Vinasse activated carbon and preparation method thereof

Abstract

The invention discloses vinasse activated carbon and a preparation method thereof. The preparation method comprises the following steps: S1, drying and crushing vinasse, adding wine brewing wastewater, mixing, carrying out hydrothermal carbonization, filtering, washing and drying to obtain hydrothermal carbon; s2, adding an activating agent into the hydrothermal carbon in the S1 for dipping, and drying to obtain dipped hydrothermal carbon; s3, performing high-temperature activation on the soaked hydrothermal carbon in the step S2, cooling, washing and drying to obtain the hydrothermal carbon. The wine brewing wastewater is used for hydrothermal carbonization, the yield of activated carbon can be increased, the adsorption performance of the activated carbon can be improved, and the method is low in production cost, environmentally friendly, high in resource utilization rate and good in industrial application prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of biomass activated carbon preparation, and particularly relates to a distiller's grains activated carbon and a preparation method thereof. Background Art

[0002] Activated carbon has a large specific surface area and a developed pore structure, and is an excellent adsorbent, catalyst or carrier. Activated carbon is widely used in sewage treatment and gas purification, and can adsorb heavy metal ions and organic pollutants. In the field of catalytic energy storage, it can be used as a catalyst carrier, supercapacitor, etc. Activated carbon is an inorganic material with great application prospects. As the main by-product of the brewing industry, distiller's grains have a high acidity and are prone to spoilage, and are often used to produce low-value-added products such as feed and culture media. The organic wastewater in the brewing industry contains various organic substances such as alcohols, esters, acids, and aldehydes, which cause great environmental pollution and high treatment costs. Directly using waste biomass materials to prepare high-value-added activated carbon can improve resource utilization rate and reduce production costs.

[0003] The preparation method of biomass activated carbon is mainly divided into two stages: carbonization and activation. Biomass is carbonized at high temperature or under hydrothermal conditions, and then activated with water vapor, phosphoric acid, potassium hydroxide, zinc chloride, etc. For example, the Chinese patent application with the publication number CN109734089A discloses a preparation method of high specific surface area distiller's grains activated carbon, which carbonizes distiller's grains at high temperature. The hydrothermal carbonization method has lower energy consumption, less pollution, and higher carbonization product yield, and has greater application prospects. The Chinese patent application with the publication number CN115321536A discloses a treatment process and treatment system for preparing shaped activated carbon by hydrothermal carbonization of high-water-content organic waste. The high-water-content organic waste is crushed and then added with a certain amount of water to be converted into inorganic carbon through hydrothermal reaction, and then an activator is added to prepare activated carbon at high temperature. The wastewater in the high-water-content waste raw material of this method will seriously affect the transportation cost, and an appropriate amount of clear water needs to be supplemented according to the water content of the waste before the hydrothermal reaction. In addition, the main disadvantage of the conventional hydrothermal method is that it will produce a large amount of organic wastewater that is difficult to treat. The preparation of biomass activated carbon can also directly mix biomass with an activator for one-step carbonization and activation, but the performance of the activated carbon prepared by one-step carbonization and activation is poor. Therefore, there is an urgent need to develop a preparation method of biomass activated carbon with low cost and high yield to improve the adsorption performance of activated carbon. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to reduce the production cost of distiller's grains activated carbon, improve the yield and adsorption performance of activated carbon, in view of the characteristics of the biomass activated carbon production process and the waste by-products of the brewing industry. The present invention provides a distiller's grains activated carbon and a preparation method thereof, which have low production cost, high resource utilization rate, and the generated waste by-products are easy to treat, and the prepared distiller's grains activated carbon has good adsorption performance.

[0005] To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0006] A preparation method of distiller's grains activated carbon, comprising the following steps:

[0007] S1. Dry and crush the distiller's grains, add brewing wastewater and mix for hydrothermal carbonization, filter, wash and dry to obtain hydrothermal carbon;

[0008] S2. Add an activator to the hydrothermal carbon in S1 for impregnation and drying to obtain the impregnated hydrothermal carbon;

[0009] S3. High-temperature activate the impregnated hydrothermal carbon in S2 under the protection of inert gas or in a vacuum environment, cool, wash and dry to obtain the product.

