A MOF modified fabric and a preparation method thereof, which can be used in the field of gas purification and chemical protection

Abstract

The present application relates to a kind of MOF modified fabric for gas purification and chemical protection and its preparation method.The base fabric of the MOF modified fabric is one or more of cotton cloth, polyester cloth, nylon cloth, acrylic cloth, aramid cloth, and MOF is one of Zn-MOF, Zr-MOF or Fe-MOF.The preparation method includes: first using solvent-free hot-pressing method to arrange MOF on base fabric, then it is placed in certain tension and low temperature conditions and is calcined, to obtain high MOF load firmness and photoactive MOF modified fabric.The MOF modified fabric described in the present application has excellent air permeability and moisture permeability, and is suitable for gas purification and chemical protection textile field.Compared with prior art, the present application can significantly improve the load firmness and photocatalytic activity of MOF on fabric.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of functional textiles, and particularly relates to a MOF modified fabric used in the fields of gas purification and chemical protection and a preparation method thereof. BACKGROUND

[0002] The rapid development of the textile industry has increased the requirements of people on textiles, and textiles with functions such as safety and health care are more popular. In recent years, photocatalyst textiles obtained by loading photocatalysts on textiles have brought important opportunities for expanding the application fields of textiles. Photocatalyst products can generate highly active species under light, effectively oxidize toxic and harmful gases in the air, kill various bacteria and the toxins released by the bacteria, thereby realizing the functions of air purification and disinfection, and providing a solution to the problems of air pollution and chemical toxicant hazards. According to authoritative reports, 70% of human diseases are related to indoor environment, and pollutants such as formaldehyde and benzene series VOCs are the main causes of diseases such as pneumonia, leukemia and cerebral thrombosis. In addition, the rapid development of the chemical industry has derived more and more chemical species, which may be released in the form of gas or vapor during production, storage and transportation, endangering the personal safety of operating personnel; on the other hand, military protective clothing often needs to face attacks of mustard gas and the like. Photocatalyst textiles can convert these chemical toxicants into non-toxic and harmless small molecular substances with the aid of light energy, and thus have application prospects in the fields of curtains, wall cloth, vehicle textiles and chemical protective clothing for military and civilian use.

[0003] At present, the photocatalyst textiles on the market mainly use nano-TiO2 as the photocatalytic component, which is combined with textiles through methods such as loading by chemical fiber master batch or flexible loading by post-finishing. For example, Chinese Invention Patent Application No. CN201510814187.3 discloses a method for fixing photocatalyst nano-TiO2 hydrosol on a fabric and a photocatalyst fabric. However, the current photocatalyst textiles still have obvious defects, such as strong dependence of nano-TiO2 on ultraviolet light, low compatibility with textiles, which will significantly reduce the air and moisture permeability of the fabric, and low adsorption and enrichment capacity for low-concentration toxic gas, which limits the photocatalytic efficiency.

[0004] Recently, metal-organic framework (MOF) materials, as a kind of crystalline porous compound formed by metal ions or clusters and organic ligands, have attracted much attention in the field of emerging photocatalytic materials due to their rich framework structures, large specific surface area, multiple active sites, adjustable band gap structure, and easy modification. Although some researches on MOF textiles have been reported, there are still some important bottlenecks when they are applied as photocatalytic textiles. On the one hand, the loading stability of MOF on textiles is usually poor and not resistant to washing. On the other hand, the homogeneous structure of MOF limits its adsorption and activation of O2, resulting in a low efficiency of generating active species by photocatalysis. By solving these problems, it is expected to develop new photocatalytic textiles based on MOF components, which have great application prospects in gas purification and chemical protection. SUMMARY

[0005] The purpose of the present application is to provide a MOF modified fabric for gas purification and chemical protection and a preparation method thereof. The fabric is prepared by a simple two-step method of solvent-free hot pressing and low-temperature calcination with MOF (Zn-MOF, Zr-MOF or Fe-MOF, etc.) as functional particles, which has the advantages of short process flow, low cost, high MOF loading stability and high photoactivity, and has application potential in the fields of clothing, household, industrial and military textiles.

[0006] The technical solution adopted by the present application is to select appropriate solid precursors of metal salt and organic ligand, and directly finish them in the fabric by hot pressing method, and then enhance the interaction between fiber macromolecules and MOF molecules by low-temperature calcination, and affect the chemical structure and photoactivity of MOF components. The specific steps are as follows:

[0007] 1) Cut the base fabric to a certain size, soak it in deionized water for 3 h and clean repeatedly, and dry it at 40℃ for 10 h to remove impurities. Then weigh the weight of the base fabric, and then weigh the metal salt with a mass ratio of 1:10~10:1 and the organic ligand powder with a mass ratio of 1:10~10:1, respectively, grind for 5-10 min to mix the organic ligand and the metal salt thoroughly, and evenly spread them on the surface of the base fabric, wrap the above compound with thin aluminum tin paper, and hot press at a hot pressing temperature of 80~150℃ and a hot pressing pressure of 1~2 MPa for 5~30 min, clean the obtained fabric repeatedly with DMF and anhydrous ethanol, and dry it at 30~60℃ for 2~10 h to obtain a MOF pretreated fabric.

