Method for extracting chlorophyll from waste vegetable leaves

Abstract

The invention discloses a method for extracting chlorophyll from waste vegetable leaves, and belongs to the technical field of chlorophyll extraction, and the method comprises the following steps: S1, collecting the waste vegetable leaves, removing impurities in the waste vegetable leaves, and chopping the waste vegetable leaves, S2, putting the chopped waste vegetable leaves into a squeezer for squeezing, S3, conveying a mixed solution generated after squeezing to a stacked screw machine, and carrying out centrifugal separation on the mixed solution to obtain the chlorophyll. The mixed liquid is subjected to solid-liquid separation through gravity and extrusion by a stacked screw machine to obtain relatively pure chlorophyll liquid, S4, the chlorophyll liquid treated by the stacked screw machine and solid residues are input into a high-pressure filter pressing device, so that the chlorophyll liquid is purer, and S5, the liquid treated by the high-pressure filter pressing device is subjected to chlorophyll extraction by adopting a proper organic solution, so that the chlorophyll is obtained. Through the combination of the squeezer, the stacked screw machine and the high-pressure filter pressing device, automatic and continuous production can be realized, a large amount of waste vegetable leaves can be quickly treated, the production efficiency is greatly improved, and the requirements of industrial large-scale production are met.

Description

[0001] The present invention relates to the technical field of chlorophyll extraction, and more specifically, to a method for extracting chlorophyll using waste vegetable leaves. Background Art

[0002] Chlorophyll is a class of green pigments contained in higher plants and other organisms capable of photosynthesis. Its molecular structure consists of a porphyrin ring formed by four pyrrole rings, a magnesium atom, cyclopentanone, phytol, etc. Chlorophyll absorbs most of the red and violet light but reflects green light, so it appears green. Waste vegetable leaves contain chlorophyll. By extracting chlorophyll using waste vegetable leaves, the pressure of garbage disposal can be reduced, resource recycling can be promoted, new economic growth points can be created, and the environmental protection awareness of citizens can also be enhanced.

[0003] In the prior art, manual grinding or simple soaking is mostly used. After manually crushing the waste vegetable leaves, they are soaked and extracted with a solvent. The operation is cumbersome, time-consuming, and the processing volume is extremely small, making it difficult to meet the requirements of large-scale production. In addition, the solid-liquid separation is not thorough. For some methods that only perform preliminary filtration, there is a large interference of impurities in the subsequent extraction and distillation processes, resulting in a low purity of the obtained chlorophyll product. Summary of the Invention

[0004] The present invention mainly provides a method for extracting chlorophyll using waste vegetable leaves, which can solve the problems of low extraction efficiency, poor product purity, solvent residue and pollution proposed in the above background art.

[0005] To achieve the above object, the present invention provides the following technical solution: A method for extracting chlorophyll using waste vegetable leaves, comprising the following steps: First, collect waste vegetable leaves, remove the soil and small gravel impurities therein by washing, then cut them, and then put the cut waste vegetable leaves into a pressing machine for extrusion to make the juice in the waste vegetable leaves flow out. Transport the produced mixed liquid to a spiral press. The spiral press further separates the liquid and solid residue by gravity and extrusion to obtain a relatively pure chlorophyll liquid. At the same time, treat the sewage generated by the processing of the pressing machine and the spiral press. Then, input the solid residue separated by the spiral press and the obtained relatively pure chlorophyll liquid into a high-pressure filter device for further purification. Finally, use a suitable organic solution to extract chlorophyll from the liquid treated by the high-pressure filter device, and then distill the extract.

[0006] Furthermore, the pressure of the pressing roller of the pressing machine is 0.5 - 1 MPa at the beginning, and then gradually increases to 2 - 5 MPa, and the rotation speed of the pressing roller is 10 - 30 revolutions per minute.

[0007] Furthermore, the rotation speed of the spiral press is 2 - 5 revolutions per minute, the gap between the back pressure plates is 0.5 - 2 mm, and the dosage of the flocculant is 0.1% - 0.5% of the mass of the mixed liquid produced by the extrusion of the pressing machine.

[0008] Furthermore, the pressure of the high-pressure filter press device is 0.5 - 2.0 MPa, the filtration time is 20 - 60 minutes, and the pore size of the filter cloth is 10 - 50 microns.

