A green method for extracting biochlorophyll from biomass silkworm excrement by using ionic liquid molecules

Abstract

The application discloses a green method for extracting biological chlorophyll from silkworm excrement by using ionic liquid molecules. The core steps of the method comprise the following steps: firstly, a series of 1-alkyl-3-methyl imidazole bromide ionic liquids with different alkyl chain lengths are synthesized through one-step quaternization reaction; then, the silkworm excrement which is pretreated by drying, crushing and sieving is mixed with the ionic liquid solution according to a specific liquid-solid ratio; the extraction is carried out under the set extraction temperature and time in the dark; finally, the extraction liquid rich in chlorophyll dyes is obtained through solid-liquid separation. Compared with the extraction method using traditional organic solvents such as ethanol and acetone, the ionic liquid used in the application has the advantages of extremely low vapor pressure, low volatility, high safety and recycling, etc. The ionic liquid not only effectively solves the problems of large solvent loss and environmental pollution in the traditional process, but also provides a green and efficient technical scheme for the high-value utilization of the silkworm excrement biomass resource.

Description

Technical Field

[0001] This invention relates to the field of high-value utilization of biomass resources and extraction of natural products, and more specifically to a green method for extracting biological chlorophyll dye from biomass silkworm excrement using ionic liquid molecules. Background Technology

[0002] Silkworm excrement, a major byproduct of sericulture, is produced in large quantities and is rich in various bioactive substances, possessing significant development potential. However, currently, the vast majority of silkworm excrement is discarded indiscriminately or used only as low-value-added products such as feed and fertilizer, resulting in a limited utilization method. Silkworm excrement is rich in chlorophyll derivatives and can serve as a stable source for chlorophyll extraction. However, traditional chlorophyll extraction methods often use organic solvents such as ethanol and acetone, which generally suffer from low extraction efficiency, high solvent consumption, volatility, and difficulty in effective recovery. Furthermore, the use of organic solvents also poses a potential threat to the ecological environment and safe production.

[0003] Therefore, developing a green, efficient, and recyclable bio-chlorophyll extraction technology is of great significance for realizing the high-value utilization of silkworm excrement resources. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a green method for extracting biochlorophyll dyes from biomass silkworm excrement using ionic liquid molecules. Ionic liquids possess excellent solubility, low volatility, and structural designability; by adjusting their alkyl chain length, their polarity and solubility for biomass components can be significantly altered.

[0005] The technical solution adopted by this invention to solve the technical problem is: a green method for extracting biological chlorophyll dye from biomass silkworm excrement using ionic liquid molecules, the method comprising the following steps: S1. Preparation of 1-alkyl-3-methylimidazolium bromide ionic liquid; S2. Crush the dried silkworm excrement and sieve it; S3. The silkworm excrement treated in S2 is mixed with the ionic liquid solution prepared in S1 in a certain proportion, and extracted in the dark at a certain temperature and time to obtain an extract rich in chlorophyll.

[0006] Furthermore, the alkyl group in the 1-alkyl-3-methylimidazolium bromide ionic liquid is any one of ethyl, butyl, hexyl, octyl, or dodecyl.

[0007] Furthermore, the ionic liquid is specifically selected from at least one of 1-ethyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium bromide, 1-hexyl-3-methylimidazolium bromide, 1-octyl-3-methylimidazolium bromide, and 1-dodecyl-3-methylimidazolium bromide.

[0008] Furthermore, in S1, the ionic liquid is obtained by a one-step quaternization reaction of N-methylimidazolium with the corresponding bromoalkane.

[0009] Further, in S3, the mass ratio of silkworm excrement to ionic liquid aqueous solution is 1:5 to 1:20, the temperature is 30 to 85°C, and the time is 30 to 180 min.

[0010] Further, in S3, the ionic liquid solution is an aqueous solution of a 1-alkyl-3-methylimidazolium bromide ionic liquid with a concentration of 0.5~3.0 mol / L.

[0011] Furthermore, the method also includes steps for the recovery and recycling of ionic liquids.

[0012] The beneficial effects of this invention are as follows: This invention provides a green method for extracting biological chlorophyll dyes from biomass silkworm excrement using ionic liquid molecules. Compared with existing technologies, this method significantly improves the extraction efficiency of chlorophyll by using 1-alkyl-3-methylimidazolium bromide ionic liquid as the extraction medium and leveraging the controllability of its alkyl chain length. The extraction yield of medium-carbon chain ionic liquids (such as 1-octyl-3-methylimidazolium bromide) can reach 11.69 mg / g, which is about 40% higher than the traditional ethanol-water extraction method. Simultaneously, the purity of the obtained chlorophyll product is higher, and high-performance liquid chromatography analysis shows that it highly matches the standard and is free from interference from typical carotenoids and other impurities. Furthermore, the extremely low vapor pressure of the ionic liquid avoids the environmental and health risks associated with organic solvent volatilization. The extraction process is green and safe, and the ionic liquid can be efficiently recovered through simple rotary evaporation and drying. The recovered structure remains intact, and the extraction yield does not significantly decrease during recycling, demonstrating good reusability and economic efficiency. More importantly, this invention uses silkworm excrement, a byproduct of sericulture, as raw material, achieving high-value transformation of waste biomass. This not only reduces resource waste and environmental pollution, but also provides a feasible way for the green production of natural chlorophyll dyes, resulting in outstanding ecological and socio-economic benefits. Attached Figure Description

