative to CMC-FeS, corresponding to Sb₂S₃, indicating a chemical precipitation between CMC-FeS and Sb(III). Oxidized CMC-FeS shows seven distinct peaks corresponding to lepidocrocite (γ-FeOOH), indicating a phase transformation of CMC-FeS to γ-FeOOH. Furthermore, characteristic peaks of S are detected at 23.1°, 25.9°, 27.8°, and 31.5°, confirming the oxidation of FeS to γ-FeOOH and S. For oxidized Sb-CMC-FeS, the characteristic peak of γ-FeOOH is still detectable, but its intensity is weakened. This is because Sb(V) inhibits the formation of lepidocrocite, resulting in goethite (α-FeOOH). Lepidocrocite and goethite are iron (hydroxy) oxides. In the presence of antimony, the crystallinity of oxidized CMC-FeS decreased from 50.4% to 26.5% (the crystallinity of oxidized CMC-FeS is 50.4%, and the crystallinity of oxidized Sb-CMC-FeS is 26.5%). These changes are attributed to the inner spherical complexation of Sb(V) with iron (hydroxy) oxides and the structural incorporation of Sb(V) into the Fe(III) lattice.

[0111] like Figure 12As shown, FTIR analysis of CMC-FeS revealed five characteristic peaks. Similar absorption peaks were observed after Sb(III) adsorption, with slight wavelength shifts in some peaks, and the wavelength at 1037 cm⁻¹ was also observed. -1 CO peak at 1610 cm⁻¹ -1 The intensity of the -COOH peak at the oxidized Sb-CMC-FeS decreases, and these changes are attributed to the surface complexation between CMC-FeS and Sb(III). Oxidized Sb-CMC-FeS is transformed into a complex phase containing ferrihydrite and goethite, and can form stable Fe(III)–O–Sb(V) chemical bonds with Sb(V), thereby achieving stable antimony fixation.

[0112] Phosphate extraction experiments were used to distinguish between surface-adsorbed Sb(III) and Sb(V) states and lattice-doped Sb(III) and Sb(V) states in the solid phase. The extractable portion of phosphate was classified as the surface-adsorbed state, while the non-extractable portion was classified as the lattice-doped state. The phosphate extraction experiment included: nitrogen gas was introduced into the reaction flask from the bottom, and a suspension of sodium carboxymethyl cellulose sodium-stabilized ferrous sulfide nanomaterials (CMC-FeS) prepared in Example 1 and water to be treated were added to the reaction flask to obtain a composite solution with a pH of 7. After the composite solution was prepared, the nitrogen gas was stopped from being introduced into the reaction flask. The concentration of CMC-FeS in the composite solution was 30 mg / L, and the concentration of trivalent antimony in the composite solution was 10 mg / L. The volume of the composite solution in this test was 50 mL (therefore the initial Sb(III) content was 4.106 μmol). Under aerobic and dark conditions, the composite solution was placed on a shaker and shaken at a speed of 180 rpm to obtain a reaction suspension. 0.5 mL, 1 mL and 1 mL samples were taken at the fourth hour of shaking of the reaction suspension as the first sample, the second sample and the third sample, respectively (four portions of the first sample were taken, and one portion each of the second and third samples were taken). Specifically, the total trivalent antimony content of the first sample (0.5 mL) was obtained by following the method for "total trivalent antimony content" in Test Example 1 above; the total antimony content of the second sample was obtained by following the method for "total antimony content" in Test Example 1 above; and the total pentavalent antimony content was calculated by following the method for "total pentavalent antimony content" in Test Example 1 above.

[0113] The Sb(III) content in the liquid phase of the third sample (0.5 mL) was obtained according to the method for "Sb(III) content in the liquid phase" in Test Example 1 above; the Sb content in the liquid phase of the fourth sample (0.5 mL) was obtained according to the method for "Sb content in the liquid phase" in Test Example 1 above; and the Sb(V) content in the liquid phase was calculated according to the method for "Sb(V) content in the liquid phase" in Test Example 1 above. Then, the contents of surface-adsorbed trivalent antimony, surface-adsorbed pentavalent antimony, lattice-doped trivalent antimony, and lattice-doped pentavalent antimony were obtained according to the following operations:

[0114] The second sample (1 mL) was mixed with 5 mL of 1 M NaH2PO4 aqueous solution and mixed at 30 rpm for 16 h in a rotary mixer. Then, 0.5 mL of the mixture was taken as a sample and used directly as the detection solution according to the "Trivalent Antimony Concentration Detection Method" in Test Example 1 above to obtain the trivalent antimony concentration. The trivalent antimony concentration was multiplied by 50 mL to obtain the content of surface adsorbed trivalent antimony.

