A porous electrocatalytic anode material and its preparation method and application

Abstract

The present invention discloses a porous electrocatalytic anode material and a preparation method and application thereof, belonging to the technical field of wastewater treatment, and comprising the following steps: applying a coating liquid on a titanium metal substrate treated with inorganic acid immersion by multiple coatings, and performing a programmed temperature rise treatment under an inert atmosphere after each coating to obtain the porous electrocatalytic anode material; the coating liquid contains transition metal ions, polycarboxylic acids and polyhydroxy organic porous materials; the transition metal ions include first transition metal ions and second transition metal ions, the first transition metal ions include one or more of iron, cobalt, nickel, copper or zinc ions, and the second transition metal ions include ruthenium and iridium ions. The electrocatalytic anode material prepared by the method has strong acid and alkali corrosion resistance, large catalytic contact area, abundant catalyst exposure sites, high conductivity, and high electrocatalytic oxidation efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, and in particular relates to a porous electrocatalytic anode material and a preparation method and application thereof. Background Art

[0002] The treatment of industrial organic wastewater is a major problem faced in pharmaceutical and chemical production. The pollutant composition of this type of wastewater is relatively complex, and the content of various substances in the water body varies greatly. There are many problems in the treatment process of this type of wastewater. If this type of wastewater is not treated properly or is not treated up to standard, it will not only affect industrial production, but also seriously pollute the ecological environment. Therefore, it is necessary to develop new catalysts for the treatment of organic wastewater.

[0003] At present, the main methods for treating organic wastewater are Fenton oxidation, wet oxidation, biochemical method, physical adsorption, electrocatalytic oxidation, and photocatalytic oxidation. Although these methods have been widely used in industry, they still face many problems. Fenton oxidation is the most common method. Although this method has certain cost advantages in treating high-concentration organic wastewater, its efficiency in treating complex organic wastewater is not high, and it will also produce a large amount of secondary pollutants such as iron mud. The large amount of sulfate introduced during the treatment process will also produce sulfur-containing toxic gases such as hydrogen sulfide in the subsequent biochemical treatment. Although the wet oxidation method has a high treatment efficiency, the treatment conditions are strict, which is not only costly but also has certain safety hazards. Although the biochemical method has a low cost in treating organic wastewater, complex organic wastewater must be pretreated before entering the biochemical system, and the biochemical treatment efficiency of complex organic matter is low. Although the electrocatalytic oxidation method is simple to treat and has no secondary pollution, the anode materials that can be selected are relatively limited. The shortage of high-efficiency electrocatalytic anode materials limits the large-scale application of this method in industry.

[0004] Therefore, it is necessary to develop high-efficiency electrocatalytic plates for electrocatalytic oxidation treatment of organic wastewater. Currently, most of the electrocatalytic anodes used in the market are titanium series coating materials. Although this type of material is relatively stable, the catalytic oxidation efficiency needs to be further improved. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the above background technology and provide a porous electrocatalytic anode material and a preparation method and application thereof to improve the catalytic oxidation efficiency.

[0006] In order to solve the above technical problems, the technical solution proposed by the present invention is:

[0007] A method for preparing a porous electrocatalytic anode material comprises the following steps:

[0008] The porous electrocatalytic anode material is prepared by coating the coating liquid on the titanium metal substrate treated by immersion in inorganic acid by multiple coatings, and performing a programmed temperature rise treatment in an inert atmosphere after each coating.

[0009] The coating liquid contains transition metal ions, polycarboxylic acids and polyhydroxy organic porous materials;

[0010] The transition metal ions include first transition metal ions and second transition metal ions, the first transition metal ions include one or more of iron, cobalt, nickel, copper or zinc ions, and the second transition metal ions include ruthenium and iridium ions;

[0011] The polyhydroxy organic porous material is COF-BTA-DHBZ;

[0012] The programmed temperature increase is to first increase the temperature to a first temperature to volatilize the solvent in the coating liquid, and then increase the temperature to a second temperature to carbonize the polyhydroxy organic porous material.

[0013] As a further improvement, the inorganic acid includes one or more of hydrochloric acid, nitric acid, phosphoric acid or sulfuric acid, the inorganic acid immersion treatment time is 12-24h, and the treatment temperature is 50-80°C.

