Spiropyrane ionic liquid microemulsion for reversible capture of visible light regulation and control carbon dioxide

Abstract

The invention provides a spiropyrane ionic liquid microemulsion for reversible capture of carbon dioxide regulated and controlled by visible light. The microemulsion system can reversibly capture carbon dioxide under irradiation of extra visible light. The micro-emulsion takes water as a polar phase, sec-butyl alcohol as a non-polar phase and photoresponsive spiropyrane ionic liquid as an emulsifier to form a stable pyrane ionic liquid micro-emulsion, so that the micro-emulsion liquid drops and the spiropyrane ionic liquid can be used for synergistically trapping carbon dioxide, and in a natural environment, the carbon dioxide can be effectively absorbed by the micro-emulsion liquid drops and the spiropyrane ionic liquid. After extra visible light irradiation, a microemulsion system can trigger demulsification to generate phase separation and release carbon dioxide, and then the system is irradiated by ultraviolet light to realize emulsification to form a microemulsion which is repeatedly used for carbon dioxide capture.

Description

Technical Field

[0001] This invention belongs to the field of reversible carbon dioxide capture technology, specifically relating to a type of spiropyran ionic liquid microemulsion for visible light-controlled reversible carbon dioxide capture. Background Technology

[0002] The efficient and low-energy capture and release of carbon dioxide is a key technological challenge in addressing climate change. Traditional absorbents (such as amine solutions) are often limited by high regeneration energy consumption, solvent evaporation and degradation, and corrosiveness, necessitating the development of novel intelligent capture materials. Photoresponsive materials have attracted considerable attention due to their ability to remotely and precisely control their physicochemical properties through clean light energy. Among them, spiropyran compounds can undergo reversible spirocyclic transformation under ultraviolet / visible light irradiation. Cyanide isomerization provides an ideal platform for constructing stimulus-responsive systems. Microemulsions, with their large oil / water interface and thermodynamic stability, offer a high specific surface area microenvironment for gas capture. Ionic liquids, due to their extremely low volatility, high thermal stability, and designable chemical structures, show potential in the field of carbon dioxide capture. However, traditional ionic liquid-based capture systems still face problems such as high viscosity, limited diffusion, and high regeneration energy consumption, and lack convenient on / off control mechanisms. To address these challenges, this invention innovatively integrates photoresponsive spiropyran ionic liquids, microemulsion technology, and carbon dioxide capture. Utilizing a spiropyran ionic liquid with a specific structure as an emulsifier, a photocontrolled microemulsion system is constructed for reversible carbon dioxide capture, opening a new avenue for developing next-generation low-energy, recyclable, and intelligently controllable carbon dioxide capture technologies.

[0003] Patent document CN201410658556.X discloses a method for capturing carbon dioxide using an ionic liquid / ether-based polymer composite system. This system utilizes proton transfer to introduce amide groups into the ionic liquid, leveraging the enhanced interaction between the negatively charged amide groups and carbon dioxide gas to increase the capture capacity. Furthermore, the electron-withdrawing property of the ketone carbonyl group on the anion is used to improve the desorption performance of the ionic liquid. Non-volatile polymers such as polyethylene glycol or polyether are used as diluents to accelerate the reaction rate between the ionic liquid and carbon dioxide, thereby achieving efficient, high-capacity, and reversible capture of carbon dioxide. This patent document does not involve spiropyran ionic liquid microemulsions for reversible carbon dioxide capture regulated by visible light.

[0004] Patent document CN202311421667.4 discloses a type of photoresponsive Pickering emulsion synergistically stabilized by a spiropyran ionic liquid and UiO-66-NH2. This Pickering emulsion comprises an oil-water two-phase system, with the spiropyran ionic liquid and the metal-organic framework material UiO-66-NH2 as stabilizers. The stable Pickering emulsion can demulsify under additional visible light irradiation, and upon further ultraviolet light irradiation, the system can re-emulsify to form a stable Pickering emulsion. This Pickering emulsion can be used for the Click reaction of hydrophilic azide compounds and terminal alkyne compounds. Through reversible visible and ultraviolet light modulation, the catalyst and spiropyran ionic liquid can be recycled, showing application value in drug controlled release and sustainable catalysis. This patent document does not involve visible light-controlled reversible carbon dioxide capture, and the photoresponsive Pickering emulsion reported in this patent document contains UiO-66-NH2.

