A renewable oil-water separation material and its preparation method and application

Abstract

The present invention relates to the field of oil-water separation technology, and more specifically to a renewable oil-water separation material, its preparation method, and its application. In the present invention, a melamine foam material is immersed in a mixed solution consisting of sucrose, dopamine, and tris-hydroxymethylaminomethane-hydrochloric acid buffer solution to obtain a renewable oil-water separation material; the renewable oil-water separation material can quickly and efficiently separate different types of oily wastewater, such as cooking oil, industrial oil, and organic solvents, with a separation efficiency of over 99% and a separation flux of 10 4 ‑10 5 liters per square meter per hour. Furthermore, after being fully soaked in an ethanol solution, the used renewable oil-water separation material can be reused without significantly reducing the separation flux and efficiency. Furthermore, the renewable oil-water separation material exhibits a wide range of oil-water separation effects and is suitable for industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of oil-water separation, and in particular to a renewable oil-water separation material, a preparation method and an application thereof. Background Art

[0002] Membrane separation is widely used in oil-water separation technology due to its simplicity, high efficiency, and low energy consumption. Superhydrophilic membrane materials, in particular, exhibit excellent anti-fouling and self-cleaning capabilities due to their ability to quickly permeate water molecules and form a hydration layer, reducing adsorption of oils and organic solvents.

[0003] However, existing superhydrophilic membrane materials still face many challenges in achieving long-term, efficient oil-water separation. For example, after repeated oil-water separations, their surfaces are easily covered with oil, resulting in an irreversible decrease in flux and a gradual loss of separation function. Summary of the Invention

[0004] In order to better perform oil-water separation, the present invention provides a renewable oil-water separation material and a preparation method and application thereof.

[0005] A first aspect of the present invention provides a method for preparing a renewable oil-water separation material, comprising the following steps:

[0006] mixing sucrose, dopamine, and tris-hydrochloric acid buffer solution (Tris-HCl buffer solution) to obtain a mixed solution;

[0007] The melamine foam material is soaked in the mixed solution to obtain a renewable oil-water separation material.

[0008] The melamine foam material serves as the support material, which self-assembles in a tris-hydrochloric acid buffer solution containing sucrose and dopamine, thereby forming a renewable oil-water separation material with a surface coated with polydopamine. This renewable oil-water separation material can be reused for oil-water separation.

[0009] In one embodiment, the mass concentration of sucrose in the mixed solution is 0.15%-1%.

[0010] In one embodiment, the mass concentration of dopamine in the mixed solution is 1%-5%.

[0011] In one embodiment, the concentration of the Tris-HCl buffer solution is 0.1-0.2M.

[0012] In one embodiment, when the concentration of the Tris-hydrochloric acid buffer solution is 0.1 M, the concentration of sucrose in the mixed solution is 0.0015-0.01 g / mL, and the concentration of dopamine in the mixed solution is 0.01-0.05 g / mL. Preferably, when the concentration of the Tris-hydrochloric acid buffer solution is 0.1 M, the concentration of sucrose in the mixed solution is 0.0015 g / mL, and the concentration of dopamine in the mixed solution is 0.01 g / mL.

[0013] In one embodiment, the pH of the Tris-hydrochloric acid buffer solution is 7 to 10. Preferably, the pH of the Tris-hydrochloric acid buffer solution is 8.

[0014] In one embodiment, the temperature of the mixed solution is 30-60° C. and the soaking time is 4-24 hours when the melamine foam material is soaked in the mixed solution. Preferably, the temperature of the mixed solution is 45° C. and the soaking time is 12 hours when the melamine foam material is soaked in the mixed solution.

[0015] In one embodiment, before immersing the melamine foam material in the mixed solution, the method further comprises washing the melamine foam material with an ethanol solution.

[0016] A second aspect of the present invention provides a renewable oil-water separation material, which is obtained by the above-mentioned method for preparing a renewable oil-water separation material.

[0017] The third aspect of the present invention provides use of the renewable oil-water separation material in oil-water separation.

[0018] A fourth aspect of the present invention provides an oil-water separation method comprising the following steps:

[0019] placing the oil-water mixture on one side of the renewable oil-water separation material;

[0020] The water in the oil-water mixture is made to pass through the above-mentioned renewable oil-water separation material under the action of a driving force.

[0021] In one embodiment, the oil in the oil-water mixture is one or more of n-hexane, benzoic acid, petroleum ether, crude petroleum oil, refrigeration oil, paraffin oil, corn oil, soybean oil, and olive oil.

