Modified zero-valent iron preparation for sterilization and algae removal in water and preparation method thereof
By modifying zero-valent iron with silicate and carbonate, its adsorption and redox capabilities are enhanced, which solves the problem of easy passivation of zero-valent iron during use in water bodies, achieves efficient removal of microorganisms, and expands its application in water purification.
Patent Information
- Application Number
- CN202411845336.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-16
- Publication Date
- 2025-09-30
- Estimated Expiration
- 2044-12-16
AI Technical Summary
Zero-valent iron is easily passivated during use, resulting in a decrease in its adsorption and redox capabilities, limiting its application in removing pathogenic microorganisms in water bodies. In addition, the reactive oxygen species have a short half-life and a small migration distance, which affects the disinfection effect.
Zero-valent iron was modified with silicate and carbonate, and functional groups were introduced on the surface of the zero-valent iron by mechanical ball milling to enhance its adsorption and redox capabilities. Modified zero-valent iron preparations were prepared for sterilization and algae removal in water.
It improves the adsorption and redox ability of zero-valent iron on microorganisms, enhances the efficiency of removing water-polluting microorganisms, and broadens the application of zero-valent iron in the field of water purification.
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Figure CN119750730B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of zero-valent iron modification, and in particular to a modified zero-valent iron preparation for sterilization and algae removal in water and a preparation method thereof. Background Art
[0002] Pathogens and algae in water are common microbial contaminants that pose serious health risks and ecological problems. Algal pollution leads to algal blooms, which can cause aquatic organisms to die from lack of oxygen, resulting in a black and smelly water. Some algae release algal toxins, seriously affecting water quality. Chemical methods, such as chlorine disinfection and copper reagent treatment, are often used to eliminate pathogens and algae in water. However, these chemicals can be toxic to aquatic ecosystems, affect water quality, and easily lead to drug resistance. Furthermore, they can generate harmful disinfection byproducts. Zero-valent iron (ZVI) is one of the most popular materials currently receiving significant attention in the environmental field. Its high reducibility and large specific surface area make it suitable for use as an adsorbent and reducing agent to remove harmful substances. ZVI has a significant killing effect on Gram-negative and Gram-positive bacteria, as well as algae. Its mechanisms primarily involve redox reactions such as physical adsorption and inactivation of reactive oxygen species. However, zero-valent iron is easily passivated during use and storage, forming a dense oxide shell on the surface, which reduces the adsorption active sites on the ZVI surface, hinders the outward transfer of iron core electrons, and reduces the generation of reactive oxygen species, resulting in a decrease in its adsorption, redox and other abilities, limiting the disinfection effect. In addition, the reactive oxygen species generated by zero-valent iron have a short half-life, a small migration distance, a low steady-state concentration, and a low effective utilization rate of free radicals in reactions with bacteria. These defects limit the large-scale application of ZVI in the removal of pathogenic microorganisms in water bodies. Therefore, it is necessary to select suitable modifiers to regulate the ZVI shell structure and improve its reaction activity, while finding effective coupled adsorption-inactivation technologies to sterilize at the zero-valent iron interface and enhance the ability of zero-valent iron to remove bacteria.
[0003] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute prior art known to ordinary technicians in the field. Summary of the Invention
[0004] In view of this, the present invention proposes a modified zero-valent iron preparation for sterilization and algae removal in water and a preparation method thereof. By combining silicate-modified zero-valent iron with carbonate-modified zero-valent iron, the adsorption of bacteria and the production of reactive oxygen species are simultaneously improved, thereby achieving effective coupling of microbial adsorption on the zero-valent iron surface and in situ oxidative inactivation, overcoming the defects of short lifespan and small migration distance of reactive oxygen species, and realizing efficient removal of microorganisms in water.
[0005] The technical solution of the present invention is achieved as follows: The present invention provides a modified zero-valent iron preparation for sterilization and algae removal in water, comprising silicate-modified zero-valent iron and carbonate-modified zero-valent iron; the mass ratio of the silicate-modified zero-valent iron to the carbonate-modified zero-valent iron is 1:(0.8-1.2);
[0006] In the silicate-modified zero-valent iron, the molar ratio of silicate to zero-valent iron is (3-8):100;
[0007] In the carbonate-modified zero-valent iron, the molar ratio of carbonate to zero-valent iron is (3-8):100.
