Sludge-based biochar adsorption material and preparation method and application thereof

Abstract

The present disclosure relates to a sludge-based biochar adsorption material and a preparation method and application thereof, the method comprising the following steps: (1) ultrasonic treatment is performed on municipal sludge to obtain pretreated sludge; (2) the pretreated sludge is mixed with a modifier, and then carbonization treatment is performed under an inert atmosphere to obtain carbonized sludge-based; (3) the carbonized sludge-based, a magnesium-rich ore and an acidic reagent are mixed to perform impregnation treatment; (4) an amination reagent is added to the reaction system after impregnation treatment to perform amination reaction. The adsorption material has a large specific surface area and pore volume, can be used for adsorbing SO2 and has a high sulfur capacity. The preparation method has clean preparation process, low energy consumption, and has dual benefits of economy and environmental protection; effectively increases the metal loading and the amination degree, and improves the SO2 adsorption capacity.

Description

Technical Field

[0001] This disclosure relates to the technical field of material preparation and air pollution control, specifically to a sludge-based biochar adsorbent material, its preparation method, and its application. Background Technology

[0002] The sulfur oxides emitted by thermal power plants are mainly SO2, with a small portion converted into SO3. These gases, when released into the air, form acid rain, causing corrosion of buildings and soil acidification, and harming human health. In practical applications, SO2 removal is often achieved through adsorption and conversion. Adsorbents such as activated carbon, limestone, and silica are used for adsorption, while methods like ammonia, dual-alkali, organic solvent, and microbial methods convert SO2 into stable substances. Adsorption-based SO2 removal is a type of dry desulfurization technology that not only treats SO2 pollution in flue gas but also allows for the recovery and utilization of sulfur resources. Traditional adsorbents widely used in desulfurization include carbon-based materials, metal oxides, and molecular sieves. In recent years, various modified materials have been developed for these traditional adsorbents, such as alkali metal-modified carbon materials, metal oxide-modified carbon materials, alkali metal-modified molecular sieves, composite metal oxides, and supported metal oxides. Although these adsorbents have better SO2 adsorption effects than conventional adsorbents, they still have problems such as small sulfur capacity, limited SO2 removal efficiency, low strength of carbon materials, poor material stability, and high production costs. Summary of the Invention

[0003] The purpose of this disclosure is to provide a sludge-based biochar adsorbent material, its preparation method, and its application. The sludge-based biochar material prepared by this method has low cost, large specific surface area and pore volume, and high sulfur capacity when used for SO2 adsorption.

[0004] To achieve the above objectives, the first aspect of this disclosure provides a method for preparing sludge-based biochar adsorbent materials, the method comprising the following steps:

[0005] (1) The municipal sludge was subjected to ultrasonic treatment to obtain pretreated sludge;

[0006] (2) After mixing the pretreated sludge with the modifier, carbonize it under an inert atmosphere to obtain carbonized sludge base.

[0007] (3) The carbonized sludge base and magnesium-rich ore are mixed with an acidic reagent and impregnated.

[0008] (4) Add an amination reagent to the reaction system after impregnation treatment to carry out an amination reaction.

[0009] Optionally, step (1) further includes: first drying, grinding and sieving the ultrasonically treated sludge to obtain the pretreated sludge;

[0010] The conditions for ultrasonic treatment include: ultrasonic power of 40-60W and ultrasonic time of 2-3min.

[0011] Optionally, in step (2), the modifier is selected from one or more of H2SO4, H3PO4, HCl and KOH;

[0012] The carbonization treatment conditions include carbonization under an inert atmosphere, with the temperature increased to the carbonization temperature at a heating rate of 5–15 °C / min, wherein the carbonization temperature is 450–650 °C, the carbonization time is 1–6 h, preferably 1–4 h, and the heating rate is preferably 7–12 °C / min.

[0013] Optionally, in step (3), the magnesium-rich ore is selected from one or more of magnesium aluminum hydrotalcite, attapulgite and periclase;

[0014] The acidic reagent is nitric acid; the concentration of the acidic reagent is 0.1–1 mol / L.

