A pH-responsive intelligent oil-water separation copper mesh and a preparation method thereof

Abstract

The application belongs to the field of materials, and discloses a pH-responsive intelligent oil-water separation copper mesh and a preparation method thereof. The preparation method is as follows: the copper mesh is sequentially ultrasonically cleaned in ethanol and water and dried to remove oil stains and make the surface clean. The dried copper mesh is soaked in a silver nitrate solution for 1h-4h. After being taken out, the copper mesh is soaked in a dodecyl mercaptan and mercapto-undecanoic acid ethanol solution for 24h-48h, then the surface solution is washed clean with ethanol, and finally dried to obtain a pH-responsive intelligent oil-water separation copper mesh. The pH-responsive intelligent oil-water separation copper mesh can realize quick switching between hydrophilicity and hydrophobicity on the surface, selectively recover oil and water, and has strong reusability.

Description

Technical Field

[0001] This invention belongs to the field of materials and relates to a pH-responsive intelligent oil-water separation copper mesh and its preparation method. Background Technology

[0002] Traditional oil-water separation technologies and materials often possess only single wettability properties, such as being oleophilic and hydrophobic or oleophobic and hydrophilic, allowing for selective recovery of either oil or water. This limitation makes them unsuitable for applications in complex environments and restricts their application scope. Therefore, developing an oil-water separation material with intelligent interface response has broad application prospects. Summary of the Invention

[0003] This invention provides a pH-responsive intelligent oil-water separation copper mesh and its preparation method. The surface of the pH-responsive intelligent oil-water separation copper mesh can achieve rapid switching between hydrophilic and hydrophobic properties, selectively recover oil and water, and has extremely strong reusability.

[0004] This invention provides a method for preparing a pH-responsive intelligent oil-water separation copper mesh, comprising the following steps:

[0005] S1. Soak the cleaned copper mesh in silver nitrate solution for 1-4 hours, then remove and dry it;

[0006] S2. The copper mesh obtained in step S1 is soaked in an ethanol solution of dodecyl mercaptan and mercaptoundecanoic acid for 24h to 48h. After soaking, the surface solution is rinsed off with ethanol and dried to obtain a pH-responsive intelligent oil-water separation copper mesh.

[0007] Preferably, the aperture of the copper mesh is 100 micrometers.

[0008] Preferably, the cleaning process specifically involves ultrasonically cleaning the copper mesh sequentially in ethanol and water, and then drying it at 50°C.

[0009] Preferably, the concentration of the silver nitrate solution is 5-15 wt%.

[0010] Preferably, in the ethanol solution of dodecyl mercaptothiol and mercaptoundecanoic acid, the molar concentration of dodecyl mercaptothiol is 0.3-0.7 mmol / L, the molar concentration of undecanoic acid is 0.3-0.7 mmol / L, and the molar ratio of dodecyl mercaptothiol to mercaptoundecanoic acid is 1:1.

[0011] The present invention also provides a pH-responsive intelligent oil-water separation copper mesh prepared by the above-described preparation method.

[0012] Compared with the prior art, the present invention has the following technical effects:

[0013] (1) Silver nitrate reacts chemically with copper mesh at the interface to produce silver and copper nitrate. The copper nitrate dissolves in the solution, and elemental silver can uniformly cover the surface of the copper mesh without the need for intermediate chemical bonds. Furthermore, dodecyl mercaptothiol and mercaptoundecanoic acid form chelates with elemental silver through the mercapto groups. The preparation method does not require heating or complex reaction equipment, the process is simple, energy-saving and emission-reducing, green and environmentally friendly, and easier to industrialize.

[0014] (2) This intelligent oil-water separation copper mesh exhibits pH responsiveness because the carboxyl group in mercaptoundecyl acid undergoes protonation in acidic solutions, becoming hydrophilic. However, this hydrophilicity is insufficient to compete with the hydrophobicity of the alkyl group in dodecyl mercaptan at the same concentration, resulting in an overall hydrophobic-oleophilic property. In alkaline solutions, deprotonation occurs, forming carboxyl anions and exhibiting stronger hydrophilicity, masking the hydrophobicity of dodecyl mercaptan. This allows for the switchable wetting properties of hydrophobic-oleophilic and hydrophilic-oleophobic properties, enabling selective recovery of oil and water to meet practical application requirements. Detailed Implementation

[0015] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0016] Example 1

[0017] A 100-micron aperture copper mesh was ultrasonically cleaned and dried sequentially in ethanol and water to remove oil and ensure a clean surface. The dried copper mesh was then immersed in a 5% silver nitrate solution for 1 hour. After removal and drying, it was immersed in a 100 mL mixture of dodecyl mercaptothiol and mercaptoundecanoic acid in ethanol for 24 hours. The mass concentrations of both dodecyl mercaptothiol and mercaptoundecanoic acid in the mixture were 0.3 mmol / L. Subsequently, the surface solution was rinsed off with ethanol, and finally dried to obtain a pH-responsive intelligent oil-water separation copper mesh, sample 1. This copper mesh is hydrophobic and oleophilic in an aqueous solution at pH=7, allowing oil to pass through but water to pass through, thus separating and recovering heavy oil. In a sodium hydroxide solution at pH=14, it is hydrophilic and oleophobic, allowing water to pass through but oil to pass through, thus separating light oil and recovering water.

