A method for ultrasonic-assisted low-concentration potassium permanganate pretreatment of sargassum biomass

Abstract

The application discloses a method for ultrasonic-assisted low-concentration potassium permanganate pretreatment of Sargassum biomass, and the method can effectively remove impurities and harmful substances in Sargassum and improve the efficiency of subsequent treatment by adding Sargassum powder into deionized water and adding potassium permanganate. Ultrasonic treatment and oscillation treatment are helpful to the uniformity of solution dispersion, the subsequent centrifugation and filtration steps, and the reduction of material loss. Therefore, the Sargassum biomass raw material is pretreated by using ultrasonic-assisted low-concentration potassium permanganate solution at room temperature, the severe shearing force and cavitation phenomenon generated by ultrasonic high-frequency vibration are used to enhance the oxidative decomposition of lignocellulose by the potassium permanganate solution, the lignin and hemicellulose in the Sargassum biomass are removed, and the structure of the Sargassum biomass becomes more porous and loose, the mechanical strength is reduced, and the accessibility of cellulase is increased. Therefore, the method can improve the cellulose recovery rate and is environment-friendly and pollution-free after the Sargassum is pretreated.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of seaweed biomass cellulose resource utilization, and relates to a method for ultrasonic-assisted low-concentration potassium permanganate pretreatment of sargassum biomass. BACKGROUND

[0002] The large-scale exploitation and consumption of non-renewable energy sources such as coal, oil and natural gas have provided impetus for industrialization, but have also brought serious environmental challenges. In this context, biomass energy, especially marine algae, has gradually become a research and development hotspot due to its rapid reproduction ability, high biomass output and non-arable land occupation characteristics.

[0003] The development of biomass energy mainly relies on enzymatic fermentation technology, which removes lignin and hemicellulose in biomass through pretreatment methods to destroy its rigid structure, thereby improving the enzymatic hydrolysis efficiency. However, existing pretreatment technologies, although have made certain progress in improving hydrolysis efficiency, still face many challenges. For example, chemical pretreatment methods often involve the use of dilute acid or alkali solution, which not only has corrosion to equipment, but also may cause environmental pollution problems. Physical pretreatment technologies such as ultrasound and microwave, although avoid the use of chemical reagents, have high energy consumption and expensive equipment costs. Combined physical and chemical methods and biological methods, although to some extent reduce the use of chemical reagents, still have problems such as complex operation and high cost. In recent years, marine algae have gradually been recognized as the potential of the third generation of biofuels, and their pretreatment technology has become a research focus. Common pretreatment methods include chemical methods, physical methods, combined physical and chemical methods and biological methods. Chemical methods mainly use dilute acid or alkali solution to treat biomass, and physical methods achieve the destruction of biomass structure through ultrasound, microwave and other technologies. Combined physical and chemical methods such as ammonia fiber explosion and hydrothermal pretreatment, and biological methods such as fungal and bacterial fermentation, all show potential in improving enzymatic hydrolysis efficiency. However, these methods still have many limitations in practical application, such as equipment corrosion, environmental pollution, high cost, etc., which seriously restrict their application on an industrial scale. SUMMARY

[0004] The purpose of the present application is to solve the problem of low cellulose recovery rate and environmental pollution caused by the method of pretreating sargassum biomass in the prior art, and to provide a method for ultrasonic-assisted low-concentration potassium permanganate pretreatment of sargassum biomass.

[0005] To achieve the above purpose, the technical scheme is adopted as follows:

[0006] The method for ultrasonic-assisted low-concentration potassium permanganate pretreatment of sargassum biomass provided by the present application comprises the following steps:

[0007] Add Sargassum powder to deionized water, then add potassium permanganate and stir to obtain the prepared solution.

[0008] The prepared solution was subjected to ultrasonic treatment and oscillation treatment in sequence to obtain a dispersion solution;

[0009] Centrifuge the dispersion solution and then filter the supernatant until the extracted liquid is neutral. Dry the filter residue to constant weight to obtain pretreated Sargassum biomass raw material.

[0010] The pretreated Sargassum biomass raw material was poured into a buffer solution and a catalyst was added to react, resulting in glucose supernatant, thus achieving the pretreatment of Sargassum biomass.

[0011] Preferably, the step of obtaining Sargassum powder is as follows:

[0012] Salted Sargassum was soaked and washed, then completely dried, ground and sieved, and stored at room temperature away from light to obtain Sargassum powder; the drying temperature was 100℃-120℃, and the drying time was 4h-8h.

[0013] Preferably, the ratio of Sargassum powder, deionized water, and potassium permanganate is 0.5g-2.5g: 50mL-100mL: 0.05g-1g; and the concentration of potassium permanganate is in the range of 0.1wt%-1wt%.

[0014] Preferably, when performing ultrasonic treatment, the ultrasonic treatment lasts for 20-40 minutes, and the ultrasonic temperature is 20-40℃.

[0015] Preferably, the oscillation process is carried out at 20℃-60℃ and 150rpm-250rpm for 1h-8h.

[0016] Preferably, the supernatant is filtered after centrifuging the dispersion solution, with a centrifugation speed of 5000 rpm and a centrifugation time of 4 min.