[0005] References J. Am. Chem. Soc. 2023, 145, 26720-26727 report the photo-controlled reversible capture of carbon dioxide by spiropyran in a mixed solvent of water and DMSO; references Chem. Mater. 2024, 36, 1308–1317 report that preferential solvation of spiropyran by aprotic solvent molecules leads to a 60% increase in pH adjustment, providing a method to bypass the complex structural modification of photoacid molecules for photo-driven carbon dioxide capture; references J. Phys. Chem. Lett. 2024, 15, 7782-7787 report the photo-controlled reversible capture of carbon dioxide by sulfonic acid-functionalized spiropyran in ethanolamine. Among these publications, J. Am. Chem. Soc. 2023, 145, 26720-26727 reported the optimal system with a maximum carbon dioxide capture capacity of 0.8 mol / mol spiropyran. The other two works only analyzed the feasibility in principle and did not focus on the practicality of the system. Although these publications all utilized the release and capture of protons in the photoisomerization of spiropyran to regulate the capture and release of carbon dioxide, they did not consider spiropyran as a functional group of the ionic liquid. These spiropyrans lack emulsifying ability and cannot form microemulsions, thus lacking the synergistic capture of droplets in the microemulsion system, and consequently, failing to achieve a higher capture capacity. This is significantly different from the present invention, which simultaneously integrates spiropyran photoresponsiveness, ionic liquid emulsifier, and microemulsion interface for synergistic carbon dioxide capture. Summary of the Invention

[0006] The purpose of this invention is to provide a type of spiropyran ionic liquid microemulsion for visible light-controlled reversible carbon dioxide capture. This spiropyran ionic liquid microemulsion has the characteristics of high carbon dioxide capture capacity, low desorption energy consumption, and good cycle performance, and is a sustainable low-energy carbon dioxide capture system.

[0007] To achieve the above objectives, this invention employs the following technical solution: a type of spiropyran ionic liquid microemulsion for visible light-controlled reversible carbon dioxide capture. It uses a photoresponsive spiropyran ionic liquid as an emulsifier, water as a polar phase, and an organic solvent immiscible with water as a non-polar phase to form a stable spiropyran ionic liquid microemulsion. Under natural conditions, the microemulsion droplets and the spiropyran ionic liquid synergistically capture carbon dioxide. Additional visible light irradiation can trigger the demulsification of the spiropyran ionic liquid microemulsion, thereby releasing carbon dioxide. Further ultraviolet light irradiation allows the system to re-emulsify and form a microemulsion to recapture carbon dioxide.

[0008] The spiropyran ionic liquid has one or more of the following structures:

[0009]

[0010] The organic solvent is sec-butanol.

[0011] Furthermore, the spiropyran ionic liquid is a cationic ionic liquid, with the spiropyran functional group in the cationic structure, and the site of spiropyran functionalization is the oxygen atom of the chromene structure.

[0012] Further specifying, the spiropyran ionic liquid is preferably [SP-OC4mim]Br, [SP-OC6mim]Br, or [SP-OC... 10 One or more of [SP-OC6mim]Br, [SP-OC6TMA]Br, [SP-OC6DMEA]Br and [SP-OC6TMDEA]Br; more preferably [SP-OC6mim]Br.

[0013] Further specified, the mass ratio of the nonpolar phase to the polar phase is 1:9 to 9:1, preferably 6:4, 5:5, 4:6, 3:7 or 2:8, and more preferably 6:4; the mass ratio of the emulsifier to the nonpolar phase is 1:20 to 60, preferably 1:60.

[0014] Further specified, the carbon dioxide capture capacity of the spiropyran ionic liquid microemulsion is 0.15 to 1.18 mol / mol spiropyran ionic liquid under the conditions of 25°C and 1 bar carbon dioxide pressure. The carbon dioxide capture capacity of the spiropyran ionic liquid microemulsion can be adjusted according to the mass ratio of the nonpolar phase to the polar phase of the microemulsion system and the amount of spiropyran ionic liquid microemulsion used.

