Bionic intelligent potential regulation and control wettability separation membrane and preparation and potential regulation and control method

Abstract

The invention provides a bionic intelligent potential regulation and control wettability separation membrane which comprises a net-shaped conductive substrate, the net-shaped conductive substrate is covered with polypyrrole doped with perfluoroolefin oxybenzenesulfonate radicals, the polypyrrole doped with the perfluoroolefin oxybenzenesulfonate radicals forms a salvinia natans-shaped structure on the net-shaped conductive substrate, and the salvinia natans-shaped structure is formed on the net-shaped conductive substrate. The salvinia natans-shaped structure can be reversibly converted between super-hydrophobicity and super-hydrophilicity under potential regulation and control. Inspired by the special structure and wettability of salvinia natans, the salvinia natans-imitating bionic intelligent potential regulation and control wettability separation membrane is provided, the salvinia natans-imitating bionic intelligent potential regulation and control wettability separation membrane is prepared by doping perfluoroolefin oxybenzene sodium sulfonate and utilizing a simple electrochemical oxidation method, synchronous regulation and control of the surface structure and wettability can be achieved, and an intelligent oil-water separation valve is formed.

Description

Technical Field

[0001] The invention relates to the technical field of oil-water separation membranes, and in particular to a bionic intelligent potential-regulated wettability separation membrane and a preparation and potential-regulating method thereof. Background Art

[0002] Frequent oil spills and industrial production have led to an increasing discharge of oily wastewater, posing a huge threat to the environment and human health, while also bringing higher energy consumption and a greater economic burden for water purification. The recovery and separation of oily wastewater is imminent, and membrane separation technology is an important means of treating oily wastewater. Organisms in nature adapt to the environment better through perfect surface structures and special functions. In recent years, research on biological structures has increased, and the development of material structures has increasingly drawn on the characteristics of these biological surfaces. As a semi-aquatic plant, Salvinia has formed a complex layered structure on its surface to maintain a stable and lasting air layer to ensure survival. Different species of Salvinia show different wettability due to different surface structures. By regulating the surface structure of Salvinia, the transformation of surface properties can be achieved, potentially improving the performance of the material. Smart materials show great potential in this regard, and can respond to external stimuli (such as pH, electric field, temperature, CO2, light, etc.) to change surface properties and achieve reversible conversion between superhydrophobic and superhydrophilic.

[0003] However, traditional bionic materials mostly remain at the stage of structural imitation, and it is difficult to achieve dynamic simulation of biological properties, which limits their performance and application range. Therefore, studying biological structures while achieving dynamic simulation of biological properties is crucial to promote the development of bionic wetting materials. Summary of the invention

[0004] In order to solve the above technical problems, inspired by the special structure and wettability of Salvinia salvinia, the present invention provides a bionic intelligent potential-regulated wettability separation membrane imitating Salvinia salvinia, which is prepared by doping sodium perfluoroolefinoxybenzenesulfonate and utilizing a simple electrochemical oxidation method. It can achieve synchronous regulation of surface structure and wettability to constitute an intelligent oil-water separation valve.

[0005] The specific technical scheme is as follows: A bionic intelligent potential-regulated wettability separation membrane comprises a mesh conductive substrate, the mesh conductive substrate is covered with polypyrrole doped with perfluoroolefinoxybenzenesulfonate, the polypyrrole doped with perfluoroolefinoxybenzenesulfonate forms a water-leaf-like structure on the mesh conductive substrate, and the water-leaf-like structure can be reversibly converted between super-hydrophobic and super-hydrophilic under potential regulation.

[0006] Preferably, the mesh-shaped conductive substrate is a stainless steel mesh.

[0007] Preferably, the carbon chain length of the olefin in the perfluoroolefinoxybenzenesulfonate is C7-C12.

[0008] Preferably, the perfluoroolefinoxybenzenesulfonate is perfluorononenyloxybenzenesulfonate.

[0009] A method for preparing a bionic intelligent potential-regulated wettability separation membrane comprises the following steps: S1 obtains pyrrole and perfluoroolefinoxybenzenesulfonate; S2 dissolving pyrrole and perfluorononenyloxybenzenesulfonate in a mixture of ethanol and water, wherein the molar ratio of pyrrole to perfluorononenyloxybenzenesulfonate is 3:1-1:1; S3: applying a constant current of 0.01-0.02 A cm² to the solution prepared in step S2 for electrochemical polymerization, using a mesh conductive substrate as a working electrode and a sheet conductor as a counter electrode, and the polymerization time is 25-35 min; S4 washing and drying to obtain the bionic intelligent potential-regulated wettability separation membrane.

