A device and method for separating all components of wood fibers and improving enzymatic hydrolysis efficiency

Abstract

The application discloses a device and method for separating all components of wood fiber and improving enzymatic hydrolysis efficiency, and belongs to the technical field of biomass resource utilization. The device comprises an electric heating reaction unit. A time-varying magnetic field in the magnetic core in the electric heating reaction unit is used as an excitation source to spontaneously induce electric effect and thermal effect on reaction liquid in the reaction tube, so that electric heating cooperative treatment is completed. The method comprises the following steps: mixing wood fiber raw materials with a dilute acid or dilute alkali solution, and then performing electric heating pretreatment by using the device. The electric heating coupling dilute acid pretreatment can remove a large amount of hemicellulose and a small amount of lignin in the wood fiber, and the electric heating coupling dilute alkali pretreatment can remove a large amount of lignin and a small amount of hemicellulose in the wood fiber. The application aims to separate cellulose, hemicellulose and lignin in the wood fiber, and improve the enzymatic hydrolysis efficiency of lignocellulose.

Description

Technical Field

[0001] This invention belongs to the field of biomass resource utilization technology, and specifically relates to an apparatus and method for separating all components of lignocellulose and improving enzymatic hydrolysis efficiency. Background Technology

[0002] The high demand for clean technologies, sustainable strategies, and eco-friendly processing has led to a resurgence in the development of alternative chemicals and materials that can mitigate environmental pollution and resource scarcity globally. Lignocellulosic biomass, existing as agricultural and forestry waste, is a promising renewable resource with immense potential for the sustainable production of a wide range of high-value biomaterials. The main components of lignocellulosic biomass are hemicellulose, cellulose, and lignin, all of which are recyclable carbon sources. It is estimated that tens of billions of tons of lignocellulosic acid are produced worldwide annually. However, due to its complex composition and persistent cross-linked chemical structure, this potential value remains largely untapped. Therefore, unlocking this potential requires a suitable and efficient separation process capable of accommodating the structural complexity of lignocellulosic acid and extracting value from all its major components.

[0003] In the fields of biomass resource utilization and biorefining, pretreatment is a crucial step in the entire process. It can break down the naturally stubborn structure of lignocellulose biomass and fractionate its three main components. However, due to the contradictory nature of hemicellulose and lignin—hemicellulose is easily degraded while lignin is difficult to extract—one-step pretreatment technologies cannot achieve complete conversion of all components. In single pretreatment methods, most studies have focused on the intensive removal of lignin to obtain digestible, cellulose-rich substrates. These processes often lead to the degradation of cellulose / hemicellulose into oligomers, sugar monomers, and other small molecule byproducts or inhibitors, adding additional technical challenges to their subsequent utilization.

[0004] To address the challenges of easily degradable cellulose and difficult lignin separation, processes combining hydrothermal pretreatment and chemical extraction have been proposed to achieve value-added utilization of all components of lignocellulose. Existing chemical extraction uses solvent systems including ionic liquids, eutectic solvents, organic solvents, and various acid-base systems. These solvents are not only costly and toxic but also have adverse environmental impacts. Hydrothermal pretreatment is an environmentally friendly and low-cost extraction and separation technology that can depolymerize hemicellulose and soften expanded lignin, providing a more fragile biomass structure for chemical extraction. However, existing hydrothermal pretreatment technologies rely on pressurized and high-temperature reactors or autoclaves, imposing stringent equipment requirements and hindering large-scale production. For example, CN 115142288 A discloses a method for rapidly separating all components of lignocellulose biomass using an alkaline eutectic solvent, which pretreats the mixture of lignocellulose and alkaline eutectic solvent in a microwave reactor at a heat treatment temperature of 80-160℃; CN 111154817A discloses a method for efficiently separating and enzymatically hydrolyzing lignocellulose using an ionic liquid-high-boiling alcohol composite system, which pretreats the mixture of proton-type ionic liquid and high-boiling alcohol at 100-140℃; CN 111826986 A discloses a method for efficiently separating all components of lignocellulose, which uses a CO2-assisted hydrothermal method to degrade hemicellulose in lignocellulose at 180-200℃, and then uses an eutectic solvent at 100-140℃ to separate cellulose and lignin. The aforementioned pretreatment processes are all relatively advanced technologies, but they have the following problems: (1) Existing chemical extraction processes cannot avoid costly and environmentally unfriendly solvent systems; (2) Traditional hydrothermal treatment equipment requires the use of reactors or reaction vessels to achieve a pressurized and high-temperature environment, making it difficult to process in large quantities; (3) The pretreatment temperature of most processes is too high, which can easily lead to the formation of inhibitors and affect subsequent separation, saccharification, and fermentation. Therefore, there is an urgent need for a device and process for the pretreatment of lignocellulose raw materials that is both green and environmentally friendly, easy to operate, and can be mass-produced. Summary of the Invention

[0005] To address the aforementioned problems, the main objective of this invention is to provide an apparatus and method for achieving complete separation of lignocellulose components and improving enzymatic hydrolysis and saccharification efficiency, thereby overcoming the shortcomings of the prior art.

[0006] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0007] The present invention provides an apparatus for realizing the separation of all components of lignocellulose and improving the efficiency of enzymatic hydrolysis and saccharification. The apparatus consists of an electrothermal reaction unit 100, a pumping device 200, a stirring device 300, a power supply device 400, and a cooling device 500.

[0008] The electrothermal reaction unit 100 is composed of reaction tubes 101-102, magnetic core 103, water-cooled plate 104, and excitation coil 105;

[0009] The magnetic core 103 is a ring-shaped plate-shaped magnetic conductive material with a hole in the middle; the water-cooling plate 104 is a ring-shaped plate-shaped metal material with a hole in the middle, which is placed alternately with the magnetic core; cooling pipes 201-202 are embedded in the outer edge of the water-cooling plate 104 to allow coolant to circulate.

