Preparation method of a high-loading nanolignin / selenium cigarette filter

Abstract

This patent discloses a cigarette filter tip loaded with nano-lignin / selenium and its preparation method. The method is characterized by utilizing solvent exchange and the self-reducing property of lignin to prepare organic nano-lignin / selenium composite particles with a large specific surface area, hollow structure, and small pore throats. A cellulose acetate filter tip is then immersed in this suspension, followed by freeze-drying to obtain the high-filtration cigarette filter tip loaded with nano-porous lignin / selenium. This invention can effectively remove O2 from the mainstream cigarette smoke. ‑ It removes ·NO and ·OH, as well as carbon monoxide and formaldehyde contained in cigarette smoke, without affecting the degradability of the cellulose acetate filter itself. The manufacturing process is simple, which not only reduces the harm of smoking to human health, but also does not increase the environmental pressure caused by filter degradation.

Description

Technical Field

[0001] This invention discloses a high-filtration cigarette filter tip loaded with nanoporous lignin / selenium, belonging to the field of cigarette filter tip materials. Background Technology

[0002] In recent years, smoking has become one of the main sources of reactive oxygen species and excess free radicals in the bodies of both active and passive smokers, and is a leading cause of lung cancer and chronic obstructive pulmonary disease. For example, high levels of reactive oxygen species can produce toxic side effects, oxidizing and damaging proteins, lipids, DNA, and other substances. This not only accelerates aging but also increases the risk of diseases such as tumors, cardiovascular disease, and diabetes. Furthermore, during cigarette smoking, combustion products from tobacco and byproducts, such as carbon monoxide or formaldehyde, enter the body with the mainstream smoke and accumulate in various organs, harming human health. Therefore, reducing the content of free radicals and toxic gases in mainstream smoke is crucial for improving cigarette safety and is also an essential requirement for modern society's pursuit of health.

[0003] In the last century, scientist Ernst Wynder pointed out that smoking is a significant factor in lung cancer and was the first to propose adding filters to cigarettes. After nearly a century of development, almost 100% of cigarettes sold worldwide are now filtered. However, the main material for mainstream cigarette filters is cellulose acetate, primarily used to remove some tar, heavy metals, and crotonaldehyde from cigarettes. It is difficult to effectively remove free radicals or toxic gases such as formaldehyde. Therefore, there is an urgent need to develop adsorption filters that can efficiently filter active free radicals and harmful gases. Patent CN110698685 discloses a MOF-modified cigarette filter material that can effectively remove carbon monoxide and ammonia from cigarettes, but MOF materials are expensive and complex to prepare, making large-scale application difficult. CN113068396 discloses a functional cigarette filter material containing natural plant materials and its preparation method. Natural plant particles such as rosemary, coffee, and jasmine are injected into the cigarette filter using a capsule syringe, effectively removing major components causing bad breath such as ammonia, acrolein, and crotonaldehyde. However, this injection method easily leads to particle leakage or uneven distribution. Patent CN108576924 discloses a cigarette filter with a molecular sieve-loaded structure. Through the larger physical adsorption pores of the molecular sieve, the tar, nicotine, and carbon monoxide content in cigarette smoke is significantly reduced. CN106805292 discloses a cigarette filter containing activated carbon. Its principle is similar to that of molecular sieve adsorption, effectively removing harmful gases such as carbon monoxide from smoke. However, on the one hand, the larger pores of the molecular sieve or activated carbon lead to a significant reduction in the total particulate matter, resulting in a poorer cigarette taste; on the other hand, the introduced molecular sieve or activated carbon can also worsen the filter's degradation performance, increasing environmental damage.

[0004] Compared to removing harmful gases from cigarette smoke, the removal of reactive free radicals from cigarette smoke has received relatively less attention. Patent CN109310146 discloses a cigarette filter containing algae, which can adsorb toxic components from cigarette smoke and effectively reduce ROS levels in saliva and serum. However, the algae involved are mainly sedimentary rocks composed of algae and travertine, which are relatively rare in my country and are primarily distributed in European countries such as Hungary. Patent CN106805291 discloses a cigarette filter with free radical scavenging effects. Its adsorption filter layer is mainly composed of activated carbon and lycopene, effectively removing harmful gases such as carbon monoxide and also scavenging harmful free radicals in the gas phase. However, the adsorption filter layer also requires activated carbon as a carrier.