[0010] Preferably, the volume ratio of ethanol to water in step S2 is 1:4.

[0011] Preferably, the cleaning in step S4 is performed twice with ethanol and water in sequence.

[0012] A potential control method for a bionic intelligent potential-controlled wettability separation membrane is disclosed. The bionic intelligent potential-controlled wettability separation membrane is used as a working electrode, a platinum sheet is used as a counter electrode, and a calomel electrode is used as a reference electrode. CV scanning is performed by cyclic voltammetry. During the CV scanning process, an anodic peak and a cathodic peak appear. An oxidation reaction occurs at the potential at the anodic peak, and a reduction reaction occurs at the potential at the cathodic peak. When the current is close to 0 mA, the bionic intelligent potential-controlled wettability separation membrane reaches an oxidation state and a reduction state, respectively.

[0013] Preferably, the potential for oxidation reaction is -1.0 V, and the potential for reduction reaction is 0.2 V.

[0014] The beneficial effects of the present invention are as follows: the present invention designs and prepares a bionic intelligent potential-regulated wettability separation membrane. The nanostructure of the obtained bionic intelligent potential-regulated wettability separation membrane is adjustable under redox reaction, and can be transformed between "unfolding" and "closing". Through test analysis and DFT calculation, it is confirmed that the relative configuration of the PPy chain and the doped molecule OBS changes during the oxidation reaction, which leads to changes in surface roughness and nanostructure, thereby switching the PPy-OBS membrane between the WW and CB-W wetting models. In addition, the surface composition also changes during the redox process, which promotes a wider range of switching of wettability between superhydrophilic and superhydrophobic. Therefore, the PPy-OBS membrane can achieve synchronous regulation of bionic structure and wettability, and better play its role as an intelligent gate for oil-water separation.

[0015] Specifically, the smart oil-water separation valve provided by the PPy-OBS membrane can complete 15 stable switches between "open" and "closed". In the "open" state, the membrane can achieve an oil-water separation efficiency of 98.9% and a flow rate of 35.6 Lm -2 h -1 The flux of the membrane is 0.03 W, while in the oxidized state, the membrane reaches a completely "closed" state. This work not only promotes the development of biomimetic wetting materials in the synchronous intelligent control of structure and wettability, but also provides a sufficient theoretical basis.

[0016] PPy-OBS membranes have shown significant social, economic and technical benefits in the field of oil-water separation. Socially, the membranes can effectively reduce the pollution of oily wastewater to the environment, protect aquatic ecosystems and public health, and promote the recycling of resources. Economically, the PPy-OBS membranes have high separation capacity, with a separation efficiency of 98.9% and an oil-water separation flux of 35.6 L m -2 h -1 The above significantly reduces the cost and time of water treatment, increases the economic benefits of enterprises by recycling industrial waste oil, and has broad market prospects. In terms of technology, the membrane maintains stable performance during 15 redox switching processes, showing excellent durability and low energy consumption, and can intelligently control its wettability to achieve efficient separation operations under different working conditions. These advantages make the PPy-OBS membrane a strong candidate for the new generation of oil-water separation materials with important application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them: Figure 1 The SEM morphology images of the PPy-OBS film in Example 1, wherein a is an oxidized PPy-OBS film, b is a morphology image when the Salvinia spp. is closed, c is a reduced PPy-OBS film, and (d) is a morphology image when the Salvinia spp. is opened; Figure 2 is the infrared spectrum of the stainless steel mesh and the PPy-OBS composite film in Example 1; Figure 3 Schematic diagram of the atomic structure of the PPy-OBS film in Example 1, wherein a is an oxidized PPy-OBS film, and b is a reduced PPy-OBS film; Figure 4 A flow chart for the preparation of Example 1; Figure 5Schematic diagram of static contact angle of oil / water of Example 1, wherein a is an oxidized PPy-OBS film, and b is a reduced PPy-OBS film; Figure 6 The electrical control diagram of the PPy-OBS membrane in Example 1, wherein a is the cyclic voltammetry of the PPy-OBS membrane, and b is the time-current diagram of the PPy-OBS membrane during the redox process; Figure 7 Graphs of multiple electrical control of the PPy-OBS membrane in Example 1, wherein a is a CV test curve of the PPy-OBS membrane, and b is a graph of wettability transition stability test results of the PPy-OBS membrane; Figure 8 These are diagrams of the oil-water separation performance of the PPy-OBS membrane in Example 1, wherein a is a schematic diagram of the redox PPy-OBS membrane, b is a schematic diagram of the oil-water separation of the redox PPy-OBS membrane, c is the oil-water separation efficiency of the redox PPy-OBS membrane, d is the oil-water separation flux of the redox PPy-OBS membrane, and e is a view of the oil-water mixture and the filtrate under an optical microscope. DETAILED DESCRIPTION