[0017] Preferably, the pretreated Sargassum biomass raw material is poured into a buffer solution, which is a sodium citrate buffer solution.

[0018] Preferably, the buffer concentration range is 0.1M / L-0.2M / L, the buffer volume is 20mL-50mL, and the pH value of the buffer is 4-7.

[0019] Preferably, the catalyst is cellulase, and the amount of cellulase used is 2 mg / mL-4 mg / mL.

[0020] Preferably, the enzymatic hydrolysis reaction is carried out in a constant temperature shaking chamber with a temperature range of 45℃-60℃ and a hydrolysis time of 12h-72h.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] This invention proposes an ultrasound-assisted method for pretreating Sargassum biomass with low-concentration potassium permanganate. Potassium permanganate, as a strong oxidant, offers significant advantages over traditional oxidants such as hydrogen peroxide and ozone, including high operational safety, low cost, mild pretreatment conditions, and ease of storage and transportation. These characteristics make potassium permanganate a potential application in biomass pretreatment, especially in the pretreatment of marine algae biomass. This invention involves adding Sargassum powder to deionized water and then adding potassium permanganate, which effectively removes impurities and harmful substances from the Sargassum, improving the efficiency of subsequent processing. Ultrasonic and oscillation treatments help to disperse the solution uniformly, facilitating subsequent centrifugation and filtration steps and reducing material loss. Therefore, using ultrasound-assisted low-concentration potassium permanganate solution to pretreat Sargassum biomass raw materials at room temperature utilizes the intense shear force and cavitation phenomenon generated by high-frequency ultrasonic vibration to enhance the oxidative decomposition of lignocellulose by the potassium permanganate solution. This removes lignin and hemicellulose from the Sargassum biomass while simultaneously making the biomass structure more porous and loose, reducing mechanical strength, and increasing the accessibility of cellulase. Therefore, the method proposed in this invention improves the lignin removal rate and hemicellulose removal rate after pretreatment of Sargassum, and has a high cellulose recovery rate, making it environmentally friendly and pollution-free.

[0023] Furthermore, by controlling the drying temperature and time, as well as the storage conditions, the quality and stability of the Sargassum powder can be ensured, avoiding any impact on subsequent processing due to improper storage. By controlling the solid-liquid ratio of Sargassum powder to deionized water, the appropriate solution concentration can be ensured—neither too dilute, leading to low processing efficiency, nor too concentrated, causing processing difficulties.

[0024] Furthermore, temperature control during ultrasonic and oscillation treatments helps maintain solution stability, preventing substance decomposition or denaturation due to excessively high temperatures. Time control during ultrasonic and oscillation treatments ensures adequate dispersion while avoiding unnecessary energy consumption caused by prolonged treatment.

[0025] Furthermore, by controlling the centrifugation speed and time, the solid and liquid components in Sargassum biomass can be effectively separated, thus improving the separation efficiency.

[0026] Furthermore, using sodium citrate buffer provides a suitable pH environment, which is beneficial for subsequent enzymatic hydrolysis reactions and improves reaction efficiency. By controlling the concentration and amount of buffer, the stability of the reaction system can be ensured, avoiding the impact of excessively high or low concentrations on reaction results. Maintaining the pH of the buffer within the range of 4-7 helps maintain enzyme activity and improves enzymatic hydrolysis efficiency.

[0027] Furthermore, using cellulase as a catalyst can specifically decompose cellulose, improving the utilization rate of cellulose in Sargassum biomass. By controlling the amount of cellulase used, the efficiency and effectiveness of the enzymatic hydrolysis reaction can be ensured, avoiding adverse effects due to excessive or insufficient dosage.

[0028] Furthermore, by conducting the enzymatic hydrolysis reaction in a constant temperature shaking chamber and controlling the rotation speed, temperature, and time, the uniformity and efficiency of the enzymatic hydrolysis reaction can be ensured, thereby increasing the cellulose content of Sargassum biomass. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a flowchart illustrating the process of pretreating Sargassum biomass at room temperature with ultrasound-assisted low-concentration potassium permanganate.

[0031] Figure 2 The images show scanning electron microscope (SEM) images of Sargassum powder after different treatments according to the present invention ((a) untreated; (b) ultrasonically treated; (c) treated with only low-concentration potassium permanganate; (d) ultrasonically treated with low-concentration potassium permanganate).

[0032] Figure 3 The Fourier transform infrared spectra of Sargassum powder after different treatments are shown below. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0034] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0035] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0036] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0037] The present invention will now be described in further detail with reference to the accompanying drawings:

[0038] The present invention proposes a method for pretreating Sargassum biomass, comprising the following steps:

[0039] Step 1: Add Sargassum powder to deionized water, then add potassium permanganate and stir to obtain the prepared solution;

[0040] Steps to obtain Sargassum powder:

[0041] Salted Sargassum was soaked and washed, then completely dried, ground and sieved, and stored at room temperature away from light to obtain Sargassum powder; the drying temperature was 100℃-120℃, and the drying time was 4h-8h.

