Method for treating industrial wastewater through photoelectrocatalysis of TiO2 nanotube array film

Abstract

The invention provides a method for treating industrial wastewater through photoelectrocatalysis of a TiO2 nanotube array film, and belongs to the technical field of industrial wastewater treatment.The method comprises the steps that firstly, the TiO2 nanotube array film is prepared; 2, pretreating the industrial wastewater; 3, taking the TiO2 nanotube array film prepared in the step 1 as a working electrode; 4, introducing oxygen into the photoelectrocatalysis reaction device; and 5, illuminating the photoelectrocatalysis reaction device by using a light source with the wavelength of 300-800nm, and simultaneously applying 1-5V bias voltage between the working electrode and the counter electrode. Through specific anodic oxidation conditions and annealing treatment, the prepared TiO2 nanotube array film has a regular nanotube structure, the specific surface area is increased, more catalytic active sites are provided, meanwhile, the crystallinity of the film is improved, transmission of photon-generated carriers is facilitated, and the recombination rate is reduced.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of industrial wastewater treatment, in particular to a method for photoelectrocatalytic treatment of industrial wastewater by using a TiO2 nanotube array film. BACKGROUND

[0002] Industrial wastewater is complex in composition and contains a large amount of toxic and harmful substances such as heavy metal ions and organic pollutants. If the industrial wastewater is directly discharged without effective treatment, it will cause serious harm to the ecological environment and human health. Traditional industrial wastewater treatment methods such as physical methods, chemical methods and biological methods have the problems of low treatment efficiency, secondary pollution and high treatment cost.

[0003] Photoelectrocatalytic technology as a new type of advanced oxidation technology has attracted widespread attention because it can completely mineralize organic pollutants into carbon dioxide and water under mild conditions and effectively remove heavy metal ions. Among them, TiO2 has become the most commonly used photoelectrocatalytic material due to its good chemical stability, high catalytic activity, low price, non-toxicity and other advantages. However, the commonly used TiO2-based photoelectrocatalytic materials still have the problems of high recombination rate of photo-generated carriers, insufficient response to visible light and limited catalytic active sites in practical application, which leads to the need for further improvement of the treatment efficiency of industrial wastewater.

[0004] Therefore, a method for photoelectrocatalytic treatment of industrial wastewater by using a TiO2 nanotube array film is provided. SUMMARY

[0005] The application provides a method for photoelectrocatalytic treatment of industrial wastewater by using a TiO2 nanotube array film, which optimizes the preparation process of the TiO2 nanotube array film and the photoelectrocatalytic reaction conditions, improves the separation efficiency of photo-generated carriers, enhances the absorption of visible light and increases the catalytic active sites, so as to realize efficient treatment of industrial wastewater and overcome the shortcomings of the prior art.

[0006] The specific technical scheme is as follows:

[0007] A method for photoelectrocatalytic treatment of industrial wastewater by using a TiO2 nanotube array film, comprising the following steps:

[0008] Step 1: Preparation of TiO2 nanotube array film

[0009] Titanium sheet is used as a substrate, and the titanium sheet is ultrasonically cleaned with acetone, ethanol and deionized water for 10-20 minutes, and then dried in a nitrogen atmosphere;

[0010] The titanium sheet after cleaning and drying is placed in an ethylene glycol solution containing 0.5-2% by mass of hydrofluoric acid and 1-5% by mass of glycerol, and an anodic oxidation reaction is carried out at a voltage of 20-60V and a temperature of 20-40℃ for 1-3 hours to prepare a TiO2 nanotube array film;

[0011] The prepared TiO2 nanotube array film is annealed in an air atmosphere at 400-600℃ for 1-2 hours;

[0012] Step two: the industrial wastewater is pretreated, the pH value of the industrial wastewater is adjusted to 3-7, and then the industrial wastewater is placed in a photoelectrocatalytic reaction device;

[0013] Step three: the TiO2 nanotube array film prepared in step one is used as a working electrode, a platinum sheet is used as a counter electrode, and a saturated calomel electrode is used as a reference electrode to form a three-electrode system which is placed in the photoelectrocatalytic reaction device;

[0014] Step four: oxygen is introduced into the photoelectrocatalytic reaction device, and the flow rate of the oxygen is 50-200mL / min;

[0015] Step five: a light source with a wavelength of 300-800nm is used to irradiate the photoelectrocatalytic reaction device, and a bias voltage of 1-5V is applied between the working electrode and the counter electrode to carry out photoelectrocatalytic reaction for 30-120 minutes;

[0016] Step six: during the photoelectrocatalytic reaction, the reaction conditions are adjusted in real time to optimize the photoelectrocatalytic effect according to the following equation:

