Graphene polyurethane biological carrier and preparation method and application thereof

Abstract

This invention belongs to the field of composite material preparation technology, specifically disclosing a graphene polyurethane biocarrier, its preparation method, and its application. The preparation method includes: mixing a graphene aqueous dispersion with a polyethyleneimine solution to obtain a PEI-graphene dispersion; mixing a MoS2 nanosheet aqueous dispersion with a tannic acid solution to obtain a TA-MoS2 dispersion; mixing the two dispersions, adding conductive carbon black and an aqueous polyurethane binder, and reacting to obtain a graphene-molybdenum disulfide composite slurry; mixing with a polyether polyol, deionized water, a foaming catalyst, an organosilicon surfactant, and a silane coupling agent to form a premix; mixing with a polyisocyanate, temperature-controlled curing, and solidification to obtain the graphene polyurethane biocarrier. This graphene polyurethane biocarrier exhibits high strength, large specific surface area, high porosity, biocompatibility, and high mass transfer efficiency, among other excellent properties. When used in water treatment, it can effectively improve the rate of biochemical reactions.

Description

Technical Field

[0001] This invention belongs to the field of composite material preparation technology, specifically relating to a graphene polyurethane biocarrier, its preparation method, and its application. Background Technology

[0002] With the rapid advancement of industrial modernization, wastewater discharged from industries such as coal chemical, printing and dyeing, and pharmaceutical manufacturing contains a large amount of recalcitrant organic pollutants, such as phenols, anilines, and aromatic sulfides. These pollutants are characterized by high toxicity, difficulty in degradation, and long environmental retention time, seriously threatening the ecological environment and human health. Traditional wastewater treatment technologies suffer from drawbacks such as low treatment efficiency, high risk of secondary pollution, high operating costs, and narrow applicability, making it difficult to meet current stringent environmental emission standards.

[0003] Biochemical technologies, due to their advantages of high efficiency, environmental friendliness, and high specificity, have shown significant potential in degrading pollutants in water. A core aspect of this lies in constructing high-performance biological carriers. Traditional biological carrier materials, such as polyethylene, polypropylene, polyurethane foam, or inorganic ceramic particles, primarily promote biofilm formation through physical retention and surface adsorption. However, these conventional materials have several drawbacks: either they have limited specific surface area and high surface chemical inertness, and lack an active promoting effect on microbial adsorption and metabolism (e.g., inorganic ceramic particles, polyethylene, and polypropylene), leading to either difficulty in biofilm formation, low biofilm formation, slow biofilm initiation, and limited biomass; or they have short lifespans, aging into fragments or powder within 1-2 years (e.g., polyurethane foam). Furthermore, these materials have high electrical resistance, hindering improvements in pollutant treatment efficiency. To improve carrier performance, some researchers have attempted to introduce functional nanomaterials. For example, incorporating carbon materials with high specific surface area (such as activated carbon powder and carbon nanotubes) into a polymer matrix can enhance the carrier's adsorption capacity. However, simple blending can easily lead to the aggregation of nanomaterials, which may detach from the matrix during long-term operation, causing performance degradation and secondary pollution. Furthermore, these materials primarily enhance physical adsorption, with little direct stimulation of electron transport processes and metabolic activity in microorganisms. Some researchers have also introduced graphene oxide into polyurethane matrices to improve their hydrophilicity. However, graphene oxide lacks electrical conductivity and does not contribute to improving electron transport efficiency in microorganisms. Summary of the Invention

[0004] This invention aims to provide a graphene polyurethane biocarrier, its preparation method, and its application. The graphene polyurethane biocarrier has high strength, large specific surface area, high porosity, biocompatibility, conductivity, anti-aging properties, and can promote microbial activity, effectively remove pollutants from water, and has a long service life.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A method for preparing a graphene polyurethane biocarrier includes the following steps: S1. Mix the graphene aqueous dispersion with the polyethyleneimine solution, heat and stir to obtain PEI-graphene dispersion; S2. Mix the MoS2 nanosheet aqueous dispersion with an equal volume of tannic acid solution and shake to obtain TA-MoS2 dispersion. S3. Mix the PEI-graphene dispersion obtained in S1 and the TA-MoS2 dispersion obtained in S2, add conductive carbon black and water-based polyurethane binder, adjust the pH to alkaline, heat and stir the reaction under nitrogen atmosphere to obtain graphene-molybdenum disulfide composite slurry. S4. Mix the polyether polyol, the graphene-molybdenum disulfide composite slurry obtained in S3, deionized water, foaming catalyst, organosilicon surfactant and silane coupling agent, and stir to form a premix. S5. The premix obtained in S4 is mixed with polyisocyanate, stirred rapidly, poured into a preheated mold for reaction, aged under controlled temperature, cured, and cooled to room temperature to obtain graphene polyurethane biocarrier.