[0008] The present invention also provides a use of the modified zero-valent iron preparation for sterilization and algae removal in water in the preparation of a water microorganism removal product.
[0009] On the basis of the above technical solution, preferably, the water microorganism removal product includes an adsorbent for water microorganisms.
[0010] On the basis of the above technical solution, preferably, the water microorganism removal product includes a biocide for water microorganisms.
[0011] The present invention also provides a method for preparing the modified zero-valent iron preparation for sterilization and algae removal in water, comprising the following steps:
[0012] S10, obtaining zero-valent iron powder, carbonate, and silicate;
[0013] Add carbonate and zero-valent iron powder into the first ball mill according to a molar ratio of (3-8):100;
[0014] Add silicate and zero-valent iron powder into the second ball mill according to the molar ratio of (3-8):100;
[0015] S20, performing mechanical ball milling in the first ball mill and the second ball mill to obtain silicate-modified zero-valent iron and carbonate-modified zero-valent iron, respectively;
[0016] S30. Mixing silicate-modified zero-valent iron and carbonate-modified zero-valent iron in a mass ratio of 1:(0.8-1.2) to obtain a modified zero-valent iron preparation.
[0017] In this embodiment, reduced iron powder can be used as the main component of zero-valent iron powder, and carbonates and silicates are selected as modification materials. Through functional surface modification, specific functional groups are introduced on the surface of zero-valent iron to optimize the surface modification of the material, so as to improve the selectivity, adsorption capacity and reaction activity of the material for Escherichia coli.
[0018] In this embodiment, to prevent agglomeration of the zero-valent iron powder and increase its specific surface area and reactivity, the zero-valent iron material is modified using mechanical ball milling. Appropriate modifiers (carbonates and silicates) are added during the milling process to reduce interparticle adhesion, improve dispersibility, and prevent agglomeration. Furthermore, the milling conditions are optimized, with appropriate milling speed and time settings to reduce interparticle collision forces and lower the probability of agglomeration. Furthermore, the milling media ratio is adjusted to ensure effective abrasive collision and grinding, ensuring uniform distribution of the modifiers across the iron powder surface, thereby enhancing the modification effect.
[0019] Based on the above technical solution, preferably, in step S10, carbonate and zero-valent iron powder are added to the first ball mill according to a molar ratio of 5:100;
[0020] Silicate and zero-valent iron powder were added into the second ball mill at a molar ratio of 5:100.
[0021] Based on the above technical solution, preferably, the carbonate is sodium carbonate and the silicate is sodium silicate.
[0022] Based on the above technical solution, preferably, in step S20, the first ball mill and the second ball mill are respectively subjected to mechanical ball milling at a rotation speed of 300-800 rpm for 3-6 hours to obtain silicate-modified zero-valent iron and carbonate-modified zero-valent iron, respectively.
[0023] On the basis of the above technical solution, preferably, in step S30, silicate-modified zero-valent iron and carbonate-modified zero-valent iron are mixed in a mass ratio of 1:1 to obtain a modified zero-valent iron preparation.
[0024] The present invention also provides a water body sterilization and algae removal device, comprising a sterilization and algae removal filter unit; the filler in the sterilization and algae removal filter unit comprises the above-mentioned modified zero-valent iron preparation.
[0025] The modified zero-valent iron preparation for sterilization and algae removal in water and the preparation method thereof of the present invention have the following beneficial effects compared with the prior art:
[0026] In the present invention, zero-valent iron is modified with silicates and carbonates to produce a modified zero-valent iron preparation. This modified zero-valent iron exhibits both strong adsorption and oxygen activation for microorganisms. The synergistic effects of silicate- and carbonate-modified zero-valent iron improve the removal efficiency of contaminating microorganisms in water. Furthermore, the modified zero-valent iron preparation provided herein is simple to prepare and easy to use, and can simultaneously adsorb and inactivate both bacteria and algae, broadening the application of zero-valent iron in water purification. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0028] Figure 1 In one embodiment disclosed in the present invention, CO3 2- -ZVI bm 、SiO3 2- -ZVI bm and ZVI bm XRD results of .
[0029] Figure 2 In one embodiment disclosed in the present invention, Na2SiO3, SiO3 2- -ZVI bm and ZVI bm FTIR results of .