[0115] The third sample (1 mL) was mixed with 5 mL of 1 M NaH2PO4 aqueous solution and mixed in a rotary mixer at 30 rpm for 16 h. Then, 0.5 mL of the mixture was taken as the final sample and used directly as the detection solution according to the "Antimony Concentration Detection Method" in Test Example 1 above to obtain the antimony concentration. The difference between this antimony concentration and the trivalent antimony concentration of the second sample was calculated as the pentavalent antimony concentration. This pentavalent antimony concentration was multiplied by 50 mL to obtain the content of surface-adsorbed pentavalent antimony.

[0116] Lattice-doped trivalent antimony content = total trivalent antimony content - Sb(III) content in liquid phase - surface adsorbed trivalent antimony content; Lattice-doped pentavalent antimony content = total pentavalent antimony content - Sb(V) content in liquid phase - surface adsorbed pentavalent antimony content.

[0117] Based on the content of trivalent antimony in the lattice-doped state, the content of trivalent antimony in the surface-adsorbed state, the content of pentavalent antimony in the lattice-doped state, and the content of pentavalent antimony in the surface-adsorbed state, calculate the percentage of Sb in different valence states in the lattice-doped state and the surface-adsorbed state, such as... Figure 13 As shown, phosphate extraction experiments were used to distinguish between surface-adsorbed Sb(III) and Sb(V) in the oxidized solid phase and lattice-doped (non-extracted) Sb(III) and Sb(V). The results showed that antimony in the solid phase mainly exists in the form of Sb(V), with Sb(III) accounting for only a very small proportion (5.4%), achieving significant oxidation detoxification. Crucially, Sb(V) in the solid phase mainly exists in the form of structured lattice doping (accounting for 77.9% of the total antimony in the solid phase), while the traditional surface-adsorbed Sb(V) accounts for only 16.7%. This distribution characteristic confirms that during the mineral phase transformation induced by nano-FeS oxidation, Sb(V) enters the framework of newly formed iron (hydroxy) oxides through a structured embedding mechanism. This structural doping fundamentally ensures the long-term stability of the antimony-containing solid phase.

[0118] To assess the leaching toxicity of Sb in oxidized CMC-FeS, the "oxidized Sb-CMC-FeS" from Test Example 3 was subjected to a Toxicity Characteristic Leaching Procedure (TCLP) experiment according to EPA Method 1311. The supernatant from the 18-hour mark of the TCLP experiment was filtered through a 25 nm mixed cellulose ester membrane. The filtered solution was used as the test solution and analyzed according to the "Antimony Concentration Detection Method." The Sb concentration in the filtrate was measured to be 0.029 mg / L. This value was divided by the antimony concentration in the solid phase before the TCLP experiment (3.957 mg / L), yielding a leaching percentage of 99.3%. The TCLP results show that the leached antimony content was significantly reduced by 99.3% after treatment. This confirms that the present invention achieves long-term safe disposal of pollutants by efficiently anchoring antimony in the lattice of the oxidation products.

[0119] Test Example 4

[0120] The trends of dissolved oxygen and redox potential changes in CMC-FeS of Example 1 and FeS of Comparative Example 1 under aerobic conditions were compared.

[0121] Nitrogen gas was introduced into the reaction flask from the bottom. A liquid containing the remediation material (pH 7) was added to the flask as the reaction solution. After the reaction solution was prepared, nitrogen gas introduction was stopped. The concentration of the remediation material in the reaction solution was 30 mg / L. Under aerobic and dark conditions, the reaction solution was placed on a shaker and shaken at 180 rpm. Changes in dissolved oxygen and redox potential were monitored at 0 h, 0.15 h, 0.5 h, 0.66 h, 1 h, 2 h, 3 h, and 4 h of shaking. Dissolved oxygen was measured using a dissolved oxygen meter, and redox potential was measured using a redox potential meter. The liquid containing the remediation material was a suspension of sodium carboxymethyl cellulose-stabilized ferrous sulfide nanomaterials (CMC-FeS) from Example 1 or a mixture of ferrous sulfide materials from Comparative Example 1 (i.e., the remediation material was either CMC-FeS prepared in Example 1 or FeS prepared in Comparative Example 1).

