A method for preparing and applying a self-modified iron-based material for removing heavy metals and organic pollutants.

Abstract

This invention discloses the preparation and application of self-modified iron-based materials for removing heavy metal and organic pollutants. Acidophilic bacteria with stable iron-oxidizing capabilities are cultured in a medium and collected by centrifugation to obtain a large number of bacterial cells. These cells are then added to a culture medium to synthesize iron-containing secondary minerals, which are then pyrolyzed to form modified iron-based materials. Alternatively, the bacterial cells are added to iron-containing culture media with different concentrations of aluminum ions to synthesize aluminum ion-modified iron-based biomaterials of different morphologies and sizes. This product is synthesized by bacteria at room temperature, with the self-modification process of the iron-based material driven under pyrolysis conditions or an aluminum ion environment. It is environmentally friendly and allows for controllable synthesis. It is suitable for treating wastewater containing different types and concentrations of heavy metal and organic pollutants, with high treatment efficiency. Cr(VI) removal rate reaches over 90%, and organic pollutant removal rate reaches 100%. The material is recyclable and has broad application prospects.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a method for preparing self-modified iron-based materials for removing heavy metal and organic pollutants and their application in the treatment of wastewater containing heavy metals and organic pollutants. Background Technology

[0002] Heavy metal and organic pollution in wastewater is a widespread problem globally. Heavy metal pollution, due to its acute toxicity, non-biodegradability, and bioaccumulation, has become a hot topic in environmental remediation research. Taking chromium as an example, chromate passivation is commonly used to slow down metal surface corrosion in cooling circuits, chromite mining, and electroplating processes. Furthermore, the wood processing, textile printing and dyeing, pigment, and leather processing industries all use chromates as raw materials, generating large amounts of chromium-containing wastewater. Hexavalent chromium in the natural environment is toxic and difficult to degrade, posing a potential toxic effect on humans through bioaccumulation in the food chain. Hexavalent chromium can cause irreversible changes in human protein structure, thus affecting tissue cell function and human health. Other common heavy metals, such as Cu(II), Zn(II), Cd(II), Pb(II), and As(III), exhibit similar properties.

[0003] Among organic pollutants, antibiotic pollution and dyeing wastewater are typical examples. Antibiotics often enter the aquatic environment through medical wastewater, aquaculture wastewater, and agricultural wastewater, which may lead to the spread of antibiotic resistance genes, disruption of aquatic ecosystems, and even pose a potential threat to human health. Florfenicol (C...) 12 H 14 Taking Cl2FNO4S as an example, this is a broad-spectrum antibiotic widely used to treat animal infections, commonly used in aquaculture and poultry farming. Unmetabolized florfenicol is released into the environment through animal feces and urine; it is biotoxic, causing various forms of damage to organisms, and is also stable, making spontaneous hydrolysis difficult. Dyeing and printing wastewater is characterized by high COD, high SS concentration, complex composition, and the presence of biotoxic substances. It also features large volume, significant water quality variations, high color, large pH fluctuations, affecting biochemical treatment effectiveness, and intermittent discharge, leading to high treatment costs and significant treatment difficulties. Due to technical and economic reasons, most biological and physical treatment methods can only meet basic discharge requirements. Organic matter is merely decomposed into smaller substances; the properties of these decomposition products are difficult to control and manage, and it cannot be guaranteed that they will not harm the environment. Currently, strategies for treating organic pollutants in wastewater include physical adsorption, biodegradation, and electrochemical degradation, but these are sometimes inefficient. In recent years, Fenton oxidation for pollutant removal has become a major research hotspot in wastewater treatment. This method refers to the reaction of H2O2 with Fe... 2+ In the mixed system, Fe 2+The Fenton process triggers a chain reaction that catalyzes the decomposition of H2O2, generating various reactive oxygen species that attack and break or open the bonds of recalcitrant compounds. The main problems with the Fenton process for wastewater treatment are strict pH control, large amounts of iron sludge production, and the inability to reuse the catalyst, leading to reagent waste.

[0004] To address the problem that traditional water treatment methods are not very efficient at treating heavy metal and organic pollutants, this invention proposes an improved method that uses acidophilic bacteria to synthesize iron-based secondary minerals.

