A method for ultrasonic wave combined sodium sulfite pretreatment of sargassum biomass

Abstract

The application discloses a method for pretreating Sargassum biomass by ultrasonic waves combined with sodium sulfite, which uses ultrasonic waves combined with sodium sulfite solution to pretreat Sargassum biomass raw materials; when the ultrasonic waves propagate in the biomass, high-intensity acoustic vibrations are generated, which can cause collisions and friction between the biomass particles, thereby breaking the cell wall and cellulose structure, and being beneficial to the sodium sulfite group to attack the aliphatic side chain of lignin and replace the hydroxyl functional group. The pretreatment of the biomass by the sodium sulfite can remove the lignin and hemicellulose in the Sargassum biomass, and at the same time, make the biomass structure become more porous and loose, reduce the mechanical strength, and increase the accessibility of cellulase. High-concentration fermentable sugar is obtained through the hydrolysis of cellulose-decomposing enzymes. In addition, a buffer solution is selected for the enzymolysis process, because it has better biocompatibility, reduces the potential toxicity of the system to the enzyme, and at the same time, as an organic acid, is easy to biodegrade and has little influence on the environment.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of resource utilization of Sargassum biomass cellulose, and relates to a method for pretreating Sargassum biomass by ultrasonic waves combined with sodium sulfite. BACKGROUND

[0002] In recent years, the frequency of large-scale Sargassum blooms (also known as 'golden tide') has significantly increased, causing great harm to local ecosystems, kelp cultivation, fisheries, tourism, and local biodiversity. The high salt and heavy metal content of invasive Sargassum makes it difficult to use in food additives and limits its industrial applications such as fertilizer and feed production. Despite the many obstacles, Sargassum can be converted into biofuels or other high-value compounds through biological processes, thanks to its rich carbohydrate, protein, and lipid content. The cellulose contained in Sargassum can be utilized by cellulases, a group of enzymes that mainly includes endoglucanases, exoglucanases, and beta-glucosidases. Cellulases rely on the synergistic action between enzymes to ultimately convert cellulose into glucose for fermentation by fermenting bacteria to produce bioethanol. The cellulose content in raw Sargassum is not high, so it is necessary to increase the cellulose content in Sargassum through pretreatment to increase the yield of enzymatic glucose and thus affect the fermentation of ethanol.

[0003] Currently, the pretreatment methods for biofuels mainly include four categories: chemical methods, physical methods, combined physical-chemical methods, and biological methods. The chemical methods mainly include dilute acid and dilute alkali treatment; the physical methods mainly include ultrasonic waves and microwaves; the combined physical-chemical methods mainly include ammonia fiber explosion and hydrothermal pretreatment; and the biological methods include fungal and bacterial fermentation. These methods have good performance in treating traditional lignocellulose, but still have problems such as equipment corrosion, low efficiency, and environmental pollution. When treating seaweed biomass, many methods are even more difficult to apply. SUMMARY

[0004] The present application aims to solve the problem of low efficiency and environmental pollution in the prior art when increasing the cellulose content in Sargassum through existing pretreatment methods, and provides a method for pretreating Sargassum biomass by ultrasonic waves combined with sodium sulfite.

[0005] To achieve the above-mentioned purpose, the following technical solutions are adopted in the present application:

[0006] The method for pretreating Sargassum biomass by ultrasonic waves combined with sodium sulfite proposed in the present application comprises the following steps:

[0007] Mixing Sargassum powder with water, adding sodium sulfite to obtain a dispersion solution;

[0008] The dispersed solution is subjected to ultrasonic and oscillation treatment, and the filter residue is obtained by centrifugal filtration after the reaction is completed;

[0009] The filter residue is subjected to filtration with deionized water until the filtrate is neutral, and the pretreated sargassum thunbergii raw material is obtained by drying the filter residue;

[0010] The pretreated sargassum thunbergii raw material is placed in a buffer solution, and a catalyst is added for reaction to obtain supernatant glucose, and the pretreatment of sargassum thunbergii biomass is realized.

[0011] Preferably, the obtained sargassum thunbergii powder is dried for 4h-8h, the drying temperature is 100℃-120℃, and the sargassum thunbergii powder is sieved after grinding; the storage and transportation temperature of the sargassum thunbergii powder is 0℃-4℃.

[0012] Preferably, the solid-liquid ratio of the sargassum thunbergii powder and water is 1:20-1:100, the amount of sodium sulfite is 0.02g-1g, and the concentration of sodium sulfite is 0.1wt%-1.0wt%.

