Preparation method of a graphene oxide / titanium dioxide composite nanomaterial

Abstract

The present invention discloses a preparation method of a graphene oxide / titanium dioxide composite nanomaterial, which hydrothermally reacts polyaniline with tetrabutyl titanate precursor to obtain anatase phase nano-TiO 2 , and then forms modified TiO 2 nano-particles through ultrasonic chemical reaction with an organic molecular assistant, and then drops them into a graphene oxide dispersion liquid for microwave radiation reaction crosslinking, thereby preparing a composite nanomaterial with uniform particle size, strong stability and high photocatalytic activity. The method of the present invention is simple and easy to operate, low in cost, mild in reaction conditions, green and environmentally friendly, safe and hygienic. The obtained composite nanomaterial has functions such as persistent and efficient antibacterial, ultraviolet protection, and photocatalytic degradation of pollutants, and has broad prospects in the fields of textile and clothing, home textiles, environment, daily chemical industry, biological medicine, etc.

Description

Technical Field

[0001] The present invention relates to a preparation method of a graphene oxide / titanium dioxide composite nanomaterial, belonging to the technical field of preparation of functional nanomaterials. Background Art

[0002] With the continuous development of the textile industry chain in recent years, the demand for fiber raw materials and energy in the textile industry has been increasing. However, some links in the textile industry chain also cause certain harm to the environment. For example, the textile printing and dyeing industry discharges a large amount of dye wastewater, causing serious pollution to water resources and soil systems. How to effectively remove dyes in printing and dyeing wastewater is of great significance for the green and sustainable development of China's printing and dyeing industry.

[0003] Due to the unique physical and chemical properties of semiconductor materials, they are widely used in the fields of optics, energy conversion, photocatalytic degradation of pollutants, etc. Among semiconductor materials, titanium dioxide has been favored by many scientists due to its rich content, safety, non-toxicity, and good biocompatibility. As a photocatalyst, titanium dioxide can achieve efficient degradation of pollutants through photocatalytic oxidation and reduction reactions, and can also store and convert energy, providing new solutions to environmental pollution and energy use problems. However, titanium dioxide has a small particle size, a large specific surface area, and is extremely easy to agglomerate, which will reduce its surface energy. At the same time, titanium dioxide has a relatively wide band gap and can only carry out photocatalytic degradation under ultraviolet light. Moreover, due to the easy recombination of photo-generated electrons and holes, the application scope of this material in the field of photocatalysis is greatly affected.

[0004] As one of the derivatives of graphene, graphene oxide not only has a large specific surface area, good adsorption properties, and good optical properties, but also contains a large number of oxygen-containing functional groups on its surface, which can allow positively charged cations to enter between the negatively charged carbon layers, providing convenient conditions for the binding reaction of polymers and inorganic nanoparticles [Lu Ying, Zhu Zhiqiang, Lai Liming. Application of reduced graphene oxide / titanium dioxide composites in the field of photocatalysis [J]. China Science and Technology Information, 2022(8): 98-99]. Research shows that graphene and its related derivatives are excellent conductors of electricity, which is beneficial to the transfer and transmission of photo-generated carriers, can effectively prevent the recombination of photo-generated carriers, thereby improving the photocatalytic activity. Moreover, due to the excellent adsorption properties of graphene, it can adsorb more polar molecules and promote the photocatalytic reaction. Therefore, reacting and combining with graphene oxide to form a composite nanomaterial is beneficial to improving the photocatalytic activity of titanium dioxide.

[0005] Titanium dioxide belongs to oxide semiconductor with limited electrical conductivity. The electrons generated by photoexcitation are easily captured by holes, resulting in a reduction in the number of active charges that can participate in redox reactions and a decrease in the photocatalytic ability of the material. The lamellar structure of graphene oxide can provide a transfer channel for photoexcited electrons. When titanium dioxide and graphene oxide are tightly combined, the generated photoexcited electrons can be transferred to the surface of titanium dioxide in time, preventing their rapid recombination with holes, thereby improving the photocatalytic activity of titanium dioxide [Zhu Zhiqiang, Lai Liming, Lu Ying, etc. Photocatalytic mechanism and progress of graphene / titanium dioxide-based multi-component composites [J]. China Science and Technology Information, 2022(18): 63-65]. Moreover, the unique small-size effect of graphene oxide provides a large specific surface area and porous structure for titanium dioxide, which not only provides more sites for photocatalytic reactions but also helps to adsorb reactants, making the reactants gather towards the photocatalytic material and promoting the progress of redox reactions.

[0006] At present, many studies have reported the preparation methods and photocatalytic applications of graphene oxide / titanium dioxide composites. Hydrothermal method was used to prepare graphene oxide / titanium dioxide composites [Liu Zihao, Jiang Baojun. Study on the photocatalytic oxidation treatment of traditional Chinese medicine pharmaceutical washing wastewater by graphene oxide / titanium dioxide composite [J]. Liaoning Chemical Industry, 2021, 50(5): 610-613], but the titanium dioxide loaded on the surface of graphene oxide showed agglomeration phenomenon, which affected the photocatalytic activity of the composite. Invention patent CN113599279A discloses a preparation method of graphene oxide / titanium dioxide. This method uses more additives and needs to be calcined in a muffle furnace at high temperature. The steps are complex and the cost is high, so it cannot be applied on a large scale. Invention patent CN111437815A discloses a preparation method of graphene / titanium dioxide composite materials using composite metal doping. The reaction process is cumbersome and time-consuming. Crosslinking agents and chemical additives are used, and sodium borohydride is also needed as a reducing agent, which has certain toxicity to the human body and the environment. Therefore, it is urgent to prepare graphene oxide / titanium dioxide composites with high photocatalytic ability by green synthesis methods.

[0007] In this invention, polyaniline is dissolved in an ethanol aqueous solution, and then mixed with tetrabutyl titanate for hydrothermal synthesis reaction in a reaction kettle to obtain anatase phase nano-titanium dioxide. Then, the nano-titanium dioxide and organic molecular additives such as sodium dodecyl sulfate are subjected to ultrasonic chemical reaction to prepare modified nano-titanium dioxide. Finally, the modified nano-titanium dioxide dispersion is dropped into the graphene oxide ethanol solution for microwave radiation crosslinking reaction to obtain nano-TiO 2A graphene oxide / titanium dioxide composite nanomaterial in which fine particles are evenly distributed and firmly bonded on the graphene oxide sheets. Graphene oxide can reduce the band gap of titanium dioxide and enhance its absorption in the visible light region. In addition, graphene oxide has a high specific surface area and excellent electron transfer mobility, which can provide more active sites, prevent the rapid recombination of electrons and holes in titanium dioxide, and significantly improve the photocatalytic performance. The present invention provides a simple and easy green synthesis method for preparing the graphene oxide / titanium dioxide composite material, and the prepared composite nanomaterial has broad application prospects in the fields of textile and clothing, home textiles, environment, daily chemical industry, biomedicine, etc. Summary of the Invention

[0008] The object of the present invention is to provide a preparation method of a graphene oxide / titanium dioxide composite nanomaterial. By using the π-electron conjugation system and delocalization characteristics of polyaniline, the generation and separation of photoinduced electrons and holes in the modified nano-titanium dioxide can be promoted; due to the high specific surface area and excellent electron transfer mobility of graphene oxide, more reaction sites can be provided for combining nano-TiO 2 and effectively prevent the rapid recombination of TiO 2 electron-hole pairs, reduce the band gap of the composite nanomaterial, enhance the photocatalytic reaction activity, and have broad prospects in the fields of textile and clothing, home textiles, environment, daily chemical industry, biomedicine, etc.