[0009] Furthermore, the sewage treatment generated during the processing of the press and the screw press includes: pretreatment, biological treatment, advanced treatment, disinfection and discharge or reuse;

[0010] Pretreatment, through the physical interception of the grille, removes larger suspended impurities in the sewage, and at the same time introduces the sewage treated by the grille into the regulation tank;

[0011] Biological treatment, sends the sewage after the regulation tank into the anaerobic reactor, and sends the sewage treated anaerobically into the aerobic treatment unit;

[0012] Advanced treatment, adds a coagulant to the sewage treated biologically to precipitate the dirt in the sewage, and passes the supernatant after precipitation through sand filtration and activated carbon filtration;

[0013] Disinfection and discharge or reuse, disinfects the water after advanced treatment during discharge to make it meet the discharge standards.

[0014] Furthermore, the chlorophyll extraction solution is ethanol, and the ethanol concentration is 50% - 95%, the ratio of material to liquid is 1:10 - 1:20, the temperature during extraction is 40°C - 80°C, the extraction time is 1 - 4 hours, and the final stirring speed is 100 - 300 revolutions per minute.

[0015] Furthermore, since the extraction agent during extraction is ethanol and the boiling point of ethanol is 78.3°C, the distillation temperature is 80°C - 85°C, and the cooling water temperature is 15°C - 25°C.

[0016] The beneficial effects of a method for extracting chlorophyll from waste vegetable leaves according to the present invention are as follows:

[0017] Through the combination of a press, a screw press, and a high-pressure filter press device, automated and continuous production can be achieved, a large amount of waste vegetable leaves can be quickly processed, the production efficiency is greatly improved, meeting the requirements of large-scale industrial production. At the same time, through multiple solid-liquid separation steps, impurities are gradually removed, from the preliminary separation by the press, further solid-liquid separation by the screw press to the deep purification by the high-pressure filter press device, effectively reducing the interference of impurities on chlorophyll extraction, and a high-purity chlorophyll product can be obtained. In addition, the sewage generated during the production process is systematically treated, including links such as pretreatment, biological treatment, advanced treatment, and disinfection and discharge or reuse, reducing environmental pollution and making the entire production process more green and sustainable. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be further described in detail below with reference to the drawings and specific implementation methods.

[0019] Figure 1 This is a schematic flow chart of a method for extracting chlorophyll from waste vegetable leaves according to the present invention. Detailed implementation manners

[0020] To make the technical solution of the present invention clearer, the following further describes the present invention in detail with reference to the accompanying drawings and specific embodiments.

[0021] Embodiment 1

[0022] As Figure 1 shown, according to one aspect of the present invention, a technical solution is provided: a method for extracting chlorophyll from waste vegetable leaves, including the following steps: First, collect waste vegetable leaves, remove the soil and small gravel impurities therein through cleaning, then cut them into pieces, and then put the cut waste vegetable leaves into a pressing machine for extrusion to make the juice in the waste vegetable leaves flow out. Transport the mixed liquid generated by extrusion to a spiral press filter. The spiral press filter further separates the liquid and solid residue through gravity and extrusion to obtain a relatively pure chlorophyll liquid. At the same time, treat the sewage generated by the processing of the pressing machine and the spiral press filter. Then, input the solid residue (sludge) separated by the spiral press filter and the obtained relatively pure chlorophyll liquid into a high-pressure filter press device for further purification. Finally, use a suitable organic solution to extract chlorophyll from the liquid processed by the high-pressure filter press device, and then distill the extract.

[0023] At the beginning, the pressure of the pressing roller of the pressing machine is 0.5 - 1 MPa, and then it gradually increases to 2 - 5 MPa, and the rotation speed of the pressing roller is 10 - 30 revolutions per minute;

[0024] Among them, at the beginning, the pressure of the pressing roller is set at 0.5 - 1 MPa (belonging to a relatively low pressure). This pressure can make the cut waste vegetable leaves smoothly enter the pressing process, avoid impacting the components of the pressing machine due to excessive initial pressure, and protect the equipment; at the same time, prevent the waste vegetable leaves from being over-extruded when they just come into contact with the pressing roller, which may cause blockage of the feeding port or uneven pressing, and ensure the smoothness of the subsequent process. Subsequently, the pressure is gradually increased to 2 - 5 MPa because as the pressing progresses, the juice in the waste vegetable leaves is continuously squeezed out, its structure is gradually damaged, and its pressure-bearing capacity is enhanced. A higher pressure can further squeeze out the remaining juice, improve the juice extraction rate, obtain more chlorophyll-containing liquid, and provide sufficient raw materials for the subsequent extraction steps;

