CN111634982B

CN111634982B - Preparation method of anode material for efficient phenol wastewater degradation

Info

Publication number: CN111634982B
Application number: CN202010593680.8A
Authority: CN
Inventors: 赵玉平
Original assignee: Beijing Zhonghe Tianyou Environmental Technology Co ltd
Current assignee: Beijing Zhonghe Tianyou Environmental Technology Co ltd
Priority date: 2020-06-27
Filing date: 2020-06-27
Publication date: 2023-06-30
Anticipated expiration: 2040-06-27
Also published as: CN111634982A

Abstract

The invention provides a preparation method of an anode material for degrading high-efficiency phenol wastewater, which has the advantages of high binding force between lead oxide and a titanium substrate, long service life, good stability, high electrocatalytic oxidation activity, oxygen evolution potential of an anode of 1.81V, and after the anode is used for degrading the phenol wastewater for 100min, the removal rate of phenol is 84.1, and the removal rate of COD is 66.3%.

Description

Preparation method of anode material for efficient phenol wastewater degradation

Technical Field

The invention relates to a preparation method of a high-efficiency anode material, which is used for removing organic pollutants in water by electrocatalytic oxidation, and belongs to the technical field of treating industrial wastewater by electrocatalytic oxidation.

Technical Field

Phenol is an important basic organic chemical raw material, and with the development of industrial economy, particularly the rapid expansion and growth of varieties and yields of synthetic materials, the worldwide demand for phenol and the development of downstream products are continuously increased, and the phenol is widely applied to various industries such as medicine synthesis, paint, dye, explosive, preservative, coal gasification, oil refining, fiber, machinery, pipe and the like. Because of different industrial doors, product types and process conditions, the composition of the waste water and the concentration of phenol are greatly different, and particularly the waste water for processing phenolic resin contains extremely high concentration of phenol.

The phenol toxicity process is as follows: the oxygen radicals can destroy signal molecules regulating cell growth, proliferation and differentiation, cause DNA damage, induce apoptosis and oncogenic mutation.

After the phenol wastewater is treated by an excellent treatment technology, the harm to the environment can be avoided, and the recycling of phenol can be realized, and the method mainly comprises a physical and chemical method, a biological method and a high-grade oxidation method. At present, in actual treatment, the three are often flexibly combined to realize complementary advantages and synergistic promotion and keep the stable operation of the treatment system, wherein the chemical method mainly comprises Fenton method, wet catalytic oxidation, ultrasonic oxidation, photocatalytic oxidation, ozone oxidation, electrocatalytic oxidation and the like.

Electrocatalytic oxidation (ECO) is the production of OH, O by anodic reaction ₃ And the oxidant can thoroughly decompose the organic matters. The method has the advantages of strong oxidizing capacity, large treatment capacity, high treatment efficiency, wide application range, simple equipment, simple operation, safety and reliability and good application prospect. However, the electrocatalytic oxidation reaction has low current efficiency and short service life of the electrode, so that the popularization and industrialized application of the electrocatalytic oxidation reaction are limited. At present, ECO is still in development research at home and abroad, and the preparation of the electrode with high electrocatalytic activity, good conductivity, long service life, low cost and easy processing is still a common pursuit of the technicians in the field.

Electrocatalytic oxidation reactions are generally considered to include systems in which direct oxidation and indirect catalytic oxidation occur at the anode. In the direct oxidation path, organic pollutants are firstly adsorbed on the surface of an anode, oxidized into fatty aldehyde, alcohol, ketone, acid and the like by electron transfer at the anode, and then mineralized and degraded further, and the final product is CO ₂ And H ₂ O, the anode material sequentially goes through three periods of a metal electrode, a graphite electrode and a metal oxide electrode, which is also a three-major electrode material system in electrochemistry. The metal oxide electrode overcomes the defects of the traditional carbon electrode, platinum electrode, lead alloy electrode and the like, and is a hot spot field focused by current electrochemical researchers. Typically, the transition metal is a major component of an electrode comprising platinum group metal oxides, tin antimony oxides, lead dioxide, manganese dioxide, and the like.

Insoluble anodes used in the electrolysis industry should have at least three conditions: high conductivity, better electrocatalytic activity and good corrosion resistance. The titanium-based lead dioxide anode is a novel insoluble metal oxide anode material, and has the characteristics of high oxygen evolution potential, strong oxidizing capacity, good corrosion resistance, good conductivity, capability of passing large current and the like, so that the titanium-based lead dioxide anode is widely applied to metallurgy, environmental protection and electrolytic preparation of various organic matters and inorganic matters. Although PbO ₂ Titanium electrodes have numerous advantages, but due to beta-PbO ₂ Has larger internal stress, causes the plating layer to crack,formation of TiO on a substrate ₂ Resulting in beta-PbO ₂ The plating layer is easy to fall off due to the reduced binding force with the matrix, so that the service life of the electrode is greatly shortened, and the engineering reliability and economic benefit are seriously affected. To solve the above problems, modification of the electrode is currently mainly focused on two aspects: (1) The service life of the electrode is improved by adding an intermediate layer to increase the combination properties of the surface active layer and the matrix; (2) The stability of the electrode is improved by modifying the surface active layer by doping or the like. Among these, in terms of the preparation of the intermediate layer, alternative methods are brush pyrolysis, electrodeposition, and the like. The brush coating thermal decomposition has the volatilization of organic gas, which can harm the health of operators and the environment, and the too low pyrolysis temperature causes insufficient crystallization of metal oxide to affect the catalytic activity of electrodes, and the too high temperature causes peroxidation of titanium base materials and even thermal damage of intermediate layers to cause poor conduction. The electrodeposition method has strong controllability, but can deposit metal layers or alpha-PbO ₂ The effect is not obvious. The titanium wire is oxidized/nitrided in situ, the preparation process is complex, and the defects of limited performance regulation and control and difficult control exist. The use of a noble metal conductive interlayer increases corrosion resistance and conductivity, which contributes to the improvement of electrode stability, but its high cost is not necessarily an engineering application. While pyrolyzing and electrodepositing alpha-PbO ₂ The multiple transition layers can also play a role in increasing the service life.

