A lignin micro-nanoparticle preparation device based on microflow atomization

Abstract

The utility model belongs to the field of biomass material processing, for a kind of lignin micro-nano particle preparation device based on micro-flow atomization technology, it include: reaction kettle and install the pneumatic atomization spray head in reaction kettle top, the high-speed stirring paddle is installed in the bottom of reaction kettle, the bottom edge in reaction kettle is equipped with pH sensor;Reaction kettle side is equipped with feed inlet, feed inlet and metering feed pump one are connected by pipeline one, and the bottom of reaction kettle is equipped with discharge outlet with side wall junction;Pneumatic atomization spray head is connected with high-pressure gas transmission pump by pipeline two, and pneumatic atomization spray head is connected with metering feed pump two by pipeline three;Pneumatic atomization spray head, metering feed pump one, metering feed pump two, high-speed stirring paddle, pH sensor, high-pressure gas transmission pump are electrically connected with electric control system module.The technology can achieve lignin dissolution, atomization and particle forming continuous operation, and the obtained micro-nano particle has good monodispersity, high surface activity, low color and other characteristics, which provides an efficient preparation means for the development of bio-based functional materials.

Description

Technical Field

[0001] This utility model relates to the field of fine processing of lignin, specifically a device for preparing lignin micro-nano particles based on microfluidic atomization. Background Technology

[0002] Lignin, as the second most abundant renewable aromatic polymer in nature, shows great potential for application in the field of micro and nanomaterials. Its micro- and nano-particle processing is an important way to realize the high-value utilization of lignin, and it has significant application value in drug carriers, functional coatings, and composite reinforcing materials.

[0003] Current research largely focuses on the application and process exploration of lignin micro / nanoparticles. For example, in a study titled "Green Preparation of Lignin Nanoparticles and Their Application in Active Packaging," researchers used a "lignin-first" strategy to conduct delignification studies using oxygen-enhanced ethanol under mild conditions. The results showed that under the process conditions of 80% ethanol concentration, 90℃ temperature, and a liquid-to-solid ratio of 25:1, the lignin yield from powdered wheat straw could reach 52.3%, which is 65.0% higher than that of rod-shaped raw materials under the same conditions. Studies on lignin structure and carbohydrate composition indicated that, with minimal changes in carbohydrate composition (≤1%) and lignin structure (mainly β-O-4 units), oxygen could induce a significant amount of lignin dissolution. Based on the molecular weight and polydispersity of lignin, dissolved oxygen could be uniformly transferred in a mild organic solvent system, thereby promoting lignin degradation. For example, in the study entitled "Microfluidic Preparation and Application of Lignin / Chitosan Nanoparticles", the researchers investigated: (1) Microfluidic synthesis of lignin / chitosan nanoparticles for pH-responsive delivery of anticancer drugs: Lignin / chitosan nanoparticles with controlled structures were synthesized in a simple and scalable microfluidic system. The Lig / ChiNPs had spherical morphology and nanoscale size (~180nm), with a surface charge of +54.5mV. The benzene ring structure of lignin endowed it with the potential to load hydrophobic drugs; (2) Lignin / chitosan nanoparticle-stabilized Pickering emulsions for enzyme immobilization and catalysis: The Lig / ChiNPs nanoparticle dispersion prepared using a microfluidic system was directly used as a stabilizing particle (water contact angle of 89.7°) to successfully prepare an oil-in-water Pickering emulsion. By changing the oil-to-water ratio, it was found that the droplet size of the emulsion increased at RO / Wlt; 7:3, and it showed good thermal stability, salt resistance, storage stability and pH-responsive reversible cycling. However, existing lignin micro- and nano-particle preparation technologies generally suffer from bottlenecks such as poor monodispersity, wide particle size distribution, and insufficient process controllability.

[0004] Traditional precipitation methods use the principle of solvent exchange, adding anti-solvent lignin-breaking agents and mechanical stirring to achieve lignin precipitation, but have the following inherent defects: (1) uneven mixing of the solution leads to significant differences in the hydrogen bonding between molecules, which easily causes disordered aggregation; (2) lack of real-time control of dynamic changes in pH value, and extreme pH causes secondary agglomeration of particles; (3) intermittent operation mode leads to batch-to-batch quality fluctuations.

