Hydrothermal liquefaction method for Sb-rich pennisetum sinese

Abstract

The invention belongs to the field of environmental protection, and particularly discloses a hydrothermal liquefaction method of Sb-rich pennisetum sinese, which comprises the following steps: 1) hydrothermal liquefaction: uniformly mixing pennisetum sinese and a proper amount of pure water, pouring the mixture into a reaction kettle, installing equipment, purging with nitrogen, emptying air in the kettle, turning on a magnetic stirrer, and stirring to react for 20-60 minutes at the reaction temperature of 220-300 DEG C to obtain a hydrothermal liquefaction product; 2) product separation: S1) in the hydrothermal liquefaction product obtained in the step 1), collecting a gas product with a gas collection bag, and sending the gas product to gas chromatography to determine the components of the gas product; s2, separating solid residues from a liquid product by using a vacuum filter, and extracting a solid phase by using ethyl acetate through filter paper until filtrate becomes colorless; s3, drying the solid residues in a drying oven to obtain a product charcoal; S4, separating an organic phase in filtrate through a separating funnel, and then concentrating by using a rotary evaporator; s5, evaporating the ethyl acetate solvent to obtain the product bio-oil; the method can provide an industrial application scheme for the development of a phytoremediation technology.

Description

Technical Field

[0001] The present invention belongs to the field of environmental protection, and specifically discloses a method for hydrothermal liquefaction of Sb-rich Pennisetum giganteum. Background Art

[0002] Antimony (Sb) and its compounds are important raw materials indispensable for modern industrial production, and also play an important role in the medical field. However, Sb and its compounds are substances with genotoxicity and carcinogenic effects on the human body. Currently, the main soil remediation methods include physical remediation methods, chemical remediation methods, and biological remediation methods. Phytoremediation has broad application prospects in removing soil heavy metal pollution due to its low cost and environmental friendliness.

[0003] "How to deal with the final products of phytoremediation" has become an issue that cannot be ignored. Since the plant harvests are enriched with a large amount of heavy metals and belong to one of the hazardous wastes, they need to be handled with caution. If not handled properly, it may lead to the re-release of heavy metals into the environment. Summary of the Invention

[0004] To solve the above problems, the present invention discloses a method for hydrothermal liquefaction of Sb-rich Pennisetum giganteum.

[0005] The present invention includes the following technical solutions: A method for hydrothermal liquefaction of Sb-rich Pennisetum giganteum, comprising the following steps: 1) Hydrothermal liquefaction: Mix Pennisetum giganteum and an appropriate amount of pure water evenly, pour them into a reaction kettle, install the equipment, purge with nitrogen, evacuate the air in the kettle, turn on the magnetic stirrer and stir for 20 - 60 min, and react at a reaction temperature of 220 - 300 °C to obtain a hydrothermal liquefaction product; 2) Product separation: S1 In the hydrothermal liquefaction product obtained in step 1), the gas product is collected with a gas collection bag and sent to a gas chromatograph to determine its composition; S2 Use a vacuum filter to separate the solid residue and the liquid product, and then extract the solid phase with ethyl acetate through filter paper until the filtrate becomes colorless; S3 Dry the solid residue in an oven to obtain the product biochar, S4 Separate the organic phase in the filtrate through a separating funnel, and then concentrate it using a rotary evaporator; S5 After evaporating the ethyl acetate solvent, the product bio-oil is obtained.

[0006] Furthermore, in the above method for hydrothermal liquefaction of Sb-rich Pennisetum giganteum, the mass-volume ratio of the Pennisetum giganteum to the pure water in step 1) is 1:30 g / mL.

[0007] Further, in the above method for hydrothermal liquefaction of Sb-rich Pennisetum giganteum, the purity of nitrogen in step 1) is ≥99.9%, and the purging time is ≥5 min.

[0008] Further, in the above method for hydrothermal liquefaction of Sb-rich Pennisetum giganteum, the stirring speed in step 1) is 500 rpm.

[0009] Further, in the above method for hydrothermal liquefaction of Sb-rich Pennisetum giganteum, the reaction time in step 1) is 60 min, and the reaction temperature is 280 °C.

[0010] Further, in the above method for hydrothermal liquefaction of Sb-rich Pennisetum giganteum, the pressure in the reaction kettle in step 1) is controlled between 0 - 2 Mpa.

[0011] Further, in the above method for hydrothermal liquefaction of Sb-rich Pennisetum giganteum, in step S3, the oven temperature is 105 °C, and the drying time is 12 h.