[0030] Figure 3 In one embodiment disclosed in the present invention, Na2CO3, CO3 2- -ZVI bm and ZVI bm FTIR results of .
[0031] Figure 4 In one embodiment disclosed in the present invention, Na2SiO3, Na2SiO3+ZVI bm 、SiO3 2- -ZVI bm and ZVI bm Plate count results for killing E. coli.
[0032] Figure 5 In one embodiment disclosed in the present invention, Na2CO3, Na2CO3+ZVI bm 、CO3 2- -ZVI bm and ZVI bm Plate count results for killing E. coli.
[0033] Figure 6 This is the E. coli fluorescence staining result of the blank control in one embodiment disclosed in the present invention.
[0034] Figure 7 In one embodiment disclosed in the present invention, ZVI bm Fluorescent staining results of E. coli after treatment.
[0035] Figure 8 In one embodiment disclosed in the present invention, SiO3 2- -ZVI bm Fluorescent staining results of E. coli after treatment.
[0036] Figure 9 In one embodiment disclosed in the present invention, CO3 2- -ZVI bm Fluorescent staining results of E. coli after treatment.
[0037] Figure 10 In one embodiment disclosed in the present invention, blank control, ZVI bm and SiO3 2- -ZVI bm ATR-FTIR detection results.
[0038] Figure 11 In one embodiment disclosed in the present invention, ZVI bm and SiO3 2- -ZVI bm The results of the zero-valent iron -OH stretching vibration peak shift before and after interaction with E. coli.
[0039] Figure 12 In one embodiment disclosed in the present invention, blank control, ZVI bm and SiO3 2- -ZVI bm The results of ultraviolet absorption signal of C=O transition after interaction with E.coli.
[0040] Figure 13 In one embodiment disclosed in the present invention, CO3 2- -ZVI bm Results of the active species quenching experiment in the system.
[0041] Figure 14 In one embodiment disclosed in the present invention, ZVI bm and CO3 2- -ZVI bm Quantitative results of superoxide radicals ( Figure 14 A) and hydroxyl radical quantitative results ( Figure 14 B).
[0042] Figure 15 In one embodiment disclosed in the present invention, ZVI bm and CO3 2- -ZVI bm The Tafel curve ( Figure 15 A) and changes in dissolved oxygen concentration ( Figure 15 B).
[0043] Figure 16 In one embodiment disclosed in the present invention, ZVI bm Infrared spectrum of E.coli after treatment ( Figure 16 A) and CO3 2- -ZVI bm Infrared spectrum of E.coli after treatment ( Figure 16 B).
[0044] Figure 17 In one embodiment disclosed in the present invention, ZVI bm Statistical results of E.coli counts after sand filter column treatment ( Figure 17 A), CO3 2- -ZVI bm E.coli count results after sand filter column treatment ( Figure 17 B), SiO3 2- -ZVI bm E.coli count results after sand filter column treatment ( Figure 17 C), E. coli count results after mixed zero-valent iron sand filter column treatment ( Figure 17 D).
[0045] Figure 18 In one embodiment disclosed in the present invention, ZVI bm Bacterial staining results after sand filter column treatment ( Figure 18 A), Bacterial staining results after treatment with mixed zero-valent iron sand filter column ( Figure 18 B).
[0046] Figure 19 In one embodiment disclosed in the present invention, ZVI bm Statistical results of bacterial counts after sand filter column treatment ( Figure 19 A), CO3 2- -ZVI bm Bacteria count results after sand filter column treatment ( Figure 19 B), SiO3 2- -ZVI bm Bacteria count results after sand filter column treatment ( Figure 19 C), bacterial count results after treatment with mixed zero-valent iron sand filter column ( Figure 19 D).
[0047] Figure 20 In one embodiment disclosed in the present invention, ZVI bm Results of removing Microcystis aeruginosa by sand filter column ( Figure 20 A), CO3 2- -ZVI bm Results of removing Microcystis aeruginosa by sand filter column ( Figure 20 B), SiO3 2- -ZVI bmResults of removing Microcystis aeruginosa by sand filter column ( Figure 20 C), the results of removing Microcystis aeruginosa by mixed zero-valent iron sand filter column ( Figure 20 D). DETAILED DESCRIPTION
[0048] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.
[0049] The term "biocide" is an agent that can eliminate bacteria and microorganisms in water.