[0010] The brewing wastewater of the present invention contains more alcohols, acids, and esters, which have a high solubility in the condensation of biomass hydrothermal reactions to produce small molecule compounds. After mixing with distiller's grains and performing hydrothermal carbonization, not only can the recycling of brewing wastewater and distiller's grains be realized, but also the yield can be synergistically improved and the adsorption performance of the activated carbon can be enhanced. In addition, the wastewater after multiple hydrothermal reactions has a high concentration of organic matter and is easy to be reprocessed and recycled, solving the problem that a large amount of organic wastewater produced by the conventional hydrothermal method is difficult to treat.

[0011] In a preferred embodiment of the present invention, the brewing wastewater in S1 is one or a mixture of bottom pan water or yellow water during the brewing process; preferably yellow water.

[0012] Yellow water is a brownish-yellow liquid with a special smell produced during the brewing of white liquor, containing more alcohols, acids, and esters, and having an acidic pH value. Yellow water mainly includes: 70wt% - 80wt% of water, 3 - 5g / L of acid substances, 2wt% - 5wt% of alcohol substances, 0.1 - 0.3g / L of ester substances, and 1 - 3g / L of sugar substances.

[0013] Compared with water and hydrothermal reaction wastewater, using brewing wastewater in the present invention can not only improve the yield of activated carbon, but also enhance the adsorption performance of activated carbon.

[0014] In a preferred embodiment of the present invention, the filtrate obtained by filtration in S1 can be mixed with the dried and crushed distiller's grains again for hydrothermal carbonization, and can be reused 1 - 5 times.

[0015] The present invention can not only synchronously treat brewing wastewater, but also the filtrate after hydrothermal carbonization can be reused, solving the problem that a large amount of organic wastewater produced by the existing hydrothermal reaction is difficult to treat. Repeated reuse can also increase the organic matter concentration of the brewing wastewater for extracting by-products such as acetic acid, lactic acid, and heavy oil.

[0016] In a preferred embodiment of the present invention, the temperature of the hydrothermal carbonization in S1 is 160 - 200 °C, and the time is 6 - 48 h.

[0017] In the prior art, the hydrothermal carbonization temperature usually adopted is higher than 190 °C. However, the present invention finds that the increase in the hydrothermal temperature will lead to an increase in the degree of hydrothermal condensation. By adopting a lower hydrothermal carbonization temperature, the present invention can improve the yield of activated carbon.

[0018] In a preferred embodiment of the present invention, the activating agent in S2 is one or more of phosphoric acid, potassium dihydrogen phosphate, potassium carbonate, and potassium hydroxide.

[0019] In a preferred embodiment of the present invention, when the activating agent is phosphoric acid or potassium dihydrogen phosphate, the mass ratio of the activating agent to the hydrothermal carbon is 2.0 - 4.0; preferably, the mass ratio of the activating agent to the hydrothermal carbon is 2.0 - 3.0.

[0020] In a preferred embodiment of the present invention, when the activating agent is potassium carbonate or potassium hydroxide, the mass ratio of the activating agent to the hydrothermal carbon is 3.0 - 5.0; preferably, the mass ratio of the activating agent to the hydrothermal carbon is 3.0 - 4.0.

[0021] The present invention innovates the activation process parameters for the hydrothermal carbonization reaction of distillers' grains and brewing wastewater, and further improves the yield and adsorption performance of activated carbon.

[0022] When the activating agent is potassium hydroxide and potassium carbonate, the methylene blue adsorption capacity of the prepared activated carbon can be significantly improved, and the yield of the activated carbon is lower than that of the activated carbon prepared by using phosphoric acid or potassium dihydrogen phosphate as the activating agent.

[0023] In a preferred embodiment of the present invention, the volume - weight ratio of the brewing wastewater to the dried distillers' grains in S1 is 5 - 20 mL / g, preferably 5 - 15 mL / g.

[0024] In a preferred embodiment of the present invention, the temperature of the high - temperature activation in S3 is 600 - 800 °C, and the activation time is 30 - 90 min; preferably, when the activating agent is phosphoric acid or potassium dihydrogen phosphate, the activation temperature is 600 - 700 °C; when the activating agent is potassium carbonate or potassium hydroxide, the activation temperature is 700 - 800 °C.

[0025] Preferably, in S1, the distillers' grains are crushed to 100 - 300 meshes.