[0122] Figure 14 and Figure 15The changes in dissolved oxygen and redox potential were shown. When CMC-FeS was used as the remediation material, dissolved oxygen rapidly increased from 0 mg / L to ~6.0 mg / L within 1 h, reaching equilibrium at 8.1 mg / L by 4 h. The redox potential increased sharply from approximately -165.0 mV at 0 h to 78.5 mV at 1 h, stabilizing at ~135.0 mV by 4 h. The oxidation process was essentially completed by 4 h, and the main redox active components in the system reached a relatively stable chemical form. This is highly consistent with the oxidation conversion process of trivalent antimony and ferrous sulfide. This demonstrates that CMC modification did not sacrifice the redox activity of FeS, achieving synergistic optimization of dispersion stability and reactivity.

[0123] Test Example 5

[0124] Control group: Following the method described in "Test 1" of Test Example 1, the oxidation rate of CMC-FeS at the 4th hour was obtained and recorded. Figure 16 "Comparison" in (a).

[0125] Experimental group: Basically the same as the control group, the only difference being that "water to be treated" was replaced with "water to be treated containing an active oxygen quencher". The method for obtaining water to be treated containing an active oxygen quencher includes: adding an active oxygen quencher to the water to be treated to obtain water with a pH of 7 containing an active oxygen quencher. The active oxygen quencher is one of tert-butanol (TBA), 1,4-benzoquinone (BQ), L-histidine (L-His), catalase (CAT), and dimethyl sulfoxide (DMSO). Tert-butanol (TBA), 1,4-benzoquinone (BQ), L-histidine (L-His), catalase (CAT), and dimethyl sulfoxide (DMSO) represent hydroxyl radicals (•OH), superoxide radicals (•O⁻), and singlet oxygen, respectively. 1 O2), hydrogen peroxide (H2O2), and Fe(IV) quenchers. When the active oxygen quencher is tert-butanol, the concentration of tert-butanol (TBA) in the water to be treated containing the active oxygen quencher is 340 mM. Figure 16 In (a), “TBA: 340 mM” and 800 mM ( Figure 16 One of the following in (a) "TBA: 800 mM"; when the active oxygen quencher is 1,4-benzoquinone, the concentration of 1,4-benzoquinone (BQ) in the water to be treated containing the active oxygen quencher is 10 mM ( Figure 16 In (a), “BQ: 10 mM” and 20 mM ( Figure 16 One of "BQ: 20 mM" in (a); when the active oxygen quencher is L-histidine, the concentration of L-histidine (L-His) in the water to be treated containing the active oxygen quencher is 10 mM ( Figure 16In (a), “L-His: 10mM” and 20 mM ( Figure 16 One of the following in (a) "L-His: 20 mM"; when the reactive oxygen quencher is catalase, the concentration of catalase (CAT) in the water to be treated containing the reactive oxygen quencher is 35 U / mL. Figure 16 In (a), "CAT: 35UmL" -1 ") and 350 U / mL ( Figure 16 In (a), "CAT: 350 UmL" -1 One of the following; when the active oxygen quencher is dimethyl sulfoxide (DMSO), the concentration of DMSO in the water to be treated containing the active oxygen quencher is 50 mM (…). Figure 16 In (a) "DMSO: 50 mM") and 500 mM ( Figure 16 One of the "DMSO: 500 mM" in (a).

[0126] The oxidation rates of the control group and the experimental group at 4 hours are as follows: Figure 16 As shown in (a), the oxidation rate in the control group was 72.1%. The oxidation rate with the addition of TBA decreased by 9.2%-10.4% compared to 72.1%, and the oxidation rate with the addition of BQ decreased by 54.8%-57.9% compared to 72.1%. These results indicate that •OH and •O2⁻ participate in the oxidative transformation of Sb(III), and •O2⁻ is the dominant active species for Sb(III) oxidation.

[0127] Electron spin resonance spectroscopy (EMXnano) was used to identify hydroxyl radicals (•OH), superoxide radicals (•O₂⁻), and singlet oxygen (•OH). 1 To generate O2, before the test, the CMC-FeS dispersion (the preparation method of the CMC-FeS dispersion is the same as that in test example 2) was allowed to stand for 0.5 hours under aerobic and dark conditions to achieve the rapid stage of active oxygen generation and obtain the reaction solution. Subsequently, 100 μL of the reaction solution was taken and mixed with 10 μL of 5,5-dimethyl-1-pyrrolino-N-oxide (DMPO, purity 97.5%), shaken at 180 rpm for 15 minutes, and •OH was detected. Another 100 μL of the reaction solution was taken and mixed with 10 μL of 5,5-dimethyl-1-pyrrolino-N-oxide (DMPO, purity 97.5%), shaken at 180 rpm for 15 minutes, and •O⁻ was detected. Then, another 100 μL of the reaction solution was taken and mixed with 10 μL of 2,2,6,6-tetramethylpiperidine (TEMP, purity 97%), shaken at 180 rpm for 15 minutes, and •O₂⁻ was detected. 1 O2.