[0006] Preferably, in S1, the heating and stirring temperature is 40~50℃, and the heating and stirring time is 1.5~2h.

[0007] Preferably, in S2, the oscillation temperature is 25~30℃, and the oscillation time is 2~3h.

[0008] Preferably, in S3, the volume ratio of the PEI-graphene dispersion to the TA-MoS2 dispersion is 2~3:5.

[0009] Preferably, in step S3, the pH is adjusted to 8-8.5, and the reaction is carried out under nitrogen atmosphere at 40-50°C with stirring for 6-8 hours.

[0010] Preferably, in step S4, the stirring temperature is 20~25℃, the stirring speed is 300~800rpm, and the stirring time is 10~20min.

[0011] Preferably, in step S5, the rotation speed of the rapid stirring is 2000~2500 rpm, and the time is 5~10 s.

[0012] Preferably, in step S5, the mixture is poured into a mold preheated to 40-45°C and reacted for 30-60 seconds, then heated to 60-80°C for 60-90 minutes to mature, and finally heated to 100-120°C for 60-120 minutes to solidify.

[0013] The present invention also provides a graphene polyurethane biocarrier prepared by the aforementioned preparation method.

[0014] The present invention also provides the application of the graphene polyurethane biocarrier in water treatment.

[0015] Compared with the prior art, the present invention has the following advantages and technical effects: This invention discloses a graphene polyurethane biocarrier, its preparation method, and its application. Graphene and MoS2 nanosheets are surface functionalized using polyethyleneimine (PEI) and tannic acid (TA), respectively. This not only solves the problem of dispersion stability of nanomaterials in aqueous phase but also endows graphene and MoS2 nanosheets with complementary surface charges and reactive functional groups such as amino and phenolic hydroxyl groups.

[0016] MoS2 forms a heterogeneous layered structure with graphene, effectively inhibiting graphene aggregation and uniformly dispersing within the polyurethane matrix, significantly improving the mechanical strength and structural durability of the carrier. Furthermore, MoS2, together with graphene and conductive carbon black, constructs a continuous conductive network, promoting electron transfer between microorganisms, enhancing microbial electron transfer efficiency, and improving the biodegradation efficiency of pollutants. The layered structure and surface functional groups of MoS2 can effectively adsorb and enrich pollutants, and its inherent catalytic activity assists the degradation process. In addition, MoS2 can also serve as a heterogeneous nucleation site during the foaming process, contributing to the formation of a three-dimensional porous framework with high porosity and uniform pore size distribution, thereby improving mass transfer efficiency.

[0017] Utilizing the chemical and thermal stability of graphene, its two-dimensional sheet structure effectively blocks the penetration of oxygen, moisture, and other corrosive media, delaying the oxidation and hydrolytic aging process of the polyurethane matrix. Simultaneously, graphene's high thermal conductivity helps disperse the heat generated during use, preventing degradation caused by localized overheating. Conductive carbon black not only strengthens the electron transport network as a conductive component, but its high specific surface area and surface activity also adsorb and stabilize polymer segments, reducing chain breakage caused by ultraviolet radiation or chemical erosion, thereby improving the structural integrity and functional durability of the carrier in long-term wastewater environments. The introduction of carbon black can also shield ultraviolet light to a certain extent, reducing the photoaging rate of the material. Therefore, the service life of the graphene polyurethane material of this application is significantly extended.

[0018] Under a weakly alkaline environment and nitrogen protection, two nanomaterials with opposite charges self-assemble through strong electrostatic drive, forming a stable and uniform graphene-MoS2 heterocomposite structure through interactions such as hydrogen bonds and covalent bonds. The addition of conductive carbon black further bridges the structure, constructing a pre-crosslinked three-dimensional conductive network. This step ensures efficient and orderly composite formation of the nanomaterials, avoiding agglomeration caused by simple mixing. The nanomaterials are then in-situ locked within the rapidly growing polymer framework using a polyurethane foaming process. The resulting biocarrier not only possesses extremely high porosity and specific surface area but also exhibits excellent compressive strength. This demonstrates that the composite network, acting as a nano-reinforcement, effectively improves the mechanical stability of the carrier, solving the problems of easy detachment of reinforcing phases and limited mechanical enhancement in traditional nanocomposite materials.

