A method for preparing high purity nicotine using waste tobacco

Abstract

The application discloses a method for preparing high-purity nicotine by using waste tobacco, and the preparation process is as follows: waste tobacco is subjected to drying and crushing treatment, and then is added with dilute acid solution A for heating extraction, and a filtrate is obtained through coarse filtration; the filtrate is subjected to membrane filtration treatment to obtain nicotine salt concentrated solution; the pH value of the nicotine salt concentrated solution is adjusted to 11-13 by using alkali solution A, and the nicotine salt concentrated solution is subjected to reduced pressure distillation, and the distillate is absorbed by using dilute acid solution B, and then is subjected to membrane molecular interception treatment to obtain nicotine salt with a purity of 35%-45%; then, the pH value is adjusted to 11-13 by adding alkali solution B, and then organic solvent is added for extraction, and the organic solvent extraction liquid is collected; the organic solvent extraction liquid is subjected to reduced pressure distillation by using a rectifying column system, and the organic solvent and nicotine are collected respectively, so that high-purity nicotine with a purity of more than 99% is obtained. The method effectively solves the problems of excessive use of organic solvent in the nicotine extraction process of waste tobacco, environmental pollution, large energy consumption in the production process, many impurities, complex production process and the like, reduces the production cost, and is suitable for large-scale production.

Description

Technical Field

[0001] This invention relates to the field of tobacco waste recycling, specifically a method for preparing high-purity nicotine from waste tobacco. Background Technology

[0002] my country is a major tobacco producer, consumer, and grower, ranking first in the world in both planting area and output. However, due to limitations in planting, management, and processing techniques, approximately 25% of tobacco leaves and by-products are wasted during cultivation, transportation, and cigarette production. Consequently, a large amount of waste tobacco leaves, stems, dust, and stalks are generated annually across the country. In the past, waste tobacco leaves and stems were mostly disposed of through burning and landfilling, which easily leads to water pollution and soil hardening in tobacco fields, causing environmental pollution, reduced soil fertility, and decreased income for tobacco farmers. Therefore, how to fully develop the potential value of these waste tobacco products and transform them into valuable resources has become an urgent problem for tobacco processing enterprises and tobacco farmers.

[0003] Currently, over 3,000 compounds have been identified in tobacco, among which important compounds such as solanesol, nicotine, tobacco protein, and tobacco pectin have wide applications in chemical, pharmaceutical, and agricultural fields. If these substances can be extracted and utilized, turning waste tobacco leaves into raw materials for production, environmental pollution can be reduced, aligning with the concept of green development. Tobacco contains various alkaloids, with over 40 identified, among which nicotine is the most abundant, accounting for approximately 95% of the total alkaloids in tobacco. Nicotine, also known as tobacco alkaloid, is a widely used alkaloid. Nicotine can produce certain physiological stimuli in humans, thus causing addiction, which is the main factor giving tobacco its commercial value. In addition, nicotine is also widely used in fine chemicals, pharmaceuticals, organic synthesis, defense industries, and agriculture. Small amounts of nicotine can stimulate the central nervous system, having a calming and antidepressant effect, and relieving tension. In medicine, it can be used to develop drugs for treating cardiovascular diseases, skin conditions, snake venom, insect bites, and unidentified swellings. Citric acid nicotine, derived from nicotine, is also a major component in the production of high-grade cigarette quality improvers. Nicotine with a content of 40% can be used to formulate highly effective, residue-free, and pollution-free pesticides and biological pesticides specifically for the production of grains, oilseeds, vegetables, and fruits. In recent years, with the rapid expansion of nicotine product applications, the market demand for natural nicotine has been increasing. Extracting nicotine and other substances from waste tobacco to obtain natural chemical raw materials that meet green and hygienic standards not only has high economic value and brings new opportunities to enterprises, but also contributes to building a resource-saving and environmentally friendly society.