[0017] The above scheme provides a complete process from the preparation of a TiO2 nanotube array film to the treatment of industrial wastewater. In the film preparation link, specific anodic oxidation conditions (0.5-2% by mass of hydrofluoric acid, 1-5% by mass of glycerol in an ethylene glycol solution, 20-60V voltage, 20-40℃ temperature, and 1-3 hours reaction time) and 400-600℃ air atmosphere annealing treatment can prepare a film with regular nanotube structure and good crystallinity, increase the specific surface area, provide abundant catalytic active sites, and promote the transport of photo-generated carriers; the pretreatment of the industrial wastewater to adjust the pH value to 3-7 creates a suitable environment for subsequent photoelectrocatalytic reaction; the setting of the three-electrode system ensures the normal progress of the photoelectrocatalytic reaction; the introduction of oxygen provides an oxidizing agent, and the specific wavelength of light and the bias voltage excite the photoelectrocatalytic activity of the film, so that the method can efficiently remove pollutants in industrial wastewater.

[0018] In the aforementioned method for photoelectrocatalytic treatment of industrial wastewater using a TiO2 nanotube array thin film, in step 1, the purity of the titanium sheet is not less than 99.5%. By limiting the purity of the titanium sheet to no less than 99.5%, interference with the TiO2 nanotube array thin film preparation process due to excessive impurities in the titanium sheet is avoided, ensuring the stability and consistency of the film preparation, thereby ensuring the film has good photoelectrocatalytic performance and making the subsequent treatment of industrial wastewater more stable and reliable.

[0019] The above-mentioned method for photoelectrocatalytic treatment of industrial wastewater using a TiO2 nanotube array film, wherein, in step 1, 0.1% to 1% by mass of polyethylene glycol is also added to the solution during the anodic oxidation reaction. Adding 0.1% to 1% by mass of polyethylene glycol to the anodic oxidation reaction solution can regulate the growth process of the TiO2 nanotubes, making the prepared nanotubes more uniform in diameter and further optimizing the film structure. A more uniform nanotube structure helps to increase the specific surface area and light absorption performance of the film, enhance the separation and transmission efficiency of photogenerated carriers, and thus improve the overall photoelectrocatalytic activity of the film.

[0020] In the aforementioned method for photoelectrocatalytic treatment of industrial wastewater using a TiO2 nanotube array thin film, in step 2, the pH of the industrial wastewater is adjusted using dilute sulfuric acid or sodium hydroxide solution. By specifying the use of dilute sulfuric acid or sodium hydroxide solution for adjusting the pH of industrial wastewater, these two common and easy-to-control reagents can accurately adjust the pH of the wastewater to an appropriate range of 3-7, providing a stable and suitable acid-base environment for the photoelectrocatalytic reaction, ensuring efficient reaction, and thereby improving the removal of pollutants from industrial wastewater.

[0021] The above-mentioned method for photoelectrocatalytic treatment of industrial wastewater using a TiO2 nanotube array thin film, wherein, in step 5, the light source is a xenon lamp, and a filter is provided between the xenon lamp and the photoelectrocatalytic reaction device to filter out light within the wavelength range of 300-800nm. By selecting a xenon lamp as the light source and providing a filter to filter light within the 300-800nm ​​wavelength range, the xenon lamp has a wide spectral output, which, in combination with the filter, can provide illumination that matches the absorption spectrum of the TiO2 nanotube array thin film, fully stimulating the film's photoelectrocatalytic activity. Illumination of this specific wavelength can effectively promote the generation of photogenerated carriers, improve the efficiency of the photocatalytic reaction, and enhance the ability to degrade pollutants in industrial wastewater.

[0022] The method for photoelectrocatalytic treatment of industrial wastewater by the TiO2 nanotube array film, wherein, in the step five, the reaction solution is stirred every 10-20 minutes during the photoelectrocatalytic reaction, and the stirring speed is 100-300 rpm. The reaction solution is stirred every 10-20 minutes during the photoelectrocatalytic reaction, and the stirring speed is controlled at 100-300 rpm. The stirring can make the reaction solution uniformly mixed, promote the full contact between the reactants and the TiO2 nanotube array film, accelerate the mass transfer process, make the reaction more sufficient, avoid the local reactant concentration being too high or too low, thereby improving the removal efficiency of the pollutants in the industrial wastewater and ensuring the uniformity of the treatment effect.

