A porous carbon@polyaniline composite material, a preparation method and application thereof, and a corn straw charcoal-based paint and coating

Abstract

The present application provides a kind of porous carbon polyaniline composite material and its preparation method and application, corn straw charcoal-based paint and coating, belong to biomass utilization technical field.The present application is based on corn straw raw material, and porous corn straw charcoal composite material of polyaniline supported, i.e.porous carbon polyaniline composite material.After water contact angle and electrochemical impedance test, it is found that porous carbon polyaniline composite coating has excellent water solution repellency and larger resistance, its superhydrophobicity makes it have excellent self-cleaning and stain resistance, and the pi-pi conjugation of polyaniline along polymer main chain makes it have high conductivity and redox activity, and it shows excellent performance in corrosion protection.

Description

Technical Field

[0001] This invention belongs to the field of biomass utilization technology, specifically relating to a porous carbon@polyaniline composite material and its preparation method and application, as well as corn stalk carbon-based coatings and coatings. Background Technology

[0002] Due to factors such as smog and construction dust, there are a significant amount of dust particles in the air, increasing the manpower and material costs of cleaning exposed surfaces such as high-rise building facades, glass, and automobiles. On the other hand, while metal products are widely used in daily life, the extensive use of metals and their alloys has also led to corrosion problems, hindering human development and scientific and technological progress.

[0003] Superhydrophobic surfaces possess excellent water and aqueous solutions repellent properties, enabling self-cleaning of solid surfaces and corrosion protection for metals, thus providing an effective solution to the aforementioned problems. Currently, the preparation of superhydrophobic materials often utilizes fluorinated compounds and toxic chemicals.

[0004] The aforementioned factors increase the production cost of superhydrophobic materials and also have a significant environmental impact, making them unsuitable for industrial production requirements. Therefore, it is imperative to develop new environmentally friendly, non-toxic, harmless, and biodegradable superhydrophobic materials. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a porous carbon@polyaniline composite material, its preparation method and application, and corn stalk carbon-based coatings and coatings. The porous carbon@polyaniline composite material provided by this invention is biodegradable, and the corn stalk carbon-based coating prepared from it exhibits biodegradability, superhydrophobicity, excellent stain resistance, and the ability to delay metal corrosion. This invention does not use fluorine-containing compounds or toxic substances, making it environmentally friendly.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] The present invention provides a porous carbon@polyaniline composite material, comprising porous carbon from corn stalks and polyaniline loaded on the surface of the porous carbon from corn stalks.

[0008] Preferably, the mass ratio of the polyaniline to the porous carbon from corn stalks is (3-5):4.

[0009] Preferably, the specific surface area of ​​the corn stalk porous charcoal is 229.7 m². 2 / g; porosity 0.402; average pore size 0.427nm; pore volume 0.0245cm³ 3 / g.

[0010] Preferably, the method for preparing the porous charcoal from corn stalks includes the following steps:

[0011] Corn stalk powder is mixed with an alkaline solution and subjected to alkali treatment to obtain alkali-treated corn stalk powder.

[0012] The alkali-treated corn stalk powder is mixed with a bicarbonate solution for pre-activation to obtain pre-activated corn stalk powder.

[0013] Under inert gas protection, the pre-activated corn stalk powder is calcined to obtain porous corn stalk carbon.

[0014] Preferably, the pre-activation temperature is 80°C and the time is 8–12 h; the calcination temperature is 400–750°C and the holding time is 1–3 h.

[0015] This invention provides a method for preparing the porous carbon@polyaniline composite material described above, comprising the following steps:

[0016] Porous carbon from corn stalks was mixed with a polyaniline solution to obtain a porous carbon@polyaniline composite material.

[0017] This invention provides the application of the porous carbon@polyaniline composite material described in the above-described scheme or the porous carbon@polyaniline composite material prepared by the preparation method described in the above-described scheme in corrosion protective coatings.

[0018] This invention provides a corn stalk carbon-based coating, comprising a porous carbon@polyaniline composite material, polydimethylsiloxane, a curing agent, and an organic solvent; the porous carbon@polyaniline composite material is the porous carbon@polyaniline composite material described in the above scheme or the porous carbon@polyaniline composite material prepared by the preparation method described in the above scheme.

[0019] Preferably, the mass ratio of the porous carbon@polyaniline composite material to polydimethylsiloxane is (5-15):(7-14);

[0020] The mass ratio of the porous carbon@polyaniline composite material to the volume ratio of the organic solvent is (0.05~0.15)g:(3~6)mL.

[0021] This invention provides a corn stalk carbon-based coating, which is obtained by coating a metal surface with the corn stalk carbon-based coating described in the above scheme and then drying it.

[0022] This invention provides a porous carbon@polyaniline composite material, comprising porous carbon from corn stalks and polyaniline loaded on the surface of the porous carbon from corn stalks. The porous carbon@polyaniline composite material provided by this invention is biodegradable. The corn stalk carbon-based coating (porous carbon@polyaniline composite coating) prepared from it exhibits excellent aqueous solution repellency and high electrical resistance. Its superhydrophobicity gives it excellent self-cleaning and stain resistance. Furthermore, the π-π conjugation of polyaniline along the polymer backbone endows it with high conductivity and redox activity, demonstrating excellent performance in corrosion protection. Moreover, the porous carbon@polyaniline composite material is free of fluorine and other toxic substances, making it environmentally friendly.

