A high-strength sugar residue-based activated carbon for water purification and its preparation method

Abstract

The present invention relates to a high-strength sugar residue-based activated carbon for water purification and a preparation method thereof, belonging to the technical field of activated carbon preparation. The high-strength sugar residue-based activated carbon for water purification comprises the following components: a substrate, a flocculant, and a binder; the substrate is bagasse; the flocculant comprises inorganic silica gel powder, polyaluminum chloride, and polyacrylamide; and the binder comprises sodium carboxymethyl cellulose, waste molasses, and inorganic silicate. The present invention uses sodium carboxymethyl cellulose, waste molasses, and inorganic silicate mixed in proportion as a binder, and carbonizes them at 300-350°C. This improves the strength of the activated carbon while also improving the specific surface area and adsorption capacity of the activated carbon. At the same time, it overcomes the problem of sodium carboxymethyl cellulose penetrating into the pores of the activated carbon during the extrusion molding process after increasing the amount of sodium carboxymethyl cellulose added, causing pore blockage.

Description

Technical Field

[0001] The invention belongs to the technical field of activated carbon preparation, and relates to a high-strength sugar residue-based activated carbon specially used for water purification and a preparation method thereof. Background Art

[0002] Activated carbon refers to a specially treated carbon. Organic raw materials are heated in an airtight environment to carbonize them to reduce non-carbon components. Then, they are activated by reacting with gas or liquid reagents. The surface is eroded, and a structure with well-developed micropores is produced. Since the activation process is a microscopic process, that is, the surface erosion of a large number of molecular carbides is point-like erosion, resulting in countless tiny pores on the surface of activated carbon. The diameter of the micropores on the surface of activated carbon is mostly between 2 and 50 nm. Even a small amount of activated carbon has a huge surface area. The surface area of ​​each gram of activated carbon is 500 to 1500 m 2 Almost all applications of activated carbon are based on this characteristic of activated carbon.

[0003] Activated carbon is primarily used as a solid adsorbent in the chemical, pharmaceutical, and environmental sectors, adsorbing substances with high boiling points and critical temperatures, as well as organic compounds with large molecular weights. Its application in fields such as air purification and water treatment is also showing a growing trend. Specialized high-grade carbons, such as high-surface-area carbon, high-benzene carbon, and fiber carbon, have penetrated into aerospace, electronics, communications, energy, bioengineering, and life sciences.

[0004] The activated carbon preparation process includes grinding into fine powder, binding to form columns, carbonization, activation, cooling, rinsing, drying, and packaging. The key to producing high-strength activated carbon lies in the binder used. Currently, mainstream binders include polyvinyl alcohol, sodium carboxymethyl cellulose, and humic acid. Using sodium carboxymethyl cellulose can produce activated carbon with very high strength properties, but increasing the amount of sodium carboxymethyl cellulose added tends to cover the activated carbon pores, resulting in a decrease in specific surface area and a decrease in adsorption capacity. Existing research shows that when the sodium carboxymethyl cellulose addition is 10%, the activated carbon strength is 97.98%, with the best adsorption capacity; when the sodium carboxymethyl cellulose addition is 20%, the activated carbon strength can reach 99.97%. However, due to the increased amount of sodium carboxymethyl cellulose added, the binder penetrates into the pores of the activated carbon during the extrusion process, causing pore blockage, a decrease in specific surface area, and a decrease in adsorption capacity.

[0005] Patent CN116393094A discloses an activated carbon with high water purification efficiency and its preparation process, relating to the field of activated carbon technology. The activated carbon with high water purification efficiency comprises the following components by weight: 50-70 parts of coal powder, 10-12 parts of an organic binder, 7-9 parts of cassava flour, 10-15 parts of silica gel, 1-5 parts of a flocculant, 1-9 parts of a conditioning agent, and 1-6 parts of yellow dextrin. In the present invention, the added silica gel can adsorb organic matter and heavy metal ions in the water, thereby improving the water purification effect. The flocculant can help suspended particles in the water to quickly agglomerate into large particles, facilitating subsequent filtration and separation, thereby ensuring the water purification effect. The conditioning agent can make the water quality closer to alkaline, ensuring that the water body is in an appropriate acid-base balance range, thereby further ensuring the water purification effect. The invention has high practicality and significant progress.

