CN114907896A - Ginkgo leaf enzymolysis treatment method and application thereof - Google Patents

Abstract

The invention belongs to the technical field of biofuels, and particularly discloses a ginkgo leaf enzymolysis treatment method and application thereof. Explores the application possibility of the ginkgo leaf residues treated by the cellulase in the field of processing solid biofuel and provides insight for effectively treating forest residues.

Description

A kind of Ginkgo biloba enzymolysis treatment method and its application

technical field

The invention belongs to the technical field of biofuels, and in particular relates to an enzymatic hydrolysis treatment method of Ginkgo biloba leaves and applications thereof.

Background technique

Due to the acceleration of industrialization and urbanization, the amount of biological waste is increasing rapidly. Biowaste is a potential sustainable energy source with the advantages of being cheap, readily available, biodegradable and reducing greenhouse gas emissions. One of the most viable renewable energy sources is waste from forest residues due to their abundance, such as bark, wood chips and wood chips, which are wastes associated with the processing of forest products. Some of the work reported in the literature focuses on the biochemical and thermochemical transformations of wood waste into fuel products, such as Phyllostachys edulis, Jatropha curcas, and Cycad cycads. Furthermore, an analysis of five tree species (willow, boxwood, maple, cork oak, sycamore) very common in urban planting, Liquidambar (Liquidambarstyraciflua L.) can show that it is possible to use leaves to produce high-quality biofuels .

Ginkgo biloba is a very popular tree species with high medicinal, ecological, ornamental and scientific value. It has been widely introduced and cultivated in my country, with a planting area of nearly 200,000 hectares. Ginkgo biloba has been used as a medicine for thousands of years, and recently ginkgo biloba extract products have become the focus of herbal medicine, with annual global sales exceeding $10 billion. However, the large amount of Ginkgo biloba residues (GLR) from the pharmaceutical industry and urban greening has not attracted enough attention. In general, logistics management and storage of GLRs becomes more difficult and expensive due to the low bulk density. The traditional method is to directly discard GLR, ignoring potential environmental pollution and biomass waste. Thermochemical conversion (pyrolysis) and biomass densification (pelletization or shaping) processes could be promising residue management options, converting GLRs into valuable feedstocks that are easier to transport, store, handle and utilize.

Flavonoids are the main active components of Ginkgo biloba, and various methods are used to assist the extraction of flavonoids from Ginkgo biloba, such as enzyme-assisted extraction. Enzyme-assisted extraction is an emerging technology that accelerates the release of bioactive components from Ginkgo biloba leaves through the hydrolysis and breakdown of cell wall components (cellulose). For example, the study found that the content of total flavonoids in the enzyme-assisted extraction of Ginkgo biloba was 102% higher than that in the absence of enzymes. In addition, studies have shown that for biomass with high cellulose content, the content of volatiles generated by pyrolysis is large, and the thermal stability of the corresponding material becomes poor. Analysis of 6 agricultural biomass wastes showed a negative linear dependence between cellulose content in pellets and their density and durability. However, information on the pyrolysis kinetics and particle properties of enzymatically treated GLRs is not readily available, which will hinder the efficient optimization of GLR utilization routes. Therefore, the present invention provides a method for enzymatic hydrolysis of Ginkgo biloba leaves and its application.

SUMMARY OF THE INVENTION

In order to solve the above-mentioned problems, the primary purpose of the present invention is to provide a method for enzymatic hydrolysis of Ginkgo biloba leaves and its application.

The specific technical scheme of the present invention includes:

The invention provides an enzymatic hydrolysis treatment method for ginkgo leaves, which comprises the steps of grinding ginkgo leaves, sieving and drying to obtain ginkgo leaf powder, soaking the ginkgo leaf powder in a cellulase treatment solution at room temperature, and then leaching through water immersion treatment. The enzymatic hydrolysis residue of Ginkgo biloba powder can be filtered and dried at last.

As a further optimized solution of the present invention, the cellulase treatment solution is a 60% ethanol solution containing cellulase at a concentration of 100-200 mg/g.