[0050] Zero-valent iron, with its high reducibility and large specific surface area, can act as an adsorbent and reducing agent to remove harmful substances. It has a significant killing effect on Gram-negative and Gram-positive bacteria, algae, and other organisms, primarily through physical adsorption and redox reactions. However, zero-valent iron is susceptible to passivation during use and storage, resulting in a decrease in its adsorption and reduction capabilities, limiting its effectiveness.
[0051] To solve the above problems, an embodiment of the present disclosure provides a modified zero-valent iron preparation for sterilization and algae removal in water, wherein the modified zero-valent iron preparation includes silicate-modified zero-valent iron and carbonate-modified zero-valent iron; the mass ratio of the silicate-modified zero-valent iron to the carbonate-modified zero-valent iron is 1:(0.8-1.2); in the silicate-modified zero-valent iron, the molar ratio of silicate to zero-valent iron is (3-8):100; in the carbonate-modified zero-valent iron, the molar ratio of carbonate to zero-valent iron is (3-8):100.
[0052] Silicate has a strong affinity for iron and readily coordinates with iron and its oxides. Silicate modification increases the specific surface area and active sites of zero-valent iron (ZVI), enriching the surface functional groups of ZVI and increasing adsorption sites. This also enhances the adsorption interaction between ZVI and bacteria, thereby increasing the antibacterial activity of ZVI. Carbonate, with its strong electron induction capacity, can enhance the reduction activity of ZVI, promote electron transfer between the iron nucleus, and facilitate the activation of O2, generating more reactive oxygen species and enhancing the bactericidal activity of ZVI. Thus, by combining the strong adsorption capacity of silicate-modified ZVI and the excellent oxygen activation ability of carbonate-modified ZVI, the two modified ZVIs can be mass-produced into a composite filler. This effectively leverages the advantages of both, compensating for the short migration distance and self-quenching of reactive oxygen species. By combining the two modified ZVI fillers, the combined adsorption and inactivation effects of modified ZVI on microorganisms are enhanced, providing a new option for treating water contaminated by pathogenic microorganisms.
[0053] The modified zero-valent iron preparation provided by the present disclosure is further illustrated below through specific examples.
[0054] Example 1
[0055] This embodiment uses a mechanical ball milling method to prepare silicate / carbonate modified zero-valent iron, which includes the following steps:
[0056] S10. Add 4 g of commercial zero-valent iron powder and 0.379 g of sodium carbonate to a first ball mill; add 4 g of commercial zero-valent iron powder and 0.435 g of sodium silicate to a second ball mill. Both the first and second ball mills are loaded with 50 small ball mill beads with a diameter of 6 mm and 30 medium ball mill beads with a diameter of 10 mm.
[0057] S20, set the ball mill speed to 500 rpm, the time is 4 hours, and mechanical ball milling is used to obtain 5% molar ratio carbonate-modified zero-valent iron, named CO3 2- -ZVI bm , and 5% molar ratio of silicate modified zero-valent iron, named SiO3 2- -ZVI bm .
[0058] Preparation of control zero-valent iron, including the following steps:
[0059] S10. Add commercial zero-valent iron powder into a third ball milling jar, which contains 50 small ball milling beads with a diameter of 6 mm and 30 medium ball milling beads with a diameter of 10 mm.
[0060] S20, set the ball mill speed to 500 rpm, the time is 4 hours, and the unmodified zero-valent iron is obtained by mechanical ball milling, which is named ZVI bm .
[0061] X-ray powder diffraction (XRD) was used to characterize the phase structure of the samples. Figure 1 As shown, CO3 2- -ZVI bm 、SiO3 2- -ZVI bm and ZVI bm The comparison results show that silicate modification and carbonate modification do not change the original crystal structure of zero-valent iron, and the sample composition is still Fe 0 . Use infrared spectroscopy (FTIR) to characterize the functional group information on the sample surface, such as Figure 2 Shown are Na2SiO3, SiO3 2- -ZVI bm and ZVI bm Comparison results, such as Figure 3 Shown are Na2CO3, CO32- -ZVI bm and ZVI bm The results show that silicate and carbonate modify the surface of zero-valent iron, change the structure of the zero-valent iron surface oxide layer, and regulate the composition and structure of the zero-valent iron shell.
[0062] Example 2
[0063] This example compares the effect of CO3 on the removal of Escherichia coli. 2- -ZVI bm 、SiO3 2- -ZVI bm and ZVI bm Eliminate microbial activity.