[0012] Further, in the above method for hydrothermal liquefaction of Sb-rich Pennisetum giganteum, the temperature in the rotary evaporator is 45 °C.

[0013] Further, in the above method for hydrothermal liquefaction of Sb-rich Pennisetum giganteum, the equipment in step 1) includes a reaction kettle, a water pump, a PID temperature control console, a pressure gauge, a magnetic stirrer, a thermometer, a pressure reducing valve, a nitrogen cylinder, and a water tank; the reaction kettle is a cylindrical container, the magnetic stirrer is installed in the reaction kettle, and the thermometer is also installed in the reaction kettle; the pressure gauge is installed on the top of the reaction kettle; the PID temperature control console is connected to the reaction kettle through a wire; the water pump is arranged on one side of the reaction kettle, the water tank is arranged on the other side of the reaction kettle, and the water pump, the reaction kettle, and the water tank are connected through pipelines; the nitrogen cylinder is connected to the reaction kettle through a pressure reducing valve.

[0014] Further, the present invention discloses a biomass product prepared by the method described in any one of the above.

[0015] Further, the above biomass product is biochar or bio-oil.

[0016] Compared with the prior art, the present invention has the following outstanding beneficial effects: The present invention takes Pennisetum giganteum, which has a large yield and fast growth rate, as the object. After analyzing the liquefaction characteristics of the products after its remediation, a hydrothermal liquefaction method for Pennisetum giganteum is provided, which can realize the harmless and energy-based treatment of the remediation plants and provide an industrial application solution for the development of phytoremediation technology. Specifically, the present invention finds that the optimal conditions for the hydrothermal liquefaction of Pennisetum giganteum are 280 °C and 60 min; the temperature and reaction time have a greater impact on the bio-oil yield. With the increase of temperature and reaction time, the bio-oil yield first increases and then decreases. The initial pressure of the reaction kettle has little effect on the liquefied products, and in order to achieve higher economic benefits, the reaction kettle can not be pressurized. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the hydrothermal liquefaction experiment system; Figure 2 Effect of different temperatures on the liquefied products of Pennisetum giganteum; Figure 3 Effect of different reaction times on the liquefied products of Pennisetum giganteum; Figure 4 Effect of different initial pressures on the hydrothermal liquefied products; Figure 5 Effect of different temperatures on the migration and distribution of Sb; Figure 6 Effect of different reaction times on the migration and distribution of Sb; Figure 7 Effect of different pressures on the migration and distribution of Sb. DETAILED DESCRIPTION OF THE INVENTION

[0018] A method for hydrothermal liquefaction of Sb-rich Pennisetum giganteum includes the following steps: 1) Hydrothermal liquefaction: Mix Pennisetum giganteum and an appropriate amount of pure water evenly and pour them into the reaction kettle. Install the equipment, purge with nitrogen to exhaust the air in the kettle, turn on the magnetic stirrer and stir for 20 - 60 min, and the reaction temperature is 220 - 300 °C to obtain the hydrothermal liquefied products; 2) Product separation: S1 In the hydrothermal liquefied products obtained in step 1), the gas products are collected with a gas collection bag and sent to a gas chromatograph to determine their components; S2 Use a vacuum filter to separate the solid residue and the liquid products, and then extract the solid phase with ethyl acetate through filter paper until the filtrate becomes colorless; S3 Dry the solid residue in an oven to obtain the product biochar, S4 Separate the organic phase in the filtrate through a separating funnel, and then concentrate it using a rotary evaporator; S5 After evaporating the ethyl acetate solvent, the product bio-oil is obtained.

[0019] Further, in the step 1), the mass-volume ratio of the Pennisetum giganteum and pure water is 1:30 g / mL; the stirring speed in the step 1) is 500 rpm; the reaction time in the step 1) is 60 min, the reaction temperature is 280 °C, and the pressure in the reaction kettle in the step 1) is controlled between 0 and 2 Mpa; in the step S3, the oven temperature is 105 °C and the drying time is 12 h; the temperature in the rotary evaporator is 45 °C; the equipment in the step 1) is as Figure 1 shown, including a reaction kettle 1, a water pump 2, a PID temperature control console 3, a pressure gauge 4, a magnetic stirrer 5, a thermometer 6, a pressure reducing valve 7, a nitrogen cylinder 8, and a water tank 9; the reaction kettle 1 is a cylindrical container, the magnetic stirrer 5 is installed in the reaction kettle 1, and the thermometer 6 is also installed in the reaction kettle 1; the pressure gauge 4 is installed on the top of the reaction kettle 1; the PID temperature control console 3 is connected to the reaction kettle 1 through a wire; the water pump 2 is arranged on one side of the reaction kettle 1, the water tank 9 is arranged on the other side of the reaction kettle 1, and the water pump 2, the reaction kettle 1 and the water tank 9 are connected through pipelines; the nitrogen cylinder 8 is connected to the reaction kettle 1 through the pressure reducing valve 7.