[0128] Test results are as follows Figure 16As shown in (b), Figure 16 The electron paramagnetic resonance spectrum of (b) further confirms the presence of •OH and •O2⁻, indicating that •OH and •O2 - They jointly participate in the oxidation of Sb(III). 1 O2 did not participate in the oxidation of Sb(III).

[0129] To investigate the contribution of different reactive oxygen species (ROS) to Sb(III) oxidation, the concentration of trivalent antimony in the reaction suspension at hour t was measured for the control group, water containing reactive oxygen quenchers corresponding to tert-butanol (TBA), and water containing reactive oxygen quenchers corresponding to 1,4-benzoquinone (BQ). Here, t hour = one of 0 h, 0.5 h, 1 h, 2 h, 3 h, and 4 h. The concentration of trivalent antimony in the reaction suspension at hour 0 was denoted as C0, and the concentrations at hours 0.5 h, 1 h, 2 h, 3 h, and 4 h were denoted as C. t The quasi-first-order dynamic model ln(C0 / C) is adopted. t By performing linear fitting on )=kt, the pseudo-first-order reaction rate constant (k) corresponding to the control group was obtained. 对照 ), the pseudo-first-order reaction rate constant (k) corresponding to the addition of tert-butanol (TBA) 淬灭•OH ) and the pseudo-first-order reaction rate constant (k) corresponding to the addition of 1,4-benzoquinone (BQ). 淬灭•O2 - The pseudo-first-order reaction rate constant is in units of h. -1 The calculation yields k. 对照 k 淬灭•OH and k 淬灭•O2 - The values ​​are 0.3406 h. -1 0.2545 h -1 and 0.0437 h -1 According to k 对照 and k 淬灭•OH Calculate the contribution of •OH to the oxidation of Sb(III) based on k. 对照 and k 淬灭•O2 - Calculation • O2 - Contribution rate to Sb(III) oxidation. The contribution rate (ROS contribution rate) is calculated using the following formula:

[0130] (When calculating the pseudo-first-order reaction rate constant corresponding to the addition of tert-butanol (TBA), k) 淬灭 For k 淬灭•OH When calculating the pseudo-first-order reaction rate constant corresponding to the addition of 1,4-benzoquinone (BQ), k 淬灭 For k 淬灭•O2 - ).

[0131] The contribution of •OH to the oxidation of Sb(III) and •O2 - The contribution rates of Sb(III) oxidation were normalized, and the •OH and •O2 were calculated. - The contribution rates to the oxidation of Sb(III) were 22.5% and 77.5%, respectively, indicating that •O2⁻ plays a major role in the oxidation of Sb(III).

[0132] Test Example 6

[0133] Quantitative detection of •OH (using coumarin as a fluorescent probe, the fluorescence intensity of 7-hydroxycoumarin at 460 nm was measured using a fluorescence spectrophotometer, and the •OH concentration was calculated based on the fluorescence intensity of 7-hydroxycoumarin):

[0134] S1. Establish a standard curve for 7-hydroxycoumarin: Prepare a 1 mmol / L stock solution of 7-hydroxycoumarin by mixing 7-hydroxycoumarin with deionized water. Dilute the stock solution with deionized water to obtain standard solutions of 7-hydroxycoumarin with concentrations of 0.01 μmol / L, 0.05 μmol / L, 0.1 μmol / L, 0.2 μmol / L, 0.5 μmol / L, 1 μmol / L, and 2 μmol / L. Measure the fluorescence intensity of each 7-hydroxycoumarin standard solution using a fluorescence spectrophotometer at an excitation wavelength Ex = 350 nm and an emission wavelength Em = 460 nm. Plot a standard curve with fluorescence intensity on the ordinate and 7-hydroxycoumarin concentration (μM) on the abscissa.

