Fe-CPS complex extraction method based on dialysis bag and application of Fe-CPS complex extraction method

Abstract

The invention discloses a dialysis bag-based Fe-CPS complex extraction method and application thereof, and belongs to the technical field of water treatment and environmental protection. The method comprises the following steps: inoculating microorganisms into an inorganic salt culture medium containing water-containing iron ore, and carrying out cell disruption, centrifugation and filtration to obtain a solution containing an Fe-CPS complex; then a dialysis bag with the molecular weight cut-off of 100 Da is adopted for separation and enrichment, free iron ions and small molecular impurities can be effectively removed, and selective cut-off of the complex is achieved. The method is mild in condition and simple and convenient in flow, organic solvent extraction or solid-phase adsorption materials are not adopted in the enrichment and separation process, driving is not depended on transmembrane pressure, and the structural integrity and photochemical activity of the Fe-CPS complex can be remarkably kept. The obtained Fe-CPS complex can be used for photodegradation of steroid estrogen 17 beta-estradiol (E2) in a water body. According to the invention, stable extraction and effective application of the Fe-CPS complex are realized, and technical support is provided for related environmental research and photochemical removal of pollutants.

Description

Technical Field

[0001] This invention belongs to the field of water treatment and environmental protection technology, specifically relating to a method and application for extracting Fe-CPS complexes based on dialysis bags. Background Technology

[0002] Cell polymers (CPS) are organic matter secreted by microorganisms. In an iron-containing (Fe) environment, CPS can combine with Fe to form Fe-CPS complexes. The formation of Fe-CPS complexes may reduce the triplet excited state of CPS through electron transfer, energy transfer, or non-radiative transition processes. 3 CPS * The formation of Fe(III) can lead to the reduction of Fe(II) to Fe(III) via ligand metal charge transfer, followed by a Fenton-like reaction that generates more hydroxyl radicals (·OH), thus affecting the photodegradation of pollutants. Therefore, obtaining Fe-CPS complexes with stable binding states and well-preserved structural characteristics is an important prerequisite for further research on their photochemical behavior and environmental effects.

[0003] Currently, common methods for the extraction and enrichment of Fe-CPS complexes include solid-phase extraction, ion-exchange resin separation, and membrane separation. Solid-phase extraction achieves enrichment based on the adsorption-desorption interaction between the target component and the solid packing material. However, the adsorption / elution process may introduce disturbances to the binding state and structural characteristics, and the selection of packing material and operating conditions have a significant impact on the results. Ion-exchange resin methods rely on the exchange / adsorption between the resin's functional groups and charged components for separation. However, the selectivity for complex organometallic complexes is limited, and the separation efficiency may be affected under high ionic strength conditions. Pressure-driven membrane separation (such as nanofiltration and reverse osmosis) can achieve high separation accuracy, but it usually relies on high transmembrane pressure, resulting in high energy consumption, high operating costs, and potential interfacial shearing effects, which are not conducive to long-term stable application in some experimental systems.

[0004] In contrast, dialysis, as a membrane separation method driven by concentration gradients, does not require transmembrane pressure and has relatively mild separation conditions, which helps reduce the risk of disturbance to the binding state and structural characteristics of Fe-CPS during the separation process. However, the dialysis effect is closely related to the molecular weight cutoff of the dialysis bag and the operating conditions. Improper selection may cause the loss of target components, thereby affecting the enrichment effect.

[0005] Therefore, it is of great significance to develop an extraction method that can effectively retain Fe-CPS complexes, remove free iron ions and small molecule interfering substances, and has mild separation conditions. Summary of the Invention

[0006] The first objective of this invention is to provide a method for extracting Fe-CPS complexes based on dialysis bags. By rationally selecting the molecular weight cutoff of the dialysis bag, selective retention of Fe-CPS complexes can be achieved, removing free iron ions and small molecule interfering substances, thereby obtaining Fe-CPS complexes with good structural preservation. Furthermore, this invention expands the second objective, namely, the application of the Fe-CPS complexes in the field of organic pollutant removal.