[0013] Preferably, the dispersed solution is subjected to ultrasonic and oscillation treatment, specifically: ultrasonic treatment at a power of 200W-400W for 20min-40min, and the ultrasonic temperature is 20℃-40℃.

[0014] Preferably, after the ultrasonic treatment, the sargassum thunbergii is further treated in a shaking bed, specifically: oscillation at 40℃-60℃ and 150rpm-250rpm for 1h-8h.

[0015] Preferably, when the centrifugal treatment is performed, the centrifuge speed is 5000rpm-8000rpm, and the centrifugal time is 2min-4min.

[0016] Preferably, the pretreated sargassum thunbergii raw material is placed in a buffer solution, and the buffer solution is a sodium citrate buffer solution.

[0017] Preferably, the concentration of the buffer solution is 0.05M / L-0.1M / L, the pH value of the buffer solution is 4.5-5.0, and the amount of the buffer solution is 50mL-100mL.

[0018] Preferably, the catalyst is cellulase, and the amount of cellulase is 30FPU / g-60FPU / g; the enzymolysis time is 24h-72h.

[0019] Preferably, the enzymolysis is performed in a shaking bed, and the temperature range is 45℃-60℃, and the rotation speed is set to 100rpm-150rpm.

[0020] Compared with the prior art, the present application has the following beneficial effects:

[0021] The present application provides a method for pretreating Sargassum biomass by ultrasonic combined with sodium sulfite, sodium sulfite has been used as a reducing agent in wastewater treatment to eliminate organic pollutants. In the process of sulfite pretreatment, sulfite groups attack the aliphatic side chains of lignin and replace the hydroxyl functional groups, most of the lignin is sulfonated and has higher hydrophilicity, which helps cellulase to approach the glucan chain and improves the efficiency of cellulase due to the reduction of ineffective binding and steric hindrance. Using ultrasonic combined with sodium sulfite solution to pretreat Sargassum biomass raw materials, when ultrasonic propagates in biomass, it will produce high-intensity acoustic vibration, which will cause collision and friction between biomass particles, thereby breaking the cell wall and cellulose structure, which is conducive to the attack of sulfite groups on the aliphatic side chains of lignin and the replacement of hydroxyl functional groups. Pretreatment of biomass with sodium sulfite can remove lignin and hemicellulose in Sargassum biomass while making the biomass structure more porous and loose, reducing mechanical strength and increasing cellulase accessibility. The main goal of pretreatment is to reduce the crystallinity of cellulose, decompose hemicellulose, and remove lignin. In this way, high-concentration fermentable sugar can be obtained through the hydrolysis of cellulose-degrading enzymes. In addition, buffer solution is selected for enzymolysis process because it has better biocompatibility, reduces the potential toxicity of the system to enzymes, and as an organic acid, it is easily biodegradable and has little impact on the environment. Pretreatment of Sargassum with sodium sulfite at room temperature reduces environmental pollution caused by traditional acid-base pretreatment and obtains more cellulose retention rate. Therefore, the method for pretreating Sargassum biomass proposed by the present application can solve the problems existing in the prior art. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0023] Figure 1 The schematic diagram of the method for pretreating Sargassum biomass raw materials by ultrasonic combined with sodium sulfite of the present application.

[0024] Figure 2 The scanning electron microscope images of Sargassum powder after different treatments ((a) untreated raw material; (b) raw material after ultrasonic treatment; (c) raw material after sodium sulfite treatment only; (d) raw material after ultrasonic and sodium sulfite treatment).

[0025] Figure 3 The Fourier infrared spectrum of Sargassum powder after different treatments of the present application. DETAILED DESCRIPTION

[0026] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will be combined with the accompanying drawings of the embodiments of the present application to make a clear and complete description of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the accompanying drawings can be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative labor are within the scope of protection of the present application.

[0028] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0029] In the description of the embodiments of the present application, it should be noted that, if the orientation or position relationship indicated by the terms "upper", "lower", "horizontal", "inner" and the like is based on the orientation or position relationship shown in the drawings, or is the orientation or position relationship when the product of the present application is usually placed, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, therefore, it cannot be understood as a limitation on the present application. In addition, the terms "first", "second" and the like are only used for differentiation in description, and cannot be understood as indicating or implying relative importance.

[0030] The present application will be further described in detail below in combination with the accompanying drawings:

[0031] The present application proposes a method for pretreating Sargassum biomass by ultrasonic waves combined with sodium sulfite, which comprises the following steps:

[0032] Step 1, after mixing Sargassum powder with water, adding sodium sulfite to obtain a dispersion solution;

[0033] The obtained Sargassum powder is dried for 4-8 hours at a drying temperature of 100-120℃, and then ground and sieved after drying; the storage and transportation temperature of the Sargassum powder is 0-4℃.