[0023] The method for photoelectrocatalytic treatment of industrial wastewater by the TiO2 nanotube array film, wherein, the industrial wastewater contains heavy metal ions and organic pollutants, the heavy metal ions include at least one of chromium ions and cadmium ions, and the organic pollutants include at least one of phenol and aniline. By limiting the typical heavy metal ions (chromium ions and cadmium ions) and organic pollutants (phenol and aniline) contained in the industrial wastewater, it is shown that the method is suitable for treating industrial wastewater containing such common pollutants, and embodies the pertinence and practicality of the method, and provides an effective solution for treating common pollution problems in actual industrial production.

[0024] The method for photoelectrocatalytic treatment of industrial wastewater by the TiO2 nanotube array film, wherein, in the step one, the heating rate during the annealing treatment is 5-10℃ / min. By setting the heating rate during the annealing treatment at 5-10℃ / min, a suitable heating rate can make the TiO2 nanotube array film uniformly heated during the annealing process, avoid the generation of thermal stress in the film due to too fast heating, and affect the film structure and performance. A stable heating rate helps to optimize the crystallization process of the film, improve the crystal structure of the film, and thus improve the photoelectrocatalytic performance and stability of the film.

[0025] The method for photoelectrocatalytic treatment of industrial wastewater by the TiO2 nanotube array film, wherein, in the step four, before the oxygen is introduced, the air in the photoelectrocatalytic reaction device is removed, and the pressure in the device is reduced to 0.01-0.05 MPa. Before the oxygen is introduced, the air in the photoelectrocatalytic reaction device is removed, and the pressure in the device is reduced to 0.01-0.05 MPa. The removal of other gas components in the device avoids the interference of the oxygen with other gases on the reaction, avoids the influence of the mixture of oxygen and other gases on the redox environment of the reaction system, ensures that the introduced oxygen can more effectively participate in the photoelectrocatalytic reaction, provides sufficient and pure oxidizing agent for the reaction, and improves the oxidation removal effect of the pollutants in the industrial wastewater.

[0026] The method for photoelectrocatalytic treatment of industrial wastewater by the TiO2 nanotube array film has the following steps: adding the industrial wastewater into a photoelectrocatalytic reactor, adjusting the pH value of the wastewater, and then adding the TiO2 nanotube array film into the photoelectrocatalytic reactor, and then applying a bias voltage and irradiating the TiO2 nanotube array film with a light source with a specific wavelength range, so as to remove heavy metal ions and organic pollutants in the industrial wastewater. After the photoelectrocatalytic reaction, the treated wastewater is filtered, and then ion exchange resin is used to further remove residual heavy metal ions, and then activated carbon adsorption is used to remove residual organic pollutants. After the photoelectrocatalytic reaction, the post-treatment process of filtering, removing residual heavy metal ions by ion exchange resin, and adsorbing residual organic pollutants by activated carbon is used, the filtration can remove the solid impurities generated in the reaction process; the ion exchange resin has selective adsorption effect on the heavy metal ions, and can further reduce the content of the heavy metal ions in the wastewater; the activated carbon has strong adsorption capacity, and can effectively remove the residual organic pollutants. The multi-step post-treatment process cooperates with each other, so that the treated wastewater can reach a higher purification standard, and the deep treatment and standard discharge of the industrial wastewater are realized.

[0027] The method has the following beneficial effects:

[0028] 1. The TiO2 nanotube array film prepared by the specific anodic oxidation conditions and annealing treatment has a regular nanotube structure, the specific surface area is increased, more catalytic active sites are provided, the crystallinity of the film is improved, the transport of photo-generated carriers is facilitated, and the recombination rate is reduced.

[0029] 2. The addition of polyethylene glycol in the anodic oxidation solution can control the growth of the TiO2 nanotube, so that the tube diameter of the nanotube is more uniform, and the performance of the film is further improved.

[0030] 3. The pH value of the industrial wastewater is adjusted for pretreatment, so that the wastewater is in a suitable reaction environment, and the photoelectrocatalytic reaction efficiency is improved; oxygen is introduced to provide sufficient oxidant for the reaction, and the oxidation capacity for organic pollutants is enhanced.

[0031] 4. The specific wavelength range of the light source and the application of the bias voltage can fully stimulate the photoelectrocatalytic activity of the TiO2 nanotube array film, and improve the removal effect of the heavy metal ions and organic pollutants in the industrial wastewater.

[0032] 5. The reaction process is stirred regularly, and then the subsequent filtration, ion exchange resin treatment and activated carbon adsorption further ensure the treatment effect of the industrial wastewater, so that the treated wastewater can reach the discharge standard. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The flow chart of the method for photoelectrocatalytic treatment of industrial wastewater by the TiO2 nanotube array film provided by the embodiment of the present application;

[0034] Figure 2 The technical effect comparison chart of the first embodiment of the present application shows the improvement of the photo-generated carrier separation efficiency, the chromium ion removal rate and the phenol removal rate.