[0007] The first objective of this invention is achieved by the following steps: (1) Purified and domesticated activated sludge bacteria, Shewan putrefactive bacteria and Escherichia coli were inoculated into an inorganic salt culture medium containing hydrated iron ore (Fhy) with sodium acetate as the sole carbon source and cultured under aerobic and anaerobic conditions respectively to obtain a culture medium. (2) The culture medium obtained in step (1) is subjected to cell disruption treatment, and after centrifugation and filtration, a mixed solution containing Fe-CPS complex is obtained, denoted as CPS + Fe; (3) The CPS + Fe solution obtained in step (2) is placed into a dialysis bag and dialyzed in ultrapure water to remove free iron ions and small molecules. After dialysis, the solution in the dialysis bag is collected to obtain the Fe-CPS complex.

[0008] Preferably, the method for preparing ferrohydrate in step (1) of the present invention is as follows: neutralize the 25.0 mM FeCl3·6H2O solution to a pH of 7.0 ± 0.1 by adding 1.0 M sodium hydroxide dropwise. Keep the obtained flocculent at 25.0 °C for 2 h, replace the supernatant with ultrapure water 6 times, and finally resuspend it with ultrapure water.

[0009] Preferably, the purification and culture of bacteria in step (1) of the present invention specifically involves: culturing bacteria from the anaerobic-anoxic-aerobic (A2-A3) culture medium obtained from the Kunming No. 7 and No. 8 water purification plants. 2 Activated sludge was obtained from the anaerobic and aerobic sections of the ( / O) process. The retrieved anaerobic and aerobic sludge were transferred in 250.0 mL portions to 500.0 mL Erlenmeyer flasks. The flasks containing anaerobic sludge were aerated with nitrogen for 25-35 min, then sealed with sealing tape and stoppers. The flasks were then placed in a constant-temperature water bath shaker for purification. The flasks containing aerobic sludge were also placed in a water bath shaker for purification. The purification and culture time for both anaerobic and aerobic bacteria was 72 h, thus obtaining strictly anaerobic and strictly aerobic activated sludge bacteria.

[0010] Preferably, the acclimatization described in step (1) of this invention is carried out using gradient concentration acclimatization. Specifically, the purified strain is poured into an expansion medium and cultured for 1 day, then acclimatized for 3 days using a medium containing different concentrations of ferrous sulfate inorganic salts (50.0, 100.0 μM), with each concentration gradient cycled 3 times. Then, 4.0 mL of a solution of 20% glycerol: bacterial solution = 3:7 is placed in a -80.0 ℃ refrigerator for later use.

[0011] Preferably, the expanded culture medium in step (1) of the present invention consists of: 10.0 g / L peptone, 5.0 g / L yeast extract, and 10.0 g / L sodium chloride. The inorganic salt culture medium used for acclimatization consists of: 1.0 g / L sodium chloride, 0.8 g / L ammonium chloride, 0.5 g / L potassium dihydrogen phosphate, 0.6 g / L dipotassium hydrogen phosphate, 0.2 g / L magnesium chloride hexahydrate, and 0.05 g / L calcium chloride dihydrate.

[0012] Preferably, in step (1) of the present invention, the purified and domesticated bacteria are inoculated into an inorganic salt culture medium containing Fhy with sodium acetate as the sole carbon source for 30 days, at a temperature of 25.0 ℃, and the concentration of ferrous sulfate is 100.0 μM.

[0013] Preferably, the cell disruption described in step (2) of this invention is performed in a high-pressure cell disruptor with a flow rate of 3.0 L / h, a motor frequency of 30.0 Hz, and a pressure of 400.0 bar. Then, a high-speed centrifuge is used to centrifuge at a speed of 12000 r / min and a temperature of 4.0 ℃ for 10 min, and the supernatant is filtered through a 0.45 μm glass fiber membrane to obtain CPS + Fe.

[0014] Preferably, the dialysis bag mentioned in step (3) of the present invention is a dialysis bag with a molecular weight cutoff of less than 500 Da.

[0015] Furthermore, the dialysis bag mentioned in step (3) of the present invention is a dialysis bag with a molecular weight cutoff of 100 Da.

[0016] Preferably, the method for treating the dialysis bag in step (3) of the present invention is as follows: cut the dialysis bag into small segments of appropriate length, boil the dialysis bag in 500.0 mL of 2% NaHCO3 aqueous solution for 10 min, and then thoroughly rinse the dialysis bag with distilled water. Next, boil the cleaned dialysis bag in 500 mL of 1.0 mM EDTA for 10 min, and then thoroughly rinse the dialysis bag with distilled water. Finally, place the dialysis bag in 500.0 mL of 50% ethanol and boil for 10 min, thoroughly rinse the dialysis bag with distilled water, cool it, and store it in a refrigerator at 4.0 ℃, ensuring that the dialysis bag is always submerged in the solution.