[0135] S2, Nitrogen gas is introduced from the bottom of the reaction flask, and a suspension of sodium carboxymethyl cellulose sodium-stabilized ferrous sulfide nanomaterials (CMC-FeS) prepared in Example 1, anaerobic deionized water, and a 1 mM coumarin aqueous solution (0.0146 g of coumarin powder is dissolved in 100 mL of anaerobic deionized water to obtain a 1 mM coumarin aqueous solution) are added to the reaction flask. (Coumarin reacts with •OH to generate 7-hydroxycoumarin) to obtain a coumarin-CMC-FeS reaction solution with a pH of 7. The concentration of CMC-FeS in the coumarin-CMC-FeS reaction solution is 30 mg / L, and the concentration of coumarin is 0.1 mM. After the coumarin-CMC-FeS reaction solution is prepared, stop the nitrogen gas flow into the reaction flask. Under aerobic and dark conditions, place the coumarin-CMC-FeS reaction solution in a shaker and shake at 180 rpm for 4 hours. Take a sample at hour t (no filtration required) and measure the fluorescence intensity of the coumarin-CMC-FeS reaction solution at hour t. Substitute this fluorescence intensity into the standard curve to obtain the corresponding 7-hydroxycoumarin concentration. t hour = one of 0h, 0.5h, 1h, 2h, 3h, and 4h.

[0136] According to Han, R.; Wang, Z.; Lv, J.; He, K.; Liu, S.; Zhu, Z.; Nriagu, J.; Teng, HH; Zhu, Y.-G.; Li, G. Properties and Reactivity of Iron-OrganicMatter-Arsenic Composites and their Influence on Arsenic Behavior in Microbial Reduction and Oxidation Processes. Environ. Sci. Technol. 2025, 59(13), 6600-6609. DOI: 10.1021 / acs.est.5c00696, the conversion rate of •OH to 7-hydroxycoumarin is 6.1 mol%, i.e., •OH concentration = 7-hydroxycoumarin concentration / 6.1 mol %. Therefore, we obtain... Figure 16 The concentration of •OH during the t-th hour of oscillation in (a).

[0137] Quantitative detection of O2 - (The concentration of superoxide radicals was obtained by detecting the concentration of nitrotetrazole blue chloride (NBT):

[0138] S1, Nitrogen gas is introduced from the bottom of the reaction flask. Nitrotetrazolium chloride (NBT, powder), a suspension of sodium carboxymethyl cellulose sodium-stabilized ferrous sulfide nanomaterials (CMC-FeS) prepared in Example 1, and anaerobic deionized water are added to the reaction flask to obtain an NBT-CMC-FeS reaction solution with a pH of 7. After the NBT-CMC-FeS reaction solution is prepared, the nitrogen gas is stopped from being introduced into the reaction flask. Under aerobic and dark conditions, the NBT-CMC-FeS reaction solution is placed in a shaker and shaken at 180 rpm for 4 hours. A sample is taken at the t-th hour of shaking (no filtration is required) and the absorbance at the t-th hour is measured. The NBT concentration in the NBT-CMC-FeS reaction solution is 180 μM and the CMC-FeS concentration in the NBT-CMC-FeS reaction solution is 30 mg / L.

[0139] S2. First, the absorbance of deionized water at 259 nm was measured using a UV-Vis spectrophotometer for zeroing. Then, the NBT-CMC-FeS reaction solution was placed in a quartz cuvette with a 1 cm optical path. The absorbance of the NBT-CMC-FeS reaction solution at 259 nm before the reaction (denoted as A1) and at 259 nm after t hours of shaking (denoted as A2) were measured. A1 was then substituted into Beer-Lambert law. The initial NBT concentration in the NBT-CMC-FeS reaction solution before the reaction (denoted as Cbefore) was calculated, and A2 was substituted into the Lambert-Beer law. The remaining NBT concentration in the NBT-CMC-FeS reaction solution after the reaction (denoted as Cafter) is calculated. The concentration of NBT consumed during the reaction is obtained by subtracting Cafter from Cbefore. In the Lambert-Beer law, A is the absorbance of NBT at 259 nm, and ε is the molar extinction coefficient of NBT at 259 nm (61000 L / L). -1 mol -1 cm -1C represents the NBT concentration (M) of the NBT-CMC-FeS reaction solution at the measurement time, and L represents the optical path (1 cm) of the quartz cuvette. According to Lin, E.; Kang, Z.; Wu, J.; Huang, R.; Qin, N.; Bao, D. BaTiO3 nanoocubes / cuboids with selectively deposited Ag nanoparticles: Efficient piezocatalytic degradation and mechanism. Appl. Catal., B. 2021, 285, 119823. DOI: 10.1016 / j.apcatb.2020.119823., it can be known that... 1 MNBT corresponds to 4 M•O2 - The reaction amount (i.e., 1 M NBT reacts to remove 4 M •O2) - NBT and •O2 - The reaction stoichiometric ratio is 1:4. Based on this stoichiometric ratio, the concentration of NBT can be calculated. Figure 17 (b) O2 at hour t during oscillation - concentration.

