Biochar from Liquor Spent Grains and Its Application

Abstract

The present invention discloses a biochar of liquor lees and its application, and belongs to the technical field of recycling liquor byproducts. In order to realize the effective resource treatment of liquor lees byproducts, the present invention provides a biochar of liquor lees, comprising: the liquor lees are directly mixed with water after drying or mixed with water after crushing and screening, and pre-treated lees are obtained after azeotropic treatment, freezing and freeze-drying; the pre-treated lees are obtained after secondary carbonization. The present invention performs azeotropic treatment, freezing and freeze-drying treatment on the liquor lees, and uses continuous low-temperature pyrolysis and high-temperature pyrolysis to complete the secondary carbonization of the lees, which is beneficial to the formation of the initial pore size of the biochar and the improvement of the pore structure. The process operation is simple, the equipment requirements are low, the adsorption performance of the lees biochar in the post-treatment of liquor is enhanced, and the utilization value of the liquor lees is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of recycling liquor by-products, and particularly relates to liquor lees biochar and application thereof. Background Art

[0002] Liquor lees are the main by-products produced after fermentation and distillation of raw materials in the process of liquor brewing. As a major liquor brewing country, my country's annual output of liquor lees has reached 100 million tons. Due to its high water content, high acidity, and easy corruption and deterioration, improper stacking or untimely treatment of liquor lees will cause serious environmental pollution. However, liquor lees also contain rich substances such as cellulose, lignin, starch and protein. Effective resource utilization can not only reduce the environmental pollution problem of liquor lees, but also bring certain economic benefits. At present, the main treatment methods of liquor lees are agricultural composting, feed production and incineration and landfill, and the value utilization is not sufficient. Liquor lees are not only rich in biomass, but also the main dry matter bran shell has a structure similar to that of traditional charcoal raw material wood, which is an ideal carbon source for development and utilization.

[0003] Biochar is a carbonaceous material produced by high-temperature pyrolysis of biomass or organic waste in an anaerobic or anoxic environment. It has a stable pore structure, abundant surface functional groups (such as -COOH, -OH and -NH2) and a large specific surface area. It can be used as a high-quality energy source and soil conditioner, as well as a reducing agent, a slow-release fertilizer carrier and a carbon dioxide sequestration agent. It has been widely used in greenhouse gas emission reduction, water purification, heavy metal adsorption and soil improvement.

[0004] Liquor is a unique Chinese culture, mainly composed of water, ethanol and trace components, of which water and ethanol account for about 98%, and trace components account for 2%. These 2% trace components (alcohols, acids, esters and other substances) significantly affect the quality and style of liquor. In current winery production, the ethyl acetate content in the mash is relatively high due to various reasons, resulting in abnormal ethyl acetate indicators in the first-level and second-level wines obtained according to quantity and quality during the distillation process. In the existing traditional brewing process, the problem of excessive ethyl acetate content can be fundamentally solved by improving the structure of the mash and reshaping the traditional fermentation process, but this method has a long regulation cycle and it is difficult to predict the improvement results. Summary of the invention

[0005] In order to effectively recycle the byproducts of liquor waste, the present invention provides a liquor waste biochar, which exhibits certain adsorption performance for acetal and ethyl acetate in liquor. When adsorbing the original liquor, it can effectively reduce the content of ethyl acetate while ensuring that the ethyl caproate index is basically stable. In the present invention, the preparation of waste biochar is achieved by azeotropic treatment, freezing and freeze-drying of liquor waste, and based on a continuous secondary carbonization process. The volatilization and release of raw material components in low-temperature pyrolysis carbonization is conducive to the formation of the initial pore size of biochar, and the short-term high-temperature pyrolysis carbonization is easy to form a developed microporous structure, thereby enriching the pore structure of biochar.

[0006] The present invention provides a white wine lees biochar, and a preparation method thereof comprises the following steps:

[0007] A. After the liquor lees are dried, they are mixed with water, azeotropically treated, cooled and frozen, and then freeze-dried to obtain pre-treated lees;

[0008] B. The pre-treated spent grains obtained in step A are subjected to continuous secondary carbonization to obtain white wine spent grains biochar.

[0009] Among them, in the above-mentioned white wine lees biochar, in step A, after the white wine lees are dried, they are first crushed to no more than 80 meshes and then mixed with water.

[0010] Among them, in the above-mentioned white wine waste biochar, in step A, the mass ratio of the white wine waste (after drying) to water is 1:3-5.

[0011] Wherein, in the above-mentioned white wine waste biochar, in step A, the temperature of the azeotropic treatment is 90-110°C.