[0042] The ratio of Sargassum powder, deionized water, and potassium permanganate is 0.5g-2.5g: 50mL-100mL: 0.05g-1g; the concentration of potassium permanganate is in the range of 0.1wt%-1wt%.

[0043] Step 2: The prepared solution is subjected to ultrasonic treatment and oscillation treatment in sequence to obtain a dispersion solution;

[0044] When performing ultrasonic treatment, the ultrasonic treatment time is 20-40 minutes and the ultrasonic temperature is 20-40℃.

[0045] When performing the oscillation treatment, oscillate at 20℃-60℃ and 150rpm-250rpm for 1h-8h.

[0046] Step 3: Centrifuge the dispersion solution and then filter the supernatant until the extracted liquid is neutral. Dry the filter residue to constant weight to obtain pretreated Sargassum biomass raw material.

[0047] The dispersion solution is centrifuged and the supernatant is then filtered. The centrifugation speed is 5000 rpm and the centrifugation time is 4 min.

[0048] Step 4: Pour the pretreated Sargassum biomass raw material into a buffer solution and add a catalyst to react, obtaining glucose in the supernatant, thus achieving the pretreatment of Sargassum biomass.

[0049] The pretreated Sargassum biomass raw material is poured into a buffer solution, which is sodium citrate buffer solution.

[0050] The buffer concentration range is 0.1M / L-0.2M / L, the buffer volume is 20mL-50mL, and the pH value of the buffer is 4-7.

[0051] The catalyst is cellulase, and the amount of cellulase used is 2 mg / mL-4 mg / mL.

[0052] The enzymatic hydrolysis reaction was carried out in a constant temperature shaking chamber with a temperature range of 45℃-60℃ and a hydrolysis time of 12h-72h.

[0053] The method is described in detail below:

[0054] Step 1: The raw material is fresh Sargassum fusiforme harvested from the sea. The fresh Sargassum fusiforme is salted, stored at low temperature, and transported. The salted Sargassum fusiforme is thoroughly soaked and washed, completely dried in an oven, ground, and passed through an 80-mesh sieve. It is then stored at room temperature in the dark. 50-100 mL of deionized water is added to an Erlenmeyer flask. 0.5-2.5 g of Sargassum fusiforme powder is added to the flask, maintaining a solid-liquid ratio of 1:20-1:100. 0.05-1 g of potassium permanganate is added, maintaining a concentration of 0.1 wt%-1 wt%. The mixture is stirred with a glass rod to ensure the Sargassum fusiforme powder is evenly dispersed in the solution. The oven temperature is 100-120℃, and the drying time is 4-8 hours until the Sargassum fusiforme powder reaches a constant weight.

[0055] Step 2: Place the prepared solution in an ultrasonic cleaner and sonicate at 200W-400W for 20-40 minutes. After sonication, place it in a constant temperature oscillation chamber at 20℃-60℃ for 1-8 hours for pretreatment. The oscillation speed of the chamber is 200-250 rpm. The ultrasonic frequency is 40KHz, and the ultrasonic temperature is 20-40℃.

[0056] Step 3: After the reaction is complete, centrifuge the solution and then filter the supernatant. Wash the centrifuged precipitate and the filter residue with deionized water repeatedly until the extracted liquid is neutral. Dry the filter residue in an oven at 90°C to constant weight to obtain pretreated Sargassum biomass raw material.

[0057] Step 4: After weighing the Sargassum biomass, pour it into an Erlenmeyer flask containing 0.1M / L-0.2M / L sodium citrate buffer (pH 4-7) at a volume of 20mL-50mL. Add cellulase at a concentration of 2mg / mL-4mg / mL buffer. Place the flask in a constant temperature shaking incubator at 45-60℃ for enzymatic hydrolysis at 150rpm for 12-72 hours. Use a biosensor to measure the glucose content in the supernatant after hydrolysis and determine the content of cellulose, hemicellulose, and acid-insoluble matter (AIR) in the pretreated Sargassum biomass.

[0058] Example 1:

[0059] A method for ultrasound-assisted pretreatment of Sargassum biomass with low concentration potassium permanganate includes the following steps:

[0060] (1) Soak and clean the salted Sargassum thoroughly, dry it in an oven at 120°C for 4 hours, grind it, pass it through an 80-mesh sieve, and store it in the dark at room temperature.

[0061] (2) Add 50 mL of deionized water to the conical flask, add 1 g of Sargassum powder obtained in step (1) to the conical flask, so that the solid-liquid ratio is 1:50, add 0.2 g of potassium permanganate to make the concentration 0.4 wt%, and stir with a glass rod to make the Sargassum powder disperse evenly in the solution.

[0062] (3) Place the solution prepared in step (2) in an ultrasonic cleaner and sonicate at 240W and 30℃ for 30 minutes. After sonication, place it in a constant temperature oscillation box and pre-treat at 40℃ for 4 hours. The rotation speed of the constant temperature oscillation box is 200rpm.

[0063] (4) After the reaction in step (3) is completed, the solution is centrifuged and the supernatant is filtered. The centrifuged precipitate and the filter residue are repeatedly washed with deionized water until the extracted liquid is neutral. The filter residue is dried in an oven at 90°C to constant weight to obtain pretreated Sargassum biomass raw material.