The present invention also provides the application of the enzymatic hydrolysis treatment method for Ginkgo biloba leaves as described above in processing solid biofuels.

The present invention also provides a kind of ginkgo biloba solid fuel particle, which is obtained by granulating and granulating the ginkgo biloba residue obtained by any of the above-mentioned treatment methods as the main raw material.

The present invention also provides a preparation method of the above-mentioned Ginkgo biloba solid fuel particles, comprising the following steps:

(1) Ginkgo biloba leaves are ground and sieved by a grinder, and dried at 45°C for 48 hours to obtain ginkgo biloba powder for use;

(2) soak the ginkgo biloba powder obtained in step (1) in a 60% ethanol solution with a concentration of 100-200 mg/g cellulase at room temperature for 24 hours, and after solid-liquid separation, leave the solid and add 40 g of deionized water at room temperature. The enzymatic hydrolysis residue of ginkgo biloba powder was leached with water for 2 hours, and then the enzymatic hydrolysis residue was filtered to keep the filter residue, and the ginkgo leaf residue was obtained after drying in an oven, which was stored in a sealed environment for future use;

(3) The ginkgo biloba residue obtained in step (2) is granulated into granules.

As a further optimized solution of the present invention, in the step (3), before the granulation, the wet-based moisture content of the ginkgo leaf residue is adjusted to be less than 10%.

As a further optimized solution of the present invention, in the step (3), the granulation equipment selects a single particle device with an inner diameter of 6.35 mm and a length of 90 mm.

Working principle: Ginkgo biloba leaves belong to lignocellulosic biomass. Lignocellulosic biomass has many structural characteristics, most of which exist in the form of biopolymers, including cellulose, hemicellulose and lignin. Biopolymers are not only in plant cell walls. a single unit and are closely connected. Lignin and carbohydrates such as cellulose and hemicellulose form lignin-carbohydrate complexes. Hemicellulose provides growth points for lignin through ether linkages, which anchor lignin to plant wall polysaccharides and can lead to recalcitrance. Since cellulose is surrounded by hemicellulose and lignin, the presence of hemicellulose and lignin components largely limits the accessibility of cellulose to enzymes as they physically block cellulose during enzymatic hydrolysis Attacked by enzymes, hemicellulose removal is more important than lignin removal, creating pores for cellulase to enter. This promotes the accessibility of cellulose and further improves the breaking of long cellulose chains in the cell wall.

To sum up, the beneficial effects of the present invention are:

The invention utilizes cellulase to treat ginkgo leaves to obtain ginkgo leaf residue (GLR) to improve the extraction rate of valuable flavonoids to produce dense solid fuel particles. The results of scanning electron microscope (SEM) and specific surface area detection (BET) show that the enzyme treatment The latter samples became rougher and cracked as the specific surface area (SSA) increased. The higher calorific value of the 100 mg/g and 200 mg/g enzyme-treated samples increased from 17.8 MJ/kg to 18.9 MJ/kg and 19.3 MJ/kg, respectively. The durability and hardness of granules made from 200mg/g (optimal) enzyme treatment increased from 73.4% and 0.8N/ ^mm2 to 80.8% and 1.3N/ ^mm2 compared to granules made from untreated material . Kinetic analysis showed that the activation energy of 200 mg/g enzyme-treated pellets decreased from 45.5 KJ/mol to 34.2 KJ/mol in the first-order reaction model, and from 95.8 KJ/mol to 95.8 KJ/mol in the three-dimensional diffusion model. 77.8KJ/mol, thus, there are application possibilities in the field of processing solid biofuels from Ginkgo biloba residues treated with cellulase, and provide insights for better effective treatment of forest residues.