[0005] In acidic mine wastewater, many types of acidophilic bacteria can synthesize iron-based secondary minerals. For example, *Acidithioobacillus ferrooxidans* can promote the oxidation of low-valent iron in the environment, causing it to aggregate. Simultaneously, its extracellular macromolecules (such as polysaccharides and proteins) can bind to the aggregated iron, depositing it as iron-based minerals. This bacterium can accelerate the oxidation of ferrous ions in acidic environments, increasing the oxidation rate to 10 times that under sterile conditions. 5 -10 8 The iron ions obtained from oxidation react with various anions in the mining environment (such as SO42-). 2- After combining, a large number of iron-based secondary minerals were formed.

[0006] This invention uses acidophilic bacteria to synthesize iron-based secondary mineral materials in an iron-containing culture medium. Through pyrolysis or the addition of aluminum ions, the materials undergo self-modification, resulting in morphological and compositional changes that are conducive to the removal of heavy metals or the degradation of organic pollutants by catalytic Fenton reactions. It exhibits good removal performance of heavy metal pollutants and organic pollutants in a short period of time. Summary of the Invention

[0007] To address the aforementioned problems, the present invention aims to provide a self-modified iron-based material for removing heavy metal and organic pollutants, along with its preparation and application methods.

[0008] This invention provides a method for preparing a self-modified iron-based material for removing heavy metal and organic pollutants, comprising the following steps:

[0009] (1) Add the cultured acidophilic bacteria with stable iron oxidation ability to a culture medium with pH=1.5-2.5 to synthesize iron-containing secondary minerals and then pyrolyze them to form modified iron-based materials; or add the bacteria to an iron-containing culture medium with added aluminum ions to synthesize aluminum sulfate-modified secondary minerals and then pyrolyze them to form aluminum ion-modified iron-based biomaterials.

[0010] The pyrolysis is performed using a tubular furnace, with N2 flowing through the entire process to create a strictly anaerobic environment. The heating rate is constant, and once the target temperature is reached, the temperature must be maintained at a constant temperature before being slowly reduced to room temperature.

[0011] (2) After filtration, washing, drying and grinding, a self-modified iron-based material is obtained.

[0012] Specifically, acidophilic bacteria must possess iron oxidation capabilities, and are selected from Acidithiobacillus ferrooxidans, Acidithiobacillus caldus, Leptospirillum ferriphilum, Leptospirillum ferrooxidans, etc.

[0013] Among them, the synthesized iron-based secondary minerals are weakly crystalline iron sulfate hydroxyl minerals, such as jaundice, Schiele minerals, and ammonium jaundice.

[0014] In a specific embodiment, during the expansion culture of the acidophilic bacteria cells with stable iron oxidation ability, the initial pH of the culture medium is 1.5-2.5, the temperature is 25-45℃, the rotation speed is 170-200 rpm, and the time is 2-4 days. After the expansion culture is completed, the bacterial cells are collected by centrifugation, washed with deionized water at pH 1.5-2.5, mixed well, and then used in subsequent steps.

[0015] More specifically, 9K medium (3 g / L (NH4)2SO4, 0.5 g / L K2HPO4, 0.1 g / L KCl, 0.5 g / L MgSO4·7H2O) with pH=2 supplemented with FeSO4·7H2O as energy was used to expand the culture to the logarithmic phase in a shaker at 30°C and 180 rpm. The culture was then centrifuged at 10,000 rpm for 15 min in a low-temperature centrifuge. After filtering to remove solids, the culture was washed with sterile water at pH=2 for later use.

[0016] When synthesizing the material, the initial pH of the culture medium is 1.5-2.5, the temperature is 25-45℃, the rotation speed is 170-200 rpm, and the time is 6-8 days.

[0017] Preferably, in step (1), the pH is adjusted to pH=1.5-2.5 using sulfuric acid, Fe(NH4)2(SO4)2·6H2O is added to the culture medium for synthesizing ammonium ferrous sulfate, FeSO4·7H2O or K2SO4 is added to the culture medium for synthesizing potassium ferrous sulfate, or FeSO4·7H2O is added to the 9K culture medium, and FeSO4·7H2O is added to the culture medium for synthesizing Scheres mineral;

[0018] The pyrolysis operation is carried out in a tube furnace with N2 flowing through it throughout. The material is heated to 450-550°C for 60-70 minutes, and the temperature is maintained at a steady rate during the heating process. After reaching the target temperature, it is kept at a constant temperature for 90-150 minutes. Then it is slowly cooled to room temperature. When synthesizing aluminum sulfate-modified secondary minerals, aluminum sulfate is added at an Al:Fe ratio of 0.1:1 to 1:1.