[0012] Wherein, in the above-mentioned white wine waste biochar, in step A, the time of the azeotropic treatment is 0.5 to 2 hours.

[0013] Wherein, in the above-mentioned white wine spent grains biochar, in step A, the cooling is cooling at room temperature for 5 to 30 minutes.

[0014] Wherein, in the above-mentioned white wine lees biochar, in step A, the freezing temperature is -15 to -30°C.

[0015] Wherein, in the above-mentioned white wine waste biochar, in step A, the freezing time is 2 to 5 hours.

[0016] Wherein, in the above-mentioned white wine lees biochar, in step A, the freeze-drying temperature is -50 to -60°C.

[0017] Wherein, in the above-mentioned white wine waste biochar, in step A, the freeze-drying time is 12 to 24 hours.

[0018] Among them, in the above-mentioned white wine spent grains biochar, in step B, the continuous secondary carbonization is to first heat the temperature from room temperature to 230-260°C for 15-30 minutes, keep the reaction for 0.5-2 hours, continue to heat the temperature to 400-500°C for 15-30 minutes, keep it for 1-4 hours, continue to heat the temperature to 700-900°C for 30-60 minutes, and keep it for 0.5-1 hour.

[0019] The present invention uses liquor waste as raw material, optimizes the process of preparing biochar, and makes the biochar show certain adsorption performance for acetal and ethyl acetate in liquor. Therefore, the present invention also provides the application of the liquor waste biochar in liquor adsorption.

[0020] Beneficial effects of the present invention:

[0021] The present invention utilizes liquor waste as a biomass carbon source, and performs azeotropic treatment, freezing and freeze-drying treatment on the liquor waste, and a continuous secondary carbonization process, so that the raw material is fully pyrolyzed, so that the obtained liquor waste biomass has a developed microporous structure and a rich pore structure, and the specific surface area of ​​the primary carbonization product is increased, and the specific surface area reaches 428m 2 / g, and exhibits certain adsorption performance for acetal and ethyl acetate in liquor, especially being able to effectively reduce the content of ethyl acetate while ensuring that the ethyl caproate index is basically stable; and the present invention does not require any external chemical reagents, the production process is environmentally friendly and clean, and the obtained product will not introduce impure ions in the post-treatment of liquor, thereby maintaining the purity of the liquor.

[0022] The present invention provides a valuable biochar product while reducing environmental pollution caused by waste dregs. The process is simple, no high-temperature pyrolysis protection gas, i.e., pressure gas cylinder, is used, the equipment requirements are low, the production safety is high, and it has certain environmental and economic values. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a characterization diagram of the spent grains biochar obtained in Example 1; wherein a is a microscopic morphology diagram, b is a N2 isotherm adsorption-desorption curve, and c is a pore size distribution curve.

[0024] Figure 2 This is a characterization diagram of the spent grains biochar prepared in comparative example 1; wherein a is a microscopic morphology diagram, b is a N2 isothermal adsorption-desorption curve, and c is a pore size distribution curve.

[0025] Figure 3 This is the characterization diagram of the spent grains biochar prepared in comparative example 3, where a is the microscopic morphology diagram, b is the N2 isothermal adsorption-desorption curve, and c is the pore size distribution curve. DETAILED DESCRIPTION

[0026] Specifically, a method for preparing white wine lees biochar comprises the following steps:

[0027] A. After the liquor lees are dried, they are mixed with water or crushed and sieved and then mixed with water, azeotropically treated, cooled and frozen, and then freeze-dried to obtain pre-treated lees;

[0028] B. The pre-treated spent grains obtained in step A are subjected to continuous secondary carbonization to obtain white wine spent grains biochar.

[0029] In the present invention, the mesh number of the liquor lees is controlled to be no more than 80 meshes, and the mass ratio of the lees to water is 1:3-5. After azeotropy, the lees are gelatinized, the starch in the lees absorbs water and expands when heated, the molecular crystalline structure is destroyed to form a gel, and the suspension becomes viscous and does not need to be filtered. In step A, the temperature of the azeotropic treatment is 90-110° C.; the time of the azeotropic treatment is 0.5-2 hours.

[0030] In the present invention, the shorter the freezing time, the smaller and more uniform the ice crystals formed, and the more stable and dense structure. Therefore, the present invention adopts a short-term freezing directly after a short room temperature drop, rather than a long-term storage at room temperature. In step A, the cooling is room temperature cooling for 10 minutes; the freezing temperature is -15 to -30°C; and the freezing time is 2 to 5 hours.