[0005] Microfluidic atomization technology, driven by a high-pressure air pump, disperses lignin solutions into micron-sized droplets with controllable particle size. This significantly increases the droplet specific surface area, accelerates the diffusion and exchange rate between the antisolvent (e.g., acidic aqueous solution) and the solvent (e.g., eutectic solvent), and shortens the precipitation time. The microfluidic droplets are diffusely distributed within the antisolvent, avoiding the differences in intermolecular hydrogen bonding caused by local concentration gradients in traditional processes. This significantly reduces the disordered aggregation of lignin molecules due to uneven collision probabilities.

[0006] To address the aforementioned technical challenges, there is an urgent need to develop novel preparation devices, focusing on solving the following key technical problems: (1) achieving controllable generation of micron-sized uniform droplets; (2) establishing an antisolvent supply system that dynamically responds to pH changes; and (3) constructing a continuous production process. By innovatively designing the synergistic mechanism of microfluidic atomization and intelligent regulation, the technical barrier to controlling the monodispersity of lignin nanoparticles can be overcome, thus promoting the industrial application of bio-based nanomaterials. Utility Model Content

[0007] The purpose of this invention is to provide a device for preparing lignin micro / nanoparticles based on microfluidic atomization. A metering pump is activated based on real-time feedback from a pH sensor to regulate the pH of the antisolvent in the reactor. A pneumatic atomizing nozzle atomizes the lignin solution via a high-pressure air pump and the metering pump. A stirrer in the reactor agitates the antisolvent, providing shear force. The atomized lignin solution contacts the stirred antisolvent and precipitates as lignin micro / nanoparticles, which are then redispersed under shear force. The resulting lignin dispersion is then discharged and collected through the bottom outlet. This solves the problems mentioned in the background art.

[0008] The technical solution adopted in this utility model is as follows:

[0009] A device for preparing lignin micro / nanoparticles based on microfluidic atomization, the device comprising: a reaction vessel 1 and a pneumatic atomizing nozzle 2 installed on the top of the reaction vessel; a high-speed stirring paddle 3 installed at the bottom of the reaction vessel 1; a pH sensor 4 installed at the bottom edge of the reaction vessel 1; a feed inlet 5 installed on the side of the reaction vessel 1, the feed inlet 5 being connected to a metering pump 6 via a pipe 11; and a discharge outlet 7 installed at the junction of the bottom and side wall of the reaction vessel 1; the pneumatic atomizing nozzle 2 being connected to a high-pressure air pump 8 via a pipe 12; and the pneumatic atomizing nozzle 2 being connected to a metering pump 9 via a pipe 13; the pneumatic atomizing nozzle 2, the metering pump 6, the metering pump 9, the high-speed stirring paddle 3, the pH sensor 4, and the high-pressure air pump 8 are all electrically connected to an electrical control system module 10.

[0010] As a further limitation of the above scheme, the volume of the reactor 1 is 80-120L.

[0011] As a further limitation of the above scheme, the height of the pneumatic atomizing nozzle 2 at the top of the reactor 1 is adjustable, with an adjustment range of 1-30 cm in the vertical direction.

[0012] As a further limitation of the above scheme, the pneumatic atomizing nozzle 2 is provided with a plurality of circular holes, and the angle between the perpendicular line of the plane containing the circular holes and the direction of the vertical axis of the pneumatic atomizing nozzle 2 is 15-45°.

[0013] As a further limitation of the above scheme, the high-speed stirring paddle 3 has a rotation speed of 0-600 rpm.

[0014] As a further limitation of the above scheme, the blade length of the high-speed stirring paddle 3 is 5-10cm.

[0015] As a further limitation of the above scheme, the high-speed stirring paddle 3 is located at the bottom center of the reaction vessel 1.

[0016] As a further limitation of the above scheme, the feed inlet 5 is located at two-thirds of the height of the side of the reactor 1.

[0017] As a further limitation of the above scheme, the diameters of pipe 11, pipe 2, and pipe 3 are all 2-5mm.

[0018] As a further limitation of the above scheme, the flow rate of both the metering pump 6 and the metering pump 9 is 1-500 ml / min.

[0019] As a further limitation of the above scheme, the working air pressure of the high-pressure gas pump 8 is 0-40MPa.

[0020] As a further limitation of the above scheme, the material of the reactor 1 is acid-resistant tetrafluoroethylene, or the reactor 1 is composed of a metal body and an acid-resistant and corrosion-resistant coating on the inner wall.