[0019] In a specific implementation, after the material is synthesized, it is filtered and collected, washed with deionized water at pH 1.5-2.5, and dried at low temperature in a vacuum drying oven; grinding is done using an agate mortar.

[0020] The present invention provides a preparation method for obtaining self-modified iron-based materials.

[0021] The present invention also provides the application of the self-modified iron-based material in the removal of heavy metals or organic pollutants in water. Specifically, the heavy metals are one or more of Cr(VI), Cu(II), Zn(II), Cd(II), Pb(II) and As(III); and the organic pollutants are one or more of antibiotics such as florfenicol and chloramphenicol, and dyes such as rhodamine B and methylene blue.

[0022] The present invention further provides a method for removing heavy metal pollution in water, which involves adding the self-modified iron-based material to waste liquid containing heavy metals, operating at a temperature of 20-40℃, an initial pH value of 3-11, a rotation speed of 170-200 rpm, a treatment time of 20-120 min, and separating the treated waste liquid and material by centrifugation.

[0023] Alternatively, under the condition of adding strong oxidants such as hydrogen peroxide or persulfate, the modified iron-based material is added to the waste liquid containing organic pollutants for removal. The operating temperature is 20-40℃, the initial pH value is 3-9, the rotation speed is 170-200rpm, and the treatment time is 20-240min. The treated waste liquid and material are separated by centrifugation.

[0024] Specifically, after use, the modified iron-based material is rinsed with an aqueous solution of pH 1.5-2.5 and then recycled, for example, 2-6 times.

[0025] Due to the adoption of the above solution, the beneficial effects of the present invention are:

[0026] The preparation of self-modified iron-based materials using this invention involves simple and straightforward steps, and the reagents and methods employed are relatively inexpensive and readily available, facilitating large-scale industrial production. The modified iron-based materials obtained by this invention exhibit high and stable removal efficiency for heavy metals and organic pollutants, with minimal impact from pH, environmental ions, and organic matter. The modified iron-based materials also possess strong recyclability, allowing for multiple uses after filtration, washing, and drying. Furthermore, the modified iron-based materials obtained by this invention can achieve complete degradation and mineralization of low-concentration, difficult-to-treat organic pollutants. Attached Figure Description

[0027] Figure 1 The images show scanning electron microscope (SEM) images of modified ammonium ferric sulfate and potassium ferric sulfate at different pyrolysis temperatures in this invention. In the images, unmodified biosynthetic ammonium ferric sulfate is named A1, unmodified potassium ferric sulfate is named A2, ammonium ferric sulfate modified at 500℃ is named B1, potassium ferric sulfate modified at 500℃ is named B2, ammonium ferric sulfate modified at 200℃ is named F1, potassium ferric sulfate modified at 200℃ is named F2, ammonium ferric sulfate modified at 900℃ is named F3, and potassium ferric sulfate modified at 900℃ is named F4.

[0028] Figure 2 This is an XPS diagram of Fe and S elements in ammonium ferric sulfate and potassium ferric sulfate before and after pyrolysis modification at 500℃ in this invention. In the figure, a and b represent ammonium ferric sulfate before modification, A and B represent ammonium ferric sulfate after pyrolysis modification at 500℃; c and d represent potassium ferric sulfate before modification, C and D represent potassium ferric sulfate after pyrolysis modification at 500℃, and a, c, A, and C represent Fe2p, while b, d, B, and D represent S2p.

[0029] Figure 3 The images show scanning electron microscope (SEM) images of potassium ferric sulfate modified with aluminum sulfate and Schiele minerals in this invention. Each set of SEM images, from left to right, shows the same material under different magnifications in the SEM.

[0030] Figure 4 The figures show the time versus Cr(VI)C / CO curves and termination pH of the thermally modified materials at 200℃ and 900℃ over 120 min in this invention. In the figures, Aj represents ammonium ferric sulfate, J represents potassium ferric sulfate, and the numbers represent the modification temperature.

[0031] Figure 5 The curves of time versus Cr(VI)C / CO for 500℃ modified (N2) and unmodified ammonium ferric sulfate and potassium ferric sulfate within 120 min are shown in the figure.

[0032] Figure 6The figure shows the C / C0 curves of florfenicol concentration over 240 min with different Al:Fe ratio modified materials in this invention under the addition of H2O2 or PMS. The numbers in the legend represent the Al:Fe ratio. In the figure, A and B represent the addition of H2O2, and C and D represent the addition of PMS; A and C represent the addition of different aluminum sulfate-modified jasper (Jar), ​​and B and D represent the addition of different aluminum sulfate-modified Schehertz minerals (Sch).