[0009] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0010] A graphene oxide / titanium dioxide composite nanomaterial, characterized in that: the composite nanomaterial is first obtained by hydrothermal reaction of polyaniline and tetrabutyl titanate precursor to obtain anatase-phase nano-TiO 2 , and then ultrasonic action with an organic molecular assistant to form modified TiO 2 nano-particles, and then dropped into the graphene oxide dispersion and prepared by microwave radiation reaction. The mass ratio of the polyaniline to the tetrabutyl titanate precursor is 0.06-0.6:1; the mass ratio of the anatase-phase TiO 2 and the organic molecular assistant is 4-30:1.

[0011] Preferably, the interplanar spacing of graphene oxide is 0.761-0.835 nm, the sheet thickness is 0.647-0.863 nm, the carboxyl content is 4.06-4.37 mmol / g, and the specific surface area is 610-780 m 2 / g, and its structural formula is as follows:

[0012]

[0013] Preferably, the organic molecular adjuvant is selected from sodium dodecyl sulfate, sodium dodecyl sulfonate, sodium dodecyl benzene sulfonate or polyvinylpyrrolidone, and the viscosity-average molecular weight of the polyvinylpyrrolidone is 8,000 to 55,000.

[0014] The preparation method of the above graphene oxide / titanium dioxide composite nanomaterial is carried out according to the following steps:

[0015] (1) Strongly stir and disperse polyaniline in an ethanol solution with a mass concentration of 60%, then dropwise add tetrabutyl titanate through a constant pressure dropping funnel within 6 - 12 min and continue stirring for 25 - 40 min. Transfer the solution to a polytetrafluoroethylene reaction kettle, react at 150 - 180 °C for 3 - 6 h. After cooling to room temperature, alternately freeze-centrifuge with absolute ethanol and deionized water for 3 - 5 times and discard the supernatant, then vacuum dry at 40 - 60 °C to obtain anatase phase nano-TiO 2 ;

[0016] (2) Disperse the anatase phase nano-TiO 2 obtained in step (1) in an absolute ethanol solution to prepare a dispersion with a mass concentration of 5 - 15 g / L, and add 0.1 mol / L hydrochloric acid solution to adjust the pH of the dispersion to 2.2 - 4.0. Then add an organic molecular adjuvant to the solution for ultrasonic chemical reaction for 1 - 3 h, and then through the impact and shear of a microfluidic homogenizer, a uniform and stable modified TiO 2 nano-particle dispersion system;

[0017] (3) Add graphene oxide to an absolute ethanol solution to prepare a dispersion with a mass concentration of 0.2 - 0.8%, ultrasonically oscillate under ultrasonic waves with a power of 150 - 240 W for 15 - 30 min to obtain a uniform graphene oxide ethanol solution, then dropwise add the modified TiO 2 nano-particle dispersion obtained in step (2) within 5 - 10 min, and stir and react under microwave radiation conditions for 2 - 4 h. Then place the reacted solution in a spray dryer for drying treatment for 20 - 40 min to obtain a graphene oxide / titanium dioxide composite nanomaterial powder in which TiO 2 nano-particles are uniformly distributed and firmly bonded on graphene oxide sheets; the mass ratio of the graphene oxide to the modified TiO 2 nano-particles is 3 - 15:1.

[0018] Preferably, in step (1), the temperature of the freeze-centrifugation is -10 - 12 °C, and the rotation speed is 8,000 - 12,000 r / min; the particle size range of the anatase phase nano-TiO 2 microparticles is 25 - 52 nm, and the Zeta potential is 28.65 - 42.03 mV.

[0019] Preferably, the power of the ultrasonic wave in step (2) is 100 - 180 W.

[0020] Preferably, in step (2), the feeding temperature of the microfluidic homogenizer is 40 - 70 °C, the homogenization pressure is 1200 - 2200 Pa, the liquid flow rate is 60 - 150 mL / min, and the power is 1.5 - 3.7 kW.

[0021] Preferably, in step (3), the microwave radiation power is 200 - 560 W, and the microwave radiation temperature is 80 - 100 °C.

[0022] Preferably, in step (3), the inlet air temperature of the spray dryer is 80 - 120 °C, the moisture evaporation rate is 15 - 50 kg / h, the outlet air temperature is 40 - 60 °C, and the power is 36 - 100 kW.

[0023] Compared with the prior art, the preparation principle and beneficial effects of the graphene oxide / titanium dioxide composite nanomaterial in the present invention are as follows:

[0024] 1. The graphene oxide prepared by the improved Hummers method in the present invention has a high carboxyl content, fewer defects, regular structure, small thickness, and large specific surface area, which is beneficial to the reaction and combination of graphene oxide sheets and TiO 2 nanoparticles, so that the nano TiO 2 particles are easily incorporated into the middle of the graphene oxide sheets to form a uniform and stable composite.

[0025] 2. The present invention uses polyaniline (PANI) and tetrabutyl titanate precursor for hydrothermal reaction to prepare anatase nano TiO 2 , and polyaniline is a chemically stable and environmentally friendly polymer compound with special electrical and optical properties. After doping, the conductivity of polyaniline changes between insulator-semiconductor-conductor; in addition, the polyaniline molecule contains a π-bond structure, with a π-electron conjugation system and delocalization characteristics, which can improve the photoinduced charge transfer efficiency at the interface between TiO 2 and polyaniline, that is, PANI / TiO 2 can promote the generation and separation of photoinduced electrons and holes, increase the photocatalytic efficiency, and polyaniline has excellent light absorption properties, which can improve the utilization rate of visible light by titanium dioxide and enhance the photo-responsive activity of the modified TiO 2 .

[0026] 3. The present invention crosslinks nano TiO 2 particles with an organic molecular assistant through ultrasonic chemical reaction to form modified TiO 2Nanoparticles can promote both homogeneous reactions of substances and the dispersion of nanoparticles by utilizing multiple effects of ultrasonic waves such as dispersion, pulverization, and activation in ultrasonic chemical reactions. At the same time, ultrasonic waves generate cavitation effects, leading to the formation, growth, and collapse of cavitation bubbles in the reaction solution. When the cavitation bubbles collapse, extremely high temperatures above 5000K and high pressures greater than 200MPa are generated within an extremely short time and in an extremely small space of the cavitation bubbles, which provides an energy source for ultrasonic chemical synthesis and greatly accelerates the progress of the reaction. Ultrasonic waves play an activating role in the cross-linking reaction between organic molecular additives and nano-TiO 2 By means of the strong impact and cavitation effect of ultrasonic waves, the water molecules adsorbed on the surface of TiO 2 can be dissociated to form hydroxyl groups, increasing the active groups on the surface of TiO 2 particles, promoting the ultrasonic chemical cross-linking between nano-TiO 2 particles and organic molecular additives, thereby forming modified TiO 2 nanoparticles coated with organic molecular additives with uniform size and strong stability.