[0005] Lignin is the second most abundant biomass component in plant cell walls after cellulose. Its main structural units are typically three phenylpropane units: p-hydroxyphenyl, guaiacol, and syringyl. It is an aromatic natural polymer rich in phenolic hydroxyl groups. The phenolic structure in lignin endows it with excellent antioxidant properties, while the carbon-carbon and ether bonds between the phenylpropane units contribute to its good stability. Currently, most lignin is derived from industrial alkali lignin produced during pulping and papermaking. Compared to native lignin from plants, due to numerous side reactions occurring during pulping and papermaking, the structural units of lignin are unevenly distributed. A large portion of its functional groups are encapsulated by its highly cross-linked three-dimensional network structure and aromatic rings, resulting in poor reactivity and low controllability. Simultaneously, lignin possesses hydrophilic hydroxyl and phenolic hydroxyl groups, as well as hydrophobic aromatic rings and methyl groups, allowing for the rearrangement of hydrophilic and hydrophobic units through self-assembly. The assembled lignin nanospheres have a larger specific surface area and a special size effect, which not only further improves the reactivity of the lignin nanospheres but also increases their adsorption capacity.

[0006] Selenium is an essential trace element for human and animal life. Nano-selenium possesses antioxidant properties and is highly efficient at scavenging free radicals in the human body. Furthermore, nano-selenium can be rapidly absorbed and utilized, alleviating blood pressure issues; it can also protect myocardial cells, easing contraction and relaxation, and protecting against ischemic and hypoxic damage to the heart; simultaneously, it can lower cholesterol, reduce the area of ​​myocardial infarction, and prevent atherosclerosis. The phenolic hydroxyl groups on lignin themselves have weak reducing properties, enabling them to reduce precious metals such as platinum and silver, forming organic nano-lignin particles loaded with precious metal nanoparticles, further enhancing their reactivity. However, it is currently unclear whether lignin has the loading capacity for nano-selenium, which has a strong free radical scavenging ability, and there is no known application of lignin in removing free radicals from cigarette smoke. Summary of the Invention

[0007] In view of this, the present invention provides a method for preparing a high-filtration cigarette filter tip loaded with nano-lignin / selenium. This method can effectively remove gases such as formaldehyde and carbon monoxide from cigarettes, and at the same time, it can efficiently capture active free radicals such as O2 generated during cigarette combustion. - , NO and OH, etc.

[0008] To achieve the above objectives, the present invention provides a method for preparing a high-filtration cigarette filter tip loaded with nano-lignin / selenium, wherein the adsorption filter layer is composed of cellulose acetate filter tip, nanoporous lignin, and nano-selenium particles. The method includes the following steps: (1) Dissolve alkali lignin in valerol, the mass of lignin being 1-20 wt% of the mass of valerol, and then add 10-20 times the mass of valerol in deionized water. Centrifuge the resulting suspension and wash it three times with deionized water, and dry it to obtain porous organic lignin nanoparticles.

[0009] (2) The porous organic lignin nanoparticles prepared in step 1 are ultrasonically dispersed in water at a mass concentration of 0.1-1 wt%, and then an equal mass of 0.01-0.1 M sodium selenite solution is added. The mixture is heated and stirred in a water bath at 80-85 ℃ for 2-3 h. The red suspension is then centrifuged and washed three times with deionized water. The mixture is then vacuum dried to obtain lignin nanoparticles loaded with selenium nanoparticles.

[0010] (3) Prepare the organic nano-lignin / selenium composite particles obtained in step 2 into a 1-10 mg / mL concentration solution, then immerse the cellulose acetate layer in the nano-composite particle suspension for 30-60 min, and then freeze-dry to obtain the loaded nanoporous lignin / selenium high-filtration cigarette filter.

[0011] Preferably, the content of porous lignin nanoparticles in the filter tip is 0.01-0.5 wt% of the cellulose acetate content; and the content of nano-selenium particles is 1-20 wt% of the lignin nanoparticle content.

[0012] Preferably, the porous organic lignin nanoparticles have a size of 100-500 nm, a pore throat size of 10-60 nm, and a selenium nanoparticle size of 1-30 nm.

[0013] The organic nano-lignin / selenium cigarette filter disclosed in this invention can be used to remove active free radicals such as O2 from mainstream cigarette smoke. - , NO, OH, and remove carbon monoxide and formaldehyde contained in flue gas.

[0014] This invention does not specify any particular procedures for centrifugation and freeze-drying; procedures well known in the field can be followed.