[0064] ZVI bm Group: Measure 50 mL of the solution with a concentration of 1.2×10 6 CFU / mL (CFU, colony forming unit) of Escherichia coli in a conical flask, add 0.0050g (100mg / L) ZVI bm Afterwards, the conical flask was placed in a constant temperature shaker at 200 rpm and 37°C, and 5 mL of the mixed solution was taken at reaction times of 20 min, 40 min, and 60 min, and the activity effect was tested by the spread plate counting method.
[0065] CO3 2- -ZVI bm Group: Measure 50 mL of the solution with a concentration of 1.2×10 6 CFU / mL (CFU, colony forming unit) of Escherichia coli in a conical flask, add 0.0050g of CO3 with a concentration of 100mg / L 2- -ZVI bm Afterwards, the conical flask was placed in a constant temperature shaker at 200 rpm and 37°C, and 5 mL of the mixed solution was taken at reaction times of 20 min, 40 min, and 60 min, and the activity effect was tested by the spread plate counting method.
[0066] SiO3 2- -ZVI bm Group: Measure 50 mL of the solution with a concentration of 1.2×10 6 CFU / mL (CFU, colony forming unit) of Escherichia coli in a conical flask, add 0.0050g of SiO3 with a concentration of 100mg / L 2- -ZVI bm Afterwards, the conical flask was placed in a constant temperature shaker at 200 rpm and 37°C, and 5 mL of the mixed solution was taken at reaction times of 20 min, 40 min, and 60 min, and the activity effect was tested by the spread plate counting method.
[0067] Control group: 50 mL of the solution with a concentration of 1.2×10 6 CFU / mL (CFU, colony forming unit) of Escherichia coli in a conical flask, add CO3 2- -ZVI bm The same amount of Na2CO3, or add CO3 2- -ZVI bm The same amount of Na2CO3+ZVI bm After the mixture (without ball milling), the conical flask was placed in a constant temperature shaker at 200 rpm and 37°C, and 5 mL of the mixture was taken at 20 min, 40 min, and 60 min of reaction time, and the activity effect was tested by the spread plate counting method. bm The test results of the group.
[0068] Take 50mL of a solution with a concentration of 1.2×10 6 CFU / mL (CFU, colony forming unit) of Escherichia coli in a conical flask, add SiO3 2- -ZVI bm The same amount of Na2SiO3, or add SiO3 2- -ZVI bm The same amount of Na2SiO3+ZVI bm After the mixture (without ball milling), the conical flask was placed in a constant temperature shaker at 200 rpm and 37°C. 5 mL of the mixture was taken at 20 min, 40 min, and 60 min of reaction time, and the activity effect was tested by the spread plate counting method. bm The test results of the group.
[0069] See also Figure 4 , by comparing with control group and ZVI bm Group data comparison, SiO3 2- -ZVI bm The plate count results of the group showed that the addition of SiO3 2- -ZVI bm After that, the number of E. coli was significantly reduced; Figure 5 As shown, by comparing the control group and ZVI bm Group data comparison, CO3 2- -ZVI bm The plate count results of the group showed that the addition of CO3 2- -ZVI bm After that, the number of E. coli was significantly reduced. In summary, the results show that CO3 2- -ZVI bm and SiO3 2- -ZVIbm Can effectively remove E.coli (Escherichia coli). Figure 4 and Figure 5 In the table, N0 is the initial E. coli count, and N is the E. coli count at 60 min.
[0070] Example 3
[0071] This example verifies the adsorption effect of silicate-modified zero-valent iron through specific experiments.
[0072] (1) Use Live / Dead reagent to stain E. coli before and after the reaction, and observe ZVI using an inverted fluorescence microscope without eyepieces. bm 、SiO3 2- -ZVI bm The bacterial aggregation after treatment is compared to determine the strength of adsorption. Specific operations include:
[0073] A stain solution was prepared by adding 3 μL of PI (cell stain, staining dead cells and showing red) and 3 μL of SYTO9 (cell stain, staining dead and living cells and showing green) per milliliter of deionized water and mixing well.