[0027] 4. The present invention uses a microfluidic homogenizer to process the dispersion of nano-TiO 2 nanoparticles modified with organic molecular additives. The dispersion of modified nano-TiO 2 nanoparticles is pressurized in the high-pressure chamber of the microfluidic homogenizer and extruded through the micropores of the nozzle to form a high-speed jet flowing into the reaction chamber. The jet flows in the reaction chamber with convective shear, forms turbulence and collides with each other. At the same time, due to the sharp increase in pressure, the liquid is converted into gas and cavitation effects occur. Through shear, collision, and cavitation effects, the modified nano-TiO 2 nanoparticles can achieve the effects of particle size reduction and uniform dispersion, promoting the penetration of modified nano-TiO 2 nanoparticles into the middle of the graphene oxide sheets for cross-linking and binding.

[0028] 5. The present invention adds the dispersion of modified nano-TiO 2 nanoparticles dropwise to the graphene oxide solution under microwave irradiation for reaction. Due to the fast heating rate, short reaction time, and good uniformity of microwave irradiation, the modified nano-TiO 2 nanoparticles can fully contact the active sites on the graphene oxide sheets, significantly accelerating the cross-linking reaction between the modified nano-TiO 2 nanoparticles and graphene oxide, effectively avoiding the easy agglomeration and uneven dispersion of nano-TiO 2 caused by long-term treatment, and making the modified nano-TiO 2The nanoparticles are uniformly bound to the surface of graphene oxide sheets, solving the disadvantages of long reaction cycle, low reaction rate, easy aggregation of nanoparticles in the reaction solution, and uneven distribution on the surface of graphene oxide during the traditional water bath heating reaction. At the same time, the pH of the reaction solution is 2.2 - 4.0, which is less than the isoelectric point pH ≥ 4.0 of the TiO 2 colloidal particles, making the TiO 2 nanoparticles positively charged, which can significantly increase the electrostatic attraction and reaction efficiency of the positively charged TiO 2 nanoparticles for the hydrophilic end of the negatively charged organic molecular additive and the carboxyl groups on the edges of graphene oxide sheets, thus greatly improving the stability of the organic molecular additive modified TiO 2 particles, as well as the loading rate and dispersion uniformity in the graphene oxide sheets.

[0029] 6. First, the present invention forms modified nano-TiO 2 by the crosslinking reaction between nano-TiO 2 and the hydrophilic end of the organic molecular additive, and then uses the positively charged nano-TiO 2 to bind to the edges of graphene oxide sheets. At the same time, the hydrophobic end of the organic molecular additive of the modified nano-TiO 2 particles easily enters the hydrophobic middle part of the graphene oxide sheets for crosslinking reaction, enabling the crosslinking of the nano-TiO 2 particles with the hydrophilic end of the organic molecular additive, and binding to the middle part of the graphene oxide sheets through the hydrophobic end of the organic molecular additive to form a composite nanomaterial with uniform distribution, good stability, and high biological activity; introducing an amphiphilic organic molecular additive into the nano-TiO 2 particles improves the distribution uniformity of nano-TiO 2 in the graphene oxide sheets and the structural stability of its composite material; the organic molecular additive can significantly reduce the surface energy of the TiO 2 particles, weaken the interaction between nanoparticles, and the long-chain polymer of the organic molecular additive will be adsorbed on the surface of the nano-TiO 2 particles with high surface energy to form a steric hindrance effect, increasing the distance between nano-TiO 2 particles and inhibiting the aggregation of TiO 2 particles. At the same time, polar groups such as sulfonic acid groups, sulfate groups, and butyrolactam groups of the organic molecular additive in the graphene oxide / titanium dioxide composite nanomaterial can attract the photogenerated holes of nano-TiO 2 , and the carboxyl groups and epoxy groups of graphene oxide can also attract the holes on the surface of nano-TiO 2 , preventing the holes on the TiO 2The rapid recombination of photo-generated electron-hole pairs increases the carrier concentration of the composite nanomaterials, endowing them with higher visible light response activity. This enables the graphene oxide / titanium dioxide composite nanomaterials to achieve functions such as persistent antibacterial, antiviral, ultraviolet protection, and efficient photocatalysis. They are stable in nature, non-toxic, and safe to use.

[0030] 7. The present invention uses a spray dryer to dry the solution after the reaction of modified TiO 2 nanoparticles with graphene oxide. The solution is sprayed into a mist by a high-speed centrifugal atomizer and then contacts with hot air to be dried into a finished product in a very short time. The drying speed is fast. After atomization, the surface area of the solution greatly increases. In the hot air stream, 95-98% of the water can be evaporated instantly, and the drying time only takes a few seconds. The product has good particle size distribution uniformity, fluidity, and solubility, high purity, good quality, and the production process is simplified, the operation control is convenient, and graphene oxide / titanium dioxide composite nanomaterial powder with TiO 2 nanoparticles uniformly distributed and firmly bonded on the graphene oxide sheets can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is the schematic diagram of the preparation principle of the graphene oxide / titanium dioxide composite nanomaterials of the present invention;

[0032] Figure 2 is the transmission electron microscope image of the graphene oxide / titanium dioxide composite nanomaterials of the present invention, where Figure 2 (a)-(f) correspond to the composite nanomaterials obtained by the method of Comparative Example 2, the composite nanomaterials obtained by the method of Comparative Example 3, the composite nanomaterials obtained by the method of Example 1, the composite nanomaterials obtained by the method of Example 2, the composite nanomaterials obtained by the method of Example 3, and the composite nanomaterials obtained by the method of Example 4, respectively. DETAILED DESCRIPTION OF THE INVENTION

[0033] For a better understanding of the technical features, objectives, and beneficial effects of the present invention, the following further illustrates the present invention in conjunction with the accompanying drawings and specific embodiments, but the present invention is not limited to the following embodiments.

[0034] I. Preparation of Graphene Oxide / Titanium Dioxide Composite Nanomaterials

[0035] Example 1

[0036] The graphene oxide / titanium dioxide composite nanomaterials of this example are prepared according to the following steps:

[0037] (1) Strongly stir and disperse polyaniline in an ethanol aqueous solution with a mass concentration of 60%. Then, dropwise add tetrabutyl titanate through a constant-pressure dropping funnel within 6 min and continuously stir for 30 min to make the mass ratio of polyaniline to tetrabutyl titanate 0.08:1. Transfer the solution to a polytetrafluoroethylene reaction kettle and react at 150 °C for 4 h. After cooling to room temperature, alternately freeze-centrifuge (at a temperature of 5 °C and a rotation speed of 10,000 r / min) 3 times with anhydrous ethanol and deionized water and discard the supernatant. Then, vacuum dry at 40 °C to obtain anatase-phase nano-TiO with a particle size of 48 nm and a Zeta potential of 32.73 mV 2 .