[0015] This invention provides a high-filtration cigarette filter loaded with nano-lignin / nano-selenium and its preparation method. First, using a solvent exchange method, lignin is self-assembled in water to form hollow nanoparticles with a large specific surface area and certain pore throats, without damaging the lignin structure. Then, utilizing the reducing property of the phenolic hydroxyl groups of natural lignin, lignin / selenium composite particles loaded with nano-selenium are prepared without the addition of an external reducing agent. Further, a regular cellulose acetate filter is impregnated and freeze-dried to obtain the high-filtration cigarette filter loaded with nano-lignin / nano-selenium. The dual strong free radical scavenging ability of lignin and selenium can effectively remove free radicals from the gas phase. Simultaneously, the large specific surface area hollow structure can capture gases such as carbon monoxide and formaldehyde, and the small pore throats do not affect the total particle size or gas resistance.

[0016] The high-filtration cigarette filter tip loaded with nano-lignin / nano-selenium provided by this invention has a simple preparation process and does not affect the degradability of the cellulose acetate filter tip itself, making it a novel green and efficient filter tip. Attached Figure Description

[0017] Figure 1 This is a schematic diagram illustrating the function of the present invention in scavenging oxygen-containing free radicals and harmful gases; Figure 2 This is a schematic diagram of the organic nano-lignin / selenium composite particles of the present invention; Figure 3 This is a schematic diagram of a cigarette filter tip loaded with organic nano-lignin / selenium according to Embodiment 1 of the present invention. Detailed Implementation

[0018] To make the above-mentioned objects, features and advantages of the invention more apparent and understandable, the specific embodiments of the invention are described in detail below.

[0019] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0020] Example 1 (1) Add 100 mL of valerol and 5 g of alkali lignin to a 250 mL beaker, stir until the lignin is completely dissolved, and then add 1 L of deionized water. The system forms a large number of particle suspensions and becomes turbid. Centrifuge and wash three times with deionized water, and vacuum dry to obtain hollow lignin nanospheres with pore throats.

[0021] (2) The prepared porous organic lignin nanoparticles were ultrasonically dispersed in 500 mL of water at a mass concentration of 0.1 wt%, and then an equal mass of 0.02 M sodium selenite solution was added. The mixture was heated and stirred in a water bath at 80 °C for 2 h. The color of the system gradually turned dark red. After the reaction was completed, the mixture was centrifuged and washed three times with deionized water. The mixture was then vacuum dried to obtain organic lignin nanoparticles loaded with nano-selenium.

[0022] (3) Prepare a 5 mg / mL mass concentration suspension of the organic nano-lignin / selenium composite particles obtained in step 2, then immerse the cellulose acetate filter tip in the nano-composite particle suspension for 30 minutes, take it out and freeze dry it further to obtain the loaded nanoporous lignin / selenium high-filtration cigarette filter tip.

[0023] Based on the weight difference before and after, the total content of lignin porous nano / selenium particles was found to be 0.1 wt% of the cellulose acetate content in cigarette filters. Transmission electron microscopy and scanning electron microscopy revealed that the size of the organic lignin nanospheres was between 100-300 nm, the pore throat size was between 10-30 nm, and the size of the loaded selenium nanoparticles was between 1-5 nm. Figure 1 Further energy dispersive spectroscopy results showed that the loaded nano-selenium was equivalent to 5 wt% of lignin mass.

[0024] Cigarettes were prepared by combining a filter tip loaded with nanoporous lignin / selenium nanoparticles with tobacco shreds. Using a regular cellulose acetate filter tip as a control, the draw resistance of the cigarette was measured to be 1.06 kPa and the total particulate matter count was 52 mg, while the gas resistance of the control sample was 1.02 kPa and the total particulate matter count was 54.8 mg. Gas trapping analysis showed that the carbon monoxide content was 2.5 mg and the formaldehyde content was 1.7 mg, while the blank sample showed 7.5 mg of carbon monoxide and 5.7 mg of formaldehyde. Furthermore, compared to the blank sample, the ·O2 content in the gas phase free radicals was measured using a UV spectrophotometer and fluorescence spectrometer. - The contents of ·NO and ·OH decreased by 67%, 79%, and 68%, respectively. These test results indicate that the nanoporous lignin / selenium nanoparticle-loaded filter tip can effectively remove harmful gases from smoke without reducing air resistance or the total number of particulate matter, while also efficiently capturing harmful free radicals in the gas phase.

[0025] Comparative Example 1 (1) Add 100 mL of valerol and 5 g of alkali lignin to a 250 mL beaker, stir until the lignin is completely dissolved, and then add 1 L of deionized water. The system forms a large number of particle suspensions and becomes turbid. Centrifuge and wash three times with deionized water, and vacuum dry to obtain hollow lignin nanospheres with pore throats.

[0026] (2) Prepare the organic nano-lignin particles obtained in step 1 into a suspension with a mass concentration of 5 mg / mL, then immerse the cellulose acetate filter in the nanoparticle suspension for 30 minutes, take it out and freeze-dry it further to obtain the cigarette filter loaded with nanoporous lignin.