[0017] The second objective of this invention is achieved by applying the Fe-CPS complex prepared by the method described in this invention to the photodegradation of the steroid estrogen 17β-estradiol (E2): the Fe-CPS complex is added to water containing E2, and a photodegradation reaction is carried out under light conditions, and the active species generated during the reaction are measured.

[0018] Preferably, the dialysis in step (3) of the present invention is specifically as follows: the mixed solution obtained in step (2) is placed in a 100 Da dialysis bag, and the dialysis bag is placed in 20 times the volume of ultrapure water. The ultrapure water is replaced once at 4 h, 8 h and 12 h after the start of dialysis. After dialysis for 24 h, the liquid in the dialysis bag is collected to obtain the Fe-CPS complex.

[0019] Preferably, in the application of the Fe-CPS complex prepared by the method of the present invention in E2 photodegradation, the E2 concentration is 1.0 mg / L, the Fe-CPS complex concentration is 5.0 mgC / L, the reaction time is 180 min, and the pH is 8.0 ± 0.1.

[0020] This invention, based on the molecular weight characteristics of Fe-CPS complexes, selectively retains target components by using dialysis bags with a molecular weight cutoff of 100 Da. This allows free iron ions and small molecules to diffuse through the membrane driven by a concentration gradient, thereby achieving the separation and enrichment of Fe-CPS complexes without relying on transmembrane pressure or organic solvent extraction. The operating conditions and procedures of this invention are mild and simple, which is beneficial for obtaining Fe-CPS complexes with well-preserved structures and can be used in subsequent applications such as pollutant removal.

[0021] Compared with the prior art, the present invention has the following technical effects and advantages: (1) It is beneficial to maintain the binding state and structural characteristics of Fe-CPS complexes. The present invention uses a dialysis bag with a molecular weight cutoff of 100 Da to selectively retain Fe-CPS complexes. The enrichment and separation process does not rely on transmembrane pressure drive and does not use organic solvent extraction or strong adsorption materials for enrichment, thereby reducing the structural disturbance risk that may be caused by solid phase extraction, ion exchange or pressure-driven membrane separation.

[0022] (2) Effective removal of free iron ions and small molecule impurities while improving the retention of target components. Dialysis utilizes the concentration gradient to drive the outward diffusion of small molecules, which can effectively reduce the content of free iron ions and soluble small molecule interfering substances in the system; at the same time, under the 100 Da dialysis conditions, the retention rates of dissolved iron (DFe) and total organic carbon (TOC) are 83.3% and 43.7%, respectively, which is beneficial to maintain the target Fe-CPS component while removing interfering substances.

[0023] (3) The operating conditions are mild and the process is simple. Dialysis separation is mainly based on an aqueous system. The enrichment separation process does not rely on transmembrane pressure and does not use organic solvent extraction steps. The operation steps are relatively simple, the energy consumption and operating costs are low, and it is easy to carry out the experiment stably.

[0024] (4) Improve the photodegradation rate of pollutants. The obtained Fe-CPS complexes showed better E2 removal efficiency under light conditions than the undialyzed Fe-CPS complex mixed solution system, and generated more ·OH. Attached Figure Description

[0025] Figure 1 Figure 1 shows a comparison of the extraction effects of different molecular weight cutoff dialysis bags on Fe-CPS complexes in Examples 2, 3, Comparative Examples 2 and 3. Figure 2(a) shows the change in DFe of CPS + Fe solution (AS-Ae + Fe) produced by aerobic activated sludge before and after dialysis under molecular weight cutoff conditions of 100 Da, 500 Da and 1000 Da; Figure 3(b) shows the change in TOC of AS-Ae + Fe before dialysis under the corresponding conditions; Figure 4(c) shows the change in DFe of CPS + Fe from different microbial sources before and after dialysis under the condition of molecular weight cutoff of 100 Da; Figure 5(d) shows the change in TOC of CPS + Fe before and after dialysis under the corresponding conditions.