[0006] Patent CN116272926A discloses a method for preparing activated carbon for decolorizing dye wastewater, a product thereof, and a method for decolorizing dye wastewater, aiming to improve the decolorization effect of activated carbon dyes. The method comprises: taking bamboo as raw material, cutting, drying, crushing, and sieving to obtain a crushed material, then carbonizing the crushed material to obtain a carbonized material; performing a primary activation on the carbonized material to obtain a primary activated material; performing a secondary activation on the primary activated material to obtain a secondary activated material; washing the secondary activated material, and immersing the washed secondary activated material in a chitosan organic solution, stirring at 25°C-60°C for 1-6 hours, and then drying to obtain an activated carbon product; assuming that the volume of the chitosan organic solution is M ml, the chitosan content in the chitosan organic solution is 0.1M g / L to 0.4M g / L, and the amount of the secondary activated material added is 0.5M g.

[0007] Patent CN116199224A discloses a method for preparing coal-based granular activated carbon, a product, and a method for decolorizing dye wastewater to address the technical problem of improving the decolorization effect of granular activated carbon. The method comprises: taking coal as a raw material, crushing it to obtain a crushed material, then demineralizing the crushed material to obtain a demineralized material, wherein the demineralization treatment comprises mixing the crushed material with a demineralizing solution containing hydrochloric acid and / or hydrofluoric acid; forming the demineralized material into granules and activating it to obtain a crude activated carbon product, which is then washed to obtain a washed crude activated carbon product; immersing the washed crude activated carbon product in a carbon quantum dot solution, calcining it, and then washing it to obtain a coal-based granular activated carbon product, wherein the oxygen-containing functional groups on the carbon core surface of the carbon quantum dot solution are mainly hydroxyl functional groups and amide functional groups. Summary of the Invention

[0008] The purpose of the present invention is to provide a high-strength sugar residue-based activated carbon for water purification and a preparation method thereof. The high-strength sugar residue-based activated carbon for water purification has the characteristics of high strength, large specific surface area and good adsorption performance.

[0009] The purpose of the present invention can be achieved through the following technical solutions:

[0010] A method for preparing high-strength sugar residue-based activated carbon for water purification comprises the following steps:

[0011] (1) Grinding bagasse into powder using a grinding device as a base material powder;

[0012] (2) grinding the inorganic silica gel in a grinding device to obtain inorganic silica gel powder;

[0013] (3) uniformly mixing the inorganic silica gel powder ground in step (2) with polyaluminium chloride and polyacrylamide in proportion to form a flocculant;

[0014] (4) mixing sodium carboxymethyl cellulose, waste molasses, and inorganic silicate in proportion to form a binder;

[0015] (5) adding the substrate powder, flocculant, and binder into a blender in proportion and stirring evenly, then placing the mixture in a cylindrical mold and press-molding to obtain a columnar activated carbon precursor;

[0016] (6) subjecting the columnar activated carbon precursor prepared in step (5) to carbonization and activation treatments in sequence;

[0017] (7) rinsing and drying the activated product in step (6) to obtain high-strength sugar residue-based activated carbon for water purification.

[0018] As a preferred technical solution of the present invention, the particle size of the base material powder in step (1) and the inorganic silica gel powder in step (2) are both 100 mesh.

[0019] As a preferred technical solution of the present invention, the proportion mentioned in step (3) refers to the weight ratio of inorganic silica gel powder, polyaluminum chloride and polyacrylamide being 2-4:1-3:1-3.