[0140] •OH concentration as Figure 17 As shown in (a), •O2 - Concentration such as Figure 17 As shown in (b), the concentration of •OH generated by CMC-FeS oxidation increased to 1.8 μM at 1 h and reached 2.5 μM at 4 h; •O2 - The concentration rapidly increased to 77.7 μM at 1 h and reached 105.1 μM at 4 h. This further confirms the presence of O2. - It plays a major role in the oxidation of Sb(III).

[0141] Test Example 7

[0142] Experiment 1: It is basically the same as "Test 1" in Test Example 1, except that "the concentration of CMC-FeS in the composite solution is 30 mg / L" is replaced with "the concentration of CMC-FeS in the composite solution is X mg / L", where X = 10, 30, 70 or 100.

[0143] The oxidation rate obtained in Experiment 1 (after shaking for 4 hours) is as follows: Figure 18 As shown in (a). By Figure 18As shown in (a), the oxidation rate is 21.2% when the concentration of CMC-FeS in the composite solution is 10 mg / L, and the oxidation rate reaches 82.9% when the concentration of CMC-FeS in the composite solution is 100 mg / L.

[0144] Experiment 2:

[0145] Group A: Nitrogen gas was introduced into the reaction flask from the bottom. A suspension of sodium carboxymethyl cellulose-stabilized ferrous sulfide nanomaterials (CMC-FeS) prepared in Example 1 and water to be treated were added to the reaction flask to obtain a composite solution (pH 7). The concentration of CMC-FeS in the composite solution was 30 mg / L, and the concentration of trivalent antimony in the composite solution was 10 mg / L.

[0146] Group B: Nitrogen gas was introduced from the bottom of the reaction flask. A suspension of sodium carboxymethyl cellulose-stabilized ferrous sulfide nanomaterials (CMC-FeS) prepared in Example 1 and water to be treated were added to the reaction flask. Hydrochloric acid (HCl concentration of 0.2 mol / L) was added dropwise to obtain a composite solution (pH value of 4.5). The concentration of CMC-FeS in the composite solution was 30 mg / L, and the concentration of trivalent antimony in the composite solution was 10 mg / L.

[0147] Group C: Nitrogen gas was introduced from the bottom of the reaction flask. A suspension of sodium carboxymethyl cellulose sodium-stabilized ferrous sulfide nanomaterials (CMC-FeS) prepared in Example 1 and water to be treated were added to the reaction flask. Sodium hydroxide aqueous solution (the concentration of NaOH in the sodium hydroxide aqueous solution was 0.2 mol / L) was added dropwise to obtain a composite solution (pH value of 8.5). The concentration of CMC-FeS in the composite solution was 30 mg / L, and the concentration of trivalent antimony in the composite solution was 10 mg / L.

[0148] The oxidation rates of groups A, B, and C at 4 h were obtained by referring to the method in "Test 1" of Test Example 1.

[0149] The results are as follows Figure 18 As shown in (b), the oxidation rate was pH-dependent, reaching 51.6% at pH 4.5, peaking at 72.1% at pH 7.0, and decreasing to 65.7% at pH 8.5. The higher oxidation rates observed at pH 7.0 and 8.5 are likely due to the generation of more •O₂⁻ under neutral and alkaline conditions. - It plays a key role in promoting the oxidation of Sb(III). The oxidation rate can be effectively controlled by adjusting the dosage of CMC-FeS and the pH of the system. Under neutral conditions, the oxidation effect of CMC-FeS on Sb(III) is more significant. This result provides an important basis for designing efficient antimony pollution remediation.

[0150] Test Example 8

[0151] Ciprofloxacin (CIP) and anaerobic deionized water were mixed to prepare wastewater with a CIP concentration of 100 mg / L and a pH of 7. The wastewater and the CMC-FeS suspension were mixed evenly in a polyethylene bottle to obtain the test solution. The CIP concentration in the test solution was 10 mg / L and the CMC-FeS concentration was 30 mg / L. Under aerobic and dark conditions, the test solution was placed on a shaker and shaken at 180 rpm for 4 hours.

[0152] The test solution, shaken for 4 h, was filtered through a 25 nm mixed cellulose ester filter membrane to obtain the filtrate. 100 μL of sodium thiosulfate aqueous solution (the concentration of sodium thiosulfate in the sodium thiosulfate aqueous solution was 0.02 M) was added to 1 mL of the filtrate to quench the residual active oxygen species in the reaction system, and the CIP concentration of the liquid phase was analyzed.