[0010] The water-cooled plate 104 is connected to the cooling device 500 via cooling pipes 201-202; the cooling device 500 is used to cool the coolant in the pipes 201-202.

[0011] The reaction tubes 101-102 pass through the middle hole of the magnetic core 103 and the water-cooled plate 104 and are wound around the magnetic core and the water-cooled plate; the inlet end 101 of the reaction tube is located at the bottom end of the electrothermal reaction unit and is connected to the pumping device 200; the outlet end 102 of the reaction tube is located at the top end of the electrothermal reaction unit and is connected to the stirring device 300 through a pipe.

[0012] The excitation coil 105 is wound around the magnetic core 103 and connected to the power supply device 400; the power supply device 400 is used to provide excitation voltage, so that the magnetic core 103 generates a time-varying magnetic field as an excitation source, and spontaneously induces voltage and current inside the reaction tubes 101-102.

[0013] The stirring device 300 and the pumping device 200 are connected by a pipe, and the pipe of the pumping device contacts the bottom of the container in the stirring device to ensure the pumping of the solution.

[0014] Furthermore, the material of the magnetic core 103 is an amorphous nanocrystalline soft magnetic material.

[0015] Furthermore, in the magnetic core 103, the length L1 is 30-100cm, the width W1 is 15-50cm, the height H is 3-8cm, the distance l1 from the middle hole to the width is 5-20cm, and the distance w1 from the middle hole to the length is 5-20cm.

[0016] Furthermore, the diameter of the reaction tubes 101-102 ranges from 10mm to 50mm.

[0017] Furthermore, the reaction tubes 101-102 are made of acid and alkali resistant glass or silicone tubes.

[0018] The application of the device provided by this invention in the field of wood fiber separation.

[0019] In another aspect, the present invention provides a method for achieving complete separation of lignocellulose components and improving enzymatic hydrolysis saccharification efficiency, wherein the method is performed using the aforementioned apparatus for achieving complete separation of lignocellulose components and improving enzymatic hydrolysis saccharification efficiency;

[0020] The method specifically includes the following steps:

[0021] (1) Wash the wood fiber raw material to remove the surface ash, then immerse it in an organic solvent for decolorization, then dry it and crush it;

[0022] (2) Place the pulverized wood fiber raw material and dilute acid solution from step (1) into the above stirring device, turn on the stirring to mix, and after the mixture is evenly mixed, turn on the pumping device to send the mixture into the reaction tube, turn on the power device and cooling device to carry out the reaction.

[0023] (3) After the reaction in step (2) is completed, the reaction mixture is subjected to solid-liquid separation. The obtained solid is washed until it is electrically neutral and dried to obtain a dry solid residue. The supernatant obtained is hydrolyzed and purified to obtain crude xylose solid.

[0024] (4) Place the dried solid residue and dilute alkaline solution from step (3) into the above stirring device, turn on the stirring to mix, and after the mixture is evenly mixed, turn on the pumping device to send the mixture into the reaction tube, turn on the power supply and cooling device to carry out the reaction.

[0025] (5) After the reaction in step (4) is completed, solid-liquid separation is performed. The obtained solid is washed until it is electrically neutral, dried, and dried solid residue is obtained. The supernatant obtained is adjusted to pH 1-3 with acid solution and filtered to obtain solid components, which is lignin.

[0026] (6) Mix the dried solid residue from step (5) with acetate buffer solution and add cellulase to perform enzymatic hydrolysis to obtain glucose.

[0027] Furthermore, the wood fiber raw materials mentioned in step (1) include straw and wood chips.

[0028] Furthermore, the straw includes wheat straw and corn straw.

[0029] Furthermore, the wood chips include poplar wood chips, eucalyptus wood chips, sugarcane bagasse, and bamboo powder.

[0030] Furthermore, the organic solvent mentioned in step (1) includes ethanol.

[0031] Furthermore, the mesh size of the powder in step (1) is 30 to 80 mesh.

[0032] Furthermore, the dilute acid solution mentioned in step (2) includes one or more of dilute sulfuric acid and dilute hydrochloric acid.

[0033] Furthermore, the concentration of the dilute acid solution in step (2) is 0.5%-3%.

[0034] Furthermore, the mass-to-volume ratio of the pulverized wood fiber raw material and the dilute acid solution in step (2) is 1g:10-50mL.

[0035] Furthermore, in step (2), the reaction temperature is 90-100℃ and the treatment time is 3-7h.

[0036] Furthermore, in step (2), the parameters of the power supply device are set as follows: voltage 100-800V, current 2-10A, and power 0.2-8KW.

[0037] Furthermore, in step (2), the ratio of the voltage of the power supply device to the diameter of the reaction tubes 101-102 is 200-250V:10mm.

[0038] Furthermore, after the power supply is turned on in step (2), the magnetic field strength of the magnetic core is 0.5-2T.

[0039] Furthermore, the dilute alkaline solution mentioned in step (4) includes one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, sodium bicarbonate, and ammonia water.

[0040] Furthermore, the concentration of the dilute alkaline solution in step (4) is 0.5%-3%.

[0041] Furthermore, the mass-to-volume ratio of the dried solid residue to the dilute alkaline solution in step (4) is 1g:10-50mL.

[0042] Furthermore, in step (4), the reaction temperature is 50-90℃ and the treatment time is 3-7h.

[0043] Furthermore, in step (4), the parameters of the power supply device are set as follows: voltage 100-800V, current 2-10A, and power 0.2-8KW.

[0044] Furthermore, in step (4), the ratio of the voltage of the power supply device to the diameter of the reaction tubes 101-102 is 200-250V:10mm.

[0045] Furthermore, after the power supply is turned on in step (4), the magnetic field strength of the magnetic core is 0.5-2T.