Description of drawings

Fig. 1 is a graph showing the effect of treating Ginkgo biloba leaves on the extraction rate of total flavonoids with different enzyme concentrations;

Figure 2 is an enzyme catalytic domain acting on the surface of crystalline cellulose;

Figure 3 shows the FTIR results of all particles;

Figure 4 is the SEM image of all the particles, wherein a-e are the particles of raw ginkgo leaves, leaching samples, E0 samples, E2.5 samples, and E5.0 samples in turn;

Figure 5 shows the DTG results for all particles.

Detailed ways

The application will be described in further detail below in conjunction with the accompanying drawings. It is necessary to point out that the following specific embodiments are only used to further illustrate the application, and should not be construed as limiting the protection scope of the application. Those skilled in the art can The above application content makes some non-essential improvements and adjustments to this application.

1. Materials

Unless otherwise specified, the methods used in this example are conventional methods known to those skilled in the art, and the reagents and other materials used, unless otherwise specified, are commercially available products.

2. Methods

A sample of Ginkgo biloba leaves was ground into powder by a Retsch mill (model SM100, Retsch Inc. Newtown, PA) with a mesh size of 3.2 mm, and dried in an oven at 45°C for 48 h.

Four equal parts of 4.0g ginkgo biloba powder were taken, and three equal parts of ginkgo leaves were soaked in 200ml of 60% ethanol solution containing 0, 100 and 200mg/g cellulase at room temperature for 24h. The cellulase was Trichoderma Vride cellulase (50u/mg), which was provided by Shanghai Yuanye Biotechnology Co., Ltd., China. After solid-liquid separation, 40 g of deionized water was added to the solid for 2 h at room temperature to extract the enzymatic hydrolysis residue. Then filter and leave the filter residue to be dried in an oven, and stored in a sealed glass jar for further analysis (hereinafter referred to as E0, E2.5, E5.0 samples), the fourth aliquot of Ginkgo biloba powder was added 40g deionized water at room temperature to soak Extracted for 2 hours, then filtered to leave the filter residue and dried in an oven to obtain the leaching sample. The control group was the same amount of raw ginkgo leaves (ie, the powder of ginkgo leaves without any treatment).

The treated samples of the above groups were respectively made into pellets with a single pellet device with an inner diameter of 6.35 mm and a length of 90 mm. Specifically, the heater was turned on by a PID temperature controller to raise the temperature of the mold (wrapped with heating tape) to 80°C. When making pellets, the crosshead of an MTI machine (Model 50K Universal, Measurement Technologies, Inc.) presses the material into the center of the mold. The bottom of the mold was open and closed with a removable stopper to adjust the wet basis moisture content of each set of samples to 10%. 10 pellets (hereinafter referred to as leaching pellets, E0, E2.5, E5.0 pellets) were prepared from each group of samples and stored in separate glass bottles for further analysis, and the control group was the same number of leaf pellets (ie granules obtained by granulating Ginkgo biloba powder without any treatment).

1. Enzyme-assisted extraction and molecular dynamics (MD) simulation of total flavonoids

Collect 0.5ml of the filtrate of E0, E2.5, and E5.0 samples treated with different concentrations of cellulase, respectively, and detect the total flavonoid content by a commercial analysis kit (Nanjing Jiancheng Bioengineering Institute, China). The results are shown in Figure 1 In order to better demonstrate the effect of enzymatic treatment, molecular dynamics (MD) simulations and free energy calculations were applied to the enzyme and pure crystalline cellulose systems, aiming to elucidate carbohydrate-protein interactions that drive polysaccharide translocation in enzymes The effect, in particular, was to mimic the structure of cellulose in an equal volume mixture of ethanol solution and cellulase. CHARMM software was used to set up the system and the results are shown in Figure 2.