[0023] This invention provides a method for preparing a corn stalk carbon-based coating. Using corn stalks as raw material, polyaniline is loaded onto the surface of porous corn stalk carbon to prepare a porous carbon@polyaniline composite material; finally, a simple drop-coating method is used to prepare the corn stalk carbon-based coating. The preparation method provided by this invention does not use fluorine-containing compounds or toxic substances, making it green and environmentally friendly. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 XRD patterns of BC, PANI, and BC@PANI prepared in Example 1;

[0026] Figure 2 Raman spectra of BC, PANI, and BC@PANI prepared in Example 1;

[0027] Figure 3 Infrared spectra of BC, PANI, and BC@PANI prepared in Example 1;

[0028] Figure 4 XPS spectra of BC, PANI, and BC@PANI prepared in Example 1;

[0029] Figure 5 SEM images of BC, PANI, and BC@PANI prepared in Example 1;

[0030] Figure 6 SEM images of straw charcoal CP-600 prepared in Comparative Example 1, straw charcoal CP-400 prepared in Comparative Example 2, and straw charcoal CP-800 prepared in Comparative Example 3.

[0031] Figure 7 SEM image of the BC@PANI coating prepared in Example 1;

[0032] Figure 8 Static water contact angle diagrams of the BC@PANI coating prepared in Example 1, the BC coating prepared in Comparative Example 4, and the polyaniline coating prepared in Comparative Example 5;

[0033] Figure 9 Static water contact angle diagrams of the CP-600 coating prepared in Comparative Example 6, the CP-400 coating prepared in Comparative Example 7, and the CP-800 coating prepared in Comparative Example 8.

[0034] Figure 10 Nyquist plots of the BC@PANI coating prepared in Example 1, the BC coating prepared in Comparative Example 4, and the polyaniline coating prepared in Comparative Example 5 in 3.5% sodium chloride solution;

[0035] Figure 11 This is a test image of the self-cleaning performance of the porous carbon@polyaniline coating surface in Example 1. Detailed Implementation

[0036] The present invention provides a porous carbon@polyaniline composite material, comprising porous carbon from corn stalks and polyaniline loaded on the surface of the porous carbon from corn stalks.

[0037] Unless otherwise specified, all materials and equipment used in this invention are commercially available.

[0038] In this invention, the preferred mass ratio of polyaniline to the surface area of ​​porous corn stalk carbon is (3-5):4, more preferably (3.5-4.5):4. In this invention, the preferred specific surface area of ​​the porous corn stalk carbon is 229.7 m². 2 / g; porosity preferably 0.402; average pore size preferably 0.427nm; pore volume preferably 0.0245cm³. 3 / g.

[0039] The porous carbon@polyaniline composite material provided by this invention is biodegradable. The corn stalk carbon-based coating (porous carbon@polyaniline composite coating) prepared from it has excellent aqueous solution repellency and high electrical resistance. Its superhydrophobicity gives it excellent self-cleaning and stain resistance. Furthermore, the π-π conjugation of polyaniline along the polymer backbone gives it high conductivity and redox activity, exhibiting excellent performance in corrosion protection. Moreover, the porous carbon@polyaniline composite material is free of fluorine and other toxic substances, making it green and environmentally friendly.

[0040] In this invention, the method for preparing the porous charcoal from corn stalks preferably includes the following steps:

[0041] Corn stalk powder is mixed with an alkaline solution and subjected to alkali treatment to obtain alkali-treated corn stalk powder.

[0042] The alkali-treated corn stalk powder is mixed with a bicarbonate solution for pre-activation to obtain pre-activated corn stalk powder.

[0043] Under inert gas protection, the pre-activated corn stalk powder is calcined to obtain porous corn stalk carbon.

[0044] This invention involves mixing corn stalk powder with an alkaline solution and subjecting it to alkali treatment to obtain alkali-treated corn stalk powder.

[0045] In this invention, the corn stalk powder is preferably made from crushed corn stalks. This invention does not have a specific limitation on the source of the corn stalks; they can be obtained from sources well known in the art.

[0046] The present invention does not impose any particular limitation on the crushing process of the corn stalks; any process well-known in the art that yields corn stalk powder of 100-200 mesh is acceptable. In an embodiment of the present invention, the corn stalks are specifically cut into small pieces, and then washed, dried, ground, and sieved in sequence, with the undersize material collected.

[0047] In this invention, the alkaline solution preferably comprises an aqueous sodium hydroxide solution; the concentration of the alkaline solution is preferably 4-6 mol / L, more preferably 5 mol / L. In this invention, the mass ratio of the corn stalk powder to the volume ratio of the alkaline solution is preferably 1 g:(15-25) mL, more preferably 1 g:(18-22) mL.

[0048] In this invention, the alkali treatment temperature is preferably room temperature, and the alkali treatment time is preferably 1.5 to 2.5 hours, more preferably 2 hours. In this invention, the alkali treatment is preferably carried out under stirring conditions.