[0064] (5) After weighing the Sargassum biomass raw material obtained in step (4), pour it into a 50mL Erlenmeyer flask containing 0.1M / L sodium citrate buffer with a pH of 5 and add cellulase with 4mg / mL buffer. Place the Erlenmeyer flask in a constant temperature shaking incubator at 50℃ for 72h for enzymatic hydrolysis.

[0065] (6) The glucose content of the supernatant after enzymatic hydrolysis was measured using a biosensor, and the cellulose, hemicellulose and lignin content of the pretreated Sargassum biomass were measured using the standard method of the U.S. Department of Energy (NREL).

[0066] Example 2:

[0067] A method for pretreating Sargassum biomass with low concentration potassium permanganate using ultrasound at room temperature includes the following steps:

[0068] (1) Soak and clean the salted Sargassum thoroughly, dry it in an oven at 100°C for 8 hours, grind it, pass it through an 80-mesh sieve, and store it in the dark at room temperature.

[0069] (2) Add 100 mL of deionized water to the conical flask, add 1 g of Sargassum powder obtained in step (1) to the conical flask, so that the solid-liquid ratio is 1:100, add 1 g of potassium permanganate to make the concentration 1 wt%, and stir with a glass rod to make the Sargassum powder disperse evenly in the solution.

[0070] (3) Place the solution prepared in step (2) in an ultrasonic cleaner and sonicate at 200W and 20℃ for 20 minutes. After sonication, place it in a constant temperature oscillation box and pre-treat at 20℃ for 8 hours. The rotation speed of the constant temperature oscillation box is 250rpm.

[0071] (4) After the reaction in step (3) is completed, the solution is centrifuged and the supernatant is filtered. The centrifuged precipitate and the filter residue are repeatedly washed with deionized water until the extracted liquid is neutral. The filter residue is dried in an oven at 90°C to constant weight to obtain pretreated Sargassum biomass raw material.

[0072] (5) After weighing the Sargassum biomass raw material obtained in step (4), pour it into a 20mL Erlenmeyer flask containing 0.2M / L sodium citrate buffer with a pH of 4 and add cellulase with 3mg / mL buffer. Place the Erlenmeyer flask in a constant temperature shaking incubator at 45℃ for enzymatic hydrolysis for 48h.

[0073] (6) The glucose content of the supernatant after enzymatic hydrolysis was measured using a biosensor, and the cellulose, hemicellulose and lignin content of the pretreated Sargassum biomass were measured using the standard method of the U.S. Department of Energy (NREL).

[0074] Example 3:

[0075] A method for pretreating Sargassum biomass with low concentration potassium permanganate using ultrasound at room temperature includes the following steps:

[0076] (1) Soak and clean the salted Sargassum thoroughly, dry it in an oven at 110°C for 6 hours, grind it, pass it through an 80-mesh sieve, and store it in the dark at room temperature.

[0077] (2) Add 75 mL of deionized water to the conical flask, add 1.5 g of Sargassum powder obtained in step (1) to the conical flask, so that the solid-liquid ratio is 1:50, add 0.6 g of potassium permanganate to make the concentration 0.8 wt%, and stir with a glass rod to make the Sargassum powder disperse evenly in the solution.

[0078] (3) Place the solution prepared in step (2) in an ultrasonic cleaner and sonicate at 400W and 40℃ for 40 minutes. After sonication, place it in a constant temperature oscillation box and pre-treat at 30℃ for 6 hours. The rotation speed of the constant temperature oscillation box is 200rpm.

[0079] (4) After the reaction in step (3) is completed, the solution is centrifuged and the supernatant is filtered. The centrifuged precipitate and the filter residue are repeatedly washed with deionized water until the extracted liquid is neutral. The filter residue is dried in an oven at 90°C to constant weight to obtain pretreated Sargassum biomass raw material.

[0080] (5) After weighing the Sargassum biomass raw material obtained in step (4), pour it into a 30mL Erlenmeyer flask containing 0.15M / L sodium citrate buffer with a pH of 6 and add cellulase with 2mg / mL buffer. Place the Erlenmeyer flask in a constant temperature shaking incubator at 55℃ for 60h for enzymatic hydrolysis.

[0081] (6) The glucose content of the supernatant after enzymatic hydrolysis was measured using a biosensor, and the cellulose, hemicellulose and lignin content of the pretreated Sargassum biomass were measured using the standard method of the U.S. Department of Energy (NREL).

[0082] Example 4:

[0083] A method for pretreating Sargassum biomass with low concentration potassium permanganate using ultrasound at room temperature includes the following steps:

[0084] (1) Soak and clean the salted Sargassum thoroughly, dry it in an oven at 120°C for 5 hours, grind it, pass it through an 80-mesh sieve, and store it in the dark at room temperature.

[0085] (2) Add 50 mL of deionized water to the conical flask, add 2.5 g of Sargassum powder obtained in step (1) to the conical flask, so that the solid-liquid ratio is 1:20, add 0.5 g of potassium permanganate to make the concentration 1 wt%, and stir with a glass rod to make the Sargassum powder disperse evenly in the solution.