[0025] The rotational speed of the pressing roller is set at 10 - 30 revolutions per minute (belonging to a relatively low rotational speed range). At this rotational speed, the waste vegetable leaves have a relatively sufficient residence time between the pressing rollers and can be fully squeezed, enabling the juice to flow out as much as possible, thus improving the pressing efficiency and quality. If the rotational speed is too fast, the waste vegetable leaves may be discharged before being fully pressed, reducing the juice extraction rate. Moreover, the relatively low rotational speed can reduce the friction and impact force between the pressing roller and the waste vegetable leaves as well as other components of the equipment, reduce equipment wear, extend the service life of the equipment, and at the same time reduce the equipment maintenance cost and failure risk.

[0026] The rotational speed of the spiral press is 2 - 5 revolutions per minute, the gap of the back pressure plate is 0.5 - 2 mm, and the dosage of the flocculant is 0.1% - 0.5% of the mass of the mixed liquid generated by the extrusion of the press.

[0027] The rotational speed of the spiral press is set at 2 - 5 revolutions per minute because too slow a rotational speed will result in low treatment efficiency and inability to separate the solid and liquid in the mixed liquid in time, leading to insufficient equipment throughput; while too fast a rotational speed may cause the residence time of the sludge in the spiral press to be too short, without sufficient time for dehydration, affecting the separation effect, and at the same time may cause greater wear to the equipment and increase energy consumption.

[0028] The back pressure plate with a gap of 0.5 - 2 mm effectively avoids too large a gap, which makes it easy for the sludge to be extruded from the gap during the extrusion process, unable to form effective extrusion dehydration, resulting in a relatively high solid content in the separated water and poor solid - liquid separation effect; too small a gap, although it can enhance the extrusion effect, will increase the load on the equipment, may cause equipment failure, and at the same time will make it difficult for the solid particles in the sludge to be discharged, affecting the throughput.

[0029] Finally, the dosage of the flocculant is set at 0.1% - 0.5% because too little dosage of the flocculant cannot cause the fine particles in the mixed liquid to flocculate into larger flocs sufficiently, which is not conducive to solid - liquid separation, and will make the separated water turbid and the solid recovery rate low; too much dosage will not only increase the cost, but also may make the flocs too large, causing blockage in the spiral press, affecting the normal operation of the equipment, and at the same time may cause too high a water content in the separated solid cake.

[0030] The pressure of the high - pressure filter press device is 0.5 - 2.0 MPa, the filtration time is 20 - 60 minutes, and the pore size of the filter cloth is 10 - 50 microns.

[0031] Among them, a pressure of 0.5 - 2.0 MPa is to avoid too low pressure, which cannot effectively squeeze the liquid and solid residue (sludge) through the filter cloth, resulting in slow filtration speed, poor solid-liquid separation effect, and high moisture content of the filter cake. While too high pressure, although it can improve the filtration speed and solid-liquid separation effect, may cause greater damage to the filter cloth, shorten the service life of the filter cloth, and also increase the energy consumption and operating cost of the equipment. Even it may exceed the bearing limit of the equipment and cause safety problems;

[0032] And a filtration time of 20 - 60 minutes can avoid the situation that solid particles and solid residue (sludge) in the liquid are not fully intercepted on the filter cloth, resulting in turbid filtrate, nor will it reduce the production efficiency and increase the operating time and energy consumption of the equipment;

[0033] Finally, a filter cloth pore size of 10 - 50 microns effectively avoids the situation that too large pore size cannot effectively intercept fine solid particles, which will make the filtrate contain more solid impurities and affect the filtration quality. While too small pore size, although it can improve the filtration accuracy, will increase the filtration resistance, reduce the filtration speed, and easily cause the filter cloth to be blocked, requiring frequent cleaning or replacement of the filter cloth.