[0008] 2) Put the MOF pretreated fabric obtained in step 1) into a muffle furnace, and calcine it under a certain tension (0-100 N) and low temperature (150-250℃) for 1-180 min, then take it out and repeatedly clean the obtained fabric with DMF, anhydrous ethanol and deionized water, and then dry it at 30-60℃ for 2-10 h to obtain a MOF modified fabric.

[0009] Preferably, the base fabric used in step 1) is one or more of cotton, polyester, nylon, acrylic and aramid fabric, and the base fabric has a grammage of 10-400 g / m 2 .

[0010] Preferably, the metal salt used in step 1) is one of zinc acetate, zirconium chloride or iron chloride; and the organic ligand is one of 2-methylimidazole, terephthalic acid or trimesic acid.

[0011] Principle and advantages of the application:

[0012] As a photocatalytic material, MOF has the characteristic of high porosity, and will not affect the air permeability and moisture permeability of the textile after being combined with the textile. The solvent-free hot pressing method selected in the application has the characteristics of short process and wide applicability, and can grow different types of MOF on various base fabrics to obtain pretreated fabrics. However, the load firmness of this MOF pretreated fabric is still low, and the MOF will fall off during the cleaning process. Moreover, due to the low photoactivity of MOF itself, the photocatalytic efficiency is also at a low level. Step 2) of the application is the core step for developing high-performance MOF modified fabric. The MOF pretreated fabric is calcined under tension and low temperature, which has the advantages that: the calcination temperature is usually higher than the glass transition temperature of the fiber macromolecules in the fabric, so that the thermoplastic fiber macromolecular chains will displace during the calcination process, and new hydrogen bonds and van der Waals forces will be generated between the fiber macromolecules in the new position. Especially after calcination under tension, the fiber orientation degree is improved, the interaction between the macromolecular chains is enhanced, and the molecular size stability is increased, which is similar to the principle of fabric heat setting. Importantly, the MOF molecules will also reorganize during the calcination process, and further combine with the active or polar groups in the fiber macromolecules through coordination, hydrogen bonding and other ways, greatly increasing the load firmness of the MOF on the fabric. On the other hand, due to the influence of the active / polar groups in the fiber macromolecules and the space hindrance of the fabric, the MOF molecular structure is easily distorted during the calcination process, resulting in defects, vacancies and unsaturated metal sites, thereby breaking the charge balance of the MOF molecular structure, promoting the adsorption and activation of O2, and ultimately generating more active oxygen species to improve the gas purification efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 SEM images of Comparative Examples 1 and 2 and Example 1 of the present application.

[0014] Figure 2 Comparison of air permeability data of Comparative Examples 1 and 2 and Examples 1 and 2 of the present application.

[0015] Figure 3 Comparison of moisture permeability data of Comparative Examples 1 and 2 and Examples 1 and 2 of the present application.

[0016] Figure 4 Comparison of formaldehyde purification data of Comparative Examples 1 and 2 and Examples 1 and 2 of the present application.

[0017] Figure 5 Comparison of 2-chloroethyl ethyl sulfide purification data of Comparative Examples 1 and 2 and Examples 1 and 2 of the present application.

[0018] Figure 6 Comparison of photocatalytic formaldehyde purification data of Comparative Example 2 and Example 1 of the present application before and after 5 washes.

[0019] Figure 7 Purification data of Examples 3, 4, 5 and 6 of the present application on formaldehyde under light.

[0020] Figure 8 Purification data of Examples 3, 4, 5 and 6 of the present application on 2-chloroethyl ethyl sulfide under light.

[0021] Air permeability of the fabric was tested according to GB / T 5453-1997;

[0022] Moisture permeability was tested according to GB / T 12704.1-2009;

[0023] Formaldehyde purification test conditions: gas-phase formaldehyde, initial concentration: 1 mg / L; simulated sunlight source: 300W xenon lamp, light intensity 100 mW / cm 2 ; reaction time 60 min;

[0024] 2-chloroethyl ethyl sulfide purification test conditions: liquid-phase 2-chloroethyl ethyl sulfide was tested by dissolving in n-hexane, initial concentration: 2.5 μL / mL; simulated sunlight source: 300W xenon lamp, light intensity 100 mW / cm 2 ; reaction time 30 min. DETAILED DESCRIPTION

[0025] The content of the present application will be further illustrated below in combination with examples and drawings, but these examples do not limit the protection scope of the present application. EXAMPLES