[0021] Compared with the prior art, the beneficial effects of this utility model are:

[0022] The lignin micro / nanoparticle preparation device based on microfluidic atomization provided by this invention creatively disperses the lignin solution into tiny micron-sized droplets through a pneumatic atomizer, greatly increasing the specific surface area of ​​the lignin solution and effectively shortening the contact time between the lignin solution and the antisolvent. Through the connection and setting of the electronic control system module, metering pump, pH sensor, and display device, the entire device can achieve real-time linkage feedback and dynamically adjust the pH value of the antisolvent within the target range, overcoming the problems of manual intermittent measurement and feedback of pH control lag or unevenness in traditional preparation processes. Compared with the traditional solvent exchange method, the technical solution of this invention can significantly reduce the particle size distribution range. In addition, the stirrer designed in this invention generates a controllable shear rate field in the reaction vessel, and performs in-situ exfoliation of newly formed particles through turbulent vortex action. This design can effectively reduce the secondary agglomeration of lignin micro / nanoparticles. The integrated structure realizes continuous operation of solution atomization, pH control, shear dispersion and product collection, and the single batch processing time is significantly shortened compared with the intermittent process, and the solvent consumption is significantly reduced. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure and connection of the lignin micro / nanoparticle preparation device based on microfluidic atomization provided by this utility model.

[0024] Figure 2 This is a schematic diagram of the pneumatic atomizing nozzle in the microfluidic atomization-based lignin micro / nanoparticle preparation device provided by this utility model.

[0025] 1-Reaction vessel; 2-Pneumatic atomizing nozzle; 3-High-speed stirring paddle; 4-pH sensor; 5-Inlet; 6-Metering pump one; 7-Outlet; 8-High-pressure air pump; 9-Metering pump two; 10-Electrical control system module; 11-Pipe one; 12-Pipe two; 13-Pipe three. Detailed Implementation

[0026] Refer to the attached diagram in the instruction manual. Figure 1-2This utility model provides a device for preparing lignin micro / nanoparticles based on microfluidic atomization. The device specifically includes: a reaction vessel 1 and a height-adjustable pneumatic atomizing nozzle 2 installed on the top of the reaction vessel. A high-speed stirring paddle 3 is installed at the center of the bottom of the reaction vessel 1, and a pH sensor 4 is installed at the bottom edge of the reaction vessel 1. The pH sensor is connected to an electronic control system module 10 (an external integrated control device), and the pH of the antisolvent is displayed in real time on the electronic control system module 10. A feed inlet 5 is installed at two-thirds of the height of the side of the reaction vessel 1, and the feed inlet 5 is connected to a metering pump 6 through a pipe 11. A discharge outlet 7 is installed at the junction of the bottom and side wall of the reaction vessel 1. The pneumatic atomizing nozzle 2 is connected to a high-pressure gas pump 8 through a pipe 12 and to a metering pump 9 through a pipe 13.

[0027] As a further limitation of the above scheme, the material of the reactor 1 is acid-resistant tetrafluoroethylene, or the reactor 1 is a metal vessel with an acid-resistant tetrafluoroethylene layer on its inner wall, or the reactor 1 is a metal vessel with other acid-resistant and corrosion-resistant coatings on its inner wall, such as polysiloxane anti-corrosion and acid-resistant coating material. The purpose of limiting the materials to these is to reduce the acid corrosion of the reactor by the acidic material during the lignin separation reaction, avoid the generation of other pollutants in the reaction material, and extend the lifespan of the reactor 1.

[0028] As a further limitation of the above scheme, the volume of the reactor 1 is 80-120L. More specifically, the volume can preferably be 80L, 90L, 100L, 110L, or 120L. By limiting and optimizing the volume of the reactor 1, it can be adapted to the needs of various production environments and production scales, thereby improving the applicability of the equipment.

[0029] As a further limitation of the above scheme, the vertical height of the pneumatic atomizing nozzle 2 at the top of the reactor 1 is adjustable, with a vertical adjustment range of 0-30 cm. More specifically, the adjustment is achieved using an electric vertical lifting device, with the pneumatic atomizing nozzle 2 located at the lower end of the lifting device. The height adjustment range is preferably 0 cm, 10 cm, 20 cm, or 30 cm. By limiting and optimizing the height of the pneumatic atomizing nozzle 2, the nozzle can always be at the optimal liquid level, allowing the lignin solution to be fully dispersed and atomized, further improving production stability.

