Method for recovering carbon nanotube organic dispersion liquid containing high-boiling-point alcohol impurities

Abstract

The invention discloses a method for recovering carbon nanotube organic dispersion liquid containing high-boiling-point alcohol impurities. The recovery method comprises the following steps: mixing an alcohol-polluted carbon nano tube organic dispersion liquid with a functionalized molecular sieve, and carrying out alcohol adsorption treatment, so as to realize the recovery of the carbon nano tube organic dispersion liquid. Instruments and equipment used in the recovery method are simple, low-cost and high-purity recovery can be carried out, and carbon tube loss in the recovery process is reduced; meanwhile, the recovery method disclosed by the invention has wide applicability and can be used for removing most of strong-polarity alcohol pollutants in the weak-polarity carbon tube dispersion liquid; in addition, the recovery method is environment-friendly and efficient, the use of various solvents in the recovery process is reduced, and the molecular sieve adsorbent can be reused after being treated.

Description

Technical Field

[0001] The present invention belongs to the technical field of separation and purification, and particularly relates to a method for recovering an organic dispersion of carbon nanotubes containing high-boiling alcohol impurities. Background Art

[0002] Single-walled carbon nanotubes (SWCNTs) have excellent electrical, optical, and mechanical properties, making them ideal candidates for emerging applications such as high-performance electronics, transparent electrodes, and flexible sensors. The single-walled carbon nanotube dispersion is the core material for fabricating high-performance electronic devices, and its purity and monodisperse state directly determine the orientation arrangement quality of carbon nanotubes in wafer assembly and the device performance. The single-walled carbon nanotube dispersion solution can be classified according to the type of carbon nanotubes, including single-walled carbon nanotube dispersion, single-handed carbon nanotube dispersion, metallic carbon nanotube dispersion, and semiconducting carbon nanotube dispersion.

[0003] The two-liquid-phase orientation arrangement technology is an effective method for preparing carbon nanotube orientation array films based on the organic dispersion of single-walled carbon nanotubes. The principle is that the carbon nanotube dispersion forms a stable two-liquid-phase system with a specific organic alcohol (such as butylene glycol, ethylene glycol, or glycerol), and the carbon nanotubes achieve orderly assembly on the substrate through the strong affinity between the alcohol and the substrate. However, the trace amount of alcohol remaining in the dispersion after assembly will destroy the dispersion stability of the carbon nanotubes, causing local aggregation, which seriously affects the assembly quality and the performance of the final electronic device. Therefore, the carbon nanotube dispersion cannot be directly reused.

[0004] Currently, in industry, the separation of alcohols (including ethylene glycol and 1,2-butanediol, etc.) often uses distillation processes such as ordinary distillation, vacuum distillation, azeotropic distillation, reactive distillation, and extractive distillation [3]. However, since ethylene glycol and 1,2-butanediol will form azeotropes with the organic solvents in the carbon nanotube dispersion, it is difficult to separate them, and the distillation process route has problems such as low product recovery rate, high cost, and high energy consumption.

[0005] Currently, the main method for recycling carbon nanotube dispersions is filtration and redispersion. The main steps are as follows: After thoroughly filtering the carbon nanotube dispersion, it is washed multiple times with a solvent and then redispersed in the solvent. This method has problems such as a high loss rate of carbon nanotubes, a long processing time, a large consumption of solvents, and environmental pollution. (1) Low filtration efficiency: Carbon nanotubes form a dense filter cake on the surface of the filter membrane, resulting in low filtration efficiency. The process is lengthy: The cycle of "filtration - washing - redispersion" needs to be repeated 5 - 8 times (only 20% - 30% of the solvent can be removed each time), and the total time-consuming is several hours to several days. Poor dispersion stability: After filtration, carbon nanotubes agglomerate due to van der Waals forces, and additional dispersants or ultrasonic treatment are required, further prolonging the process flow. (2) Large material loss: The irreversible loss of carbon nanotubes is serious. Loss during the washing process: Small-sized carbon nanotubes escape with the waste liquid and cannot be recovered, with a loss rate of 10% - 30%. (3) Poor environmental friendliness: There is a high risk of solvent waste and pollution. Pressure of waste liquid treatment: A large amount of solvent is required to wash the residual alcohol pollutants during filtration and washing. The solvent cannot be recycled: There is a lack of recycling design, violating the principles of green chemistry. Therefore, developing an efficient and low-loss carbon nanotube dispersion recycling technology is an urgent problem to be solved. Summary of the Invention