[0034] The solid-liquid ratio of Sargassum powder to water is 1:20-1:100, the amount of sodium sulfite is 0.02-1g, and the concentration of sodium sulfite is 0.1wt%-1.0wt%.

[0035] Step 2, ultrasonic and oscillation treatment is carried out on the dispersion solution, and the filter residue is obtained by centrifugal filtration after the reaction is completed;

[0036] The ultrasonic and oscillation treatment on the dispersion solution is specifically: ultrasonic treatment for 20-40 min under the power of 200-400 W, and the ultrasonic temperature is 20-40℃.

[0037] After the ultrasonic treatment, the Sargassum continues to be treated in a shaking bed, specifically: oscillation for 1-8 h at 40-60℃ and 150-250 rpm.

[0038] When the centrifugal treatment is carried out, the centrifugal speed is 5000-8000 rpm, and the centrifugal time is 2-4 min.

[0039] Step 3, the filter residue is filtered with deionized water until the filtrate is neutral, and the pretreated Sargassum raw material is obtained by drying the filter residue.

[0040] Step 4, the pretreated Sargassum raw material is put into a buffer solution, and a catalyst is added for reaction to obtain supernatant glucose, so as to realize the pretreatment of Sargassum biomass.

[0041] The buffer solution is a sodium citrate buffer solution. The buffer solution is used in an amount of 0.05-0.1 M / L, and the pH value of the buffer solution is 4.5-5.0.

[0042] The catalyst is cellulase, and the amount of cellulase used is 30-60 FPU / g; the enzymolysis time is 24-72 h. The enzymolysis is carried out in a shaking bed, and the temperature range is 45-60℃, and the rotation speed is set to 100-150 rpm.

[0043] The method is described in detail as follows:

[0044] Step 1, fresh salvaged Sargassum is used as raw material after being dried and ground into powder, and the mass / volume ratio of the raw material to water is 1 g:(20-100) mL, i.e. the solid-liquid ratio is 1:20-1:100, which is placed in a conical flask. Then 0.02-1 g of sodium sulfite is added to make the concentration 0.1-1.0 wt%, and then the solution is shaken and dispersed to obtain a dispersion solution.

[0045] The fresh salvaged Sargassum is salted and stored and transported at low temperature, the storage and transportation temperature is 0-4℃, the Sargassum is dried in an oven for 4-8 hours, the oven temperature is 100-120℃, and the Sargassum is ground after drying and sieved through an 80 mesh sieve.

[0046] Step 2, the prepared dispersion solution is placed in an ultrasonic device, and is ultrasonically treated at a fixed frequency of 40 kHz and a power of 50%-100% of the maximum power, i.e. 200-400 W, at 20-40°C for 20-40 min. After the ultrasonic treatment, the solution is placed in a shaking table for reaction, specifically, the solution is shaken at 30-60°C and 150-250 rpm for 1-8 h. After the reaction, the solution is centrifuged and filtered to separate the solid and the liquid, and the filter residue is obtained. During the centrifugation, the centrifuge is rotated at a speed of 5000-8000 rpm, i.e. the relative centrifugal force is 2569-6577 xg, and the centrifugation time is 2-4 min.

[0047] Step 3, the filter residue is repeatedly washed with deionized water until the filtrate is neutral, and the filter residue is completely dried at 90°C to obtain the raw material of sargassum prepared by pretreatment. The raw material of sargassum is subjected to the next step of detection and enzymatic hydrolysis.

[0048] Step 4, the raw material of sargassum prepared by pretreatment is placed in 50-100 mL of a sodium citrate buffer having a concentration of 0.05-0.1 M / L and a pH value of 4.5-5.0, and 30-60 FPU / g of cellulase is added for enzymatic hydrolysis for 24-72 h. The enzymatic hydrolysis is performed in a shaking table, and the temperature is set to be 45-60°C and the rotation speed is set to be 100-150 rpm.

[0049] The content of glucose in the supernatant after the enzymatic hydrolysis is detected by a biological sensor, and the contents of cellulose, hemicellulose and acid-insoluble substances in the sargassum biomass are measured by the standard method of the U.S. Department of Energy (NREL).