Analysis of the results: As shown in Figure 1, the extraction rate of total flavonoids increased with the increase of enzyme concentration. Compared with the control group without adding enzyme (EO sample), the treatment of 100mg/g and 200mg/g enzyme solution made total flavonoids. The extraction rates were significantly improved by 19.4% and 50.2%, respectively. The main reason for the increase in total flavonoid production is that the presence of cellulase leads to the destruction of the cell wall. Specifically, the cellulase (1,4-β-D-glucanoglucoside hydrolase) used in this work was able to facilitate the removal of hemicellulose. As the hemicellulose is removed, the bonds of the hemicellulose lignin weaken and the cellulose can be more exposed to enzymes. Therefore, this enzyme binds more sites to cellulose, promoting the breakdown of crystalline cellulose. With the destruction of the cell wall structure, the extraction of flavonoids becomes easier and more sufficient, thereby increasing the yield of total flavonoids;

Figures 2a and b show the effect of simulating different enzyme doses (100 mg/g and 200 mg/g) at the same time. The results show that cellulose Iβ fibers consist of 18 chains, each of which contains 12 glucose monomers (DP12), and for the E2.5 and E5.0 samples, one of the cellulose chains is pulled out by the enzyme and enters the protein site Cellulose disintegration. Enzymes depolymerize cellulose through a progressive reaction mechanism in which a single cellulose chain binds to the enzyme from the reducing end and then enters the enzyme channel. After the cellulose chain is processed into precise cellulase sites, it is favorable for the binding probability of cellulose and cellulase, thereby improving the enzymatic hydrolysis efficiency. In addition, this result was also confirmed by the CrI results (Table 2), which decreased from 18.4% in raw Ginkgo biloba to 17.4% and 17.0% in E2.5, E5.0 samples with the increase of enzyme dose, which were comparable to E0 samples. 18.5% is almost the same.

2. Industrial analysis and elemental analysis

Each set of samples was sequentially analyzed by industry according to American Test and Materials Methods Standards (ASTM D3174-04 and ASTM D3175-89). Final analysis was performed with a Vario E1 cube element analyzer (Elementar GmbH, Germany). Fixed carbon (FC) content and oxygen content were calculated using the differential method. The crystallinity index CrI was determined by XRD diffractometer. The heating value (HHV) was determined by using a bomb calorimeter (Parr model 6100) with continuous temperature recording. A small amount of 0.5-1.0 g of each group of samples was used, and the measurement was repeated three times, and the results were averaged, as shown in Table 1-2.

Table 1 Industrial Analysis, Elemental Analysis and Calorific Value

Table 2 Chemical composition and CrI

Analysis of the results: Generally speaking, water immersion helps to reduce the ash content. However, the results of the present application found that the water immersion treatment did not affect the volatile content nor the ash content. The reason is that the fly ash of most straw samples is attached to the root of the straw, while the fly ash is not a structural ash in the tissue, and the ash attached to the leaf surface is less, and most of the ash is the structural ash in the cell wall. Therefore, the water immersion treatment did not lead to a reduction in ash content, and in addition, the ash content of the E5.0 sample decreased from 12.0% to 8.7% compared with raw Ginkgo biloba leaves. High ash content is a major limitation for all agricultural biomass utilization. During combustion and gasification, high ash content can lead to slagging, scaling and corrosion. The lower ash content and higher fixed carbon content after enzyme treatment resulted in an increase in HHV from 17.9 MJ/kg to 19.3 MJ/kg with increasing enzyme dosage. The increase in carbon content and the decrease in oxygen content resulted in a decrease in H/C and O/C molar ratios, which improved the fuel properties of Ginkgo biloba.

The most suitable particles for commercialization need to meet low ash content and high calorific value. According to the International Standard (Classification of Coal, ISO11760-2005), the enzyme-treated samples were classified as low-ash coal, while the raw Ginkgo biloba leaves without any treatment and the water-soaked raw Ginkgo biloba leaves were classified as medium-ash coal. The HHV of all samples in this application conforms to the Chinese National Standard (Part 3 of Coal Quality Classification: Calorific Value, GB/T 15224.32010) indicating that the HHV of low-rank coal is lower than 16.30 MJ/kg. It is further seen that the HHV and ash contents of the E2.5 and E5.0 samples of the present application are better than generally accepted fuel values, indicating their potential for use as fuels.