[0086] (3) Place the solution prepared in step (2) in an ultrasonic cleaner and sonicate at 320W and 30℃ for 40 minutes. After sonication, place it in a constant temperature oscillation box and pre-treat at 50℃ for 1 hour. The rotation speed of the constant temperature oscillation box is 250rpm.

[0087] (4) After the reaction in step (3) is completed, the solution is centrifuged and the supernatant is filtered. The centrifuged precipitate and the filter residue are repeatedly washed with deionized water until the extracted liquid is neutral. The filter residue is dried in an oven at 90°C to constant weight to obtain pretreated Sargassum biomass raw material.

[0088] (5) After weighing the Sargassum biomass raw material obtained in step (4), pour it into a 40mL Erlenmeyer flask containing 0.1M / L sodium citrate buffer with a pH of 7 and add cellulase with 3mg / mL buffer. Place the Erlenmeyer flask in a constant temperature shaking incubator at 60℃ for 12h for enzymatic hydrolysis.

[0089] (6) The glucose content of the supernatant after enzymatic hydrolysis was measured using a biosensor, and the cellulose, hemicellulose and lignin content of the pretreated Sargassum biomass were measured using the standard method of the U.S. Department of Energy (NREL).

[0090] Example 5:

[0091] A method for pretreating Sargassum biomass with low concentration potassium permanganate using ultrasound at room temperature includes the following steps:

[0092] (1) Soak and clean the salted Sargassum thoroughly, dry it in an oven at 110°C for 7 hours, grind it, pass it through an 80-mesh sieve, and store it in the dark at room temperature.

[0093] (2) Add 100 mL of deionized water to the conical flask, add 2 g of Sargassum powder obtained in step (1) to the conical flask, so that the solid-liquid ratio is 1:50, add 0.3 g of potassium permanganate to make the concentration 0.3 wt%, and stir with a glass rod to make the Sargassum powder disperse evenly in the solution.

[0094] (3) Place the solution prepared in step (2) in an ultrasonic cleaner and sonicate at 320W and 40℃ for 30 minutes. After sonication, place it in a constant temperature oscillation box and pre-treat at 60℃ for 2 hours. The rotation speed of the constant temperature oscillation box is 250rpm.

[0095] (4) After the reaction in step (3) is completed, the solution is centrifuged and the supernatant is filtered. The centrifuged precipitate and the filter residue are repeatedly washed with deionized water until the extracted liquid is neutral. The filter residue is dried in an oven at 90°C to constant weight to obtain pretreated Sargassum biomass raw material.

[0096] (5) After weighing the Sargassum biomass raw material obtained in step (4), pour it into a 30mL Erlenmeyer flask containing 0.2M / L sodium citrate buffer with a pH of 4 and add cellulase with 2mg / mL buffer. Place the Erlenmeyer flask in a constant temperature shaking incubator at 55℃ for 24h for enzymatic hydrolysis.

[0097] (6) The glucose content of the supernatant after enzymatic hydrolysis was measured using a biosensor, and the cellulose, hemicellulose and lignin content of the pretreated Sargassum biomass were measured using the standard method of the U.S. Department of Energy (NREL).

[0098] Example 6:

[0099] A method for pretreating Sargassum biomass with low concentration potassium permanganate using ultrasound at room temperature includes the following steps:

[0100] (1) Soak and clean the salted Sargassum thoroughly, dry it in an oven at 100°C for 5 hours, grind it, pass it through an 80-mesh sieve, and store it in the dark at room temperature.

[0101] (2) Add 50 mL of deionized water to the conical flask, add 0.5 g of Sargassum powder obtained in step (1) to the conical flask, so that the solid-liquid ratio is 1:50, add 0.05 g of potassium permanganate to make the concentration 0.1 wt%, and stir with a glass rod to make the Sargassum powder disperse evenly in the solution.

[0102] (3) Place the solution prepared in step (2) in an ultrasonic cleaner and sonicate at 400W and 20℃ for 40 minutes. After sonication, place it in a constant temperature oscillation box and pre-treat at 50℃ for 3 hours. The rotation speed of the constant temperature oscillation box is 200rpm.

[0103] (4) After the reaction in step (3) is completed, the solution is centrifuged and the supernatant is filtered. The centrifuged precipitate and the filter residue are repeatedly washed with deionized water until the extracted liquid is neutral. The filter residue is dried in an oven at 90°C to constant weight to obtain pretreated Sargassum biomass raw material.

[0104] (5) After weighing the Sargassum biomass raw material obtained in step (4), pour it into a 40mL Erlenmeyer flask containing 0.15M / L sodium citrate buffer with a pH of 5 and add cellulase with 3mg / mL buffer. Place the Erlenmeyer flask in a constant temperature shaking incubator at 45℃ for enzymatic hydrolysis for 36h.

[0105] (6) The glucose content of the supernatant after enzymatic hydrolysis was measured using a biosensor, and the cellulose, hemicellulose and lignin content of the pretreated Sargassum biomass were measured using the standard method of the U.S. Department of Energy (NREL).