[0014] As a further improvement, the amount of the first transition metal ion is 3-5 g / 1 m 2 Titanium metal matrix, the amount of ruthenium ions is 5-15 g / 1m 2 Titanium metal matrix, the dosage of iridium ions is 3-5 g / 1m 2 Titanium metal base.

[0015] As a further improvement, the polycarboxylic acid includes one or more of citric acid, oxalic acid, succinic acid, adipic acid, azelaic acid or sebacic acid, and the amount of the polycarboxylic acid used is 1.5-3 times the mass of the transition metal ion.

[0016] As a further improvement, the amount of the polyhydroxy organic porous material is 1.5-3 times the mass of the transition metal ions.

[0017] As a further improvement, the multiple coatings are applied 15-20 times.

[0018] As a further improvement, the first temperature is 110-130° C., and the temperature is increased to the first temperature at a heating rate of 4-8° C. per minute and maintained for 1-3 hours.

[0019] As a further improvement, the second temperature is 800-1200° C., and the temperature is increased to the second temperature at a heating rate of 3-6° C. per minute and maintained for 3-6 hours.

[0020] The invention also provides a porous electrocatalytic anode material, which is prepared by adopting the method.

[0021] The present invention also provides an application of the porous electrocatalytic anode material in electrocatalytic oxidation of organic wastewater.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention uses transition metals (including ruthenium and iridium) as catalysts and polycarboxylic acids as metal ion coordination agents and dispersants. The metal ions of the coating are evenly dispersed on the surface of the substrate through the dispersing effect of the polycarboxylic acids. A polyhydroxy organic porous material is used as a pore-forming agent. The coordination of the polyhydroxy organic porous material with metal ions and the method of programmed temperature rise are used to obtain a coating structure with rich pores and uniform pore distribution, thereby preparing a porous electrocatalytic titanium coating anode material with uniform metal dispersion. The electrocatalytic anode material prepared by this method has strong acid and alkali corrosion resistance, a large catalytic contact area, abundant catalyst exposure sites, high conductivity, and high electrocatalytic oxidation efficiency.

[0024] The anode material of the present invention can be applied to the electrocatalytic oxidation treatment of various pharmaceutical and chemical organic wastewaters. When the COD of the chemical and pharmaceutical wastewater is less than 1000 mg / L, the COD can be reduced by more than 80%, and the catalytic oxidation efficiency is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 It is the structure of polyhydroxy organic porous material. DETAILED DESCRIPTION

[0027] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and meticulously below in conjunction with the accompanying drawings and preferred embodiments of the present invention, but the protection scope of the present invention is not limited to the following specific embodiments.

[0028] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0029] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0030] In some specific embodiments, the method for preparing the porous electrocatalytic anode material of the present invention comprises the following steps:

[0031] The coating liquid is coated on a titanium metal substrate soaked in an inorganic acid by multiple coatings, and a programmed temperature rise treatment is performed in an inert atmosphere after each coating to form a porous coating on the titanium metal substrate to obtain an electrocatalytic anode material.

[0032] In some embodiments, the titanium metal substrate is a titanium metal plate or a titanium metal mesh. The inorganic acid can be one or more of hydrochloric acid, nitric acid, phosphoric acid or sulfuric acid, the concentration of the inorganic acid is 10-30wt%, the acid treatment time is 12-24h, and the acid treatment temperature is 50-80°C. The corrosiveness of the inorganic acid is used to treat the substrate to increase the roughness of the titanium substrate surface to facilitate the loading of the metal.

[0033] The coating liquid contains transition metal ions, polycarboxylic acids, and polyhydroxy organic porous materials. The solvent of the coating liquid is preferably n-butanol.

[0034] In some embodiments, the transition metal ions include a first transition metal ion and a second transition metal ion, the first transition metal ion includes one or more of iron, cobalt, nickel, copper, zinc ions (preferably iron and cobalt), and the second transition metal ions include ruthenium and iridium ions. The first transition metal ion is added in the form of its chloride, sulfate, nitrate, or acetate, preferably chloride. The second transition metal ion is added in the form of its chloride. The amount of the first transition metal ion is 3-5 g / 1m 2 Titanium metal matrix, the amount of ruthenium metal is 5-15 g / 1m 2 Titanium metal matrix, the amount of iridium metal is 3-5 grams / 1m 2 Titanium metal substrate. The transition metal ion concentration in the coating solution is 3-5wt%.