[0015] Furthermore, the spiropyran ionic liquid microemulsion can be used to adsorb and capture low concentrations of carbon dioxide.

[0016] Furthermore, the spiropyran ionic liquid microemulsion can serve as a highly efficient carbon dioxide capture system. Through reversible visible and ultraviolet light modulation, it can achieve photocontrolled release of carbon dioxide, reversible capture, and repeated recycling of the microemulsion system.

[0017] Compared with existing technologies, this invention has the following advantages and beneficial effects: The spiropyran ionic liquid microemulsion provided by this invention has strong stability. Visible light irradiation can cause the stable microemulsion to demulsify, and further ultraviolet light irradiation can re-emulsify the system to form a stable microemulsion. The microemulsion provided by this invention can be used for efficient carbon dioxide capture and photocontrolled release. The regenerated spiropyran ionic liquid microemulsion can continue to capture carbon dioxide without reducing its adsorption capacity. The spiropyran ionic liquid microemulsion provided by this invention has the characteristics of high carbon capture capacity, low desorption energy consumption, and good cycle performance, and has application value in the field of low-energy-consumption and high-efficiency carbon dioxide capture. Attached Figure Description

[0018] Figure 1 This is a ternary phase diagram of a spiropyran ionic liquid microemulsion.

[0019] Figure 2 The appearance changes of spiropyran ionic liquid microemulsions after capturing carbon dioxide and exposure to light.

[0020] Figure 3 This is a schematic diagram illustrating the principle of reversible carbon dioxide capture using spiropyran ionic liquid microemulsions.

[0021] Figure 4 Analysis of the reasons for the differences in properties of microemulsions constructed with different nonpolar phases.

[0022] Figure 5 The particle size of the spiropyran ionic liquid microemulsion changes with carbon dioxide absorption time.

[0023] Figure 6 After capturing carbon dioxide and after light exposure, the spiropyran ionic liquid microemulsion 13 C NMR spectrum. Detailed Implementation

[0024] The following examples further illustrate the above-described content of the present invention, but it should not be construed as limiting the scope of the subject matter of the present invention to the following examples. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention.

[0025] Example 1

[0026] 0.02 g of [SP-OC6mim]Br, 1.20 g of sec-butanol, and 0.80 g of water were added to a quartz flask and stirred to form a microemulsion. Carbon dioxide was bubbled into the microemulsion at 1 bar at 25 °C for 2 hours. The microemulsion system was then stored in the dark for 2 hours. The headspace was rapidly purged with nitrogen to remove any uncaptured carbon dioxide. After irradiation with a commercially available 45W LED visible light source, headspace analysis was performed using gas chromatography. The adsorption capacity of carbon dioxide was determined to be 1.18 mol / mol of the ionic liquid [SP-OC6mim]Br.

[0027] Example 2

[0028] 0.02 g of [SP-OC6mim]Br, 1.00 g of sec-butanol, and 1.00 g of water were added to a quartz flask and stirred to form a microemulsion. Carbon dioxide was bubbled into the microemulsion at 1 bar at 25 °C for 2 hours. The microemulsion system was then stored in the dark for 2 hours. The headspace was rapidly purged with nitrogen to remove any uncaptured carbon dioxide. After irradiation with visible light, headspace analysis was performed using gas chromatography, revealing an adsorption capacity of 0.89 mol / mol of the ionic liquid [SP-OC6mim]Br.

[0029] Example 3

[0030] 0.02 g of [SP-OC6mim]Br, 0.80 g of sec-butanol, and 1.20 g of water were added to a quartz flask and stirred to form a microemulsion. Carbon dioxide was bubbled into the microemulsion at 1 bar at 25 °C for 2 hours. The microemulsion system was then stored in the dark for 2 hours. The headspace was rapidly purged with nitrogen to remove any uncaptured carbon dioxide. After irradiation with visible light, headspace analysis was performed using gas chromatography, revealing an adsorption capacity of 1.06 mol / mol of the ionic liquid [SP-OC6mim]Br.