[0013] Figure 1 The image shows the FTIR spectrum of the ionic liquid 1-ethyl-3-methylimidazolium bromide.

[0014] Figure 2 It is the ionic liquid 1-ethyl-3-methylimidazolium bromide 1 H NMR spectrum.

[0015] Figure 3 It is the ionic liquid 1-ethyl-3-methylimidazolium bromide 13 C10 NMR spectrum.

[0016] Figure 4 The MS spectrum of the ionic liquid 1-ethyl-3-methylimidazolium bromide is shown.

[0017] Figure 5 The image shows the FTIR spectrum of the ionic liquid 1-butyl-3-methylimidazolium bromide.

[0018] Figure 6 It is the ionic liquid 1-butyl-3-methylimidazolium bromide 1 H NMR spectrum.

[0019] Figure 7 It is the ionic liquid 1-butyl-3-methylimidazolium bromide 13 C10 NMR spectrum.

[0020] Figure 8 The MS spectrum of the ionic liquid 1-butyl-3-methylimidazolium bromide is shown.

[0021] Figure 9 The image shows the FTIR spectrum of the ionic liquid 1-hexyl-3-methylimidazolium bromide.

[0022] Figure 10 It is the ionic liquid 1-hexyl-3-methylimidazolium bromide. 1 H NMR spectrum.

[0023] Figure 11 It is the ionic liquid 1-hexyl-3-methylimidazolium bromide. 13 C10 NMR spectrum.

[0024] Figure 12 The MS spectrum of the ionic liquid 1-hexyl-3-methylimidazolium bromide is shown.

[0025] Figure 13 The image shows the FTIR spectrum of the ionic liquid 1-octyl-3-methylimidazolium bromide.

[0026] Figure 14 It is the ionic liquid 1-octyl-3-methylimidazolium bromide. 1 H NMR spectrum.

[0027] Figure 15 It is the ionic liquid 1-octyl-3-methylimidazolium bromide. 13 C10 NMR spectrum.

[0028] Figure 16 The MS spectrum of the ionic liquid 1-octyl-3-methylimidazolium bromide is shown.

[0029] Figure 17 The image shows the FTIR spectrum of the ionic liquid 1-dodecyl-3-methylimidazolium bromide.

[0030] Figure 18It is an ionic liquid, 1-dodecyl-3-methylimidazolium bromide. 1 H NMR spectrum.

[0031] Figure 19 It is an ionic liquid, 1-dodecyl-3-methylimidazolium bromide. 13 C10 NMR spectrum.

[0032] Figure 20 The MS spectrum of the ionic liquid 1-dodecyl-3-methylimidazolium bromide is shown.

[0033] Figure 21 HPLC of chlorophyll obtained by different extraction methods.

[0034] Figure 22 FTIR spectrum for the recovery of the ionic liquid 1-octyl-3-methylimidazolium bromide.

[0035] Figure 23 To recover the ionic liquid 1-octyl-3-methylimidazolium bromide 1 H NMR spectrum.

[0036] Figure 24 To recover the ionic liquid 1-octyl-3-methylimidazolium bromide 13 C10 NMR spectrum. Detailed Implementation

[0037] The present invention will be further illustrated below with specific embodiments. However, these examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0038] Example 1 N-methylimidazolium (5.00 g, 60.89 mmol) was dissolved in acetonitrile in a 100 mL round-bottom flask. Bromoethane (6.97 g, 63.94 mmol) was added dropwise. After the addition was complete, the mixture was evacuated to purge with nitrogen, and the mixture was heated to 85 °C and stirred continuously for 1 hour. After the reaction was complete, excess acetonitrile was removed by rotary evaporation. Unreacted reactants were removed by heating and stirring with ethyl acetate. The mixture was washed twice and dried in a 60 °C oven to obtain 1-ethyl-3-methylimidazolium bromide, a white crystalline solid with a melting point of 69–71 °C, in 85.60% yield. FTIR and 1H NMR spectroscopy were used to analyze the product. 1 H NMR, carbon nuclear magnetic resonance (NMR) 13 The structure of 1-ethyl-3-methylimidazolium bromide was characterized by C10 NMR and mass spectrometry (MS). Results are attached. Figure 1 ~Appendix Figure 4 .