[0033] Figure 7 To illustrate the effect of different Al:Fe ratios on Rhodamine B concentration C / C0 curves over 180 min using modified materials of different strong oxide ratios in this invention, the figures in parentheses represent the Al:Fe ratio. In the figures, AC represents the removal of Rhodamine B by aluminum sulfate-modified Schönbach's mineral under the addition of PDS, PMS, and H2O2, respectively; DF represents the changes in PDS, PMS, and H2O2 in the aluminum sulfate-modified Schönbach's mineral catalytic system; ac represents the removal of Rhodamine B by aluminum sulfate-modified potassium ferric sulfate under the addition of PDS, PMS, and H2O2, respectively; and df represents the changes in PDS, PMS, and H2O2 in the aluminum sulfate-modified potassium ferric sulfate catalytic system.

[0034] Figure 8 The curves of time versus Cr(VI)C / CO and the termination pH of the modified ammonium ferric sulfate at 500℃ over 120 min are shown for different initial pH values.

[0035] Figure 9 The C / C0 curves of florfenicol concentration over 180 min were obtained for Al:Fe = 0.5:1 modified jasmine and Schiele minerals in this invention under different initial pH conditions and with the addition of H2O2.

[0036] Figure 10 The time versus Cr(VI)C / CO curves of modified ammonium ferric sulfate at 500℃ over 120 min under different anion addition conditions in this invention.

[0037] Figure 11 For different anion addition conditions, the time-to-Rhodamine BC / CO curves of Al:Fe = 0.5:1 modified Scheres mineral (Al) and Al:Fe = 1:1 modified jaundice (Al) in this invention within 120 min were compared.

[0038] Figure 12 The time versus Cr(VI)C / CO curves of modified ammonium ferric sulfate at 500℃ over 120 min were obtained under different organic acid addition conditions. Detailed Implementation

[0039] The present invention will be further described below with reference to the accompanying drawings and specific examples, but not as a limitation thereof.

[0040] Example 1

[0041] This embodiment describes a method for preparing a self-modified iron-based material for removing heavy metal and organic pollutants, comprising the following steps:

[0042] (1) Scale-up culture of strains used to synthesize iron-based materials

[0043] FeSO4·7H2O was added to 9K medium to achieve a final concentration of 44.78 g / L, and the pH was adjusted to 2 with sulfuric acid. Acidithiobacillus ferrooxidans, possessing stable iron-oxidizing ability, was cultured in a shaker at 30°C and 180 rpm until the logarithmic growth phase (approximately 3 days). After filtering to remove solids, the cells were centrifuged at 10,000 rpm for 15 minutes. The collected cells were washed twice with sterile water at pH 2.0, and a small amount of sterile water at pH 2 was added to obtain a bacterial suspension.

[0044] (2) Iron-based material synthesis and modification are carried out separately.

[0045] The synthesis and modification of materials used for the removal of heavy metal pollutants are carried out separately, and the specific steps are as follows:

[0046] Add 250 mL of deionized water (pH = 2) to a 500 mL shake flask, then add an equal volume of bacterial suspension. Divide the shake flasks into two groups: one group contains 25 g of Fe(NH4)2(SO4)2·6H2O for the synthesis of ammonium ferrous sulfate; the other group contains 11.12 g of FeSO4·7H2O and 1.16 g of K2SO4 for the synthesis of potassium ferrous sulfate. Incubate on a shaker at 30°C and 180 rpm for 7 days. Filter and collect the synthesized products, wash three times with deionized water (pH = 2.0), and dry in a vacuum drying oven.

[0047] Dry flavonoids and ammonium flavonoids were thermally modified using a tube furnace. Under a stable nitrogen atmosphere throughout the process, the temperature was raised from room temperature to 200°C over 24 minutes, to 500°C over 65 minutes, and to 900°C over 120 minutes, respectively. The temperature was maintained at a steady rate during heating. After reaching the target temperature, it was held constant for 120 minutes, and then slowly cooled to room temperature. Six thermally modified materials were obtained under nitrogen atmosphere.

[0048] Scanning electron microscope (SEM) spectra of eight materials before and after modification are shown below. Figure 1As shown, the unmodified biosynthetic ammonium ferrous sulfate is named A1, the unmodified potassium ferrous sulfate is named A2, the ammonium ferrous sulfate modified at 500℃ is named B1, the potassium ferrous sulfate modified at 500℃ is named B2, the ammonium ferrous sulfate modified at 200℃ is named F1, the potassium ferrous sulfate modified at 200℃ is named F2, the ammonium ferrous sulfate modified at 900℃ is named F3, and the potassium ferrous sulfate modified at 900℃ is named F4.