In the prior art, the Huainan society of teachers (CN 108793339A) discloses a novel method for preparing a high catalytic activity electrode and for electrocatalytically degrading o-chlorophenol, wherein an anodic oxidation method is adopted to prepare a Ti/TiO2NT electrode, and Ti is subjected to electroreduction ⁴⁺ Reduction to Ti ³⁺ Reducing the Ti/TiO ₂ The NT electrode is taken as an anode, the Pt sheet is taken as a cathode, the saturated KCl electrode is taken as a reference electrode, the reduced Ti/TiO2NT electrode is taken as the anode, the stainless steel sheet is taken as the cathode, the saturated KCl electrode is taken as the reference electrode, and the anode is put into 2.0g/L electroplating solution containing Graphene Nano Sheets (GNS); coating a graphene nanosheet interlayer on the prepared titanium dioxide nanotube by adopting an electrodeposition method, and doping rare earth Sm with PbO ₂ The preparation of the surface active layer adopts a direct current deposition method, and the components of the deposition solution are 0.1 to 0.5M Pb(NO ₃ ) ₂ ，0.01～0.02M Sm(NO ₃ ) ₃ ·6H ₂ O and 0.01M NaF, adjusting the pH=2 of the solution, and setting the current density to 50-70 mA/cm ² Electrodepositing at 65 deg.c for 60-100 min. However, the prior art faces several technical problems: (1) The conductivity of the titanium oxide subjected to anodic oxidation treatment is not high, so that graphene is added for improvement to improve the conductivity of the anode, but the anodic titanium oxide is of a porous structure, and the graphene flakes are used for improving the conductivity and blocking pore channels; (2) Although an electrodeposition method is used between graphene and titanium oxide, the binding force is derived from adsorption, no chemical bonding exists, the subsequent electrodeposition of lead oxide tends to cause the reduction of the binding force between the lead oxide and the titanium oxide, and obviously, the prior art has improved activity, but the service life of the graphene and the titanium oxide completely cannot meet the actual production requirement; (3) The lead oxide is beta crystal form, has larger stress and is easy to peel off from the surface of the heavy base material.

In addition, a carbon nanotube doped titanium dioxide nanotube photocatalytic material and a preparation method thereof in the university of inner Mongolia industry CN 109382083A in the prior art. The preparation process comprises the following steps: taking a substrate or a pure titanium sheet with a titanium film plated on the surface as an anode, and generating a titanium dioxide nanotube array on the surface of the anode in situ by utilizing an anodic oxidation method; wherein the electrolyte mainly comprises a fluoride ion-containing compound, carbon nanotubes, an organic solvent and water, and the concentration of the carbon nanotubes in the electrolyte is 0.01-0.1 wt%, preferably 0.05-0.1 wt%; and then taking out the anode, and carrying out annealing treatment under inert atmosphere to obtain the carbon nanotube doped titanium dioxide nanotube photocatalytic material. According to the invention, the doping of the carbon nanotubes and the preparation of the titanium dioxide nanotubes are synchronously carried out, so that the preparation process is simplified, and the obtained photocatalytic material has the advantages of wider absorption wavelength range, higher photocatalytic efficiency, longer cycle service life and the like compared with a pure titanium dioxide nanotube array. The prior art provides a means of compounding carbon nanotubes with oxide films, but faces the following technical problems: (1) The carbon nanotubes are not subjected to any pretreatment, so that the binding force of the rest of titanium oxide is to be considered; (2) The base material can be used as a photocatalytic material and can be widely applied to various fields such as photocatalysis, dye sensitized batteries, gas sensors and the like, and the base material can be used for preparing electrodes without any suggestion.

In addition, the prior art prepares Ti/alpha-PbO ₂ /β-PbO ₂ The lead dioxide electrode with long service life and high catalytic activity is prepared by taking SnO2-Sb2O3 as a bottom layer, taking alpha-PbO 2 as an intermediate layer and taking beta-PbO 2 as a surface active layer, which is disclosed in CN 108217852A Chongqing university, for example. The lead dioxide obtained by the invention is compact and uniform, has smaller particles and larger specific surface area. Meanwhile, the surface active layer has strong adhesive force and is not easy to fall off; the surface is smooth and firm, can resist acid and alkali corrosion, and has good catalytic activity and service life. The preparation method of the titanium-based lead dioxide anode is disclosed by CN 108914122A Shandong Antai environmental protection technology Co., ltd, wherein an electrode with a tin-antimony oxide bottom layer is used as an anode, a titanium plate is used as a cathode, and an alpha-PbO 2 intermediate layer is electrodeposited in sodium hydroxide plating solution in which PbO is dissolved; the modified beta-PbO 2 active layer containing cerium dioxide, bait and fluorine is prepared by electro-deposition by taking a titanium plate as an anode and taking the titanium plate as a cathode, and the titanium-based lead dioxide anode is obtained, for example, a method for preparing a fluorine-containing lead dioxide electrode on a titanium substrate is disclosed in CN 101054684A Zhejiang industrial university. The coating structure of the fluorine-containing lead dioxide electrode is as follows: the surface of the titanium matrix is plated with a tin-antimony oxide bottom layer and alpha-PbO from inside to outside ₂ Layer, fluorine-containing beta-PbO ₂ A layer. The method comprises the steps of carrying out surface roughening treatment on a titanium substrate, plating a tin-antimony oxide bottom layer by a thermal decomposition method, and then carrying out alkaline electroplating on alpha-PbO ₂ And acid composite electroplated fluorine-containing beta-PbO ₂ Obtaining the fluorine-containing beta-PbO of the titanium matrix ₂ The life of the electrode, however, is to be improved due to the weak binding force of the anode prepared by the method.