[0018] Example 2

[0019] A 100-micron aperture copper mesh was ultrasonically cleaned and dried sequentially in ethanol and water to remove oil and ensure a clean surface. The dried copper mesh was then immersed in a 5% silver nitrate solution for 2 hours. After removal and drying, it was immersed in a 100 mL mixture of dodecyl mercaptothiol and mercaptoundecanoic acid in ethanol for 24 hours. The mass concentrations of both dodecyl mercaptothiol and mercaptoundecanoic acid in the mixture were 0.3 mmol / L. Subsequently, the surface solution was rinsed off with ethanol, and finally dried to obtain a pH-responsive intelligent oil-water separation copper mesh, sample 2. This copper mesh is hydrophobic and oleophilic in an aqueous solution at pH=7, allowing oil to pass through but water to pass through, thus separating and recovering heavy oil. In a sodium hydroxide solution at pH=14, it is hydrophilic and oleophobic, allowing water to pass through but oil to pass through, thus separating light oil and recovering water.

[0020] Example 3

[0021] A 100-micron aperture copper mesh was ultrasonically cleaned and dried sequentially in ethanol and water to remove oil and ensure a clean surface. The dried copper mesh was then immersed in a 5% silver nitrate solution for 1 hour. After removal and drying, it was immersed in a 100 mL mixture of dodecyl mercaptothiol and mercaptoundecanoic acid in ethanol for 24 hours. The mass concentrations of both dodecyl mercaptothiol and mercaptoundecanoic acid in the mixture were 0.4 mmol / L. Subsequently, the surface solution was rinsed off with ethanol, and finally dried to obtain a pH-responsive intelligent oil-water separation copper mesh, sample 3. This copper mesh is hydrophobic and oleophilic in an aqueous solution at pH=7, allowing oil to pass through but water to pass through, thus separating and recovering heavy oil. In a sodium hydroxide solution at pH=14, it is hydrophilic and oleophobic, allowing water to pass through but oil to pass through, thus separating light oil and recovering water.

[0022] Example 4

[0023] A 100-micron aperture copper mesh was ultrasonically cleaned and dried sequentially in ethanol and water to remove oil and ensure a clean surface. The dried copper mesh was then immersed in a 5% silver nitrate solution for 1 hour. After removal and drying, it was immersed in a 100 mL mixture of dodecyl mercaptothiol and mercaptoundecanoic acid in ethanol for 48 hours. The mass concentrations of both dodecyl mercaptothiol and mercaptoundecanoic acid in the mixture were 0.3 mmol / L. Subsequently, the surface solution was rinsed off with ethanol, and finally dried to obtain a pH-responsive intelligent oil-water separation copper mesh, sample 4. This copper mesh is hydrophobic and oleophilic in an aqueous solution at pH=7, allowing oil to pass through but water to pass through, thus separating and recovering heavy oil. In a sodium hydroxide solution at pH=14, it is hydrophilic and oleophobic, allowing water to pass through but oil to pass through, thus separating light oil and recovering water.

[0024] Example 5

[0025] A 100-micron aperture copper mesh was ultrasonically cleaned and dried sequentially in ethanol and water to remove oil and ensure a clean surface. The dried copper mesh was then immersed in a 5% silver nitrate solution for 1 hour. After removal and drying, it was immersed in a 100 mL mixture of dodecyl mercaptothiol and mercaptoundecanoic acid in ethanol for 24 hours. The mass concentrations of both dodecyl mercaptothiol and mercaptoundecanoic acid in the mixture were 0.5 mmol / L. Subsequently, the surface solution was rinsed off with ethanol, and finally dried to obtain a pH-responsive intelligent oil-water separation copper mesh, sample 5. This copper mesh is hydrophobic and oleophilic in an aqueous solution at pH=7, allowing oil to pass through but water to pass through, thus separating and recovering heavy oil. In a sodium hydroxide solution at pH=14, it is hydrophilic and oleophobic, allowing water to pass through but oil to pass through, thus separating light oil and recovering water.