[0031] Example 4

[0032] 0.02 g of [SP-OC6mim]Br, 0.60 g of sec-butanol, and 1.40 g of water were added to a quartz flask and stirred to form a microemulsion. Carbon dioxide was bubbled into the microemulsion at 1 bar at 25 °C for 2 hours. The microemulsion system was then stored in the dark for 2 hours. The headspace was rapidly purged with nitrogen to remove any uncaptured carbon dioxide. After irradiation with visible light, headspace analysis was performed using gas chromatography, revealing an adsorption capacity of 0.88 mol / mol of the ionic liquid [SP-OC6mim]Br.

[0033] Example 5

[0034] 0.02 g of [SP-OC6mim]Br, 0.40 g of sec-butanol, and 1.60 g of water were added to a quartz flask and stirred to form a microemulsion. Carbon dioxide was bubbled into the microemulsion at 1 bar at 25 °C for 2 hours. The microemulsion system was then stored in the dark for 2 hours. The headspace was rapidly purged with nitrogen to remove any uncaptured carbon dioxide. After irradiation with visible light, headspace analysis was performed using gas chromatography, revealing an adsorption capacity of 0.87 mol / mol of the ionic liquid [SP-OC6mim]Br.

[0035] Example 6

[0036] 0.02 g of [SP-OC6DMEA]Br, 1.20 g of sec-butanol, and 0.80 g of water were added to a quartz flask and stirred to form a microemulsion. Carbon dioxide was bubbled into the microemulsion at 1 bar at 25 °C for 2 hours. The microemulsion system was then stored in the dark for 2 hours. The headspace was rapidly purged with nitrogen to remove any uncaptured carbon dioxide. After irradiation with visible light, headspace analysis was performed using gas chromatography. The adsorption capacity of carbon dioxide was found to be 0.17 mol / mol of the ionic liquid [SP-OC6DMEA]Br, which is attributed to the strong electron-donating ability of the ionic liquid head group.

[0037] Example 7

[0038] 0.02 g of [SP-OC6TMA]Br, 1.20 g of sec-butanol, and 0.80 g of water were added to a quartz flask and stirred to form a microemulsion. Carbon dioxide was bubbled into the microemulsion at 1 bar at 25 °C for 2 hours. The microemulsion system was then stored in the dark for 2 hours. The headspace was rapidly purged with nitrogen to remove any uncaptured carbon dioxide. After irradiation with visible light, headspace analysis was performed using gas chromatography. The adsorption capacity of carbon dioxide was found to be 0.15 mol / mol of the ionic liquid [SP-OC6TMA]Br, which is attributed to the strong electron-donating ability of the ionic liquid head group.

[0039] Example 8

[0040] 0.022 g of [SP-OC6TMDEA]Br, 1.20 g of sec-butanol, and 0.80 g of water were added to a quartz flask and stirred to form a microemulsion. Carbon dioxide at 1 bar was bubbled into the microemulsion at 25 °C for 2 hours. The microemulsion system was then stored in the dark for 2 hours. The headspace was rapidly purged with nitrogen to remove any uncaptured carbon dioxide. After irradiation with visible light, headspace analysis was performed using gas chromatography. The adsorption capacity of carbon dioxide was found to be 0.39 mol / mol of the ionic liquid [SP-OC6TMDEA]Br, which is attributed to the strong electron-donating ability of the ionic liquid head group.

[0041] Example 9

[0042] 0.02 g of [SP-OC4mim]Br, 1.20 g of sec-butanol, and 0.80 g of water were added to a quartz flask and stirred to form a microemulsion. Carbon dioxide at 1 bar was bubbled into the microemulsion at 25 °C for 2 hours. The microemulsion system was then stored in the dark for 2 hours. The headspace was rapidly purged with nitrogen to remove any uncaptured carbon dioxide. After irradiation with visible light, headspace analysis was performed using gas chromatography, revealing an adsorption capacity of 1.09 mol / mol of the ionic liquid [SP-OC4mim]Br.