[0074] Take ZVI in Example 2 bm Group, SiO3 2- -ZVI bm 200 μL of bacterial solution after treatment in the group and control group were added with 200 μL of staining agent, mixed, and reacted at room temperature in the dark for 20 minutes. 50 μL of the mixed solution after dyeing was placed on a slide, covered with a cover glass, and placed under an inverted fluorescence microscope without eyepieces. Turn on the fluorescent light source, find bacteria with clear vision, select a suitable area and take pictures, such as Figure 6 、 Figure 7 and Figure 8 As shown, the results show that E. coli treated with zero-valent silicate modification exhibits obvious agglomeration phenomenon, indicating that zero-valent silicate modification has strong adsorption capacity and can remove E. coli by adsorbing E. coli.
[0075] (2) Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) with diamond internal reflectance was used to characterize the interfacial interaction between zero-valent iron and E. coli. The specific operation process includes:
[0076] 1 g of ZVI prepared in Example 1 bm and 1g SiO3 2- -ZVI bm Add 1 mL of anhydrous ethanol and disperse them ultrasonically. Take the dispersed zero-valent iron suspension to the surface of the diamond crystal and dry it into a film of uniform thickness. Add 50 μL of OD670nm = 0.2 of the E. coli suspension and then start the reaction, collecting infrared spectra at preset time intervals. Figure 10 The results showed that sodium silicate-modified zero-valent iron adsorbed on bacterial proteins and caused changes in protein conformation. Silicate-modified zero-valent iron enhanced E. coli adsorption by producing chemical reactions with E. coli surface proteins.
[0077] (3) The FTIR spectra of the silicate-modified zero-valent iron before and after the reaction in Example 2 were tested to verify the interfacial hydrogen bonding.
[0078] The specific process includes: determination of ZVI using ATR-FTIR spectroscopy bm 、SiO3 2- -ZVI bm The zero-valent iron-OH stretching vibration peaks before and after the reaction with E. coli verify the interfacial hydrogen bond. Figure 11 The results show that compared with ZVI bm , silicate-modified zero-valent iron 3435cm -1 The -OH stretching vibration peak at 1632 cm -1 The -OH bending vibration peak at is slightly blue-shifted, indicating that there is an interfacial hydrogen bond between sodium silicate-modified zero-valent iron and E. coli.
[0079] (4) The FTIR spectra of the two zero-valent irons before and after the reaction and the UV-visible (UV-vis) spectra of E. coli were tested to verify the role of hydrogen bonding.
[0080] Specifically include: measuring 50mL OD 670nm = 0.2 Escherichia coli suspension in a conical flask, add 0.0050g ZVI bm and 0.0050g SiO3 2- -ZVI bm After 60 minutes of reaction, 3 mL of bacterial solution was added to a cuvette and the 800-200 nm band was scanned to obtain the absorption wavelength of the C=O transition. The untreated bacterial solution was used as a blank control. Figure 12 The results showed that the untreated E. coli showed a C=O transition UV absorption signal at 266nm. bm After the reaction, the absorption signal blue-shifted to 265nm, which is consistent with the SiO3 2- -ZVI bm After the reaction, the absorption signal blue-shifted to 260nm, indicating that SiO3 2- -ZVI bm The adsorption between E. coli can be enhanced through hydrogen bonding.
[0081] Example 4
[0082] This example verifies the bactericidal effect of carbonate-modified zero-valent iron through specific experiments.
[0083] (1) Use Live / Dead reagent to stain E. coli before and after the reaction, and observe ZVI using an inverted fluorescence microscope without eyepieces. bm 、CO3 2- -ZVI bm The damage to the bacterial membrane after treatment is compared with the intensity of oxidative damage. The specific operations include:
[0084] A stain solution was prepared by adding 3 μL of PI (cell stain, staining dead cells and showing red) and 3 μL of SYTO9 (cell stain, staining dead and living cells and showing green) per milliliter of deionized water and mixing well.
[0085] Take ZVI in Example 2 bm Group, CO3 2- -ZVI bm 200 μL of bacterial solution after treatment in the group and control group were added with 200 μL of staining agent, mixed, and reacted at room temperature in the dark for 20 minutes. 50 μL of the mixed solution after dyeing was placed on a slide, covered with a cover glass, and placed under an inverted fluorescence microscope without eyepieces. Turn on the fluorescent light source, find bacteria with clear vision, select a suitable area and take pictures, such as Figure 6 、 Figure 7 and Figure 9 As shown, the results showed that E. coli treated with zero-valent carbonate showed a significant increase in dead cells, indicating that zero-valent carbonate modification has a strong killing effect on E. coli.