[0004] In recent years, the utilization of waste tobacco has mainly included direct fermentation to produce organic fertilizer; and the extraction of high-value-added deep-processed products such as nicotine and solanesol, with the remaining residue used as raw material for organic fertilizer production. Currently, nicotine production commonly employs organic solvent extraction. The extensive use of solvents not only causes pollution but also results in low yields and relatively low product purity. Patent CN111170989A uses a membrane for positive pressure osmosis concentration, primarily to remove water from the steam distillation nicotine system; the membrane here only serves a concentration function. Moreover, the final product is only 40%-60% nicotine sulfate, with low purity. Patent CN112384504A uses direct thermal concentration of the obtained nicotine sulfate, which suffers from excessive energy consumption; furthermore, the purity of nicotine obtained through this method is generally low, only greater than 90%, failing to meet the current market demand for high-purity nicotine (>99%). The invention patent with publication number CN114605382A uses alkalization to treat nicotine sulfate, followed by direct extraction with an organic solvent to extract nicotine. During the alkalization extraction process, a large amount of water-soluble impurities, such as organic acids, tannins, water-soluble polysaccharides, and proteins, are also extracted. Many of these substances contain salts that act as emulsifiers, altering the hydrophilic-lipophilic balance (HLB) value of the extraction equilibrium system, resulting in unclear phase separation interfaces, severe emulsification, and difficulty in organic solvent extraction. Simultaneously, some of these substances are transferred to the organic solvent during extraction, increasing impurities and reducing nicotine purity. Furthermore, this process still uses thermal concentration during nicotine production, leading to excessive energy consumption. Although the invention patent with publication number CN104725351A does not use organic solvents, its evaporation concentration and alcohol precipitation processes involve significant thermal evaporation of water, resulting in very high energy consumption and further increasing production costs. Moreover, the widespread use of high-pressure steam also poses certain operational hazards.

[0005] In summary, existing nicotine preparation methods suffer from problems such as low nicotine purity, high energy consumption, high cost, complex production processes, and high operational risks. Summary of the Invention

[0006] This invention provides a method for preparing high-purity nicotine from waste tobacco. This method effectively solves the problems of excessive organic solvent usage, high energy consumption, low purity due to many impurities, and complex production process when extracting nicotine from waste tobacco. It effectively reduces production costs and is suitable for large-scale production.

[0007] To achieve the above objectives, the specific solution adopted by the present invention is as follows:

[0008] A method for preparing high-purity nicotine from waste tobacco mainly includes the following steps:

[0009] Step 1: Dry and pulverize the waste tobacco, then add dilute acid solution A for heating and extraction, and coarsely filter the collected final extract to obtain a transparent and clear filtrate.

[0010] Step 2: The filtrate is subjected to membrane filtration to remove large molecular weight polysaccharides and proteins, as well as small molecular weight water molecules and small organic molecules, to obtain nicotine salt concentrate.

[0011] Step 3: Adjust the pH of the nicotine salt concentrate to 11-13 with alkaline solution A to obtain a free nicotine solution; then distill the free nicotine solution under reduced pressure, absorb the distillate with dilute acid solution B until the pH of the absorption system is ≤5, and then perform membrane retention treatment to remove water and some small molecule impurities to obtain nicotine salt with a purity of 35%-45%.

[0012] Step 4: Add alkaline solution B to the obtained nicotine salt to adjust the pH value of the nicotine salt to 11-13, then add organic solvent for extraction, and collect the organic solvent extract.

[0013] Step 5: The organic solvent extract is subjected to vacuum distillation using a distillation column system. The organic solvent and nicotine are collected separately. The nicotine obtained is high-purity nicotine with a purity greater than 99%.

[0014] Furthermore, in step one, the particle size of the pulverized waste tobacco is 10-20 mesh.

[0015] Furthermore, in step one, the dilute acid solution A used is dilute hydrochloric acid or dilute sulfuric acid, and the pH value of dilute acid solution A is 2-4.

[0016] Further, in step one, the specific parameters of the extraction process are as follows: the volume ratio of dilute acid solution A to waste tobacco is 1:(6-8), the extraction temperature is 60-80ºC, the extraction time is 2-4 hours, the extraction is performed 2-3 times, and the extracts obtained from each extraction are combined to obtain the final extract.

[0017] Furthermore, in step one, the extract is coarsely filtered using a plate and frame filter press combined with a microfiltration membrane to obtain a transparent and clear filtrate.

[0018] Furthermore, in step two, when using membrane filtration, microfiltration, ultrafiltration, nanofiltration, or reverse osmosis membranes are selected, and the water molecules that are removed can be reused as a solvent for dilute acid solution A.

[0019] Furthermore, in step three, the alkaline solution A used is any one or more of KOH, NaOH, CaO, Ca(OH)2, ammonia, and Na2CO3.

[0020] The dilute acid solution B used is either dilute hydrochloric acid or dilute sulfuric acid, and the pH value of dilute acid solution B is 1-3.

[0021] Furthermore, in step four, the alkaline solution B used is any one or more of KOH, NaOH, CaO, Ca(OH)2, ammonia, and Na2CO3.