[0035] Figure 3 The technical effect comparison chart of the embodiment 2 of the present application shows three indexes of photocatalytic activity improvement, cadmium ion removal rate and aniline removal rate.

[0036] Figure 4 The technical effect comparison chart of the embodiment 3 of the present application shows three indexes of photocatalytic reaction rate improvement, chromium / cadmium ion removal rate and phenol / aniline removal rate. DETAILED DESCRIPTION

[0037] The technical solutions of the present application will be further illustrated by specific embodiments in combination with the accompanying drawings.

[0038] In the drawings, only for exemplary illustration, the representation is only a schematic diagram, not a physical diagram, and cannot be understood as a limitation of the present patent; in order to better illustrate the embodiments of the present application, some components in the drawings will be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings can be omitted.

[0039] The same or similar reference numerals in the drawings of the embodiments of the present application correspond to the same or similar components; in the description of the present application, it should be understood that if the terms "upper", "lower", "left", "right", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore the terms describing the positional relationship in the drawings are only for exemplary illustration, and cannot be understood as a limitation of the present patent, for those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0040] In the description of the present application, unless otherwise explicitly specified and limited, if the term "connection" and the like appear to indicate the connection relationship between components, the term should be broadly understood, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two components or the interaction relationship between two components. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0041] Reference Figures 1-4 As shown in the drawings, the present application provides the following three embodiments:

[0042] Embodiment 1

[0043] Titanium sheets with a purity of 99.8% were cleaned with acetone, ethanol and deionized water in sequence for 15 minutes, and then dried under a nitrogen atmosphere.

[0044] The cleaned and dried titanium sheets were placed in an ethylene glycol solution containing 1% by mass of hydrofluoric acid, 3% by mass of glycerol and 0.3% by mass of polyethylene glycol, and an anodization reaction was performed at a voltage of 40 V and a temperature of 30°C for 2 hours to prepare a TiO2 nanotube array film.

[0045] The prepared TiO2 nanotube array film was annealed in an air atmosphere at 500°C for 1.5 hours at a heating rate of 8°C / minute.

[0046] An industrial wastewater containing chromium ions and phenol was taken, and the pH value of the industrial wastewater was adjusted to 5 using dilute sulfuric acid, and then the industrial wastewater was placed in a photoelectrocatalytic reaction device.

[0047] The TiO2 nanotube array film prepared in step 3 was used as a working electrode, a platinum sheet was used as a counter electrode, and a saturated calomel electrode was used as a reference electrode to form a three-electrode system, which was placed in a photoelectrocatalytic reaction device.

[0048] The air in the photoelectrocatalytic reaction device was first removed, and the pressure in the device was reduced to 0.03 MPa, and then oxygen was introduced into the photoelectrocatalytic reaction device at a flow rate of 120 mL / min.

[0049] A xenon lamp was used as a light source, and a filter was placed between the xenon lamp and the photoelectrocatalytic reaction device to screen out light with a wavelength range of 300-800 nm for irradiating the photoelectrocatalytic reaction device, and a bias voltage of 3 V was applied between the working electrode and the counter electrode to perform photoelectrocatalytic reaction for 60 minutes. The reaction solution was stirred every 15 minutes during the reaction at a stirring speed of 200 revolutions / minute.

[0050] After the photoelectrocatalytic reaction was completed, the treated wastewater was filtered, and then ion exchange resin was used to further remove residual chromium ions, and activated carbon adsorption was used to remove residual phenol. It was detected that the removal rate of chromium ions reached 98%, and the removal rate of phenol reached 99%.

[0051] The technical effects of this embodiment are as follows:

[0052] 1. Efficient photo-generated carrier separation and transport: The TiO2 nanotube array film prepared by specific anodization conditions has a regular structure, which greatly increases the specific surface area and provides abundant catalytic active sites. Annealing at 500℃ in air for 1.5 hours with a heating rate of 8℃ / min improves the crystallinity of the film, effectively promotes the transport of photo-generated carriers, and reduces the recombination rate. Experimental data show that under the preparation conditions, the separation efficiency of photo-generated carriers is about 30% higher than that of traditional methods, providing sufficient active species for subsequent photoelectrocatalytic reactions.

[0053] 2. Optimized reaction environment and efficient degradation: Adjusting the pH value of industrial wastewater to 5 places the wastewater in a suitable reaction environment, significantly improving the efficiency of photoelectrocatalytic reactions. Passing oxygen at a flow rate of 120 mL / min provides sufficient oxidizing agent for the reaction, enhancing the oxidation capacity of phenol. Under 300-800 nm wavelength light and a 3V bias, the photoelectrocatalytic reaction lasts for 60 minutes, combined with timed stirring, the treatment effect on industrial wastewater containing chromium ions and phenol is remarkable. Experimental tests show that the chromium ion removal rate reaches 98%, and the phenol removal rate reaches 99%, fully demonstrating the high removal efficiency of heavy metal ions and organic pollutants by this method.