[0049] After the alkali treatment is completed, the present invention preferably washes, dries, and grinds the resulting material in sequence. The present invention does not impose any particular limitations on the washing, drying, and grinding processes; they can be performed according to processes well known in the art.

[0050] This invention uses alkali treatment to destroy the waxy layer on the surface of corn stalks, removing oils and waxes; at the same time, it weakens the binding between cellulose, hemicellulose and lignin in the corn stalks, thereby increasing the specific surface area of ​​the corn stalks and increasing the number of active sites.

[0051] After obtaining the alkali-treated corn stalk powder, the present invention mixes the alkali-treated corn stalk powder with a bicarbonate solution for pre-activation to obtain pre-activated corn stalk powder.

[0052] In this invention, the bicarbonate solution preferably comprises a sodium bicarbonate solution; the bicarbonate solution is preferably obtained by dissolving bicarbonate in water; and the concentration of the bicarbonate solution is preferably 60 g / L.

[0053] In this invention, the mass ratio of the alkali-treated corn stalk powder to bicarbonate is preferably 1:(0.95-1.05), and more preferably 1:1.

[0054] In this invention, the pre-activation temperature is preferably 80°C; the time is preferably 8 to 12 hours, and more preferably 10 to 11 hours.

[0055] After the pre-activation is completed, the present invention preferably grinds the obtained materials sequentially.

[0056] This invention utilizes the carbon dioxide produced during the high-temperature decomposition of sodium bicarbonate to create more pores during the carbonization of corn stalks, allowing for the loading of more polyaniline onto the surface.

[0057] After obtaining the preactivated corn stalk powder, the present invention calcines the preactivated corn stalk powder under inert gas protection to obtain porous corn stalk carbon.

[0058] In this invention, the inert gas preferably includes nitrogen. In this invention, the calcination temperature is preferably 400–750°C, more preferably 500–700°C, and even more preferably 600°C; the holding time for calcination is preferably 1–3 hours, more preferably 2 hours; the calcination is preferably performed by heating from room temperature to the calcination temperature; and the heating rate is preferably 5°C / min. In this invention, the calcination is preferably carried out in a tube furnace.

[0059] After the calcination is completed, the present invention preferably collects the carbonized corn stalk powder and washes and dries it in sequence.

[0060] In this invention, the washing process preferably uses a hydrochloric acid solution; the concentration of the hydrochloric acid solution is preferably 1 mol / L. This invention does not have particular requirements on the amount of hydrochloric acid solution used; any amount well-known in the art can be used. In this invention, the washing process is preferably carried out under stirring conditions.

[0061] This invention uses hydrochloric acid solution to wash the obtained carbonized corn stalk powder, which can remove excess sodium bicarbonate and sodium carbonate produced after calcination.

[0062] In this invention, the drying temperature is preferably 60°C. This invention does not impose any particular limitations on the stirring and drying process; it can be carried out according to processes well known in the art.

[0063] In the calcination process of this invention, the pre-activated corn stalk powder is thermally decomposed under anaerobic or extremely low oxygen content in a closed, high-temperature environment to obtain carbon particles with a rough layered structure, liquid bio-oil, and syngas containing hydrocarbons. At the same time, the carbon dioxide released by the high-temperature decomposition of sodium bicarbonate causes more pores to be generated during the carbonization of corn stalks, which can load more polyaniline on the surface.

[0064] This invention provides a method for preparing the porous carbon@polyaniline composite material described above, comprising the following steps:

[0065] Porous carbon from corn stalks was mixed with a polyaniline solution to obtain a porous carbon@polyaniline composite material.

[0066] In this invention, the preparation of the polyaniline solution preferably includes the following steps:

[0067] The first protic acid, the initiator, and the first solvent are mixed to obtain an initiator solution.

[0068] The second protic acid, aniline, and the second solvent are mixed a second time to obtain an aniline solution;

[0069] The initiator solution is added to the aniline solution to carry out a polymerization reaction, thereby obtaining a polyaniline solution.

[0070] In this invention, the first solvent and the second solvent are independently water; the first protic acid and the second protic acid are preferably citric acid. In this invention, the mass ratio of the first protic acid to the initiator is preferably (0.5–1.5):(0.13–0.15), more preferably 1:0.14. In this invention, the mass ratio of the initiator to the volume ratio of the first solvent is preferably (0.13–0.15) g:10 mL, more preferably 0.14 g:10 mL.

[0071] In this invention, the first mixing is preferably carried out under stirring conditions. The stirring process is not particularly demanding, as long as it is sufficient to dissolve the first protic acid and the initiator.

[0072] In this invention, the preferred mass ratio of the second protic acid to the volume ratio of aniline is (0.8–1.2) g : (0.03–0.05) mL, more preferably 1 g : 0.04 mL. In this invention, the preferred volume ratio of aniline to the second solvent is (0.03–0.05) : 10, more preferably 0.04 : 10.

[0073] In this invention, the second mixing is preferably carried out under stirring conditions. The stirring process is not particularly demanding, as long as it ensures that the second protic acid and aniline are mixed uniformly.

[0074] In this invention, the first and second protic acids serve two purposes: providing the acidity required for the reaction medium, and simultaneously entering the polyaniline skeleton as dopants to impart a certain degree of conductivity.