[0038] (2) Disperse the anatase-phase nano-TiO obtained in step (1) 2 in an anhydrous ethanol solution to prepare a dispersion with a mass concentration of 12 g / L, and add 0.1 mol / L hydrochloric acid solution to adjust the pH of the dispersion to 2.6. Then, add sodium dodecyl sulfate (the mass ratio of anatase-phase TiO 2 to sodium dodecyl sulfate is 5:1) and carry out ultrasonic (power 120 W) chemical reaction for 2 h. Then, through the impact and shear of a microfluidic homogenizer (feed temperature 45 °C, homogenization pressure 1400 Pa, liquid flow rate 80 mL / min, power 1.8 kW), a uniform and stable modified TiO 2 nano-particle dispersion system is formed.

[0039] (3) Add graphene oxide with an interplanar spacing of 0.815 nm, a sheet thickness of 0.842 nm, a carboxyl content of 4.11 mmol / g, and a specific surface area of 628 m 2 / g to an anhydrous ethanol solution to prepare a dispersion with a mass concentration of 0.4%. Ultrasonically oscillate for 20 min under ultrasonic waves with a power of 180 W to obtain a uniform graphene oxide ethanol solution. Then, dropwise add the modified TiO 2 nano-particle dispersion obtained in step (2) (the mass ratio of graphene oxide to modified TiO 2 nano-particles is 4:1) within 6 min, and stir and react for 2 h under microwave radiation conditions (microwave radiation power 280 W, microwave radiation temperature 85 °C). Then, place the reacted solution in a spray dryer (inlet air temperature 90 °C, water evaporation rate 20 kg / h, outlet air temperature 45 °C, power 56 kW) for drying treatment for 20 min to obtain a graphene oxide / titanium dioxide composite nano-material powder with TiO 2 nano-particles uniformly distributed and firmly bonded on graphene oxide sheets. Through ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS) test and Lambert-Beer's law (Ahv) 2= B(hv - Eg) (where A is the molar absorption coefficient, h is Planck's constant, v is the incident photon frequency, and B is the proportionality constant) to calculate the optical bandgap energy Eg, and the bandgap energy of the composite nanomaterial in this example is 3.13 eV.

[0040] Example 2

[0041] The graphene oxide / titanium dioxide composite nanomaterial of this example was prepared according to the following steps:

[0042] (1) Strongly stir and disperse polyaniline in an ethanol aqueous solution with a mass concentration of 60%. Then, dropwise add tetrabutyl titanate through a constant pressure dropping funnel within 8 min and continue stirring for 35 min, so that the mass ratio of polyaniline to tetrabutyl titanate is 0.16:1. Transfer the solution to a polytetrafluoroethylene reaction kettle and react at 160 °C for 4 h. After cooling to room temperature, alternately freeze - centrifuge (temperature is - 2 °C, rotation speed is 10,000 r / min) 4 times with absolute ethanol and deionized water and discard the supernatant. Then, vacuum - dry at 45 °C to obtain anatase - phase nano - TiO with a particle size of 36 nm and a Zeta potential of 30.03 mV. 2 .

[0043] (2) Disperse the anatase - phase nano - TiO obtained in step (1) 2 in an absolute ethanol solution to prepare a dispersion with a mass concentration of 10 g / L, and add 0.1 mol / L hydrochloric acid solution to adjust the pH of the dispersion to 3.6. Then, add sodium dodecylbenzenesulfonate (the mass ratio of anatase - phase nano - TiO 2 to sodium dodecylbenzenesulfonate is 20:1) and carry out ultrasonic (ultrasonic power is 140 W) chemical reaction for 2 h. Then, through the impact and shear action of a micro - fluidic homogenizer (the feeding temperature of the micro - fluidic homogenizer is 50 °C, the homogenization pressure is 1800 Pa, the liquid flow rate is 95 mL / min, and the power is 2.4 kW), a uniform and stable modified TiO 2 nanoparticle dispersion system is formed.

[0044] (3) Add graphene oxide with an interplanar spacing of 0.793 nm, a sheet thickness of 0.816 nm, a carboxyl content of 4.23 mmol / g, and a specific surface area of 680 m 2 / g to an absolute ethanol solution to prepare a dispersion with a mass concentration of 0.4%. Under ultrasonic oscillation at a power of 200 W for 20 min, a uniform graphene oxide ethanol solution is obtained. Then, dropwise add the modified TiO 2 nanoparticle dispersion in step (2) within 8 min (the mass ratio of graphene oxide to modified TiO 2The mass ratio of the nanoparticles is 10:1), and the mixture is stirred and reacted for 3 h under microwave radiation conditions (microwave radiation power: 360 W, microwave radiation temperature: 90 °C). Then, the reaction solution is placed in a spray dryer (inlet air temperature: 95 °C, moisture evaporation rate: 30 kg / h, outlet air temperature: 45 °C, power: 72 kW) for drying treatment for 30 min to obtain TiO 2 nanoparticles uniformly distributed and firmly bonded on the graphene oxide sheets, i.e., graphene oxide / titanium dioxide composite nanomaterial powder. Through ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS) test and Lambert-Beer's law (Ahv) 2 = B(hv - Eg) (where A is the molar absorption coefficient, h is Planck's constant, v is the incident photon frequency, and B is a proportionality constant), the optical band gap energy Eg is calculated, and the band gap energy of the composite nanomaterial in this example is 3.07 eV.

[0045] Example 3

[0046] The graphene oxide / titanium dioxide composite nanomaterial in this example is prepared according to the following steps:

[0047] (1) Strongly stir and disperse polyaniline in an ethanol aqueous solution with a mass concentration of 60%. Then, dropwise add tetrabutyl titanate through a constant pressure dropping funnel within 10 min and continue stirring for 40 min to make the mass ratio of polyaniline to tetrabutyl titanate 0.25:1. Transfer the solution to a polytetrafluoroethylene reaction kettle and react at 165 °C for 5 h. After cooling to room temperature, alternately freeze and centrifuge (temperature: -5 °C, rotation speed: 11000 r / min) 4 times with anhydrous ethanol and deionized water and discard the supernatant. Then, vacuum dry at 50 °C to obtain anatase phase nano-TiO 2 .

[0048] (2) Disperse the anatase phase nano-TiO 2 obtained in step (1) in an anhydrous ethanol solution to prepare a dispersion with a mass concentration of 6 g / L, and add 0.1 mol / L hydrochloric acid solution to adjust the pH of the dispersion to 3.0. Then, add sodium dodecyl sulfate (the mass ratio of anatase phase TiO 2 to sodium dodecyl sulfate is 10:1) and carry out ultrasonic (ultrasonic power: 168 W) chemical reaction for 2 h. Then, through the impact and shearing action of a microfluidic homogenizer (the feeding temperature of the microfluidic homogenizer is 60 °C, the homogenization pressure is 2000 Pa, the liquid flow rate is 120 mL / min, and the power is 3.2 kW), a uniform and stable modified TiO 2 nanoparticle dispersion system is formed.