[0031] According to the test, if low temperature drying is used after gelatinization, the gel structure in the waste will be destroyed and the whole becomes burnt and hard; while the pre-treated waste after freeze drying is loose and soft as a whole, and the structure does not collapse significantly. Therefore, the present invention freeze-dries the frozen material at -50 to -60°C for 12 to 24 hours.

[0032] The experiment showed that if the lees were only carbonized once, the resulting biochar had a weak adsorption capacity for esters and alcohols in the original liquor; however, after continuous secondary carbonization: first raising the temperature from room temperature to 230-260°C for 15-30 minutes, maintaining the reaction for 0.5-2 hours, continuing to raise the temperature to 400-500°C for 15-30 minutes, maintaining for 1-4 hours, and continuing to raise the temperature to 700-900°C for 30-60 minutes, maintaining for 0.5-1 hour, the resulting biochar showed a more obvious adsorption capacity for acetal and ethyl acetate in liquor.

[0033] The present invention is further described in detail below by way of examples, but the protection scope of the present invention is not limited to the scope of the examples.

[0034] Example 1

[0035] (1) After the liquor lees are dried, 20 g of dry lees (not crushed) are weighed and mixed with 90 mL of deionized water, stirred at 100° C. for 1 h, cooled at room temperature for 10 min, and then frozen at -24° C. for 2 h, and freeze-dried to obtain the pretreated lees;

[0036] (2) The pretreated spent grains obtained in step (1) are placed in a muffle furnace, the temperature is raised from room temperature to 250°C for reaction for 1 hour, the temperature is then raised to 450°C for carbonization for 2 hours, and the temperature is further raised to 800°C for high-temperature secondary carbonization for 0.5 hour to obtain spent grains biochar.

[0037] Experimental results: The specific surface area of ​​the obtained biochar is 428m 2 / g, micropore surface area 356m 2 / g, pore volume 0.09cm 3 / g, pore diameter 3.05nm. In the adsorption experiment of Luzhou-flavor raw liquor, the results of gas phase analysis show that compared with the raw liquor sample, the content of acetal and ethyl acetate in the adsorbed liquor sample is significantly reduced, and the average adsorption amount of biochar is 66.49mg / g and 1023.41mg / g respectively (see Table 1 for the quantitative analysis results of alcohol and ester). The spent lees biochar shows obvious selective adsorption for ethyl acetate; and when the spent lees biochar adsorbs liquor, in addition to the adsorption effect, it also has a certain aging effect, which may cause trace components such as ethyl lactate and isopentanol to change slightly due to their own reactions.

[0038] Example 2

[0039] (1) After the liquor lees are dried, they are crushed and passed through an 80-mesh sieve. 20 g of the dried lees are weighed and mixed with 80 mL of deionized water. The mixture is stirred at 100° C. for 1 h. After cooling at room temperature for 10 min, the mixture is frozen at −24° C. for 2.5 h. The pretreated lees are obtained by freeze-drying.

[0040] (2) The pretreated spent grains obtained in step (1) are placed in a muffle furnace, the temperature is raised from room temperature to 250°C for reaction for 1 hour, the temperature is then raised to 450°C for carbonization for 2 hours, and the temperature is further raised to 800°C for high-temperature secondary carbonization for 0.5 hour to obtain spent grains biochar.

[0041] Experimental results: The specific surface area of ​​the obtained waste slag biochar is 384m 2 / g, micropore surface area 308m 2 / g, pore volume 0.06cm 3 / g, pore diameter 3.41nm. In the adsorption experiment of Luzhou-flavor original liquor, the gas phase analysis results show that compared with the original liquor sample, the content of acetal and ethyl acetate in the adsorbed liquor sample is significantly reduced, and the average adsorption amount of biochar is 39.49mg / g and 692.89mg / g respectively (see Table 1 for the quantitative analysis results of alcohol and ester).

[0042] Comparative Example 1

[0043] (1) After the liquor lees are dried (without being crushed), they are placed in a muffle furnace and heated from room temperature to 250°C for 1 h, then heated to 450°C for carbonization for 2 h, and then heated to 800°C for secondary high-temperature carbonization for 0.5 h to obtain the lees biochar.

[0044] Experimental results: The specific surface area of ​​the waste slag biochar is 313m 2 / g, micropore surface area 263m 2 / g, pore volume 0.06cm 3 / g, pore diameter 3.06nm. In the adsorption experiment of Luzhou-flavor original liquor, the gas phase analysis results show that compared with the original liquor sample, the content of acetal and ethyl acetate in the adsorbed liquor sample is reduced to a certain extent, and the average adsorption amount of biochar is 35.89mg / g and 552.38mg / g, respectively, which is about 54% of Example 1 (see Table 1 for alcohol ester quantitative analysis results).