[0046] Furthermore, in step (5), the acid solution is a sulfuric acid solution with a concentration of 65-80%.

[0047] Furthermore, in step (6), the acetate in the acetate buffer solution includes one or more of sodium acetate, potassium acetate, and ammonium acetate.

[0048] Furthermore, in step (6), the concentration of acetate in the acetate buffer solution is 0.01-0.1 mol / L.

[0049] Furthermore, in step (6), the mass-to-volume ratio of the dried solid residue to the acetate buffer solution is 1 g: 30-70 mL.

[0050] Furthermore, in step (6), the amount of cellulase added is 10-30 FPU / g substrate.

[0051] Furthermore, the enzymatic hydrolysis conditions in step (6) are a temperature of 40-55℃, a rotation speed of 100-150rpm, and a time of 48-72h.

[0052] Beneficial effects

[0053] 1) This invention provides a novel device in which the electrothermal reaction unit uses induction heating, which avoids the energy consumption of heat transfer in the medium during traditional hydrothermal treatment, greatly improves the thermal energy utilization rate, reduces the traditional hydrothermal pretreatment temperature, controls the pretreatment temperature to within 100°C, and avoids the requirements of high temperature and high pressure environment on equipment or device.

[0054] 2) This invention, combined with the use of a novel device, designs a two-step acid-base coupled electrothermal pretreatment, which realizes the separation of all components of cellulose, hemicellulose and lignin in wood fiber raw materials, and does not involve the use of organic solvents or catalysts throughout the process, thus reducing pollution. Attached Figure Description

[0055] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0056] Figure 1 This is a schematic diagram of the overall structure of a device for realizing the separation of all components of lignocellulose and improving the efficiency of enzymatic hydrolysis and saccharification, provided in a typical embodiment of the present invention; in the figure: electrothermal reaction unit (100), pumping device (200), stirring device (300), power supply device (400), cooling device (500).

[0057] Figure 2This is a schematic diagram of the electrothermal reaction unit and its top view, magnetic core, and water-cooled plate in a device for realizing the separation of all components of lignocellulose and improving the efficiency of enzymatic hydrolysis and saccharification, provided in a typical embodiment of the present invention; reaction tube (101-102), magnetic core (103), water-cooled plate (104), excitation coil (105) and condensate pipe (201-202).

[0058] Figure 3 The left side shows the effects of electrothermal pretreatment and hydrothermal pretreatment provided in Embodiment 2 and Comparative Example 1 on the retention rate of cellulose, the removal rate of hemicellulose and lignin in lignocellulose. Figure 3 The right side shows a comparison of enzymatic hydrolysis efficiency.

[0059] Figure 4 The left side shows the effects of electrothermal pretreatment and hydrothermal pretreatment provided in Example 3 and Comparative Example 2 on the retention rate of cellulose, the removal rate of hemicellulose and lignin in lignocellulose. Figure 4 The right side shows a comparison of enzymatic hydrolysis efficiency.

[0060] Figure 5 The left side shows the effects of electrothermal pretreatment and hydrothermal pretreatment provided in Example 4 and Comparative Example 3 on the retention rate of cellulose, the removal rate of hemicellulose and lignin in lignocellulose. Figure 5 The right side shows a comparison of enzymatic hydrolysis efficiency. Detailed Implementation

[0061] In view of the shortcomings of the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. The following will further explain and illustrate this technical solution, its implementation process, and its principles.

[0062] The following will further explain the technical solution, its implementation process and principle in conjunction with the accompanying drawings and specific implementation examples. Unless otherwise specified, the power supply device, pumping device, electrothermal reaction unit, stirring device, cooling device, magnetic core, water-cooled plate and other components used in this invention are all known to those skilled in the art and can be obtained commercially. No specific product models or structures are limited here.

[0063] Source of raw materials

[0064] Cellulase (400u / mg) and filter paper enzyme activity (250FPU / g) were purchased from Shanghai Yuanye Biotechnology Co., Ltd.; wheat straw was sourced from Donghai County, Lianyungang City, Jiangsu Province.

[0065] Example 1

[0066] This embodiment provides a device for achieving complete component separation of lignocellulose and improving enzymatic hydrolysis and saccharification efficiency, as shown in the attached diagram. Figure 1As shown, its components include an electrothermal reaction unit 100, a pumping device 200, a stirring device 300, a power supply device 400, and a cooling device 500.

[0067] In this device, the electrothermal reaction unit 100, as shown in the attached... Figure 2 As shown, the system comprises reaction tubes 101-102, a magnetic core 103, a water-cooled plate 104, and an excitation coil 105. The electrothermal reaction unit 100 generates a time-varying magnetic field as an excitation source, spontaneously inducing an induced voltage and current within the reaction tubes 101-102. The induced voltage acts on the reaction liquid to produce an electrical effect, and the induced current acts on the reaction liquid to produce a thermal effect, completing the electrothermal synergistic reaction. The pumping device 200 transports the liquid from the stirring device 300 into the reaction tubes 101-102 for the electrothermal synergistic reaction. The stirring device 300 stirs the liquid to maintain its uniformity. The stirring device 300 is connected to the pumping device 200 via a pipe, and the pipe of the pumping device contacts the bottom of the container in the stirring device to ensure the pumping of the solution. The power supply device 400 provides excitation voltage to the magnetic core 103 through the excitation coil 105. The cooling device 500 cools the cooling water in the cooling tubes 201-202.