[0026] Figure 2 The figures show the three-dimensional fluorescence spectra of CPS, CPS + Fe, and Fe-CPS complexes in Examples 1-3 and Comparative Example 1. Figure (a) shows the three-dimensional fluorescence spectra of aerobic microorganisms; Figure (b) shows the three-dimensional fluorescence spectra of anaerobic microorganisms.

[0027] Figure 3 Figures show the changes in E2 concentration with light exposure time under aerobic (a, c, e) and anaerobic (b, d, f) conditions in different systems in Example 4. Figures (a, b) represent CPS; Figures (c, d) represent CPS + Fe; and Figures (e, f) represent Fe-CPS complexes.

[0028] Figure 4 Figure (a) shows the results of the determination of active species in the reaction system of Example 4. 3 CPS * The steady-state concentration; Figure (b) shows the singlet oxygen concentration. 1 Figure (c) shows the steady-state concentration of O2; Figure (c) shows the steady-state concentration of ·OH. Detailed Implementation

[0029] The present invention will be further described below with reference to the embodiments and accompanying drawings, but this does not limit the present invention in any way. Any changes or substitutions made based on the teachings of the present invention shall fall within the protection scope of the present invention.

[0030] Example 1 A method and application for extracting Fe-CPS complexes based on dialysis bags, comprising the following steps: (1) Purification and domestication of bacteria: The Shewanella putrefactive bacteria used in the experiment ( Shewanella BNCC186122), Escherichia coli ( Escherichia coli Both (BNCC133264) were purchased from the China Industrial Microbial Culture Collection Center. After purchase, they were revived and cultured without purification. The activated sludge bacteria were collected from the anaerobic-anoxic-aerobic (A2-A3) culture at the Kunming No. 7 and No. 8 Water Purification Plants. 2 The anaerobic and aerobic sections of the / O process. The retrieved anaerobic and aerobic sludge were transferred in 250.0 mL portions to 500.0 mL Erlenmeyer flasks. The Erlenmeyer flasks containing anaerobic sludge were aerated with nitrogen for 30 min, then sealed with sealing tape and stoppers. The Erlenmeyer flasks were then placed in a constant-temperature water bath shaker for purification. The Erlenmeyer flasks containing aerobic sludge were transferred to a water bath shaker and continuously aerated for purification. The purification and culture time for both anaerobic and aerobic bacteria was 72 h, thus obtaining strictly anaerobic and strictly aerobic activated sludge bacteria.

[0031] The above-mentioned strains were first cultured in expansion medium for 1 day, then transferred to inorganic salt medium containing Fhy for acclimatization for 3 days, and then cultured back in expansion medium for 1 day. This process was carried out at two concentration gradients of 50.0 μM and 100.0 μM, with each gradient cycled 3 times. Then, 4.0 mL of a 20% glycerol:bacterial solution ratio of 3:7 was stored at -80.0 ℃. The expansion medium contained 10.0 g / L peptone, 5.0 g / L yeast extract, and 10.0 g / L sodium chloride. The inorganic salt medium used for acclimatization contained 1.0 g / L sodium chloride, 0.8 g / L ammonium chloride, 0.5 g / L potassium dihydrogen phosphate, 0.6 g / L dipotassium hydrogen phosphate, 0.2 g / L magnesium chloride hexahydrate, and 0.05 g / L calcium chloride dihydrate. (2) Extraction of CPS + Fe: The domesticated bacteria were inoculated into an inorganic salt medium containing Fe with sodium acetate as the sole carbon source and cultured under aerobic and anaerobic conditions, respectively. After culture, the cells were disrupted, centrifuged, and filtered to obtain a solution containing Fe-CPS complex. The culture time was 30 days, the temperature was 25.0 ℃, and the concentration of ferrohydrate was 100.0 μM. The disruption was carried out in a high-pressure cell disruptor with a flow rate of 3.0 L / h, a motor frequency of 30.0 Hz, and a pressure of 400.0 bar. Then, the cells were centrifuged for 10 min at a speed of 12000 r / min and a temperature of 4.0 ℃ using a high-speed centrifuge, and the supernatant was filtered through a 0.45 μm glass fiber membrane to obtain CPS + Fe.

[0032] Comparative Example 1 The difference between this comparative example and Example 1 is that CPS are cultured without Fhy, while the other conditions are the same as in Example 1.