[0020] As a preferred technical solution of the present invention, the proportion mentioned in step (4) refers to the weight ratio of sodium carboxymethyl cellulose, waste molasses and inorganic silicate being 10-25:3-10:2-5.

[0021] As a preferred technical solution of the present invention, the inorganic silicate described in step (4) is sodium silicate.

[0022] As a preferred technical solution of the present invention, the proportion mentioned in step (5) refers to the weight ratio of the base material powder, flocculant and binder being 55-84:1-5:15-40.

[0023] As a preferred technical solution of the present invention, the carbonization time in step (6) is 1 to 2 hours.

[0024] As a preferred technical solution of the present invention, the carbonization temperature in step (6) is 300-350°C.

[0025] As a preferred technical solution of the present invention, the activation described in step (6) refers to activation using any one of ZnCl2, KOH, NaOH, and K2CO3 as an activating agent.

[0026] Beneficial effects of the present invention:

[0027] (1) The present invention uses sodium carboxymethyl cellulose, waste molasses and inorganic silicate mixed in proportion as a binder. The waste molasses in the binder loses water, hydrogen, oxygen molecules and light hydrocarbons after carbonization, leaving pores, which not only improves the strength of the activated carbon but also improves the specific surface area and adsorption capacity of the activated carbon.

[0028] (2) The present invention uses sodium carboxymethyl cellulose, waste molasses and inorganic silicate mixed in proportion as a binder, which reduces the permeability of sodium carboxymethyl cellulose during the activated carbon pressurization molding process. A small amount of binder that penetrates into the pores is left behind because the waste molasses in the binder loses water, hydrogen, oxygen molecules and light hydrocarbons after carbonization, thereby overcoming the problem of reduced specific surface area caused by sodium carboxymethyl cellulose penetrating into the pores of the activated carbon during the extrusion molding process after increasing the amount of sodium carboxymethyl cellulose added. While improving the strength, it also avoids pore clogging.

[0029] (3) The present invention uses bagasse as raw material, sodium carboxymethyl cellulose, waste molasses and inorganic silicate as binders, and carbonization can be completed at a temperature of 300-350° C., which can effectively reduce energy consumption.

[0030] (4) The present invention uses waste bagasse and waste molasses generated during the industrial production of sucrose as main raw materials, thereby reducing the pollution to the environment caused by burning or abandoning the bagasse and waste molasses. DETAILED DESCRIPTION

[0031] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with the embodiments.

[0032] Example 1

[0033] A method for preparing high-strength sugar residue-based activated carbon for water purification comprises the following steps:

[0034] (1) Grinding bagasse into 100 mesh in a grinding device to obtain base material powder;

[0035] (2) grinding the inorganic silica gel to 100 mesh in a grinding device to obtain inorganic silica gel powder;

[0036] (3) mixing the inorganic silica gel powder ground in step (2) with polyaluminium chloride and polyacrylamide in a weight ratio of 2:1:2 to form a flocculant;

[0037] (4) mixing sodium carboxymethyl cellulose, molasses, and sodium silicate in a weight ratio of 10:3:2 to form a binder;

[0038] (5) adding the substrate powder, flocculant, and binder in a weight ratio of 55:5:40 into a blender and stirring evenly, then placing the mixture in a cylindrical mold and press-molding to obtain a columnar activated carbon precursor;

[0039] (6) carbonizing the columnar activated carbon precursor in step (5) and activating it with KOH as an activating agent;

[0040] (7) rinsing and drying the activated product in step (6) to obtain high-strength sugar residue-based activated carbon for water purification.

[0041] In this embodiment, the carbonization temperature is 340° C. and the carbonization time is 1.2 h.

[0042] The BET specific surface area, methylene blue adsorption value, iodine adsorption value and strength of the high-strength activated carbon for water purification prepared in this embodiment were measured. The BET specific surface area was calculated using the BET equation, and the methylene blue adsorption value, iodine adsorption value and strength were measured in accordance with the national standards of the People's Republic of China GB / T12496.10-1999, GB / T12496.8-1999 and GB / T12496.6-1999.