[0034] The sewage treatment generated during the processing of the press and the spiral press includes: pretreatment, biological treatment, advanced treatment, disinfection and discharge or reuse;

[0035] Pretreatment, through the physical interception of the grid, removes larger suspended impurities in the sewage (such as vegetable leaf fragments, fibers, etc.), prevents these large particle substances from blocking the subsequent treatment equipment, and at the same time introduces the sewage treated by the grid into the regulation tank to play a buffering role, balancing the water quality and water volume of the sewage, and avoiding the influence on the treatment effect due to excessive fluctuations in water quality and water volume during the subsequent treatment process;

[0036] Biological treatment, sends the sewage after the regulation tank into an anaerobic reactor (such as an anaerobic digestion tank). Under anaerobic conditions, anaerobic microorganisms decompose the organic pollutants in the sewage, converting macromolecular organic substances into small molecular organic substances and gases such as methane. Anaerobic treatment can effectively reduce most of the chemical oxygen demand (COD) in the sewage, reduce the subsequent treatment load, and send the sewage treated by anaerobic treatment into an aerobic treatment unit (such as the aeration tank of the activated sludge method). Under sufficient oxygen supply, aerobic microorganisms further decompose the remaining organic pollutants in the sewage, converting them into inorganic substances such as carbon dioxide and water. At the same time, through the metabolism of microorganisms, the removal of nutrients such as nitrogen and phosphorus is realized;

[0037] Advanced treatment: Coagulants (such as polyaluminum chloride, etc.) are added to the biologically treated sewage. Through coagulation, the tiny colloidal particles and suspended impurities in the sewage are aggregated into larger flocs, causing the dirt in the sewage to precipitate, further removing the suspended solids and some dissolved pollutants in the water. The supernatant after precipitation is filtered through sand and activated carbon, which can effectively remove the remaining fine particles and some organic pollutants, pigments, etc., improving the water quality. Among them, activated carbon also has an adsorption effect, which can adsorb and remove the odors and some refractory organic substances in the water;

[0038] Disinfection, discharge or reuse: The water after advanced treatment is disinfected during discharge to kill pathogenic microorganisms such as bacteria and viruses in the water, making it meet the discharge standards, and used for links with low water quality requirements (such as factory area greening irrigation, road flushing, etc.) to achieve the recycling of water resources.

[0039] The chlorophyll extraction solution is ethanol, and the ethanol concentration is 50%-95% (for example, if the concentration is too low, the polarity of ethanol is relatively strong, which may lead to poor extraction effect and inability to effectively extract the target components, because the solubility of some non-polar or weakly polar components in low-concentration ethanol is low, while if the concentration is too high, such as using anhydrous ethanol, the solubility of some components with larger polarity may be reduced. At the same time, high-concentration ethanol has a higher cost and is flammable, posing certain safety risks). While ensuring the extraction effect, taking into account cost and safety, it has good solubility for most components in waste vegetable leaves. The material-liquid ratio is 1:10 - 1:20 (for example, if the material-liquid ratio is too small, that is, the amount of solvent used is relatively small and cannot fully contact the components in the waste vegetable leaves, resulting in incomplete extraction and low extraction rate of the target components. If the material-liquid ratio is too large, although the extraction effect can be improved, it will increase the amount of solvent used and the cost of subsequent separation and purification, and may also introduce more impurities). While better extracting the target components, controlling the solvent usage and cost, the extraction temperature is 40°C - 80°C (for example, if the temperature is too low, the molecular movement is slow, the diffusion rate of the solute in the solvent is slow, and the extraction efficiency is low, requiring a longer extraction time to achieve a better effect. If the temperature is too high, on the one hand, ethanol may volatilize too fast, resulting in solvent loss and affecting the extraction effect; on the other hand, it may destroy some thermosensitive components, and at the same time increase energy consumption and equipment requirements). While improving the extraction efficiency, reducing the destruction of components and the volatilization of the solvent, and the extraction time is 1 - 4 hours (for example, if the extraction time is too short, the solute has not been fully transferred from the waste vegetable leaves to the ethanol solvent, resulting in incomplete extraction and low extraction rate. If the extraction time is too long, it will not only increase energy consumption and production costs, but also may cause some side reactions to occur, or the components that have been extracted may degrade, etc., which is not conducive to the extraction effect). To make the extraction reach a better balance and obtain a higher extraction rate, finally the stirring speed is 100 - 300 revolutions per minute (for example, if the stirring speed is too slow, the waste vegetable leaves and the ethanol solvent cannot be fully mixed, resulting in poor mass transfer effect and affecting the extraction efficiency. If the stirring speed is too fast, the waste vegetable leaves may be broken excessively, resulting in too many impurities entering the extraction liquid, and at the same time increasing the wear and energy consumption of the equipment). It can ensure good mass transfer effect, improve the extraction efficiency, and reduce the introduction of impurities.