[0075] In this invention, the volume ratio of aniline to initiator is preferably (0.03-0.05) mL:(0.13-0.15) g, and more preferably 0.04 mL:0.14 g.

[0076] In this invention, the polymerization reaction is preferably carried out at room temperature and for a duration of 8 hours.

[0077] In this invention, the initiator solution is preferably added dropwise to the aniline solution. During the polymerization reaction, excessively high temperatures can lead to a decrease in the molecular weight and electrical conductivity of the synthesized polyaniline. Furthermore, the reaction between ammonium persulfate and aniline generates a large amount of gas (O2) and is exothermic. Therefore, by controlling the rate of addition of the initiator solution (solution a) to the aniline solution (solution b), the polymerization temperature can be controlled, which helps to improve the performance of polyaniline and the safety of the experiment.

[0078] After the polymerization reaction is completed, the present invention preferably mixes the porous carbon from corn stalks with a polyaniline solution to obtain a porous carbon@polyaniline composite material.

[0079] In this invention, the preferred mass ratio of the porous corn stalk charcoal to polyaniline is 1:(0.8-1.2).

[0080] In this invention, the preferred temperature for mixing the porous corn stalk charcoal with the polyaniline solution is room temperature, and the preferred time is 8 hours.

[0081] The present invention mixes the porous charcoal made from corn stalks with a polyaniline solution, thereby enabling the polyaniline to be uniformly loaded onto the surface of the porous charcoal made from corn stalks.

[0082] After mixing the porous corn stalk charcoal with the polyaniline solution, the present invention preferably washes, dries, and grinds the resulting material. In this invention, the washing preferably uses pure water and anhydrous ethanol. The present invention does not have particular limitations on the drying temperature and time; temperatures and times well known in the art can be used. After grinding, the material is preferably sieved using a 100-mesh screen.

[0083] This invention provides the application of the porous carbon@polyaniline composite material described above in corrosion protective coatings.

[0084] This invention provides a corn stalk carbon-based coating, comprising a porous carbon@polyaniline composite material, polydimethylsiloxane, a curing agent, and an organic solvent; the porous carbon@polyaniline composite material is the porous carbon@polyaniline composite material described in the above scheme or the porous carbon@polyaniline composite material prepared by the preparation method described in the above scheme.

[0085] In this invention, the preferred method for preparing the corn stalk carbon-based coating includes the following steps: mixing the porous carbon@polyaniline composite material, polydimethylsiloxane, a curing agent, and an organic solvent to obtain the corn stalk carbon-based coating. In a specific embodiment of this invention, it is preferable to mix the porous carbon@polyaniline composite material, polydimethylsiloxane, and an organic solvent, subject the mixture to a first ultrasonic treatment, then add the curing agent, and finally subject it to a second ultrasonic treatment to obtain the corn stalk carbon-based coating.

[0086] In this invention, the curing agent preferably comprises a polydimethylsiloxane curing agent. In this invention, the polydimethylsiloxane and the polydimethylsiloxane curing agent are a two-component kit product consisting of liquid components A and B. In this invention, the mass ratio of the polydimethylsiloxane and the polydimethylsiloxane curing agent is preferably 10:1.

[0087] In this invention, the duration of the first ultrasound is preferably 30 minutes; the duration of the second ultrasound is preferably 15 minutes. This invention does not have any particular requirements for the power of the ultrasound; any power known in the art can be used.

[0088] In this invention, the organic solvent preferably includes toluene.

[0089] In this invention, the preferred mass ratio of the porous carbon@polyaniline composite material to polydimethylsiloxane is (5-15):(7-14), more preferably 1:1; the preferred mass ratio of the porous carbon@polyaniline composite material to the volume ratio of the solvent is (0.05-0.15)g:(3-6)mL, more preferably 0.1g:5mL.

[0090] This invention provides a corn stalk carbon-based coating, which is obtained by coating a metal surface with the corn stalk carbon-based coating described in the above scheme and then drying it.

[0091] In this invention, the corn stalk carbon-based coating is preferably applied to the metal surface by a drop-coating method and then dried to obtain a corn stalk carbon-based coating, denoted as porous carbon@polyaniline coating.

[0092] In this invention, the metal preferably includes iron and / or aluminum. In this invention, the drying temperature is preferably 20–80°C, more preferably 30–50°C.

[0093] In this invention, after testing the water contact angle and electrochemical AC impedance, it was found that the porous carbon@polyaniline composite coating has excellent aqueous solution repellency and high resistance. Its superhydrophobicity gives it excellent self-cleaning and stain resistance, and the π-π conjugation of polyaniline along the polymer backbone gives it high conductivity and redox activity, exhibiting excellent performance in corrosion protection.

[0094] To further illustrate the present invention, the following detailed description, in conjunction with the accompanying drawings and embodiments, describes a porous carbon@polyaniline composite material, its preparation method and application, as well as corn stalk carbon-based coatings and coatings, but these descriptions should not be construed as limiting the scope of protection of the present invention.

[0095] Example 1

[0096] Cut the corn stalks into small sections, wash them, and place them in a forced-air drying oven to dry at 80℃ for 12 hours. After drying, grind them into powder in a high-speed grinder, and sieve them using a 100-mesh screen to collect powder with uniform particle size.