Based on the above, as Ti/PbO ₂ Improvements in the performance and method of use of electrodes, a number of patents have been issued abroad concerning pretreatment of Ti substrates, anodic oxidation to obtain alpha or beta PbO ₂ As well as coarsening improvements using doping elements, have tended to mature, but there is still a need for improvements in the modification of the lifetime of the anode, and severeLimiting industrial applications.

Disclosure of Invention

Based on the problems in the prior art, the preparation method of the anode material for degrading the high-efficiency phenol wastewater is characterized by comprising the following steps:

(1) Providing a titanium or titanium alloy metal substrate and pre-treating the metal substrate;

(2) Preparing an anodic oxidation solution containing carbon nano tubes;

(3) Taking the metal substrate pretreated in the step (1) as an anode, taking the anode oxidizing solution configured in the step (2) as an electrolyte, performing anodic oxidation treatment on the substrate, forming an anodic oxide film on the surface of the metal substrate, and coating carbon nano tubes inside the anodic oxide film;

(4) Removing part of the anodic oxide film by chemical corrosion to expose the carbon nano tube;

(5) Washing with deionized water to obtain Ti/TiO ₂ -CNT material;

(6) Preparing alkaline lead electrodeposition liquid;

(7) Ti/TiO as obtained in step (5) ₂ The CNT material is used as anode, the platinum sheet is used as cathode, and Ti/TiO is obtained by electrolysis ₂ -CNT/α -lead oxide material, deionized and washed a plurality of times;

(8) Preparing an acidic lead electrodeposition liquid;

(9) Ti/TiO as obtained in step (7) ₂ The CNT/alpha-lead oxide material is used as an anode, a platinum sheet is used as a cathode, and Ti/TiO is obtained by electrolysis ₂ -CNT/α -lead oxide/β -lead oxide material.

Further, the pretreatment in the step (1) comprises mechanical polishing, alkali washing and acid washing, wherein the polishing is sequentially performed by using 300-mesh sand paper and 800-mesh sand paper, and then deionized water washing is performed, the alkali washing is a mixed aqueous solution of 10-20g/L sodium carbonate, 10-20g/L trisodium phosphate, 10-20g/L sodium silicate and 1-2g/L octyl phenol polyoxyethylene ether, and the temperature is 40-50 ^o C, pickling for 10-15min, wherein the pickling is a composite pickling solution of 2-3wt.% of oxalic acid and 1-1.5wt.% of hydrochloric acid, and the pickling temperature is 50-60 ^o C, the time is 30-40min, and the pickling is carried out for removingThe ions were washed multiple times.

Further, the carbon nanotubes in the step (2) are subjected to an acidification treatment, and the acidification process is as follows: placing carbon nano tube in three-mouth flask, passing through 100 ^o C, acidifying mixed acid, and carrying out reflux treatment on cooling water for 5H, wherein the mixed acid is 98wt.% H with the volume ratio of 2.5:1 ₂ SO ₄ And 65% -67wt.% HNO ₃ And (5) mixing acid.

Further, in the step (3), the anodic oxidation solution is 4-5g/L ammonium fluoride, 300-500ml ethylene glycol, 0.15-2 wt.% of aqueous solution of acidized carbon nano tubes, 50-60ml of aqueous solution is used, the voltage is 15-20V, the reaction time is 60-120 min, and the pipe diameters of the carbon nano tubes are 50-70nm, and the lengths of the carbon nano tubes are 5-8 mu m.

Further, the solution of chemical etching in the step (4) is 5-15wt.% tartaric acid, the etching time is 10-15min, and the temperature is 40-50 ^o C。

Further, to enhance Ti/TiO ₂ Conductivity of CNT after step (4) and before step (5), for Ti/TiO ₂ -the CNT material is subjected to a cathodic electrochemical reduction treatment.

Further, the alkaline lead electrodeposition liquid in the step (6) comprises 15-20g/L of lead oxide and 100-120g/L of sodium hydroxide.

Further, the electrolysis parameters of step (7) are as follows: the current density is 30-50mA/cm ² At a temperature of 30-35 DEG C ^o C, the time is 40-50min, and the distance between the polar plates is 1.5-2cm.

Further, the acid lead electrodeposition liquid in the step (8): pb (NO) 0.45mol/L ₃ ) ₂ NaF of 0.01mol/L and proper HNO ₃ And adjusting the pH of the electrolyte to 1-2 by using tartaric acid.

Further, the electrolysis parameters in step (9) are as follows: the electrodeposition time is 1.0-1.5h, the deposition temperature is 40-50 ℃, and the electrodeposition current density is 10-15mA/cm ² The distance between the polar plates is 3-4cm.

Further, the anode has an oxygen evolution potential of 1.81V at 40 ^o C，30mA/cm ² And (3) after the anode is used for simulating phenol wastewater degradation for 100min, the phenol removal rate is 84.1, and the COD removal rate is 66.3%.

(a) Regarding the pretreatment: the pretreatment mainly aims to remove oil stains and other oxides attached to the surface of a titanium plate, and simultaneously etch the titanium-based surface into a fresh uneven rough surface so as to increase the real surface area of a titanium matrix, so that the binding force between an active coating and the matrix is enhanced, the mechanical bonding degree of the active coating is improved, the service life of the coating is prolonged, and the polishing aim is to enable the rough surface of metal to be flat and smooth.