[0022] Furthermore, in step four, the organic solvent used is one or more of n-hexane, ethyl acetate, chloroform, and petroleum ether;

[0023] The volume of the organic solvent is 1 / 3 to 1 / 2 of the volume of the solution to be extracted, and the extraction is performed 2 to 3 times.

[0024] Furthermore, in step five, the organic solvent extract is subjected to vacuum distillation using a distillation column system. The organic solvent is collected at 40-60ºC, and nicotine is collected at 150-160ºC. The collected organic solvent can be reused in the extraction process after being recovered by distillation.

[0025] Beneficial effects:

[0026] 1) Significantly reduced use of organic solvents: Throughout the entire production process, organic solvents are only used in the final refining stage. This not only greatly reduces the amount of organic solvents used, but also allows for their recovery through vacuum distillation, achieving a recovery rate of over 90%, essentially realizing zero emissions of organic solvents.

[0027] The use of membranes significantly reduces energy consumption throughout the production process: By replacing traditional heating evaporation and water removal with membrane filtration concentration technology, and by removing large molecular impurities such as proteoglycans through membrane molecule retention, energy consumption throughout the production process is greatly reduced. For a production unit with an annual output of 100 tons of nicotine, more than 15 million yuan in energy consumption expenditure can be saved annually; this also meets the national requirements for green and low-carbon production.

[0028] The production process is simpler: the application of membrane molecular retention replaces the ethanol precipitation method in the acid extraction of nicotine to remove large molecules such as proteins and polysaccharides. It effectively removes large molecules such as proteins and polysaccharides generated during nicotine extraction, as well as water and other small organic molecules in the system, making subsequent operations more convenient and simplifying the production process.

[0029] This invention effectively solves the emulsification problem in the acid extraction and organic solvent extraction process: When acid extraction is followed by direct extraction with an extractant, severe emulsification occurs. This invention removes polysaccharides and proteins through membrane molecule retention, followed by alkaline distillation and acid absorption, effectively removing most of the emulsifying impurities. Therefore, no emulsification occurs during subsequent organic solvent extraction.

[0030] The production process generates almost no waste: As can be seen from the production flow, the tobacco residue after nicotine extraction can be used as raw material for bio-organic fertilizer; the water generated during molecular retention can be used as an extraction solvent for nicotine extraction from the raw material; the removal of polysaccharides and proteins by membrane molecular retention can be processed into animal feed; and the organic solvent used for extraction can be recovered through distillation and reused as a solvent for further extraction. Therefore, the entire production process can achieve almost zero emissions, meeting national environmental protection requirements. Attached Figure Description

[0031] Figure 1 This is a process flow diagram for preparing high-purity nicotine in Example 1. Detailed Implementation

[0032] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0033] This invention provides a method for preparing high-purity nicotine from waste tobacco raw materials. The waste tobacco raw materials include tobacco stalks and waste tobacco leaves generated during tobacco harvesting, as well as tobacco residues and fragments generated during re-drying, cigarette manufacturing, packaging, and transportation, which cannot be used as raw materials for cigarette production. The preparation process of high-purity nicotine includes the following steps:

[0034] Step 1: Dry and pulverize the waste tobacco. The particle size of the pulverized waste tobacco is 10-20 mesh. Then, add dilute acid solution A for heating and extraction. The volume ratio of dilute acid solution A to waste tobacco (referred to as liquid-to-material ratio) is 1:(6-8). The extraction temperature is 60-80ºC, the extraction time is 2-4 hours, and the extraction is repeated 2-3 times. Combine the extracts obtained from each extraction to obtain the final extract. Then, use a conventional plate and frame filter press combined with a microfiltration membrane to coarsely filter the final extract to obtain a transparent and clear filtrate.

[0035] Step 2: Perform membrane filtration on the filtrate to remove substances with larger molecular weights such as polysaccharides and proteins, as well as substances with smaller molecular weights such as water molecules and small organic molecules, to obtain nicotine salt concentrate; wherein, the membrane can be microfiltration, ultrafiltration, nanofiltration or reverse osmosis membrane, etc., and the device can be hollow fiber, spiral wound, plate and frame filter press or tubular, etc.

[0036] Step 3: Adjust the pH of the nicotine salt concentrate to 11-13 with alkaline solution A to obtain a free nicotine solution. Then, distill the free nicotine solution under reduced pressure and absorb the distillate with dilute acid solution B until the pH of the absorption system is ≤5. Then, perform membrane retention treatment to obtain nicotine salt with a purity of 35%-45%.