[0039] Example 2 N-methylimidazolium (5.00 g, 60.89 mmol) was dissolved in acetonitrile in a 100 mL round-bottom flask. Bromobutane (8.76 g, 63.94 mmol) was added dropwise. After the addition was complete, the mixture was evacuated to purge with nitrogen, and the mixture was heated to 85 °C and stirred continuously for 1.5 hours. After the reaction was complete, excess acetonitrile was removed by rotary evaporation, and unreacted reactants were removed by heating and stirring with ethyl acetate. The mixture was washed twice and dried in a 60 °C oven to obtain 1-butyl-3-methylimidazolium bromide, a white viscous liquid, with a yield of 88.65%. FTIR was used to analyze the product. 1 H NMR, 13 The structure of 1-butyl-3-methylimidazolium bromide was characterized by C10 NMR and MS. Results are attached. Figure 5 ~Appendix Figure 8 .

[0040] Example 3 N-methylimidazolium (5.00 g, 60.89 mmol) was dissolved in acetonitrile in a 100 mL round-bottom flask. Bromohexane (10.55 g, 63.94 mmol) was added dropwise. After the addition was complete, the mixture was evacuated to purge with nitrogen, and the temperature was raised to 85 °C with stirring for 2 hours. After the reaction was complete, excess acetonitrile was removed by rotary evaporation, and unreacted reactants were removed by heating and stirring with ethyl acetate. The mixture was washed twice and dried in a 60 °C oven to obtain 1-hexyl-3-methylimidazolium bromide, a pale yellow viscous liquid, with a yield of 90.18%. FTIR was used to analyze the product. 1 H NMR, 13 The structure of 1-hexyl-3-methylimidazolium bromide was characterized by C10 NMR and MS. Results are attached. Figure 9 ~Appendix Figure 12 .

[0041] Example 4 N-methylimidazole (5.00 g, 60.89 mmol) was dissolved in acetonitrile in a 100 mL round-bottom flask. Bromooctane (12.35 g, 63.94 mmol) was added dropwise. After the addition was complete, the mixture was evacuated to purge with nitrogen, and the temperature was raised to 85 °C with stirring for 1 hour. After the reaction was complete, excess acetonitrile was removed by rotary evaporation. Unreacted reactants were removed by heating and stirring with ethyl acetate. The mixture was washed twice and dried in a 60 °C oven to obtain 1-octyl-3-methylimidazole bromide, an orange-yellow viscous liquid with a yield of 92.85%. FTIR was used to analyze the product. 1 H NMR, 13 The structure of 1-octyl-3-methylimidazolium bromide was characterized by C10 NMR and MS. Results are attached. Figure 13 ~Appendix Figure 16 .

[0042] Example 5 N-methylimidazolium (5.00 g, 60.89 mmol) was dissolved in acetonitrile in a 100 mL round-bottom flask. Bromododecane (15.94 g, 63.94 mmol) was added dropwise. After the addition was complete, the mixture was evacuated to purge with nitrogen, and the temperature was raised to 85 °C with stirring for 3 hours. After the reaction was complete, excess acetonitrile was removed by rotary evaporation, and unreacted reactants were removed by heating and stirring with ethyl acetate. The mixture was washed twice and dried in a 60 °C oven to obtain 1-dodecyl-3-methylimidazolium bromide, a yellow solid with a melting point of 40–42 °C, in a yield of 90.60%. FTIR was used to analyze the product. 1 H NMR, 13 The structure of 1-dodecyl-3-methylimidazolium bromide was characterized by C10 NMR and MS. Results are attached. Figure 17 ~Appendix Figure 20 .

[0043] Examples 6-10 The silkworm excrement was crushed, passed through a 60-mesh sieve, and stored in the dark. 10.0 g of silkworm excrement was weighed into a glass bottle, and 80 g of the ionic liquid obtained in Examples 1-5 was added, followed by 80 g of water. The mixture was sonicated for 60 min, then heated to 60°C and stirred for 60 min. The extract was centrifuged at 10000 r / min for 6 min to obtain the supernatant. Ten times the volume of deionized water was added to the supernatant as a precipitant to precipitate the product. The mixture was centrifuged again, and repeatedly washed with deionized water until the supernatant was colorless. The precipitate was collected and freeze-dried to obtain a green powder, which is chlorophyll. The yields of chlorophyll extracted from silkworm excrement using the ionic liquids in Examples 1-5 were 2.97 mg / g (Example 6), 7.27 mg / g (Example 7), 8.89 mg / g (Example 8), 11.69 mg / g (Example 9), and 2.73 mg / g (Example 10), respectively. The experimental results show that the yield of chlorophyll extracted from biomass silkworm excrement can be effectively controlled by adjusting the alkyl chain length of the ionic liquid.