[0068] In the electrothermal reaction unit 100, the magnetic core 103 is a rectangular annular plate-shaped magnetic material with a hole in the middle; the water-cooled plate 104 is a rectangular annular plate-shaped metal material with a hole in the middle, which is placed alternately with the magnetic core 103 to facilitate the dissipation of heat generated by eddy current loss and hysteresis loss in the magnetic core through the water-cooled plate; cooling pipes 201-202 are embedded in the four sides of the water-cooled plate 104 for cooling water circulation; the water-cooled plate 104 is connected to the cooling device 500 through the cooling pipes 201-202; the reaction tubes 101-102 The magnetic core 103 and the water-cooled plate 104 are passed through the middle hole and wound around the magnetic core 103 and the water-cooled plate 104; the inlet end 101 of the reaction tube is located at the bottom end of the electrothermal reaction unit 100 and is connected to the pumping device 200 through a pipe to facilitate filling the pipe with liquid during transportation; the outlet end 102 of the reaction tube is located at the top end of the electrothermal reaction unit 100 and is connected to the stirring device 300 through a pipe to circulate the liquid to the stirring device 300; the excitation coil 105 is wound on the magnetic core 103 and connected to the power supply device 400.

[0069] The device is operated as follows: First, turn on the stirring device 300 to maintain the uniformity of the reaction liquid. Then, start the pumping device 200 to inject the reaction liquid into the reaction tubes 101-102. When liquid begins to flow out of the outlet 102 of the reaction tube, the reaction tube is full. At this time, the power supply device 400 is turned on, providing excitation voltage to the magnetic core 103 through the excitation coil 105. The time-varying magnetic field inside the magnetic core 103 acts as an excitation source, spontaneously inducing an induced voltage and current inside the reaction tubes 101-102, initiating an electrothermal synergistic reaction. Then, start the cooling device 500 to circulate cooling water to cool the device. The number of water-cooled plates 104 and magnetic cores 103 can be adjusted according to the actual application.

[0070] Example 2

[0071] This embodiment uses the method provided by the present invention, such as... Figure 1 and Figure 2 The device shown uses a reaction tube with a diameter of 10mm, made of silicone; it uses magnetic cores with L1 of 30cm, l1 of 6cm, W1 of 18cm, w1 of 6cm, and H of 3cm; the size of the water-cooled plate is similar to that of the magnetic core; the electrothermal reaction unit uses 3 magnetic cores and 2 water-cooled plates, with the water-cooled plates placed between the two magnetic cores for heat dissipation.

[0072] The method for achieving complete separation of lignocellulose components and improving enzymatic hydrolysis saccharification efficiency in this embodiment includes the following steps:

[0073] (1) Dilute acid coupled with electrothermal pretreatment: 25g of crushed wheat straw powder (50 mesh) was mixed with 1L of dilute sulfuric acid solution (1% concentration) to obtain a mixed liquid. The mixed liquid was then placed in a stirring device and pumped into an electrothermal reaction unit for electrothermal circulation treatment (the temperature during electrothermal circulation treatment was 90℃, the treatment time was 5h; the power supply provided a voltage of 200V, a current of 5A, and a power of 1KW). The treated mixed liquid was then subjected to solid-liquid separation. The solid residue (wood fiber) was washed until electrically neutral and dried by forced air for subsequent dilute alkali pretreatment. The supernatant was hydrolyzed (121℃, 1h), rotary evaporated, extracted, and separated to obtain crude xylose solid.

[0074] (2) Dilute alkali coupled electrothermal pretreatment: 25g of solid residue after drying in step (1) was mixed with 1L of sodium hydroxide solution (1% solution concentration) to obtain a mixed liquid. The mixed liquid was then placed in a stirring device and pumped into an electrothermal reaction unit for electrothermal circulation treatment (the treatment temperature was 70℃ and the treatment time was 5h; the power supply provided a voltage of 200V, a current of 5A, and a power of 1KW). The treated mixed liquid was subjected to solid-liquid separation. The solid residue (wood fiber) was washed until electrically neutral and dried in the air for subsequent enzymatic hydrolysis and saccharification. 72% sulfuric acid solution was added to the supernatant until the pH was 2. The supernatant was left overnight to precipitate lignin. Then, it was vacuum filtered, and the retained lignin solid components were washed with acidified warm water and dried at 50℃ to obtain lignin.

[0075] (3) Enzymatic hydrolysis of lignocellulose: The solid residue after drying in step (2) was mixed with acetate buffer solution (0.05 mol / L) (solid-liquid ratio of 1:50) and a certain amount of cellulase (20 FPU / g substrate) was added. The mixture was enzymatically hydrolyzed at 50℃ and 150 rpm for a period of time (12, 24, 36, 48, 72 h) to obtain glucose and determine the hydrolysis rate.

[0076] The untreated wheat straw contained 33.3% cellulose, 22.7% hemicellulose, and 20.6% lignin. After a two-step electrothermal coupled dilute acid-base pretreatment, the cellulose retention rate was 76.8%, the hemicellulose removal rate was 89.4%, and the lignin removal rate was 91.7%. The enzymatic hydrolysis rates of the pretreated wheat straw after 12, 24, 36, 48, and 72 hours were 47.5%, 67.2%, 78.6%, 85.9%, and 94.1%, respectively.

[0077] Example 3

[0078] Using the invention provided as follows Figure 1 and Figure 2 The device shown uses a reaction tube with a diameter of 10mm, made of silicone; it uses magnetic cores with L1 of 30cm, l1 of 6cm, W1 of 18cm, w1 of 6cm, and H of 83cm; the size of the water-cooled plate is similar to that of the magnetic core; the electrothermal reaction unit uses 3 magnetic cores and 2 water-cooled plates, with the water-cooled plates placed between the two magnetic cores for heat dissipation.

