Green separation method of bamboo parenchyma cells

Abstract

The invention discloses a green separation method of bamboo parenchyma cells, and belongs to the technical field of bamboo processing and utilization. The method comprises the following steps that firstly, bamboo wood is smashed and screened, and bamboo powder is obtained; medium-fine powder and superfine powder in the bamboo powder are directly separated by using an inorganic material rigid plate with a smooth surface; for coarse particle powder in the bamboo powder, water floating separation is firstly carried out by utilizing the density difference of parenchyma cells and bamboo fibers, and then separation is carried out through an inorganic material rigid plate. According to the method, the inorganic material rigid plate is selected, so that the microtopography difference and interfacial acting force (electrostatic adsorption force and Van der Waals force) difference between parenchyma cells in the bamboo powder and other components such as bamboo fibers can be macroscopically reflected as the difference of rolling speed, and the difference is directly converted into an observable separation behavior under macroscopic operation; and the parenchyma cells are effectively separated from the bamboo powder. The method disclosed by the invention is simple in process, low in energy consumption, free of chemical reagents, green and environment-friendly, and has a good industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of bamboo processing and utilization technology, specifically relating to a green method for separating bamboo thin-walled cells. Background Technology

[0002] Bamboo is an important renewable biomass resource, with approximately 7.56 million hectares of bamboo forests in my country. Bamboo is widely used in the papermaking industry due to its short growth cycle (3-4 years), excellent fiber properties, and abundant resources. However, the bamboo pulp papermaking process generates a large amount of processing residues such as bamboo shavings and bamboo powder, which contain numerous bamboo fibers and thin-walled cells. These thin-walled cells have only very thin primary walls and no secondary walls, and are generally spherical or polyhedral in shape with nearly equal diameters.

[0003] Bamboo fiber, with its slender fiber structure and excellent mechanical properties, is an important raw material for the papermaking industry. Bamboo parenchyma cells, on the other hand, possess large cell cavities and a porous structure. Their cell walls are rich in cellulose and hemicellulose and contain numerous hydroxyl functional groups, making them potentially valuable in biomaterials, adsorbents, and functional fillers. However, the mixed distribution of parenchyma cells and fibers in bamboo shavings severely limits the separation, purification, and high-value utilization of parenchyma cells.

[0004] Existing methods for separating thin-walled cells from bamboo mainly include mechanical separation, steam explosion, and chemical treatment. These methods typically suffer from problems such as complex equipment, high energy consumption, or the need for chemical reagents. Furthermore, when relying solely on sieving or water flotation for separation, it is difficult to obtain high-purity thin-walled cells due to the overlap in particle size and density between fibers and thin-walled cells. Therefore, developing a simple, environmentally friendly method for separating high-purity thin-walled cells is of great significance for improving the utilization rate of bamboo shavings and promoting the full-value utilization of bamboo. Summary of the Invention

[0005] To address the problem of obtaining high-purity thin-walled cells from bamboo shavings using existing technologies, this invention provides a green method for separating bamboo thin-walled cells. During the separation process, this invention employs an inclined separation method using a rigid inorganic material plate with a smooth surface, achieving high-purity bamboo thin-walled cell separation. This solves the problems of low efficiency, insufficient purity, and high energy consumption in existing thin-walled cell separation technologies.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A green method for separating bamboo thin-walled cells includes the following steps: (1) Bamboo powder is obtained by crushing and sieving bamboo materials; (2) Bamboo powder is evenly spread on the surface of an inorganic material rigid plate with a smooth surface. By tilting the inorganic material rigid plate or applying vibration to it, the bamboo powder particles roll along the surface of the inorganic material rigid plate under the action of gravity. Based on the morphological differences of different components in bamboo powder and the electrostatic adsorption effect between them and the inorganic material rigid plate, the rolling rate of thin-walled cells is faster than that of other components. (3) Collect the thin-walled cells that roll off the rigid inorganic material plate first, so as to separate the thin-walled cells from the bamboo powder; To improve the purity of thin-walled cells, steps (2) and (3) are repeated 1-5 times; preferably 3 times.