[0049] (3) Graphene oxide with an interplanar spacing of 0.768 nm, a sheet thickness of 0.705 nm, a carboxyl content of 4.35 mmol / g, and a specific surface area of 754 m 2 / g was added to an anhydrous ethanol solution to prepare a dispersion with a mass concentration of 0.6%. It was ultrasonically oscillated for 30 min under ultrasonic waves with a power of 220 W to obtain a uniform graphene oxide ethanol solution. Then, the modified TiO 2 nanoparticle dispersion in step (2) was added dropwise within 10 min (the mass ratio of graphene oxide to modified TiO 2 nanoparticles is 8:1), and the mixture was stirred and reacted for 4 h under microwave radiation conditions (microwave radiation power is 420 W, microwave radiation temperature is 100 °C). Then, the reaction solution was placed in a spray dryer (inlet air temperature is 100 °C, water evaporation rate is 40 kg / h, outlet air temperature is 50 °C, power is 86 kW) for drying treatment for 35 min to obtain a graphene oxide / titanium dioxide composite nanomaterial powder with TiO 2 nanoparticles uniformly distributed and firmly bonded on the graphene oxide sheets. Through ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS) test and Lambert-Beer's law (Ahv) 2 = B(hv - Eg) (A is the molar absorption coefficient, h is Planck's constant, v is the incident photon frequency, B is the proportionality constant), the optical band gap energy Eg was calculated, and the band gap energy of the composite nanomaterial in this example was obtained as 2.96 eV.

[0050] Example 4

[0051] The graphene oxide / titanium dioxide composite nanomaterial in this example was prepared according to the following steps:

[0052] (1) Polyaniline was strongly stirred and dispersed in an ethanol aqueous solution with a mass concentration of 60%. Then, tetrabutyl titanate was added dropwise through a constant pressure dropping funnel within 10 min and continuously stirred for 40 min to make the mass ratio of polyaniline to tetrabutyl titanate 0.4:1. The solution was transferred to a polytetrafluoroethylene reaction kettle and reacted at 165 °C for 5 h. After cooling to room temperature, it was alternately frozen and centrifuged with anhydrous ethanol and deionized water (temperature is -5 °C, rotation speed is 11,000 r / min) 5 times, and the supernatant was discarded. After vacuum drying at 50 °C, anatase phase nanometer TiO 2 .

[0053] (2) The anatase phase nanometer TiO 2Dispersed in absolute ethanol solution, a dispersion with a mass concentration of 6 g / L was prepared, and 0.1 mol / L hydrochloric acid solution was added dropwise to adjust the pH of the dispersion to 3.0. Then, polyvinylpyrrolidone with a viscosity-average molecular weight of 25,000 (the mass ratio of anatase TiO 2 to polyvinylpyrrolidone is 10:1) was added to the solution, and an ultrasonic chemical reaction (ultrasonic power: 168 W) was carried out for 2 h. Then, through the impact and shearing of a microfluidic homogenizer (the feeding temperature of the microfluidic homogenizer is 60 °C, the homogenization pressure is 2000 Pa, the liquid flow rate is 120 mL / min, and the power is 3.2 kW), a uniform and stable modified TiO 2 nanoparticle dispersion system was formed.

[0054] (3) Graphene oxide with an interplanar spacing of 0.780 nm, a sheet thickness of 0.683 nm, a carboxyl content of 4.32 mmol / g, and a specific surface area of 721 m 2 / g was added to absolute ethanol solution to prepare a dispersion with a mass concentration of 0.6%. It was ultrasonically oscillated for 30 min under ultrasonic waves with a power of 220 W to obtain a uniform graphene oxide ethanol solution. Then, the modified TiO 2 nanoparticle dispersion in step (2) was added dropwise within 10 min (the mass ratio of graphene oxide to modified TiO 2 nanoparticles is 8:1), and a stirring reaction was carried out for 4 h under microwave radiation conditions (microwave radiation power: 460 W, microwave radiation temperature: 100 °C). Then, the reacted solution was placed in a spray dryer (inlet air temperature: 100 °C, water evaporation rate: 45 kg / h, outlet air temperature: 55 °C, power: 92 kW) for drying treatment for 40 min to obtain a graphene oxide / titanium dioxide composite nanomaterial powder in which TiO 2 nanoparticles are uniformly distributed and firmly bonded on the graphene oxide sheets. Through ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS) testing and the Lambert-Beer law (Ahv) 2 = B(hv - Eg) (A is the molar absorption coefficient, h is Planck's constant, v is the incident photon frequency, and B is the proportionality constant), the optical band gap energy Eg was calculated, and the band gap energy of the composite nanomaterial in this example was obtained as 3.03 eV.

[0055] Comparative Example 1 (without adding polyaniline)

[0056] The graphene oxide / titanium dioxide composite nanomaterial of this example was prepared according to the following steps:

[0057] (1) Tetrabutyl titanate was added dropwise to an aqueous ethanol solution with a mass concentration of 60% within 10 min through a constant-pressure dropping funnel, and then continuously stirred for 40 min. The solution was transferred to a polytetrafluoroethylene reactor and reacted at 165 °C for 5 h. After cooling to room temperature, it was alternately frozen and centrifuged (temperature -5 °C, rotation speed 11000 r / min) 4 times with absolute ethanol and deionized water, and the supernatant was discarded. After vacuum drying at 50 °C, anatase-phase nano-TiO with a particle size of 67 nm and a Zeta potential of 29.36 mV was obtained. 2 .

[0058] (2) The anatase-phase nano-TiO obtained in step (1) 2 was dispersed in an absolute ethanol solution to prepare a dispersion with a mass concentration of 6 g / L, and 0.1 mol / L hydrochloric acid solution was added dropwise to adjust the pH of the dispersion to 3.0. Then, sodium dodecyl sulfate (the mass ratio of anatase-phase TiO 2 to sodium dodecyl sulfate was 10:1) was added to the solution, and a chemical reaction was carried out by ultrasonic wave (ultrasonic power 168 W) for 2 h. Then, through the impact and shearing action of a microfluidic homogenizer (the feed temperature of the microfluidic homogenizer was 60 °C, the homogenization pressure was 2000 Pa, the liquid flow rate was 120 mL / min, and the power was 3.2 kW), a uniformly stable modified TiO 2 nanoparticle dispersion system was formed.

[0059] (3) Graphene oxide with an interplanar spacing of 0.768 nm, a sheet thickness of 0.705 nm, a carboxyl content of 4.35 mmol / g, and a specific surface area of 754 m 2 / g was added to an absolute ethanol solution to prepare a dispersion with a mass concentration of 0.6%. It was ultrasonically oscillated for 30 min under ultrasonic waves with a power of 220 W to obtain a uniform graphene oxide ethanol solution. Then, the modified TiO 2 nanoparticle dispersion obtained in step (2) was added dropwise within 10 min (the mass ratio of graphene oxide to modified TiO 2 nanoparticles was 8:1), and a stirring reaction was carried out under microwave radiation conditions (microwave radiation power 420 W, microwave radiation temperature 100 °C) for 4 h. Then, the reacted solution was placed in a spray dryer (inlet air temperature 100 °C, water evaporation rate 40 kg / h, outlet air temperature 50 °C, power 86 kW) for drying treatment for 35 min to obtain a graphene oxide / titanium dioxide composite nanomaterial powder in which TiO 2 nanoparticles were uniformly distributed and firmly bonded on the graphene oxide sheets. Through ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS) test and Lambert-Beer's law (Ahv) 2= B(hv - Eg) (where A is the molar absorption coefficient, h is Planck's constant, v is the frequency of incident photons, and B is the proportionality constant) to calculate the optical bandgap energy Eg, and the bandgap energy of the composite nanomaterial in this example is 3.16 eV.