[0079] The method for achieving complete separation of lignocellulose components and improving enzymatic hydrolysis saccharification efficiency in this embodiment includes the following steps:

[0080] (1) Dilute acid coupled with electrothermal pretreatment: 25g of crushed wheat straw powder (50 mesh) was mixed with 1L of dilute sulfuric acid solution (solution concentration of 2%) to obtain a mixed liquid. The mixed liquid was then placed in a stirring device and pumped into an electrothermal reaction unit for electrothermal circulation treatment (the treatment temperature was 90℃, the treatment time was 3h; the power supply provided a voltage of 200V, a current of 5A, and a power of 1KW). The treated mixed liquid was then subjected to solid-liquid separation. The solid residue (wood fiber) was washed until electrically neutral and dried by forced air for subsequent dilute alkali pretreatment. The supernatant was hydrolyzed (121℃, 1h), rotary evaporated, extracted, and separated to obtain crude xylose solid.

[0081] (2) Dilute alkali coupled electrothermal pretreatment: 25g of solid residue after drying in step (1) was mixed with 1L of sodium hydroxide solution (solution concentration of 2%) to obtain a mixed liquid. The mixed liquid was then placed in a stirring device and pumped into an electrothermal reaction unit for electrothermal circulation treatment (the treatment temperature was 70℃, the treatment time was 3h; the power supply provided the voltage was 200V, the current was 5A, and the power was 1KW). The treated mixed liquid was then subjected to solid-liquid separation. The solid residue (wood fiber) was washed until electrically neutral and dried in the air for subsequent enzymatic hydrolysis and saccharification. The supernatant was added with 72% sulfuric acid solution until the pH was 2 and left overnight to precipitate lignin. Then, it was vacuum filtered, and the retained lignin solid components were washed with acidified warm water and dried at 50℃ to obtain lignin.

[0082] (3) Lignocellulose enzymatic hydrolysis: The solid residue after air drying in step (2) was mixed with acetate buffer solution (0.05 mol / L) (solid-liquid ratio of 1:50) and cellulase (20 FPU / g substrate) was added. The mixture was enzymatically hydrolyzed at 50℃ and 150 rpm for a period of time (12, 24, 36, 48, 72 h) to obtain glucose and determine the hydrolysis rate.

[0083] The untreated wheat straw contained 33.3% cellulose, 22.7% hemicellulose, and 20.6% lignin. After a two-step electrothermal coupled dilute acid-base pretreatment, the cellulose retention rate was 74.2%, the hemicellulose removal rate was 90.7%, and the lignin removal rate was 93.5%. The enzymatic hydrolysis rates of the pretreated wheat straw after 12, 24, 36, 48, and 72 hours were 50.2%, 69.7%, 81.5%, 90.6%, and 96.9%, respectively.

[0084] Example 4

[0085] Using the invention provided as follows Figure 1 and Figure 2The device shown uses a reaction tube with a diameter of 20mm, made of silicone; it uses magnetic cores with L1 of 60cm, l1 of 15cm, W1 of 30cm, w1 of 10cm, and H of 5cm; the size of the water-cooled plate is similar to that of the magnetic core; the electrothermal reaction unit uses 8 magnetic cores and 7 water-cooled plates, with the water-cooled plates placed between the two magnetic cores for heat dissipation.

[0086] The method for achieving complete separation of lignocellulose components and improving enzymatic hydrolysis saccharification efficiency in this embodiment includes the following steps:

[0087] (1) Dilute acid coupled with electrothermal pretreatment: 500g of crushed wheat straw powder (50 mesh) was mixed with 1L of dilute sulfuric acid solution (1% concentration) to obtain a mixed liquid. The mixed liquid was then placed in a stirring device and pumped into an electrothermal reaction unit for electrothermal circulation treatment (the treatment temperature was 90℃ and the treatment time was 5h; the power supply provided a voltage of 500V, a current of 10A, and a power of 5KW). The treated mixed liquid was then subjected to solid-liquid separation. The solid residue (wood fiber) was washed until electrically neutral and dried by forced air for subsequent dilute alkali pretreatment. The supernatant was hydrolyzed (121℃, 1h), rotary evaporated, extracted, and separated to obtain crude xylose solid.

[0088] (2) Dilute alkali coupled electrothermal pretreatment: 500g of solid residue after drying in step (1) was mixed with 1L of sodium hydroxide solution (1% solution concentration) to obtain a mixed liquid. The mixed liquid was then placed in a stirring device and pumped into an electrothermal reaction unit for electrothermal circulation treatment (the treatment temperature was 70℃, the treatment time was 5h; the power supply provided a voltage of 500V, a current of 10A, and a power of 5KW). The treated mixed liquid was then subjected to solid-liquid separation. The solid residue (wood fiber) was washed until electrically neutral and dried in the air for subsequent enzymatic hydrolysis and saccharification. 72% sulfuric acid solution was added to the supernatant until the pH was 2. The supernatant was left overnight to precipitate lignin. The supernatant was then vacuum filtered, and the remaining lignin solid components were washed with acidified warm water and dried at 50℃ to obtain lignin.

[0089] (3) Lignocellulose enzymatic hydrolysis: The solid residue after air drying in step (2) was mixed with acetate buffer solution (0.05 mol / L) (solid-liquid ratio of 1:50) and cellulase (20 FPU / g substrate) was added. The mixture was enzymatically hydrolyzed at 50℃ and 150 rpm for a period of time (12, 24, 36, 48, 72 h) to obtain glucose and determine the hydrolysis rate.

[0090] The untreated wheat straw contained 33.3% cellulose, 22.7% hemicellulose, and 20.6% lignin. After a two-step electrothermal coupled dilute acid-base pretreatment, the cellulose retention rate was 78.2%, the hemicellulose removal rate was 88.7%, and the lignin removal rate was 90.3%. The enzymatic hydrolysis rates of the pretreated wheat straw after 12, 24, 36, 48, and 72 hours were 46.5%, 64.3%, 75.9%, 83.1%, and 92.7%, respectively.