[0022] In the present invention, a melamine foam material is immersed in a mixed solution consisting of sucrose, dopamine, and tris(hydroxymethylaminomethane)-hydrochloric acid buffer solution to obtain a renewable oil-water separation material; the renewable oil-water separation material can quickly and efficiently separate different types of oily wastewater such as cooking oil, industrial oil, and organic solvents, with a separation efficiency of more than 99% and a separation flux of up to 10 4 -10 5liters per square meter per hour. Furthermore, after being fully soaked in an ethanol solution, the used renewable oil-water separation material can be reused without significantly reducing the separation flux and efficiency. Furthermore, the renewable oil-water separation material exhibits a wide range of oil-water separation effects and is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a surface scanning electron microscope photograph of the melamine foam material after impurities are removed in Comparative Example 1.

[0024] Figure 2 This is a surface scanning electron microscope photograph of the polydopamine-coated melamine material of Comparative Example 2.

[0025] Figure 3 This is a surface scanning electron microscope photograph of the renewable oil-water separation material according to Example 1 of the present invention.

[0026] Figure 4 The following are underwater oil contact angle photos and contact angle data diagrams of the materials in comparative example 2 and embodiment 1 of the present invention.

[0027] Figure 5 This is a photograph of the renewable oil-water separation material in Example 1 of the present invention in contact with water droplets.

[0028] Figure 6 This is a photograph of the renewable oil-water separation material of Example 1 of the present invention in contact with oil droplets underwater.

[0029] Figure 7 This is a graph showing contact angle data for renewable oil-water separation materials according to Examples 1 to 5 of the present invention.

[0030] Figure 8 This is a contact angle data diagram of the renewable oil-water separation material of Examples 1, 6 and 8 of the present invention.

[0031] Figure 9 This is a contact angle data diagram of the renewable oil-water separation material of Examples 1, 9 and 11 of the present invention.

[0032] Figure 10 This is a graph showing the contact angle data of the renewable oil-water separation materials of Examples 1, 12, and 13 of the present invention.

[0033] Figure 11 This is a photo of the oil-water separator used in the embodiment of the present invention.

[0034] Figure 12 This is a photo of the oil-water separation process of Example 14 of the present invention.

[0035] Figure 13 This is a diagram showing the oil-water separation results of Examples 14 to 22 of the present invention.

[0036] Figure 14 This is a diagram showing the oil-water separation results of Examples 14, 23, and 27 of the present invention.

[0037] Figure 15 This is a diagram showing the oil-water separation results of Examples 28 to 30 of the present invention.

[0038] Figure 16 This is a diagram showing the oil-water separation results of Examples 31-33 of the present invention. DETAILED DESCRIPTION

[0039] In order to make the purposes, features, and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0040] Example 1:

[0041] The melamine foam material was cut into small rectangular pieces of 1.5 cm × 1.0 cm × 0.5 cm and ultrasonically treated in a 75% ethanol solution for 20 min to obtain the cleaned melamine foam. 0.09 g of sucrose and 0.6 g of dopamine were dissolved in 60 mL of 0.1 M tris(hydroxymethylaminomethane)-hydrochloric acid buffer solution and the pH was adjusted to 8 to obtain a mixed solution. The cleaned melamine foam was soaked in the mixed solution for 12 hours at 45°C to obtain a renewable oil-water separation material.

[0042] Comparative Example 1:

[0043] The melamine foam material was cut into small rectangular blocks of 1.5 cm × 1.0 cm × 0.5 cm and ultrasonically treated in a 75% ethanol solution for 20 min to obtain cleaned melamine foam.

[0044] Comparative Example 2:

[0045] The melamine foam material was cut into small rectangular pieces of 1.5 cm × 1.0 cm × 0.5 cm and ultrasonically treated in a 75% ethanol solution for 20 min to obtain the cleaned melamine foam; 0.6 g of dopamine was dissolved in 60 mL of 0.1 M tris(hydroxymethylaminomethane)-hydrochloric acid buffer solution and the pH was adjusted to 8 to obtain a mixed solution; the cleaned melamine foam was soaked in the mixed solution for 12 hours at 45°C to obtain a polydopamine-coated melamine material.

[0046] The surfaces of the materials obtained in Comparative Example 1, Comparative Example 2 and Example 1 were analyzed using a scanning electron microscope (SEM). Figure 1 As shown in FIG. 1 , the surface of the melamine foam after cleaning in Comparative Example 1 is relatively smooth overall; Figure 2 As shown in FIG, after polydopamine is loaded on the support material, the surface of the polydopamine-coated melamine material of Comparative Example 2 has a large number of granular protrusion structures; Figure 3 As shown, in addition to a large number of granular protrusions on the surface of the melamine foam material of Example 1, most of the pores are also covered with a thin film.

[0047] The materials obtained in Comparative Example 2 and Example 1 were tested for contact angle, and the results were as follows: Figure 4 As shown, after polydopamine is uniformly loaded on the surface of the melamine foam material, the underwater oil contact is 155° regardless of whether it contains sucrose, indicating that the polydopamine-coated melamine material of Comparative Example 2 and the renewable oil-water separation material of Example 1 both have underwater superoleophobic structures.