[0006] The main object of the present invention is to provide a method for recycling an organic dispersion of carbon nanotubes containing high-boiling alcohol impurities, so as to overcome the deficiencies of the prior art.

[0007] To achieve the foregoing invention object, the technical solutions adopted by the present invention include: An embodiment of the present invention provides a method for recycling an organic dispersion of carbon nanotubes containing high-boiling alcohol impurities, which includes: Providing an organic dispersion of carbon nanotubes contaminated with alcohol; And mixing the organic dispersion of carbon nanotubes contaminated with alcohol with a functionalized molecular sieve for alcohol adsorption treatment, thereby realizing the recycling of the organic dispersion of carbon nanotubes.

[0008] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The recycling method in the present invention uses simple equipment and can achieve low-cost and high-purity recycling; (2) The recycling method in the present invention can effectively reduce the loss of carbon nanotubes during the recycling process; (3) The recycling method in the present invention has wide applicability and can be used to remove most strongly polar alcohol pollutants from weakly polar carbon nanotube dispersions; (4) The recycling method in the present invention is environmentally friendly and efficient, reduces the use of various solvents during the recycling process, and the molecular sieve adsorbent can be reused after treatment. Description of the Drawings

[0009] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0010] Figure 1 It is a schematic diagram of a method for recovering a carbon nanotube organic dispersion containing high-boiling alcohol impurities in a typical embodiment of the present invention; Figure 2 It is the UV-VIS-NIR diagrams of the single-walled carbon nanotube trichloroethane dispersion before and after recovery in Example 1 of the present invention; Figure 3 It is the UV-VIS-NIR diagrams of the single-walled carbon nanotube toluene dispersion before and after recovery in Example 2 of the present invention. Detailed implementation manners

[0011] In view of the defects of the prior art, the inventors of this case have, through long-term research and a large number of practices, been able to propose the technical solution of the present invention. It mainly uses functionalized molecular sieves to perform highly selective adsorption separation on the alcohol-polluted single-walled carbon nanotube organic dispersion, realizing the simple and efficient recovery of the carbon nanotube dispersion, thereby obtaining a carbon tube dispersion with low loss and high purity, providing a sustainable raw material recycling solution for the large-scale manufacturing of wafer-level carbon-based electronic devices.

[0012] The following will clearly and completely describe the technical solution of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0013] Specifically, as an aspect of the technical solution of the present invention, a method for recovering a carbon nanotube organic dispersion containing high-boiling alcohol impurities includes: Providing an alcohol-polluted carbon nanotube organic dispersion; And mixing the alcohol-polluted carbon nanotube organic dispersion with functionalized molecular sieves for alcohol adsorption treatment, thereby realizing the recovery of the carbon nanotube organic dispersion.

[0014] In some preferred embodiments, the alcohol in the alcohol-polluted carbon nanotube organic dispersion includes high-boiling alcohols; wherein, the high-boiling alcohols include any one or a combination of 2-butene-1,4-diol, ethylene glycol, glycerol, isopropanol, and are not limited thereto.

[0015] In some preferred embodiments, the carbon nanotubes in the alcohol-contaminated carbon nanotube organic dispersion include any one or a combination of single-walled carbon nanotubes, double-walled carbon nanotubes, and multi-walled carbon nanotubes, and are not limited thereto.

[0016] Furthermore, the single-walled carbon nanotubes include any one or a combination of metallic carbon nanotubes, semiconducting carbon nanotubes, and single-handed chiral carbon nanotubes, and are not limited thereto.