[0043] Example 10

[0044] 0.022 g of [SP-OC4mim]Br, 1.20 g of sec-butanol, and 0.80 g of water were added to a quartz flask and stirred to form a microemulsion. Carbon dioxide was bubbled into the microemulsion at 1 bar at 25 °C for 2 hours. The microemulsion system was then stored in the dark for 2 hours. The headspace was rapidly purged with nitrogen to remove any uncaptured carbon dioxide. After irradiation with visible light, headspace analysis was performed using gas chromatography, revealing an adsorption capacity of 0.82 mol / mol of the ionic liquid [SP-OC4mim]Br.

[0045] Example 11

[0046] 0.02 g of [SP-OC6mim]Br, 1.20 g of sec-butanol, and 0.80 g of water were added to a quartz flask and stirred to form a microemulsion. A 1 bar carbon dioxide / nitrogen mixture (3:7, v / v) was bubbled into the microemulsion at 25 °C for 2 hours. The microemulsion system was then stored in the dark for 2 hours. Uncaptured carbon dioxide was removed by rapid headspace purging with nitrogen. After visible light irradiation, headspace analysis was performed using gas chromatography, revealing an adsorption capacity of 0.21 mol / mol of the ionic liquid [SP-OC6mim]Br.

[0047] Example 12

[0048] 0.02 g of [SP-OC6mim]Br, 1.20 g of sec-butanol, and 0.80 g of water were added to a quartz flask and stirred to form a microemulsion. A 1 bar carbon dioxide / nitrogen mixture (1:1, v / v) was bubbled into the microemulsion at 25 °C for 2 hours. The microemulsion system was then stored in the dark for 2 hours. Uncaptured carbon dioxide was removed by rapid headspace purging with nitrogen. After irradiation with visible light, headspace analysis was performed using gas chromatography, revealing an adsorption capacity of 0.70 mol / mol of the ionic liquid [SP-OC6mim]Br.

[0049] Example 13

[0050] 0.02 g of [SP-OC6mim]Br, 1.20 g of sec-butanol, and 0.80 g of water were added to a quartz flask and stirred to form a microemulsion. A 1 bar carbon dioxide / nitrogen mixture (7:3, v / v) was bubbled into the microemulsion at 25 °C for 2 hours. The microemulsion system was then stored in the dark for 2 hours. Uncaptured carbon dioxide was removed by rapid headspace purging with nitrogen. After visible light irradiation, headspace analysis was performed using gas chromatography, revealing an adsorption capacity of 0.85 mol / mol of the ionic liquid [SP-OC6mim]Br.

[0051] Example 14

[0052] 0.04 g of [SP-OC6mim]Br, 1.20 g of sec-butanol, and 0.80 g of water were added to a quartz flask and stirred to form a microemulsion. Carbon dioxide was bubbled into the microemulsion at 1 bar at 25 °C for 2 hours. The microemulsion system was then stored in the dark for 2 hours. The headspace was rapidly purged with nitrogen to remove any uncaptured carbon dioxide. After irradiation with visible light, headspace analysis was performed using gas chromatography, revealing an adsorption capacity of 0.72 mol / mol of the ionic liquid [SP-OC6mim]Br.

[0053] Example 15

[0054] 0.06 g of [SP-OC6mim]Br, 1.20 g of sec-butanol, and 0.80 g of water were added to a quartz flask and stirred to form a microemulsion. Carbon dioxide was bubbled into the microemulsion at 1 bar at 25 °C for 2 hours. The microemulsion system was then stored in the dark for 2 hours. The headspace was rapidly purged with nitrogen to remove any uncaptured carbon dioxide. After irradiation with visible light, headspace analysis was performed using gas chromatography, revealing an adsorption capacity of 0.57 mol / mol of the ionic liquid [SP-OC6mim]Br.