[0050] Example 1:

[0051] A method for pretreating sargassum biomass by ultrasonic wave combined with sodium sulfite, comprising the following steps:

[0052] (1) Freshly salvaged sargassum is stored and transported at 4°C, and the powder obtained by drying and grinding at 120°C is used as the raw material. The raw material is placed in a conical flask according to a mass-volume ratio of the raw material to water of 1 g: 50 mL, i.e. a solid-liquid ratio of 1:50. Then, 0.15 g of sodium sulfite is added to make the concentration of sodium sulfite 0.4 wt%, and the solution is shaken to disperse the raw material. The prepared dispersion solution is placed in an ultrasonic device, and is ultrasonically treated at a fixed frequency of 40 kHz and a power of 60% of the maximum power, i.e. 240 W, at 40°C for 30 min. After the ultrasonic treatment, the solution is placed in a shaking table and is reacted at 40°C and 200 rpm for 4 h. After the reaction, the solution is centrifuged (5000 rpm, 4 min) and filtered to separate the solid and the liquid, and the filter residue is obtained. The filter residue is repeatedly washed with deionized water until the filtrate is neutral, and the filter residue is completely dried at 90°C to obtain the raw material of sargassum prepared by pretreatment. The raw material of sargassum is subjected to the next step of detection and enzymatic hydrolysis.

[0053] (2) The raw material powder prepared in (1) was weighed and placed in 50 mL of citric acid-sodium citrate buffer (0.05 M, pH 4.5) and 30 FPU / g of cellulase was added for 72 h of enzymatic hydrolysis. The enzymatic hydrolysis was carried out in a shaker, and the temperature was set at 50°C and the rotation speed was set at 150 rpm.

[0054] Example 2:

[0055] A method for pretreating Sargassum biomass by ultrasonic waves combined with sodium sulfite, comprising the following steps:

[0056] (1) Freshly salvaged Sargassum was stored and transported at 0°C, and the powder after drying at 100°C for 4 h and grinding was used as the raw material. The raw material was placed in a conical flask according to a mass-volume ratio of the raw material to water of 1 g:20 mL, i.e., a solid-liquid ratio of 1:20. Then, 0.2 g of sodium sulfite was added to make the concentration 1 wt%, and the solution was shaken to disperse the raw material. The prepared dispersion solution was placed in an ultrasonic wave generating device at a temperature of 20°C, and ultrasonic waves were generated at a fixed frequency of 40 kHz at 100% of the maximum power, i.e., a power of 400 W, for 20 min. After the ultrasonic waves were generated, the solution was placed in a shaker at 30°C and 250 rpm for 6 h of reaction. After the reaction was completed, centrifugation (8000 rpm, 2 min) was performed, and suction filtration was performed to separate the solid and liquid. The filter residue was washed repeatedly with deionized water, suction filtered until the filtrate was neutral, and the filter residue was completely dried at 90°C to obtain the pretreated Sargassum raw material. The Sargassum raw material was subjected to the next step of detection and enzymatic hydrolysis.

[0057] (2) The raw material powder prepared in (1) was weighed and placed in 50 mL of citric acid-sodium citrate buffer (0.1 M, pH 5.0) and 60 FPU / g of cellulase was added for 24 h of enzymatic hydrolysis. The enzymatic hydrolysis was carried out in a shaker, and the temperature was set at 45°C and the rotation speed was set at 100 rpm.

[0058] Example 3:

[0059] A method for pretreating Sargassum biomass by ultrasonic waves combined with sodium sulfite, comprising the following steps:

[0060] (1) Freshly salvaged Sargassum 2℃ stored and transported, 110℃ 6h dried and ground powder as raw material, according to the mass volume ratio of raw material and water 1g:100mL, namely the solid-liquid ratio of 1:100, placed in a conical flask. Then add 0.1g sodium sulfite to make its concentration of 0.1wt%, then shake the solution evenly dispersed. The prepared dispersion solution was placed in an ultrasonic device with a temperature of 20℃, at a fixed frequency of 40kHz with a maximum power of 80%, namely 320W power ultrasonic 40min, after ultrasonic end again put into the shaker at 20℃, 150rpm reaction 8h. After the reaction, centrifugation (6000rpm, 2min) and suction filtration to separate the solid and liquid, the filter residue was washed repeatedly with deionized water and suction filtered until the filtrate was neutral. The filter residue was completely dried at 90℃ to obtain the pretreated Sargassum raw material, which was subjected to the next step of detection and enzymolysis.

[0061] (2) The raw material powder prepared in (1) was weighed and placed in 100mL citric acid-sodium citrate buffer (0.08M, pH4.8) and 45FPU / g cellulase was added for 48h enzymolysis. Enzymolysis was carried out in a shaker, the temperature was set at 55℃, and the rotation speed was set at 150rpm.

