A zeolite / zero-valent iron and a zeolite / zero-valent iron-microorganism composite adsorbent and their applications

Abstract

This invention relates to the field of adsorbent technology, specifically to a zeolite / zero-valent iron (ZVFe) and a zeolite / ZVFe-microorganism composite adsorbent and their applications. The zeolite / ZVFe is prepared by the following steps: S1, mixing FeCl3 solution with zeolite and adjusting the pH to 3-4 using an alkaline solution to obtain a first mixed solution; S2, mixing the first mixed solution under ultrasonic conditions; S3, continuing stirring with a mechanical stirrer while gradually adding NaBH4 solution dropwise, and continuing stirring after the addition is complete to obtain a second mixed solution; S4, separating the second mixed solution into solid and liquid phases to obtain a black solid powder, which is then washed and freeze-dried to obtain the zeolite / ZVFe. This zeolite / ZVFe effectively prevents the aggregation and oxidation of ZVFe.

Description

Technical Field

[0001] This invention relates to the field of adsorbent technology, specifically to a zeolite / zero-valent iron and a zeolite / zero-valent iron-microorganism composite adsorbent and their applications. Background Technology

[0002] Organophosphate flame retardants (OPFRs) are flame-retardant materials widely used in industrial production, with chlorinated organophosphate flame retardants being the most prevalent. Currently, the use of OPFRs is primarily through physical addition, leading to a high risk of leakage as equipment wears down and usage time increases. Furthermore, existing wastewater treatment technologies cannot completely remove OPFRs from water bodies, resulting in their entry into the environment. Studies have also shown that OPFRs possess biotoxicity, including neurotoxicity, reproductive toxicity, immunotoxicity, and genotoxicity. Therefore, effective removal of OPFRs from the environment is urgently needed. Current removal methods for OPFRs mainly include physical adsorption, chemical degradation, and biodegradation. Although numerous studies have demonstrated the high efficiency of these technologies in removing OPFRs from the environment, certain limitations remain in practical applications.

[0003] Physical adsorption only adsorbs organophosphorus flame retardants into the adsorbent, but does not degrade the adsorbed harmful substances. After adsorbing pollutants, secondary treatment is required to achieve complete degradation and mineralization.

[0004] Chemical degradation technology can overcome the limitations of physical adsorption technology in degrading minerals by adding chemical reagents. However, chemical degradation requires the addition of large amounts of chemical reagents, resulting in high treatment costs. Furthermore, the addition of large amounts of chemical reagents can easily cause secondary pollution, further increasing treatment costs and difficulty.

[0005] Although biotechnology can render the removal process of organophosphorus flame retardants harmless, it has shortcomings such as low degradation efficiency and low degradation rate during application.

[0006] Currently, zero-valent iron (ZVI), as an emerging adsorbent material, possesses excellent adsorption capacity due to its unique core-shell structure, and has gradually become a research hotspot for scholars both domestically and internationally in recent years. Furthermore, because iron itself is a relatively reactive metallic element, it also possesses a certain degradation and mineralization ability during the removal of organic pollutants, making zero-valent iron superior to traditional adsorbents in the application of organic pollutant treatment.

[0007] However, zero-valent iron also has its shortcomings as an adsorbent material: as a metallic component, zero-valent iron is relatively heavy and tends to clump together, affecting its adsorption effect and failing to achieve a good adsorption effect. As a result, zero-valent iron has limited ability to degrade organic pollutants and cannot completely degrade and mineralize recalcitrant organic pollutants. This may lead to the generation of more toxic intermediate products during the treatment process, increasing the risk of secondary pollution. Summary of the Invention

[0008] One of the objectives of this invention is to overcome the shortcomings of the prior art by providing a zeolite / zero-valent iron solution that allows iron ions to be effectively dispersed and loaded on the zeolite, avoiding the problem of easy aggregation when using only zero-valent iron as an adsorbent.