[0019] Furthermore, this biocarrier exhibits excellent biocompatibility and adsorption-enrichment capabilities. TA and PEI molecules immobilized on the carrier surface expose their abundant phenolic hydroxyl and amino groups, along with other highly hydrophilic and reactive functional groups, on the inner surface of the pores. This significantly improves the hydrophilicity and biocompatibility of the biocarrier, not only facilitating aqueous wetting and rapid microbial attachment and providing abundant initial binding sites for biofilm formation, but also offering a more suitable microenvironment for microbial growth and promoting their metabolic activity. Simultaneously, the large specific surface area and functional groups generate strong physical and chemical adsorption of pollutants, enriching the target pollutants around the microorganisms and creating a locally high-concentration reaction environment, thereby enhancing the biochemical reaction rate from a reaction kinetics perspective.

[0020] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0021] Figure 1 The porosity statistics of the graphene polyurethane biocarriers prepared in Example 1 and Comparative Examples 1-3 are shown in the figure. Figure 2 The graph shows the specific surface area of ​​the graphene polyurethane biocarriers prepared in Example 1 and Comparative Examples 1-3. Figure 3 The graph shows the compressive strength statistics of the graphene polyurethane biocarriers prepared in Example 1 and Comparative Examples 1-3. Detailed Implementation

[0022] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0024] Source of experimental materials: In this invention, unless otherwise specified, all other test materials and instruments are conventional test materials in the field and can be purchased through commercial channels.

[0025] Example 1 A method for preparing a graphene polyurethane biocarrier includes the following steps: S1. In a 500mL three-necked flask, add 200mL of graphene aqueous dispersion with a concentration of 1mg / mL. While stirring at 300rpm, slowly add 100mL of polyethyleneimine (PEI) aqueous solution with a mass fraction of 10%. After the addition is complete, heat the system to 45℃ and continue stirring for 1.75h. After the reaction is complete, a uniform and stable PEI-graphene dispersion is obtained and cooled to room temperature for later use. S2. Take 50 mL of 0.5 mg / mL MoS2 nanosheet aqueous dispersion and 50 mL of 2 mg / mL tannic acid (TA) aqueous solution, mix them in equal volumes, place them in a constant temperature shaker, and shake for 2.5 h at 28 °C and 150 rpm. After shaking, TA-MoS2 dispersion is obtained. S3. The PEI-graphene dispersion obtained in S1 and the TA-MoS2 dispersion obtained in S2 are mixed in a 1L reactor (volume ratio 3:5). 5g of conductive carbon black (Super P) and 50g of waterborne polyurethane binder are added to the mixture. The pH of the mixture is adjusted to 8.5. Nitrogen gas is introduced into the reactor to replace the air for 30 minutes, and the nitrogen atmosphere is maintained. The mixture is heated and stirred at 500 rpm at 45℃ for 7 hours. After the reaction is completed, a viscous and uniform black graphene-molybdenum disulfide composite slurry is obtained. S4. Add 1000g of polyether polyol, 200g of graphene-molybdenum disulfide composite slurry prepared in S3, 30g of deionized water, 4g of foaming catalyst (A33, a solution of triethylenediamine and propylene glycol), 6g of organosilicon surfactant (L-580) and 10g of silane coupling agent (KH-550) to a 5L beaker in sequence. Place the beaker in a constant temperature water bath at 25℃ and stir at 500rpm for 15min using a high-speed disperser to form a uniform premix. S5. Quickly add 520g of polyisocyanate (PM-200) to the premix from S4. Immediately stir rapidly at 2200rpm for 8s using a high-speed stirrer. Quickly pour the mixture into a mold (40cm×40cm×40cm) with the inner wall coated with a release agent and preheated to 42°C. React for 45s. Transfer the filled mold to an oven and heat it to 70°C for 75min, then heat it to 110°C for 90min. After curing, turn off the oven and allow it to cool to room temperature. After demolding, the graphene polyurethane biocarrier is obtained.