[0040] Since the extractant used in extraction is ethanol and the boiling point of ethanol is 78.3°C, the distillation temperature is 80°C - 85°C (if the temperature is too low, ethanol cannot be fully vaporized, the distillation speed is slow, the efficiency is low, and ethanol cannot be effectively separated. If the temperature is too high, on the one hand, ethanol vaporization will be too violent, which may lead to unstable distillation process and even flooding phenomenon; on the other hand, too high temperature may cause a large amount of other components in the extract to vaporize and mix into the ethanol vapor, affecting the purity of ethanol and may also damage some heat-sensitive components). Among them, the cooling water temperature is 15°C - 25°C (if the cooling water temperature is too low, the cooling effect will be too strong, which may cause the distilled ethanol vapor to quickly condense into liquid in the condenser and flow back to the distillation flask, affecting the distillation efficiency; at the same time, too low water temperature may cause dew condensation or even icing on the surface of the equipment, damaging the equipment. If the cooling water temperature is too high, the cooling effect is not good, the ethanol vapor cannot be fully condensed, and part of the ethanol will be discharged with the tail gas, resulting in losses, reducing the recovery rate of ethanol, and may also affect subsequent collection and storage).

[0041] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the present invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A method for extracting chlorophyll from waste vegetable leaves, characterized in that, It includes the following steps: First, collect waste vegetable leaves, remove the soil and small gravel impurities by washing, then cut them into pieces, and then put the chopped waste vegetable leaves into a press for extrusion to make the juice in the waste vegetable leaves flow out. Transport the mixed liquid produced by extrusion to a spiral press. The spiral press further separates the liquid and solid residue through gravity and extrusion to obtain a relatively pure chlorophyll liquid. At the same time, treat the sewage generated during the processing of the press and the spiral press. After that, input the solid residue separated by the spiral press and the relatively pure chlorophyll liquid obtained into a high-pressure filter device for further purification. Finally, use a suitable organic solution to extract chlorophyll from the liquid processed by the high-pressure filter device, and then distill the extract.

2. The method for extracting chlorophyll from waste vegetable leaves according to claim 1, characterized in that: At the beginning, the pressure of the pressing roller of the press is 0.5 - 1 MPa, and then it gradually increases to 2 - 5 MPa, and the rotation speed of the pressing roller is 10 - 30 revolutions per minute.

3. The method for extracting chlorophyll from waste vegetable leaves according to claim 1, characterized in that: The rotation speed of the spiral press is 2 - 5 revolutions per minute, the gap between the back pressure plates is 0.5 - 2 mm, and the dosage of the flocculant is 0.1% - 0.5% of the mass of the mixed liquid produced by the extrusion of the press.

4. A method for extracting chlorophyll from waste vegetable leaves according to claim 1, characterized in that: The pressure of the high-pressure filter device is 0.5 - 2.0 MPa, the filtration time is 20 - 60 minutes, and the pore size of the filter cloth is 10 - 50 microns.

5. A method for extracting chlorophyll from waste vegetable leaves according to claim 1, characterized in that: The treatment of the sewage generated during the processing of the press and the spiral press includes: pretreatment, biological treatment, advanced treatment, disinfection and discharge or reuse; Pretreatment: Through the physical interception of the grid, remove the larger suspended impurities in the sewage, and at the same time introduce the sewage treated by the grid into the regulation tank; Biological treatment: Send the sewage after the regulation tank into an anaerobic reactor, and then send the sewage treated anaerobically into an aerobic treatment unit; Advanced treatment: Add a coagulant to the sewage treated biologically to precipitate the dirt in the sewage, and pass the supernatant after precipitation through sand filtration and activated carbon filtration; Disinfection and discharge or reuse: Disinfect the water after advanced treatment during discharge to make it meet the discharge standard.

6. A method for extracting chlorophyll from waste vegetable leaves according to claim 1, characterized in that: The chlorophyll extraction solution is ethanol, and the ethanol concentration is 50% - 95%, the ratio of material to liquid is 1:10 - 1:20, the temperature during extraction is 40℃ - 80℃, the extraction time is 1 - 4 hours, and the final stirring speed is 100 - 300 revolutions per minute.

7. A method for extracting chlorophyll from waste vegetable leaves according to claim 6, characterized in that: Because the extraction agent during extraction is ethanol and the boiling point of ethanol is 78.3℃, the distillation temperature is 80℃ - 85℃, and the cooling water temperature is 15℃ - 25℃.

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