[0009] The second objective of this invention is to provide a zeolite / zero-valent iron-microorganism composite adsorbent that combines the properties of physical adsorption, chemical degradation, and biodegradation, and has the advantages of being environmentally friendly, low-cost, and having high adsorption efficiency.

[0010] The third objective of this invention is to provide an application of a zeolite / zero-valent iron-microorganism composite adsorbent.

[0011] To achieve one of the above objectives, the present invention provides the following technical solution:

[0012] A zeolite / zero-valent iron is provided, which is prepared by the following method, the preparation method comprising the following steps:

[0013] S1. Mix FeCl3 solution with zeolite, and adjust the pH to 3-4 using alkaline solution to obtain the first mixed solution;

[0014] S2. Mix the first mixed solution under ultrasonic conditions;

[0015] S3. Continue stirring with a mechanical stirrer while gradually adding NaBH4 solution dropwise. After the addition is complete, continue stirring to obtain the second mixed solution.

[0016] S4. The second mixed solution is separated into solid and liquid components to obtain a black solid powder. The black solid powder is then washed and freeze-dried to obtain zeolite / zero-valent iron.

[0017] In some embodiments, in step S1, the concentration of the FeCl3 solution is 0.15–0.25 mol / L;

[0018] The mass ratio of the FeCl3 solution to the zeolite is 3-4:1;

[0019] The alkaline solution is a NaOH solution with a concentration of 0.5–1.5 mol / L.

[0020] In some embodiments, in step S2, the frequency of the ultrasound is 80-100 Hz, the mixing temperature is 25-35°C, and the mixing time is 10-20 min.

[0021] In some embodiments, in step S3, the concentration of the NaBH4 solution is 0.5–1 mol / L, and the dropping rate is 1–3 mL / s.

[0022] In some embodiments, step S4, the step of solid-liquid separation of the second mixed solution, includes:

[0023] Let the solution stand for 4–6 minutes, then filter it.

[0024] The washing steps include: first washing the black solid powder with deionized water 2 to 4 times, and then washing the black solid powder with anhydrous ethanol 2 to 4 times.

[0025] The beneficial effects of this invention on zeolite / zero-valent iron:

[0026] The zeolite / zero-valent iron of this invention uses FeCl3 as the iron source for zero-valent iron. FeCl3 can be loaded onto the zeolite surface in a dispersed manner. After FeCl3 is dispersed on the zeolite surface, it is reduced to zero-valent iron by NaBH4 at a suitable pH, so that zero-valent iron can be stably and uniformly distributed on the zeolite. Since zero-valent iron is first loaded onto the zeolite in the form of FeCl3 solution, it can be uniformly distributed on the zeolite without affecting the function of the zeolite. The uniform and stable dispersion of zero-valent iron on the zeolite avoids the problem of zero-valent iron aggregation. At the same time, the zeolite can also play a good role in removing pollutants.

[0027] To achieve the second objective mentioned above, the present invention provides the following technical solution:

[0028] A zeolite / zero-valent iron-microorganism composite adsorbent is provided, which is prepared by the following method, the preparation method comprising the following steps:

[0029] S21. Add the bacterial suspension and the zeolite / zero-valent iron described in any one of claims 1 to 5 into a container and mix them evenly. The bacterial cells in the bacterial suspension are functional microorganisms.

[0030] S22. Seal the container with sealing film, place the container on a shaker, and load the bacterial cells in the bacterial suspension onto zeolite / zero-valent iron to obtain a loaded mixture;

[0031] S23. Take out the loaded mixture, filter the loaded mixture to obtain solid powder, freeze-dry the solid powder and store it at -4 to -3°C for later use.

[0032] In some embodiments, step S21, the method for preparing the bacterial suspension includes:

[0033] Add the bacterial seed culture to sterile nutrient medium, then culture it in a shaker at 25-35°C for 22-24 hours. Remove the culture, centrifuge, collect all the bacterial cells, wash them with sterile water, and then prepare a bacterial suspension with sterile water.

[0034] In some embodiments, the bacterial seed culture is *Sphingomonas neosphingolipidae*, denoted as N1.