[0048] The hydrophilicity test of the renewable oil-water separation material of Example 1 was conducted. A water droplet was gradually brought close to the surface of the material. The water droplet was dropped onto the surface of the material using a syringe needle. The water droplet was quickly adsorbed by the surface of the material and spread out (see Figure 5 Place the material underwater, drop oil onto the surface of the material with a syringe needle, and then pull up the syringe needle. During the pulling process, the oil drop will be desorbed along with the syringe needle (see Figure 6 ), no oil droplets remained on the material surface, and there was no obvious surface adsorption phenomenon. This shows that the renewable oil-water separation material of Example 1 has superhydrophilic and underwater superoleophobic properties.

[0049] Example 2-5:

[0050] On the basis of Example 1, other conditions were not changed, and only the concentration of sucrose was changed to obtain a series of renewable oil-water separation materials, and their specific parameters are shown in Table 1.

[0051] Table 1 Parameters of different sucrose concentrations

[0052]

[0053] The renewable oil-water separation materials of Examples 2-5 were tested for underwater oil contact angles. The results are as follows: Figure 7 As shown in Figure 3, the contact angle decreases slightly with the increase of sucrose content, which indicates that the hydrophilicity decreases with the increase of sucrose content.

[0054] Examples 6-8:

[0055] Based on Example 1, a series of renewable oil-water separation materials were obtained by simply changing the concentration of dopamine. The specific parameters of the materials are shown in Table 2.

[0056] Table 2 Parameters of different dopamine concentrations

[0057]

[0058] The renewable oil-water separation materials of Examples 6-8 were tested for underwater oil contact angles, and the results are shown in Table 1. Figure 8 ,It can be seen from the figure that the increase of dopamine content has little effect on the contact angle.

[0059] Examples 9-11:

[0060] Based on Example 1, a series of renewable oil-water separation materials were obtained by simply changing the pH value of the mixed solution. The specific parameters of the materials are shown in Table 3.

[0061] Table 3 Parameters at different pH values

[0062]

[0063] The renewable oil-water separation materials of Examples 9-11 were tested for underwater oil contact angles. The results are as follows: Figure 9 As shown in the contact angle data, it can be seen that when the pH increases from 7 to 10, the contact angle first increases and then decreases; at a pH of 8, the contact angle is the largest, indicating that the hydrophilicity is the best at this time.

[0064] Examples 12-13:

[0065] On the basis of Example 1, a series of renewable oil-water separation materials were obtained by simply changing the immersion temperature of the cleaned melamine foam in the mixed solution. The specific parameters of the materials are shown in Table 4.

[0066] Table 4 Parameters at different temperatures

[0067]

[0068] The underwater oil contact angle test of the renewable oil-water separation materials of Example 12 and Example 13 is as follows: Figure 10 As shown in the contact angle data, it can be seen that the contact angle does not change much when the reaction temperature is 30℃ and 45℃; but when the reaction temperature is increased to 60℃, the contact angle decreases, indicating that the hydrophilicity of the material decreases at high temperature.

[0069] Examples 14-22:

[0070] Petroleum ether was dyed red with Sudan dye, and then mixed with water in a ratio of 1:9 to obtain an oil-water mixture; the renewable oil-water separation material prepared in the same manner as in Example 1 was used as a separation membrane and installed on a separator, wherein the structure of the separator is as follows: Figure 11 As shown; 100mL of oil-water mixture was poured into the separator from the top to conduct the oil-water separation experiment. The separation process is as follows Figure 12 shown.

[0071] By simply changing the type of oil to conduct oil-water separation experiments, a series of different separation flux and separation efficiency data can be obtained. The specific parameters are shown in Table 5.

[0072] Table 5 Specific parameters of different oil-water mixtures

[0073]

[0074] Repeat the oil-water separation experiments of Example 14 to Example 22 10 times, and calculate the average separation flux and separation efficiency. The results are as follows: Figure 13 The results show that the separation flux of all oils is between 5.0×10 4 -1.3×10 5 When separating n-hexane / water mixture, the maximum water flux can reach 1.2×10 5 Liters per square meter per hour. The average separation flux of crude oil also reached 9.3×10 4 Liters per square meter per hour. For refrigeration oil and edible oil with high viscosity (such as corn oil, soybean oil, olive oil), the average separation flux is higher than 6.0×10 4 liters per square meter per hour. Furthermore, the average separation efficiency of all materials after 10 separations was above 99.2%, with minimal fluctuation in the separation efficiency for most oils. This demonstrates that the renewable oil-water separation material prepared by the method of Example 1 has a wide range of oil-water separation capabilities.