[0026] Example 6

[0027] A 100-micron aperture copper mesh was ultrasonically cleaned sequentially in ethanol and water, and then dried to remove oil and ensure a clean surface. The dried copper mesh was then immersed in a 5% silver nitrate solution for 1 hour. After removal and drying, it was immersed in a 100 mL ethanol mixture of dodecyl mercaptoside and mercaptoundecanoic acid for 24 hours. The mass concentrations of dodecyl mercaptoside and mercaptoundecanoic acid in the mixture were 0.1 mmol / L and 0.5 mmol / L, respectively. Subsequently, the surface solution was rinsed off with ethanol, and finally dried to obtain sample 6. This copper mesh is non-hydrophobic in an aqueous solution at pH 7, with a water contact angle of 88°. This is because the high content of mercaptoundecanoic acid exhibits hydrophilic properties, while the low content of dodecyl mercaptoside, although hydrophobic, is insufficient to compete and mask the hydrophilicity of the high-content mercaptoundecanoic acid, resulting in a relatively weakly hydrophilic interface (contact angle less than 90°). The enhanced hydrophilicity observed in a sodium hydroxide solution at pH 14 is due to the ionization of hydrogen ions from the carboxyl group of mercaptoundecanoic acid under alkaline conditions, resulting in stronger hydrophilicity compared to the unionized state. The hydrophobicity of dodecyl mercaptan, due to its low content, is largely masked by the relatively strong hydrophilicity, leading to a stronger overall hydrophilicity at the interface. Based on the above, this comparative example cannot demonstrate the actual effects of the present invention.

[0028] Example 7

[0029] A 100-micron aperture copper mesh was ultrasonically cleaned and dried sequentially in ethanol and water to remove oil and ensure a clean surface. The dried copper mesh was then immersed in a 5% silver nitrate solution for 1 hour. After removal and drying, it was immersed in a 100 mL mixture of dodecyl mercaptoside and mercaptoundecanoic acid in ethanol for 24 hours. The concentrations of dodecyl mercaptoside and mercaptoundecanoic acid in the mixture were 0.5 mmol / L and 0.2 mmol / L, respectively. The mesh was then rinsed with ethanol and dried to obtain sample 7. Mercaptoundecanoic acid is the pH-sensitive component in this invention and is hydrophilic. In this embodiment, the content of mercaptoundecanoic acid is relatively low compared to dodecyl mercaptoside, and its pH sensitivity and hydrophilicity are masked by the hydrophobicity of dodecyl mercaptoside. Sample 7 exhibits superhydrophobicity under neutral conditions. At pH = 14, due to the ionization of undecanoic acid, the hydrophilicity increases, and the hydrophobicity decreases somewhat, but it still exhibits hydrophobicity, making intelligent separation and oil recovery difficult.

[0030] The conventional method for testing water contact angle was used, which involves selecting five sites on a sample to measure the water contact angle and taking the average value. The test solutions were an aqueous solution with pH=7 and a sodium hydroxide solution with pH=14. The results are shown in the table below.

[0031] Table 1. Contact angles of samples from Examples 1-7 in aqueous solution at pH 7 and sodium hydroxide solution at pH 14.

[0032] sample Aqueous solution with pH = 7 (°) Sodium hydroxide solution with pH = 14 (°) 1 145 0 2 146 0 3 150 0 4 148 0 5 142 0 6 88 20 7 152 125

[0033] Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to this invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a pH-responsive intelligent oil-water separation copper mesh, characterized in that, Includes the following steps: S1. Soak the cleaned copper mesh in silver nitrate solution for 1-4 hours, then remove and dry it; S2. The copper mesh obtained in step S1 is soaked in an ethanol solution of dodecyl mercaptan and mercaptoundecanoic acid for 24h~48h, then removed and rinsed with ethanol to remove the surface solution, and dried to obtain a pH-responsive intelligent oil-water separation copper mesh.

2. The preparation method according to claim 1, characterized in that, The copper mesh has an aperture of 100 micrometers.

3. The preparation method according to claim 1, characterized in that, The cleaning process specifically involves ultrasonically cleaning the copper mesh in ethanol and water sequentially, followed by drying at 50°C.

4. The preparation method according to claim 1, characterized in that, The concentration of the silver nitrate solution is 5-15 wt%.

5. The preparation method according to claim 1, characterized in that, In the ethanol solution of dodecyl mercaptothiol and mercaptoundecanoic acid, the molar concentration of dodecyl mercaptothiol is 0.3~0.7 mmol / L, and the molar concentration of undecanoic acid is 0.3 mmol~0.7 mmol / L.

6. The preparation method according to claim 5, characterized in that, In the ethanol solution of dodecyl mercaptothiol and mercaptoundecanoic acid, the molar ratio of dodecyl mercaptothiol to mercaptoundecanoic acid is 1:

1.

7. The pH-responsive intelligent oil-water separation copper mesh prepared by the preparation method according to any one of claims 1-6.