[0027] By measuring the weight difference before and after, the total content of lignin porous nanoparticles was found to be 0.1 wt% of the cellulose acetate content in cigarette filters. Transmission electron microscopy and scanning electron microscopy revealed that the size of the organic lignin nanospheres ranged from 100 to 300 nm, and the pore throat size ranged from 10 to 30 nm.

[0028] Cigarettes were prepared by combining a filter tip loaded with nanoporous lignin particles with tobacco shreds. Using a regular cellulose acetate filter tip as a control, the draw resistance of the cigarette was measured to be 1.04 kPa and the total particulate matter count was 53.2 mg, while the gas resistance of the control sample was 1.02 kPa and the total particulate matter count was 54.8 mg. Gas trapping analysis showed that the carbon monoxide content was 3.7 mg and the formaldehyde content was 3.7 mg, while the blank sample showed 7.6 mg of carbon monoxide and 5.6 mg of formaldehyde. Furthermore, compared to the blank sample, the ·O2 content in the gas phase free radicals was measured using a UV spectrophotometer and fluorescence spectrometer. - The contents of ·NO and ·OH decreased by 27%, 29%, and 31%, respectively. These test results indicate that filter tips loaded with nanoporous lignin particles can remove harmful gases and active free radicals from smoke without reducing air resistance or the total number of particulate matter. However, compared to filter tips loaded with nanoporous lignin particles, their filtration efficiency is relatively poor.

[0029] Example 2 (1) Add 100 mL of valerol and 10 g of alkali lignin to a 250 mL beaker, stir until the lignin is completely dissolved, and then add 1 L of deionized water. The system forms a large number of particle suspensions and becomes turbid. Centrifuge and wash three times with deionized water, and vacuum dry to obtain hollow lignin nanospheres with pore throats.

[0030] (2) The prepared porous organic lignin nanoparticles were ultrasonically dispersed in 500 mL of water at a mass concentration of 0.5 wt%, and then an equal mass of 0.04 M sodium selenite solution was added. The mixture was heated and stirred in a water bath at 80 ℃ for 2 h. The color of the system gradually turned dark red. After the reaction was completed, the mixture was centrifuged and washed three times with deionized water. The mixture was then vacuum dried to obtain organic lignin nanoparticles loaded with nano-selenium.

[0031] (3) Prepare a 5 mg / mL mass concentration suspension of the organic nano-lignin / selenium composite particles obtained in step 2, then immerse the cellulose acetate filter tip in the nano-composite particle suspension for 30 minutes, take it out and freeze dry it further to obtain the loaded nanoporous lignin / nano-selenium high-filtration cigarette filter tip.

[0032] By measuring the weight difference before and after loading, the total content of lignin porous nanoparticles was found to be 0.1 wt% of the cellulose acetate content in cigarette filters. Transmission electron microscopy and scanning electron microscopy revealed that the size of the organic lignin nanospheres was between 300-400 nm, the pore throat size was between 10-60 nm, and the size of the loaded selenium nanoparticles was between 10-20 nm. Energy dispersive spectroscopy (EDS) further indicated that the loaded selenium nanoparticles were equivalent to 5 wt% of the lignin mass.

[0033] Cigarettes were prepared by combining a filter tip loaded with nanoporous lignin / selenium nanoparticles with tobacco shreds. Using a regular cellulose acetate filter tip as a control, the draw resistance of the cigarette was measured to be 1.16 kPa and the total particulate matter count was 50.5 mg, while the gas resistance of the control sample was 1.01 kPa and the total particulate matter count was 54.2 mg. Gas trapping analysis showed that the carbon monoxide content was 2.2 mg and the formaldehyde content was 1.5 mg, while the blank sample contained 7.9 mg of carbon monoxide and 5.9 mg of formaldehyde. Furthermore, compared to the blank sample, the ·O2 content in the gas phase free radicals was measured using a combination of UV spectrophotometry and fluorescence spectroscopy. - The contents of ·NO and ·OH decreased by 64%, 81%, and 66%, respectively. These test results indicate that the enlarged pore size of the nanoporous lignin / selenium nanoparticles does not significantly affect the filter's efficient filtration of toxic gases and its ability to capture free radicals.

[0034] Example 3 (1) Add 100 mL of valerol and 7 g of alkali lignin to a 250 mL beaker, stir until the lignin is completely dissolved, and then add 1 L of deionized water. The system forms a large number of particle suspensions and becomes turbid. Centrifuge and wash three times with deionized water, and vacuum dry to obtain hollow lignin nanospheres with pore throats.