[0037] Step 4: Add alkaline solution B to the obtained nicotine salt to adjust the pH of the nicotine salt to 11-13, then add an organic solvent for extraction and collect the organic solvent extract; the organic solvent used is one or more of non-polar or weakly polar organic solvents such as n-hexane, ethyl acetate, chloroform, and petroleum ether; the volume of the organic solvent is 1 / 3-1 / 2 of the volume of the solution to be extracted, and the extraction is performed 2-3 times;

[0038] Step 5: The organic solvent extract is subjected to vacuum distillation using a distillation column system. The organic solvent is collected at 40-60ºC, and the nicotine is collected at 150-160ºC. The nicotine obtained is high-purity nicotine with a purity greater than 99%.

[0039] In step one, the dilute acid solution A is an inorganic acid such as dilute hydrochloric acid or dilute sulfuric acid, and the pH value of the extract is between 2 and 4.

[0040] In step three, the alkaline solution A used is any one or more of KOH, NaOH, CaO, Ca(OH)2, ammonia, and Na2CO3; the dilute acid solution B used is an inorganic acid such as dilute hydrochloric acid or dilute sulfuric acid, and the pH value of the dilute acid solution B is 1-3.

[0041] In step four, the alkaline solution B used is any one or more of KOH, NaOH, CaO, Ca(OH)2, ammonia, and Na2CO3.

[0042] Preferably, the entire preparation process also includes a reuse process. For example, the tobacco residue after nicotine extraction can be used as a raw material for bio-organic fertilizer; the water generated during the molecular retention process can be used as a solvent for dilute acid solution A to extract nicotine from the raw material; and the organic solvent used for extraction can be recovered by distillation and then used as a solvent for extraction.

[0043] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0044] Example 1

[0045] A method for preparing high-purity nicotine using waste tobacco, please refer to [reference needed]. Figure 1 The main steps include the following:

[0046] Step 1: After the waste tobacco raw material is dried, it is crushed to 10 mesh, and then a dilute sulfuric acid aqueous solution with a pH of 2 and a liquid-to-material ratio of 6 is added. The mixture is heated to 60ºC and extracted for 4 hours. The extraction is repeated twice. The extracts are combined and coarsely filtered using a plate and frame filter press and a microfiltration membrane to obtain a clear filtrate.

[0047] Step 2: The filtrate is subjected to ultrafiltration to remove large molecules such as polysaccharides and proteins, and then nanofiltration is used to remove water and small organic molecules to obtain nicotine salt concentrate.

[0048] Step 3: Adjust the pH of the nicotine salt concentrate to 11 with dilute sodium hydroxide to obtain a free nicotine solution. Then, distill the free nicotine solution under reduced pressure and absorb the distillate with dilute sulfuric acid solution at pH=1 until the pH of the absorption system is 5. Then, concentrate the absorption solution using a nanofiltration membrane to obtain nicotine salt with a purity of 40% (i.e., nicotine sulfate).

[0049] Step 4: Add sodium hydroxide solution to the obtained nicotine sulfate to adjust the pH to 13, then add n-hexane (1 / 3 volume of the mixture) for extraction. Repeat the extraction 3 times and combine the extracts.

[0050] Step 5: Add the extract to a distillation vessel and distill under reduced pressure. Collect n-hexane at a pressure of 5000 Pa and a temperature of 40-60ºC, and collect nicotine at a pressure of 2000 Pa and a temperature of 150-160ºC to obtain high-purity nicotine with a purity of 99.1%.

[0051] Using a 100-liter pilot plant and following the production process of Example 1, the total cost of producing 10 kg of nicotine is approximately 500 yuan, which translates to a cost of 500,000 yuan per ton, indicating low production costs.

[0052] Example 2

[0053] A method for preparing high-purity nicotine from waste tobacco mainly includes the following steps:

[0054] Step 1: After the waste tobacco raw material is dried, it is crushed to 20 mesh, and then an aqueous solution of olefinic sulfuric acid with a pH of 4 is added at a liquid-to-material ratio of 8. The mixture is heated to 80ºC and extracted for 2 hours. The extraction is repeated 3 times. The extracts are combined and coarsely filtered using a plate and frame filter press and a microfiltration membrane to obtain a clear filtrate.

[0055] Step 2: Ultrafiltration of the filtrate removes large molecules such as polysaccharides and proteins, followed by nanofiltration to remove water and small organic molecules, yielding a concentrated nicotine salt solution.