[0035] In some embodiments, the mass ratio of the bacterial suspension to the zeolite / zero-valent iron is 2-2.5:1-1.5;

[0036] The concentration of the bacterial suspension is 100–120 g / L.

[0037] The beneficial effects of the zeolite / zero-valent iron-microorganism composite adsorbent of this invention are as follows:

[0038] The zeolite / zero-valent iron-microorganism composite adsorbent of the present invention uses zeolite / zero-valent iron as the adsorbent. Zero-valent iron is uniformly and stably dispersed on the zeolite, avoiding aggregation of zero-valent iron and ensuring the pollutant removal performance of zeolite / zero-valent iron. At the same time, microorganisms are loaded on the zeolite / zero-valent iron, which can decompose the pollutants adsorbed by zeolite / zero-valent iron, achieving the purpose of thorough mineralization and avoiding the risk of secondary pollution.

[0039] The invention also provides an application of the above-mentioned zeolite / zero-valent iron-microorganism composite adsorbent, specifically its application in the removal of organophosphorus flame retardants, sulfonamide antibiotics, or metal ions from water. Attached Figure Description

[0040] Figure 1 The removal rate of TCEP (tris(2-chloroethyl) phosphate) by the zeolite / zero-valent iron-microbial composite adsorbent (Z / ZVI-microbial composite adsorbent) in a specific embodiment of the present invention is shown.

[0041] Figure 2 This is a finished product image of the zeolite / zero-valent iron-microorganism composite adsorbent according to a specific embodiment of the present invention.

[0042] Figure 3 This is a time-varying graph showing the TCEP removal rate of the zeolite / zero-valent iron-microorganism composite adsorbent according to a specific embodiment of the present invention.

[0043] Figure 4 This refers to the removal rate of TCEP at different concentrations by the zeolite / zero-valent iron-microorganism composite adsorbent according to a specific embodiment of the present invention.

[0044] Figure 5 The removal rate of TCEP by the zeolite / zero-valent iron-microorganism composite adsorbent in a specific embodiment of the present invention at different pH values ​​is shown.

[0045] Figure 6 The removal rate of three sulfonamide antibiotics by the zeolite / zero-valent iron-microorganism composite adsorbent according to a specific embodiment of the present invention.

[0046] Figure 7 The removal rate of six heavy metal ions by the zeolite / zero-valent iron-microorganism composite adsorbent according to a specific embodiment of the present invention. Detailed Implementation

[0047] Preferred embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While preferred embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0048] Example 1

[0049] To illustrate how to obtain zero-valent iron that is not easily aggregated and oxidized, this embodiment discloses a zeolite / zero-valent iron (Z / ZVI) prepared by the following method, which includes the following steps:

[0050] S1. Mix FeCl3 solution with zeolite, and adjust the pH to 3-4 using alkaline solution to obtain the first mixed solution;

[0051] The above steps allow the FeCl3 solution to be initially mixed with the zeolite, enabling the FeCl3 solution to react with the zeolite initially, resulting in a pH of 3-4, which facilitates a slightly acidic solution.

[0052] S2. Mix the first mixed solution under ultrasonic conditions.

[0053] The above-mentioned ultrasonic conditions can accelerate the contact efficiency between the FeCl3 solution and the zeolite in the first mixed solution.

[0054] S3. Continue stirring with a mechanical stirrer while gradually adding NaBH4 solution dropwise. After the addition is complete, continue stirring to obtain the second mixed solution.

[0055] The purpose of adding NaBH4 solution is to reduce FeCl3, so that FeCl3 loaded on the zeolite can be converted into zero-valent iron, thereby achieving the removal efficiency of zero-valent iron.

[0056] S4. The second mixed solution is separated into solid and liquid components to obtain a black solid powder. The black solid powder is then washed and freeze-dried to obtain zeolite / zero-valent iron.