[0054] 3. Stable treatment process and good post-treatment effect: First, remove the air in the device to reduce the pressure to 0.03 MPa, reducing the interference of other gases on the reaction. After the photoelectrocatalytic reaction is complete, the post-treatment process of filtration, ion exchange resin to remove residual chromium ions, and activated carbon to adsorb residual phenol further ensures that the treated wastewater meets high standards. Experimental results show that after post-treatment, the residual amounts of chromium ions and phenol in the wastewater are far below the national emission standards, and the treated water quality is stable and reliable.

[0055] Example 2

[0056] Take titanium sheets with a purity of 99.6%, and sequentially clean them with acetone, ethanol, and deionized water for 12 minutes, then dry them under a nitrogen atmosphere.

[0057] Place the cleaned and dried titanium sheets in an ethylene glycol solution containing 0.8% mass fraction of hydrofluoric acid, 2% mass fraction of glycerol, and 0.2% mass fraction of polyethylene glycol, and perform an anodization reaction at a voltage of 35V and a temperature of 28℃ for 2.5 hours to prepare a TiO2 nanotube array film.

[0058] Anneal the prepared TiO2 nanotube array film in an air atmosphere at 450℃ for 1.2 hours with a heating rate of 6℃ / min.

[0059] An industrial wastewater containing cadmium ions and aniline is taken, and the pH value of the industrial wastewater is adjusted to 4 by using a sodium hydroxide solution, and then the industrial wastewater is placed in a photoelectrocatalytic reaction device.

[0060] The TiO2 nanotube array film prepared in step 3 is taken as a working electrode, a platinum sheet is taken as a counter electrode, and a saturated calomel electrode is taken as a reference electrode to form a three-electrode system, which is placed in a photoelectrocatalytic reaction device.

[0061] The air in the photoelectrocatalytic reaction device is first removed, and the pressure in the device is reduced to 0.02 MPa, and then oxygen is introduced into the photoelectrocatalytic reaction device, and the flow rate of the oxygen is 100 mL / min.

[0062] A xenon lamp is used as a light source, and a filter is arranged between the xenon lamp and the photoelectrocatalytic reaction device to screen out light with a wavelength range of 300-800 nm for irradiating the photoelectrocatalytic reaction device, and at the same time, a bias voltage of 2 V is applied between the working electrode and the counter electrode to perform photoelectrocatalytic reaction for 80 minutes, and the reaction solution is stirred every 12 minutes during the reaction process, and the stirring speed is 150 revolutions per minute.

[0063] After the photoelectrocatalytic reaction is completed, the treated wastewater is filtered, and then ion exchange resin is used to further remove residual cadmium ions, and then activated carbon adsorption is used to remove residual aniline. Through detection, the removal rate of cadmium ions reaches 97%, and the removal rate of aniline reaches 98%.

[0064] The technical effects of this embodiment are as follows:

[0065] 1. Precise control of nanotube growth and performance improvement: In an ethylene glycol solution containing 0.8% mass fraction of hydrofluoric acid, 2% mass fraction of glycerol and 0.2% mass fraction of polyethylene glycol, the prepared TiO2 nanotube array film has uniform tube diameter under the conditions of 35V voltage and 28℃ anodic oxidation reaction for 2.5 hours. The film performance is optimized by annealing at 450℃ in air atmosphere at a heating rate of 6℃ / min for 1.2 hours. Experimental data show that the photocatalytic activity of the film in this embodiment is increased by about 25% compared with the film prepared without adding polyethylene glycol, which shows the positive effect of polyethylene glycol on the growth control of nanotubes and the performance improvement of the film.

[0066] 2. Adapted reaction conditions and pollutant removal: The pH value of the industrial wastewater containing cadmium ions and aniline is adjusted to 4 to create favorable conditions for photoelectrocatalytic reaction. 100 mL / min of oxygen is introduced, and the reaction is carried out under specific wavelength illumination and 2V bias voltage for 80 minutes, and the reaction solution is stirred at regular intervals. The experimental results show that the removal rate of cadmium ions reaches 97%, and the removal rate of aniline reaches 98%, which indicates that this method has good removal effect on heavy metal ions and organic pollutants in such industrial wastewater, and verifies the rationality and effectiveness of the reaction condition setting.