[0033] Example 2 A method and application for extracting Fe-CPS complexes based on dialysis bags, comprising the following steps: (1) Pretreatment of dialysis bags: Cut the dialysis bags into short segments of appropriate length. Boil the dialysis bags in 500.0 mL of 2% NaHCO3 aqueous solution for 10 min, and then thoroughly rinse the dialysis bags with distilled water. Next, boil the cleaned dialysis bags in 500.0 mL of 1.0 mM EDTA for 10 min, and then thoroughly rinse the dialysis bags with distilled water. Finally, place the dialysis bags in 500.0 mL of 50% ethanol and boil for 10 min, then thoroughly rinse the dialysis bags with distilled water. After cooling, store them in a refrigerator at 4.0 ℃, ensuring that the dialysis bags are always immersed in the solution.

[0034] (2) Extraction of Fe-CPS complexes produced by activated sludge bacteria (AS-Ae): The AS-Ae + Fe solution obtained in Example 1 was placed into a pretreated dialysis bag with a molecular weight cutoff of 100 Da. The dialysis bag was placed in ultrapure water with a volume of 20 times that of the solution inside the bag. The ultrapure water was replaced at 4 h, 8 h, and 12 h after the start of dialysis. After dialysis for 24 h, the liquid in the dialysis bag was collected to obtain the Fe-CPS complexes.

[0035] (3) The solutions before and after dialysis in step (2) were analyzed for DFe using a TAS-990 flame atomic absorption spectrometer, and the total organic carbon (TOC) was analyzed using a Vario TOC Cube analyzer. The results are as follows: Figure 1 As shown in (ab).

[0036] Comparative Example 2 The difference between this comparative example and Example 2 is that a dialysis bag with a molecular weight cutoff of 500 Da was used to dialyze AS-Ae+ Fe, while the other conditions were the same as in Example 2.

[0037] Comparative Example 3 The difference between this comparative example and Example 2 is that a dialysis bag with a molecular weight cutoff of 1000 Da was used to dialyze AS-Ae+ Fe, while the other conditions were the same as in Example 2.

[0038] Table 1. Comparison of DFe and TOC retention rates after treatment of AS-Ae + Fe with dialysis bags of different molecular weight cutoffs in Example 2, Comparative Example 2, and Comparative Example 3. Experimental Example DFe retention rate (%) TOC retention rate (%) Example 2 83.3 43.7 Comparative Example 2 59.7 7.3 Comparative Example 3 57.8 7.0 According to Table 1 and Figure 1 (ab) Data analysis shows that in Example 2, the 100 Da dialysis bag exhibits higher retention rates of DFe and TOC for AS-Ae + Fe than the 1000 Da and 500 Da dialysis bags. This indicates that while DFe is retained to some extent at larger molecular weight cutoffs (1000 Da and 500 Da), the TOC retention rate is low, making it difficult to effectively enrich Fe-CPS complexes. At a molecular weight cutoff of 100 Da, the retention rates of dissolved iron and organic carbon in the dialysis bag liquid are significantly increased, indicating that the 100 Da dialysis bag can effectively retain Fe-CPS complexes while removing small molecule dissolved salts, small molecule organic matter, and free iron ions. Therefore, 100 Da is determined to be the molecular weight cutoff for the dialysis bag used in this invention for extracting Fe-CPS complexes.

[0039] Example 3 (1) Extraction of Fe-CPS complexes: CPS + Fe solutions derived from activated sludge bacteria, Shewanella putrefactive bacteria, and Escherichia coli were dialyzed using a 100 Da dialysis bag, with other conditions the same as in Example 2, to obtain Fe-CPS complexes from different microbial sources. The results are as follows: Figure 1 (cd).

[0040] (2) Characterization of Fe-CPS complexes: The CPS + Fe, CPS, and Fe-CPS complexes obtained in Example 1, Comparative Example 1, and Example 3 were subjected to three-dimensional fluorescence spectroscopy analysis. An F-7000 fluorescence spectrophotometer was used, with a 150W xenon arc lamp as the excitation source. A PMT voltage of 700 V was applied, and the spectra were recorded using excitation and emission slits at 5 nm. The results are as follows: Figure 2 (ab).