[0060] Comparative Example 2 (without adding organic molecular additives)

[0061] The graphene oxide / titanium dioxide composite nanomaterial of this example was prepared according to the following steps:

[0062] (1) Strongly stir and disperse polyaniline in an ethanol aqueous solution with a mass concentration of 60%, then dropwise add tetrabutyl titanate through a constant pressure dropping funnel within 10 min and continue stirring for 40 min to make the mass ratio of polyaniline to tetrabutyl titanate 0.25:1. Transfer the solution to a polytetrafluoroethylene reaction kettle, react at 165 °C for 5 h. After cooling to room temperature, alternately freeze and centrifuge (temperature is -5 °C, rotation speed is 11000 r / min) 4 times with anhydrous ethanol and deionized water and discard the supernatant, then vacuum dry at 50 °C to obtain anatase phase nano-TiO with a particle size of 28 nm and a Zeta potential of 41.29 mV 2 .

[0063] (2) Disperse the anatase phase nano-TiO in step (1) 2 in an anhydrous ethanol solution to prepare a dispersion with a mass concentration of 6 g / L, and add 0.1 mol / L hydrochloric acid solution to adjust the pH of the dispersion to 3.0. Then, through the impact and shear of a microfluidic homogenizer (the feeding temperature of the microfluidic homogenizer is 60 °C, the homogenization pressure is 2000 Pa, the liquid flow rate is 120 mL / min, and the power is 3.2 kW), form a TiO 2 nano-particle dispersion system.

[0064] (3) Add graphene oxide with an interplanar spacing of 0.768 nm, a sheet thickness of 0.705 nm, a carboxyl content of 4.35 mmol / g, and a specific surface area of 754 m 2 / g to an anhydrous ethanol solution to prepare a dispersion with a mass concentration of 0.6%. Ultrasonically oscillate for 30 min under an ultrasonic wave with a power of 220 W to obtain a uniform graphene oxide ethanol solution. Then, dropwise add the TiO dispersion in step (2) within 10 min 2 nano-particles (graphene oxide and TiO 2The mass ratio of the nanoparticles was 8:1), and the mixture was stirred and reacted for 4 h under microwave radiation conditions (microwave radiation power was 420 W, microwave radiation temperature was 100 °C). Then, the reaction solution was placed in a spray dryer (inlet air temperature was 100 °C, water evaporation rate was 40 kg / h, outlet air temperature was 50 °C, power was 86 kW) for drying treatment for 35 min to obtain the graphene oxide / titanium dioxide composite nanomaterial powder. Through ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS) test and Lambert-Beer's law (Ahv) 2 = B(hv - Eg) (where A is the molar absorption coefficient, h is Planck's constant, v is the incident photon frequency, and B is the proportionality constant) to calculate the optical band gap energy Eg, and the band gap energy of the composite nanomaterial in this example was obtained as 3.19 eV.

[0065] Comparative Example 3 (without adding polyaniline and organic molecular additives)

[0066] The graphene oxide / titanium dioxide composite nanomaterial of this example was prepared according to the following steps:

[0067] (1) Tetrabutyl titanate was dropped into an ethanol aqueous solution with a mass concentration of 60% within 10 min through a constant pressure dropping funnel and then continuously stirred for 40 min. The solution was transferred to a polytetrafluoroethylene reaction kettle and reacted at 165 °C for 5 h. After cooling to room temperature, it was alternately frozen and centrifuged (temperature was -5 °C, rotation speed was 11,000 r / min) 4 times with anhydrous ethanol and deionized water, and the supernatant was discarded. Then, it was vacuum dried at 50 °C to obtain anatase phase nano-TiO with a particle size of 67 nm and a Zeta potential of 29.36 mV 2 .

[0068] (2) The anatase phase nano-TiO obtained in step (1) was dispersed in an anhydrous ethanol solution to prepare a dispersion with a mass concentration of 6 g / L, and 0.1 mol / L hydrochloric acid solution was added dropwise to adjust the pH of the dispersion to 3.0. Then, through the impact and shearing action of a microfluidic homogenizer (the inlet temperature of the microfluidic homogenizer was 60 °C, the homogenization pressure was 2000 Pa, the liquid flow rate was 120 mL / min, and the power was 3.2 kW), a TiO 2 nanoparticle dispersion system was formed. 2

[0069] (3) Graphene oxide with an interplanar spacing of 0.768 nm, a sheet thickness of 0.705 nm, a carboxyl content of 4.35 mmol / g, and a specific surface area of 754 m 2 / g was added to an anhydrous ethanol solution to prepare a dispersion with a mass concentration of 0.6%. It was ultrasonically oscillated for 30 min under an ultrasonic wave with a power of 220 W to obtain a uniform graphene oxide ethanol solution. Then, the TiO obtained in step (2) was added dropwise within 10 min​2 A nanoparticle dispersion (graphene oxide and TiO 2 nanoparticles with a mass ratio of 8:1), and under microwave radiation conditions (microwave radiation power of 420 W, microwave radiation temperature of 100 °C), stir and react for 4 h. Then, place the reacted solution in a spray dryer (inlet air temperature of 100 °C, moisture evaporation rate of 40 kg / h, outlet air temperature of 50 °C, power of 86 kW) for drying treatment for 35 min to obtain graphene oxide / titanium dioxide composite nanomaterial powder. Through ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS) testing and Lambert-Beer's law (Ahv) 2 = B(hv - Eg) (where A is the molar absorption coefficient, h is Planck's constant, v is the incident photon frequency, and B is the proportionality constant) to calculate the optical band gap energy Eg, and the band gap energy of the composite nanomaterial in this example is obtained as 3.26 eV.

[0070] II. Detection tests on the samples obtained in the above examples

[0071] Test item 1: Antibacterial activity analysis of graphene oxide / titanium dioxide composite nanomaterials

[0072] The minimum inhibitory concentration (MIC) refers to the lowest concentration at which an antibacterial agent inhibits the growth of microorganisms and is often used as a quantitative detection index for the antibacterial activity of antibacterial agents. The lower the MIC value, the stronger the antibacterial activity of the antibacterial agent. Take the anatase phase nano-TiO with a particle size of 28 nm and a Zeta potential of 41.29 mV in Example 3 2 and the graphene oxide / titanium dioxide composite nanomaterial samples obtained by the methods of Examples 1 - 4 and Comparative Examples 1 - 3. Prepare culture media containing composite nanoparticles with different concentrations by the serial dilution method. After irradiating with a 75 W LED photocatalytic lamp under UVA ultraviolet light for 30 min, then incubate at 37 °C for 24 h and observe whether colonies are formed. The minimum dispersion liquid concentration without bacterial growth is determined as the minimum inhibitory concentration (MIC) of this antibacterial agent. The test results are shown in Table 1.