[0067] 3. Effective pretreatment and post-treatment synergy: air is extracted to a pressure of 0.02 MPa to reduce interference, and post-treatment uses filtration, ion exchange resin to remove cadmium ions, and activated carbon to adsorb aniline. Experimental data show that after the complete treatment process, the content of cadmium ions and aniline in the wastewater is greatly reduced, meeting the strict discharge requirements, and reflecting the importance of pretreatment and post-treatment synergy in ensuring the quality of wastewater treatment.

[0068] Example 3

[0069] Take titanium sheets with a purity of 99.7%, and sequentially clean them with acetone, ethanol, and deionized water for 18 minutes, then dry them under a nitrogen atmosphere.

[0070] Place the cleaned and dried titanium sheets in an ethylene glycol solution containing 1.2% mass fraction of hydrofluoric acid, 4% mass fraction of glycerol, and 0.5% mass fraction of polyethylene glycol, and perform an anodic oxidation reaction at a voltage of 45V and a temperature of 32℃ for 1.8 hours to prepare a TiO2 nanotube array film.

[0071] Anneal the prepared TiO2 nanotube array film in an air atmosphere at 550℃ for 1.8 hours, with a heating rate of 9℃ / minute.

[0072] Take industrial wastewater containing chromium ions, cadmium ions, phenol, and aniline, adjust the pH of the industrial wastewater to 6 with dilute sulfuric acid, and then place the industrial wastewater in a photoelectrocatalytic reaction device.

[0073] Take the TiO2 nanotube array film prepared in step 3 as the working electrode, platinum as the counter electrode, and a saturated calomel electrode as the reference electrode, and assemble a three-electrode system into the photoelectrocatalytic reaction device.

[0074] First, extract the air in the photoelectrocatalytic reaction device to reduce the pressure in the device to 0.04 MPa, then introduce oxygen into the photoelectrocatalytic reaction device, and the flow rate of oxygen is 150 mL / min.

[0075] Use a xenon lamp as the light source, set a filter between the xenon lamp and the photoelectrocatalytic reaction device to filter out light with a wavelength range of 300-800 nm, and apply a bias voltage of 4V between the working electrode and the counter electrode to perform photoelectrocatalytic reaction for 100 minutes. Stir the reaction solution every 18 minutes during the reaction process at a stirring speed of 250 revolutions per minute.

[0076] After the photoelectrocatalytic reaction, the treated wastewater is filtered, and then ion exchange resin is used to further remove residual chromium ions and cadmium ions, and activated carbon adsorption is used to remove residual phenol and aniline. Test results show that the removal rates of chromium ions and cadmium ions are both above 98%, and the removal rates of phenol and aniline are both above 99%.

[0077] The technical effects of this embodiment are as follows:

[0078] 1. Strengthened thin film preparation and photocatalytic performance: In an ethylene glycol solution containing 1.2% mass fraction of hydrofluoric acid, 4% mass fraction of glycerol, and 0.5% mass fraction of polyethylene glycol, the TiO2 nanotube array thin film is prepared by anodizing for 1.8 hours at a voltage of 45V and a temperature of 32℃, and then annealing at 550℃ in an air atmosphere with a heating rate of 9℃ / min for 1.8 hours. The prepared TiO2 nanotube array thin film has excellent photocatalytic performance. Experimental tests show that the absorption range of the film is widened, and the photocatalytic activity is significantly enhanced. Compared with ordinary TiO2 thin film, the photocatalytic reaction rate is increased by about 40%, which lays a solid foundation for the treatment of complex industrial wastewater.

[0079] 2. Comprehensive wastewater treatment and high removal rate: For complex industrial wastewater containing chromium ions, cadmium ions, phenol and aniline, the pH value is adjusted to 6, 150mL / min oxygen is introduced, and the reaction is carried out under 300-800nm light and 4V bias for 100 minutes with regular stirring. Experimental test results show that the removal rates of chromium ions and cadmium ions are both above 98%, and the removal rates of phenol and aniline are both above 99%, fully demonstrating the excellent ability of this method in treating complex industrial wastewater containing multiple pollutants, and realizing the efficient and simultaneous removal of different types of pollutants.

[0080] 3. Perfect treatment system and discharge standard: Through the complete treatment system of first removing air to 0.04MPa, then carrying out photoelectrocatalytic reaction, and finally filtering, removing multiple heavy metal ions by ion exchange resin, and adsorbing multiple organic pollutants by activated carbon, the experimental results show that the treated wastewater completely meets the national discharge standard, and all pollutant indicators are within the qualified range, which demonstrates the reliability and effectiveness of this treatment method in practical application, and provides a feasible solution for the standard treatment of complex industrial wastewater.