[0106] Example 7:

[0107] A method for pretreating Sargassum biomass with low concentration potassium permanganate using ultrasound at room temperature includes the following steps:

[0108] (1) Soak and clean the salted Sargassum thoroughly, dry it in an oven at 120°C for 6 hours, grind it, pass it through an 80-mesh sieve, and store it in the dark at room temperature.

[0109] (2) Add 100 mL of deionized water to the conical flask, add 2.5 g of Sargassum powder obtained in step (1) to the conical flask, so that the solid-liquid ratio is 1:40, add 0.2 g of potassium permanganate to make the concentration 0.2 wt%, and stir with a glass rod to make the Sargassum powder disperse evenly in the solution.

[0110] (3) Place the solution prepared in step (2) in an ultrasonic cleaner and sonicate at 240W and 30℃ for 40 minutes. After sonication, place it in a constant temperature oscillation box and pre-treat at 40℃ for 5 hours. The rotation speed of the constant temperature oscillation box is 200rpm.

[0111] (4) After the reaction in step (3) is completed, the solution is centrifuged and the supernatant is filtered. The centrifuged precipitate and the filter residue are repeatedly washed with deionized water until the extracted liquid is neutral. The filter residue is dried in an oven at 90°C to constant weight to obtain pretreated Sargassum biomass raw material.

[0112] (5) After weighing the Sargassum biomass raw material obtained in step (4), pour it into a 50mL Erlenmeyer flask containing 0.2M / L sodium citrate buffer with a pH of 6 and add cellulase with 4mg / mL buffer. Place the Erlenmeyer flask in a constant temperature shaking incubator at 50℃ for 48h for enzymatic hydrolysis.

[0113] (6) The glucose content of the supernatant after enzymatic hydrolysis was measured using a biosensor, and the cellulose, hemicellulose and lignin content of the pretreated Sargassum biomass were measured using the standard method of the U.S. Department of Energy (NREL).

[0114] Example 8:

[0115] A method for pretreating Sargassum biomass with low concentration potassium permanganate using ultrasound at room temperature includes the following steps:

[0116] (1) Soak and clean the salted Sargassum thoroughly, dry it in an oven at 110°C for 8 hours, grind it, pass it through an 80-mesh sieve, and store it in the dark at room temperature.

[0117] (2) Add 50 mL of deionized water to the conical flask, add 1 g of Sargassum powder obtained in step (1) to the conical flask, so that the solid-liquid ratio is 1:40, add 0.4 g of potassium permanganate to make the concentration 0.8 wt%, and stir with a glass rod to make the Sargassum powder disperse evenly in the solution.

[0118] (3) Place the solution prepared in step (2) in an ultrasonic cleaner and sonicate at 320W and 30℃ for 20 minutes. After sonication, place it in a constant temperature oscillation box and pre-treat at 20℃ for 6 hours. The rotation speed of the constant temperature oscillation box is 200rpm.

[0119] (4) After the reaction in step (3) is completed, the solution is centrifuged and the supernatant is filtered. The centrifuged precipitate and the filter residue are repeatedly washed with deionized water until the extracted liquid is neutral. The filter residue is dried in an oven at 90°C to constant weight to obtain pretreated Sargassum biomass raw material.

[0120] (5) After weighing the Sargassum biomass raw material obtained in step (4), pour it into a 30mL Erlenmeyer flask containing 0.1M / L sodium citrate buffer with a pH of 7 and add cellulase with 4mg / mL buffer. Place the Erlenmeyer flask in a constant temperature shaking incubator at 55℃ for 60h for enzymatic hydrolysis.

[0121] (6) The glucose content of the supernatant after enzymatic hydrolysis was measured using a biosensor, and the cellulose, hemicellulose and lignin content of the pretreated Sargassum biomass were measured using the standard method of the U.S. Department of Energy (NREL).

[0122] Example 9:

[0123] A method for pretreating Sargassum biomass with low concentration potassium permanganate using ultrasound at room temperature includes the following steps:

[0124] (1) Soak and clean the salted Sargassum thoroughly, dry it in an oven at 120°C for 8 hours, grind it, pass it through an 80-mesh sieve, and store it in the dark at room temperature.

[0125] (2) Add 50 mL of deionized water to the conical flask, add 1 g of Sargassum powder obtained in step (1) to the conical flask, so that the solid-liquid ratio is 1:40, add 0.4 g of potassium permanganate to make the concentration 0.8 wt%, and stir with a glass rod to make the Sargassum powder disperse evenly in the solution.

[0126] (3) Place the solution prepared in step (2) in an ultrasonic cleaner and sonicate at 320W and 30℃ for 20 minutes. After sonication, place it in a constant temperature oscillation box and pre-treat at 20℃ for 6 hours. The rotation speed of the constant temperature oscillation box is 200rpm.

[0127] (4) After the reaction in step (3) is completed, the solution is centrifuged and the supernatant is filtered. The centrifuged precipitate and the filter residue are repeatedly washed with deionized water until the extracted liquid is neutral. The filter residue is dried in an oven at 90°C to constant weight to obtain pretreated Sargassum biomass raw material.