As shown in Table 2, the hemicellulose (5.2%) and cellulose (20.4%) content and the crystallinity index (CrI: 17.0%) decreased significantly in the E5.0 sample (Fig. lb). Removal of hemicellulose is more important than that of lignin and can create pores for cellulase entry. Amorphous cellulose is rapidly degraded to cellobiose by cellulases, whereas crystalline cellulose is hydrolyzed at a much slower rate, which promotes cellulose accessibility and further improves the breaking of long cellulose chains in the cell wall.

3. Structural analysis

(1) The crystal structure was investigated by a Bruker D8 Advance X-ray diffractometer (Bruker, Germany) at 1% cobalt radiance/minimum in 0.01 increments, operating voltage and current of 40kv and 50ma, respectively, 2θ (5-65) And compared with the XRD data obtained in the literature using copper targets.

(2) FTIR (Tensor-27, Bruker Optics Inc., Billerica, MA) spectra (4500-400 cm ⁻¹ ) were recorded to characterize changes in typical functional groups of virgin and treated particles. Each set of particles was mixed with KBr in a mass ratio of 1:100, ground and pressed into flakes. Then, the slices were loaded into the diffuse sampling head and kept flat. Spectra were recorded between 4000cm ^-1 and 400cm ^-1 with a resolution of 4cm ^-1 and a scan speed of 128min ^-1 . The results are shown in Figure 3 .

(3) Hitachi S4700 (Hitachi, Japan) used scanning electron microscopy (SEM) to evaluate the morphological changes of fibers after hydrothermal pretreatment. Samples were mounted on top of sample stubs and coated with gold under vacuum. All photographs were taken at an accelerating voltage of 10-20 kV. Before the SEM test, each group of particles was dried at 40 °C for 48 h, and the results are shown in Figure 4.

(4) Specific surface area (SSA), pore volume (V _p ) and average pore size (D _p ) were measured by physical adsorption of nitrogen in air -196°C using an ASAP 2020 Surface Area and Pore Size Analyzer (Micromeritics, Atlanta, GA ). The specific surface area of the particles was calculated using the BET method, and the pore size was evaluated by applying the Barrett-Joyner-Halenda (BJH) algorithm to the isotherm desorption branch, and the results are shown in Table 3.

Table 3 SSA and pore volume of foliar pellets and pellets for each treatment

Analysis of results: Figure 3 shows the FTIR results for all particles. The stretching vibrational carbonyl band (C=O) at 1733 cm ^-1 and the gruppi acetilici (COC) at 1247 cm ^-1 can be seen in the figure - decreasing with increasing enzyme dose, implying a significant decrease in hemicellulose content. As shown in Table 2, this enzyme can remove most of the hemicellulose, when the absorption peak at 1430 cm ^-1 corresponds to crystalline cellulose, and the _CH bending vibration of 893 cm- ¹ corresponds to amorphous cellulose. Untreated Ginkgo leaves showed almost no peaks of amorphous cellulose, while E2.5 and E5.0 particles showed very small peaks. This means that enzymes help increase amorphous cellulose. The crystalline cellulose peak only increased for E5.0 particles. This suggests that Enzyme 5.0 helps expose crystalline cellulose and is easier to detect. The band at 1630 cm ^-1 represents the stretching vibration of C=C in the aromatic ring, which is generally considered to be the lignin symbol.

Table 3 lists the SSA, _Vp and _Dp for all particles. Leaf particles and leaching particles have few large globules. For E0 particles, pores were detected despite their small size. When the enzyme dosage was increased to 2.5 and 5.0, there were more and more macrospheres in the particles, thus increasing the microporosity. The enhancement of _Vp promotes the increase of specific surface area. Such micropores are formed by removing hemicellulose. This is also confirmed by the SEM results (Figure 4). The surface of the leaf particles was smooth and intact (Fig. 4a). The surface of the E0 particles becomes wrinkled. As for the E2.5 and E5.0 particles, the surface not only became rough, but also cracked, resulting in a significant increase in SSA. When the enzyme dosage reached 5.0, the pore size increased significantly, and obvious voids appeared in the particle structure (Fig. 4e). The decomposition of most of the hemicellulose and some of the cellulose freed up space for fibers, thereby increasing the specific surface area, pore volume and average pore size of the treated particles.