[0007] The reason why the thin-walled cells in bamboo powder can roll off the rigid inorganic material plate at a relatively fast rate in the separation method of this invention is that the thin-walled cells in bamboo powder have a near-spherical or polyhedral structure, which mainly forms point contact with the surface of the rigid inorganic material plate, so the downward rolling rate is fast. Other components in bamboo powder, mainly bamboo fiber, have a slender strip structure, which forms line contact or surface contact with the surface of the rigid inorganic material plate, with a larger contact area. Under the combined action of electrostatic adsorption force and van der Waals force, they are easy to adhere to the surface of the rigid inorganic material plate, and the downward rolling rate is slow. Therefore, based on the difference in the downward rolling speed of thin-walled cells and other components, the thin-walled cells that roll off the rigid inorganic material plate first are collected to achieve rapid separation of thin-walled cells.

[0008] As a preferred technical solution, the inorganic material rigid plate is an inorganic glass plate, ceramic plate or quartz plate. This type of inorganic material rigid plate has high structural rigidity and can have a slight electrostatic interface adsorption effect with bamboo powder, so as to ensure that the contact difference between particles can be effectively amplified, thereby achieving stable separation.

[0009] It should be noted that the inorganic material rigid plate in this application has specific requirements for the material. The electrostatic adsorption between it and the parenchyma cells cannot be too large. Because if the electrostatic adsorption force is too large, the parenchyma cells will be firmly adsorbed on the plate surface and it is difficult to roll off. Therefore, not all material plates are applicable in this invention. For example, when choosing plexiglass, the purpose of this invention cannot be achieved. This is because plexiglass is a typical insulating polymer material with extremely high volume resistivity. When the parenchyma cells rub or come into contact and separate from it, due to the triboelectric effect, electrons or ions will transfer at the interface. Due to the high insulation of plexiglass, the generated static charges cannot be quickly conducted away, and the electrostatic adsorption effect is strong, which easily leads to excessive attachment of parenchyma cell particles, thereby weakening the separation selectivity. Compared with plexiglass, inorganic glass plates, ceramic plates or quartz plates are inorganic substances with lower resistivity. Although they are insulators themselves, in the actual environment, their surfaces are more likely to adsorb moisture in the air (more hydrophilic) than plexiglass and form an extremely thin water film. This water film provides a channel for charge leakage. Because their surface resistivity is relatively low, the static charges generated by contact or friction can leak into the environment relatively quickly and are not likely to form a high-density static charge accumulation on the surface. Therefore, the electrostatic adsorption force on the parenchyma cells is weak, which is beneficial to separation.

[0010] As a preferred technical solution, in order to further improve the separation effect, in step (1), after the bamboo powder is sieved, it is grouped in the order of decreasing particle size to obtain coarse particle powder, medium-fine powder and superfine powder; the mesh number range of the bamboo powder in the coarse particle powder, medium-fine powder and superfine powder is M1 mesh to M2 mesh, M2 mesh to M3 mesh, M3 mesh to M4 mesh in sequence, where: 20 mesh < M1 < M2 < M3 < M4 ≤ 200 mesh; preferably, the difference between adjacent two mesh numbers ≥ 20; the coarse bamboo material samples with a mesh number lower than M1 are continuously pulverized and then sieved again to ensure uniform particle size. Utilize the differences in the content of parenchyma cells and other components such as bamboo fibers in bamboo powder with different particle sizes to achieve the preliminary enrichment of parenchyma cells. Since the content of parenchyma cells in the medium-fine powder and superfine powder is relatively high, they can directly enter the purification step of the inorganic material rigid plate in step (2). However, since the content of parenchyma cells in the coarse particle powder is relatively low, first, due to the density difference between the parenchyma cells and fiber cells, the parenchyma cells are preliminarily separated by water flotation. The upper floating matter obtained by the preliminary water flotation separation is used as the parenchyma cell enrichment. After the parenchyma cell enrichment is dried at 101 ± 2 °C, it is then separated in step (2).