[0030] As a further refinement of the above scheme, the pneumatic atomizing nozzle 2 is provided with several circular holes, which are evenly distributed around the conical outer surface of the atomizing nozzle. The angle between the perpendicular line of the plane containing the circular holes and the vertical axis of the pneumatic atomizing nozzle 2 is 15-45°. More specifically, the spray angle range can be 15°, 20°, 25°, 30°, 35°, 40°, 45°, etc., and can be adjusted by changing the atomizing nozzle with different settings. By limiting and optimizing the spray angle of the atomizing nozzle 2, it can be ensured that the lignin solution will not be sprayed onto the reactor wall and re-aggregate to form droplets during the dispersion process, thus ensuring the quality stability of the lignin micro-nano particles.

[0031] As a further limitation of the above scheme, the high-speed stirring paddle 3 rotates at a speed of 0-600 rpm. More specifically, the stirring paddle 3 can preferably be in the range of 0 rpm, 150 rpm, 300 rpm, 450 rpm, 600 rpm, etc. By limiting and optimizing the rotation speed, the degree of stirring of the antisolvent can be adjusted, thereby controlling the shear force in the antisolvent, which helps to further disperse lignin micro- and nano-particles. The turbulent vortex action allows for in-situ exfoliation of newly formed particles, and this design can effectively reduce the secondary agglomeration of lignin micro- and nano-particles.

[0032] As a further limitation of the above scheme, the length of the high-speed stirring paddle 3 blades is 5-10 cm. More specifically, the preferred length range of the stirring paddle 3 blades is 5 cm, 7 cm, 10 cm, etc. By limiting and optimizing the length of the stirring paddle 3 blades, the equipment can achieve sufficient stirring effect under solvent-resistant conditions of different volumes, ensuring the stability and size uniformity of the produced lignin nanoparticles.

[0033] As a further definition of the above scheme, the operation of the electronic control system module 10 includes regulating the rotation speed of the pneumatic atomizing nozzle 2, metering pump 6, metering pump 9, and high-speed agitator 3, as well as the opening and closing of the high-pressure gas pump 8, based on the feedback signal from the pH sensor, and displaying the real-time pH value of the antisolvent in the reactor. More specifically, the pneumatic atomizing nozzle 2, metering pump 6, metering pump 9, and high-speed agitator 3 are electrically connected to the electronic control system module 10. Upon receiving feedback signals from changes in the pH signal displayed on the electronic control system module 10, the module automatically sends signals to the metering pump 6, etc., to control the addition of different liquids to adjust the pH within an appropriate range.

[0034] As a further limitation of the above scheme, the diameters of the pipe 11 connecting the feed inlet 5 to the metering pump 6, the pipe 12 connecting the pneumatic atomizing nozzle 2 to the high-pressure air pump 8, and the pipe 13 connecting the pneumatic atomizing nozzle 2 to the metering pump 9 are 2-5 mm. Specifically, the feed inlet 5 is directly connected to the metering pump 6 via a pipe, and the pneumatic atomizing nozzle 2 is fixedly connected to the high-pressure air pump 8 and the metering pump 9 via a separate pipeline, and atomization is achieved at the spray nozzle through a gas-liquid mixing structure.

[0035] As a further limitation of the above scheme, the flow rates of metering pump 6 and metering pump 9 are 1-500 ml / min. Specifically, metering pump 6 is connected to inlet 5 via pipe 11 for real-time delivery of pH adjuster, and metering pump 9 is connected to pneumatic atomizing nozzle 2 via pipe 13 for delivery of lignin solution. This flow rate range covers the needs from micro-volume addition (e.g., 1 mL / min) to batch delivery (e.g., 500 mL / min), and is suitable for various scenarios in laboratories and industrial production.

[0036] As a further limitation of the above scheme, the high-pressure air pump 8 operates at a pressure of 0-40 MPa. Specifically, the high-pressure air pump 8 is connected to the pneumatic atomizing nozzle 2 via pipe 12 to pressurize the lignin solution and promote its atomization into micro / nano droplets. This pressure range effectively adapts to different lignin solution flow rates, avoiding poor atomization effects due to insufficient pressure.