Alkali washing: the titanium substrate is stained with greasy dirt in the course of working, adhere to rust-proof oil, cutting oil, etc. therefore must remove greasy dirt before the pickling process, use sodium carbonate to replace sodium hydroxide, sodium carbonate is weaker than sodium hydroxide in alkalinity, have certain saponification ability, have buffer action to pH value of solution, but its washing performance is poor, therefore add trisodium phosphate, have deoiling and buffering effects by oneself, and the washing performance is good, in addition add sodium silicate, sodium silicate can increase corrosion inhibition performance in the alkaline washing liquid, and use with subsequent octyl phenol polyoxyethylene ether complex, can have certain saponification ability, and as wetting agent, lubricant. The degreasing solution should be heated to enhance saponification and emulsification, and to increase soap solubility, but not so high as to be controlled at 40-50 ^o C

(b) Acid washing: the purpose of the acid treatment is to enhance the binding force between the substrate and the anodic oxide, thereby improving the conductivity and prolonging the service life of the electrode. The surface of the substrate subjected to acid etching can form uneven pitted surface, so that the substrate has larger surface area, the current density is reduced, and the electrochemical performance of the electrode is improved. At the same time, the oxide film on the surface of the titanium substrate can be removed. In general, the surface of a titanium substrate is easily passivated by acid etching with strong oxidizing acid, and weak acid often causes poor mechanical bonding force on the surface of an electrode due to insufficient corrosiveness, and the invention adopts a compound washing solution of 2-3wt. oxalic acid and 1-1.5wt.% hydrochloric acid for acid washing, so that the treated titanium substrate is gray uniform pitting surface and loses metallic luster, and a rough and uneven surface is obtained after acid etching, which is beneficial to subsequent anodic oxidation treatment.

(c) Anodizing: the anodic oxidation liquid ammonium fluoride, ethylene glycol and the acidized carbon nano tube aqueous solution are common anodic oxidation liquid components, wherein the carbon nano tube is mainly added, and the surface of the carbon nano tube is known to have no obvious group, so that the water solubility is extremely poor, and the organic solution is directly put into the electrolyte, so that obvious solid-liquid separation can be invented, and therefore, the carbon nano tube needs to be acidized, and the acidized carbon nano tube has the following processes: placing carbon nano tube in three-mouth flask, passing through 100 ^o C, acidifying mixed acid, and carrying out reflux treatment on cooling water for 5H, wherein the mixed acid is 98wt.% H with the volume ratio of 2.5:1 ₂ SO ₄ And 65% -67wt.% HNO ₃ The mixed acid is grafted on the surface of the mixed acid, the water solubility of the carbon nano tube is obviously improved, and the mixed acid can be perfectly compounded on the surface of the anodic titanium oxide or coated in the anodic oxide film, and the pipe diameter of the carbon nano tube is preferably 50-70nm, the length is 5-8 mu m and the concentration is 0.15-2 wt.% for facilitating the subsequent corrosion process.

Voltage: during oxidation, the voltage should be increased slowly and too quickly, which may cause current concentration at the non-uniform site of the newly formed oxide film, resulting in severe electrical breakdown at the site, causing corrosion of metallic titanium, and the voltage is preferably 15-20V.

Temperature: the temperature is increased, the film layer is thinned, if the thickness of the film can be increased at higher temperature, the optimal temperature is 25-35 ℃, preferably 30 °c ^o C。

(d) The etching process is the key content of the invention, and is mainly aimed at etching titanium oxide to expose carbon nano tubes coated in titanium oxide, in addition, the etching solution is pure tartaric acid etching solution, if nitric acid, hydrochloric acid, sulfuric acid or oxalic acid and citric acid are used in the same concentration, the etching effect of the etching solution can not effectively expose carbon nano tubes, and the etching effect can be related to the self property of tartaric acid, and the specific principle is to be studied, and the main aim of etching the exposed carbon nano tubes is to (1) effectively improve Ti/TiO ₂ The conductivity of the CNT is poor, the pure titanium oxide is unfavorable for the subsequent electrodeposition of lead oxide, and the addition of the CNT effectively improves the conductivity of the material;(2) In the subsequent electrodeposition process of lead oxide, the carbon nano tube can also deposit lead oxide to play a role similar to stitching, and when the lead oxide is peeled off from the surface of titanium oxide, the carbon nano tube can play a role of stitching reinforcement and can effectively prolong the service life of anode materials, and the stitching role is similar to that of Ti/TiO ₂ -CNT/α-PbO ₂ /β-PbO ₂ Is indispensable for long life performance, as shown in the schematic diagram of figure 2, the carbon nano tube can effectively stitch the lead oxide and the titanium oxide.

In addition, it should be noted that the semiconductor properties of titanium dioxide make it very resistant to itself, unsuitable for electroplating the intermediate layer, while the incorporation of carbon nanotubes in the anodized film only partially improves the conductivity of the substrate, if titanium oxide substrates with high conductivity are to be obtained, the etched Ti/TiO may be optionally treated ₂ -subjecting the CNT material to a reductive activation treatment, in particular by subjecting said Ti/TiO ₂ CNT is set as cathode, voltage is applied so that Ti/TiO ₂ More free charges are generated in the CNT, so that the conductivity of the CNT is enhanced, and in the process, an ammonium sulfate solution is used as an electrolyte, and a reduction event is controlled to be within 1min, so that a bottom layer with good conductivity can be obtained.

(e) Electrodepositing lead oxide:

principle of: anode Pb ²⁺ +2H ₂ O→PbO ₂ +4H ⁺ +2e;2H ₂ O→O ₂ +4H ⁺ +4e (side reaction)

Cathode Pb ²⁺ +2e→Pb;2H ⁺ +2e→H ₂

The pH value of the electrodeposition liquid, the temperature of the electrodeposition liquid, the current density, the composition of the electroplating liquid, and the like are all influencing factors of the electrodeposition method.

In Ti/beta-Pb 0 ₂ The electrode adds an intermediate layer in order to enhance the bonding firmness of the beta Pb02 plating layer and the titanium substrate and to alleviate the electrodeposition distortion of the surface plating layer. Due to Pb ⁴ The +ion radius is large, and the layers are all isomorphous oxides, so that the matching property between the layers is poor, and the bonding performance is poor. Thus, the experiment adopts the absence of electrodeposition stressAs an intermediate layer to mitigate electrodeposition distortion and to make the surface layer uniformly distributed. The intermediate layer is prepared by electrodepositing alpha-Pb 02 under alkaline conditions.