[0091] Comparative Example 1

[0092] The specific implementation method is the same as that in Example 2, except that: Comparative Example 1 directly uses a hydrothermal treatment device, employing a laboratory-grade circulating water bath for operation. The specific operation steps are as follows:

[0093] (1) Dilute acid coupled hydrothermal pretreatment: 25g of crushed wheat straw powder (50 mesh) was mixed with 1L of dilute sulfuric acid solution (1% concentration) to obtain a mixed liquid. The mixed liquid was then placed in a glass bottle and mixed evenly on a magnetic stirring device. The mixed liquid was pumped into a circulating water bath chamber by a peristaltic pump for hydrothermal circulation treatment (the treatment temperature was 90℃ and the treatment time was 5h). The treated mixed liquid was subjected to solid-liquid separation. The solid residue (wood fiber) was washed until electrically neutral and dried by forced air for subsequent dilute alkali pretreatment. The supernatant was hydrolyzed (121℃, 1h), rotary evaporated, extracted and separated to obtain crude xylose solid.

[0094] (2) Dilute alkali coupled electrothermal pretreatment: 25g of solid residue after drying in step (1) was mixed with 1L of sodium hydroxide solution (1% solution concentration) to obtain a mixed liquid. The mixed liquid was then placed in a glass bottle and mixed evenly on a magnetic stirring device. The mixed liquid was pumped into a circulating water bath chamber by a peristaltic pump for hydrothermal circulation treatment (the treatment temperature was 70℃ and the treatment time was 5h). The treated mixed liquid was subjected to solid-liquid separation. The solid residue (wood fiber) was washed until electrically neutral and dried in the air for enzymatic hydrolysis and saccharification. 72% sulfuric acid solution was added to the supernatant until the pH was 2. The supernatant was left overnight to precipitate lignin. Then, it was vacuum filtered, and the retained lignin solid components were washed with acidified warm water and dried at 50℃ to obtain lignin.

[0095] (3) Lignocellulose enzymatic hydrolysis: The solid residue after air drying in step (2) was mixed with acetate buffer solution (0.05 mol / L) (solid-liquid ratio of 1:50) and cellulase (20 FPU / g substrate) was added. The mixture was enzymatically hydrolyzed at 50℃ and 150 rpm for a period of time (12, 24, 36, 48, 72 h) to obtain glucose and determine the hydrolysis rate.

[0096] The untreated wheat straw contained 33.3% cellulose, 22.7% hemicellulose, and 20.6% lignin. After a two-step electrothermal coupled dilute acid-base pretreatment, the cellulose retention rate was 80.9%, the hemicellulose removal rate was 58.3%, and the lignin removal rate was 64.5%. The enzymatic hydrolysis rates of the pretreated wheat straw after 12, 24, 36, 48, and 72 hours were 22.3%, 29.7%, 48.1%, 62.4%, and 69.6%, respectively.

[0097] Comparative Example 2

[0098] The specific implementation method is the same as in Example 3, except that: Comparative Example 2 directly uses a hydrothermal treatment device, employing a laboratory-grade circulating water bath for operation. The specific operation steps are as follows:

[0099] (1) Dilute acid coupled hydrothermal pretreatment: 25g of crushed wheat straw powder (50 mesh) was mixed with 1L of dilute sulfuric acid solution (solution concentration of 2%) to obtain a mixed liquid. The mixed liquid was then placed in a glass bottle and mixed evenly on a magnetic stirring device. The mixed liquid was pumped into a circulating water bath chamber by a peristaltic pump for hydrothermal circulation treatment (the treatment temperature was 90℃ and the treatment time was 3h). The treated mixed liquid was subjected to solid-liquid separation. The solid residue (wood fiber) was washed until electrically neutral and dried by forced air for subsequent dilute alkali pretreatment. The supernatant was hydrolyzed (121℃, 1h), rotary evaporated, extracted and separated to obtain crude xylose solid.

[0100] (2) Dilute alkali coupled electrothermal pretreatment: 25g of solid residue after drying in step (1) was mixed with 1L of sodium hydroxide solution (solution concentration of 2%) to obtain a mixed liquid. The mixed liquid was then placed in a glass bottle and mixed evenly on a magnetic stirring device. The mixed liquid was pumped into a circulating water bath chamber by a peristaltic pump for hydrothermal circulation treatment (the treatment temperature was 70℃ and the treatment time was 3h). The treated mixed liquid was subjected to solid-liquid separation. The solid residue (wood fiber) was washed until electrically neutral and dried in the air for enzymatic hydrolysis and saccharification. 72% sulfuric acid solution was added to the supernatant until the pH was 2. The supernatant was left overnight to precipitate lignin. Then, it was vacuum filtered, and the retained lignin solid components were washed with acidified warm water and dried at 50℃ to obtain lignin.

[0101] (3) Lignocellulose enzymatic hydrolysis: The solid residue after air drying in step (2) was mixed with acetate buffer solution (0.05 mol / L) (solid-liquid ratio of 1:50) and cellulase (20 FPU / g substrate) was added. The mixture was enzymatically hydrolyzed at 50℃ and 150 rpm for a period of time (12, 24, 36, 48, 72 h) to obtain glucose and determine the hydrolysis rate.

[0102] The untreated wheat straw contained 33.3% cellulose, 22.7% hemicellulose, and 20.6% lignin. After a two-step electrothermal coupled dilute acid-base pretreatment, the cellulose retention rate was 78.5%, the hemicellulose removal rate was 61.4%, and the lignin removal rate was 65.7%. The enzymatic hydrolysis rates of the pretreated wheat straw after 12, 24, 36, 48, and 72 hours were 27.7%, 46.8%, 61.4%, 70.3%, and 75.6%, respectively.