[0049] Figure 2 XPS results of Fe and S in the materials before and after pyrolysis modification at 500℃ are presented. The forms of Fe in biosynthesized ammonium ferrous sulfate and potassium ferrous sulfate are significantly altered. XPS detected the newly formed Fe(II), and based on peak area analysis, its proportion of total iron is greater than that of Fe(III). Compared to the modified ferrous sulfate, the modified ammonium ferrous sulfate has a higher Fe(II) proportion. Sulfate remains the predominant form of S both before and after modification.

[0050] (3) The synthesis and modification of materials for the removal of organic pollutants are carried out simultaneously.

[0051] The specific steps are as follows:

[0052] Add 300 mL of 9K medium (pH 2) to a 500 mL shake flask, then add 35 g of FeSO4·7H2O, followed by an equal volume of bacterial suspension. Divide the shake flasks into four groups and add different masses of Al2(SO4)3·12H2O (calculated as Al:Fe ratios of 0:1, 0.1:1, 0.5:1, and 1:1) to synthesize aluminum sulfate-modified iron-based biomaterials with different morphologies and sizes. After incubation at 30°C and 180 rpm for 7 days on a shaker, the synthesized material is collected by filtration and dried in a vacuum drying oven.

[0053] The morphology of Schiele minerals (without aluminum sulfate, with aluminum sulfate) and japotassium ferrophosphate under scanning electron microscopy is as follows: Figure 3 As shown, the material exhibits significant morphological changes in the aluminum sulfate-added system.

[0054] Example 2

[0055] This example illustrates the effect of different pyrolysis temperatures on the removal of heavy metal contaminants by modified materials. 8.5 g of potassium dichromate was added to 1 L of deionized water to prepare a 3 g / L Cr(VI) solution. 96.5 ml of deionized water was added to a 150 ml Erlenmeyer flask, followed by 3.5 ml of Cr(VI) solution, to form a 105 mg / L chromium solution system.

[0056] 0.1 g each of the six iron-based materials prepared by thermal modification at different temperatures for heavy metal removal, synthesized in Example 1, were added to the conical flasks described above. The reaction was carried out in a constant-temperature shaking incubator at 30°C and 180 rpm. Samples were taken every 10 minutes from 0 to 40 minutes, and every 20 minutes thereafter, with 1 mL taken each time. The supernatant was collected by centrifugation. The Cr(VI) concentration was determined using the diphenylcarbazide spectrophotometric method. After the reaction was completed at 120 minutes, the pH of the reaction system was measured.

[0057] Depend on Figure 4 The Cr(VI) removal rate is only about 20% within 100 min after pyrolysis modification at 200℃ and 900℃.

[0058] Depend on Figure 5 The removal rate of Cr(VI) by pyrolysis modified potassium ferric alum at 500℃ reached 70% within 120 minutes, and the removal rate of Cr(VI) by thermal modification at 500℃ reached over 90% within 120 minutes, and the maximum removal rate was reached in about 20 minutes, demonstrating a good removal effect of Cr(VI).

[0059] Example 3

[0060] This embodiment investigates the effect of different amounts of aluminum sulfate added during the modification of modified iron-based minerals on the removal of organic pollutants, antibiotic florfenicol, and dye rhodamine B.

[0061] (1) Effect of different aluminum sulfate dosages on the removal of florfenicol from materials.

[0062] Prepare a 10 mg / L florfenicol solution by adding 10 mg of florfenicol to 1 L of ultrapure water and sonicating for 1.5 h to ensure the florfenicol is completely and uniformly dissolved in the water. Measure 100 mL of the solution into a 250 mL Erlenmeyer flask each time. Prepare 0.5 M persulfate (PMS) and 0.5 M H₂O₂ solutions.

[0063] The conical flasks were divided into PMS and H2O2 groups. 0.1 g each of the eight iron-based materials synthesized in different aluminum sulfate media for organic pollutant removal, as described in Example 1, were added to the conical flasks. Then, 1 mL of either PMS or H2O2 stock solution was added according to the flask group. The reaction was carried out in a constant-temperature shaking incubator at 30°C and 180 rpm. Timing was started immediately after the addition of the oxidant. The total reaction time was 4 hours. Samples were taken every 40 minutes, with 0.75 mL of sample solution added to 0.75 mL of pure methanol solution and immediately shaken to quench free radical reactions. The filtrate was collected through a 0.22 μm organic filter membrane. Using pure methanol and ultrapure water as the mobile phase, high-performance liquid chromatography (HPLC) at 220 nm was used to determine the concentration of florfenicol in the sample solution.