[0153] Take 0.8 mL of the test solution after shaking for 4 h, add 0.8 mL of digestion solution and 100 μL of sodium thiosulfate aqueous solution (the concentration of sodium thiosulfate in the sodium thiosulfate aqueous solution is 0.02 M) to quench the residual active oxygen species in the reaction system, and analyze the CIP concentration (total CIP concentration) of the test solution. The digestion solution is prepared by mixing perchloric acid aqueous solution (the concentration of HClO4 in the perchloric acid aqueous solution is 3 M) and methanol at a volume ratio of 1:16 to obtain the digestion solution.

[0154] Method for determining CIP concentration: High performance liquid chromatography (HPLC) was used to analyze CIP concentration. The mobile phase was prepared by mixing acetonitrile and formic acid aqueous solution (the volume fraction of HCOOH in the formic acid aqueous solution was 0.1%) at a volume ratio of 3:7. The flow rate of the mobile phase was 0.3 mL / min, and the detection wavelength was 277 nm.

[0155] CIP removal rate = (initial CIP concentration - CIP concentration in liquid phase at 4h) / initial CIP concentration) * 100%, where the initial CIP concentration is 10 mg / L.

[0156] Degradation rate: (Initial CIP concentration - Total CIP concentration at 4h) / Initial CIP concentration * 100%.

[0157] After 4 hours of reaction under aerobic conditions, CMC-FeS achieved a removal rate of 75.5% for ciprofloxacin and a degradation rate of 63.3%. Of the removed CIP, 83.8% (derived from 63.3% / 75.5%) was degraded, while 16.2% remained adsorbed on oxidation products. This indicates that CMC-FeS has a good removal effect on antibiotics such as ciprofloxacin, effectively destroying the structure of CIP through oxidative degradation. Furthermore, the removal time is short, achieving significant removal and degradation effects in just 4 hours. This demonstrates the advantages of CMC-FeS in high treatment efficiency and rapid reaction, showing good application potential in the treatment of antibiotic-related organic pollutants.

[0158] The inventive point of this invention is reflected in:

[0159] 1. In traditional environmental remediation research, ferrous sulfide (FeS) is typically considered a reducing agent or passivating agent, primarily used in anaerobic environments (such as reducing Cr(VI) or passivating heavy metals). This invention breaks through this conventional thinking, cleverly utilizing the kinetic process of its transformation from a "reduced state (divalent)" to an "oxidized state (trivalent)" under aerobic (oxygenated) conditions. In this transformation process, FeS is no longer simply a reducing agent or passivating agent, but becomes a "microreactor" that continuously generates reactive oxygen species (ROS), opening up a new pathway for advanced oxidation of reducing iron-based materials under aerobic conditions.

[0160] 2. Unlike the universal theory in traditional Fenton-like reactions that uses hydroxyl radicals (•OH) as the core oxidation motive force, this invention, through rigorous mechanistic studies, confirms that in the CMC-FeS oxidation conversion system, superoxide radicals (•O2) are the primary oxidation motive force. - The contribution rate of ) is as high as 77.5%, far exceeding that of •OH. The discovery of this mechanism provides new theoretical support for the efficient oxidation of Sb(III), proving that CMC-FeS has a unique electron transfer pathway under specific aerobic / neutral conditions, which is different from the traditional iron oxidation process.

[0161] 3. Conventional antimony pollution treatment requires first oxidizing Sb(III) with an oxidant (such as potassium permanganate or ozone), followed by immobilization with an adsorbent. This invention achieves a highly efficient leap from "stepwise treatment" to a "one-step method." While CMC-FeS is being oxidized, its structure spontaneously evolves into iron (hydroxy) oxides, which can instantly and firmly lock the oxidation product Sb(V) into the mineral lattice through structural doping. This dynamic process of "simultaneous oxidation, mineralization, and immobilization" has a stronger immobilization effect.

[0162] 4. Addressing the engineering bottleneck of FeS particles' tendency to aggregate and hindered migration within formations, this invention introduces sodium carboxymethyl cellulose (CMC) to modify FeS. CMC molecules resolve the aggregation problem through steric hindrance and electrostatic repulsion, reducing FeS particle size, increasing specific surface area, and enhancing reaction sites. This allows the material to be directly injected and added to groundwater systems, and also enables rapid oxidation upon contact with oxygen, solving the problems of "difficulty in penetration, slow movement, and slow reaction" in in-situ remediation.