[0017] In some preferred embodiments, the organic solvents in the alcohol-contaminated carbon nanotube organic dispersion include any one or a combination of toluene, m-chlorotoluene, 1,1,2-trichloroethane, and chloroform, and are not limited thereto.

[0018] In some preferred embodiments, the alcohol and the organic solvent in the alcohol-contaminated carbon nanotube organic dispersion are immiscible.

[0019] In some preferred embodiments, the recovery method specifically includes: at least using one of water bath sonication, magnetic stirring, and cell disruption treatment, mixing the alcohol-contaminated carbon nanotube organic dispersion with the functionalized molecular sieve and performing alcohol adsorption treatment, and then performing low-speed centrifugation. The obtained upper layer liquid is the recovered carbon nanotube organic dispersion, and the lower layer material is the functionalized molecular sieve that adsorbs alcohol.

[0020] Furthermore, the functionalized molecular sieve includes hydrophobic modified alumina and / or sulfonic acid group modified 13X molecular sieve, and is not limited thereto.

[0021] Furthermore, the stirring rate used for the magnetic stirring is 500 - 1200 rpm.

[0022] Furthermore, the temperature of the alcohol adsorption treatment is 20 - 40 °C, and the time is 10 - 60 min.

[0023] Furthermore, the centrifugal force of the low-speed centrifugation is 2000 - 10000 g, and the time is 30 min.

[0024] Furthermore, the recovery method further includes: heating and washing the functionalized molecular sieve that adsorbs alcohol, so as to realize the recycling of the functionalized molecular sieve.

[0025] In some preferred embodiments, the recovery method further includes: before performing the alcohol adsorption treatment, first performing pretreatment on the alcohol-contaminated carbon nanotube organic dispersion.

[0026] Furthermore, the pretreatment includes: removing the alcohol dispersion phase in the alcohol-contaminated carbon nanotube organic dispersion by means of suction and / or liquid separation.

[0027] In some preferred embodiments, the recovery rate of carbon nanotubes in the recovery method is above 95%.

[0028] The present invention proposes to develop an efficient and low-loss carbon nanotube dispersion recovery technology, which is based on the molecular sieve selective adsorption technology: by adding a functionalized molecular sieve that can selectively adsorb alcohol to the alcohol-contaminated single-walled carbon nanotube organic dispersion, under stirring and low-speed centrifugation, high-throughput separation of alcohol molecules and carbon nanotubes is achieved. Using the molecular sieve selective adsorption technology to treat the carbon nanotube dispersion, the recovery rate of carbon nanotubes exceeds 95%, and the residual alcohol concentration can be reduced to below 5 ppm. The recovered carbon nanotube dispersion does not require additional addition of a dispersant or other treatment, and is particularly suitable for the precise recovery and reuse of high-purity single-handed carbon nanotubes and semiconductor / metal-type carbon nanotubes. This technical system has successfully solved the key problems in the recycling of carbon nanotube dispersions, providing a sustainable raw material recycling solution for the large-scale manufacturing of wafer-level carbon-based electronic devices. The technical process is simple and convenient, with significant economic benefits and potential for industrial application.

[0029] In some preferred embodiments, the recovery method of the carbon nanotube organic dispersion containing high-boiling-point alcohol impurities (schematic diagram as Figure 1 shown) includes: (1) Pretreatment of high-boiling-point alcohol impurities: The alcohol treated by this method is immiscible with the organic solvent. For the alcohol-contaminated single-walled carbon nanotube organic dispersion, according to the different densities, the alcohol contaminants with a density less than that of the organic solvent will appear on the upper layer, and those with a large density will be on the lower layer. The alcohol is removed by means such as suction and separatory funnel.

[0030] (2) Molecular sieve adsorption process: Weigh a certain mass of functionalized molecular sieve, add it to the pretreated single-walled carbon nanotube dispersion, and stir magnetically at 500 - 1200 rpm / min until the carbon nanotubes are completely dispersed.