[0055] Example 16

[0056] 0.08 g of [SP-OC6mim]Br, 1.20 g of sec-butanol, and 0.80 g of water were added to a quartz flask and stirred to form a microemulsion. Carbon dioxide was bubbled into the microemulsion at 1 bar at 25 °C for 2 hours. The microemulsion system was then stored in the dark for 2 hours. The headspace was rapidly purged with nitrogen to remove any uncaptured carbon dioxide. After irradiation with visible light, headspace analysis was performed using gas chromatography, revealing an adsorption capacity of 0.50 mol / mol of the ionic liquid [SP-OC6mim]Br.

[0057] Comparative Example 1

[0058] 0.02 g of [SP-OC6mim]Br and 2.00 g of water were added to a quartz flask and stirred to form an ionic liquid aqueous solution. Carbon dioxide was bubbled into the solution at 1 bar at 25 °C for 2 hours. The ionic liquid aqueous solution system was then stored in the dark for 2 hours. The headspace was rapidly purged with nitrogen to remove uncaptured carbon dioxide. After irradiation with visible light, headspace analysis was performed using gas chromatography, and the adsorption capacity of carbon dioxide was determined to be 0.30 mol / mol of the ionic liquid [SP-OC6mim]Br.

[0059] Comparative Example 2

[0060] 0.078 g of [SP-OC6mim]Br was placed in a carbon dioxide adsorbent apparatus and degassed at 80 °C. The carbon dioxide adsorption capacity was then measured at 25 °C, and the amount of carbon dioxide adsorbed was found to be 0.048 mol / mol ionic liquid.

[0061] In this invention, the core factor affecting the carbon dioxide adsorption performance of spiropyran ionic liquid microemulsions is the solvation state of the ionic liquid. Factors influencing the solvation state include the composition of the microemulsion (nature of the nonpolar phase, oil-to-water ratio), the head group structure of the ionic liquid, alkyl chain length, and light exposure. These varying factors not only affect the phase equilibrium of the microemulsion, but also... Figure 1 As shown, the difference in apparent acidity of the ionic liquid is the core factor causing the difference in adsorption capacity.

[0062] Meanwhile, the outstanding innovation of this invention lies in the first application of photoresponsive spiropyran ionic liquid microemulsions for the reversible capture of carbon dioxide, achieving carbon dioxide desorption and adsorbent recycling through light irradiation, such as... Figure 2 and Figure 3 As shown, this is a typical low-energy method. From Figure 2The color change before and after adsorption shows that the solvation properties of the microemulsion change significantly after adsorption of carbon dioxide. Figure 4 To analyze the reasons for the differences in properties of microemulsions constructed with different nonpolar relative structures, from Figure 4 It is known that the stronger the hydrophilicity of the nonpolar phase, the easier it is to form a thermodynamically stable microemulsion system. Both n-butanol and sec-butanol can form microemulsions with polar aqueous phases and emulsifiers [SP-OC6mim]Br. However, the greater the change in interfacial tension, the stronger the degree of microemulsion phase behavior regulation. There are significant differences in the degree of change in interfacial tension between the organic phase and the aqueous phase of the ionic liquid in different microemulsions before and after additional visible light irradiation. Among them, the microemulsion system formed by sec-butanol with polar aqueous phase and emulsifier [SP-OC6mim]Br changes significantly. Therefore, only microemulsions formed by selecting sec-butanol as the nonpolar phase can achieve demulsification through additional visible light irradiation, while microemulsions formed by selecting n-butanol cannot effectively achieve light-controlled demulsification.