[0044] Comparative Example 1 (Controlled Experiment) Using ethanol as a control group, the extraction solution was replaced with 80 g ethanol and 80 g water. The experiments in Examples 6-10 were repeated under the same conditions to extract chlorophyll from silkworm excrement, and the chlorophyll extraction yield was 8.32 mg / g. The results show that the chlorophyll content extracted using the medium-carbon-chain ionic liquids 1-hexyl-3-methylimidazolium bromide (Example 8) and 1-octyl-3-methylimidazolium bromide (Example 9) is significantly higher than that extracted using the traditional ethanol extraction method, demonstrating the superiority of the method of this invention.

[0045] Example 11 The standard chlorophyll sample, the chlorophyll extracted with ionic liquid in Example 9, and the chlorophyll extracted with ethanol in Comparative Example 1 were each prepared into solutions with a concentration of 20 μg / mL and characterized by high performance liquid chromatography (HPLC). The test conditions were: C18 column (150 mm × 4.6 mm, 5 μm), column temperature: 30℃; mobile phase: methanol; flow rate: 1.0 mL / min; detection wavelength: 430 nm; injection volume: 10 μL. The results are attached. Figure 21 As shown in the figure. The results indicate that in Example 9, both the product extracted by the ionic liquid and the chlorophyll standard showed chromatographic peaks at 4 min, and the peak shapes were highly consistent. However, the ethanol extract showed a smaller peak at 4 min, and another chromatographic peak appeared at 8 min, presumably a carotenoid. This suggests that the target product obtained through ionic liquid treatment has higher purity and better matches the standard. The ionic liquid method is more suitable than the ethanol method for extracting high-purity chlorophyll from biomass silkworm excrement.

[0046] Example 12 Collect the centrifugal supernatant extracted in Example 9, filter it using a sintered glass funnel to remove small particles, collect the filtrate, remove water by rotary evaporation at 60°C, and then transfer it to an 80°C oven to dry, obtaining the recovered ionic liquid, which is then subjected to FTIR and... 1 H NMR, 13 C10 NMR structural characterization, results are attached. Figure 22 ~Appendix Figure 24 The above characterization indicates that the structure of the ionic liquid was not damaged after recovery. The recovered ionic liquid was then used again for the extraction of chlorophyll from silkworm excrement, with an extraction yield of 11.53 mg / g, which was not significantly lower than that in Example 9. This demonstrates that the ionic liquid of the present invention has good recyclability and reusability in the extraction of chlorophyll from silkworm excrement.

[0047] The above embodiments are only used to illustrate the present invention and are not intended to limit the present invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions also fall within the scope of the present invention, and the patent protection scope of the present invention should be defined by the claims.

Claims

1. A green method for extracting biochlorophyll from biomass silkworm excrement using ionic liquid molecules, characterized in that, The method includes the following steps: S1. Preparation of 1-alkyl-3-methylimidazolium bromide ionic liquid; S2. Crush the dried silkworm excrement and sieve it; S3. The silkworm excrement treated in S2 is mixed with the ionic liquid solution prepared in S1 in a certain proportion, and extracted in the dark at a certain temperature and time to obtain an extract rich in chlorophyll.

2. The green method for extracting biochlorophyll from biomass silkworm excrement using ionic liquid molecules as described in claim 1, characterized in that: The alkyl group in the 1-alkyl-3-methylimidazolium bromide ionic liquid is any one of ethyl, butyl, hexyl, octyl, or dodecyl.

3. The green method for extracting biochlorophyll from biomass silkworm excrement using ionic liquid molecules as described in claim 1, characterized in that: The ionic liquid is specifically selected from at least one of 1-ethyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium bromide, 1-hexyl-3-methylimidazolium bromide, 1-octyl-3-methylimidazolium bromide, and 1-dodecyl-3-methylimidazolium bromide.

4. The green method for extracting biochlorophyll from biomass silkworm excrement using ionic liquid molecules as described in claim 1, characterized in that: In S1, the ionic liquid is obtained by a one-step quaternization reaction of N-methylimidazolium with the corresponding bromoalkane.

5. The green method for extracting biochlorophyll from biomass silkworm excrement using ionic liquid molecules as described in claim 1, characterized in that: In S3, the mass ratio of silkworm excrement to ionic liquid aqueous solution is 1:5 to 1:20, the temperature is 30 to 85°C, and the time is 30 to 180 min.

6. The green method for extracting biochlorophyll from biomass silkworm excrement using ionic liquid molecules as described in claim 1, characterized in that: In S3, the ionic liquid solution is an aqueous solution of a 1-alkyl-3-methylimidazolium bromide ionic liquid with a concentration of 0.5~3.0 mol / L.

7. The green method for extracting biochlorophyll from biomass silkworm excrement using ionic liquid molecules as described in claim 1, characterized in that: The method also includes steps for the recovery and recycling of ionic liquids.

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