[0011] As a preferred technical solution, the method of the preliminary water flotation separation is: adding the coarse particle powder into water for dispersion and stirring, and then standing for stratification, and collecting the upper floating matter as the parenchyma cell enrichment. Further preferably, the volume ratio of the coarse particle powder to water is 1:(10 - 20).

[0012] As a preferred technical solution, the mesh counts are as follows: 20 mesh ≤ M1 ≤ 40 mesh, 40 mesh ≤ M2 ≤ 80 mesh, 80 mesh ≤ M3 ≤ 140 mesh, and 140 mesh ≤ M4 ≤ 200 mesh. More preferably, the mesh counts corresponding to M1, M2, M3, and M4 are 30 mesh, 60 mesh, 120 mesh, and 200 mesh, respectively. Furthermore, the mesh counts corresponding to M1, M2, M3, and M4 can also be 40 mesh, 80 mesh, 140 mesh, or 200 mesh, etc.

[0013] As a preferred technical solution, the bamboo material is the processing residue or bamboo shavings from the bamboo pulping and papermaking process.

[0014] As a preferred technical solution, the angle of inclination of the inorganic material rigid plate is 10° to 90°, that is, effective separation can be achieved within the range of 10° to 90°. However, if the angle is too large, some fibers may roll off, and if the angle is too small, the separation efficiency will be reduced. Therefore, the preferred angle of inclination of the inorganic material rigid plate is 10° to 90°.

[0015] The present invention has the following beneficial effects: This invention obtains bamboo powder by crushing and sieving bamboo. By selecting a rigid inorganic material plate, the differences in microscopic morphology and interfacial forces (electrostatic adsorption and van der Waals forces) between the thin-walled cells and other components such as bamboo fibers in the bamboo powder can be macroscopically manifested as differences in rolling speed. This directly translates into observable separation behavior under macroscopic operation, effectively achieving the separation of thin-walled cells from bamboo powder. The separation method in this invention is simple to operate, requires no complex chemical reagents or high-energy-consuming machinery, is environmentally friendly, and achieves high separation efficiency of thin-walled cells at low cost, obtaining high-purity thin-walled cells. It is suitable for large-scale application and facilitates the resource utilization of bamboo processing waste. Attached Figure Description

[0016] Figure 1 This is a flowchart of the green separation method for bamboo thin-walled cells according to the present invention; Figure 2 This is a schematic diagram of the separation mechanism of rigid plates made of inorganic materials. Figure 3 A schematic diagram of the water flotation separation process for 30-60 mesh bamboo powder; Figure 4 A schematic diagram showing the process and results of separating 30-60 mesh thin-walled cell concentrates using inorganic glass plates; Figure 5 The results of separating bamboo powder from inorganic glass plates in the 60-120 mesh range are shown; Figure a shows the original sample; Figure b shows the separated thin-walled cells; and Figure c shows the residual fibers on the inorganic glass plate. Figure 6The results of separating bamboo powder from inorganic glass plates in the 120-200 mesh range are shown; Figure a shows the original sample; Figure b shows the separated thin-walled cells; and Figure c shows the residual fibers on the inorganic glass plate. Figure 7 Micrograph of bamboo powder with a mesh size > 200; Figure 8 The image shows the microscopic morphology of bamboo fibers and thin-walled cells separated from 30-60 mesh bamboo powder. Detailed Implementation

[0017] The present invention will be further described below with reference to embodiments, so that those skilled in the art can better understand and implement the present invention, but the embodiments are not intended to limit the present invention. Furthermore, unless otherwise specified, the preparation processes in the following embodiments are conventional methods in the prior art, and therefore will not be described in detail. All raw materials used in the present invention are commercially available products.