[0064] Depend on Figure 6 Among the modified Schiele minerals, Al:Fe = 1:1 and 0.5:1 showed the best catalytic degradation effect of florfenicol by H2O2 / PMS, while other modified materials also showed relatively good catalytic degradation ability.

[0065] (2) Effect of different aluminum sulfate dosages on the removal of rhodamine B from the material.

[0066] Prepare a 50 mg / L Rhodamine B solution by adding 50 mg of Rhodamine B to 1 L of deionized water, measuring 100 mL each time and pouring it into a 250 mL Erlenmeyer flask. Prepare 0.5 M persulfate (PDS), 0.5 M permonsulfate (PMS), and 10 g / L H2O2 solutions.

[0067] The conical flasks were divided into three groups: PDS, PMS, and H2O2. 0.1 g each of the eight iron-based materials synthesized with different amounts of aluminum sulfate for organic pollutant removal, as described in Example 1, were added to the conical flasks. Then, 1 mL of PDS, PMS, or H2O2 mother liquor was added according to the flask group. The reaction was carried out in a constant-temperature shaking incubator at 30°C and 180 rpm. Timing was started immediately after adding the oxidant. The total reaction time was 3 hours. Samples were taken every 30 minutes, with 0.75 mL of sample solution added to 0.75 mL of pure methanol solution and immediately shaken to quench free radical reactions. The filtrate was collected through a 0.22 μm organic filter membrane, and the absorbance was measured at 554 nm using a spectrophotometer to determine the concentration of Rhodamine B in the sample solution.

[0068] Depend on Figure 7 It can be seen that aluminum sulfate-modified Scherbach's minerals and potassium ferric sulfate both exhibited good efficiency in catalyzing the degradation of rhodamine B by PMS / PDS. Among the modified Scherbach's minerals, Al:Fe = 1:1 showed the best catalytic effect on the degradation of rhodamine B by hydrogen peroxide.

[0069] Example 4

[0070] This example illustrates the effect of initial pH on the removal of heavy metal and organic pollutants by modified materials.

[0071] (1) Effect of initial pH on the removal of heavy metal chromium by the material

[0072] First, dilute the 3 g / L potassium dichromate solution to 105 mg / L. Adjust the pH to 3, 5, 7, 9, and 11 using NaOH and dilute sulfuric acid solutions and set up parallel experimental groups. Weigh 0.1 g of 500℃ heat-modified ammonium ferric sulfate and add it to each reaction system. Subsequent operations are the same as in Example 2.

[0073] Depend on Figure 8It can be seen that the 500℃ thermally modified ammonium ferric sulfate prepared by the present invention has little effect on the removal of Cr(VI) in the water environment when the initial pH range is 3-11, and has good hexavalent chromium removal performance. The pH at the end of the experiment after 100 min is shown in the figure.

[0074] (2) Effect of initial pH on the removal of organic pollutant florfenicol by the material

[0075] Prepare a 10 mg / L florfenicol solution by adding 10 mg of florfenicol to 1 L of ultrapure water and sonicating for 1.5 h to ensure complete and uniform dissolution. Pour 100 mL of the solution into a 250 mL Erlenmeyer flask and adjust the pH to 3, 5, 7, 9, or 11 using NaOH and dilute sulfuric acid solutions. Prepare a 0.5 M H₂O₂ solution.

[0076] Add 0.1 g each of the aluminum sulfate-modified potassium ferrous sulfate (named Jar0.5) and the modified Sch0.5 mineral (named Sch0.5) synthesized in Example 1 for the removal of organic pollutants (Al:Fe = 0.5:1) to the conical flask above, and then add 1 mL of H2O2 mother liquor to each. The total reaction time is 3 hours, and samples are taken every 30 minutes. Other operations are the same as in Example 2 (1).

[0077] Depend on Figure 9 It can be seen that aluminum sulfate-modified potassium ferric sulfate has excellent catalytic degradation efficiency of florfenicol at an initial pH of 3, which decreases at pH of 5 and is strongly inhibited at pH ≥ 7.