[0045] In terms of microstructure, compared with Comparative Example 1 ( Figure 2 ), after azeotropy, freezing and freeze-drying, the obtained Example 1 ( Figure 1 ) The surface roughness increased significantly, and the pore structure became richer, which was consistent with the results of nitrogen adsorption and desorption characterization and liquor adsorption experiments. In addition, in the changes of acetal and ethyl acetate content, the parallel sample results of Comparative Example 1 had certain differences, while those of Example 1 were basically consistent. This situation also occurred in Example 2 and Comparative Example 2, indicating that the activity of biochar only subjected to secondary carbonization was not uniform, and the azeotropic, freezing and freeze-drying treatments could effectively improve the uniformity of the activity of secondary carbonized biochar.

[0046] Comparative Example 2

[0047] (1) The liquor lees were dried, crushed, and passed through an 80-mesh sieve. The lees were placed in a muffle furnace and heated from room temperature to 250°C for 1 h. The temperature was then raised to 450°C for carbonization for 2 h. The temperature was then further raised to 800°C for secondary high-temperature carbonization for 0.5 h to obtain the lees biochar.

[0048] Experimental results: The specific surface area of ​​the biochar obtained was 318m 2 / g, micropore surface area 263m 2 / g, pore volume 0.05cm 3 / g, pore diameter 3.41nm. In the adsorption experiment of Luzhou-flavor original liquor, the gas phase analysis results show that compared with the original liquor sample, the content of acetal and ethyl acetate in the adsorbed liquor sample is reduced to a certain extent, and the average adsorption amount of biochar is 15.97mg / g and 329.74mg / g, respectively, which is 50% lower than that of Example 2 (see Table 1 for the quantitative analysis results of alcohol esters).

[0049] Comparative Example 3

[0050] (1) After the liquor lees are dried (without being crushed), they are placed in a muffle furnace and heated from room temperature to 250°C for 1 h, and then heated to 450°C for carbonization for 2 h to obtain lees biochar.

[0051] Experimental results: The BET specific surface area of ​​the obtained waste slag biochar is 95m 2 / g, micropore surface area 46m 2 / g, pore volume 0.03cm 3 / g, pore diameter 3.41nm. In the adsorption experiment of Luzhou-flavor original liquor, the gas phase analysis results show that: compared with the original liquor sample, the ethyl acetate content in the adsorbed liquor sample is slightly lower, and the average adsorption amount of biochar is about 149.85mg / g (see Table 1 for alcohol ester quantitative analysis results).

[0052] Table 1 Quantitative analysis results of alcohol esters

[0053]

[0054] Note: 1. The value unit in the table is mg / 100mL; 2. Biochar dosage 1wt‰, wine sample 200g (about 225mL), 18℃, 24h.

Claims

1. Liquor waste biochar, characterized by: The preparation method comprises the following steps: A. After the liquor lees are dried, they are mixed with water, azeotropically treated, cooled and frozen, and then freeze-dried to obtain pre-treated lees; B. The pre-treated spent grains obtained in step A are subjected to continuous secondary carbonization to obtain white wine spent grains biochar; In step A, the freezing temperature is -15 to -30°C; In step B, the continuous secondary carbonization is firstly to heat up from room temperature to 230-260°C for 15-30min, keep the reaction for 0.5-2h, continue to heat up to 400-500°C for 15-30min, keep it for 1-4h, continue to heat up to 700-900°C for 30-60min, keep it for 0.5-1h.

2. The white wine lees biochar according to claim 1, characterized in that: In step A, after the liquor lees are dried, they are first crushed to no more than 80 meshes and then mixed with water.

3. The white wine lees biochar according to claim 1 or 2, characterized in that: In step A, the mass ratio of the liquor waste to water is 1:3-5.

4. The white wine lees biochar according to claim 1 or 2, characterized in that: In step A, the temperature of the azeotropic treatment is 90-110° C.; in step A, the time of the azeotropic treatment is 0.5-2 h.

5. The white wine lees biochar according to claim 1 or 2, characterized in that: In step A, the cooling is cooling at room temperature for 5 to 30 minutes.

6. The white wine lees biochar according to claim 1 or 2, characterized in that: In step A, the freezing time is 2 to 5 hours.

7. The white wine lees biochar according to claim 1 or 2, characterized in that: In step A, the freeze-drying temperature is -50 to -60°C.

8. The white wine lees biochar according to claim 1 or 2, characterized in that: In step A, the freeze-drying time is 12 to 24 hours.

9. Use of the liquor waste biochar according to any one of claims 1 to 8 in liquor adsorption.

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