[0057] After solid-liquid separation of the second mixed solution through the above steps, a black solid powder is obtained, which is zeolite / zero-valent iron loaded with iron ions. Washing and freeze-drying the black solid powder to remove impurities yields a purer zeolite / zero-valent iron.

[0058] In this embodiment, in step S1, the concentration of the FeCl3 solution is 0.15–0.25 mol / L, preferably 0.24 mol / L.

[0059] The mass ratio of the FeCl3 solution to the zeolite is 3 to 4:1, preferably 3:1;

[0060] The alkaline solution is a NaOH solution with a concentration of 0.5–1.5 mol / L, preferably 1 mol / L.

[0061] In this embodiment, in step S2, the frequency of the ultrasound is 80-100Hz, preferably 90Hz, the mixing temperature is 25-35℃, preferably 30℃, and the mixing time is 10-20min, preferably 15min.

[0062] In this embodiment, in step S3, the concentration of the NaBH4 solution is 0.5–1 mol / L, preferably 0.96 mol / L, and the dropping rate is 1–3 mL / s, preferably 2 mL / s.

[0063] In this embodiment, step S4, the step of separating the solid and liquid components of the second mixed solution, includes:

[0064] Let the solution stand for 4 to 6 minutes, preferably 5 minutes, and then filter it.

[0065] The washing steps include: first washing the black solid powder with deionized water 2 to 4 times, preferably 3 times, and then washing the black solid powder with anhydrous ethanol 2 to 4 times, preferably 3 times.

[0066] Example 2

[0067] To illustrate how to prepare a zeolite / zero-valent iron-microorganism composite adsorbent (Z / ZVI-microorganism composite adsorbent), this embodiment discloses a zeolite / zero-valent iron-microorganism composite adsorbent prepared by the following method, which includes the following steps:

[0068] S21. Add the bacterial suspension of the formula amount and the zeolite / zero-valent iron of Example 1 into a container and mix them evenly. The bacterial cells in the bacterial suspension are functional microorganisms.

[0069] The above steps allow the bacterial suspension to be initially mixed with zeolite / zero-valent iron.

[0070] S22. Seal the container with sealing film, place the container on a shaker, and load the bacterial cells in the bacterial suspension onto zeolite / zero-valent iron to obtain a loaded mixture;

[0071] The above steps involve cultivating the bacterial suspension on a shaker to load it onto zeolite / zero-valent iron.

[0072] S23. Take out the loaded mixture, filter the loaded mixture to obtain solid powder, freeze-dry the solid powder and store it at -4 to -3°C for later use.

[0073] The above steps separate zeolite / zero-valent iron loaded with bacteria.

[0074] In this embodiment, step S21, the method for preparing the bacterial suspension includes:

[0075] The bacterial seed culture is added to a sterile nutrient medium, wherein the liquid volume percentage of the bacterial seed is 1%. In practical applications, the amount of bacterial seed can be adjusted according to actual needs. Then, it is cultured in a shaker at 25-35°C, preferably 30°C, and 160 rpm for 22-24 hours. After that, it is taken out, centrifuged, and all bacterial cells are collected. The cells are first washed with sterile water and then prepared into a bacterial suspension with sterile water.

[0076] In this embodiment, the bacterial seed culture is *Novosphingobium tardaugens*, i.e., N1 strain.

[0077] In this embodiment, the mass ratio of the bacterial suspension to the zeolite / zero-valent iron (M) 菌 :M 沸石 / 零价铁 The ratio is 2 to 2.5:1 to 1.5, preferably 2:1;

[0078] In this embodiment, the concentration of the bacterial suspension is 100-120 g / L, preferably 100 g / L.

[0079] The above-mentioned zeolite / zero-valent iron-microorganism composite adsorbent is used in the removal of organophosphorus flame retardants, sulfonamide antibiotics, or metal ions from water. In practical applications, the types of organophosphorus flame retardants, sulfonamide antibiotics, or metal ions can be selected according to the specific circumstances.