[0063] Meanwhile, an innovative finding of this invention is the synergistic adsorption of carbon dioxide by microemulsion droplets and ionic liquids. Figure 5 It can be seen that the droplet size of the microemulsion gradually increases after adsorbing carbon dioxide, but this does not cause damage to the microemulsion properties or demulsification of the system. Figure 6 middle 13 C NMR results also showed that carbon dioxide existed in the microemulsion in the form of bicarbonate ions, which is a result of the interaction between the basicity of the ion liquid chromene structure and carbon dioxide. Simultaneously, molecular carbon dioxide was also detected in the microemulsion system, indicating that the microemulsion droplets have a binding effect on carbon dioxide. These results prove the conclusion that microemulsion droplets and ion liquid synergistically adsorb carbon dioxide. Furthermore, in Example 1 and Comparative Example 1, the mass percentage concentration of the ion liquid was the same, but Example 1 was a microemulsion system, while Comparative Example 1 was only an aqueous solution system of the ion liquid. The adsorption capacity of carbon dioxide in the microemulsion system was four times that in the aqueous solution system with the same ion liquid concentration, significantly demonstrating the high adsorption efficiency of the spiropyran ion liquid microemulsion in this invention. Examples 1 and Comparative Example 2 show that the adsorption capacity of the solvated ion liquid is greatly improved, and combined with Comparative Example 1, the synergistic effect of the microemulsion is further confirmed. This invention simultaneously integrates the photoresponsiveness of spiropyran, the ion liquid emulsifier, and the microemulsion interface to synergistically capture carbon dioxide, constructing a novel carbon dioxide capture system that is expected to show significant promise in the utilization of low-energy-consumption controllable adsorbents.

[0064] The above embodiments describe the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are only illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from the scope of the principles of the present invention, and all such changes and modifications fall within the protection scope of the present invention.

Claims

1. A type of spiropyran ionic liquid microemulsion for visible light-controlled reversible carbon dioxide capture, characterized in that: Using a photoresponsive spiropyran ionic liquid as an emulsifier, water as a polar phase, and an organic solvent immiscible with water as a nonpolar phase, a stable spiropyran ionic liquid microemulsion is formed. Under natural conditions, the microemulsion droplets and the spiropyran ionic liquid can synergistically capture carbon dioxide. Additional visible light irradiation can trigger the demulsification of the spiropyran ionic liquid microemulsion, thereby releasing carbon dioxide. Further ultraviolet light irradiation can cause the system to re-emulsify and form a microemulsion to recapture carbon dioxide. The spiropyran ionic liquid has one or more of the following structures: The organic solvent is sec-butanol.

2. The spiropyran ionic liquid microemulsion for visible light-controlled reversible carbon dioxide capture according to claim 1, characterized in that: The spiropyran ionic liquid is a cationic ionic liquid, with the spiropyran functional group in the cationic structure. The site of spiropyran functionalization is the oxygen atom of the chromene structure.

3. The spiropyran ionic liquid microemulsion for visible light-controlled reversible carbon dioxide capture according to claim 1, characterized in that: The spiropyran ionic liquid is [SP-OC4mim]Br, [SP-OC6mim]Br, [SP-OC] 10 One or more of [mim]Br, [SP-OC6TMA]Br, [SP-OC6DMEA]Br and [SP-OC6TMDEA]Br.

4. The spiropyran ionic liquid microemulsion for visible light-controlled reversible carbon dioxide capture according to claim 1, characterized in that: The mass ratio of the nonpolar phase to the polar phase is 1:9 to 9:1; the mass ratio of the emulsifier to the nonpolar phase is 1:20 to 60.

5. The spiropyran ionic liquid microemulsion for visible light-controlled reversible carbon dioxide capture according to claim 1, characterized in that: The spiropyran ionic liquid microemulsion exhibits a carbon dioxide capture capacity of 0.15–1.18 mol / mol spiropyran ionic liquid under conditions of 25°C and 1 bar carbon dioxide pressure. The carbon dioxide capture capacity of the spiropyran ionic liquid microemulsion can be adjusted according to the mass ratio of the nonpolar to polar phases in the microemulsion system and the amount of spiropyran ionic liquid used.

6. The spiropyran ionic liquid microemulsion for visible light-controlled reversible carbon dioxide capture according to claim 1, characterized in that: The spiropyran ionic liquid microemulsion can be used to adsorb and capture low concentrations of carbon dioxide.

7. The spiropyran ionic liquid microemulsion for visible light-controlled reversible carbon dioxide capture according to claim 1, characterized in that: The spiropyran ionic liquid microemulsion can serve as a highly efficient carbon dioxide capture system. Through reversible visible and ultraviolet light modulation, it can achieve photocontrolled release of carbon dioxide, reversible capture, and repeated recycling of the microemulsion system.

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