[0026] Example 2 S1. In a 500mL three-necked flask, add 200mL of graphene aqueous dispersion with a concentration of 1mg / mL. While stirring at 300rpm, slowly add 100mL of polyethyleneimine (PEI) aqueous solution with a mass fraction of 10%. After the addition is complete, heat the system to 50℃ and continue stirring for 2h. After the reaction is complete, a uniform and stable PEI-graphene dispersion is obtained and cooled to room temperature for later use. S2. Take 50 mL of 0.5 mg / mL MoS2 nanosheet aqueous dispersion and 50 mL of 2 mg / mL tannic acid (TA) aqueous solution, mix them in equal volumes, place them in a constant temperature shaker, and shake for 3 h at 30 °C and 150 rpm. After shaking, TA-MoS2 dispersion is obtained. S3. The PEI-graphene dispersion obtained in S1 and the TA-MoS2 dispersion obtained in S2 are mixed in a 1L reactor (volume ratio 2:5). 5g of conductive carbon black (Super P) and 50g of waterborne polyurethane binder are added to the mixture. The pH of the mixture is adjusted to 8.5. Nitrogen gas is introduced into the reactor to replace the air for 30 minutes, and the nitrogen atmosphere is maintained. The mixture is heated and stirred at 500 rpm at 50°C for 8 hours. After the reaction is completed, a viscous and uniform black graphene-molybdenum disulfide composite slurry is obtained. S4. Add 1000g of polyether polyol, 200g of graphene-molybdenum disulfide composite slurry prepared in S3, 30g of deionized water, 4g of foaming catalyst (A33, a solution of triethylenediamine and propylene glycol), 6g of organosilicon surfactant (L-580) and 10g of silane coupling agent (KH-550) to a 5L beaker in sequence. Place the beaker in a constant temperature water bath at 25℃ and stir at 800rpm for 10min using a high-speed disperser to form a uniform premix. S5. Quickly add 520g of polyisocyanate (PM-200) to the premix from S4. Immediately stir rapidly at 2500rpm for 5s using a high-speed stirrer. Quickly pour the mixture into a mold (40cm×40cm×40cm) with the inner wall coated with a release agent and preheated to 45°C. React for 45s. Transfer the filled mold to an oven and first heat it to 80°C for 90min, then heat it to 120°C for 60min. After curing, turn off the oven and allow it to cool to room temperature. After demolding, the graphene polyurethane biocarrier is obtained.

[0027] Example 3 S1. In a 500mL three-necked flask, add 200mL of graphene aqueous dispersion with a concentration of 1mg / mL. While stirring at 300rpm, slowly add 100mL of polyethyleneimine (PEI) aqueous solution with a mass fraction of 10%. After the addition is complete, heat the system to 40℃ and continue stirring for 2h. After the reaction is complete, a uniform and stable PEI-graphene dispersion is obtained and cooled to room temperature for later use. S2. Take 50 mL of 0.5 mg / mL MoS2 nanosheet aqueous dispersion and 50 mL of 2 mg / mL tannic acid (TA) aqueous solution, mix them in equal volumes, place them in a constant temperature shaker, and shake for 3 h at 25℃ and 150 rpm. After shaking, TA-MoS2 dispersion is obtained. S3. The PEI-graphene dispersion obtained in S1 and the TA-MoS2 dispersion obtained in S2 are mixed in a 1L reactor (volume ratio 3:5). 5g of conductive carbon black (Super P) and 50g of waterborne polyurethane binder are added to the mixture. The pH of the mixture is adjusted to 8.5. Nitrogen gas is introduced into the reactor to replace the air for 30 minutes, and the nitrogen atmosphere is maintained. The mixture is heated and stirred at 500 rpm at 50°C for 6 hours. After the reaction is completed, a viscous and uniform black graphene-molybdenum disulfide composite slurry is obtained. S4. Add 800g of polyether polyol, 150g of graphene-molybdenum disulfide composite slurry prepared in S3, 30g of deionized water, 3g of foaming catalyst (A33, a solution of triethylenediamine and propylene glycol), 5g of organosilicon surfactant (L-580) and 8g of silane coupling agent (KH-550) to a 5L beaker in sequence. Place the beaker in a constant temperature water bath at 25℃ and stir at 500rpm for 15min using a high-speed disperser to form a uniform premix. S5. Quickly add 450g of polyisocyanate (PM-200) to the premix from S4. Immediately stir rapidly at 2500rpm for 5s using a high-speed stirrer. Quickly pour the mixture into a mold (40cm×40cm×40cm) with the inner wall coated with a release agent and preheated to 45°C. React for 60s. Transfer the filled mold to an oven and first control the temperature to 60°C for 90min, then control the temperature to 100°C for 120min to cure. After curing, turn off the oven and allow it to cool to room temperature. After demolding, the graphene polyurethane biocarrier is obtained.