Acidity: the alpha-PbO is distinguished from the beta-type according to the crystal type ₂ The alloy is an orthorhombic system, has small size and structure of crystal grains and strong binding force, but has poor conductivity and relatively good stability, and is generally obtained from alkaline lead electroplating solution; beta-PbO 2 is tetragonal, has relatively large grain size and porous loose structure, and has resistivity of 96 [ mu ] ohm-cm, and is generally obtained from acid lead electroplating solution. The pH is generally controlled to about 10-12 when alpha-Pb 02 is present, beta-Pb 0 ₂ The pH is generally controlled to be about 1-2, and when the pH is too small, the electrode surface active layer becomes brittle, the mechanical property is weakened, and the service life of the electrode is influenced: the pH is too high, and the precipitation of cathode lead ions is serious.

Temperature: tests have shown that, over a range of temperatures, the higher the temperature, the less internal stress in the coating and the better the mechanical properties of the plated electrode, which may be related to the crystalline structure of the electrodeposited layer, since the heating treatment helps to adjust the ion position inside the crystal to eliminate the internal stress. However, the temperature is too high, which leads to Pb0 in the matrix ₂ Oxidation occurs before deposition to form an oxide film with uneven surface resistance distribution, resulting in Pb0 ₂ Are not uniformly deposited on the substrate, and thus the optimal electrodeposition temperature for different substrates is dependent on the situation.

Current density: constant current methods are commonly used because the electrodeposition rate is too slow and the grains are coarse and the real surface area is small. At high current densities, a majority of α -PbO2 is obtained, and at low current densities, a majority of β -PbO is obtained ₂ 。

As shown in fig. 4: deposited alpha-PbO ₂ The particle size is more uniform and the surface of the coating becomes smoother, which may enhance the surface activity of beta-PbO ₂ Binding force of the plating layer; the surface is smoother, and the oxygen evolution electrocatalytic activity of the electrode can be improved.

As shown in fig. 5: surface active layer beta-PbO ₂ Takes on a pyramid shape and is uniformly rugged, which can enable the electrodeThe surface contact reaction activity area is increased, the surface is more and more rugged, the activation area of the electrode surface can be increased, and more active surface area participates in the reaction, thereby being beneficial to improving the electrocatalytic activity of the electrode, and in short, the prepared beta-PbO ₂ The surface of the layer is more rugged, so that the area of the beta-PbO 2 coating participating in the reaction is greatly increased, and the oxygen evolution electrocatalytic activity of the electrode is improved, which is very important.

Based on the above, and as shown in fig. 1, the specific process of the present invention is as follows:

(1) A titanium or titanium alloy metal substrate is provided and pretreated to expose the metal substrate and obtain a roughened metal surface, as shown in fig. 1 (a).

(2) Preparing an anodic oxidation solution containing carbon nanotubes, and forming an anodic oxidation film on the surface of the metal substrate by anodic oxidation, wherein the inside of the anodic oxidation film is coated with the carbon nanotubes, as shown in the figure 1 (b)

(3) Removing part of the anodic oxide film by tartaric acid etching to expose the carbon nanotubes, as shown in fig. 1 (c);

(4) Alpha-lead oxide is obtained by anodic alkaline electrodeposition and beta-lead oxide is obtained by acidic electrodeposition.

(5) Obtaining high-life Ti/TiO ₂ -CNT/α -lead oxide/β -lead oxide anode as shown in fig. 1 (d).

The beneficial technical effects are as follows:

(1) The surface of the titanium base is etched into an uneven rough surface by polishing, alkali etching and acid washing so as to increase the real surface area of the titanium base, thus the bonding force between the active coating and the base is enhanced, the mechanical bonding degree is improved, and the service life of the coating is prolonged.

(2) The carbon nano tube treated by mixed acid is uniformly mixed with electrolyte, and a titanium oxide film and carbon nano tube composite oxide layer is obtained in one step, and the binding force of the titanium oxide and the carbon nano tube is strong.

(3) The special tartaric acid has good effect of corroding the anodic oxide film, and after the carbon nano tube is exposed, ti/TiO ₂ CNT material as anodeThe conductivity is enhanced, and the conductive material can be used as a deposition site of lead oxide to effectively improve the subsequent Ti/TiO ₂ -lifetime of CNT/α -lead oxide/β -lead oxide anode.

(4) And adjusting proper voltage and current density to obtain the high-activity beta-lead oxide anode.

(5) The invention has high efficiency of degrading phenol wastewater by electrocatalytic oxidation, good stability in the degradation process, 84.1 for phenol removal rate, 66.3% for COD removal rate within 100min and high degradation efficiency.

Drawings

Fig. 1 is a schematic view of the preparation process of the anode material of the present invention.

FIG. 2 is a schematic diagram of anodic oxide film and α - β -lead oxide active surface CNT stitching according to the present invention.

FIG. 3 is an SEM image of a titanium metal substrate of the present invention after pickling.

Fig. 4 is an SEM image of the α -lead oxide of the present invention.

Fig. 5 is an SEM image of beta-lead oxide of the present invention.

FIG. 6 is an LSV curve of the anode electrode of example 2 of the present invention.

FIG. 7 is a graph showing the removal rate of degraded phenol from the anode material according to example 2 of the present invention.

FIG. 8 is a graph showing the removal rate of COD of the anode material of example 2.

Detailed Description

Example 1

The preparation method of the anode material for degrading the high-efficiency phenol wastewater comprises the following preparation steps:

(1) Providing a titanium or titanium alloy metal substrate, and carrying out pretreatment on the metal substrate, wherein the pretreatment comprises mechanical polishing, alkali washing and acid washing, wherein the polishing is sequentially carried out by using 300-mesh sand paper and 800-mesh sand paper, then deionized water is used for washing, and the alkali washing is a mixed aqueous solution of 10g/L sodium carbonate, 10g/L trisodium phosphate, 10g/L sodium silicate and 1g/L octyl phenol polyoxyethylene ether, and the temperature is 40 ^o C, the time is 10min,

pickling is a composite pickling solution of 2wt.% oxalic acid and 1wt.% hydrochloric acid, and the pickling temperature is 50 ^o C, time ofAfter 30min, the washing is carried out for many times by using deionized water.