[0075] Examples 23-27:

[0076] On the basis of Example 14, by simply changing the number of separations to conduct oil-water separation experiments, a series of different separation flux and separation efficiency data can be obtained, and the specific parameters are shown in Table 6.

[0077] Table 6 Specific parameters for separation of petroleum ether / water mixture at different times

[0078]

[0079] After every 10 separations, the average separation flux and separation efficiency were calculated. Figure 14 As shown in the figure, as the number of separations increases, the separation flux increases from 7.5×10 4liters per square meter per hour dropped to 5.1×10 4 liters per square meter per hour. Separation efficiency also showed a downward trend with increasing separation times, but the separation efficiency was always above 99.5%. This is related to the increase in separation times and the contamination of the renewable oil-water separation material surface with oil.

[0080] Examples 28-30:

[0081] Based on Example 14, after 10 repetitions of the oil-water separation experiment, the renewable oil-water separation material was completely immersed in a 75% ethanol solution for 30 minutes (i.e., the renewable oil-water separation material was cleaned with the ethanol solution). The oil-water separation experiment was then repeated 10 times. By varying the number of cleaning cycles, a range of separation flux and efficiency data were obtained. The specific parameters are shown in Table 7.

[0082] Table 7 Specific parameters of ethanol solution cleaning after oil-water separation of petroleum ether / water mixture

[0083]

[0084] After each cleaning with ethanol solution, 10 oil-water separation experiments were performed, and then the separation flux and separation efficiency were calculated. Figure 15 As shown, it shows that after 10 separations, washing with ethanol solution can effectively remove the oil stains on the surface of the renewable oil-water separation material, and the separation flux and separation efficiency of the renewable oil-water separation material can be effectively maintained, which proves the renewable characteristics of the renewable oil-water separation material.

[0085] Examples 31-33:

[0086] Based on Example 20, after 10 repetitions of the oil-water separation experiment, the renewable oil-water separation material was completely immersed in a 75% ethanol solution for 30 minutes (i.e., the renewable oil-water separation material was cleaned with the ethanol solution). The oil-water separation experiment was then repeated 10 times. By varying the number of cleaning cycles, a range of separation flux and efficiency data were obtained. The specific parameters are shown in Table 8.

[0087] Table 8 Specific parameters of ethanol solution cleaning after oil-water separation of corn oil / water mixture

[0088]

[0089] After each washing with ethanol solution, oil-water separation was performed 10 times, and then the separation flux and separation efficiency were calculated. Figure 16 As shown in the figure, it can be seen that the renewable oil-water separation material was washed with ethanol solution and then subjected to oil-water separation. This was repeated three times, and the separation flux increased from 6.2×10 4liters per square meter per hour decreased slightly to 5.5×10 4 liters per square meter per hour, while the separation efficiency remains basically unchanged. This shows that the renewable oil-water separation material has good regeneration ability and can be reused for oil-water separation.

[0090] In the above embodiments, the water flux in the oil-water separation process is calculated using formula (1), and the oil-water separation efficiency in the oil-water separation process is calculated using formula (2).

[0091]

[0092] in, V Indicates the volume of water passing through the separator in liters; S It represents the effective cross-sectional area of the oil-water separation material during the separation process, in square meters; t Indicates the time for oil-water separation in hours.

[0093]

[0094] in, C f Indicates the weight of the oil after separation, C 0 Indicates the weight of the oil before separation.

[0095] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for preparing a renewable oil-water separation material, characterized in that: The following steps are involved: mixing sucrose, dopamine and tris-hydrochloric acid buffer solution to obtain a mixed solution; soaking the melamine foam material in the mixed solution to obtain a renewable oil-water separation material; The pH of the tris-hydrochloric acid buffer solution is 7-10; the mass concentration of sucrose in the mixed solution is 0.15%-1%; When the melamine foam material is immersed in the mixed solution, the temperature of the mixed solution is 30-45° C., and the immersion time is 4-24 hours.

2. The method according to claim 1, characterized in that The mass concentration of dopamine in the mixed solution is 1%-5%.

3. The method according to claim 1, characterized in that The concentration of the Tris-hydrochloric acid buffer solution is 0.1-0.2M.

4. A renewable oil-water separation material, characterized in that: The renewable oil-water separation material is obtained by the preparation method of any one of claims 1 to 3.

5. Use of the renewable oil-water separation material according to claim 4 in oil-water separation.

6. An oil-water separation method, characterized in that: The following steps are involved: placing an oil-water mixture on one side of the renewable oil-water separation material according to claim 4; The water in the oil-water mixture is passed through the renewable oil-water separation material under the action of a driving force.

7. The oil-water separation method according to claim 6, characterized in that: The oil in the oil-water mixture is one or more of n-hexane, benzoic acid, petroleum ether, crude petroleum oil, refrigeration oil, paraffin oil, corn oil, soybean oil, and olive oil.

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