[0026] Preferably, the mass concentration of the phosphoric acid and the potassium dihydrogen phosphate is 20 - 60 wt%, preferably 30 - 50 wt%. The mass concentration of the potassium carbonate is 60 - 90 wt%, preferably 80 - 90 wt%. The mass concentration of the potassium hydroxide is 60 - 90 wt%, preferably 80 - 90 wt%.

[0027] Preferably, the impregnation time in S2 is 1 to 3 h.

[0028] Preferably, the heating rate of high-temperature activation in S3 is 1 to 15 °C / min.

[0029] The present invention also discloses a distiller's grains activated carbon prepared by the preparation method of the distiller's grains activated carbon described above.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] The present invention uses the main waste by-products in the brewing industry as raw materials to prepare activated carbon. Using brewing wastewater for hydrothermal carbonization can not only improve the yield of activated carbon, but also enhance the adsorption performance of activated carbon. The brewing wastewater contains more alcohols, acids, and esters, which have a high solubility in the condensation of biomass hydrothermal reactions to produce small-molecule compounds. By repeated use, the organic matter content in the wastewater can be increased. The final organic wastewater can be used to extract by-products such as acetic acid, lactic acid, or biomass heavy oil through vacuum distillation or used as fuel for a biomass thermal power plant. The activated carbon of the present invention has low production cost, low energy consumption, environmental friendliness, and high resource utilization rate, and has good industrial application prospects. Specific embodiments

[0032] The following describes specific embodiments of the present invention. The described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0033] Example 1

[0034] A preparation method for improving the performance of distiller's grains activated carbon, and the specific technical solution includes:

[0035] (1) Take 5 g of distiller's grains powder dried at 105 °C and pulverized to 200 meshes, add 50 mL of yellow water, mix well, transfer it into a reaction kettle, and carry out hydrothermal carbonization at 180 °C for 12 h. The obtained carbonized product is filtered, washed, and dried.

[0036] (2) Take 1 g of the dried hydrothermal carbon, add 6.25 g of a phosphoric acid aqueous solution with a mass concentration of 40 wt%, impregnate for 2 h, and then dry at 105 °C.

[0037] (3) Place the impregnated and dried hydrothermal carbon in a tubular furnace, under nitrogen protection, heat it to 650 °C at a rate of 5 °C / min for activation for 60 min, and then cool it naturally, wash it, and dry it to obtain phosphoric acid-activated distiller's grains-based activated carbon.

[0038] The mass yield of the prepared distiller's grains activated carbon is 29.53%, and the methylene blue adsorption capacity reaches 382.77 mg / g.

[0039] Comparative example 1

[0040] The difference between Comparative Example 1 and Example 1 is that the hydrothermal carbonization in step (1) of Example 1 was changed to high-temperature carbonization using a tube furnace. The carbonization conditions were heating to 450 °C at a rate of 5 °C / min under nitrogen protection, carbonizing for 60 min, and then naturally cooling.

[0041] The mass yield of the finally prepared distillers' grains activated carbon was 16.72%, and the methylene blue adsorption capacity was 252.15 mg / g. Compared with the activated carbon yield and its saturated methylene blue adsorption capacity in Example 1, the activated carbon yield prepared in Example 1 increased by 12.81% compared with Comparative Example 1, and the saturated methylene blue adsorption capacity increased by 130.62 mg / g compared with Comparative Example 1. This shows that hydrothermal carbonization can reduce the loss of carbon source caused by the high-temperature condensation of distillers' grains cellulose or lignin, retain some N and O heteroatoms to increase the surface active groups, thereby improving the yield and adsorption performance of the activated carbon.

[0042] Comparative Example 2

[0043] The difference between Comparative Example 2 and Example 1 is that distillers' grains were not added in step (1) of Example 1, and only 50 mL of yellow water was hydrothermally carbonized, and then activated carbon from yellow water was prepared according to the same process.

[0044] The finally prepared activated carbon yield was approximately 0.0117 g / 50 mL of yellow water, and the saturated methylene blue adsorption capacity was 194.26 mg / g. Compared with the activated carbon yield and its saturated methylene blue adsorption capacity in Example 1, the activated carbon formed by the hydrothermal carbonization of yellow water alone in Comparative Example 2 accounted for approximately 0.79% of the yield of the distillers' grains hydrothermal activated carbon in Example 1, and the methylene blue adsorption capacity was 188.51 mg / g lower than that of the activated carbon in Example 1. This shows that the activated carbon prepared by directly hydrothermally carbonizing yellow water has a high degree of carbonization and few surface active groups, resulting in poor adsorption effect of the activated carbon.