[0041] Depend on Figure 2(ab) shows that fluorescence peaks were observed in aromatic protein I (Ex / Em = 200-250 / 280-330 nm), aromatic protein II (Ex / Em = 200-250 / 330-380 nm), and soluble microbial byproduct-like substances (Ex / Em = 250-300 / 300-380 nm). The Fe-CPS complex showed a stronger fluorescence signal in the aromatic protein region compared to undialyzed CPS + Fe. This is because dialysis removes free Fe, which can collide with the fluorophores of CPS, resulting in energy loss.

[0042] Example 4 (1) Photodegradation of E2: Under aerobic conditions, the CPS+Fe, CPS, and Fe-CPS complexes obtained in Example 1, Comparative Example 1, and Example 3 were subjected to photodegradation experiments of E2. All experiments were conducted in an XPA-7 photochemical reactor (Nanjing Xujiang Electric Machinery Factory, China) equipped with a 300 W mercury lamp and a 290 nm filter. The photodegradation of E2 (E2 = 1.0 mg / L, TOC = 5.0 mgC / L) was performed at a pH of 8.0 ± 0.1. The illumination time was 180 min, and samples were collected every 30 min. The E2 in the solution was quantified using an Agilent 1260 series high-performance liquid chromatograph (HPLC, USA). The results are as follows: Figure 3 (a, c, e).

[0043] (2) Effect of dissolved oxygen on photodegradation: The photodegradation experiment of E2 was carried out under anaerobic conditions, with the remaining conditions being the same as in step (1). The anaerobic conditions were achieved by purging with N2 for 20 min before the reaction, and the results are as follows. Figure 3 (b, d, f).

[0044] (3) Determination of active substances: Active substances were measured using a probe method, with 2,4,6-trimethylphenol (TMP, 20.0 μM), furfuryl alcohol (FFA, 20.0 μM), and p-chlorobenzoic acid (pCBA, 10.0 μM) used for determination. 3 CPS * , 1 The steady-state concentrations of O2 and ·OH were obtained as follows: Figure 4 (ac).

[0045] according to Figure 3It can be seen that, under both aerobic and anaerobic conditions, all three systems promoted the photodegradation of E2 compared to the photodegradation performance of E2 in pure water (blank control). The iron-free CPS system exhibited a higher photodegradation rate of E2 than the undialyzed CPS + Fe system, while the Fe-CPS complex showed an even higher degradation rate than CPS + Fe. Compared to aerobic conditions, the photodegradation rates of all three systems were increased under anaerobic conditions.

[0046] according to Figure 4 It can be seen that under illumination, the following three systems can generate [the substance / property]. 3 CPS * , 1 O2 and ·OH, but the steady-state concentrations of various active substances differ significantly in different systems, and Fe-CPS complexes can generate more ·OH.

[0047] In summary, this invention provides a method for extracting Fe-CPS complexes based on dialysis bags. By rationally selecting the molecular weight cutoff of the dialysis bag under mild conditions, the effective separation and enrichment of Fe-CPS complexes are achieved. This method can effectively remove free iron ions and small molecule interfering substances from the system, which is beneficial for maintaining the binding state and structural characteristics of Fe-CPS complexes and improving their structural stability and reproducibility. Furthermore, the obtained Fe-CPS complexes were used for the photodegradation of steroid estrogen E2 in water. The results showed that under light conditions, it can promote the generation of ·OH, thereby improving the removal efficiency of pollutants.

Claims

1. A method for extracting Fe-CPS complexes based on dialysis bags, characterized in that, Includes the following steps: (1) Purified and domesticated activated sludge bacteria, Shewan putrefactive bacteria and Escherichia coli were inoculated into an inorganic salt culture medium containing water iron ore with sodium acetate as the sole carbon source and cultured under aerobic and anaerobic conditions respectively to obtain a culture medium. (2) The culture medium obtained in step (1) is subjected to cell disruption treatment, and after centrifugation and filtration, a mixed solution containing Fe-CPS complex is obtained; (3) The mixed solution obtained in step (2) is placed into a dialysis bag and dialyzed in ultrapure water to remove free iron ions and small molecules; after dialysis, the solution in the dialysis bag is collected to obtain Fe-CPS complex.

2. The method for extracting Fe-CPS complexes based on dialysis bags according to claim 1, characterized in that, The preparation method of ferrohydrate in step (1) is as follows: neutralize the 25.0 mM FeCl3·6H2O solution to pH 7.0 ± 0.1 by adding 1.0 M NaOH dropwise; keep the obtained flocculent at 25.0 ℃ for 2 h, replace the supernatant with ultrapure water 6 times, and finally resuspend it with ultrapure water.