[0062] Example 4:

[0063] A method for pretreating Sargassum biomass by ultrasonic combined with sodium sulfite, comprising the following steps:

[0064] (1) Freshly salvaged Sargassum 4℃ stored and transported, 120℃ 5h dried and ground powder as raw material, according to the mass volume ratio of raw material and water 1g:50mL, namely the solid-liquid ratio of 1:50, placed in a conical flask. Then add 0.7g sodium sulfite to make its concentration of 0.7wt%, then shake the solution evenly dispersed. The prepared dispersion solution was placed in an ultrasonic device with a temperature of 30℃, at a fixed frequency of 40kHz with a maximum power of 70%, namely 280W power ultrasonic 40min, after ultrasonic end again put into the shaker at 50℃, 200rpm reaction 4h. After the reaction, centrifugation (5000rpm, 3min) and suction filtration to separate the solid and liquid, the filter residue was washed repeatedly with deionized water and suction filtered until the filtrate was neutral. The filter residue was completely dried at 90℃ to obtain the pretreated Sargassum raw material, which was subjected to the next step of detection and enzymolysis.

[0065] (2) The raw material powder prepared in (1) was weighed and placed in 75mL citric acid-sodium citrate buffer (0.1M, pH5.0) and 45FPU / g cellulase was added for 48h enzymolysis. Enzymolysis was carried out in a shaker, the temperature was set at 60℃, and the rotation speed was set at 100rpm.

[0066] Example 5:

[0067] A method for pretreating Sargassum biomass by ultrasonic wave combined with sodium sulfite, comprising the following steps:

[0068] (1) Freshly salvaged Sargassum was stored and transported at 4℃, and the powder obtained by drying and grinding at 100℃ for 8h was used as raw material. The raw material was placed in a conical flask according to a mass-volume ratio of raw material to water of 1g:80mL, i.e. a solid-liquid ratio of 1:80. Then 0.5g of sodium sulfite was added to make the concentration 0.5wt%, and the raw material in the solution was shaken and dispersed. The prepared dispersion solution was placed in an ultrasonic wave generating device at a temperature of 35℃, and ultrasonic wave was generated at a fixed frequency of 40kHz and a power of 200W (50% of the maximum power) for 30min. After the ultrasonic wave treatment, the solution was placed in a shaking table for reaction at 60℃ and 200rpm for 1h. After the reaction, centrifugation (7000rpm, 3min) was performed, and then suction filtration was performed to separate the solid and liquid. The filter residue was repeatedly washed with deionized water until the filtrate was neutral, and the filter residue was completely dried at 90℃ to obtain the pretreated Sargassum raw material. The Sargassum raw material was subjected to the next step of detection and enzymatic hydrolysis.

[0069] (2) The raw material powder prepared in (1) was weighed and placed in 100mL of citric acid-sodium citrate buffer (0.05M, pH4.5), and 30FPU / g of cellulase was added for 72h of enzymatic hydrolysis. The enzymatic hydrolysis was performed in a shaking table, and the temperature was set at 50℃ and the rotation speed was set at 100rpm.

[0070] Example 6:

[0071] A method for pretreating Sargassum biomass by ultrasonic wave combined with sodium sulfite, comprising the following steps:

[0072] (1) Freshly salvaged Sargassum was stored and transported at 0℃, and the powder obtained by drying and grinding at 110℃ for 4h was used as raw material. The raw material was placed in a conical flask according to a mass-volume ratio of raw material to water of 1g:100mL, i.e. a solid-liquid ratio of 1:100. Then 1g of sodium sulfite was added to make the concentration 1wt%, and the raw material in the solution was shaken and dispersed. The prepared dispersion solution was placed in an ultrasonic wave generating device at a temperature of 40℃, and ultrasonic wave was generated at a fixed frequency of 40kHz and a power of 240W (60% of the maximum power) for 40min. After the ultrasonic wave treatment, the solution was placed in a shaking table for reaction at 20℃ and 150rpm for 8h. After the reaction, centrifugation (7000rpm, 3min) was performed, and then suction filtration was performed to separate the solid and liquid. The filter residue was repeatedly washed with deionized water until the filtrate was neutral, and the filter residue was completely dried at 90℃ to obtain the pretreated Sargassum raw material. The Sargassum raw material was subjected to the next step of detection and enzymatic hydrolysis.

[0073] (2) The raw material powder prepared in (1) was weighed and placed in 75 mL of citric acid-sodium citrate buffer (0.05 M, pH 4.5) and 30 FPU / g of cellulase was added for enzymatic hydrolysis for 72 h. The enzymatic hydrolysis was carried out in a shaker, and the temperature was set at 50°C and the rotation speed was set at 100 rpm.