[0078] Depend on Figure 9 It can be seen that aluminum sulfate-modified Scheres minerals exhibit excellent catalytic degradation efficiency of florfenicol at initial pH values ​​of 3-9, achieving almost complete degradation within 30 minutes. However, the catalytic degradation efficiency decreases at pH value of 11.

[0079] Example 5

[0080] Various anions are commonly found in aquatic environments rich in heavy metals and organic pollutants. This example investigates the impact of common environmental anions on the removal of heavy metal and organic pollutants by materials.

[0081] (1) Effect of anions on the removal of heavy metal chromium from materials

[0082] First, dilute the 3 g / L potassium dichromate solution to 105 mg / L. Then, add NaCl, NaHCO3, NaH2PO4, and NaNO3 mother liquors respectively to make the final concentration of the corresponding anions in the system 20 mg / L. Weigh 0.1 g of 500℃ heat-modified ammonium ferrous sulfate and add it to each reaction system. The subsequent operation is the same as in Example 2.

[0083] Depend on Figure 10 It can be seen that the addition of the four anions has little effect on the chromium removal efficiency. Nitrate ions have a certain inhibitory effect on chromium removal, while the other three anions have no effect. This indicates that the material prepared by this invention has strong resistance to complex anionic environments, and most common anions do not affect the chromium removal efficiency of the material.

[0084] (2) Effect of anions on the removal of organic pollutant Rhodamine B by materials

[0085] Prepare a 50 mg / L Rhodamine B solution by adding 50 mg of Rhodamine B to 1 L of deionized water. Measure 100 mL of each solution and pour it into a 250 mL Erlenmeyer flask. Divide the flasks into three groups and add Na₂SO₄, NaNO₃, and NaCl respectively to test the effects of sulfate, nitrate, and chloride ions on the removal of Rhodamine B by the material. Two final concentrations were set for each salt: 0.5 mM and 1 mM.

[0086] Prepare 0.5M persulfate (PDS), 0.5M permonsulfate (PMS) and 10 g / L H2O2 solutions.

[0087] Each large group of conical flasks was divided into three subgroups: PDS, PMS, and H2O2. 0.1 g each of the aluminum sulfate-modified potassium ferrous sulfate (Jar0.5) and the Al:Fe=1 modified Schl mineral (Sch1) synthesized in Example 1 for the removal of organic pollutants were added to each reaction system. Subsequent operations were the same as in Example 3(2).

[0088] Depend on Figure 11 It can be seen that the presence of chloride ions strongly promotes the degradation of rhodamine B by PMS catalyzed by aluminum sulfate-modified Schönbach's minerals, while sulfate and nitrate ions have little effect on the reaction; the presence of the three anions has a certain inhibitory effect on the degradation of rhodamine B by PDS catalyzed by modified Schönbach's minerals; the presence of chloride ions has a certain inhibitory effect on the degradation of rhodamine B by H2O2 catalyzed by modified Schönbach's minerals, while the presence of sulfate and nitrate ions has no significant inhibitory effect on the reaction.

[0089] Depend on Figure 11 It can be seen that the presence of the three anions has little effect on or may promote the degradation of Rhodamine B by PMS / PDS / H2O2 catalyzed by aluminum sulfate-modified potassium ferric sulfate.

[0090] Example 6

[0091] Various types of organic acids exist in different industrial wastewater environments. This example illustrates the effect of organic acids on the removal of heavy metal and organic pollutants by modified materials. First, a 3 g / L potassium dichromate solution was diluted to 105 mg / L. Then, different concentrations of humic acid (HA) mother liquor were added to achieve final humic acid concentrations of 10, 20, 30, and 40 mg / L, and citric acid (CA) and oxalic acid (OA) mother liquors were added to achieve a final organic acid concentration of 20 mg / L. Subsequent operations were the same as in Example 2. A control group of 40 mg / L humic acid was also set up without any added materials.

[0092] Depend on Figure 12 It can be seen that the three organic acids have no absolute effect on the removal effect of hexavalent chromium in this material, the concentration of humic acid does not have a correlation with the removal effect of chromium by the material, and citric acid can promote the removal of chromium to a certain extent.

Claims

1. A method for removing heavy metal pollution from water bodies, characterized in that, The self-modified iron-based material is added to waste liquid containing heavy metals. The operating temperature is 20-40℃, the initial pH value is 3-11, the rotation speed is 170-200 rpm, and the treatment time is 20-120 min. The treated waste liquid and material are separated by centrifugation. The preparation method of the self-modified iron-based material includes the following steps: (1) Add the cultured acidophilic bacteria cells with stable iron oxidation ability to a culture medium with pH=1.5-2.5 to synthesize iron-containing secondary minerals; (2) After the iron-containing secondary minerals are cultured and synthesized, they are filtered, washed, dried, and finally pyrolyzed; The iron-based secondary mineral synthesized in step (1) is potassium ferrous sulfate or ammonium ferrous sulfate; In step (1), sulfuric acid is used to adjust the pH to 1.5-2.