3. The method for extracting Fe-CPS complexes based on dialysis bags according to claim 1, characterized in that, The specific purification and culture of bacteria in step (1) is as follows: Activated sludge is obtained from the anaerobic and aerobic parts of the anaerobic-anoxic-aerobic process. The retrieved anaerobic sludge and aerobic sludge are transferred to a conical flask. The conical flask containing anaerobic sludge is aerated with nitrogen gas for 25-35 minutes and then sealed. The conical flask is then placed in a constant temperature water bath shaker for purification. The conical flask containing aerobic sludge was transferred to a water bath shaker for continuous aeration and purification. The purification and culture time for both anaerobic and aerobic bacteria was 72 h, thus obtaining strictly anaerobic and strictly aerobic activated sludge bacteria.

4. The method for extracting Fe-CPS complexes based on dialysis bags according to claim 1, characterized in that, In step (1), the acclimatization is carried out by gradient concentration acclimatization. Specifically, the purified strain is poured into the expansion medium and cultured for 1 day. Then, it is acclimatized for 3 days with water iron mineral inorganic salt medium containing 50.0 μM and 100.0 μM respectively. Each concentration gradient is cycled 3 times. Then, it is stored in a -80.0 ℃ refrigerator with 20% glycerol: bacterial solution = 3:7 for later use.

5. The method for extracting Fe-CPS complexes based on dialysis bags according to claim 4, characterized in that, The expansion culture medium described in step (1) contains 10.0 g / L peptone, 5.0 g / L yeast extract, and 10.0 g / L sodium chloride. The inorganic salt culture medium used for acclimatization contains 1.0 g / L sodium chloride, 0.8 g / L ammonium chloride, 0.5 g / L potassium dihydrogen phosphate, 0.6 g / L dipotassium hydrogen phosphate, 0.2 g / L magnesium chloride hexahydrate, and 0.05 g / L calcium chloride dihydrate.

6. The method for extracting Fe-CPS complexes based on dialysis bags according to claim 1, characterized in that, In step (1), the purified and domesticated bacteria are inoculated into an inorganic salt culture medium containing ferrohydrate with sodium acetate as the sole carbon source and cultured for 30 days at a temperature of 25.0 °C and a ferrohydrate concentration of 100.0 μM.

7. The method for extracting Fe-CPS complexes based on dialysis bags according to claim 1, characterized in that, The cell disruption described in step (2) was performed in a high-pressure cell disruptor with a flow rate of 3.0 L / h, a motor frequency of 30.0 Hz, and a pressure of 400.0 bar. Then, a high-speed centrifuge was used to centrifuge the solution for 10 min at a speed of 12000 r / min and a temperature of 4.0 ℃. The supernatant was filtered through a 0.45 μm glass fiber membrane to obtain a mixed solution containing Fe-CPS complex.

8. The method for extracting Fe-CPS complexes based on dialysis bags according to claim 1, characterized in that, The dialysis bag mentioned in step (3) needs to be pretreated as follows: cut the dialysis bag into small segments of appropriate length, boil the dialysis bag in 2% NaHCO3 aqueous solution for 5-15 min and then thoroughly rinse the dialysis bag with distilled water; then boil the cleaned dialysis bag in 1.0 mM EDTA for 5-15 min and then thoroughly rinse the dialysis bag with distilled water; finally, place the dialysis bag in 50% ethanol and boil for 5-15 min, thoroughly rinse the dialysis bag with distilled water, cool it and store it in a refrigerator at 4.0 ℃, and keep the dialysis bag submerged in the solution at all times.

9. The method for extracting Fe-CPS complexes based on dialysis bags according to claim 1, characterized in that, The dialysis in step (3) is as follows: the mixed solution obtained in step (2) is placed in a dialysis bag with a molecular weight cutoff of 100 Da, and the dialysis bag is placed in 20 times the volume of ultrapure water. The ultrapure water is replaced once at 4 h, 8 h and 12 h after the start of dialysis. After dialysis for 24 h, the liquid in the dialysis bag is collected to obtain the Fe-CPS complex.

10. The application of an Fe-CPS complex prepared by any one of claims 1-9 in the photodegradation of the steroid estrogen 17β-estradiol.

Images