[0103] Comparative Example 3

[0104] The specific implementation method is the same as in Example 4, except that: Comparative Example 3 directly uses a hydrothermal treatment device, and an industrial-grade reactor is used instead of the hydrothermal treatment device for operation. The specific operation steps are as follows:

[0105] (1) Dilute acid coupled hydrothermal pretreatment: 250g of crushed wheat straw powder (50 mesh) was mixed with 10L of dilute sulfuric acid solution (1% concentration) to obtain a mixed liquid. The mixed liquid was then placed in a glass bottle and mixed evenly on a magnetic stirring device. The mixed liquid was pumped into a circulating water bath chamber by a peristaltic pump for hydrothermal circulation treatment (the treatment temperature was 90℃ and the treatment time was 5h). The treated mixed liquid was subjected to solid-liquid separation. The solid residue (wood fiber) was washed until electrically neutral and dried by forced air for subsequent dilute alkali pretreatment. The supernatant was hydrolyzed (121℃, 1h), rotary evaporated, extracted and separated to obtain crude xylose solid.

[0106] (2) Dilute alkali coupled electrothermal pretreatment: 250g of solid residue after drying in step (1) was mixed with 10L of sodium hydroxide solution (1% solution concentration) to obtain a mixed liquid. The mixed liquid was then placed in a glass bottle and mixed evenly on a magnetic stirring device. The mixed liquid was pumped into a circulating water bath chamber by a peristaltic pump for hydrothermal circulation treatment (the treatment temperature was 70℃ and the treatment time was 5h). The treated mixed liquid was subjected to solid-liquid separation. The solid residue (wood fiber) was washed until electrically neutral and dried in the air for enzymatic hydrolysis and saccharification. 72% sulfuric acid solution was added to the supernatant until the pH was 2. The supernatant was left overnight to precipitate lignin. Then, it was vacuum filtered, and the retained lignin solid components were washed with acidified warm water and dried at 50℃ to obtain lignin.

[0107] (3) Lignocellulose enzymatic hydrolysis: The solid residue after air drying in step (2) was mixed with acetate buffer solution (0.05 mol / L) (solid-liquid ratio of 1:50) and cellulase (20 FPU / g substrate) was added. The mixture was enzymatically hydrolyzed at 50℃ and 150 rpm for a period of time (12, 24, 36, 48, 72 h) to obtain glucose and determine the hydrolysis rate.

[0108] The untreated wheat straw contained 33.3% cellulose, 22.7% hemicellulose, and 20.6% lignin. After a two-step electrothermal coupled dilute acid-base pretreatment, the cellulose retention rate was 81.4%, the hemicellulose removal rate was 56.8%, and the lignin removal rate was 63.1%. The enzymatic hydrolysis rates of the pretreated wheat straw after 12, 24, 36, 48, and 72 hours were 18.7%, 26.4%, 47.2%, 60.6%, and 67.9%, respectively.

[0109] Table 1. Pretreatment results and enzymatic hydrolysis rates of Examples 2-4 and Comparative Examples 1-3

[0110]

[0111] In summary, as shown in Table 1 and Appendix Figures 3-5 As shown, compared with Comparative Examples 1, 2, and 3, Examples 2, 3, and 4 respectively, show that electrothermal pretreatment is more effective than hydrothermal pretreatment in removing hemicellulose and lignin from wood fibers. Moreover, the enzymatic hydrolysis efficiency of wood fibers after electrothermal pretreatment is significantly higher than that of the hydrothermal pretreatment group. Targeting the removal rate of hemicellulose and lignin in wood fibers and the enzymatic hydrolysis efficiency of wood fibers, the advantages of the device and method of the present invention for achieving full component separation of wood fibers and improving enzymatic saccharification efficiency are demonstrated. Compared with traditional hydrothermal treatment, the device and method of the present invention also improve energy utilization.

[0112] Comparative Example 4

[0113] This comparative example is a comparison with Example 2. The same device as Example 2 is used, except that the voltage in step (1) is adjusted from 200V to 400V, while other operations and parameters remain unchanged.

[0114] Table 2. Preprocessing results of Example 2 and Comparative Example 4

[0115]

[0116] As can be seen from Table 2, when the voltage is adjusted to 400V, the response of thermal and electrical effects is enhanced, and the removal rate of hemicellulose in wheat straw is further improved, indicating that in the device of the present invention, the enhancement of voltage can more effectively separate hemicellulose.

[0117] Comparative Example 5

[0118] This comparative example is a comparison with Example 2. The same device as Example 2 is used, except that the voltage in step (1) is adjusted from 200V to 100V, while other operations and parameters remain unchanged.

[0119] Table 3. Preprocessing results of Example 2 and Comparative Example 5

[0120]

[0121] Table 3 shows that when the voltage is adjusted to 100V, the pretreatment temperature decreases and the electro-effect weakens, and the removal rate of hemicellulose in wheat straw decreases significantly. This indicates that the voltage in this invention should not be too low, and the voltage range should be above 200V.

[0122] Comparative Example 6

[0123] This comparative example is a comparison with Example 2. The same device as Example 2 is used, except that the voltage in step (2) is adjusted from 200V to 500V, while other operations and parameters remain unchanged.

[0124] Table 2. Preprocessing results of Example 2 and Comparative Example 6

[0125]

[0126]

[0127] As can be seen from Table 2, when the voltage is adjusted to 500V, although the removal rate of lignin in wheat straw is improved, the content of cellulose and hemicellulose decreases. This may be because cellulose and hemicellulose undergo partial degradation under high thermal and electrical effects. This indicates that the voltage in this invention cannot be too high. Therefore, in the device of this invention, the voltage range is between 200V and 800V and is adjusted according to the volume of the liquid.

[0128] Comparative Example 7

[0129] This comparative example is a comparison with Example 2. The same device as Example 2 is used, except that the voltage in step (2) is adjusted from 200V to 100V, while other operations and parameters remain unchanged.