[0074] Example 7:

[0075] A method for pretreating Sargassum biomass by ultrasonic wave combined with sodium sulfite, comprising the following steps:

[0076] (1) Freshly salvaged Sargassum was stored and transported at 4°C, and the powder after drying at 100°C for 8 h was ground as the raw material. The raw material was placed in a conical flask according to the mass-volume ratio of raw material to water of 1 g: 50 mL, i.e. the solid-liquid ratio of 1:50. Then 0.25 g of sodium sulfite was added to make the concentration of 0.5 wt%, and the raw material in the solution was shaken and dispersed. The prepared dispersion solution was placed in an ultrasonic wave generating device at a temperature of 30°C, and ultrasonic waves were generated at a fixed frequency of 40 kHz at 100% of the maximum power, i.e. 400 W power, for 20 min. After the ultrasonic wave treatment, the solution was placed in a shaker at 50°C and 200 rpm for 6 h. After the reaction, centrifugation (5000 rpm, 4 min) was performed, and then filtration was performed to separate the solid and liquid. The filter residue was washed repeatedly with deionized water until the filtrate was neutral, and the filter residue was completely dried at 90°C to obtain the pretreated Sargassum raw material. The Sargassum raw material was subjected to the next step of detection and enzymatic hydrolysis.

[0077] (2) The raw material powder prepared in (1) was weighed and placed in 100 mL of citric acid-sodium citrate buffer (0.1 M, pH 5.0) and 30 FPU / g of cellulase was added for enzymatic hydrolysis for 48 h. The enzymatic hydrolysis was carried out in a shaker, and the temperature was set at 50°C and the rotation speed was set at 100 rpm.

[0078] Example 8:

[0079] A method for pretreating Sargassum biomass by ultrasonic wave combined with sodium sulfite, comprising the following steps:

[0080] (1) Freshly salvaged Sargassum 2℃ preservation and transportation, 120℃ 5h drying after grinding powder as raw material, according to the mass volume ratio of raw material and water is 1g:20mL, namely the solid-liquid ratio is 1:20, placed in the conical flask. Add 0.02g sodium sulfite to make its concentration is 0.1wt%, then shake the solution evenly dispersed. The prepared dispersion solution is placed in the ultrasonic device, the temperature is 40℃, under the fixed frequency of 40kHz, with the maximum power of 80%, namely 320W power ultrasonic 40min, after ultrasonic end again put into the shaking table at 40℃, 250rpm reaction 4h. After reaction, centrifugation (7000rpm, 2min) after suction filtration to make solid-liquid separation, get the filter residue using deionized water repeatedly washing suction filtration until the filtrate is neutral, 90℃ completely drying the filter residue as pretreatment prepared Sargassum raw material, Sargassum raw material for the next step of detection and enzymolysis.

[0081] (2) The raw material powder prepared in (1) is weighed and placed in 80mL citric acid-sodium citrate buffer (0.08M, pH 4.8) and 45FPU / g cellulase is added for 36h enzymolysis. Enzymolysis needs to be carried out in a shaking table, the temperature is set at 50℃, and the rotation speed is set at 100rpm.

[0082] Example 9:

[0083] A method for pretreating Sargassum biomass by ultrasonic combined with sodium sulfite, comprising the following steps:

[0084] (1) Freshly salvaged Sargassum 0℃ preservation and transportation, 100℃ 7h drying after grinding powder as raw material, according to the mass volume ratio of raw material and water is 1g:80mL, namely the solid-liquid ratio is 1:80, placed in the conical flask. Add 0.8g sodium sulfite to make its concentration is 1wt%, then shake the solution evenly dispersed. The prepared dispersion solution is placed in the ultrasonic device, the temperature is 40℃, under the fixed frequency of 40kHz, with the maximum power of 60%, namely 240W power ultrasonic 30min, after ultrasonic end again put into the shaking table at 30℃, 200rpm reaction 6h. After reaction, centrifugation (6000rpm, 4min) after suction filtration to make solid-liquid separation, get the filter residue using deionized water repeatedly washing suction filtration until the filtrate is neutral, 90℃ completely drying the filter residue as pretreatment prepared Sargassum raw material, Sargassum raw material for the next step of detection and enzymolysis.

[0085] (2) The raw material powder prepared in (1) is weighed and placed in 50mL citric acid-sodium citrate buffer (0.1M, pH 4.5) and 60FPU / g cellulase is added for 48h enzymolysis. Enzymolysis needs to be carried out in a shaking table, the temperature is set at 50℃, and the rotation speed is set at 100rpm.