[0080] Effect test:

[0081] The zeolite / zero-valent iron-microorganism composite adsorbent was prepared through the following specific experimental examples, including:

[0082] Preparation of bacterial suspension

[0083] The seed culture of Novosphingobium tardaugens was added to sterilized nutrient medium at an inoculation rate of 1% (V / V), and then cultured in a shaker at 30°C and 160 rpm for 22–24 h. The culture was then removed, centrifuged at 7000 rpm and 25°C for 5 min, and all bacterial cells were collected. The cells were washed twice with sterile water (7000 rpm, 5 min), and finally prepared into a 100 g / L bacterial suspension with sterile water for later use.

[0084] Preparation of zeolite / zero-valent iron

[0085] The specific steps for preparing zeolite / zero-valent iron are as follows: 0.24 mol / L FeCl3 solution is mixed with natural zeolite at a mass ratio (M... 沸石 M Fe The solutions were mixed in a 3:1 ratio (FeCl3:FeCl3), and the pH was adjusted to 3-4 with 1 mol / L NaOH. The mixture was then sonicated at 90 Hz and 30°C for 15 min. After mixing, the solution was stirred at 800 rpm using a mechanical stirrer, while a 0.96 mol / L NaBH4 solution (equal volume to the FeCl3 solution) was slowly added at a dropping rate of 2 mL / s. Stirring continued for 1 h after the addition was complete to ensure a complete reaction. The solution was then allowed to stand for 5 min, filtered, and the black solid powder was separated. The powder was washed three times with deionized water and three times with anhydrous ethanol, and finally lyophilized to obtain Z / ZVI.

[0086] Preparation of zeolite / zero-valent iron-N1 (Z / ZVI-N1)

[0087] Z / ZVI-N1 was prepared using a direct mixing and loading method. The specific steps were as follows: the prepared bacterial suspension was mixed at a certain mass ratio (M... 菌 :M Z / ZVI =2:1) ​​mixed with Z / ZVI, the bottle mouth was sealed with sealing film, and the mixture was loaded in a shaker at 30℃ and 160rpm for a certain period of time. Immediately after loading, it was removed and separated by vacuum filtration. Figure 2As shown, a solid powder was obtained, which was then freeze-dried and stored at -4°C for later use.

[0088] Perform the following tests:

[0089] 1. Removal rate of TCEP by different adsorbent materials

[0090] This study investigated the removal efficiency of *Novosphingobium tardaugens* (N1 bacteria), zeolite, zeolite and N1 bacteria (i.e., a direct mixture of zeolite and N1 bacteria), zeolite / zero-valent iron, and zeolite / zero-valent iron-N1 composite adsorbent on TCEP. The specific implementation scheme is as follows: The reaction system consisted of 20 mL of sterile water (with 20 mL of phosphorus-free inorganic salt culture medium as the microbial degradation system), and TCEP standard solution was added. The concentration of TCEP was 1 mg / L. The addition amounts of *Novosphingobium tardaugens* (N1 bacteria), zeolite, zeolite and N1 bacteria, zeolite / zero-valent iron, and zeolite / zero-valent iron-N1 composite adsorbent were 1 g each. The microbial concentration in the system was 1 g / L. The reaction conditions were 160 rpm, 30 °C, and the sampling time was 24 h.

[0091] Depend on Figure 1 Therefore, the specific conclusions are as follows:

[0092] The removal rates, ranked from highest to lowest, are: zeolite / zero-valent iron-N1 composite adsorbent (Z / ZVI-N1) > zeolite / zero-valent iron (Z / ZVI) > zero-valent iron powder > N1 bacteria > mixture of zeolite powder and N1 bacteria (zeolite, N1). Zeolite / zero-valent iron has an anti-aggregation effect; by loading the bacteria onto the zeolite / zero-valent iron, the bacteria's influence on the zeolite / zero-valent iron is avoided. Simply mixing zeolite powder and bacteria results in the bacteria filling the adsorption pores of the zeolite powder, reducing its removal efficiency. Furthermore, the growth of N1 bacteria is inhibited by the zeolite. Conversely, using N1 bacteria alone yields a higher removal efficiency than using N1 with zeolite. Therefore, the zeolite / zero-valent iron-N1 composite adsorbent prepared by this invention exhibits a synergistic effect.