4. Particle characteristics

The pellets were stored in sealed glass vials under laboratory conditions with an average temperature of 20 ± 2 °C and a relative humidity of 75 ± 5%. Measure the mass, length and diameter of the particles. The density can then be calculated. Particle durability was measured using a single particle durability analyzer (internal dimensions 60 x 60 x 60 mm, BURREL shaker, model 75). After shaking individual granules, sieve all contents through a 3.15mm screen to separate broken granules. Weigh the remaining mass on the sieve to four decimal places. Durability is calculated as the ratio of the mass on the sieve to the original mass. The Meyer Hardness (HM) test is performed by placing a cylindrical pellet horizontally between two metal plates. The compression ratio was set at 5 mm/min and stopped when the particles were broken, and the results are shown in Table 4.

Table 4 Mass Density, Energy Density, Durability, Hardness and Energy Input

Analysis of Results: Table 4 lists the mass density and energy density of the pellets made from green leaf pellets and treated pellets. The mass density of the E5.0 particles increased, reaching a maximum value of 1.27 g/cm ³ . The increase in mass density is due to the destruction of the structure of Ginkgo biloba. Table 1 also shows that the bulk density of E5.0 particles increased from 188.2 kg/m ³ of raw Ginkgo biloba to 213.9 kg/m ³ . The increase in bulk density allows for easier compaction of the treated particles and greater mass per unit volume. It can also be seen in the SEM images that as the enzyme dose is increased, the treated particles are also fragmented. The energy density is determined by the mass density and HHV. With the increase of mass density and HHV after enzyme treatment, the energy density of E0, E2.5 and E5.0 particles increased by 6.7%, 13.5% and 18.7%, respectively.

The durability and hardness of the pellets are the main mechanical properties for evaluating the quality of the pellets. As shown in Table 4, the durability and hardness of the leached particles were almost the same as the green leaf particles, indicating that water immersion did not affect the durability or hardness. In contrast, the durability of the E5.0 particles increased from 73.4% to 80.8% and the hardness increased from 0.8 N/mm ² to 1.3 N/mm ² . Compared to leaf pellets, as shown in Table 4, the durability was in the range of 73.4% to 80.8%, but not as high as wood pellets or straw pellets. The poor durability and strength properties of blade particles are caused by two main reasons: First, the particle size of the blade is not needle-like, which means that the shape of the ground blade is more uniform. Due to the greater weight per unit volume, generally uniform particles help to produce denser particles. However, the presence of elongated particles is another important parameter for the formation of adhesion through mechanical interlocking. There is a suitable range of fine and long pellets to produce durable pellets. Second, the mechanical strength of the pellets is also determined by the chemical composition. The low lignin content in the leaf samples was unable to form strong bridges between the particles to improve mechanical strength, which resulted in poor durability and hardness of the particles due to the lack of solid bridges between the particles.

There was no significant difference in durability and hardness between green leaf particles, leached particles and E0 particles (P>0.05). When the enzyme concentration was increased from E2.5 to E5.0, the particle durability increased by 6.4%, 10.1%, and the hardness increased by 37.5% and 62.5%, respectively. The increase in durability and hardness is due to the interpenetration of the increased lignin content. During the heat pelletizing process, the lignin in the treated pellets softens into its pellet matrix. During heat granulation (80°C), the lignin softens and begins to flow and engulf adjacent granules. As the particles cool, the softened (sticky) lignin is converted into smooth solidified lignin, enabling the formation of solid bridges between the treated particles. The energy consumption remained in the range of 15.1-16.1 J, and there was no significant difference in the energy consumption of all pellets (P>0.05). In general, as the lignin content increases, the ratio of molds and pellets, and pellets to pellets all lead to an increase in energy consumption in the pelletizing process. Compared with woody and agricultural biomass, the lignin content of the enzyme-treated leaves of the present application is lower, which is the main reason for the energy consumption to remain unchanged.