[0031] (3) Centrifugation removal process: Centrifuge the molecular sieve - single-walled carbon nanotube dispersion at a low speed for a certain time. Take the supernatant as the purified single-walled carbon nanotube dispersion. The lower layer is the molecular sieve adsorbed with alcohol.

[0032] (4) Molecular sieve recycling: Take the centrifuged molecular sieve precipitate and recycle it under heating and cleaning conditions.

[0033] The method in the present invention has universality and can effectively be applied to the recovery of various types of single-walled carbon nanotube dispersions; at the same time, during the purification process of the single-walled carbon nanotube organic dispersion containing high-boiling-point alcohol impurities, the alcohol is selectively adsorbed by a specific molecular sieve, and the organic solvent and single-walled carbon nanotubes are not adsorbed during the process, without affecting the stability of the single-walled carbon nanotubes in the solution.

[0034] The technical solution of the present invention will be further described in detail below in conjunction with several preferred embodiments and the accompanying drawings. These embodiments are implemented on the premise of the technical solution of the invention, and detailed implementation manners and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0035] In the following embodiments, the experimental materials used can be obtained from conventional biochemical reagent companies without special instructions.

[0036] Example 1 Pretreatment of alcohol impurities: For the single-walled carbon nanotube 1,1,2-trichloroethane dispersion contaminated by 2-butene-1,4-diol, since the density of 2-butene-1,4-diol is less than that of 1,1,2-trichloroethane and it floats on the upper layer, the upper-layer alcohol is removed by a pipette.

[0037] Molecular sieve adsorption process: Weigh a certain mass of sulfonic acid group-modified 13X molecular sieve and prepare it into 1 mg / mL, add it to the pretreated single-walled carbon nanotube 1,1,2-trichloroethane dispersion, and stir magnetically at 500 rpm / min at room temperature of 26 °C for 30 min.

[0038] Centrifugation removal process: Centrifuge the molecular sieve-single-walled carbon nanotube mixed dispersion at a low speed of 3000 g for 30 min. Take the upper-layer clear liquid as the purified single-walled carbon nanotube dispersion, and the lower layer is the molecular sieve adsorbed with alcohol.

[0039] Recycling of molecular sieve: Take the centrifuged molecular sieve precipitate, wash it several times with deionized water, and recycle it under heating and washing conditions on a hot stage at 80 °C.

[0040] The UV-VIS-NIR diagrams of the single-walled carbon nanotube trichloroethane dispersion before and after recycling in this example are as Figure 1 shown.

[0041] Example 2 Pretreatment of alcohol impurities: For the single-walled carbon nanotube toluene dispersion contaminated by 2-butene-1,4-diol, since the density of 2-butene-1,4-diol is greater than that of toluene and it sinks to the lower layer, the lower-layer alcohol is removed by a separating funnel.

[0042] Molecular sieve adsorption process: Weigh a certain mass of alumina (hydrophobic modification) molecular sieve and prepare it into 1 mg / mL, add it to the pretreated single-walled carbon nanotube toluene dispersion, and stir magnetically at 500 rpm / min at 40 °C for 10 min.

[0043] Centrifugation removal process: Centrifuge the molecular sieve-single-walled carbon nanotube mixed dispersion at a low speed of 2000 g for 30 min. Take the upper-layer clear liquid as the purified single-walled carbon nanotube dispersion, and the lower layer is the molecular sieve adsorbed with alcohol.

[0044] Recycling of molecular sieve: Take the centrifuged molecular sieve precipitate and recycle it under heating and cleaning conditions.

[0045] The UV-VIS-NIR diagrams of the single-walled carbon nanotube toluene dispersion before and after recycling in this example are as Figure 2 shown.

[0046] Example 3 Pretreatment of alcohol impurities: For the single-walled carbon nanotube m-chlorotoluene dispersion contaminated by ethylene glycol, since the density of ethylene glycol is greater than that of m-chlorotoluene and it sinks to the lower layer, the lower-layer ethylene glycol is removed through a separatory funnel.