[0043] Example 2

[0044] A method for preparing high-strength sugar residue-based activated carbon for water purification comprises the following steps:

[0045] (1) Grinding bagasse into 100 mesh in a grinding device to obtain base material powder;

[0046] (2) grinding the inorganic silica gel to 100 mesh in a grinding device to obtain inorganic silica gel powder;

[0047] (3) mixing the inorganic silica gel powder ground in step (2) with polyaluminium chloride and polyacrylamide in a weight ratio of 3:1:2 to form a flocculant;

[0048] (4) mixing sodium carboxymethyl cellulose, molasses, and sodium silicate in a weight ratio of 12:5:3 to form a binder;

[0049] (5) adding the substrate powder, flocculant, and binder in a weight ratio of 65:5:30 into a blender and stirring evenly, then placing the mixture in a cylindrical mold and press-molding to obtain a columnar activated carbon precursor;

[0050] (6) carbonizing the columnar activated carbon precursor in step (5) and activating it with NaOH as an activating agent;

[0051] (7) rinsing and drying the activated product in step (6) to obtain high-strength sugar residue-based activated carbon for water purification.

[0052] In this embodiment, the carbonization temperature is 350° C. and the carbonization time is 1 h.

[0053] The BET specific surface area, methylene blue adsorption value, iodine adsorption value and strength of the high-strength activated carbon for water purification prepared in this embodiment were measured. The BET specific surface area was calculated using the BET equation, and the methylene blue adsorption value, iodine adsorption value and strength were measured in accordance with the national standards of the People's Republic of China GB / T12496.10-1999, GB / T12496.8-1999 and GB / T12496.6-1999.

[0054] Example 3

[0055] A method for preparing high-strength sugar residue-based activated carbon for water purification comprises the following steps:

[0056] (1) Grinding bagasse into 100 mesh in a grinding device to obtain base material powder;

[0057] (2) grinding the inorganic silica gel to 100 mesh in a grinding device to obtain inorganic silica gel powder;

[0058] (3) mixing the inorganic silica gel powder ground in step (2) with polyaluminium chloride and polyacrylamide in a weight ratio of 4:2:3 to form a flocculant;

[0059] (4) mixing sodium carboxymethyl cellulose, molasses, and sodium silicate in a weight ratio of 18:8:4 to form a binder;

[0060] (5) adding the substrate powder, flocculant, and binder in a weight ratio of 70:5:25 into a blender and stirring evenly, then placing the mixture in a cylindrical mold and press-molding to obtain a columnar activated carbon precursor;

[0061] (6) carbonizing the columnar activated carbon precursor in step (5) and activating it with ZnCl2 as an activating agent;

[0062] (7) rinsing and drying the activated product in step (6) to obtain high-strength sugar residue-based activated carbon for water purification.

[0063] In this embodiment, the carbonization temperature is 300° C. and the carbonization time is 2 h.

[0064] The BET specific surface area, methylene blue adsorption value, iodine adsorption value and strength of the high-strength activated carbon for water purification prepared in this embodiment were measured. The BET specific surface area was calculated using the BET equation, and the methylene blue adsorption value, iodine adsorption value and strength were measured in accordance with the national standards of the People's Republic of China GB / T12496.10-1999, GB / T12496.8-1999 and GB / T12496.6-1999.