[0093] In summary, the zeolite / zero-valent iron-N1 composite adsorbent can achieve more efficient adsorption-degradation removal of TCEP.

[0094] 2. Changes in TCEP removal rate over time using zeolite / zero-valent iron-N1

[0095] This study investigated the removal rate of TCEP by zeolite / zero-valent iron-N1 composite adsorbent (Z / ZVI-N1) over time. The specific implementation plan is as follows: The reaction system consisted of 20 mL of sterile water, with a certain amount of TCEP standard solution added to make the TCEP concentration in the system 1 mg / L. The amount of zeolite / zero-valent iron-N1 added was 1 g. The reaction conditions were 160 rpm and 30 °C. The sampling times were 2, 4, 8, 12, 24, 36, and 48 h.

[0096] according to Figure 3 The removal rate of TCEP by the zeolite / zero-valent iron-N1 composite adsorbent over time was examined. The removal rate peaked at 8 hours (74.3%), then decreased after 24 hours, stabilizing at 69.2% after 36 hours. Compared to traditional microbial techniques, the zeolite / zero-valent iron-N1 composite adsorbent showed a significant improvement, indicating that it can better enhance the removal rate of TCEP.

[0097] 3. Removal of TCEP from different initial concentrations by zeolite / zero-valent iron-N1

[0098] This study investigated the removal efficiency of zeolite / zero-valent iron-N1 composite adsorbent (Z / ZVI-N1) for TCEP at different initial concentrations. The specific implementation plan is as follows: The reaction system consisted of 20 mL of sterile water, with a certain amount of TCEP standard solution added to achieve TCEP concentrations of 0.5, 1, 2, 3, 4, and 5 mg / L. The amount of zeolite / zero-valent iron-N1 composite adsorbent added was 1 g. The reaction conditions were 160 rpm, 30 °C, and a reaction time of 48 h.

[0099] according to Figure 4 The study investigated the removal efficiency of the zeolite / zero-valent iron-N1 composite adsorbent for TCEP at different initial concentrations. The specific conclusions are as follows: Z / ZVI-N1 showed a removal effect on TCEP-contaminated water with concentrations ranging from 0.5 to 5 mg / L, with the removal rate generally around 50%.

[0100] Therefore, Z / ZVI-N1 has a good ability to treat polluted water with TCEP concentrations of 0.5–5 mg / L.

[0101] 4. Factors affecting the adsorption of TCEP by zeolite / zero-valent iron-N1

[0102] This study investigated the effects of reaction temperature and pH on the removal of TCEP by the zeolite / zero-valent iron-N1 composite adsorbent (Z / ZVI-N1). The specific implementation scheme is as follows: The reaction system consisted of 20 mL of sterile water. The pH of the reaction system was adjusted to 5, 7, and 9 using 10% H2SO4 (V / V) and 10% NaOH (V / V) solutions, respectively. The reaction conditions were 160 rpm and 30℃. For the temperature effect experiment, the reaction temperatures were set at 25℃, 30℃, and 35℃, and the reaction conditions were pH = 7 and 160 rpm. The initial TCEP concentration was 1 mg / L, and the amount of zeolite / zero-valent iron-N1 composite adsorbent added was 1 g. Sampling times were 2, 4, 8, 12, 24, 36, and 48 h.

[0103] The removal rate of TCEP by the zeolite / zero-valent iron-N1 composite adsorbent under different temperature conditions was investigated. The specific conclusions are as follows: At 25℃ and 30℃, the removal rate of TCEP by Z / ZVI-N1 increased rapidly within 0–24 h and decreased slowly within 24–48 h; while at 35℃, the TCEP removal rate continued to increase with the reaction, reaching adsorption equilibrium at 36 h. The TCEP removal rate reached its peak fastest at 30℃, followed by 25℃ (24 h), and took the longest at 35℃ (36 h). Furthermore, the peak removal rates of TCEP were similar at different temperatures, indicating that temperature has a relatively small effect on the TCEP removal capacity of Z / ZVI-N1, only affecting the reaction rate.