(2) Preparing an anodic oxidation solution containing carbon nano tubes, wherein the anodic oxidation solution is prepared from 4g/L ammonium fluoride, 300ml ethylene glycol and 50ml of an aqueous solution of 0.15wt.% of acidized carbon nano tubes, the diameter of each carbon nano tube is 50-70nm, the length of each carbon nano tube is 5-8 mu m, and the acidized carbon nano tubes are prepared by the following steps: placing carbon nano tube in three-mouth flask, passing through 100 ^o C, acidifying mixed acid, and carrying out reflux treatment on cooling water for 5H, wherein the mixed acid is 98wt.% H with the volume ratio of 2.5:1 ₂ SO ₄ And 65% -67wt.% HNO ₃ And (5) mixing acid.

(3) Taking the metal substrate pretreated in the step (1) as an anode, taking the anode oxidizing solution configured in the step (2) as an electrolyte, performing anode oxidation treatment on the substrate, forming an anode oxide film on the surface of the metal substrate, wherein the inside of the anode oxide film is coated with carbon nano tubes, the anode oxidation voltage is 15V, and the reaction time is 60min.

(4) Removing part of the anodic oxide film by chemical corrosion to expose the carbon nano tube; the chemically etched solution was 5wt.% tartaric acid, the etching time was 10min, the temperature was 40 ^o C。

(5) Washing with deionized water to obtain Ti/TiO ₂ -CNT material.

(6) Preparing alkaline lead electrodeposition liquid; the alkaline lead electrodeposition liquid comprises 15-20g/L lead oxide and 100g/L sodium hydroxide.

(7) Ti/TiO as obtained in step (5) ₂ The CNT material is used as anode, the platinum sheet is used as cathode, and Ti/TiO is obtained by electrolysis ₂ -CNT/α -lead oxide material, deionized and washed a plurality of times; the electrolysis parameters were as follows: the current density was 30mA/cm ² Temperature 30 ^o C, the time is 40min, and the distance between the polar plates is 1.5cm.

(8) Preparing an acidic lead electrodeposition liquid; pb (NO) in the lead electrodeposit solution of 0.45mol/L ₃ ) ₂ NaF of 0.01mol/L and proper HNO ₃ The pH of the electrolyte was adjusted to 1 using tartaric acid.

(9) Ti/TiO as obtained in step (7) ₂ The CNT/alpha-lead oxide material is taken as an anode, a platinum sheet is taken as a cathode, and the anode is prepared by electrolysisObtaining Ti/TiO ₂ -CNT/α -lead oxide/β -lead oxide material, electrodeposited for 1.0h at 40 ℃ with an electrodeposited current density of 10mA/cm ² The distance between the polar plates is 3cm.

Example 2

(1) Providing a titanium or titanium alloy metal substrate, and carrying out pretreatment on the metal substrate, wherein the pretreatment comprises mechanical polishing, alkali washing and acid washing, the polishing is sequentially carried out by using 300-mesh sand paper and 800-mesh sand paper, then deionized water is used for washing, the alkali washing is a mixed aqueous solution of 15g/L sodium carbonate, 15g/L trisodium phosphate, 15g/L sodium silicate and 1.5g/L octyl phenol polyoxyethylene ether, and the temperature is 15 ^o C, the time is 12.5min,

composite pickling solution with 2.5 wt.% oxalic acid and 1.25wt.% hydrochloric acid and pickling temperature of 55 ^o C, the time is 35min, and the washing is carried out for a plurality of times by using deionized water after the acid washing.

(2) Preparing an anodic oxidation solution containing carbon nano tubes, wherein the anodic oxidation solution is prepared from 4.5g/L ammonium fluoride, 400ml ethylene glycol and 55ml of an aqueous solution of 0.175wt.% of acidized carbon nano tubes, the diameter of each carbon nano tube is 50-70nm, the length of each carbon nano tube is 5-8 mu m, and the acidized carbon nano tubes are prepared by the following steps: placing carbon nano tube in three-mouth flask, passing through 100 ^o C, acidifying mixed acid, and carrying out reflux treatment on cooling water for 5H, wherein the mixed acid is 98wt.% H with the volume ratio of 2.5:1 ₂ SO ₄ And 65% -67wt.% HNO ₃ And (5) mixing acid.

(3) Taking the metal substrate pretreated in the step (1) as an anode, taking the anode oxidizing solution configured in the step (2) as an electrolyte, performing anode oxidation treatment on the substrate, forming an anode oxide film on the surface of the metal substrate, wherein the inside of the anode oxide film is coated with carbon nano tubes, the anode oxidation voltage is 17.5V, and the reaction time is 90min.

(4) Removing part of the anodic oxide film by chemical corrosion to expose the carbon nano tube; the chemically etched solution was 10wt.% tartaric acid, the etching time was 12.5min, the temperature was 45 ^o C。

（5）Washing with deionized water to obtain Ti/TiO ₂ -CNT material.

(6) Preparing alkaline lead electrodeposition liquid; the alkaline lead electrodepositing solution comprises 27.5g/L lead oxide and 110g/L sodium hydroxide.

(7) Ti/TiO as obtained in step (5) ₂ The CNT material is used as anode, the platinum sheet is used as cathode, and Ti/TiO is obtained by electrolysis ₂ -CNT/α -lead oxide material, deionized and washed a plurality of times; the electrolysis parameters were as follows: the current density was 40mA/cm ² Temperature 32.5 ^o C, the time is 45min, and the distance between the polar plates is 1.75cm.

(8) Preparing an acidic lead electrodeposition liquid; pb (NO) in the lead electrodeposit solution of 0.45mol/L ₃ ) ₂ NaF of 0.01mol/L and proper HNO ₃ The pH of the electrolyte was adjusted to 1.5 using tartaric acid.