[0097] Weigh 10g of the corn stalk powder and add it to 200mL of 5mol / L sodium hydroxide solution for alkali treatment. Stir magnetically for 2 hours. After stirring, add 300mL of distilled water, mix, and filter. Place the filter cake in 150mL of distilled water, adjust the pH to 5-6, filter, wash the filter cake until neutral, dry at 80℃ for 12 hours, and grind to obtain alkali-treated corn stalk powder.

[0098] Weigh 6g of the alkalized corn stalk powder and add it to 100mL of distilled water containing 6g of sodium bicarbonate solid. Dry the powder thoroughly in a forced-air drying oven at 80℃ and then grind it. Under nitrogen protection, place the ground powder in a quartz boat and calcine it in a tube furnace at 600℃. The heating rate of the tube furnace is 5℃ / min, and the holding time is 2h. After the tube furnace cools naturally to room temperature, collect the black powder and add 200mL of 1mol / L hydrochloric acid aqueous solution. Stir overnight and then filter and dry to obtain porous corn stalk charcoal (BC), denoted as material A.

[0099] Preparation of solution a and solution b: Dissolve 5g of citric acid in 50mL of distilled water. After dissolution, add 0.7g of ammonium persulfate and stir to dissolve, obtaining an initiator solution, denoted as solution a; Dissolve 5g of citric acid in 50mL of distilled water. After complete dissolution, add 0.2mL of aniline and continue stirring to obtain an aniline solution, denoted as solution b;

[0100] Under stirring conditions, solution a was added dropwise to solution b. After the addition was complete, 200 mg of material A was added to the mixed solution. The mixture was stirred and reacted continuously at room temperature for 8 hours. After the mixed solution had fully reacted, it was filtered. The filter cake was washed with pure water and anhydrous ethanol until the filtrate was colorless. After drying and grinding, porous carbon@polyaniline composite material (BC@PANI) was obtained, which was denoted as material C.

[0101] Add 0.1g of polydimethylsiloxane and 0.1g of component C to 5mL of toluene. After sonicating the mixture for 30min, add 0.01g of polydimethylsiloxane curing agent and continue sonicating for 15min to obtain the coating, i.e., the coating solution.

[0102] The coating solution was applied to the surface of an iron sheet using a drop-coating method to obtain a porous carbon@polyaniline coating.

[0103] Comparative Example 1

[0104] The preparation process of material A in Example 1 was repeated, except that sodium bicarbonate was not added: under nitrogen protection, the alkali-treated corn stalk powder was placed in a quartz boat and calcined in a tube furnace at 600°C to obtain corn stalk porous carbon CP-600.

[0105] Comparative Example 2

[0106] The preparation process of material A in Example 1 was repeated, except that sodium bicarbonate was not added. The alkalized corn stalk powder was placed in a quartz boat and calcined in a tube furnace at 400°C to obtain corn stalk porous carbon CP-400.

[0107] Comparative Example 3

[0108] The preparation process of material A in Example 1 was repeated, except that sodium bicarbonate was not added. The alkalized corn stalk powder was placed in a quartz boat and calcined in a tube furnace at 800°C to obtain corn stalk porous carbon CP-800.

[0109] Comparative Example 4

[0110] The preparation process of the coating solution in Example 1 was repeated, except that: 0.1g of polydimethylsiloxane and 0.1g of component A were added to 5mL of toluene, the mixed solution was sonicated for 30min, and then 0.01g of polydimethylsiloxane curing agent was added, and sonication was continued for 15min to obtain the coating solution.

[0111] A coating solution was applied to the surface of an iron sheet using a drop-coating method to obtain a porous carbon BC coating made from corn stalks.

[0112] Comparative Example 5

[0113] The preparation process of the coating solution in Example 1 was repeated, except that: 0.1g of polydimethylsiloxane and 0.1g of component B were added to 5mL of toluene, the mixed solution was sonicated for 30min, and then 0.01g of polydimethylsiloxane curing agent was added. The mixture was sonicated for another 15min to obtain the coating solution.

[0114] A coating solution was applied to the surface of an iron sheet using a drop-coating method to obtain a polyaniline (PANI) coating.

[0115] The preparation steps of material B are as follows:

[0116] Under stirring conditions, solution a was added dropwise to solution b (the preparation steps of solution a and solution b were the same as in Example 1), and the mixture was stirred continuously at room temperature for 8 hours. After the mixed solution had fully reacted, it was filtered. The filter cake was washed with pure water and anhydrous ethanol until the filtrate was colorless. After drying and grinding, polyaniline (PANI) was obtained, which was designated as material B.

[0117] Comparative Example 6

[0118] The preparation process of the coating solution in Example 1 was repeated, except that 0.05g of polydimethylsiloxane and 0.1g of corn stalk carbon porous carbon CP-600 were added to 7mL of anhydrous ethanol. After the mixed solution was sonicated for 30min, 0.005g of polydimethylsiloxane curing agent was added, and sonication was continued for 15min to obtain the coating solution.

[0119] The coating solution was applied to the surface of a glass slide using a drop-coating method to obtain a corn stalk porous carbon CP-600 coating.