[0056] Step 3: Adjust the pH of the nicotine salt concentrate to 11 with dilute sodium hydroxide solution to obtain a free nicotine solution. Then, distill the free nicotine solution under reduced pressure and absorb the distillate with dilute sulfuric acid solution at pH=3 until the pH of the absorption system reaches 5. Then, concentrate the absorption solution using a nanofiltration membrane to obtain nicotine salt with a purity of 40% (i.e., nicotine sulfate).

[0057] Step 4: Add sodium hydroxide solution to the obtained nicotine sulfate to adjust the pH to 11, then add petroleum ether accounting for 1 / 2 volume of the mixture for extraction. Repeat the extraction twice and combine the extracts.

[0058] Step 5: Add the extract to a distillation vessel and distill under reduced pressure. Collect n-hexane at a pressure of 5000 Pa and a temperature of 40-60ºC, and collect nicotine at a pressure of 2000 Pa and a temperature of 150-160ºC to obtain high-purity nicotine with a purity greater than 99.3%.

[0059] Using a 100-liter pilot plant and following the production process of Example 2, the total cost of producing 10 kg of nicotine is approximately RMB 560, which translates to a cost of RMB 560,000 per ton, indicating low production costs.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention in any way. All equivalent transformations or modifications made in accordance with the essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for preparing high-purity nicotine from waste tobacco, characterized in that, Includes the following steps: Step 1: Dry and pulverize the waste tobacco, then add dilute acid solution A for heating and extraction, and coarsely filter the collected final extract to obtain a transparent and clear filtrate. Step 2: The filtrate is subjected to membrane filtration. Ultrafiltration removes polysaccharides and proteins with larger molecular weights, while nanofiltration removes water molecules and small organic molecules with smaller molecular weights, to obtain nicotine salt concentrate. Step 3: Adjust the pH of the nicotine salt concentrate to 11-13 with alkaline solution A to obtain a free nicotine solution; then distill the free nicotine solution under reduced pressure, absorb the distillate with dilute acid solution B until the pH of the absorption system is ≤5, and then perform nanofiltration membrane retention treatment to obtain nicotine salt with a purity of 35%-45%. Step 4: Add alkaline solution B to the obtained nicotine salt to adjust the pH value of the nicotine salt to 11-13, then add organic solvent for extraction, and collect the organic solvent extract. Step 5: The organic solvent extract is subjected to vacuum distillation using a distillation column system. The organic solvent and nicotine are collected separately. The nicotine obtained is high-purity nicotine with a purity greater than 99%. In step one, the dilute acid solution A used is dilute hydrochloric acid or dilute sulfuric acid, and the pH value of dilute acid solution A is 2-4. In step one, the specific parameters of the extraction process are as follows: extraction temperature is 60-80℃, extraction time is 2-4 hours, extraction is performed 2-3 times, and the extracts obtained from each extraction are combined to obtain the final extract. In step one, the extract is coarsely filtered using a plate and frame filter press combined with a microfiltration membrane to obtain a clear and transparent filtrate. In step three, the dilute acid solution B used is dilute hydrochloric acid or dilute sulfuric acid, and the pH value of dilute acid solution B is 1-3; In step five, the organic solvent extract is subjected to vacuum distillation using a distillation column system. The organic solvent is collected at 40-60℃, and nicotine is collected at 150-160℃. The collected organic solvent is recovered by distillation and reused in the extraction process.

2. The method for preparing high-purity nicotine from waste tobacco according to claim 1, characterized in that: In step one, the particle size of the crushed waste tobacco is 10-20 mesh.

3. The method for preparing high-purity nicotine from waste tobacco according to claim 1, characterized in that: In step two, the water molecules removed by the membrane are reused as a solvent for dilute acid solution A.

4. The method for preparing high-purity nicotine from waste tobacco according to claim 1, characterized in that: In step three, the alkaline solution A used is any one or more of KOH, NaOH, Ca(OH)2, ammonia, or Na2CO3 solution.

5. The method for preparing high-purity nicotine from waste tobacco according to claim 1, characterized in that: In step four, the alkaline solution B used is any one or more of KOH, NaOH, Ca(OH)2, ammonia, or Na2CO3 solution.

6. The method for preparing high-purity nicotine from waste tobacco according to claim 1, characterized in that: In step four, the organic solvent used is one or more of n-hexane, ethyl acetate, chloroform, and petroleum ether; The volume of the organic solvent is 1 / 3 to 1 / 2 of the volume of the solution to be extracted, and the extraction is performed 2 to 3 times.

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