[0028] Comparative Example 1 A method for preparing a graphene polyurethane biocarrier includes the following steps: S1. In a 500mL three-necked flask, add 200mL of graphene aqueous dispersion with a concentration of 1mg / mL. While stirring at 300rpm, slowly add 100mL of polyethyleneimine (PEI) aqueous solution with a mass fraction of 10%. After the addition is complete, heat the system to 45℃ and continue stirring for 1.75h. After the reaction is complete, a uniform and stable PEI-graphene dispersion is obtained and cooled to room temperature for later use. S2. Add 5g of conductive carbon black (Super P) and 50g of waterborne polyurethane binder to the PEI-graphene dispersion obtained in S1. Heat and stir at 500rpm at 45℃ for 7h. After the reaction is completed, a viscous and uniform black graphene slurry is obtained. S3. Add 1000g of polyether polyol, 200g of graphene slurry prepared in S2, 30g of deionized water, 4g of foaming catalyst (A33, a solution of triethylenediamine and propylene glycol), 6g of organosilicon surfactant (L-580) and 10g of silane coupling agent (KH-550) to a 5L beaker in sequence. Place the beaker in a 25°C constant temperature water bath and stir at 500rpm for 15min using a high-speed disperser to form a uniform premix. S4. Quickly add 520g of polyisocyanate (PM-200) to the premix from S3. Immediately stir rapidly at 2200rpm for 8s using a high-speed stirrer. Quickly pour the mixture into a mold (40cm×40cm×40cm) with the inner wall coated with a release agent and preheated to 42°C. React for 45s. Transfer the filled mold to an oven and first heat to 70°C for 75min, then heat to 110°C for 90min to cure. After curing, turn off the oven and allow it to cool to room temperature. After demolding, the graphene polyurethane biocarrier is obtained.

[0029] Comparative Example 2 A method for preparing a graphene polyurethane biocarrier includes the following steps: S1. In a 500mL three-necked flask, add 200mL of graphene aqueous dispersion with a concentration of 1mg / mL. While stirring at 300rpm, slowly add 100mL of polyethyleneimine (PEI) aqueous solution with a mass fraction of 10%. After the addition is complete, heat the system to 45℃ and continue stirring for 1.75h. After the reaction is complete, a uniform and stable PEI-graphene dispersion is obtained and cooled to room temperature for later use. S2. Take 50 mL of 0.5 mg / mL MoS2 nanosheet aqueous dispersion and 50 mL of 2 mg / mL tannic acid (TA) aqueous solution, mix them in equal volumes, place them in a constant temperature shaker, and shake for 2.5 h at 28 °C and 150 rpm. After shaking, TA-MoS2 dispersion is obtained. S3. The PEI-graphene dispersion obtained in S1 and the TA-MoS2 dispersion obtained in S2 are mixed in a 1L reactor (volume ratio 3:5). 5g of conductive carbon black (Super P) and 50g of waterborne polyurethane binder are added to the mixture. The mixture is stirred at 500rpm for 7 hours at room temperature. After the reaction is complete, a black graphene-molybdenum disulfide composite slurry is obtained. S4. Add 1000g of polyether polyol, 200g of graphene-molybdenum disulfide composite slurry prepared in S3, 30g of deionized water, 4g of foaming catalyst (A33, a solution of triethylenediamine and propylene glycol), 6g of organosilicon surfactant (L-580) and 10g of silane coupling agent (KH-550) to a 5L beaker in sequence. Place the beaker in a constant temperature water bath at 25℃ and stir at 500rpm for 15min using a high-speed disperser to form a uniform premix. S5. Quickly add 520g of polyisocyanate (PM-200) to the premix from S4. Immediately stir rapidly at 2200rpm for 8s using a high-speed stirrer. Quickly pour the mixture into a mold (40cm×40cm×40cm) with the inner wall coated with a release agent and preheated to 42°C. React for 45s. Transfer the filled mold to an oven and heat it to 70°C for 75min, then heat it to 110°C for 90min. After curing, turn off the oven and allow it to cool to room temperature. After demolding, the graphene polyurethane biocarrier is obtained.