[0120] Comparative Example 7

[0121] The preparation process of the coating solution in Example 1 was repeated, except that 0.05g of polydimethylsiloxane and 0.1g of corn stalk carbon porous carbon CP-400 were added to 7mL of anhydrous ethanol. After the mixed solution was sonicated for 30min, 0.005g of polydimethylsiloxane curing agent was added, and sonication was continued for 15min to obtain the coating solution.

[0122] The coating solution was applied to the surface of a glass slide using a drop-coating method to obtain a corn stalk porous carbon CP-400 coating.

[0123] Comparative Example 8

[0124] The coating preparation process in Example 1 was repeated, except that 0.05g of polydimethylsiloxane and 0.1g of corn stalk carbon porous carbon CP-800 were added to 7mL of anhydrous ethanol. After the mixed solution was sonicated for 30min, 0.005g of polydimethylsiloxane curing agent was added, and sonication was continued for 15min to obtain the coating solution.

[0125] The coating solution was applied to the surface of a glass slide using a drop-coating method to obtain a corn stalk porous carbon CP-800 coating.

[0126] Performance testing and structural characterization

[0127] (1) XRD tests were performed on the three materials prepared in Example 1. Figure 1 XRD patterns of porous charcoal (BC) from corn stalks, polyaniline (PANI), and porous char@polyaniline (BC@PANI) are shown. Figure 1 As can be seen, the XRD pattern of porous carbon from corn stalks shows two broad diffraction peaks at 2θ = 24.3° and 2θ = 42.3°, corresponding to the (002) and (100) crystal planes of graphitized carbon, respectively. The broad peaks indicate that the porous carbon from corn stalks is mainly composed of amorphous carbon, which also proves that the cellulose structure of corn stalks is destroyed at high temperatures, and the cellulose component is completely transformed into amorphous carbon. The XRD pattern of polyaniline shows that polyaniline has a partially crystalline structure, with two diffraction peaks observed near 2θ = 20.5° and 2θ = 25.3° corresponding to the (020) and (200) imine crystal planes, respectively. The characteristic peaks at 2θ = 24.3° and 2θ = 42.3° in the XRD pattern of porous carbon@polyaniline confirm the presence of carbon peaks. Meanwhile, weak peaks appeared at 2θ = 20.5° and 2θ = 25.3° in the porous carbon@polyaniline composite material, indicating that both corn stalk porous carbon and polyaniline coexist in the composite material. These XRD data demonstrate the successful preparation of the porous carbon@polyaniline composite material.

[0128] (2) To further demonstrate the successful preparation of polyaniline material on the surface of porous charcoal made from corn stalks, Raman spectroscopy was performed on samples of porous charcoal made from corn stalks, polyaniline, and porous char@polyaniline. The test results are as follows: Figure 2 As shown, two distinct absorption peaks can be observed in the spectrum of porous carbon from corn stalks, located at 1332 cm⁻¹. -1 and 1598cm -1 At wavelength. At 1332cm -1 The absorption peak at that point is due to sp 3 The D peak is caused by the presence of hybrid carbon atoms; it is located at 1598 cm⁻¹. -1 The absorption peak at that point is due to sp 2 The G peak is caused by vibrations of hybrid or graphitized carbon. In the spectrum of polyaniline, it appears at 616 cm⁻¹. -1 and 865cm -1 The characteristic absorption peaks appearing nearby are caused by benzene ring deformation and out-of-plane vibrations of aromatic rings, respectively; at 1335 cm⁻¹ -1 1394cm -1 and 1451cm -1The absorption peaks observed are characteristic peaks of polyaniline at different positions, belonging to in-plane CH4 and CH5, respectively. + Stretching vibrations, C=N stretching vibrations in the quinone ring, located at 1566 cm⁻¹ -1 The absorption peaks at the specified locations correspond to the stretching vibrations of the C and C rings in the benzene or quinone rings. After aniline was polymerized using corn stalk porous carbon as a template, the peaks of the composite material did not change significantly, indicating that the polyaniline in the porous carbon@polyaniline composite has the same structure as pure polyaniline. This proves that polyaniline can grow on the surface of corn stalk porous carbon through in-situ oxidative polymerization. This is consistent with the XRD analysis results.

[0129] (3) Fourier transform infrared spectroscopy was used to test the corn stalk porous char, polyaniline, and porous char@polyaniline prepared in Example 1. The results are as follows: Figure 3 As shown in the figure. It can be seen from the figure that the spectrum of PANI is at 1579 cm⁻¹. -1 1490cm -1 1309cm -1 1137cm -1 and 821cm -1 Absorption peaks appear on both sides. (1579 cm⁻¹) -1 and 1490cm -1 The nearby absorption peaks are attributed to the C=C stretching vibrations in the quinone and benzene rings, respectively; located at 1309 cm⁻¹. -1 The nearby absorption peak is attributed to the stretching vibration of CN in the aromatic amine; 1137 cm⁻¹ -1 The absorption peak at 821 cm⁻¹ is a characteristic peak of the stretching vibration of the quinone ring. -1 The absorption peak at 3455 cm⁻¹ belongs to the out-of-plane bending vibration of the aromatic CH bond. Meanwhile, it is clearly observed from the figure that the absorption peak of porous carbon@polyaniline in the low-frequency region is highly similar to that of polyaniline, indicating that polyaniline has been successfully polymerized on the surface of corn stalk porous carbon. The absorption peaks of corn stalk porous carbon, polyaniline, and porous carbon@polyaniline all show a peak at 3455 cm⁻¹. -1 A broad absorption band appears at this point, which can be attributed to -OH. Compared with porous carbon made from corn stalks, the absorption peak intensity of polyaniline and porous carbon@polyaniline is weakened at this point.