[0065] Example 4

[0066] A method for preparing high-strength sugar residue-based activated carbon for water purification comprises the following steps:

[0067] (1) Grinding bagasse into 100 mesh in a grinding device to obtain base material powder;

[0068] (2) grinding the inorganic silica gel to 100 mesh in a grinding device to obtain inorganic silica gel powder;

[0069] (3) mixing the inorganic silica gel powder ground in step (2) with polyaluminium chloride and polyacrylamide in a weight ratio of 3:2:3 to form a flocculant;

[0070] (4) mixing sodium carboxymethyl cellulose, molasses, and sodium silicate in a weight ratio of 20:7:3 to form a binder;

[0071] (5) adding the substrate powder, flocculant, and binder in a weight ratio of 65:5:30 into a blender and stirring evenly, then placing the mixture in a cylindrical mold and press-molding to obtain a columnar activated carbon precursor;

[0072] (6) carbonizing the columnar activated carbon precursor in step (5) and activating it with K2CO3 as an activating agent;

[0073] (7) rinsing and drying the activated product in step (6) to obtain high-strength sugar residue-based activated carbon for water purification.

[0074] In this embodiment, the carbonization temperature is 310° C. and the carbonization time is 1.8 h.

[0075] The BET specific surface area, methylene blue adsorption value, iodine adsorption value and strength of the high-strength activated carbon for water purification prepared in this embodiment were measured. The BET specific surface area was calculated using the BET equation, and the methylene blue adsorption value, iodine adsorption value and strength were measured in accordance with the national standards of the People's Republic of China GB / T12496.10-1999, GB / T12496.8-1999 and GB / T12496.6-1999.

[0076] Comparative Example 1

[0077] No waste molasses was added, and the weight ratio of sodium carboxymethyl cellulose and inorganic silicate was 26:4. The rest of the configuration and operation method were the same as in Example 3.

[0078] Comparative Example 2

[0079] No waste molasses was added, and the weight ratio of sodium carboxymethyl cellulose and inorganic silicate was 18:12. The rest of the configuration and operation method were the same as in Example 3.

[0080] Comparative Example 3

[0081] No inorganic silicate was added, and the weight ratio of sodium carboxymethyl cellulose and molasses was 26:4. The rest of the configuration and operation method were the same as in Example 3.

[0082] Comparative Example 4

[0083] No inorganic silicate was added, and the weight ratio of sodium carboxymethyl cellulose and waste molasses was 18:12. The rest of the configuration and operation method were the same as in Example 3.

[0084] Comparative Example 5

[0085] No sodium carboxymethyl cellulose was added, and the inorganic silicate and waste molasses were in a weight ratio of 26:4. The rest of the configuration and operation method were the same as in Example 3.

[0086] Comparative Example 6

[0087] No sodium carboxymethyl cellulose was added, and the inorganic silicate and waste molasses were in a weight ratio of 18:12. The rest of the configuration and operation method were the same as in Example 3.

[0088] Comparative Example 7

[0089] The carbonization temperature was adjusted to 260°C, and the remaining configurations and operating methods were the same as those in Example 3.

[0090] Comparative Example 8

[0091] The carbonization temperature was adjusted to 280°C, and the remaining configurations and operating methods were the same as those in Example 3.

[0092] Comparative Example 9

[0093] The carbonization temperature was adjusted to 370°C, and the remaining configurations and operating methods were the same as those in Example 3.

[0094] Comparative Example 10

[0095] The carbonization temperature was adjusted to 390° C., and the remaining configurations and operating methods were the same as those in Example 3.