5. Thermogravimetric analysis

Pyrolysis analysis was performed under nitrogen using a thermogravimetric analyzer (TGA model Q550, TA Instruments). Approximately 10 mg of granules are used each time. The decomposition behavior was studied by the following steps: (1) a heating rate of 20 °C/min from ambient temperature to 105 °C; (2) isothermal for 10 min; (3) a heating rate of 20 °C/min from 105 °C to 800 °C; (4) isothermal for 10 minutes. The Devolatilization Index (D _i ), which represents the difference in volatiles between treated and untreated particles, was calculated from the data collected. T _i is the initial devolatilization temperature; T _max is the maximum mass loss temperature; DTG _max is the maximum decomposition rate and ΔT1 _/2 is the temperature interval for half of the DTG _max value.

Analysis of the results: As shown in Fig. 5, the pyrolysis process of the green leaf particles and the treated particles can be divided into three separate stages. In the first stage, a small amount of volatile and organic content is dehydrated below 150°C through the loss of free water and chemically bound water. In the second stage, the volatiles devolatilization stage occurs at 150-500 °C with the largest mass loss, and the last carbonization stage occurs at 500-800 °C. The volatiles devolatilization stage is the main pyrolysis stage for all pellets. At this stage, hemicellulose, the most unstable and easily pyrolyzed among hemicellulose, cellulose and lignin, begins to decompose in the temperature range of 220-315 °C. In contrast, the decomposition temperature of cellulose is higher (315°C to 390°C) because the polymer is composed of long-chain glucose without branching. Lignin decomposes in a wider temperature range of 160-500°C. During the pyrolysis stage, a large amount of volatile substances are decomposed into small molecular weight gases, such as hydrocarbons, _CO2 , _CH4 , etc. The third stage is the combustion process of a small amount of fixed carbon; mainly the decomposition of high-boiling organics. It can be seen from the figure that at about 220 °C, the hemicellulose decomposition peaks in the leaf particles, leaching particles and E0 particles are obvious. The peaks for E2.5 and E5.0 particles almost disappeared, indicating that hemicellulose was removed after enzymatic treatment. The cellulolysis peak shifted to the low temperature region, and the peak intensity was enhanced by E5.0 particles.

Table 5 Pyrolysis parameters of different particles

As shown in Table 5, the maximum weight loss peak temperature and maximum weight loss rate of the green leaf particles were 321.1°C and 9.1%/min, respectively. After water immersion, the maximum weight loss peak temperature decreased to 312.6 °C with the same rate of 9.1%/min. At 310.8°C, the maximum weight loss rate of EO particles was 9.6%/min. Maximum weight loss peak temperature for E2. E2.5 and E5.0 particles had _Rmax of 9.6% and 10.0%/min at 305.2°C and 306.6°C, respectively. Di was used to evaluate the performance of volatile release. The higher the Di, the easier the release of volatile substances. The Di value of the enzyme-treated granules showed an upward trend, especially the E5.0 granules was 1.8, which was 28.6% higher than that of the leaf-treated granules. This indicates that the E5.0 particles are more easily decomposed at low temperature.

Table 6 Kinetic parameters of all particles

Table 6 lists the calculated kinetic parameters of the pyrolysis process in the main temperature range of 190 to 350 °C. Different from wood and straw, the particles of the present application showed two peaks in this temperature range. The reaction mechanism conforms to the three-order reaction model and the three-dimensional diffusion model, and the R2 is greater ^than 0.98. The activation energy E and exponential prefactor A of the different models show the same trend for all pellets. Activation energy of E5.0 particles For the reaction model, the activation energy E decreased from 45.5 to 34.2, and for the 3D diffusion model, the activation energy E decreased from 95.8 to 77.8. The lower activation energy means that particles made from treated particles require less energy to initiate the reaction. The destruction of the fiber structure is the main reason to promote the mass and heat transfer improvement of the pyrolysis process. Real-time SEM images, enhanced SSA, _Vp and _Dp support this claim.