5. Fe(NH4)2(SO4)2·6H2O is added to the culture medium for synthesizing ammonium ferrous sulfate, or FeSO4·7H2O, K2SO4 or FeSO4·7H2O is added to the culture medium for synthesizing potassium ferrous sulfate. The pyrolysis described in step (2) involves heating the material to 450-550℃ for 60-70 minutes, maintaining a steady temperature rise during the heating process, and holding the temperature constant for 90-150 minutes after reaching the target temperature; then slowly cooling to room temperature; the pyrolysis is performed using a tube furnace with N2 flowing through throughout to create a strictly anaerobic environment, maintaining a constant heating rate, and holding the temperature constant after reaching the target temperature before slowly cooling to room temperature; The heavy metal in question is Cr(VI).

2. A method for removing organic pollutants from water bodies, characterized in that, Under the condition of adding strong oxidants such as hydrogen peroxide or persulfate, aluminum ion-modified iron-based materials are added to waste liquid containing organic pollutants for removal. The operating temperature is 20-40℃, the initial pH value is 3-9, the rotation speed is 170-200 rpm, and the treatment time is 20-240 min. The treated waste liquid and materials are separated by centrifugation. The preparation method of the aluminum ion-modified iron-based material includes the following steps: (1) The acidophilic bacteria cells with stable iron oxidation ability were added to an iron-containing medium with pH=1.5-2.

5. Aluminum sulfate was added to the iron-containing medium to synthesize iron-based secondary minerals modified with aluminum sulfate. (2) After the secondary minerals are cultured and synthesized, they are filtered, washed, and dried; The iron-based secondary mineral synthesized in step (1) is jaundice or Schiele mineral; In step (1), sulfuric acid is used to adjust the pH to 1.5-2.

5. FeSO4·7H2O or K2SO4 is added to the culture medium for synthesizing potassium ferrous sulfate, or FeSO4·7H2O is added to the 9K culture medium, or FeSO4·7H2O is added to the culture medium for synthesizing Scheres mineral. In step (1), aluminum sulfate is added at a ratio of Al:Fe of 0.1:1 to 1:

1. The organic pollutant is florfenicol or rhodamine B.

3. The method according to claim 1 or 2, characterized in that, Acidophilic bacteria must have the ability to oxidize iron, and are selected from Acidithiobacillus ferrooxidans, Acidithiobacillus caldus, Leptospirillum ferriphilum, or Leptospirillum ferrooxidans.

4. The method according to claim 1 or 2, characterized in that, During the expansion culture of the acidophilic bacteria with stable iron oxidation ability, the initial pH of the culture medium is 1.5-2.5, the temperature is 25-45℃, the rotation speed is 170-200 rpm, and the time is 2-4 days. After the expansion culture is completed, the bacterial cells are collected by centrifugation, washed with deionized water at pH 1.5-2.5, mixed well, and then used in subsequent steps.

5. The method according to claim 4, characterized in that, The culture medium is a 9K medium with pH=2 using FeSO4·7H2O as an energy source. The composition of the medium is: 3 g / L (NH4)2SO4, 0.5 g / L K2HPO4, 0.1 g / L KCl, and 0.5 g / L MgSO4·7H2O. The medium is cultured in a shaker at 30℃ and 180 rpm until the logarithmic phase. It is then centrifuged at 10,000 rpm for 15 min in a low-temperature centrifuge. After filtering to remove solids, the medium is washed with sterile water at pH=2 for later use. When synthesizing materials, the initial pH of the culture medium should be 1.5-2.5, the temperature should be 25-45℃, the rotation speed should be 170-200 rpm, and the time should be 6-8 days.

6. The method according to claim 1 or 2, characterized in that, After the materials are synthesized, they are collected by filtration, washed with deionized water at pH 1.5-2.5, and dried in a vacuum drying oven at low temperature; grinding is done using an agate mortar.

7. The method as described in claim 1 or 2, characterized in that, After use, the self-modified iron-based material or the aluminum ion-modified iron-based material can be rinsed with a pH 1.5-2.5 aqueous solution and then recycled 2-6 times.

Images