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. Embodiment

[0021] 1. Experimental study on the hydrothermal liquefaction characteristics of Pennisetum giganteum By controlling the reaction temperature and reaction time factors, the hydrothermal liquefaction characteristics of Pennisetum giganteum are studied, and its optimal reaction temperature and reaction time are determined.

[0022] (1) Selection of experimental materials: Since the metal contents adsorbed by different parts of plants are inconsistent, to ensure the accuracy of the experiment and make the Sb concentration in each group of Pennisetum giganteum consistent, the experiment uses a mixture of normally grown and dried Pennisetum giganteum (1 g) and Sb2O3 (0.01 g) as the raw material, that is, 0.01 g of Sb2O3 is adsorbed in 1 g of Pennisetum giganteum.

[0023] (2) Selection of experimental equipment: The experiment mainly uses a magnetic stirring high-pressure reaction kettle manufactured by Dalian Tongchan High-Pressure Reaction Kettle Manufacturing Co., Ltd., a rotary evaporator manufactured by Henan Ruide Instrument Co., Ltd., and a digital display constant temperature water bath (HH-1) manufactured by Jiangnan Instrument Factory in Jintan City, Jiangsu Province.

[0024] (3)Experimental procedure: First, 1 g of Pennisetum giganteum and 30 mL of pure water were mixed evenly and poured into the reactor. Then, the equipment was assembled and purged with nitrogen with a purity greater than 99.9% for 5 min to ensure that the air in the reactor was completely exhausted. Finally, the magnetic stirrer was set to 500 rpm, and the final reaction temperature (220 - 300 °C) and reaction time (20 - 60 min) were adjusted to the target parameters, and then the experiment was started.

[0025] (4)Product separation method: In the hydrothermal liquefaction products, the gas products were collected with a gas collection bag and sent to a gas chromatograph to determine their composition. Then, a vacuum filter was used to separate the solid residue and liquid products. Next, the solid phase was extracted with ethyl acetate through a filter paper until the filtrate became colorless. The solid residue was dried in an oven at 105 °C for 12 h to obtain biochar. Subsequently, the organic phase in the filtrate was separated by a separatory funnel, and then concentrated using a rotary evaporator at 45 °C. Finally, after evaporating the ethyl acetate solvent, the obtained organic product was regarded as bio-oil.

[0026] 2. Results and Analysis (1)Reaction temperature: The influence of reaction temperature on the liquefaction products of Pennisetum giganteum is as Figure 2 shown: At 220 °C, most of the residue after liquefaction of Pennisetum giganteum accounted for 45.76%, the oil yield was relatively low at 17.15%, and other products accounted for 37.09%. This is mainly because the reaction temperature is relatively low and the biomass is not completely degraded. As the liquefaction temperature rises from 220 °C to 300 °C, the bio-oil yield first increases and then decreases, and the yield is the largest at 280 °C, which is 22.8%. Based on the above results, in the following liquefaction study, the temperature was set at 280 °C.

[0027] (2)Reaction time: The distribution of Pennisetum giganteum products under different liquefaction times is as Figure 3 shown. Under the same conditions, as the reaction time increases from 20 minutes to 100 minutes, the bio-oil yield first increases from 13.2% to 22.8%. However, after continuing to increase the reaction time after 60 minutes, the yield of bio-oil begins to decline. At 100 minutes, the bio-oil yield is only 16.95%, while the ash yield shows the opposite trend. Based on the above results, the optimal reaction time for the hydrothermal liquefaction of Pennisetum giganteum is 60 minutes.

[0028] (3)Initial pressure of the reactor: The influence of the initial pressure of the reactor on the hydrothermal liquefaction products is as Figure 4 shown. It can be seen from the figure that under the conditions of a reaction temperature of 280 °C and a reaction time of 60 minutes, changing the initial reaction pressure has little effect on the liquefaction products. When the initial reaction pressure increases from 0 to 2 Mpa, the oil yield is between 19.05 - 22.8%, the ash yield is between 30.15% - 31.65%, and the yield of other products is between 45.15 - 50.05%.