[0026] 1) Select the Terylene fabric with a grammage of 100 g / m 2 as the base fabric, cut it into 5 cm x 5 cm, soak it in deionized water for 3 h and repeatedly clean it, and dry it at 40℃ for 10 h to remove impurities. The weight of the fabric is 0.275 g, and zinc acetate with a mass ratio of 3.9:1 and 2-methylimidazole powder with a mass ratio of 9.7:1 are weighed, respectively, ground for 5 min to mix the organic ligand and the metal salt, and evenly spread on the surface of the base fabric. After the above compound is wrapped with thin aluminum tin paper, it is hot-pressed at a hot-pressing temperature of 100℃ and a hot-pressing pressure of 1.5 MPa for 10 min. After the obtained fabric is repeatedly cleaned with DMF and anhydrous ethanol, it is dried at 35℃ for 5 h to obtain a MOF pretreated fabric.

[0027] 2) The MOF pretreated fabric obtained in step 1) is placed in a muffle furnace and calcined at a tension of 10 N and a low temperature of 200℃ for 30 min. After taking it out, the obtained fabric is repeatedly cleaned with DMF, anhydrous ethanol and deionized water, and dried at 60℃ for 5 h to obtain a MOF modified fabric.

[0028] The content of Zn ions after acidolysis of the fabric is tested by inductively coupled plasma emission spectrometer (ICP-OES) technology, and the content of MOF in the fabric is calculated as 140 mg / g. Example

[0029] The tension in step 2) is adjusted to 0 N, and the rest is the same as Example One, to obtain a second MOF modified fabric. The content of Zn-MOF in the fabric is tested and calculated as 145 mg / g. Example

[0030] The cotton fabric with a grammage of 120 g / m 2 is used to replace the Terylene fabric in Example One as the base fabric, and the mass ratio of zinc acetate to fabric in step 1) is adjusted to 3.3:1, and the mass ratio of 2-methylimidazole to fabric is adjusted to 8.2:1. The calcination temperature in step 2) is adjusted to 150℃, and the rest is the same as Example One, to obtain a third MOF modified fabric. The content of Zn-MOF in the fabric is tested and calculated as 175 mg / g. Example

[0031] The Terylon-cotton fabric with a grammage of 100 g / m 2 is used to replace the Terylene fabric in Example One as the base fabric, and the mass ratio of zinc acetate to fabric in step 1) is adjusted to 3.6:1, and the mass ratio of 2-methylimidazole to fabric is adjusted to 9:1. The rest is the same as Example One, to obtain a fourth MOF modified fabric. The content of Zn-MOF in the fabric is tested and calculated as 151 mg / g. Example

[0032] The aramid fabric with a grammage of 72 g / m 2 was used to replace the polyester fabric in Example 1 as the base fabric, and the mass ratio of zinc acetate to fabric in Step 1 was adjusted to 5:1, and the mass ratio of 2-methylimidazole to fabric was adjusted to 10:1, and the rest was the same as Example 1, to obtain a fourth MOF modified fabric. The content of Zn-MOF in the fabric was tested and calculated to be 122 mg / g. Example

[0033] The metal salt in Step 1 of Example 1 was adjusted from zinc acetate to zirconium chloride, and the organic ligand was adjusted from 2-methylimidazole to terephthalic acid. The mass ratio of zirconium chloride to fabric was adjusted to 3.5:1, and the mass ratio of terephthalic acid to fabric was adjusted to 8.8:1, and the rest was the same as Example 1, to obtain a fifth MOF modified fabric. The content of Zr-MOF in the fabric was tested and calculated to be 161 mg / g.

[0034] Comparative Example 1 was a polyester fabric cleaned and dried with deionized water to remove impurities, and not subjected to MOF modification treatment. Comparative Example 2 was the polyester fabric subjected to Step 1 in Example 1, and not subjected to Step 2.

[0035] Figure 1 It was shown that the surface of Comparative Example 1 was relatively smooth, and a large number of particles appeared on the surface of Comparative Example 2, confirming that the MOF particles could be loaded on the surface of the fabric by the hot pressing method, but the distribution was not very uniform. Importantly, the MOF structure on the surface of Example 1 was smooth and uniformly distributed, indicating that the heat treatment in Step 2 described in the present application could significantly change the existing form of MOF on the surface of the fabric.

[0036] Figure 2 and Figure 3 It was shown that the air permeability and moisture permeability of Comparative Example 1, Comparative Example 2, Example 1 and Example 2 were very small, indicating that the Step 1 and Step 2 treatments described in the present application would not reduce the air permeability and moisture permeability of the fabric. The moisture permeability of Examples 1 and 2 was above 4000 g / (m 2 ·24h), fully meeting the requirements of moisture permeable protective clothing.