[0081] In the method of photoelectrocatalytic treatment of industrial wastewater by the TiO2 nanotube array thin film, the reaction conditions are optimized in real time during the photoelectrocatalytic reaction process of step five by the following dynamic control equation:

[0082]

[0083] Wherein:

[0084] E opt(t): photoelectrocatalytic efficiency optimization coefficient at t time, used to dynamically adjust light intensity or bias;

[0085] η: quantum efficiency of TiO2 nanotube array film (0.6-0.9, determined by film crystallinity and annealing conditions);

[0086] I0: initial light intensity (W / m 2 );

[0087] α: light absorption coefficient of pollutants (L·mg -1 ·cm -1 ), related to the type of organic matter in wastewater;

[0088] C(t): pollutant concentration at t time (mg / L);

[0089] d: optical path length of the reaction solution (cm);

[0090] k q : oxygen quenching constant (0.01-0.05 L·mg -1 ·s -1 );

[0091] [O2]: dissolved oxygen concentration (mg / L);

[0092] R h : hole transport resistance of nanotube array (Ω·cm 2 ), determined by film preparation parameters.

[0093] Examples:

[0094] 1. Initial parameter setting: according to the type of wastewater (such as containing phenol), set [O2] = 8 mg / L (when the oxygen flow is 150 mL / min);

[0095] 2. Real-time monitoring: detect the pollutant concentration C(t) every 10 minutes, and substitute it into the equation to calculate E opt (t);

[0096] 3. Dynamic adjustment: if E opt (t) decreases by more than 10%, increase the bias by 0.5 V or the light intensity by 20% to compensate for the loss of efficiency.

[0097] Technical effects:

[0098] 1. Adaptive optimization: by dynamically correlating pollutant concentration, dissolved oxygen and film performance, the reaction conditions are adjusted in real time to avoid waste of light energy or insufficient reaction, which can significantly improve the degradation efficiency;

[0099] 2. Energy saving: when the pollutant concentration decreases (C(t) decreases), the light or bias requirement is automatically reduced, which can significantly reduce energy consumption;

[0100] 3. Anti-interference ability: through R h Parameters compensate for performance degradation caused by film aging or contamination, extending the service life of the catalyst.

[0101] Working principle process:

[0102] 1. Parameter input: Initialize film characteristics (η, R h ), wastewater absorption coefficient (α) and oxygen concentration;

[0103] 2. Real-time feedback: Online sensors monitor C(t) and [O2], and input equations to calculate E opt (t);

[0104] 3. Dynamic control:

[0105] If E opt (t) ≥ 0.9, maintain current conditions;

[0106] If 0.7≤E opt (t) < 0.9, increase the stirring speed by 50 rpm;

[0107] If E opt (t)<0.7, trigger light source intensity or bias voltage adjustment;

[0108] 4. Cycle iteration: until the reaction is completed, ensuring that the pollutant removal rate is stable at above 95%.

[0109] This equation takes into account the pollutant absorption characteristics (α·C(t)), oxygen mass transfer (k q [O2]) and film structure parameters (R h ) dynamic coupling, breaking through the limitations of traditional fixed condition response; through R h Quantify the hole transport properties of nanotube arrays, directly correlating the fabrication process (e.g., annealing rate) with actual reaction efficiency;

[0110] The equation can be adjusted by adjusting α and k q Adapt to different wastewaters (e.g. ignore α when containing heavy metals and focus on [O2] regulation).

[0111] Application of Example: In the complex wastewater of Example 3, after applying this equation, the phenol degradation time is shortened to 80 minutes (originally 100 minutes), and the energy consumption is reduced by 18%

[0112] In summary, the method for photoelectrocatalytic treatment of industrial wastewater using a TiO2 nanotube array thin film provided in this embodiment has the following advantages:

[0113] 1. The TiO2 nanotube array film prepared by the specific anodic oxidation condition and annealing treatment has regular nanotube structure, increases specific surface area, provides more catalytic active sites, improves film crystallinity, is beneficial to photo-generated carrier transport and reduces recombination rate.

[0114] 2. Adding polyethylene glycol in the anodic oxidation solution can control TiO2 nanotube growth, makes nanotube diameter more uniform and further improves film performance.

[0115] 3. The industrial wastewater is pretreated by pH value adjustment to make the wastewater in suitable reaction environment and improve photoelectrocatalytic reaction efficiency; oxygen is introduced to provide sufficient oxidant for the reaction and enhance oxidation ability to organic pollutants.

[0116] 4. The specific wavelength range light source and applied bias can fully stimulate photoelectrocatalytic activity of the TiO2 nanotube array film and improve removal effect of heavy metal ions and organic pollutants in industrial wastewater.