[0086] Example 10:

[0087] A method for pretreating sargassum biomass by ultrasonic wave combined with sodium sulfite, comprising the following steps:

[0088] (1) Freshly salvaged sargassum was stored and transported at 4℃, and the powder after drying at 105℃ for 6h was used as raw material. The raw material was placed in a conical flask according to the mass-volume ratio of raw material to water of 1g:30mL, i.e. the solid-liquid ratio of 1:30. Then 0.15g of sodium sulfite was added to make the concentration 0.5wt%, and the raw material was shaken and dispersed in the solution. The prepared dispersion solution was placed in an ultrasonic wave generating device at a temperature of 30℃, and ultrasonic wave was generated at a fixed frequency of 40kHz at 60% of the maximum power, i.e. 240W power, for 30min. After the ultrasonic wave treatment, the solution was placed in a shaking table at 20℃ and 250rpm for 8h of reaction. After the reaction, centrifugation (8000rpm, 2min) was performed, and then filtration was performed to separate the solid and liquid, so that the filter residue was obtained. The filter residue was repeatedly washed with deionized water and filtered until the filtrate was neutral. The filter residue was completely dried at 90℃ to obtain the pretreated sargassum raw material. The sargassum raw material was subjected to the next step of detection and enzymatic hydrolysis.

[0089] (2) The raw material powder prepared in (1) was weighed and placed in 50mL of citric acid-sodium citrate buffer (0.05M, pH 5), and 45FPU / g of cellulase was added for 72h of enzymatic hydrolysis. The enzymatic hydrolysis was performed in a shaking table, and the temperature was set at 50℃ and the rotation speed was set at 100rpm.

[0090] Comparative test

[0091] Experimental group 1: The salted sargassum was fully soaked and cleaned, dried in an oven at 110℃, ground, and the sargassum powder after passing through an 80 mesh sieve was used as raw material without any treatment;

[0092] Experimental group 2: 50mL of deionized water was added to a conical flask, 1g of the sargassum powder prepared in experimental group 1 was taken, so that the solid-liquid ratio was 1:50, and a glass rod was used to stir to make the sargassum powder uniformly dispersed in the solution. The prepared solution was placed in an ultrasonic cleaner and ultrasonic wave was generated at a power of 240W for 30min.

[0093] Experimental group 3: 50mL of deionized water was added to a conical flask, 1g of the sargassum powder prepared in experimental group 1 was taken, so that the solid-liquid ratio was 1:50, and 0.2g of sodium sulfite was added to make the concentration 0.4wt%. A glass rod was used to stir to make the sargassum powder uniformly dispersed in the solution. The prepared solution was placed in a constant temperature shaking incubator for 4h of pretreatment at 30℃, and the rotation speed of the constant temperature shaking incubator was 200rpm.

[0094] The raw material powder prepared in experimental groups 1, 2 and 3 was placed in 50mL of citric acid-sodium citrate buffer and 30FPU / g of cellulase was added for 72h of enzymatic hydrolysis. The enzymatic hydrolysis was performed in a shaking table, and the temperature was set at 50℃ and the rotation speed was set at 150rpm.

[0095] The glucose content of the supernatant after enzymatic hydrolysis in experimental groups 1, 2, and 3 was detected using a biosensor. The content of cellulose, hemicellulose, and acid-insoluble substances in Sargassum biomass powder was determined using the standard method of the U.S. Department of Energy (NREL).

[0096] Analysis of the products obtained from the above 7 sets of experiments yielded the following results:

[0097] Table 1. Composition changes and test results of samples under different pretreatment conditions.

[0098]

[0099] As shown in Table 1, the components of Sargassum underwent significant changes before and after pretreatment. After pretreatment, the cellulose content of the samples increased significantly, while the contents of hemicellulose and acid-insoluble substances decreased. Among them, Example 1 yielded the best results, retaining 23.88% of the cellulose content and achieving an enzymatic glucose yield of 107.75 mg / g.

[0100] from Figure 2 As can be seen in (a), the untreated Sargassum biomass has a dense and smooth structure, almost completely obscuring its internal structure, which makes it difficult for enzymes to enter. Figure 2 (b) shows that the Sargassum powder, after only ultrasonic pretreatment, still retains an intact and dense surface structure without significant damage. Figure 2 Image (c) shows the biomass treated with sodium sulfite. After treatment, the biomass structure of Sargassum was destroyed, with numerous grooves appearing on the surface and many fibrous fragments peeling off, exhibiting a more disordered arrangement, changing from a compact and intact state to a loose and porous one. Figure 2 (d) in the figure represents Sargassum powder treated with sodium sulfite under ultrasound-assisted conditions. Figure 2 Compared to the potassium permanganate pretreatment with ultrasonic assistance, (c) showed more significant damage, with more pores appearing on the powder surface due to the dissolution of components.