[0047] Molecular sieve adsorption process: Weigh a certain mass of sulfonic acid group-modified 13X molecular sieve and prepare it into 1 mg / mL, add it to the pretreated single-walled carbon nanotube toluene dispersion, and magnetically stir it at 1000 rpm / min at 20 °C for 60 min.

[0048] Centrifugation removal process: Centrifuge the molecular sieve-single-walled carbon nanotube mixed dispersion at a centrifugal force of 10000g for 30 min at low speed. Take the supernatant as the purified single-walled carbon nanotube dispersion, and the lower layer is the molecular sieve adsorbed with alcohol.

[0049] In addition, the inventors of this case also referred to the foregoing examples and conducted tests with other raw materials, process operations, and process conditions described in this specification, and all obtained relatively ideal results.

[0050] It should be understood that the technical solution of the present invention is not limited to the limitations of the above specific embodiments. Any technical deformation made according to the technical solution of the present invention without departing from the spirit of the present invention and the scope protected by the claims falls within the protection scope of the present invention.

Claims

1. A method for recovering a carbon nanotube organic dispersion containing a high-boiling alcohol impurity, characterized in that: include: providing an alcohol-contaminated carbon nanotube organic dispersion; Furthermore, the alcohol-contaminated organic dispersion of carbon nanotubes is mixed with the functionalized molecular sieve for alcohol adsorption treatment, thereby realizing the recovery of the organic dispersion of carbon nanotubes.

2. The recycling method according to claim 1, characterized in that: The alcohol in the alcohol-contaminated organic dispersion of carbon nanotubes includes a high-boiling-point alcohol; wherein the high-boiling-point alcohol includes any one or more of 2-butene-1,4-diol, ethylene glycol, glycerol, and isopropanol; And / or, the carbon nanotubes in the alcohol-contaminated carbon nanotube organic dispersion include any one or more combinations of single-walled carbon nanotubes, double-walled carbon nanotubes, and multi-walled carbon nanotubes; the single-walled carbon nanotubes include any one or more combinations of metallic carbon nanotubes, semiconducting carbon nanotubes, and single-chiral carbon nanotubes; And / or, the organic solvent in the alcohol-contaminated carbon nanotube organic dispersion includes any one or more combinations of toluene, m-chlorotoluene, 1,1,2-trichloroethane, and chloroform.

3. The recycling method according to claim 1, characterized in that: The alcohol in the alcohol-contaminated carbon nanotube organic dispersion is immiscible with the organic solvent.

4. The recycling method according to claim 1, characterized in that: Specifically include: At least one of water bath ultrasound, magnetic stirring and cell disruption treatment is used to mix the alcohol-contaminated carbon nanotube organic dispersion with the functionalized molecular sieve and perform alcohol adsorption treatment, followed by low-speed centrifugation. The upper layer liquid obtained is the recovered carbon nanotube organic dispersion liquid, and the lower layer material is the functionalized molecular sieve that adsorbs alcohol.

5. The recycling method according to claim 4, characterized in that: The functionalized molecular sieve includes hydrophobically modified alumina and / or sulfonic acid group-modified 13X molecular sieve.

6. The recycling method according to claim 4, characterized in that: The stirring rate of the magnetic stirring is 500-1200 rpm; And / or, the alcohol adsorption treatment is carried out at a temperature of 20-40°C and for a time of 10-60 min; And / or, the centrifugal force of the low-speed centrifugation is 2000-10000 g, and the time is 30 min.

7. The recycling method according to claim 4, characterized in that: Also includes: The functionalized molecular sieve adsorbing alcohol is heated and washed, thereby realizing the recycling of the functionalized molecular sieve.

8. The recycling method according to claim 1, characterized in that: Also includes: Before the alcohol adsorption treatment, the alcohol-contaminated carbon nanotube organic dispersion is pre-treated.

9. The recycling method according to claim 8, characterized in that: The pretreatment comprises: removing the alcohol dispersed phase in the alcohol-contaminated carbon nanotube organic dispersion by means of absorption and / or liquid separation.

10. The recycling method according to claim 1, characterized in that: The recovery rate of carbon nanotubes in the recovery method is above 95%.

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