[0104] In summary, the optimal temperature for Z / ZVI-N1 to remove TCEP is 30℃.

[0105] according to Figure 5 The removal rate of TCEP by the zeolite / zero-valent iron-N1 composite adsorbent was investigated under different reaction pH conditions. At pH=7, the Z / ZVI-N1 adsorbent showed the fastest removal rate of TCEP, reaching the maximum removal rate in 24 hours, and also exhibited the highest TCEP removal rate (over 70%) compared to other pH conditions.

[0106] In summary, Z / ZVI-N1 is suitable for use under neutral pH conditions.

[0107] 5. Removal of three sulfonamide antibiotics by zeolite / zero-valent iron-N1

[0108] To investigate the removal capacity of zeolite / zero-valent iron-N1 composite adsorbent (Z / ZVI-N1) for other organic pollutants, this scheme examined the removal efficiency of zeolite / zero-valent iron-N1 composite adsorbent for three sulfonamide antibiotics (sulfamerazine (SMZ), sulfamethoxazole (SMX), and sulfadiazine (SZ)). The specific implementation scheme is as follows: The reaction system was set as 20 mL of sterile water, and antibiotic standard solutions were added to make the concentration of each antibiotic in the system reach 1 mg / L. The amount of zeolite / zero-valent iron-N1 added was 1 g. The reaction conditions were 160 rpm and 30 °C. The sampling times were 2, 4, 8, 12, 24, 36, and 48 h.

[0109] according to Figure 6 This invention also investigated the removal efficiency of the zeolite / zero-valent iron-N1 composite adsorbent for three common sulfonamide antibiotics in the environment: SMZ, SMX, and SZ. Within 48 hours of the reaction, the removal rate of SMX by Z / ZVI-N1 gradually increased, reaching 43.8% at 48 hours; the removal rate of SZ was relatively stable in the first 24 hours, gradually increasing from 24 to 48 hours, eventually reaching 48.6%; the removal rate of SMZ showed an increasing trend in the first 24 hours after the start of the reaction, reaching its maximum value (35.7%) at 24 hours.

[0110] In summary, the zeolite / zero-valent iron-N1 composite adsorbent also showed good removal efficiency for three common sulfonamide antibiotics in the environment, indicating that zeolite / zero-valent iron-N1 has the potential to treat other organic pollutants.

[0111] 6. Removal rate of 6 heavy metal ions by zeolite / zero-valent iron-N1

[0112] To investigate the removal capacity of the zeolite / zero-valent iron-N1 composite adsorbent (Z / ZVI-N1) for other types of pollutants, this scheme also examined the removal capacity of the zeolite / zero-valent iron-N1 composite adsorbent for six heavy metal ions (Cu). 2+ Cr 6+ Cd 2+ Pb 2+ Ni 2+ And As 3+ The treatment effect of the complex pollution system is illustrated by the following implementation plan: The reaction system consists of 20 mL of sterile water, with the addition of six heavy metal standard solutions to increase the Cu content in the system. 2+ The concentration was 10 mg / L, Cd 2+ The concentration was 0.2 mg / L, Ni 2+ The concentration of Pb is 1 mg / L. 2+ As3+ and Cr 6+ The concentration of each adsorbent was 2 mg / L, the amount of zeolite / zero-valent iron-N1 composite adsorbent added was 1 g, the reaction conditions were 160 rpm and 30 °C, and the sampling times were 2, 4, 8, 12, 24, 36 and 48 h.