[0130] (4) XPS spectroscopy analysis can reveal the chemical composition and content changes of the prepared samples. The XPS spectra of the corn stalk porous char, polyaniline, and porous char@polyaniline prepared in Example 1 are shown below. Figure 4As shown, the characteristic XPS peaks of porous char from corn stalks appear near electron binding energies of 284 eV and 532 eV, confirming the presence of carbon and oxygen, with atomic percentages of 88.86% and 7.37%, respectively. Compared to porous char from corn stalks, the spectrum of polyaniline not only shows peaks at 284 eV and 532 eV, but also a new characteristic peak at 399 eV, which is attributed to nitrogen. The atomic percentages of carbon, oxygen, and nitrogen are 75%, 10.72%, and 10.2%, respectively. The presence of carbon, oxygen, and nitrogen was also detected in porous char@polyaniline, with atomic percentages of 77.59%, 7.25%, and 7.93%, respectively. The oxygen content in porous char@polyaniline was observed to be lower than that in polyaniline, which may be due to the presence of electron-rich substances such as aniline and polyaniline, leading to the reduction reaction of oxygen-containing functional groups.

[0131] (5) Figure 5 These are microscopic morphology images of the corn stalk porous char (a), polyaniline (b), and porous char@polyaniline (c) prepared in Example 1. The corn stalk porous char exhibits a typical loose porous structure with smooth and thin pore walls. Polyaniline has a fluffy structure, exhibiting a short rod-like network structure of varying lengths. After aniline oxidative polymerization and loading polyaniline onto the surface of the corn stalk porous char, a porous, fluffy structure can be observed, with polyaniline deposits randomly covering the surface of the corn stalk porous char, and some exhibiting agglomeration. The corn stalk porous char obtained by co-pyrolysis of straw and sodium bicarbonate has a distinct pore structure. Compared with the char obtained without sodium bicarbonate pyrolysis, the porous structure is increased, the specific surface area is larger, and more polyaniline can be loaded onto the surface. The specific pore parameters of the corn stalk porous char prepared in Example 1 are shown in Table 1.

[0132] (6) Figure 6 The images show the microstructures of straw charcoal CP-400(a), CP-600(b), and CP-800(c) prepared in Comparative Example 2 and Comparative Example 1, respectively. The microstructure of the straw charcoal is a rod-like structure with numerous protrusions on the surface. After carbonization, the specific surface area increases, and the roughness also increases. The specific surface area of ​​straw charcoal CP-400 is 5.38 m². 2 / g, the specific surface area of ​​straw charcoal CP-600 is 7.57m². 2 / g, the specific surface area of ​​straw charcoal CP-800 is 654.78m². 2 / g. With increasing pyrolysis temperature, the number of rod-like structures significantly increased. Compared to the straw char obtained at 400℃, the CP-600 obtained at 600℃ had more and more obvious dot-like protrusions on its surface, resulting in a larger specific surface area. The structure of CP-800 obtained at 800℃ was destroyed due to the high temperature. The pore parameters of corn straw carbonization at different pyrolysis (calcination) temperatures in Comparative Examples 1–3 and the porous corn straw char of Example 1 are shown in Table 1.

[0133] Table 1. Pore parameters of corn stalk carbonization at different pyrolysis temperatures in Comparative Examples 1-3 and the porous carbon from corn stalks in Example 1.

[0134] serial number Pyrolysis temperature (°C) Specific surface area (m² / g) Average pore size (nm) Porosity <![CDATA[Pore volume (cm 3 / g)]]> Comparative Example 2 400 5.38 7.55 0.055 0.0102 Comparative Example 1 600 7.57 6.88 0.065 0.0130 Comparative Example 3 800 654.78 1.83 1.78 0.308 Example 1 600 229.7 0.427 0.402 0.0245

[0135] (7) Figure 7 This is a microscopic morphology image of the porous carbon@polyaniline coating surface prepared in Example 1. After coating and drying, the porous carbon@polyaniline is uniformly distributed on the iron sheet surface. In high-magnification SEM, it can be observed that the coating surface has a rough structure with a large number of micro and nano protrusions. At the same time, it can be observed that these structures are closely arranged, which may be due to the bonding effect of polydimethylsiloxane.