[0128] (5) After weighing the Sargassum biomass raw material obtained in step (4), pour it into a 50mL Erlenmeyer flask containing 0.1M / L sodium citrate buffer with a pH of 5 and add cellulase with 2mg / mL buffer. Place the Erlenmeyer flask in a constant temperature shaking incubator at 50℃ for 48h for enzymatic hydrolysis.

[0129] (6) The glucose content of the supernatant after enzymatic hydrolysis was measured using a biosensor, and the cellulose, hemicellulose and lignin content of the pretreated Sargassum biomass were measured using the standard method of the U.S. Department of Energy (NREL).

[0130] Example 10:

[0131] A method for pretreating Sargassum biomass with low concentration potassium permanganate using ultrasound at room temperature includes the following steps:

[0132] (1) Soak and clean the salted Sargassum thoroughly, dry it in an oven at 100°C for 7 hours, grind it, pass it through an 80-mesh sieve, and store it in the dark at room temperature.

[0133] (2) Add 50 mL of deionized water to the conical flask, add 1 g of Sargassum powder obtained in step (1) to the conical flask, so that the solid-liquid ratio is 1:50, add 0.35 g of potassium permanganate to make the concentration 0.7 wt%, and stir with a glass rod to make the Sargassum powder disperse evenly in the solution.

[0134] (3) Place the solution prepared in step (2) in an ultrasonic cleaner and sonicate at 240W and 30℃ for 30 minutes. After sonication, place it in a constant temperature oscillation box and pre-treat at 40℃ for 5 hours. The rotation speed of the constant temperature oscillation box is 200rpm.

[0135] (4) After the reaction in step (3) is completed, the solution is centrifuged and the supernatant is filtered. The centrifuged precipitate and the filter residue are repeatedly washed with deionized water until the extracted liquid is neutral. The filter residue is dried in an oven at 90°C to constant weight to obtain pretreated Sargassum biomass raw material.

[0136] (5) After weighing the Sargassum biomass raw material obtained in step (4), pour it into a 50mL Erlenmeyer flask containing 0.2M / L sodium citrate buffer with a pH of 5 and add cellulase with 3mg / mL buffer. Place the Erlenmeyer flask in a constant temperature shaking incubator at 55℃ for enzymatic hydrolysis for 72h.

[0137] (6) The glucose content of the supernatant after enzymatic hydrolysis was measured using a biosensor, and the cellulose, hemicellulose and lignin content of the pretreated Sargassum biomass were measured using the standard method of the U.S. Department of Energy (NREL).

[0138] Comparative test

[0139] Experimental Group 1: Salted Sargassum was thoroughly soaked and cleaned, dried in an oven at 110°C, ground, and passed through an 80-mesh sieve without any further processing to produce Sargassum powder raw material.

[0140] Experimental Group 2: Add 50 mL of deionized water to an Erlenmeyer flask, take 1 g of Sargassum powder prepared in Experimental Group 1, so that the solid-liquid ratio is 1:50, stir with a glass rod to make the Sargassum powder evenly dispersed in the solution, and place the prepared solution in an ultrasonic cleaner and sonicate at 240 W power for 30 min.

[0141] Experimental Group 3: Add 50 mL of deionized water to an Erlenmeyer flask, take 1 g of Sargassum powder prepared in Experimental Group 1 to make the solid-liquid ratio 1:50, add 0.15 g of potassium permanganate to control the concentration to 0.3 wt%, stir with a glass rod to make the Sargassum powder evenly dispersed in the solution, and put the prepared solution into a constant temperature shaking box at 20℃ for 4 hours for pretreatment. The rotation speed of the constant temperature shaking box is 200 rpm.

[0142] After weighing the Sargassum biomass obtained in experimental groups 1, 2, and 3, the biomass was poured into conical flasks containing 0.05 M / L sodium citrate buffer solution with a pH of 4.8, and 30 FPU / g cellulase was added. The conical flasks were then placed in a constant temperature shaking incubator at 50°C for enzymatic hydrolysis.

[0143] Example 1 of this invention is taken as experimental group 4, Example 2 as experimental group 5, Example 3 as experimental group 6, Example 4 as experimental group 7, and so on.

[0144] Analysis of the products obtained from the above 7 sets of experiments yielded the following results:

[0145] 1. The glucose content of the supernatant of the 7 groups of experimental enzymatic hydrolysis products was measured using a biosensor. The content of cellulose, hemicellulose and acid-insoluble substances in the 7 groups of experimental products was determined according to the standard method of the U.S. Department of Energy (NREL).

[0146] Table 1. Composition changes and test results of samples under different pretreatment conditions.

[0147]

[0148] Table 1 shows that the components of Sargassum fusiforme underwent significant changes before and after pretreatment. The cellulose content of the samples increased significantly after pretreatment, while the contents of hemicellulose and acid-insoluble substances decreased. Fourier transform infrared spectroscopy and scanning electron microscopy were used to characterize the samples after different pretreatments, analyzing the changes in cellulose, hemicellulose, and lignin before and after treatment. Example 1 showed the best results, retaining 23.43% of the cellulose content and achieving an enzymatic glucose yield of 100.87 mg / g.