[0045] Comparative Example 3

[0046] The difference between Comparative Example 3 and Example 1 is that the hydrothermal reaction medium yellow water used in step (1) of Example 1 was changed to 50 mL of deionized water.

[0047] The mass yield of the prepared distillers' grains activated carbon is 25.65%, and the methylene blue adsorption capacity is 358.61 mg / g. Compared with the activated carbon yield in Example 1 and its saturated methylene blue adsorption capacity, the activated carbon yield prepared in Example 1 is 3.88% higher than that in Comparative Example 3, and the saturated methylene blue adsorption capacity is 24.16 mg / g higher than that in Comparative Example 3. It may be because lactic acid, amino acids, glucose, soluble starch, etc. contained in the yellow water can penetrate into the interior of the fibers of the distillers' grains and carbonize together with the distillers' grains, increasing the active groups on the surface of the activated carbon, thereby improving the yield and adsorption performance of the activated carbon. The activated carbon yield prepared in Example 1 is 3.88% higher than that in Comparative Example 3. From Comparative Example 2, it can be seen that the activated carbon formed by hydrothermal carbonization of the yellow water alone in Comparative Example 2 accounts for about 0.79% of the yield of the distillers' grains hydrothermal activated carbon in Example 1, that is, the activated carbon directly formed by carbonizing the yellow water only accounts for 0.79% of the activated carbon formed in Example 1. That is, the yield of 29.53% of the hydrothermal carbonization of yellow water and distillers' grains in Example 1 is higher than the sum of the yields of Comparative Example 2 (0.79%) and Comparative Example 3 (25.65%). The interaction of yellow water and distillers' grains in hydrothermal carbonization can synergistically increase the yield of activated carbon.

[0048] Comparative Example 4

[0049] The difference between Comparative Example 4 and Example 1 is that the hydrothermal reaction temperature in step (1) of Example 1 is adjusted to 220 °C.

[0050] The mass yield of the prepared distillers' grains activated carbon is 27.34%, and the methylene blue adsorption capacity is 343.85 mg / g. Compared with the activated carbon yield in Example 1 and its saturated methylene blue adsorption capacity, the activated carbon yield prepared in Example 1 is 2.19% higher than that in Comparative Example 4, and the saturated methylene blue adsorption capacity is 38.92 mg / g higher than that in Comparative Example 4. It may be because the degree of hydrothermal condensation increases after the hydrothermal temperature rises in Comparative Example 4, resulting in a decrease in the activated carbon yield and adsorption performance.

[0051] Comparative Example 5

[0052] The difference between Comparative Example 5 and Example 1 is that the dosage of 40 wt% phosphoric acid aqueous solution in step (2) of Example 1 is adjusted to 3.75 g, where the mass of the activator phosphoric acid is 3.75 g × 40 wt% = 1.5 g, and the mass ratio of the activator phosphoric acid to the hydrothermal carbon is 1.5.

[0053] The mass yield of the prepared distillers' grains activated carbon is 32.77%, and the methylene blue adsorption capacity is 263.35 mg / g. Compared with the activated carbon yield in Example 1 and its saturated methylene blue adsorption capacity, the activated carbon yield prepared in Example 1 is 1.24% lower than that in Comparative Example 5, and the saturated methylene blue adsorption capacity is 119.42 mg / g higher than that in Comparative Example 4. This is mainly because the lower dosage of the activator cannot form more pore structures.

[0054] Comparative Example 6

[0055] The difference between Comparative Example 6 and Example 1 is that the amount of 40 wt% phosphoric acid aqueous solution in step (2) of Example 1 was adjusted to 8.75 g, where the mass of the activator phosphoric acid was 8.75 g * 40 wt% = 3.5 g, and the mass ratio of the activator phosphoric acid to hydrothermal carbon was 3.5.

[0056] The mass yield of the prepared distiller's grains activated carbon was 22.46%, and the methylene blue adsorption capacity was 344.96 mg / g. Compared with the activated carbon yield of Example 1 and its saturated methylene blue adsorption capacity, the activated carbon yield prepared in Example 1 increased by 1.07% compared to Comparative Example 6, and the saturated methylene blue adsorption capacity increased by 37.81 mg / g compared to Comparative Example 6. This was mainly because the increase in the amount of the activator led to the collapse of the porous structure of the activated carbon, and more macropores were formed inside the activated carbon, resulting in a decrease in the specific surface area of the activated carbon and a decrease in the adsorption capacity.