[0018] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention can also be implemented in other ways different from this description, and those skilled in the art can make similar generalizations without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0019] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0020] Example 1 like Figure 1-5 As shown, a bionic intelligent potential-regulated wettability separation membrane comprises a stainless steel mesh, on which is covered a polypyrrole (PPY) doped with perfluoroolefinoxybenzenesulfonate. The carbon chain length of the olefin in the perfluoroolefinoxybenzenesulfonate is C7-C12, and perfluorononenyloxybenzenesulfonate is used in this embodiment. The polypyrrole doped with perfluoroolefinoxybenzenesulfonate forms a sycamore-like structure on a mesh conductive substrate, and the sycamore-like structure can be reversibly switched between super-hydrophobicity and super-hydrophilicity under potential regulation.

[0021] A method for preparing a bionic intelligent potential-controlled wettability separation membrane The PPy-OBS membrane was prepared by electrochemical oxidation with a two-electrode DC power supply. In the two-electrode system, a clean stainless steel mesh was used as the working electrode and a stainless steel sheet was used as the counter electrode. The electrochemical polymerization process was carried out in an ethanol / water solution (the volume ratio of ethanol to water was 1:4) containing 0.1 M pyrrole and 0.1 M sodium perfluorononenyloxybenzenesulfonate (OBS), with a constant current of 0.015 Acm² and a polymerization time of 1800 seconds. Finally, the prepared PPy-OBS membrane was washed twice with ethanol and water in turn, and dried to obtain a biomimetic intelligent potential-regulated wettability separation membrane.

[0022] Potential regulation of a bionic intelligent potential-regulated wettability separation membrane The redox behavior of the membrane in NaCl solution was analyzed by cyclic voltammetry (CV) using an electrochemical workstation (CHI660). The entire redox process was carried out in 0.1 M NaCl aqueous solution, with PPy-OBS membrane, platinum sheet and saturated calomel electrode (SCE) as working electrode, counter electrode and reference electrode, respectively. The CV scan range was −1.4 V to +0.8 V, and the scan rate was 10 mVs -1 It can be seen that a pair of redox peaks appeared during the CV scan, namely the anodic peak at −1.0 V and the cathodic peak at 0.2 V, which indicates that the PPy-OBS film underwent a redox reaction at the corresponding potential (e.g. Figure 6 In addition, after 800 seconds of constant potential of −1.0 V and 0.2 V, when the current was close to 0 mA, the PPy-OBS film reached the oxidation and reduction states, respectively (as shown in Figure 6 (as shown in b).

[0023] like Figure 7 As shown in a: During multiple potential regulation, the CV scan shows that the anode peak is between -0.9 V and -1.1 V, and the cathode peak is between 0.2 V and 0.4 V. Figure 7 As shown in b, stable performance was maintained during 15 redox switching processes.

[0024] like Figure 8 As shown in a, when oxidized / reduced, the molecular structure inside the PPy-OBS film will change to a certain extent, which is specifically manifested as the doped molecule OBS - When the PPy-OBS film is oxidized, the OBS − The molecule will pass through the polar -SO3 − The F groups establish a coupling relationship with the PPy chains. This will cause the F chains to be relatively more exposed on the surface of the PPy-OBS membrane, thus forming the super-hydrophobicity of the membrane surface. Similarly, the reduction process of the PPy-OBS membrane will cause the OBS −The molecules are redirected to form hydrophilicity. It is this configuration change that leads to changes in the roughness and micro / nanostructure of the PPy-OBS film during the redox process, further causing the transition of the wetting model between the WW state and the CB-W state. At the same time, the surface composition of the PPy-OBS film also changes due to the configuration, further expanding the range of reversible switching wetting behavior and promoting its switching between superhydrophilicity and superhydrophobicity.