[0035] (2) The prepared porous organic lignin nanoparticles were ultrasonically dispersed in 500 mL of water at a mass concentration of 0.5 wt%, and then an equal mass of 0.1 M sodium selenite solution was added. The mixture was heated and stirred in a water bath at 85 ℃ for 3 h. The color of the system gradually turned dark red. After the reaction was completed, the mixture was centrifuged and washed three times with deionized water. The mixture was then vacuum dried to obtain organic lignin nanoparticles loaded with selenium nanoparticles.

[0036] (3) Prepare a 10 mg / mL mass concentration suspension of the organic nano-lignin / selenium composite particles obtained in step 2, then immerse the cellulose acetate filter tip in the nano-composite particle suspension for 30 minutes, take it out and freeze dry it further to obtain the loaded nanoporous lignin / nano-selenium high-filtration cigarette filter tip.

[0037] By measuring the weight difference before and after loading, the total content of lignin porous nanoparticles was found to be 0.25 wt% of the cellulose acetate content in cigarette filters. Transmission electron microscopy and scanning electron microscopy revealed that the size of the organic lignin nanospheres was between 200-300 nm, the pore throat size was between 10-40 nm, and the size of the loaded selenium nanoparticles was between 20-30 nm. Energy dispersive spectroscopy (EDS) further indicated that the loaded selenium nanoparticles were equivalent to 10 wt% of the lignin mass.

[0038] Cigarettes were prepared by combining a filter tip loaded with nanoporous lignin / selenium nanoparticles with tobacco shreds. Using a regular cellulose acetate filter tip as a control, the draw resistance of the cigarette was measured to be 1.06 kPa and the total particulate matter count was 51.5 mg, while the gas resistance of the control sample was 1.01 kPa and the total particulate matter count was 54.2 mg. Gas trapping analysis showed that the carbon monoxide content was 1.2 mg and the formaldehyde content was 1.1 mg, while the blank sample contained 7.7 mg of carbon monoxide and 5.9 mg of formaldehyde. Furthermore, compared to the blank sample, the ·O2 content in the gas phase free radicals was measured using a UV spectrophotometer and fluorescence spectrometer. - The contents of ·NO and ·OH decreased by 84%, 91%, and 86%, respectively. These test results indicate that increasing the content of nano-selenium particles significantly improves the filter's ability to filter toxic gases and capture free radicals.

[0039] Although the present invention has been described in conjunction with the above embodiments, the present invention is not limited to the above embodiments, but only to the appended claims. Those skilled in the art can easily modify and vary it without departing from the essential concept and scope of the present invention.

Claims

1. A method for preparing a high-filtration cigarette filter tip loaded with nanoporous lignin / selenium, characterized in that, Includes the following steps: (1) Dissolve alkali lignin in valerol, the mass of lignin being 1-20 wt% of the mass of valerol, and then add 10-20 times the mass of valerol in deionized water. Centrifuge the resulting suspension and wash it three times with deionized water. Vacuum dry to obtain porous organic lignin nanoparticles. (2) The porous organic lignin nanoparticles prepared in step 1 were ultrasonically dispersed in water at a mass concentration of 0.1-1 wt%, and then an equal mass of 0.01-0.1 M sodium selenite solution was added. The mixture was heated and stirred in a water bath at 80-85 ℃ for 2-3 h. The red suspension was then centrifuged and washed three times with deionized water. The mixture was then vacuum dried to obtain lignin nanoparticles loaded with selenium nanoparticles. (3) Prepare the organic nano-lignin / selenium composite particles obtained in step 2 into a 1-10 mg / mL concentration solution, then immerse the cellulose acetate filter tip in the nano-composite particle suspension for 30-60 min, and then freeze-dry to obtain the loaded nanoporous lignin / selenium high-filtration cigarette filter tip.

2. The preparation method according to claim 1, characterized in that, The porous organic lignin nanoparticles have a size of 100-500 nm and a pore throat size of 10-60 nm, while the selenium nanoparticles have a size of 1-30 nm.

3. The preparation method according to claim 1, characterized in that, The porous lignin nanoparticle content in the filter tip is 0.01-0.5 wt% of the cellulose acetate content, and the nano-selenium particle content is 1-20 wt% of the lignin nanoparticle content.

4. The nanoporous lignin / selenium-loaded high-filtration cigarette filter prepared by any one of claims 1-3 is used to remove O2 from the mainstream cigarette smoke. - It removes NO and OH, as well as carbon monoxide and formaldehyde contained in flue gas.

5. The application of the loaded nanoporous lignin / selenium high-filtration cigarette filter according to any one of claims 1-3 in the preparation of cigarettes and cigarette filters.

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