[0030] Comparative Example 3 Commercially available ordinary hydrophilic polyurethane foam carrier.

[0031] The effects of the graphene polyurethane biocarriers provided in Example 1 and Comparative Examples 1-2, and the hydrophilic polyurethane foam carriers provided in Comparative Example 3 were verified. In Example 1 and Comparative Examples 1-3 were set as Group A, Group B, Group C, and Group D, respectively.

[0032] Porosity and specific surface area: Porosity was determined using a mercury porosimeter; specific surface area was determined using the nitrogen adsorption-desorption (BET) method.

[0033] Compressive strength: The stress of a cylindrical sample when compressed to 70% of its original height is determined using a universal testing machine.

[0034] The results are as follows Figures 1-3 .

[0035] Depend on Figure 1As can be seen, the graphene polyurethane biocarrier prepared in Example 1 exhibits the highest porosity, indicating that the preparation method can effectively construct and stably maintain a highly developed porous three-dimensional framework structure. In contrast, the porosity of Comparative Example 1 (Group B) and Comparative Example 2 (Group C) is significantly reduced, indicating that the absence or incompleteness of MoS2 in the composite process will impair the pore structure integrity of the final foam, while Comparative Example 3 (Group D) has the lowest porosity.

[0036] Depend on Figure 2 It can be seen that the specific surface area of ​​Example 1 (Group A) is significantly higher than that of all comparative examples. This is due to the uniformly dispersed nanoscale graphene and molybdenum disulfide composite within it. These materials themselves have high specific surface areas and are integrated and fixed on the pore walls of the polyurethane foam, greatly increasing the effective surface area of ​​the material. Comparative Example 1 (Group B) has a lower specific surface area due to the lack of MoS2. Comparative Example 2 (Group C) has a limited increase in specific surface area due to insufficient composite material aggregation, which prevents the full utilization of its surface area-increasing effect. Comparative Example 3 (Group D) has the lowest specific surface area.

[0037] Depend on Figure 3 It is evident that Example 1 (Group A) exhibits the best compressive strength. This demonstrates that PEI and TA-modified graphene and MoS2 can form a strong interfacial bond with the polyurethane matrix, playing a nano-reinforcing role, thereby significantly improving the structural stability and compressive strength of the carrier.

[0038] To verify the performance of the graphene polyurethane biocarrier prepared in Example 1 in water treatment (especially for the removal of toxic, recalcitrant organic matter and nitrogen), the following comparative application tests were conducted.

[0039] The specific experimental plan is as follows: Example 1 and Comparative Examples 1-3: The biological carriers were set as Group A, Group B, Group C, and Group D, respectively. The filling volume of each group of carriers in the reactor was the same, which was 30% of the effective volume of the reactor.

[0040] Four identical laboratory-scale sequencing batch reactors (SBBRs). Each reactor has an effective volume of 10L and is equipped with a mechanical stirrer, microporous aerator, online dissolved oxygen (DO) and pH monitors, a temperature control system (25±1℃), and an influent / effluent / sludge discharge system.

[0041] The composition of the test influent (simulated wastewater) is shown in Table 1 below.

[0042] Table 1. Components of Simulated Wastewater

[0043] Sludge inoculation: taken from municipal wastewater treatment plant A 2The activated sludge from the secondary sedimentation tank of the / O process was inoculated into four reactors after large particles were removed by a 3mm sieve. The initial mixed liquor suspended solids (MLSS) concentration was controlled at 3000 mg / L.

[0044] Operating mode: The SBR process is adopted, and the operation follows an anaerobic / anoxic / aerobic (A / A / O) sequence to simulate an enhanced biological nitrogen and phosphorus removal and co-metabolism environment for recalcitrant organic matter. The cycle time for each batch is 20 hours.

[0045] Phase allocation and control: Anaerobic stage (4h): Stirring, no aeration; Anoxic phase (4h): Stirring, no aeration; Aerobic phase (10h): Aeration, DO controlled at 1.0-2.0mg / L; Sedimentation and drainage stage (1.5h): allow to settle, drainage ratio 50%; Idle phase (0.5h).

[0046] Operation period: The experiment lasted for 70 days.

[0047] Days 1-15: Film attachment and adaptation period.