[0101] exist Figure 3 Middle, 3400cm -1 The absorption peak at 2927 cm⁻¹ is associated with the OH stretching vibrations of phenolic, carboxyl, and alcohol groups. -1 The absorption peak at 1637 cm⁻¹ represents the CH stretching vibration, indicating the presence of methyl and methylene groups, further confirming the presence of lignin. Meanwhile, the absorption peak at 1637 cm⁻¹... -1 The strong peak at 1514 cm⁻¹ is caused by the stretching vibration of the benzene ring, which is also a marker of lignin. -1 This is a characteristic peak of lignin, indicating the vibration of the lignin aromatic skeleton, 1425 cm⁻¹. -1 The absorption peak at 1166 cm⁻¹ is due to the C–H stretching vibration of lignin. -1The decrease of the observed intensity, the syringyl, guaiacyl and hydroxyphenyl groups in surface lignin were removed, 831 cm -1 The absorption peak at 1028 cm -1 The absorption peak at 1028 cm -1 The absorption peak at 1028 cm -1 From the figure, it can be clearly seen that after treatment, the lignin related peaks in the sargassum powder are obviously weakened, indicating that the content of lignin has significantly decreased.

[0102] The above only for the preferred embodiments of the present application, and is not intended to limit the present application, for those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application, should be included in the protection scope of the present application.

Claims

1. A method for pretreating Sargassum biomass using ultrasound combined with sodium sulfite, characterized in that, Includes the following steps: After mixing Sargassum powder with water, sodium sulfite is added to obtain a dispersion solution; The dispersion solution was subjected to ultrasonic and oscillation treatment, and after the reaction was completed, it was centrifuged and filtered to obtain the filter residue. The filter residue was filtered with deionized water until the filtrate was neutral, and the filter residue was dried to obtain pretreated Sargassum raw material. The pretreated Sargassum raw material is placed in a buffer solution, and then a catalyst is added to react and obtain glucose in the supernatant, thus achieving the pretreatment of Sargassum biomass. The solid-liquid ratio of Sargassum powder to water is 1:20-1:100, the amount of sodium sulfite is 0.02 g-1 g, and the concentration of sodium sulfite is 0.1 wt%-1.0 wt%.

2. The method for pretreating Sargassum biomass using ultrasound combined with sodium sulfite according to claim 1, characterized in that, The obtained Sargassum powder was dried for 4-8 hours at a temperature of 100-120℃, then ground and sieved. The Sargassum powder was stored and transported at a temperature of 0-4℃.

3. The method for pretreating Sargassum biomass using ultrasound combined with sodium sulfite according to claim 1, characterized in that, The ultrasonic and oscillation treatment of the dispersion solution is specifically performed by ultrasonic treatment at a power of 200 W-400 W for 20 min-40 min and an ultrasonic temperature of 20℃-40℃.

4. The method for pretreating Sargassum biomass using ultrasound combined with sodium sulfite according to claim 1, characterized in that, After ultrasonic treatment, the Sargassum was further treated in a shaker, specifically by shaking at 40℃-60℃ and 150 rpm-250 rpm for 1 h-8 h.

5. The method for pretreating Sargassum biomass using ultrasound combined with sodium sulfite according to claim 1, characterized in that, When performing centrifugation, the centrifuge speed is 5000 rpm-8000 rpm, and the centrifugation time is 2 min-4 min.

6. The method for pretreating Sargassum biomass using ultrasound combined with sodium sulfite according to claim 1, characterized in that, The pretreated Sargassum raw material is placed in a buffer solution, which is sodium citrate buffer solution.

7. The method for pretreating Sargassum biomass using ultrasound combined with sodium sulfite according to claim 1, characterized in that, The buffer concentration range is 0.05 M / L-0.1 M / L, the pH value of the buffer is 4.5-5.0, and the buffer volume is 50 mL-100 mL.

8. The method for pretreating Sargassum biomass using ultrasound combined with sodium sulfite according to claim 1, characterized in that, The catalyst is cellulase, and the amount of cellulase used is 30 FPU / g to 60 FPU / g; the enzymatic hydrolysis time is 24 h to 72 h.

9. The method for pretreating Sargassum biomass using ultrasound combined with sodium sulfite according to claim 8, characterized in that, Enzymatic hydrolysis was carried out in a shaker at a temperature range of 45℃-60℃ and a rotation speed of 100 rpm-150 rpm.

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