(9) Ti/TiO as obtained in step (7) ₂ The CNT/alpha-lead oxide material is used as an anode, a platinum sheet is used as a cathode, and Ti/TiO is obtained by electrolysis ₂ -CNT/α -lead oxide/β -lead oxide material, electrodeposited for 1.25h at 45 ℃ with an electrodeposited current density of 12.5mA/cm ² The distance between the polar plates is 3.5cm.

Example 3

(1) Providing a titanium or titanium alloy metal substrate, and carrying out pretreatment on the metal substrate, wherein the pretreatment comprises mechanical polishing, alkali washing and acid washing, wherein the polishing is sequentially carried out by using 300-mesh sand paper and 800-mesh sand paper, then deionized water is used for washing, and the alkali washing is a mixed aqueous solution of 20g/L sodium carbonate, 20g/L trisodium phosphate, 20g/L sodium silicate and 2g/L octyl phenol polyoxyethylene ether, and the temperature is 50 ^o C, the time is 15min,

composite pickling solution with 3wt.% oxalic acid and 1.5wt.% hydrochloric acid and pickling temperature of 60% ^o C, the time is 40min, and the washing is carried out for many times by using deionized water after the acid washing.

(2) Preparing an anodic oxidation solution containing carbon nano tubes, wherein the anodic oxidation solution is an aqueous solution 60m of 5g/L ammonium fluoride, 300-500ml ethylene glycol and 2wt.% of acidized carbon nano tubesl, the pipe diameter of the carbon nano-tube is 50-70nm, the length is 5-8 mu m, and the acidification treatment process of the carbon nano-tube is as follows: placing carbon nano tube in three-mouth flask, passing through 100 ^o C, acidifying mixed acid, and carrying out reflux treatment on cooling water for 5H, wherein the mixed acid is 98wt.% H with the volume ratio of 2.5:1 ₂ SO ₄ And 65% -67wt.% HNO ₃ And (5) mixing acid.

(3) Taking the metal substrate pretreated in the step (1) as an anode, taking the anode oxidizing solution configured in the step (2) as an electrolyte, performing anode oxidation treatment on the substrate, forming an anode oxide film on the surface of the metal substrate, wherein the inside of the anode oxide film is coated with carbon nano tubes, the anode oxidation voltage is 20V, and the reaction time is 120min.

(4) Removing part of the anodic oxide film by chemical corrosion to expose the carbon nano tube; the chemically etched solution was 15wt.% tartaric acid, the etching time was 15min, the temperature was 50 ^o C。

(5) Washing with deionized water to obtain Ti/TiO ₂ -CNT material.

(6) Preparing alkaline lead electrodeposition liquid; the alkaline lead electrodepositing liquid comprises 20g/L lead oxide and 120g/L sodium hydroxide.

(7) Ti/TiO as obtained in step (5) ₂ The CNT material is used as anode, the platinum sheet is used as cathode, and Ti/TiO is obtained by electrolysis ₂ -CNT/α -lead oxide material, deionized and washed a plurality of times; the electrolysis parameters were as follows: the current density was 50mA/cm ² Temperature 35 ^o And C, the time is 50min, and the distance between the polar plates is 2cm.

(8) Preparing an acidic lead electrodeposition liquid; pb (NO) in the lead electrodeposit solution of 0.45mol/L ₃ ) ₂ NaF of 0.01mol/L and proper HNO ₃ The pH of the electrolyte was adjusted to 2 using tartaric acid.

(9) Ti/TiO as obtained in step (7) ₂ The CNT/alpha-lead oxide material is used as an anode, a platinum sheet is used as a cathode, and Ti/TiO is obtained by electrolysis ₂ -CNT/α -lead oxide/β -lead oxide material, electrodeposited for 1.5h at 50 ℃ with an electrodeposited current density of 15mA/cm ² The distance between the polar plates is 4cm.

The samples prepared as described in example 2 were tested for electrocatalytic activity.

(1) Linear LSV test: operating parameters: the voltage range is 1.0-2.2V, the sweeping speed is 100mV/s, and the solution is 0.1M sodium sulfate.

Linear Sweep Voltammetry (LSV) is a conventional method of studying the oxygen evolution overpotential of electrodes as they undergo electrocatalytic oxidation. In the electro-oxidation of organic waste water, side reactions may occur at the anode resulting in the production of oxygen, which cannot be used either

Degradation of organic matter causes loss of electric energy, resulting in reduced efficiency in degrading organic wastewater. The higher oxygen evolution potential means that the oxygen evolution side reaction is more difficult to occur in the hydroxyl radical, and the oxygen evolution side reaction is the main competition reaction of the hydroxyl radical in the mineralization process of the organic pollutant, so that the effective utilization rate of the hydroxyl radical is improved, and the electrode plate has higher catalytic activity, so that the oxygen evolution overpotential of an anode material with excellent catalytic performance is enough to be large in the degradation process of the organic wastewater, thereby the oxygen evolution side reaction can not occur when the organic wastewater is oxidized under a certain voltage, and the degradation efficiency is improved. As shown in the linear sweep voltammetric curve LSV of FIG. 6, ti/TiO ₂ The oxygen uptake overpotential of the CNT/alpha-lead oxide/beta-lead oxide electrode was 1.81V, and furthermore, the oxidation peak potential of phenol on the electrode was 0.69V, the peak current density was 0.51mA/cm ² The difference between the oxygen evolution potential and the phenol electrocatalytic oxidation potential is 1.12V

Fully shows that the high peroxy potential is easy to generate more strong oxidant or hydroxyl free radical in the degradation process, thereby being beneficial to improving the efficiency of degrading organic wastewater.