[0037] The lignin micro / nanoparticle preparation device based on microfluidic atomization provided by this utility model operates as follows: An appropriate amount of antisolvent is placed in the reaction vessel 1. The pneumatic atomizing nozzle 2, metering pump 6, metering pump 9, high-speed stirring paddle 3, pH sensor 4, etc., are electrically connected to the electronic control system module 10. The pH sensor 4 sends real-time pH information to the electronic control system module 10, and the electronic control system module 10 displays the pH change information on the display screen. At the same time, the electronic control system module 10 automatically sends a feeding signal to metering pump 6 and / or metering pump 9 according to the adjustment signal given by the pH change, so as to automatically turn on / off or adjust the size of the two metering pumps to adjust the addition of liquid and adjust the pH in the reaction vessel to an appropriate range. The pneumatic atomizing nozzle 2, high-pressure air pump 8, and metering pump 9 are all connected and fixed via pipelines. Atomization is achieved at the spray nozzle through a gas-liquid mixing structure. Metering pump 9 is used to transport the lignin solution, and high-pressure air pump 8 provides pressure for solution atomization. The pneumatic atomizing nozzle 2 adjusts its height according to the antisolvent level. A high-speed stirring paddle 3 is activated during atomization, providing shear force to the antisolvent and performing in-situ exfoliation of newly formed particles through turbulent vortex action. This design effectively reduces secondary agglomeration of lignin micro / nano particles. After the reaction, the lignin micro / nano particle suspension can be discharged through outlet 7. The integrated structure proposed in this invention enables continuous operation of solution atomization, pH control, shear dispersion, and product collection. The single-batch processing time is significantly shortened compared to intermittent processes, and solvent consumption is significantly reduced.

[0038] The embodiments described above only illustrate some implementation methods of this utility model, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of this utility model patent. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model.

Claims

1. A device for preparing lignin micro / nanoparticles based on microfluidic atomization, characterized in that, The device includes: a reactor (1) and a pneumatic atomizing nozzle (2) installed on the top of the reactor. A high-speed stirring paddle (3) is installed at the bottom of the reactor (1), and a pH sensor (4) is installed at the bottom edge of the reactor (1). A feed inlet (5) is installed on the side of the reactor (1), and the feed inlet (5) is connected to a metering pump (6) through a pipe (11). A discharge outlet (7) is installed at the junction of the bottom and the side wall of the reactor (1). The pneumatic atomizing nozzle (2) is connected to a high-pressure gas pump (8) through a pipe (2), and the pneumatic atomizing nozzle (2) is connected to a metering pump (9) through a pipe (3). The pneumatic atomizing nozzle (2), metering pump (6), metering pump (9), high-speed stirring paddle (3), pH sensor (4), and high-pressure gas pump (8) are all electrically connected to the electrical control system module (10).

2. The apparatus for preparing lignin micro / nanoparticles based on microfluidic atomization according to claim 1, characterized in that, The volume of the reactor (1) is 80-120L.

3. The apparatus for preparing lignin micro / nanoparticles based on microfluidic atomization according to claim 1, characterized in that, The height of the pneumatic atomizing nozzle (2) at the top of the reactor (1) is adjustable, with an adjustment range of 1-30 cm in the vertical direction.

4. The apparatus for preparing lignin micro / nanoparticles based on microfluidic atomization according to claim 1, characterized in that, The pneumatic atomizing nozzle (2) is provided with several circular holes, and the angle between the perpendicular line of the plane where the circular holes are located and the direction of the vertical axis of the pneumatic atomizing nozzle (2) is 15-45°.

5. The apparatus for preparing lignin micro / nanoparticles based on microfluidic atomization according to claim 1, characterized in that, The blade length of the high-speed stirring paddle (3) is 5-10cm.

6. The apparatus for preparing lignin micro / nanoparticles based on microfluidic atomization according to claim 1, characterized in that, The high-speed stirring paddle (3) is located at the bottom center of the reactor (1); the feed inlet (5) is located at two-thirds of the height of the side of the reactor (1).

7. The apparatus for preparing lignin micro / nanoparticles based on microfluidic atomization according to claim 1, characterized in that, The diameters of pipe one (11), pipe two (12), and pipe three (13) are all 2-5 mm.

8. The apparatus for preparing lignin micro / nanoparticles based on microfluidic atomization according to claim 1, characterized in that, The material of the reactor (1) is acid-resistant tetrafluoroethylene, or the reactor (1) is composed of a metal body and an acid-resistant and corrosion-resistant coating on the inner wall.

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