[0035] In the electrocatalytic oxidation of organic wastewater, both the first transition metal and the second transition metal have catalytic effects. The first transition metal further improves the catalytic performance. Ruthenium and iridium can also improve conductivity and increase stability. The electrode is more corrosion-resistant and has a longer service life.

[0036] In some embodiments, the polycarboxylic acid may include one or more of citric acid, oxalic acid (oxalic acid), succinic acid, adipic acid, azelaic acid, and sebacic acid. The amount of the polycarboxylic acid may be 1.5-3 times the amount of the transition metal ion. Before use, the polycarboxylic acid and the metal salt are dissolved together in n-butanol.

[0037] In some embodiments, the polyhydroxy organic porous material is COF-BTA-DHBZ, and its structure is as follows: Figure 1 , which is a polyhydroxy covalent organic framework material connected by imine bonds. The amount of the polyhydroxy organic porous material is 1.5-3 times the amount of the transition metal ion. Before use, the polyhydroxy organic porous material is evenly dispersed with a n-butanol solution of a polycarboxylic acid and a metal salt by ball milling.

[0038] Polycarboxylic acids act as metal ion ligands, and polyhydroxy organic porous materials also coordinate with metal ions. The coordination effect makes the metal ions disperse more evenly on the electrode surface, greatly improving the conduction between electrons and the formation of catalytic active centers.

[0039] The polyhydroxy organic porous material is used as a pore-forming agent. The COF-BTA-DHBZ used has a rich pore structure inside, which helps to generate a pore structure on the electrode surface, greatly increasing the specific surface area of ​​the electrode. The larger specific surface area can fully expose the catalytic sites and thus improve the catalytic efficiency.

[0040] In some embodiments, the number of coatings is 15-20 times, and each coating is applied on the thin coating formed by the previous coating. The process of programmed temperature rise is: after each coating, the temperature is first raised to 110-130°C at a rate of 4-8°C per minute, maintained for 1-3 hours, and then raised to 800-1200°C at a rate of 3-6°C per minute, maintained for 3-6 hours. Thus, a porous transition metal-doped ruthenium-iridium-titanium coating is formed on the surface of the titanium metal substrate, and a porous electrocatalytic titanium coating anode material with uniform metal dispersion is obtained.

[0041] The temperature is first raised to 110-130°C to allow the solvent in the coating liquid to evaporate slowly and completely to ensure the stability of the coating. The temperature is then raised to 800-1200°C to carbonize the polyhydroxy organic porous material and produce more porous structures. Therefore, programmed temperature rise helps to form more porous structures. However, if the heating rate is too fast, the structure will collapse, which is not conducive to the formation of the porous structure. Therefore, the heating rate needs to be controlled within the above range.

[0042] In the application of electrocatalytic oxidation of organic wastewater, a titanium plate or an iron plate is used as a cathode, and the anode material prepared by the present invention is used as an anode. By adjusting the current, the plate spacing, the electrolysis time, and the wastewater pH, the electrocatalytic oxidation reduces the COD, thereby evaluating the catalytic activity of the anode material. In some embodiments, the plate spacing is 2-4 cm, the current density is 200-500 A / m 2 , the wastewater pH is 2-12.

[0043] Example 1

[0044] 0.01m 2The metal titanium plate was soaked in a 20 wt % sulfuric acid aqueous solution at 80° C. for 12 h, and then dried in an oven at 80° C. for 2 h for later use.

[0045] A mixture of chloride salts of iron, cobalt, ruthenium and iridium (containing 0.03g of iron ions, 0.02g of cobalt ions, 0.1g of ruthenium ions and 0.05g of iridium ions) was placed in 5g of n-butanol solution and heated to completely dissolve, and then 0.3g of oxalic acid was added, and 0.3g of polyhydroxy organic porous material COF-BTA-DHBZ was dispersed in the above solution by ball milling to prepare a coating liquid. The above coating liquid was applied to a titanium plate treated with sulfuric acid for 15 times, and after each application, the temperature was raised to 120°C at a rate of 5°C per minute in a nitrogen atmosphere, maintained for 1h, and then raised to 1000°C at a rate of 5°C per minute, maintained for 3h, to obtain a porous transition metal doped ruthenium iridium titanium coating electrocatalytic anode plate.