[0096] The BET specific surface area, methylene blue adsorption value, iodine adsorption value, and strength measurement results of Examples 1-4 and Comparative Examples 1-10 are shown in Table 1 below. It can be clearly seen from the table that compared with Comparative Examples 1-10, Examples 1-4 using the unique binder formula provided by the present invention can better achieve the expected results. The reason for this may be that the use of sodium carboxymethyl cellulose, waste molasses, and sodium silicate as binders can improve the strength of the activated carbon while not significantly reducing the specific surface area. This effectively solves the problem that when the amount of sodium carboxymethyl cellulose added is increased, sodium carboxymethyl cellulose penetrates into the pores of the activated carbon during the extrusion molding process, causing pore blockage and a significant reduction in specific surface area. Comparative Examples 1-6 adjust the amount of sodium carboxymethyl cellulose, waste molasses, and inorganic silicate added to compare the differences in the BET specific surface area, methylene blue adsorption value, iodine adsorption value, and strength measurement results; Comparative Examples 7-10 adjust the carbonization temperature to compare the differences in the BET specific surface area, methylene blue adsorption value, iodine adsorption value, and strength measurement results. The BET specific surface area, methylene blue adsorption value, and iodine adsorption value results of Comparative Examples 1-2 and Comparative Examples 5-6 were all lower than those of Example 3, but the strengths were similar. The BET specific surface area, methylene blue adsorption value, and iodine adsorption value results of Comparative Examples 3-4 were similar to those of Example 3, but the strengths were lower. This may be because using only sodium carboxymethyl cellulose and inorganic silicate as binders, or sodium carboxymethyl cellulose and molasses as binders, does not achieve a good balance between specific surface area and strength. A comparison of the results of Example 3 with those of Comparative Examples 7-10 shows that when using the formulation of the present invention, the final activated carbon produced has the best performance when the carbonization temperature is 300-350°C.

[0097] Table 1 BET specific surface area, methylene blue adsorption value, iodine adsorption value and intensity measurement results

[0098]

[0099] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing high-strength sugar residue-based activated carbon for water purification, characterized in that: The following steps are involved: (1) Grinding bagasse into powder in a grinding device to use as base material powder; (2) Grinding the inorganic silica gel in a grinding device to obtain inorganic silica gel powder; (3) The inorganic silica gel powder ground in step (2) is mixed evenly with polyaluminium chloride and polyacrylamide in proportion to serve as a flocculant; (4) Mix sodium carboxymethyl cellulose, waste molasses, and inorganic silicate in proportion to form a binder; (5) Add the substrate powder, flocculant, and binder into a blender in proportion and mix them evenly, then place them in a cylindrical mold and press-form them to obtain a columnar activated carbon precursor; (6) sequentially carbonizing and activating the columnar activated carbon precursor in step (5); (7) rinsing and low-temperature drying the activated product in step (6) to obtain high-strength sugar residue-based activated carbon for water purification; The proportion mentioned in step (4) refers to the weight ratio of sodium carboxymethyl cellulose, waste molasses and inorganic silicate being 10~25:3~10:2~5.

2. The method for preparing a high-strength sugar residue-based activated carbon for water purification according to claim 1, characterized in that: The particle size of the substrate powder in step (1) and the inorganic silica gel powder in step (2) are both 100 mesh.

3. The method for preparing a high-strength sugar residue-based activated carbon for water purification according to claim 1, characterized in that: The proportion mentioned in step (3) refers to the weight ratio of inorganic silica gel powder, polyaluminium chloride and polyacrylamide being 2~4:1~3:1~3.

4. The method for preparing a high-strength sugar residue-based activated carbon for water purification according to claim 1, characterized in that: The inorganic silicate described in step (4) is sodium silicate.

5. The method for preparing a high-strength sugar residue-based activated carbon for water purification according to claim 1, characterized in that: The proportion mentioned in step (5) refers to the weight ratio of the base material powder, the flocculant and the binder being 55~84:1~5:15~40.

6. The method for preparing a high-strength sugar residue-based activated carbon for water purification according to claim 1, characterized in that: The carbonization temperature in step (6) is 300-350°C.

7. The method for preparing a high-strength sugar residue-based activated carbon for water purification according to claim 1, characterized in that: The carbonization time in step (6) is 1 to 2 hours.

8. The method for preparing a high-strength sugar residue-based activated carbon for water purification according to claim 1, characterized in that: The activation described in step (6) refers to activation using any one of ZnCl2, KOH, NaOH, and K2CO3 as an activating agent.

9. A high-strength sugar residue-based activated carbon for water purification prepared by the preparation method according to any one of claims 1 to 8.

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