[0086] (2) Quenching and quantification experiments: Superoxide dismutase (SOD), furfuryl alcohol (FFA), tert-butyl alcohol (TBA), and CAT (catalase) were used as quenchers to evaluate the main active species in the sodium carbonate-modified zero-valent iron system.
[0087] Specifically, after adding the quencher to the conical flask containing 50mL E.coli, 0.0050g ZVI was added. bm , 0.0050g CO3 2- -ZVI bm Start the reaction, take 5 mL of the mixture at 20 min, 40 min, and 60 min, and use the plate count method to count the changes in the number of bacteria after adding the quencher. The results are shown in Figure 13 The concentration of superoxide radicals in the quantitative system was detected by UV-visible spectrophotometer, and the concentration of hydroxyl radicals in the quantitative system was detected by high performance liquid chromatography. The results are as follows: Figure 14 shown. Figure 14The results show that superoxide radicals are the main active species in the carbonate-modified zero-valent iron system.
[0088] (3) Tafel curve is used to characterize the electron transfer ability and verify CO3 2- -ZVI bm Ability to activate molecular oxygen
[0089] Specifically, a three-electrode system was constructed using a calomel electrode as the reference electrode, a Pt sheet as the counter electrode, and a glassy carbon electrode with zero-valent iron powder dispersed on the surface as the working electrode to measure ZVI. bm and CO3 2- -ZVI bm The Tafel curve of the test results is as follows Figure 15 CO3 2- -ZVI bm The corrosion potential is more negative and the corrosion current is larger. The carbonate modification significantly improves the electron release and transmission capacity of ZVI, which is beneficial to the occurrence of O2 activation process.
[0090] A dissolved oxygen meter was used to monitor the concentration of dissolved oxygen in the system during the reaction. The test results were as follows: Figure 15 As shown, during the reaction, CO3 2- -ZVI bm than ZVI bm Consumes more dissolved oxygen, the results show that CO3 2- -ZVI bm It is easier to activate O2 and produce reactive oxygen species.
[0091] (4) Characterization of ZVI using attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) equipped with a diamond internal reflector bm 、CO3 2- -ZVI bm The interface interaction with E. coli, the specific operation is shown in Example 3. Figure 16 As shown in the figure, the results show that with the increase of reaction time, the 1635cm -1 and 1542cm -1 The carbonyl stretching vibration peak and amino bending vibration peak at 1240 cm-1, which belong to the cell membrane protein, have weakened, indicating that the protein on the cell membrane is damaged; -1 The antisymmetric vibration peak of the phosphodiester bond at 1086 cm -1 The peak intensity of the phosphate bond stretching vibration is significantly weakened, indicating that CO3 2- -ZVI bm It causes bacterial death by destroying the cell membrane protein and phospholipid bilayer.
[0092] Example 5
[0093] Based on the results verified in the above examples, sodium silicate modified zero-valent iron has a stronger adsorption effect on bacteria, and sodium carbonate modified zero-valent iron has a stronger oxidative damage ability on bacteria. In order to more effectively play the advantages of both, effectively couple the adsorption effect and chemical redox sterilization effect, overcome the weaknesses of short migration distance and easy self-quenching of active oxygen species, the CO3 prepared in Example 1 was added. 2- -ZVI bm , and SiO3 2- -ZVI bm Mix them in a mass ratio of 1:1 to prepare fillers and construct mixed zero-valent iron sand filter columns, ZVI bm Sand filter column, CO3 2- -ZVI bm Sand filter column, SiO3 2- -ZVI bm Sand filter column.
[0094] (1) The bacterial concentration in the effluent of the mixed zero-valent iron sand filter column was tested by plate count method to detect the performance of removing E. coli. The test results are as follows Figure 17 As shown in the figure, the mixed zero-valent iron sand filter column has better sterilization effect, longer stable operation time, and better performance in removing bacteria. Figure 17 In the figure, N in the vertical axis is the actual living cell count.
[0095] (2) The treated E. coli were stained with Live / Dead reagent, and the bacterial damage after treatment with the mixed zero-valent iron sand filter column was observed using an inverted microscope without an eyepiece. The test results are as follows: Figure 18 As shown in the figure, after being treated with the mixed zero-valent iron sand filter column, E. coli exhibited strong red fluorescence, and the mixed zero-valent iron sand filter column had a strong adsorption and inactivation ability for E. coli.