[0073] Table 1 Minimum inhibitory concentrations of titanium dioxide and composite nanomaterials

[0074]

[0075] As can be seen from Table 1, the minimum inhibitory concentrations of pure anatase phase nano-TiO 2 against Escherichia coli and Staphylococcus aureus are 0.28 mg / mL and 0.56 mg / mL respectively, while the minimum inhibitory concentration of the graphene oxide / titanium dioxide composite nanomaterial is lower than that of pure TiO 2There is a significant reduction. The minimum inhibitory concentrations of the composite nanomaterials in Example 3 against Escherichia coli and Staphylococcus aureus reach 0.0175 mg / mL and 0.035 mg / mL respectively, and the antibacterial activity is 16 times that of the pure nano-TiO 2 sample. It may be that the nano-TiO 2 particles in the composite nanomaterials undergo photocatalytic reactions under ultraviolet light irradiation to generate reactive oxygen species (ROS), mainly including superoxide ion radicals and hydroxyl radicals. These ROS substances can penetrate the bacterial cell wall and cell membrane, enter the bacterial cells, block their respiratory system and electron transport system, and cause cell death. Graphene oxide has a high specific surface area and a unique structure, which can interact with the bacterial surface, damage the bacterial cell wall and cell membrane, thus leading to bacterial death. In addition, graphene oxide can also adsorb bacterial metabolites and enzymes, further preventing the growth and reproduction of bacteria. Polyaniline has a certain conductivity, can form a conductive network, affect the growth and reproduction of bacteria, and polyaniline can also interact with functional groups such as hydroxyl and amino groups on the bacterial surface, damage the bacterial cell membrane and cell wall, thus inhibiting bacterial growth. The graphene oxide / titanium dioxide composite nanomaterials have a better antibacterial effect on Escherichia coli, which is related to the presence of a thick layer of peptidoglycan in the cell wall of Staphylococcus aureus.

[0076] Test item 2: Photodegradation analysis of graphene oxide / titanium dioxide composite nanomaterials on dyes

[0077] Respectively take 0.3 g of anatase-phase nano-TiO 2 with a particle size of 28 nm and a Zeta potential of 41.29 mV in Example 3, and graphene oxide / titanium dioxide composite nanomaterials obtained by the methods of Examples 1-4 and Comparative Examples 1-3, put them into a beaker, add 50 mL of methylene blue solution with a concentration of 10 mg / L, and use an ultrasonic cleaner to uniformly disperse the photocatalyst in the solution. Before ultraviolet light irradiation, place the sample in a dark box and stir it in the dark for 60 min to achieve adsorption-desorption equilibrium; during ultraviolet light irradiation, under the reaction condition of 25 °C, take a certain amount of the solution at intervals of 20 min, centrifuge it, and take the supernatant and place it in a cuvette, with pure water as the blank reference. According to the absorbance of the dye solution measured at different times, calculate the photocatalytic degradation rate of the composite nanomaterials after 2 h. The test results are shown in Table 2.

[0078] Table 2 Photocatalytic degradation rates of titanium dioxide and composite nanomaterials on methylene blue dye

[0079]

[0080] Pure anatase-phase nano-TiO 2 Due to its relatively wide optical band gap, high electron-hole recombination efficiency, and TiO 2The nanoparticles are prone to aggregation, and the photocatalytic degradation rate of methylene blue dye is only 60.24%. In the graphene oxide / titanium dioxide composite nanomaterials of Examples 1 to 4, both polyaniline and graphene oxide can increase the carrier concentration of nano-TiO 2 and improve its absorption of visible light. At the same time, the positively charged amino groups and negatively charged carboxyl groups of polyaniline and graphene oxide can respectively attract the photo-generated electrons and holes of TiO 2 , reduce the recombination rate of the two, and promote the generation of ROS active substances. Under the synergistic effect of the two, the photocatalytic efficiency of the composite nanomaterial is greatly enhanced. The graphene oxide sheets in the composite nanomaterial show a negative potential and a large specific surface area, increasing the adsorption of positively charged methylene blue molecules. The synergistic effect of dye adsorption and ROS photocatalysis accelerates the degradation efficiency of methylene blue dye. In Comparative Example 1, polyaniline is not added, and the synergistic effect of polyaniline and graphene oxide cannot be exerted, resulting in a decrease in catalytic efficiency; in Comparative Example 2, no organic molecular additive is added, and it is difficult for nano-TiO 2 nanoparticles to be evenly dispersed on the surface of graphene oxide sheets and are prone to agglomeration, resulting in a weakening of the photocatalytic effect; while in Comparative Example 3, neither polyaniline nor organic molecular additive is added, and the formed graphene oxide / titanium dioxide composite nanomaterial has poor structural stability, resulting in a further reduction in the photocatalytic degradation efficiency of the dye.

[0081] Test Item 3: Transmission Electron Microscopy Analysis of Graphene Oxide / Titanium Dioxide Composite Nanomaterials

[0082] The distribution of nano-TiO 2 particles in the graphene oxide sheets was observed using a transmission electron microscope (30,000×). Six samples of the graphene oxide / titanium dioxide composite nanomaterial were taken. The first sample was the composite nanomaterial obtained by the method of Comparative Example 2, the second sample was the composite nanomaterial obtained by the method of Comparative Example 3, the third sample was the composite nanomaterial obtained by the method of Example 1, the fourth sample was the composite nanomaterial obtained by the method of Example 2, the fifth sample was the composite nanomaterial obtained by the method of Example 3, and the sixth sample was the composite nanomaterial obtained by the method of Example 4. The test results are shown in Figure 2 (a) to (f) in turn.