[0113] according to Figure 7 This invention also investigated the effects on six common heavy metal ions in the environment: Cu 2+ Cr 6+ Cd 2+ Pb 2+ Ni 2+ And As 3+ The removal effect of Z / ZVI-N1 was observed at 2 hours after the start of the reaction, showing significant improvement in Ni removal efficiency. 2+ The removal rate of heavy metal ions, in addition to Ni, also reached over 99%, and Ni... 2+ The removal rate also reached over 99% by the 12th hour of the reaction; in addition, no heavy metal desorption was observed in Z / ZVI-N1 within 48 hours of the reaction.

[0114] In summary, the zeolite / zero-valent iron-N1 composite adsorbent can not only be used to remove organic pollutants from the environment, but also to treat complex polluted environments with multiple heavy metal ions, demonstrating its wide applicability.

[0115] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a zeolite / zero-valent iron-microorganism composite adsorbent for removing organophosphorus flame retardants from water, characterized in that, The preparation method includes the following steps: S21. Add the prescribed amount of bacterial suspension and zeolite / zero-valent iron to a container and mix thoroughly. The bacterial cells in the bacterial suspension are the functional microorganism *Novosphingobium tardaugens*. The mass ratio of the bacterial suspension to the zeolite / zero-valent iron is 2-2.5:1-1.5; the concentration of the bacterial suspension is 100-120 g / L. S22. Seal the container with sealing film, place the container on a shaker, and load the bacterial cells in the bacterial suspension onto zeolite / zero-valent iron to obtain a loaded mixture; S23. Take out the loaded mixture, filter the loaded mixture to obtain solid powder, freeze dry the solid powder and store it at -4 to -3℃ for later use to obtain zeolite / zero-valent iron-microorganism composite adsorbent. The preparation method of the zeolite / zero-valent iron includes the following steps: S1. Mix FeCl3 solution with zeolite, and adjust the pH to 3-4 using alkaline solution to obtain the first mixed solution; S2. Mix the first mixed solution under ultrasonic conditions; S3. Continue stirring with a mechanical stirrer while gradually adding NaBH4 solution dropwise. After the addition is complete, continue stirring to obtain the second mixed solution. S4. The second mixed solution is separated into solid and liquid components to obtain a black solid powder. The black solid powder is then washed and freeze-dried to obtain zeolite / zero-valent iron.

2. The preparation method of the zeolite / zero-valent iron-microorganism composite adsorbent according to claim 1, characterized in that, In step S21, the method for preparing the bacterial suspension includes: Add the bacterial seed culture to sterile nutrient medium, then culture it in a shaker at 25-35°C for 22-24 hours. Remove the culture, centrifuge, collect all the bacterial cells, wash them with sterile water, and then prepare a bacterial suspension with sterile water.

3. The preparation method of the zeolite / zero-valent iron-microorganism composite adsorbent according to claim 1, characterized in that, In step S1, the concentration of the FeCl3 solution is 0.15–0.25 mol / L; The mass ratio of the FeCl3 solution to the zeolite is 3-4:1; The alkaline solution is a NaOH solution with a concentration of 0.5–1.5 mol / L.

4. The preparation method of the zeolite / zero-valent iron-microorganism composite adsorbent according to claim 1, characterized in that, In step S2, the mixing temperature is 25–35°C and the mixing time is 10–20 min.

5. The preparation method of the zeolite / zero-valent iron-microorganism composite adsorbent according to claim 1, characterized in that, In step S3, the concentration of the NaBH4 solution is 0.5–1 mol / L, and the dropping rate is 1–3 mL / s.

6. The preparation method of the zeolite / zero-valent iron-microorganism composite adsorbent according to claim 1, characterized in that, In step S4, the solid-liquid separation step of the second mixed solution includes: letting the solution stand for 4 to 6 minutes, followed by filtration. The washing steps include: first washing the black solid powder with deionized water 2 to 4 times, and then washing the black solid powder with anhydrous ethanol 2 to 4 times.

7. The application of a zeolite / zero-valent iron-microorganism composite adsorbent prepared by the preparation method according to any one of claims 1 to 6, characterized in that, The application of the zeolite / zero-valent iron-microorganism composite adsorbent in the removal of organophosphorus flame retardants from water.

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