[0057] Comparative Example 7

[0058] The difference between Comparative Example 7 and Example 1 is that the activation temperature in step (3) of Example 1 was adjusted to 550 °C.

[0059] The mass yield of the prepared distiller's grains activated carbon was 32.62%, and the methylene blue adsorption capacity was 342.00 mg / g. Compared with the activated carbon yield of Example 1 and its saturated methylene blue adsorption capacity, the activated carbon yield prepared in Example 1 decreased by 3.09% compared to Comparative Example 7, and the saturated methylene blue adsorption capacity increased by 40.77 mg / g compared to Comparative Example 7. This may be because the activation temperature was relatively low, and some of the uncondensed molecules remaining in the activated carbon precursor could not undergo condensation reactions to form a porous structure, resulting in a decrease in the specific surface area of the activated carbon and a decrease in the adsorption capacity.

[0060] Comparative Example 8

[0061] The difference between Comparative Example 8 and Example 1 is that the activation temperature in step (3) of Example 1 was adjusted to 750 °C.

[0062] The mass yield of the prepared distiller's grains activated carbon was 27.54%, and the methylene blue adsorption capacity was 256.98 mg / g. Compared with the activated carbon yield of Example 1 and its saturated methylene blue adsorption capacity, the activated carbon yield prepared in Example 1 increased by 1.99% compared to Comparative Example 8, and the saturated methylene blue adsorption capacity increased by 125.79 mg / g compared to Comparative Example 8. This may be because the activation temperature was too high, resulting in the collapse of the microporous structure of the activated carbon and a decrease in the specific surface area, causing a decrease in the adsorption capacity.

[0063] Example 2

[0064] A preparation method for improving the performance of distillers' grains activated carbon, and the specific technical solution includes:

[0065] (1) Take 5 g of distillers' grains powder dried at 105 °C and crushed to 200 mesh, add 50 mL of yellow water that has been subjected to repeated hydrothermal reactions 4 times, mix well and transfer it into a reaction kettle, carry out hydrothermal carbonization at 180 °C for 12 h, and filter, wash and dry the obtained carbonized product;

[0066] (2) Take 1 g of the dried hydrothermally carbonized material, add 6.25 g of phosphoric acid aqueous solution with a mass concentration of 40 wt%, impregnate for 2 h and then dry at 105 °C;

[0067] (3) Place the impregnated and dried hydrothermally carbonized material in a tubular furnace, under nitrogen protection, heat it up to 650 °C at a rate of 5 °C / min and activate for 60 min, naturally cool and then wash and dry to obtain phosphoric acid-activated distillers' grains-based activated carbon.

[0068] The mass yield of the prepared distillers' grains activated carbon is 30.35%, and the methylene blue adsorption capacity is 367.05 mg / g.

[0069] As can be seen from Example 2, adding the yellow water subjected to repeated hydrothermal reactions can further improve the mass yield of distillers' grains activated carbon.

[0070] Comparative Example 9

[0071] The difference between Comparative Example 9 and Example 2 is that the yellow water, the hydrothermal reaction medium reused in step (1) of Example 2, is changed to 50 mL of hydrothermal wastewater reused 4 times.

[0072] The mass yield of the prepared distillers' grains activated carbon is 25.37%, and the methylene blue adsorption capacity is 275.66 mg / g. Compared with the activated carbon yield in Example 2 and its saturated methylene blue adsorption capacity, the activated carbon yield prepared in Example 2 is 4.98% higher than that in Comparative Example 9, and the saturated methylene blue adsorption capacity is 91.39 mg / g higher than that in Comparative Example 9. It shows that the yellow water in Example 2 has little influence on the adsorption performance of activated carbon after being reused as a hydrothermal reaction medium. Therefore, the organic matter concentration can be increased by reusing the hydrothermal wastewater of yellow water, which is convenient for post-treatment to prepare acetic acid, lactic acid or bio-oil products.