[0130] Table 3. Preprocessing results of Example 2 and Comparative Example 7

[0131]

[0132] Table 3 shows that when the voltage is adjusted to 100V, the removal rate of lignin in wheat straw decreases, and the content of cellulose and hemicellulose decreases significantly. This is because the lower thermal effect and weaker electrical effect have a poorer effect on the removal of lignin. This indicates that the voltage in this invention should not be too low and should be adjusted according to the volume of the liquid.

[0133] It should be understood that the above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for achieving complete component separation of lignocellulose and improving enzymatic hydrolysis saccharification efficiency, characterized in that, The method uses an apparatus to achieve complete separation of lignocellulose components and improve enzymatic hydrolysis and saccharification efficiency. The apparatus consists of an electrothermal reaction unit, a pumping device, a stirring device, a power supply device, and a cooling device. The electrothermal reaction unit consists of a reaction tube, a magnetic core, a water-cooled plate, and an excitation coil; The magnetic core is a ring-shaped plate-shaped magnetic conductive material with a hole in the middle; the water-cooling plate is a ring-shaped plate-shaped metal material with a hole in the middle, which is placed alternately with the magnetic core; cooling pipes are embedded in the outer edge of the water-cooling plate to allow coolant to circulate; The water-cooled plate is connected to the cooling device via a cooling pipe; the cooling device is used to cool the coolant in the cooling pipe. The reaction tube passes through the middle hole of the magnetic core and the water-cooling plate and is wound around the magnetic core and the water-cooling plate; the inlet end of the reaction tube is located at the bottom end of the electrothermal reaction unit and is connected to the pumping device; the outlet end of the reaction tube is located at the top end of the electrothermal reaction unit and is connected to the stirring device through a pipe. The excitation coil is wound around the magnetic core and connected to a power supply device; the power supply device is used to provide excitation voltage, so that the magnetic core generates a time-varying magnetic field as an excitation source, and spontaneously induces voltage and current inside the reaction tube. The stirring device and the pumping device are connected by a pipeline, and the pipeline of the pumping device contacts the bottom of the container in the stirring device to ensure the pumping of the solution. The method specifically includes the following steps: (1) Wash the wood fiber raw material to remove the surface ash, then immerse it in an organic solvent for decolorization, then dry and crush it; (2) The pulverized wood fiber raw material and dilute acid solution in step (1) are placed into the stirring device, and the stirring is turned on to mix. After the mixture is evenly mixed, the pumping device is turned on to send the mixture into the reaction tube, and the power supply and cooling device are turned on to carry out the reaction. (3) After the reaction in step (2) is completed, the reaction mixture is subjected to solid-liquid separation. The obtained solid is washed until it is electrically neutral and dried to obtain a dry solid residue. The supernatant obtained by separation is hydrolyzed and purified to obtain crude xylose solid. (4) Place the dried solid residue from step (3) and the dilute alkaline solution into the above-mentioned stirring device, turn on the stirring to mix, and after the mixture is evenly mixed, turn on the pumping device to send the mixture into the reaction tube, turn on the power supply and cooling device to carry out the reaction. (5) After the reaction in step (4) is completed, solid-liquid separation is performed. The obtained solid is washed until it is electrically neutral, dried, and dried solid residue is obtained. The supernatant obtained is adjusted to pH 1-3 with acid solution and filtered to obtain solid components, which is lignin. (6) Mix the dried solid residue from step (5) with acetate buffer solution and add cellulase to perform enzymatic hydrolysis to obtain glucose; In step (2), the reaction temperature is 90-100℃ and the processing time is 3-7 h; the power supply parameters are set as follows: voltage 200-800 V, current 5-10 A, power 1-8 KW; the ratio of the voltage of the power supply to the diameter of the reaction tube is 200-250V : 10mm. In step (4), the reaction temperature is 50-90℃ and the processing time is 3-7 h; the power supply parameters are set as follows: voltage 200-800 V, current 5-10 A, power 1-8 KW; the ratio of the voltage of the power supply to the diameter of the reaction tube is 200-250V: 10mm.

2. The method according to claim 1, characterized in that, The lignocellulose raw materials mentioned in step (1) include straw and wood chips; the straw includes wheat straw and corn straw; the wood chips include poplar wood chips, eucalyptus wood chips, sugarcane bagasse, and bamboo powder.

3. The method according to claim 1, characterized in that, In step (2), the dilute acid solution includes one or more of dilute sulfuric acid and dilute hydrochloric acid; the concentration of the dilute acid solution is 0.5%-3%; and the mass-volume ratio of the pulverized wood fiber raw material to the dilute acid solution is 1g : 10-50mL.

4. The method according to claim 1, characterized in that, In step (2), after the power supply is turned on, the magnetic field strength of the magnetic core is 0.5-2T.

5. The method according to claim 1, characterized in that, In step (4), the dilute alkaline solution includes one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, sodium bicarbonate, and ammonia water; the concentration of the dilute alkaline solution is 0.5%-3%; and the mass-volume ratio of the dried solid residue to the dilute alkaline solution is 1g : 10-50mL.

6. The method according to claim 1, characterized in that, In step (4), after the power supply is turned on, the magnetic field strength of the magnetic core is 0.5-2T.

7. The method according to claim 1, characterized in that, In step (6), the acetate in the acetate buffer solution includes one or more of sodium acetate, potassium acetate, and ammonium acetate; the concentration of acetate in the acetate buffer solution is 0.01-0.1 mol / L; and the mass-volume ratio of the dried solid residue to the acetate buffer solution is 1 g : 30~70 mL.

8. The method according to claim 1, characterized in that, In step (6), the amount of cellulase added is 10-30 FPU / g substrate; the conditions for enzymatic hydrolysis are temperature 40-55℃, rotation speed 100-150 rpm, and time 48-72 h.

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