[0029] (4) Influence of Liquefaction Conditions on Sb Migration As can be seen from Figure 5 , 6, and 7, after hydrothermal liquefaction of Sb-rich Pennisetum giganteum, Sb is mainly enriched in the ash, with a proportion of less than 10% in the liquid phase. Increasing the temperature is beneficial to the migration of Sb to the solid phase. When the reaction temperature increases from 220 °C to 300 °C, the solid-phase content of Sb increases from 90.51% to 94.04%. The reaction time and the initial pressure of the autoclave have little effect on the Sb distribution.

[0030] 3. Conclusions The optimal conditions for hydrothermal liquefaction of Pennisetum giganteum are 280 °C and 60 minutes. Temperature and reaction time have a greater impact on the bio-oil yield. With the increase of temperature and reaction time, the bio-oil yield first increases and then decreases. The initial pressure of the autoclave has little effect on the liquefaction products. In order to achieve higher economic benefits, the autoclave can not be pressurized.

[0031] The above are only several limited preferred embodiments of the present invention, and the description is relatively specific and detailed. However, it should not be construed as a limitation on the scope of the present invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can be made, and these all belong to the protection scope of the present invention.

Claims

1. A method for hydrothermal liquefaction of giant miscanthus rich in Sb, characterized in that, It includes the following steps: 1) Hydrothermal liquefaction: Mix giant miscanthus and an appropriate amount of pure water evenly, pour them into a reaction kettle, install the equipment, purge with nitrogen, evacuate the air in the kettle, turn on the magnetic stirrer and stir for 20 - 60 min, and obtain the hydrothermal liquefaction product at a reaction temperature of 220 - 300 °C; 2) Product separation: S1 In the hydrothermal liquefaction product obtained in step 1), the gas product is collected with a gas collection bag and sent to a gas chromatograph to determine its composition; S2 Use a vacuum filter to separate the solid residue and the liquid product, and then extract the solid phase with ethyl acetate through filter paper until the filtrate becomes colorless; S3 Dry the solid residue in an oven to obtain the product biochar, S4 Separate the organic phase in the filtrate through a separatory funnel, and then concentrate it using a rotary evaporator; S5 After evaporating the ethyl acetate solvent, obtain the product bio-oil.

2. A method for hydrothermal liquefaction of Sb-rich Pennisetum giganteum, according to claim 1, characterized in that In step 1), the mass-volume ratio of the giant miscanthus to the pure water is 1:30 g / mL.

3. A method for hydrothermal liquefaction of Sb-rich Pennisetum giganteum, according to claim 1, characterized in that In step 1), the purity of the nitrogen is ≥99.9%, and the purging time is ≥5 min.

4. A method for hydrothermal liquefaction of Sb-rich Pennisetum giganteum, according to claim 1, characterized in that In step 1), the stirring speed is 500 rpm.

5. A method for hydrothermal liquefaction of rich-Sb giant miscanthus grass according to claim 1, characterized in that, In step 1), the reaction time is 60 min, the reaction temperature is 280 °C, and the pressure in the reaction kettle in step 1) is controlled between 0 - 2 Mpa.

6. A method for hydrothermal liquefaction of Sb-rich giant miscanthus grass according to claim 1, characterized in that, In step S3, the oven temperature is 105 °C, and the drying time is 12 h.

7. A method for hydrothermal liquefaction of rich-Sb giant miscanthus grass according to claim 1, characterized in that The temperature in the rotary evaporator is 45 °C.

8. A method for hydrothermal liquefaction of Sb-rich Pennisetum giganteum, according to claim 1, characterized in that The equipment in step 1) includes a reaction kettle (1), a water pump (2), a PID temperature control console (3), a pressure gauge (4), a magnetic stirrer (5), a thermometer (6), a pressure reducing valve (7), a nitrogen cylinder (8), and a water tank (9); the reaction kettle (1) is a cylindrical container, the magnetic stirrer (5) is installed in the reaction kettle (1), and the thermometer (6) is also installed in the reaction kettle (1); the pressure gauge (4) is installed on the top of the reaction kettle (1); the PID temperature control console (3) is connected to the reaction kettle (1) through a wire; the water pump (2) is arranged on one side of the reaction kettle (1), the water tank (9) is arranged on the other side of the reaction kettle (1), and the water pump (2), the reaction kettle (1) and the water tank (9) are connected through pipelines; the nitrogen cylinder (8) is connected to the reaction kettle (1) through a pressure reducing valve (7).

9. A biomass product, characterized in that, Prepared by the method according to any one of claims 1 - 8.

10. The biomass product according to claim 9, characterized in that, The biomass product is biochar or bio-oil.

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