[0046] Example 2

[0047] The difference from Example 1 is that the transition metal ions are different:

[0048] A mixture of chloride salts of nickel, cobalt, ruthenium and iridium (containing 0.02 g of nickel ions, 0.02 g of cobalt ions, 0.1 g of ruthenium ions and 0.05 g of iridium ions) was placed in 5 g of n-butanol solution and heated to completely dissolve it.

[0049] The other steps and parameters are the same as those in Example 1.

[0050] Example 3

[0051] The difference from Example 1 is that citric acid is used instead of oxalic acid.

[0052] Comparative Example 1

[0053] The difference from Example 1 is that no iron ions and cobalt ions are added.

[0054] Comparative Example 2

[0055] The difference from Example 1 is that no ruthenium ions and iridium ions are added.

[0056] Comparative Example 3

[0057] The difference from Example 1 is that no oxalic acid is added.

[0058] Comparative Example 4

[0059] The difference from Example 1 is that no polyhydroxy organic porous material is added.

[0060] After the preparation of Examples 1-3 and Comparative Examples 1-4, the anode plates were cut into square plates of 10 cm × 10 cm, and a metal titanium plate was used as a cathode, placed in an electrolytic cell, and the plate spacing was adjusted to 2 cm. 1 L of wastewater from a chemical enterprise (mainly containing halogenated aromatics and halogenated alkanes, with a COD of 966 mg / L) was taken for testing. During the test, the pH of the wastewater was adjusted to 7, the current was 4 A, and after electrolysis for 30 minutes, samples were taken and the COD value was tested using the national standard method. The results are shown in Table 1.

[0061] Table 1

[0062]

[0063] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Therefore, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing a porous electrocatalytic anode material, It is characterized in that The steps include: The porous electrocatalytic anode material is prepared by coating the coating liquid on the titanium metal substrate treated by immersion in inorganic acid by multiple coatings, and performing a programmed temperature rise treatment in an inert atmosphere after each coating. The coating liquid contains transition metal ions, polycarboxylic acids and polyhydroxy organic porous materials; The transition metal ions include first transition metal ions and second transition metal ions, the first transition metal ions include iron and cobalt ions, and the second transition metal ions include ruthenium and iridium ions; The polyhydroxy organic porous material is COF-BTA-DHBZ; The programmed temperature rise is to first rise to a first temperature to volatilize the solvent in the coating liquid, and then rise to a second temperature to carbonize the polyhydroxy organic porous material; the first temperature is 110-130°C, and the temperature is raised to the first temperature at a heating rate of 4-8°C per minute, and maintained for 1-3 hours; the second temperature is 800-1200°C, and the temperature is raised to the second temperature at a heating rate of 3-6°C per minute, and maintained for 3-6 hours.

2. The method for preparing the porous electrocatalytic anode material according to claim 1, It is characterized in that The inorganic acid includes one or more of hydrochloric acid, nitric acid, phosphoric acid or sulfuric acid. The inorganic acid soaking treatment time is 12-24 hours, and the treatment temperature is 50-80°C.

3. The method for preparing the porous electrocatalytic anode material according to claim 1, It is characterized in that The dosage of the first transition metal ion is 3-5 g / 1 m 2 Titanium metal matrix, the amount of ruthenium ions is 5-15 g / 1m 2 Titanium metal matrix, the dosage of iridium ions is 3-5 g / 1m 2 Titanium metal base.

4. The method for preparing the porous electrocatalytic anode material according to any one of claims 1 to 3, It is characterized in that The polycarboxylic acid includes one or more of citric acid, oxalic acid, succinic acid, adipic acid, azelaic acid or sebacic acid, and the amount of the polycarboxylic acid is 1.5-3 times the mass of the transition metal ion.

5. The method for preparing the porous electrocatalytic anode material according to any one of claims 1 to 3, It is characterized in that The amount of the polyhydroxy organic porous material is 1.5-3 times the mass of the transition metal ions.

6. The method for preparing the porous electrocatalytic anode material according to any one of claims 1 to 3, It is characterized in that The multiple coatings are applied 15-20 times.

7. A porous electrocatalytic anode material, It is characterized in that It is prepared by the method described in any one of claims 1 to 6.

8. Use of the porous electrocatalytic anode material according to claim 7 in the electrocatalytic oxidation of organic wastewater.

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