[0048] Days 16-60: Gradually increase the 4-CP concentration from 5.0 mg / L to the target value of 15.0 mg / L, and increase the treated water volume from 2 L / batch to 5 L / batch. This allows the microbial community to gradually adapt and avoids sudden increases in the concentration of toxic and harmful substances that could inhibit microbial growth. Add 10% sodium carbonate during the reaction process to maintain the reactor pH at no lower than 6.8.

[0049] Days 61-70: Stable Operation and Data Collection Period. The system is operating stably. Influent and effluent water samples are collected every two days to analyze various indicators.

[0050] Water quality was tested using national standard methods, and the water quality indicators included: COD: Potassium dichromate method.

[0051] NH4 + -N: Nessler's reagent spectrophotometry.

[0052] NO3 - -N: Ion chromatography.

[0053] TN: Alkaline potassium persulfate digestion-ultraviolet spectrophotometry.

[0054] TP: Ammonium molybdate spectrophotometry.

[0055] 4-CP concentration: High performance liquid chromatography (HPLC).

[0056] The average of the three sets of data from the last week is shown in Table 2 (unit: mg / L).

[0057] Table 2 Water quality test results

[0058] As shown in Table 2, the graphene-polyurethane biocarrier (Group A) prepared in Example 1 of this invention exhibits excellent comprehensive removal performance when treating simulated wastewater: COD removal rate reaches 94.2%, ammonia nitrogen removal rate reaches 97.9%, total nitrogen removal rate reaches 93.6%, and the removal rate of the recalcitrant organic compound 4-chlorophenol is as high as 97.6%. All effluent indicators are significantly better than those of the comparative example, indicating that the synergistic effect of this carrier in terms of porous structure, conductive network, and biocompatibility can significantly improve wastewater treatment efficiency, and it is particularly suitable for the efficient removal of recalcitrant organic compounds and nitrogen.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a graphene polyurethane biological carrier, characterized in that, Includes the following steps: S1. Mix the graphene aqueous dispersion with the polyethyleneimine solution, heat and stir to obtain PEI-graphene dispersion; S2. Mix the MoS2 nanosheet aqueous dispersion with an equal volume of tannic acid solution and shake to obtain TA-MoS2 dispersion. S3. Mix the PEI-graphene dispersion obtained in S1 and the TA-MoS2 dispersion obtained in S2, add conductive carbon black and water-based polyurethane binder, adjust the pH to alkaline, heat and stir the reaction under nitrogen atmosphere to obtain graphene-molybdenum disulfide composite slurry. S4. Mix the polyether polyol, the graphene-molybdenum disulfide composite slurry obtained in S3, deionized water, foaming catalyst, organosilicon surfactant and silane coupling agent, and stir to form a premix. S5. The premix obtained in S4 is mixed with polyisocyanate, stirred rapidly, poured into a preheated mold for reaction, aged under controlled temperature, cured, and cooled to room temperature to obtain graphene polyurethane biocarrier.

2. The preparation method according to claim 1, characterized in that, In S1, the heating and stirring temperature is 40~50℃, and the heating and stirring time is 1.5~2h.

3. The preparation method according to claim 1, characterized in that, In S2, the oscillation temperature is 25~30℃, and the oscillation time is 2~3h.

4. The preparation method according to claim 1, characterized in that, In S3, the volume ratio of the PEI-graphene dispersion to the TA-MoS2 dispersion is 2~3:

5.

5. The preparation method according to claim 1, characterized in that, In step S3, the pH is adjusted to 8-8.5, and the reaction is carried out under nitrogen atmosphere at 40-50°C with stirring for 6-8 hours.

6. The preparation method according to claim 1, characterized in that, In S4, the stirring temperature is 20~25℃, the stirring speed is 300~800rpm, and the stirring time is 10~20min.

7. The preparation method according to claim 1, characterized in that, In S5, the speed of rapid stirring is 2000~2500 rpm, and the time is 5~10s.

8. The preparation method according to claim 1, characterized in that, In step S5, the mixture is poured into a mold preheated to 40-45°C and reacted for 30-60 seconds. The temperature is then controlled to rise to 60-80°C for 60-90 minutes, and finally raised to 100-120°C for 60-120 minutes to solidify.

9. The graphene polyurethane biocarrier prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the graphene polyurethane biocarrier as described in claim 9 in water treatment.

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