[0037] Figure 4It is shown that the comparative example one can only remove about 3% of formaldehyde under dark state and photocatalytic conditions, indicating that the original polyester fabric has only a small amount of adsorption capacity for formaldehyde. The dark state adsorption purification rate and photocatalytic purification rate of the comparative example two for formaldehyde reach 23.6% and 52.7% respectively, indicating that after the MOF is heat-pressed, the adsorption capacity of the fabric for formaldehyde is obviously improved, and the fabric has a certain photocatalytic degradation and purification capacity for formaldehyde. Compared with the comparative example two, the adsorption purification rates of the example one and two for formaldehyde do not change obviously, but the photocatalytic purification rates are greatly improved, reaching 96.3% and 76.8% respectively. This indicates that the heat treatment in the second step of the application can obviously improve the photocatalytic activity of the MOF on the fabric, and the tension applied to the fabric during heat treatment can significantly affect the photocatalytic activity.

[0038] Figure 5 It is shown that in the purification test of the mustard gas simulant 2-chloroethyl ethyl sulfide, the comparative example one, the comparative example two, the example one and the example two have similar adsorption and photoactivity results as in the formaldehyde purification test. The comparative example two after the MOF is heat-pressed shows a certain adsorption and photocatalytic purification capacity for 2-chloroethyl ethyl sulfide, and the example one and two show higher photocatalytic purification capacity, especially the example one obtained by heat treatment under tension, which has a purification rate of 97.5% for 2-chloroethyl ethyl sulfide within 30 min, providing conditions for its effective use in chemical protection.

[0039] Figure 6 It is shown that after the comparative example two is washed for 5 times, its photocatalytic purification capacity for formaldehyde is obviously reduced, indicating that the MOF after heat pressing is not firmly combined with the fabric, and there is a phenomenon of falling off during washing. Importantly, after the example one is washed for 5 times, its photocatalytic purification capacity for formaldehyde does not change obviously, and it can still remove nearly 100% of formaldehyde within 60 min. This indicates that the combination of the MOF with the fabric in the example one of the application is high in firmness, and the state of the MOF on the fabric surface is stable, which is mainly due to the heat treatment in the second step of the application, which can obviously change the state of the MOF molecules on the fabric and the force between the MOF molecules and the fabric, thereby providing necessary conditions for its practical application in gas purification or chemical protection.

[0040] Figure 7 and Figure 8 It is shown that the example three, four, five and six of the application can be used for photocatalytic purification of formaldehyde gas or 2-chloroethyl ethyl sulfide, and the removal rate reaches more than 80%, indicating that the method of the application can be applied to different types of fabric substrates and MOF molecules with different structures.

[0041] In summary, the MOF modified fabric prepared by the application has the characteristics of stable combination of MOF and fabric, and shows excellent performance in gas purification and chemical protection fields, and has obvious economic benefits in the industrial application of functional textiles.

[0042] The above only describes the preferred embodiments of the present application, and it should be pointed out that for ordinary skilled persons in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for preparing MOF-modified fabrics that can be used for gas purification and chemical protection, characterized in that, The MOF-modified fabric is prepared by solvent-free hot pressing to attach MOFs onto a base fabric, followed by calcination under certain tension and low temperature conditions. The preparation method of the MOF-modified fabric includes the following steps: 1) Cut the base fabric to a certain size, soak it in deionized water for 3 hours and wash it repeatedly, and dry it at 40°C for 10 hours to remove impurities; then weigh the base fabric, and weigh the metal salt and organic ligand powder at a mass ratio of 1:10 to 10:1 with the fabric, grind them for 5-10 minutes to fully mix the organic ligand and metal salt, and evenly coat them on the surface of the base fabric. After wrapping the above composite with thin aluminum foil, hot press it at a hot pressing temperature of 80-150°C and a hot pressing pressure of 1-2 MPa for 5-30 minutes. After repeatedly washing the obtained fabric with DMF and anhydrous ethanol, dry it at 30-60°C for 2-10 hours to obtain MOF pretreated fabric. 2) Place the MOF pretreated fabric obtained in step 1) in a muffle furnace and calcine it for 1 to 180 minutes under tension of 0 to 100 N and low temperature of 150 to 250 °C. After taking it out, repeatedly wash the obtained fabric with DMF, anhydrous ethanol and deionized water, and then dry it at 30 to 60 °C for 2 to 10 hours to obtain MOF modified fabric.

2. The preparation method according to claim 1, characterized in that, The base fabric is made of one or more blends of cotton, polyester, nylon, acrylic, and aramid fabrics, with a weight of 10–400 g / m². 2 .

3. The preparation method according to claim 1, characterized in that, The metal salt is one of zinc acetate, zirconium chloride, or ferric chloride; the organic ligand is one of 2-methylimidazole, terephthalic acid, or trimesic acid.

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