3. Conclusion

The invention utilizes cellulase to treat ginkgo leaves to obtain ginkgo leaf residue (GLR) to improve the extraction rate of valuable flavonoids to produce dense solid fuel particles. The results of scanning electron microscope (SEM) and specific surface area detection (BET) show that the enzyme treatment The latter samples became rougher and cracked as the specific surface area (SSA) increased. The higher calorific value of the 100 and 200 mg/g enzyme-treated samples increased from 17.8 MJ/kg to 18.9 MJ/kg and 19.3 MJ/kg, respectively. The durability and hardness of granules made from 200mg/g (optimal) enzyme treatment increased from 73.4% and 0.8N/ ^mm2 to 80.8% and 1.3N/ ^mm2 compared to granules made from untreated material . Kinetic analysis showed that the activation energy of 200 mg/g enzyme-treated pellets decreased from 45.5 KJ/mol to 34.2 KJ/mol in the first-order reaction model, and from 95.8 KJ/mol to 95.8 KJ/mol in the three-dimensional diffusion model. 77.8KJ/mol, thus, there are application possibilities in the field of processing solid biofuels from Ginkgo biloba residues treated with cellulase, and provide insights for better effective treatment of forest residues.

The above-mentioned embodiments only represent several embodiments of the present invention, and the descriptions thereof are specific and detailed, but should not be construed as a limitation on the scope of the patent of the present invention. It should be pointed out that for those skilled in the art, without departing from the concept of the present invention, several improvements can be made, which all belong to the protection scope of the present invention.

Claims (8)

1. An enzymolysis treatment method of ginkgo leaves is characterized by comprising the steps of grinding, sieving and drying the ginkgo leaves to obtain ginkgo leaf powder, soaking the ginkgo leaf powder in cellulase treatment liquid at room temperature, leaching enzymolysis residues of the ginkgo leaf powder through water leaching, and finally filtering and drying.

2. The method of claim 1, wherein the cellulase treatment solution is a 60% ethanol solution containing cellulase at a concentration of 100-200 mg/g.

3. The method of claim 2, wherein the cellulase-treated solution is a 60% ethanol solution containing cellulase at a concentration of 200 mg/g.

4. Use of the enzymatic hydrolysis treatment method of ginkgo leaves according to any one of claims 1 to 3 in the processing of solid biofuels.

5. A solid fuel particle of ginkgo leaf is characterized in that the solid fuel particle of ginkgo leaf is obtained by obtaining ginkgo leaf residue through the processing method of any one of claims 1 to 3 and then granulating the ginkgo leaf residue serving as a main raw material.

6. The method for preparing the ginkgo leaf solid fuel particles of claim 5, comprising the following steps:

(1) grinding folium Ginkgo with grinder, sieving, and drying at 45 deg.C for 48 hr to obtain folium Ginkgo powder;

(2) soaking the ginkgo leaf powder obtained in the step (1) in a 60% ethanol solution containing cellulase with the concentration of 100-200mg/g at room temperature for 24 hours, separating solid from liquid, adding 40g of deionized water into the solid at room temperature for 2 hours to leach enzymolysis residues of the ginkgo leaf powder, filtering the enzymolysis residues to obtain filter residues, drying the filter residues in an oven to obtain ginkgo leaf residues, and storing the ginkgo leaf residues in a sealed environment for later use;

(3) and (3) granulating the ginkgo leaf residues obtained in the step (2) to prepare granules.

7. The method of claim 6, wherein the moisture content of the ginkgo biloba leaves residue is adjusted to 10% or less before the granulation in the step (3).

8. The method for preparing ginkgo leaf solid fuel particles according to claim 6, wherein in the step (3), the granulation equipment is a single particle device with an inner diameter of 6.35mm and a length of 90 mm.

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