[0149] Figure 2 Scanning electron micrographs of Sargassum powder after different pretreatments, by Figure 2 In (a), it can be observed that the Sargassum biomass has a complete and compact structure when untreated, and the surface of the raw material is relatively smooth and flat, which greatly reduces the accessibility of enzymes. Figure 2 (b) shows Sargassum powder after only ultrasonic pretreatment. It can be observed that ultrasonic treatment did not cause greater damage to the surface of the Sargassum powder; its surface structure remained intact and dense. Figure 2 (c) and Figure 2(d) shows the biomass after potassium permanganate treatment. It can be seen that the biomass structure of Sargassum is damaged after treatment, and a large number of grooves appear on the surface, showing a more disordered arrangement. The Sargassum powder changes from dense and intact to loose and porous. The potassium permanganate treatment destroys the original complex structure of Sargassum biomass. However, compared with the treatment, the potassium permanganate pretreatment assisted by ultrasound treatment is significantly more damaging.

[0150] Figure 3 Middle, 3400cm -1 The absorption peak at 2927 cm⁻¹ is related to the OH stretching vibrations of phenolic, carboxyl, and alcohol groups. -1 The absorption peak at 1637 cm⁻¹ represents the stretching vibrations of the methyl and methylene groups of the CH group, indicating the presence of lignin. Simultaneously, the stretching vibration of the benzene ring causes the peak at 1637 cm⁻¹. -1 The strong peak at 1425 cm⁻¹ is also a marker of lignin. -1 The absorption peak at 1514 cm⁻¹ is due to the C–H stretching vibration of lignin. -1 This is a characteristic peak of lignin, due to the vibration of the lignin aromatic skeleton, at 1166 cm⁻¹. -1 The observed decrease in strength indicates the removal of eugenyl, guaiacol, and hydroxyphenyl groups from the lignin, 831 cm. -1 The absorption peak at 1028 cm⁻¹ is related to the plane vibration of syringyl lignin. -1 The nearby bands belong to CO vibrations, originating from the polysaccharides of Sargassum. The graph clearly shows that the lignin content of the Sargassum powder decreased significantly after processing.

[0151] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for ultrasound-assisted pretreatment of Sargassum biomass with low concentration potassium permanganate, characterized in that, Includes the following steps: Add Sargassum powder to deionized water, then add potassium permanganate and stir to obtain the prepared solution. The prepared solution was subjected to ultrasonic treatment and oscillation treatment in sequence to obtain a dispersion solution; Centrifuge the dispersion solution and then filter the supernatant until the extracted liquid is neutral. Dry the filter residue to constant weight to obtain pretreated Sargassum biomass raw material. The pretreated Sargassum biomass raw material was poured into a buffer solution and a catalyst was added to react, resulting in glucose supernatant, thus achieving the pretreatment of Sargassum biomass. The ratio of Sargassum powder, deionized water, and potassium permanganate is 0.5 g - 2.5 g : 50 mL - 100 mL : 0.05 g - 1 g; the concentration of potassium permanganate is in the range of 0.1 wt% - 1 wt%.

2. The method for ultrasound-assisted pretreatment of Sargassum biomass with low concentration potassium permanganate according to claim 1, characterized in that, Steps to obtain Sargassum powder: Salted Sargassum was soaked and washed, then completely dried, ground and sieved, and stored at room temperature away from light to obtain Sargassum powder; the drying temperature was 100℃-120℃, and the drying time was 4 h-8 h.

3. The method for ultrasound-assisted pretreatment of Sargassum biomass with low concentration potassium permanganate according to claim 1, characterized in that, When performing ultrasonic treatment, the ultrasonic treatment time is 20-40 minutes and the ultrasonic temperature is 20-40℃.

4. The method for ultrasound-assisted pretreatment of Sargassum biomass with low concentration potassium permanganate according to claim 1, characterized in that, When performing the oscillation treatment, oscillate at 20℃-60℃ and 150 rpm-250 rpm for 1 h-8 h.

5. The method for ultrasound-assisted pretreatment of Sargassum biomass with low concentration potassium permanganate according to claim 1, characterized in that, The dispersion solution is centrifuged and the supernatant is then filtered. The centrifugation speed is 5000 rpm and the centrifugation time is 4 min.

6. The method for ultrasound-assisted pretreatment of Sargassum biomass with low concentration potassium permanganate according to claim 1, characterized in that, The pretreated Sargassum biomass raw material is poured into a buffer solution, which is sodium citrate buffer solution.

7. The method for ultrasound-assisted pretreatment of Sargassum biomass with low concentration potassium permanganate according to claim 1, characterized in that, The buffer concentration range is 0.1 M / L-0.2 M / L, the buffer volume is 20 mL-50 mL, and the pH value of the buffer is 4-7.

8. The method for ultrasound-assisted pretreatment of Sargassum biomass with low concentration potassium permanganate according to claim 1, characterized in that, The catalyst is cellulase, and the amount of cellulase used is 2 mg / mL-4 mg / mL.

9. The method for ultrasound-assisted pretreatment of Sargassum biomass with low concentration potassium permanganate according to claim 1, characterized in that, The enzymatic hydrolysis reaction was carried out in a constant temperature shaking chamber with a temperature range of 45℃-60℃ and a hydrolysis time of 12 h-72 h.

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