[0163] 5. Many advanced oxidation processes (AOPs) rely on strongly acidic environments (such as the traditional Fenton reaction at pH 2-3). This invention demonstrates that CMC-FeS exhibits optimal remediation performance under neutral conditions (around pH 7.0). This perfectly matches the actual pH environment of natural groundwater, eliminating the need for pH adjustment, significantly reducing remediation costs and secondary disturbances to the ecological environment, and possessing strong potential for practical engineering applications.

[0164] This invention provides a novel pathway for inducing endogenous ROS generation using CMC-FeS under aerobic conditions. Through efficient oxidation mediated by superoxide radicals and the immediate co-precipitation of newly formed iron (hydroxyl) oxides, trivalent antimony is simultaneously transformed from a highly toxic free state to a low-toxicity mineral fixed state. Its high efficiency in neutral environments and excellent soil mobility provide a synergistic remediation solution for the in-situ treatment of antimony pollution in groundwater, a solution not previously disclosed in existing technologies.

[0165] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A method for the low-toxicity transformation and structural locking of trivalent antimony in groundwater, characterized in that, include: A suspension of sodium carboxymethyl cellulose-stabilized ferrous sulfide nanomaterials was added to a water body containing trivalent antimony to obtain a composite solution. The solution was then subjected to a shaking reaction at room temperature and under aerobic conditions to allow the sodium carboxymethyl cellulose-stabilized ferrous sulfide nanomaterials to adsorb trivalent antimony and oxidize the trivalent antimony to pentavalent antimony. Before the shaking reaction, the concentration of sodium carboxymethyl cellulose-stabilized ferrous sulfide nanomaterials in the composite solution was 28.5~31.5 mg / L.

2. The method for low-toxicity transformation and structure-locking of trivalent antimony in groundwater according to claim 1, characterized in that, Before the oscillation reaction, the concentration of trivalent antimony in the composite solution was 9.6~10.5 mg / L.

3. The method for low-toxicity transformation and structure-locking of trivalent antimony in groundwater according to claim 1, characterized in that, The concentration of sodium carboxymethyl cellulose-stabilized ferrous sulfide nanomaterials in the suspension is 490~510 mg / L.

4. The method for low-toxicity transformation and structure-locking of trivalent antimony in groundwater according to claim 1, characterized in that, The pH value of the composite solution is 4.5-8.

5.

5. The method for low-toxicity transformation and structure-locking of trivalent antimony in groundwater according to claim 1, characterized in that, The oscillatory reaction takes place under dark conditions.

6. The method for low-toxicity transformation and structure-locking of trivalent antimony in groundwater according to claim 1, characterized in that, The method for preparing the suspension includes the following steps: Step 1: Under a nitrogen or inert gas atmosphere, mix the soluble ferrous salt solution and the sodium carboxymethyl cellulose aqueous solution until homogeneous to obtain a first mixture. The ratio of soluble ferrous salt in the soluble ferrous salt solution to sodium carboxymethyl cellulose in the sodium carboxymethyl cellulose aqueous solution is (0.465~0.485):0.086 by mass. Step 2: Under a nitrogen or inert gas atmosphere, mix the sulfide aqueous solution and all of the first mixture from Step 1 until homogeneous, seal, and let stand in an anaerobic environment at room temperature for at least 24 hours to obtain the suspension. The ratio of the soluble ferrous salt in the first mixture to the sulfide in the sulfide aqueous solution is (0.465~0.485):(0.57~0.59) by mass.

7. The method for low-toxicity transformation and structure-locking of trivalent antimony in groundwater according to claim 6, characterized in that, In step 1, the method for obtaining a soluble ferrous salt solution includes: mixing soluble ferrous salt and first water until homogeneous to obtain a soluble ferrous salt solution, wherein the mass fraction of soluble ferrous salt and the volume fraction of first water are (0.465~0.485):200, the mass fraction is in g and the volume fraction is in mL.

8. The method for low-toxicity transformation and structure-locking of trivalent antimony in groundwater according to claim 6, characterized in that, In step 2, the method for obtaining the sulfide aqueous solution includes: mixing the sulfide and the third water until homogeneous to obtain the sulfide aqueous solution, wherein the mass fraction of the sulfide and the volume fraction of the third water are (0.57~0.59):100, the mass fraction is in g and the volume fraction is in mL.

9. The method for low-toxicity transformation and structure-locking of trivalent antimony in groundwater according to claim 6, characterized in that, The soluble ferrous salt is ferrous chloride tetrahydrate.

10. The method for low-toxicity transformation and structure-locking of trivalent antimony in groundwater according to claim 6, characterized in that, The sulfide is sodium sulfide nonahydrate.

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