[0073] Example 3

[0074] A preparation method for improving the performance of distillers' grains activated carbon, and the specific technical solution includes:

[0075] (1) Take 5 g of distillers' grains powder dried at 105 °C and crushed to 200 mesh, add 50 mL of yellow water, mix well and transfer it into a reaction kettle, carry out hydrothermal carbonization at 180 °C for 12 h, and filter, wash and dry the obtained carbonized product;

[0076] (2) Take 1 g of the hydrothermal carbon after drying, add 9 g of an aqueous potassium carbonate solution with a mass concentration of 80 wt%, impregnate for 2 h, and then dry at 105 °C;

[0077] (3) Place the impregnated and dried hydrothermal carbon in a tubular furnace, under nitrogen protection, heat it to 750 °C at a rate of 5 °C / min for activation for 60 min, naturally cool it, wash and dry it to obtain potassium carbonate-activated distiller's grains-based activated carbon.

[0078] The mass yield of the prepared distiller's grains activated carbon is 24.02%, and the methylene blue adsorption capacity reaches 754.48 mg / g.

[0079] Comparative Example 10

[0080] The difference between Comparative Example 10 and Example 3 is that the hydrothermal carbonization in step (1) of Example 3 is changed to high-temperature carbonization using a tubular furnace. The carbonization conditions are to heat it to 450 °C at a rate of 5 °C / min for carbonization for 60 min under nitrogen protection and then naturally cool it.

[0081] Finally, the mass yield of the prepared distiller's grains activated carbon is 12.63%, and the methylene blue adsorption capacity is 537.33 mg / g. Compared with the activated carbon yield of Example 3 and its saturated methylene blue adsorption capacity, the activated carbon yield prepared in Example 3 increases by 11.39% compared with Comparative Example 10, and the saturated methylene blue adsorption capacity increases by 217.15 mg / g compared with Comparative Example 10. It shows that the carbon skeleton retained after hydrothermal carbonization has higher high-temperature stability, so the activated carbon yield increases significantly after high-temperature activation.

[0082] Comparative Example 11

[0083] The difference between Comparative Example 11 and Example 3 is that the yellow water used as the hydrothermal reaction medium in step (1) of Example 3 is changed to 50 mL of deionized water.

[0084] The mass yield of the prepared distiller's grains activated carbon is 22.74%, and the methylene blue adsorption capacity is 633.54 mg / g. Compared with the activated carbon yield of Example 3 and its saturated methylene blue adsorption capacity, the activated carbon yield prepared in Example 3 increases by 1.28% compared with Comparative Example 11, and the saturated methylene blue adsorption capacity increases by 120.94 mg / g compared with Comparative Example 11. It shows that using yellow water as the hydrothermal medium can increase the yield and adsorption performance of activated carbon compared with deionized water.

[0085] Example 4

[0086] A preparation method for improving the performance of distiller's grains activated carbon, and the specific technical solution includes:

[0087] (1) Take 5 g of distiller's grains powder that has been dried at 105 °C and crushed to 200 mesh, add 50 mL of yellow water, mix well, transfer it into a reaction kettle, and perform hydrothermal carbonization at 180 °C for 12 h. Filter, wash, and dry the obtained carbonized product.

[0088] (2) Take 1 g of the dried hydrothermal carbon, add 3.75 g of an aqueous potassium hydroxide solution with a mass concentration of 80 wt%, impregnate for 2 h, and then dry at 105 °C.

[0089] (3) Place the impregnated and dried hydrothermal carbon in a tubular furnace. Under nitrogen protection, heat it to 750 °C at a rate of 5 °C / min and activate for 60 min. After natural cooling, wash and dry to obtain potassium hydroxide-activated distiller's grains-based activated carbon.

[0090] The mass yield of the prepared distiller's grains activated carbon is 18.26%, and the methylene blue adsorption capacity reaches 1267.80 mg / g.

[0091] Comparative Example 12

[0092] The difference between Comparative Example 12 and Example 4 is that the hydrothermal carbonization in step (1) of Example 4 is changed to high-temperature carbonization using a tubular furnace. The carbonization conditions are heating to 450 °C at a rate of 5 °C / min under nitrogen protection and carbonizing for 60 min, followed by natural cooling.