[0025] like Figure 8 As shown in b, when the potential of the PPy-OBS membrane is at -1 V, the PPy-OBS membrane is in an open state, allowing water to pass through the PPy-OBS membrane to achieve oil-water separation. When the potential of the PPy-OBS membrane is at 0.2 V, the PPy-OBS membrane is in an open state, that is, it stops filtering water.

[0026] like Figure 8 As shown in (c), the separation efficiency of oil and water of the PPy-OBS membrane reached 98.9% during 15 redox switching processes.

[0027] like Figure 8 As shown in (d), the oil-water separation flux of the PPy-OBS membrane reached 35.6 Lm during 15 redox switching processes. -2 h -1 above.

[0028] like Figure 8 As shown in Figure e, the optical microscope view of the oil-water mixture and the filtrate before and after PPy-OBS membrane filtration shows that the filtration effect of the PPy-OBS membrane is good.

[0029] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A bionic intelligent potential-controlled wettability separation membrane, characterized in that: The invention comprises a mesh conductive substrate, on which is covered polypyrrole doped with perfluoroolefinoxybenzenesulfonate, wherein the polypyrrole doped with perfluoroolefinoxybenzenesulfonate forms a water-leaf-like structure on the mesh conductive substrate, and the water-leaf-like structure can be reversibly switched between super-hydrophobicity and super-hydrophilicity under potential regulation.

2. According to claim 1, a bionic intelligent potential-regulated wettability separation membrane is characterized by: The mesh-shaped conductive substrate is a stainless steel mesh.

3. The bionic intelligent potential-regulated wettability separation membrane according to claim 1, characterized in that: The carbon chain length of the olefin in the perfluoroolefinoxybenzenesulfonate radical is C7-C12.

4. The bionic intelligent potential-regulated wettability separation membrane according to claim 1, characterized in that: The perfluoroalkeneoxybenzenesulfonate is perfluorononenyloxybenzenesulfonate.

5. A method for preparing a bionic intelligent potential-regulated wettability separation membrane according to any one of claims 1 to 4, characterized in that: The following steps are included: S1 obtains pyrrole and perfluoroolefinoxybenzenesulfonate; S2 dissolving pyrrole and perfluorononenyloxybenzenesulfonate in a mixture of ethanol and water, wherein the molar ratio of pyrrole to perfluorononenyloxybenzenesulfonate is 3:1-1:1; S3: applying a constant current of 0.01-0.02 A cm² to the solution prepared in step S2 for electrochemical polymerization, using a mesh conductive substrate as a working electrode and a sheet conductor as a counter electrode, and the polymerization time is 25-35 min; S4 washing and drying to obtain the bionic intelligent potential-regulated wettability separation membrane.

6. The method for preparing a bionic intelligent potential-controlled wettability separation membrane according to claim 5, characterized in that: The volume ratio of ethanol to water in step S2 is 1:

4.

7. The method for preparing a bionic intelligent potential-controlled wettability separation membrane according to claim 5, characterized in that: The cleaning in step 4 is performed by washing twice with ethanol and water in sequence.

8. A method for regulating potential of a bionic intelligent potential-regulated wettability separation membrane according to any one of claims 1 to 4, characterized in that: The bionic intelligent potential-regulated wettability separation membrane was used as the working electrode, the platinum sheet as the counter electrode, and the calomel electrode as the reference electrode. CV scanning was performed by cyclic voltammetry. An anodic peak and a cathodic peak appeared during the CV scanning process. An oxidation reaction occurred at the potential at the anodic peak, and a reduction reaction occurred at the potential at the cathodic peak. When the current was close to 0 mA, the bionic intelligent potential-regulated wettability separation membrane reached the oxidation state and the reduction state, respectively.

9. The potential control method of a bionic intelligent potential control wettability separation membrane according to claim 8, characterized in that: The potential for oxidation reaction is -1.0 V, and the potential for reduction reaction is 0.2 V.

Images