[0136] (8) The wetting properties of the corn stalk porous carbon coating prepared in Comparative Example 4, the polyaniline coating prepared in Comparative Example 5, and the porous carbon@polyaniline coating prepared in Example 1 were tested respectively. The test results are as follows: Figure 8 As shown in the figures, a) is the porous carbon@polyaniline composite material prepared in Example 1, with a static water contact angle of 134±0.5°, exhibiting good hydrophobic properties. b) is the coating prepared from porous corn stalk carbon prepared in Comparative Example 4. The static water contact angle of the corn stalk porous carbon coating is 147±0.6°, close to 150°, demonstrating excellent hydrophobic properties. This is because the oxygen-containing functional groups such as hydroxyl groups on the surface of the straw fiber gradually decrease during the high-temperature pyrolysis process through deoxygenation, aromatization, and intramolecular condensation. c) is the coating prepared from polyaniline prepared in Comparative Example 5. The static water contact angle of the polyaniline coating is 141.5±1.3°, exhibiting good hydrophobicity. This is because citric acid-doped polyaniline itself has a certain degree of hydrophobicity. d represents the coating prepared by porous carbon@polyaniline in Example 1. The static water contact angle of the porous carbon@polyaniline coating is 154±0.5°, exhibiting superhydrophobic characteristics. This is due to the combined effect of the low surface energy of polydimethylsiloxane and the micro-rough structure of porous carbon@polyaniline.

[0137] (9) Wetting properties were tested on the corn stalk charcoal CP-600 (a) prepared in Comparative Example 1, the corn stalk charcoal coating CP-400 (b) prepared in Comparative Example 7, the corn stalk charcoal coating CP-600 (c) prepared in Comparative Example 6, and the corn stalk charcoal coating CP-800 (d) prepared in Comparative Example 8. The test results are as follows: Figure 9As shown in the figure, the results indicate that the hydrophobicity of the coatings first increases and then decreases with increasing carbonization temperature. The water contact angles of the corn stalk charcoal CP-600, CP-400, CP-600, and CP-800 coatings are 132.6±0.6°, 147±1°, 151±0.7°, and 146±0.6°, respectively, all exhibiting good hydrophobicity. However, the corn stalk charcoal CP-600 coating has the largest contact angle value and exhibits excellent superhydrophobicity.

[0138] (10) Figure 10 The Nyquist plots show the results for the porous carbon coating made from corn stalks (Comparative Example 4), the polyaniline coating made from polyaniline (Comparative Example 5), and the porous carbon@polyaniline coating made from polyaniline (Example 1). The plots show that all three coatings exhibit circular arcs in the high-frequency region, indicating varying degrees of corrosion protection. The porous carbon coating from corn stalks has the smallest arc radius and the fastest corrosion rate, while the porous carbon@polyaniline coating has the largest arc radius and the lowest corrosion rate. This suggests that depositing polyaniline on the surface of the porous carbon from corn stalks via in-situ polymerization improves the coating's corrosion resistance. It acts as a physical barrier, reducing the contact between the corrosive medium and the metal substrate. This is likely because the loading of polyaniline significantly increases the barrier capacity of the coating, thereby reducing the content of corrosive media at the coating-metal interface.

[0139] (11) Figure 11 This is a test image of the self-cleaning performance of the porous carbon@polyaniline coating prepared in Example 1. After the porous carbon@polyaniline coating was immersed in sludge water and then removed, no contaminants were observed on the coating surface, which was no different from before immersion. This is because the coating surface has low adhesion to contaminants and water, and the coating has excellent stain resistance.

[0140] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A corn stalk carbon-based coating, comprising a porous carbon@polyaniline composite material, polydimethylsiloxane, a curing agent, and an organic solvent; The porous carbon@polyaniline composite material comprises porous carbon from corn stalks and polyaniline loaded on the surface of the porous carbon from corn stalks.

2. The corn stalk carbon-based coating according to claim 1, characterized in that, The mass ratio of polyaniline to porous carbon from corn stalks is (3~5):

4.

3. The corn stalk carbon-based coating according to claim 2, characterized in that, The specific surface area of ​​the porous carbon from the corn stalks is 229.7 m². 2 / g; porosity 0.402; average pore size 0.427nm; pore volume 0.0245cm³ 3 / g.

4. The corn stalk carbon-based coating according to claim 3, characterized in that, The method for preparing porous carbon from corn stalks includes the following steps: Corn stalk powder is mixed with an alkaline solution and subjected to alkali treatment to obtain alkali-treated corn stalk powder. The alkali-treated corn stalk powder is mixed with a bicarbonate solution for pre-activation to obtain pre-activated corn stalk powder. Under inert gas protection, the pre-activated corn stalk powder is calcined to obtain porous corn stalk carbon.

5. The corn stalk carbon-based coating according to claim 4, characterized in that, The pre-activation temperature is 80℃ and the time is 8~12h; the calcination temperature is 400~750℃ and the holding time is 1~3h.

6. The corn stalk carbon-based coating according to any one of claims 1 to 5, characterized in that, The preparation method of the porous carbon@polyaniline composite material includes the following steps: Porous carbon from corn stalks was mixed with a polyaniline solution to obtain a porous carbon@polyaniline composite material.

7. The corn stalk carbon-based coating according to claim 1, characterized in that, The mass ratio of the porous carbon@polyaniline composite material to polydimethylsiloxane is (5~15):(7~14); The mass ratio of the porous carbon@polyaniline composite material to the volume ratio of the organic solvent is (0.05~0.15) g : (3~6) mL.

8. A corn stalk carbon-based coating, obtained by coating a metal surface with the corn stalk carbon-based coating as described in any one of claims 1 to 7 and then drying it.

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