[0083] As shown by Figure 2 : In Comparative Example 2, no organic molecular additive is added. Since nano-TiO 2 cannot enter the middle part of the hydrophobic graphene oxide sheets for cross-linking reaction by means of the hydrophobic end of the organic molecular additive, most of the positively charged nano-TiO 2 is combined at the edges and folds of the graphene oxide sheets and it is difficult to penetrate into the middle part of the graphene oxide sheets. Moreover, some TiO 2 nanoparticles form aggregates at the edges of graphene oxide, resulting in an increase in particle size (seeFigure 2 (a)). In Comparative Example 3 without the addition of polyaniline and organic molecular additives, due to the lack of the electrostatic binding effect of the imino group of polyaniline and polar groups such as sulfonic acid group, sulfate group, and butyrolactam group of organic molecular additives, it is also impossible to diffuse and react into the middle of graphene oxide sheets through the hydrophobic end of the amphiphilic organic molecular additive, resulting in the easy agglomeration of nano-TiO 2 particles. The nano-TiO 2 microparticles show obvious accumulation on the surface of graphene oxide, and the particle size becomes significantly larger (see Figure 2 (b)). As polyaniline and organic molecular additives are added in different amounts (as shown in Figure 2 (c) - (f)), through the electrostatic binding of the imino group of polyaniline and polar groups such as sulfonic acid group, sulfate group, and butyrolactam group of organic molecular additives to nano-TiO 2 , the aggregation of nano-TiO 2 particles at the edges and folds of graphene oxide sheets is improved; the hydrophilic end of the organic molecular additive can crosslink with TiO 2 particles to form modified nano-TiO 2 . At the same time, with the help of the hydrophobic end of the organic molecular additive, it is easy to enter the hydrophobic middle of graphene oxide sheets for crosslinking and binding, thereby forming a composite nanomaterial with uniform distribution, good stability, and high biological activity; at the same time, the amphiphilic organic molecular additive can significantly reduce the surface energy of TiO 2 microparticles, weaken the interaction between TiO 2 particles, and the hydrophobic long chain of the organic molecular additive can form a steric hindrance effect, increasing the spacing of TiO 2 nano-particles and preventing the agglomeration of TiO 2 particles. Therefore, the nano-TiO 2 modified by polyaniline and organic molecular additives has a smaller particle size, and most of the modified TiO 2 microparticles are more evenly loaded on the edges and middle parts of graphene oxide sheets, forming a composite nanomaterial with strong stability and high photocatalytic activity.

[0084] In summary, anatase-phase nano-TiO 2 is obtained by the hydrothermal reaction of polyaniline and tetrabutyl titanate precursor, and then modified TiO 2 nano-particles are formed by ultrasonic chemical reaction with organic molecular additives. Then, it is dropped into the graphene oxide dispersion for microwave radiation reaction crosslinking, and further a graphene oxide / titanium dioxide composite nanomaterial with uniform particle size, stable structure, and high photocatalytic activity is obtained. Polyaniline has a high visible light absorption coefficient and conductivity, which can effectively inhibit the rapid recombination of electrons and holes of TiO 2 , and increase TiO 2The visible light utilization rate, and at the same time, graphene oxide has a high specific surface area and excellent electron transfer mobility, which can prevent the recombination of electrons and holes in TiO 2 and reduce its band gap, enhancing the photocatalytic ability. The method of the present invention is simple, easy to implement, low in cost, controllable in reaction conditions, green and environmentally friendly, and the obtained graphene oxide / titanium dioxide composite nanomaterial has great application potential in the fields of textile and clothing, home textiles, environment, daily chemical industry, biomedicine, etc.

[0085] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A graphene oxide / titanium dioxide composite nanomaterial, Characterized in that: The composite nanomaterial is prepared by first subjecting aniline and tetrabutyl titanate precursor to hydrothermal reaction to obtain anatase-phase nano-TiO 2 , then subjecting it to ultrasonic treatment with an organic molecular additive to form modified TiO 2 nano-particles, and then dropping them into a graphene oxide dispersion liquid for microwave radiation reaction; the mass ratio of the aniline to the tetrabutyl titanate precursor is 0.06 to 0.6:1; the mass ratio of the anatase-phase nano-TiO 2 and the organic molecular additive is 4 to 30:1; The preparation method of the graphene oxide / titanium dioxide composite nanomaterial is carried out according to the following steps: (1) Stir and disperse polyaniline in an aqueous solution of ethanol with a mass concentration of 60%. Then, add tetrabutyl titanate dropwise through a constant-pressure dropping funnel within 6 - 12 min and continue stirring for 25 - 40 min. Transfer the solution to a polytetrafluoroethylene reaction kettle and react at 150 - 180 °C for 3 - 6 h. After cooling to room temperature, alternately freeze-centrifuge with absolute ethanol and deionized water for 3 - 5 times, discard the supernatant, and then vacuum dry at 40 - 60 °C to obtain anatase phase nano-TiO 2 ; (2) Disperse the anatase-phase nano-TiO obtained in step (1) 2 in an absolute ethanol solution to prepare a dispersion with a mass concentration of 5 - 15 g / L, and add 0.1 mol / L hydrochloric acid solution to adjust the pH of the dispersion to 2.2 - 4.

0. Then, add an organic molecular assistant to the solution and carry out ultrasonic chemical reaction for 1 - 3 h. After that, through the impact and shearing of a microfluidic homogenizer, a uniformly stable modified TiO 2 nanoparticle dispersion system is formed; the organic molecular assistant is selected from sodium dodecyl sulfate, sodium dodecyl sulfonate, sodium dodecylbenzenesulfonate or polyvinylpyrrolidone, and the viscosity-average molecular weight of the polyvinylpyrrolidone is 8000 - 55000; (3) Add graphene oxide to an absolute ethanol solution to prepare a dispersion with a mass concentration of 0.2 - 0.8%, and ultrasonically oscillate it for 15 - 30 min under ultrasonic waves with a power of 150 - 240 W to obtain a uniform graphene oxide ethanol solution. Then, add the modified TiO 2 nanoparticle dispersion within 5 - 10 min, and stir and react it for 2 - 4 h under microwave radiation conditions. Then, place the reacted solution in a spray dryer for drying treatment for 20 - 40 min to obtain graphene oxide / titanium dioxide composite nanomaterial powder in which TiO 2 nanoparticles are uniformly distributed and firmly bonded on the graphene oxide sheets; the mass ratio of the graphene oxide to the modified TiO 2 nanoparticles is 3 - 15:

1.

2. The graphene oxide / titanium dioxide composite nanomaterial according to claim 1, Characterized in that: The interplanar spacing of the graphene oxide is 0.761 - 0.835 nm, the sheet thickness is 0.647 - 0.863 nm, the carboxyl group content is 4.06 - 4.37 mmol / g, and the specific surface area is 610 - 780 m 2 / g.

3. The graphene oxide / titanium dioxide composite nanomaterial according to claim 1, Characterized in that: The temperature of the refrigerated centrifugation described in step (1) is -10 to 12 °C, and the rotation speed is 8000 to 12000 r / min; the particle size range of the anatase phase nano-TiO 2 is 25 to 52 nm, and the Zeta potential is 28.65 to 42.03 mV.

4. The graphene oxide / titanium dioxide composite nanomaterial according to claim 1, Characterized in that: In step (2), the power of the ultrasonic wave is 100 - 180 W.

5. The graphene oxide / titanium dioxide composite nanomaterial according to claim 1, Characterized in that: In step (2), the feeding temperature of the microfluidic homogenizer is 40 - 70 °C, the homogenization pressure is 1200 - 2200 Pa, the liquid flow rate is 60 - 150 mL / min, and the power is 1.5 - 3.7 kW.

6. The graphene oxide / titanium dioxide composite nanomaterial according to claim 1, Characterized in that: In step (3), the microwave radiation power is 200 - 560 W, and the microwave radiation temperature is 80 - 100 °C.

7. The graphene oxide / titanium dioxide composite nanomaterial according to claim 1, Characterized in that: In step (3), the inlet air temperature of the spray dryer is 80 - 120 °C, the water evaporation rate is 15 - 50 kg / h, the outlet air temperature is 40 - 60 °C, and the power is 36 - 100 kW.

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