[0018] Example A green separation method for bamboo thin-walled cells based on morphological differences and electrostatic adsorption effects, referenced Figure 1 and Figure 2 This includes the following steps: 200 g of bamboo shavings were taken and pulverized using a high-speed pulverizer. The pulverized shavings were then sieved through 30-mesh, 60-mesh, 120-mesh, and 200-mesh sieves to obtain bamboo powder of different particle sizes. Specifically, powders of 30-60 mesh, 60-120 mesh, and 120-200 mesh were defined as coarse powder, medium-fine powder, and ultrafine powder, respectively. Based on particle size differences, the following separation operations were performed on the different powders: For coarse powder particles of 30-60 mesh, since the content of thin-walled cells in the powder is relatively low, the thin-walled cell enrichment is first separated by water flotation, and then purified by inorganic material rigid plate separation. In this embodiment, the inorganic material rigid plate used is an inorganic glass plate. Figure 3 This is a schematic diagram of the water flotation separation process. Take coarse powder of 30-60 mesh (see...). Figure 3 Add 20 times the volume of deionized water (Figure a), stir for 2 minutes, and let stand for 10 minutes (see Figure a). Figure 3 (Figure b). The upper floating matter was collected as a thin-walled cell enrichment (see Figure b). Figure 3 (See Figure c) The lower sediment layer is the fibrous component (see Figure c). Figure 3(See Figure d). The thin-walled cell enrichment was vacuum filtered and dried at 103℃ for 4 h until completely dry. Then, a clean inorganic glass plate was taken, and the thin-walled cell enrichment sample was evenly spread on the plate. By slowly tilting the glass plate (angle 10°-90°) and gently vibrating it (amplitude ≤1 cm), the thin-walled cells rolled off, while the fibers adhered to the glass plate surface, thus achieving separation. Repeating the inorganic glass plate separation operation three times significantly improved the purity of the thin-walled cells. Figure 4 This diagram illustrates the process and results of separating thin-walled cell accumulations using inorganic glass plates. Figure 4 Image a shows a photograph of the thin-walled cell enrichment; image b shows the separation process; image c shows the fibers remaining on the inorganic glass plate; and image d shows the separated thin-walled cells. For medium-fine and ultrafine powders (60-120 mesh, 120-200 mesh), due to their high content of thin-walled cells, water flotation separation is unnecessary; they can be directly purified using inorganic glass plate purification to improve purity. Schematic diagrams of the inorganic glass plate separation results are shown below. Figure 5 and Figure 6 ; For bamboo powder with a mesh size >200, which mainly consists of thin-walled cells, it can be collected directly without repeated purification. Its micrograph is shown below. Figure 7 As shown.

[0019] Figure 8 The images show the microscopic morphology of bamboo fibers and thin-walled cells separated from 30-60 mesh bamboo powder. Images a and b show the microscopic morphology of thin-walled cells, which can be seen to be mostly short-axis, irregular or nearly spherical, with a relatively loose surface structure. Images c and d show the microscopic morphology of bamboo fibers, which can be seen to be typical long spindle shape with sharp ends, dense surface, and a length-to-diameter ratio significantly greater than that of thin-walled cells.

[0020] The results of the analysis of the original purity and the purity after purification by the above separation steps in bamboo powder of different particle sizes are shown in Table 1 below: Table 1

[0021] The results show that the method of the present invention can significantly improve the purity of thin-walled cells. Specifically, the purity of thin-walled cells in 30-60 mesh bamboo powder, after water flotation separation and purification with inorganic glass plates, can reach 99%. For 60-120 mesh and 120-200 mesh bamboo powder, the purity of thin-walled cells after purification can be increased to over 80%.