(2) And (3) degradation phenol test: the sample of example 2 was used as anode, titanium plate as cathode, the distance was controlled to 1.5cm, and the reaction temperature was 40 ^o C，30mA/cm ² The concentrations of phenol at different degradation times were tested by an ultraviolet spectrophotometer and calculated by the following formula:

wherein C is ₀ For initial phenol concentration, C _t Phenol after time tConcentration, while detecting a change in the amount of organic carbon, as shown in the following formula

Wherein, TOC ₀ TOC for the initial phenol content of organic carbon _t Is the concentration of the organic carbon after the time t,

as shown in fig. 7 and 8, at 40 ^o C，30mA/cm ² And (3) after the anode is used for simulating phenol wastewater degradation for 100min, the phenol removal rate is 84.1, and the COD removal rate is 66.3%.

(3) Life test:

the electrode prepared in example 2 was used as an anode, a copper plate was used as a cathode, the electrode spacing was 10mm, and the electrode was measured at 60℃and 1.0mol/L H ₂ SO ₄ In the aqueous solution, the current density increased from zero by 0.5A/cm per minute ² Until the current density is 4.0A/cm ² A constant current density of 4.0A/cm ² The test was conducted with an initial cell voltage of about 4.5V, and when the operating voltage increased to 10V, it was used as a criterion for evaluating the deactivation of the electrode, and the electrolysis time at this time was the life of the electrode.

Thermal shock experimental conditions: yang Ping initial test temperature was 140 ℃, the electrodes were placed in a muffle furnace for 10 minutes, removed and quickly placed in water at 20 ℃, after the muffle furnace was raised by 20 ℃, the electrodes were placed in the muffle furnace and calcined until the coating damaged the exposed substrate.

The time of breakdown voltage generation in the embodiment 2 of the invention is 387h respectively, and the time is converted into 4.25 years of industrial service life, thereby reaching the industrial use standard.

The thermal shock end point temperature of example 2 of the present invention was 290 ℃, which corresponds to the electrode life.

Although the present invention has been described by way of example with reference to the preferred embodiments, the present invention is not limited to the specific embodiments, and may be modified appropriately within the scope of the present invention.

Claims

1. The preparation method of the anode material for degrading the high-efficiency phenol wastewater is characterized by comprising the following steps of:

(2) Preparing an anodic oxidation solution containing carbon nanotubes, wherein the carbon nanotubes are subjected to acidification treatment, and the acidification process is as follows: placing the carbon nano tube in a three-neck flask, acidizing by mixed acid at 100 ℃, and carrying out reflux treatment on cooling water for 5H, wherein the mixed acid is 98wt.% H with the volume ratio of 2.5:1 ₂ SO ₄ And 65% -67wt.% HNO ₃ Mixing acid;

(3) Taking the metal substrate pretreated in the step (1) as an anode, taking the anode oxidizing solution configured in the step (2) as an electrolyte, performing anodic oxidation treatment on the metal substrate, forming an anodic oxide film on the surface of the metal substrate, and coating carbon nano tubes inside the anodic oxide film;

the anodic oxidation solution is 50-60ml of aqueous solution of 4-5g/L ammonium fluoride, 300-500ml ethylene glycol and 0.15-2 wt.% acidized carbon nano tube, the voltage is 15-20V, the reaction time is 60-120 min, the tube diameter of the carbon nano tube is 50-70nm, and the length is 5-8 mu m;

(4) Removing part of the anodic oxide film by chemical corrosion to expose the carbon nano tube: 5-15wt.% tartaric acid is used as a solution for chemical corrosion, the corrosion time is 10-15min, and the temperature is 40-50 ℃;

(5) Washing with deionized water to obtain Ti/TiO ₂ -CNT material;

(6) Preparing alkaline lead electrodeposition liquid which comprises 15-20g/L lead oxide and 100-120g/L sodium hydroxide;

(7) Ti/TiO as obtained in step (5) ₂ The CNT material is used as anode, the platinum sheet is used as cathode, and Ti/TiO is obtained by electrolysis ₂ -CNT/α -lead oxide material, deionized, washed multiple times, electrolysis parameters were as follows: the current density is 30-50mA/cm ² The temperature is 30-35 ℃, the time is 40-50min, and the distance between the polar plates is 1.5-2cm;

(8) Preparing an acidic lead electrodeposition liquid: acidic lead electrodeposition liquid: 0.45 mol-Pb (NO) of L ₃ ) ₂ NaF of 0.01mol/L and proper HNO ₃ Adjusting the pH of the electrolyte to 1-2 by using tartaric acid;

(9) Ti/TiO as obtained in step (7) ₂ The CNT/alpha-lead oxide material is used as an anode, a platinum sheet is used as a cathode, and Ti/TiO is obtained by electrolysis ₂ -CNT/alpha-lead oxide/beta-lead oxide material, wherein the electrodeposition time is 1.0-1.5h, the deposition temperature is 40-50 ℃, and the electrodeposition current density is 10-15mA/cm ² The distance between the polar plates is 3-4cm.

2. The method for preparing the anode material for degrading the high-efficiency phenol wastewater, as claimed in claim 1, wherein the pretreatment in the step (1) comprises mechanical polishing, alkali washing and acid washing, wherein the polishing is sequentially carried out by using 300-mesh sand paper and 800-mesh sand paper for polishing, then deionized water washing is carried out, the alkali washing is a mixed aqueous solution of 10-20g/L sodium carbonate, 10-20g/L trisodium phosphate, 10-20g/L sodium silicate and 1-2g/L octyl phenol polyoxyethylene ether, the temperature is 40-50 ℃, the time is 10-15min, the acid washing is a composite acid washing solution of 2-3wt.% oxalic acid and 1-1.5wt.% hydrochloric acid, the acid washing temperature is 50-60 ℃, the time is 30-40min, and deionized multiple washing is used after the acid washing.

3. The method for preparing an anode material for efficient phenol wastewater degradation according to claim 1, characterized in that for enhancing Ti/TiO ₂ Conductivity of CNT after step (4) and before step (5), for Ti/TiO ₂ -the CNT material is subjected to a cathodic electrochemical reduction treatment.