[0117] 5. The reaction process is stirred regularly and the subsequent filtration, ion exchange resin treatment and activated carbon adsorption further ensure the treatment effect of the industrial wastewater, so that the treated wastewater can reach discharge standard.

[0118] The above is only the preferred embodiment of the present application, and does not limit the implementation and protection scope of the present application. For those skilled in the art, it should be realized that any equivalent replacement and obvious change made according to the content of the present application should be included in the protection scope of the present application.

Claims

1. A method for photoelectrocatalytic treatment of industrial wastewater using a TiO2 nanotube array thin film, characterized in that: The following steps are involved: Step 1: Preparation of TiO2 nanotube array film A titanium sheet was used as a substrate, and the titanium sheet was ultrasonically cleaned with acetone, ethanol, and deionized water in sequence for 10 to 20 minutes, and then dried under a nitrogen atmosphere; The cleaned and dried titanium sheet is placed in an ethylene glycol solution containing 0.5% to 2% by mass of hydrofluoric acid and 1% to 5% by mass of glycerol, and an anodic oxidation reaction is performed at a voltage of 20 to 60 V and a temperature of 20 to 40° C. for 1 to 3 hours to prepare a TiO2 nanotube array film; The prepared TiO2 nanotube array film is annealed in an air atmosphere at 400-600°C for 1-2 hours; Step 2: Pre-treat the industrial wastewater, adjust the pH value of the industrial wastewater to 3-7, and then place the industrial wastewater in a photoelectrocatalytic reaction device; Step 3: The TiO2 nanotube array film prepared in step 1 is used as a working electrode, a platinum sheet is used as a counter electrode, and a saturated calomel electrode is used as a reference electrode to form a three-electrode system and place it in a photoelectrocatalytic reaction device; Step 4: introducing oxygen into the photoelectrocatalytic reaction device at a flow rate of 50 to 200 mL / min; Step 5: Illuminate the photoelectrocatalytic reaction device with a light source having a wavelength of 300-800 nm, apply a bias voltage of 1-5 V between the working electrode and the counter electrode, and conduct the photoelectrocatalytic reaction for 30-120 minutes.

2. The method for treating industrial wastewater using a TiO2 nanotube array thin film photoelectrocatalytically according to claim 1, characterized in that: In the step 1, the purity of the titanium sheet is not less than 99.5%.

3. The method for treating industrial wastewater using a TiO2 nanotube array thin film photoelectrocatalytically according to claim 1, characterized in that: In the step 1, during the anodic oxidation reaction, 0.1% to 1% by mass of polyethylene glycol is added to the solution.

4. The method for treating industrial wastewater using a TiO2 nanotube array thin film photoelectrocatalytically according to claim 1, characterized in that: In the step 2, dilute sulfuric acid or sodium hydroxide solution is used to adjust the pH value of the industrial wastewater.

5. The method for treating industrial wastewater using a TiO2 nanotube array thin film photoelectrocatalytically according to claim 1, characterized in that: In the step 5, the light source is a xenon lamp, and a filter is provided between the xenon lamp and the photoelectrocatalytic reaction device for filtering out light in the wavelength range of 300-800 nm.

6. The method for photoelectrocatalytic treatment of industrial wastewater using a TiO2 nanotube array thin film according to claim 1, characterized in that: In the step 5, during the photoelectrocatalytic reaction, the reaction solution is stirred every 10 to 20 minutes at a stirring speed of 100 to 300 rpm.

7. The method for treating industrial wastewater using a TiO2 nanotube array thin film photoelectrocatalytically according to claim 1, characterized in that: The industrial wastewater contains heavy metal ions and organic pollutants, the heavy metal ions include at least one of chromium ions and cadmium ions, and the organic pollutants include at least one of phenol and aniline.

8. The method for treating industrial wastewater using a TiO2 nanotube array thin film photoelectrocatalytically according to claim 1, characterized in that: In the step 1, during the annealing process, the heating rate is 5-10° C. / min.

9. The method for treating industrial wastewater using a TiO2 nanotube array thin film photoelectrocatalytically according to claim 1, characterized in that: In the fourth step, before introducing oxygen, the air in the photoelectrocatalytic reaction device is first evacuated to reduce the pressure in the device to 0.01-0.05 MPa.

10. The method for treating industrial wastewater using a TiO2 nanotube array thin film photoelectrocatalytically according to claim 1, characterized in that: After the photoelectrocatalytic reaction is completed, the treated wastewater is filtered, and then ion exchange resin is used to further remove residual heavy metal ions, and then activated carbon adsorption is used to remove residual organic pollutants.

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