[0022] In other embodiments, bamboo shavings were used as raw materials, and the operations in Example 1 were repeated. The separation results obtained were similar to those described above, so they will not be repeated here.

[0023] It should be noted that in the above embodiments, the mesh sizes corresponding to M1, M2, M3, and M4 are 30 mesh, 60 mesh, 120 mesh, and 200 mesh, respectively. Besides these values, the mesh sizes corresponding to M1, M2, M3, and M4 can also be set to 40 mesh, 80 mesh, 140 mesh, and 200 mesh. Correspondingly, the mesh sizes of bamboo powder in coarse granular powder, medium-fine powder, and ultrafine powder are 40-80 mesh, 80-140 mesh, and 140-200 mesh, respectively. For those skilled in the art, the specific mesh sizes corresponding to M1, M2, M3, and M4 can be appropriately selected as needed, as long as it satisfies the present invention's purpose of separating bamboo powder into powders with different particle size ranges, such as coarse granular powder, medium-fine powder, and ultrafine powder, to achieve the goal of improving separation effect and efficiency.

[0024] Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A green method for separating bamboo thin-walled cells, characterized in that, It includes the following steps: (1) Pulverize and screen bamboo materials to obtain bamboo powder; (2) Uniformly spread the bamboo powder on the surface of an inorganic material rigid plate with a smooth surface. By tilting the inorganic material rigid plate or applying vibration to it, the bamboo powder particles roll along the surface of the inorganic material rigid plate under the action of gravity; based on the morphological differences of different components in the bamboo powder and the electrostatic adsorption effect between the bamboo powder and the inorganic material rigid plate, the rolling rate of parenchyma cells is faster than that of other components; (3) Collect the parenchyma cells that roll off the inorganic material rigid plate first.

2. The green separation method according to claim 1, characterized in that, The inorganic material rigid plate is an inorganic glass plate, a ceramic plate or a quartz plate.

3. The green separation method according to claim 1, characterized in that, In step (1), after the bamboo powder is screened, it is grouped in the order of decreasing particle size to obtain coarse particle powder, medium-fine powder and ultra-fine powder; the mesh number ranges of the bamboo powder in the coarse particle powder, medium-fine powder and ultra-fine powder are M1 mesh to M2 mesh, M2 mesh to M3 mesh, and M3 mesh to M4 mesh respectively, where: 20 mesh < M1 < M2 < M3 < M4 ≤ 200 mesh; The medium-fine powder and ultra-fine powder are directly subjected to the separation in step (2); The coarse particle powder is first subjected to preliminary separation by water flotation. The upper floating matter obtained by the preliminary water flotation separation is used as a parenchyma cell enrichment material. After the parenchyma cell enrichment material is dried, it is subjected to the separation in step (2).

4. The green separation method according to claim 3, characterized in that, The method of the preliminary water flotation separation is: add the coarse particle powder into water for dispersion stirring and static layering, and collect the upper floating matter as the parenchyma cell enrichment material.

5. The green separation method according to claim 4, characterized in that, The volume ratio of the coarse particle powder to water is 1:(10 - 20).

6. The green separation method according to claim 3, characterized in that, The drying temperature is 101 ± 2°C.

7. The green separation method according to claim 3, characterized in that, The value ranges of M1, M, M3 and M4 are respectively: 30 mesh ≤ M1 ≤ 60 mesh, 60 mesh ≤ M2 ≤ 120 mesh, 120 mesh ≤ M3 ≤ 200 mesh, M4 ≤ 200 mesh.

8. The green separation method according to any one of claims 1 to 6, characterized in that, Steps (2) and (3) are repeated 3 to 5 times.

9. The green separation method according to any one of claims 1 to 6, characterized in that, The bamboo material is the processing residue or bamboo chips in the process of bamboo pulp and paper making.

10. The green separation method according to any one of claims 1 to 6, characterized in that, The tilting angle of the inorganic material rigid plate is 10° to 90°.

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