[0093] Finally, the mass yield of the prepared distiller's grains activated carbon is 10.47%, and the methylene blue adsorption capacity is 968.49 mg / g. Compared with the activated carbon yield and its saturated methylene blue adsorption capacity in Example 4, the activated carbon yield prepared in Example 4 is increased by 7.79% compared to Comparative Example 12, and the saturated methylene blue adsorption capacity is increased by 299.31 mg / g compared to Comparative Example 12. This shows that the carbon skeleton retained after hydrothermal carbonization has higher high-temperature stability, so the activated carbon yield increases significantly after high-temperature activation.

[0094] Comparative Example 13

[0095] The difference between Comparative Example 13 and Example 4 is that the yellow water used as the hydrothermal reaction medium in step (1) of Example 4 is changed to 50 mL of deionized water.

[0096] The mass yield of the prepared distiller's grains activated carbon is 16.36%, and the methylene blue adsorption capacity is 1083.41 mg / g. Compared with the activated carbon yield and its saturated methylene blue adsorption capacity in Example 4, the activated carbon yield prepared in Example 4 is increased by 1.90% compared to Comparative Example 13, and the saturated methylene blue adsorption capacity is increased by 184.39 mg / g compared to Comparative Example 13. This shows that using yellow water as the hydrothermal medium can increase the yield and adsorption performance of activated carbon compared to using deionized water as the hydrothermal medium.

[0097] Table 1 Process parameters, yields, and adsorption capacities of Examples 1 - 4 and Comparative Examples 1 - 13

[0098]

[0099]

[0100] As described above, it is only the preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and concept of the present invention, makes substitutions and improvements to achieve the same operation effect, and should be covered within the protection scope of the present invention.

Claims

1. A preparation method of distiller's grains activated carbon, characterized in that It includes the following steps: S1. Dry and crush distiller's grains, add brewing wastewater and mix for hydrothermal carbonization, filter, wash, and dry to obtain hydrothermal carbon; S2. Add an activator to the hydrothermal carbon obtained in S1, impregnate, and dry to obtain the impregnated hydrothermal carbon; S3. Subject the impregnated hydrothermal carbon obtained in S2 to high-temperature activation under inert gas protection or in a vacuum environment, cool, wash, and dry to obtain the product.

2. The preparation method of distiller's grains activated carbon according to claim 1, characterized in that, The brewing wastewater described in S1 is one or a mixture of the bottom pot water or yellow water during the brewing process; preferably yellow water.

3. The preparation method of the distiller's grains activated carbon according to claim 1, wherein, The filtrate obtained by filtration in S1 can be mixed with the dried and crushed distiller's grains again for hydrothermal carbonization and can be reused 1 to 5 times.

4. The preparation method of distiller's grains activated carbon according to claim 1, wherein, The temperature of the hydrothermal carbonization in S1 is 160 - 200 °C, and the time is 6 - 48 h.

5. The preparation method of distiller's grains activated carbon according to any one of claims 1-4, characterized in that, The activator described in S2 is one or more of phosphoric acid, potassium dihydrogen phosphate, potassium carbonate, and potassium hydroxide.

6. The preparation method of the distiller's grains activated carbon according to claim 5, characterized in that, When the activator is phosphoric acid or potassium dihydrogen phosphate, the mass ratio of the activator to the hydrothermal carbon is 2.0 - 4.0; preferably, the mass ratio of the activator to the hydrothermal carbon is 2.0 - 3.

0.

7. The preparation method of distiller's grains activated carbon according to claim 5, characterized in that, When the activator is potassium carbonate or potassium hydroxide, the mass ratio of the activator to the hydrothermal carbon is 3.0 - 5.0; preferably, the mass ratio of the activator to the hydrothermal carbon is 3.0 - 4.

0.

8. The preparation method of distiller's grains activated carbon according to claim 1, characterized in that, The volume-weight ratio of the brewing wastewater to the dried distiller's grains in S1 is 5 - 20 mL / g; preferably 5 - 15 mL / g.

9. The preparation method of distiller's grains activated carbon according to any one of claims 1-4, characterized in that, The temperature of the high-temperature activation in S3 is 600 - 800 °C, and the activation time is 30 - 90 min; preferably, when the activator is phosphoric acid or potassium dihydrogen phosphate, the activation temperature is 600 - 700 °C; when the activator is potassium carbonate or potassium hydroxide, the activation temperature is 700 - 800 °C.

10. A distiller's grains activated carbon prepared by the method for preparing distiller's grains activated carbon according to any one of claims 1 - 9.

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