[0096] (3) Using the plate count method, the water from Wuhan East Lake was selected as the actual water sample to test the removal effect of the mixed zero-valent iron sand filter column on microorganisms in the actual water quality. The test results are as follows Figure 19 As shown in the figure, the mixed zero-valent iron sand filter column has a better effect on removing and inactivating bacteria in actual river water. Figure 19 In the figure, N in the vertical axis is the actual living cell count.
[0097] (4) The water containing Microcystis aeruginosa (algae concentration of 1×10 6 cells / mL) were subjected to ZVI bm Filter column, CO3 2- -ZVI bm Filter column, SiO3 2- -ZVI bmFilter column and mixed zero-valent iron filter column. The algae absorbance of the effluent at 680nm after different treatment times was measured by ultraviolet spectrophotometer to detect the performance of removing Microcystis aeruginosa. The test results are as follows Figure 20 As shown in the figure, the mixed zero-valent iron sand filter column also has certain advantages in capturing Microcystis aeruginosa. In addition to removing bacteria in water, the mixed zero-valent iron sand filter column can also be used to treat water contaminated by algae and has a wider range of uses.
[0098] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.
Claims
1. A modified zero-valent iron preparation for sterilization and algae removal in water, characterized in that: The invention comprises silicate-modified zero-valent iron and carbonate-modified zero-valent iron; the mass ratio of the silicate-modified zero-valent iron to the carbonate-modified zero-valent iron is 1:(0.8-1.2); In the silicate-modified zero-valent iron, the molar ratio of silicate to zero-valent iron is (3-8):100; In the carbonate-modified zero-valent iron, the molar ratio of carbonate to zero-valent iron is (3-8):
100.
2. Use of the modified zero-valent iron preparation for sterilization and algae removal in water as claimed in claim 1 in the preparation of a water microorganism removal product.
3. The use according to claim 2, wherein the water microorganism removal product comprises an adsorbent for water microorganisms.
4. The use according to claim 2, wherein the water microorganism removal product comprises a biocide for water microorganisms.
5. A method for preparing the modified zero-valent iron preparation for sterilization and algae removal in water according to claim 1, characterized in that: The following steps are involved: S10, obtaining zero-valent iron powder, carbonate, and silicate; Add carbonate and zero-valent iron powder into the first ball mill according to a molar ratio of (3-8):100; Add silicate and zero-valent iron powder into the second ball mill according to the molar ratio of (3-8):100; S20, performing mechanical ball milling in the first ball mill and the second ball mill respectively to obtain silicate-modified zero-valent iron and carbonate-modified zero-valent iron; S30. Mixing silicate-modified zero-valent iron and carbonate-modified zero-valent iron in a mass ratio of 1:(0.8-1.2) to obtain a modified zero-valent iron preparation.
6. The method for preparing the modified zero-valent iron preparation for sterilization and algae removal in water according to claim 5, characterized in that: In step S10, carbonate and zero-valent iron powder are added to a first ball mill at a molar ratio of 5:100; Silicate and zero-valent iron powder were added into the second ball mill at a molar ratio of 5:
100.
7. The method for preparing the modified zero-valent iron preparation for sterilization and algae removal in water according to claim 5 or 6, characterized in that: In step S10, the carbonate is sodium carbonate, and the silicate is sodium silicate.
8. The method for preparing the modified zero-valent iron preparation for sterilization and algae removal in water according to claim 5, characterized in that: In step S20, the first ball mill and the second ball mill are respectively subjected to mechanical ball milling at a rotation speed of 300-800 rpm for 3-6 hours to obtain silicate-modified zero-valent iron and carbonate-modified zero-valent iron, respectively.
9. The method for preparing the modified zero-valent iron preparation for sterilization and algae removal in water according to claim 5, characterized in that: In step S30, silicate-modified zero-valent iron and carbonate-modified zero-valent iron are mixed in a mass ratio of 1:1 to obtain a modified zero-valent iron preparation.
10. A water sterilization and algae removal device, characterized in that: It comprises a sterilization and algae removal filtration unit; the filler in the sterilization and algae removal filtration unit comprises the modified zero-valent iron preparation for sterilization and algae removal in water according to claim 1.