[0015] The conditions for the impregnation treatment include: impregnation under ultrasonic conditions for a time of 10 to 30 minutes, preferably 15 to 25 minutes; and ultrasonic power of 100 to 500 W, preferably 100 to 300 W.

[0016] Optionally, in step (4), the amination reagent is selected from one or more of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and 3-aminopropyltriethoxysilane;

[0017] The amination conditions include: an amination temperature of 40–70°C, preferably 45–60°C; and an amination time of 5–20 h, preferably 8–12 h.

[0018] Optionally, step (4) further includes: adjusting the pH of the impregnated reaction system to 9-11 using an alkaline reagent, and then carrying out the amination reaction, wherein the alkaline reagent includes NaOH solution and / or KOH solution, and the concentration of the alkaline reagent is 3-6 mol / L.

[0019] Optionally, relative to 100 kg of municipal sludge, the amount of the modifier is 1–15 kg, the amount of the magnesium-rich ore is 20–240 kg, the amount of the acidic reagent is 260–1100 kg, and the amount of the amination reagent is 10–150 kg; preferably, relative to 100 kg of municipal sludge, the amount of the modifier is 3–12 kg, the amount of the magnesium-rich ore is 25–210 kg, the amount of the acidic reagent is 300–1050 kg, and the amount of the amination reagent is 20–110 kg.

[0020] Optionally, the method further includes: filtering the system after the amination reaction, washing the filtered solid with water until the pH of the filtrate is neutral, and performing a second drying.

[0021] The second aspect of this disclosure provides a sludge-based biochar adsorbent material prepared by the method described in the first aspect of this disclosure, wherein the sludge-based biochar adsorbent material has a specific surface area of ​​780–1300 m². 2 / g, pore volume 0.5~0.8cm 3 / g.

[0022] This disclosure provides, in a third aspect, the sludge-based biochar adsorbent material described in the second aspect of this disclosure for adsorbing SO2.

[0023] Through the above technical solution, this disclosure obtains a synergistic sludge-based biochar adsorbent material by subjecting municipal sludge to ultrasonic pretreatment, carbonization modification, impregnation treatment, and amination reaction. This adsorbent material has a large specific surface area and pore volume, and can be used to adsorb SO2 with a high sulfur capacity. The method of this disclosure is clean, has low energy consumption, and has both economic and environmental benefits; it effectively increases the metal loading and degree of amination, thereby improving the SO2 adsorption capacity.

[0024] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Detailed Implementation

[0025] The following detailed description, in conjunction with specific embodiments of this disclosure, is provided. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of this disclosure.

[0026] The first aspect of this disclosure provides a method for preparing sludge-based biochar adsorbent materials, the method comprising the following steps:

[0027] (1) The municipal sludge was subjected to ultrasonic treatment to obtain pretreated sludge;

[0028] (2) After mixing the pretreated sludge with the modifier, carbonize it under an inert atmosphere to obtain carbonized sludge base.

[0029] (3) The carbonized sludge base and magnesium-rich ore are mixed with an acidic reagent and impregnated.

[0030] (4) Add an amination reagent to the reaction system after impregnation treatment to carry out an amination reaction.

[0031] This disclosed method uses municipal sewage sludge as raw material, aligning with the concept of waste utilization. It involves ultrasonic pretreatment, carbonization, metal loading, and amination modification of the municipal sewage sludge. During the reaction, an ultrasonic-assisted method is employed, utilizing the cavitation effect of ultrasound to break up sludge particles, improving subsequent reaction efficiency, enhancing mass transfer between substances, reducing reaction energy consumption, effectively increasing the metal loading rate and amination degree, and further enhancing the adsorption capacity for SO2. The synergistic sludge-based biochar SO2 adsorbent prepared by this method has a large specific surface area and pore volume, a clean preparation process, and low energy consumption, offering both economic and environmental benefits.

[0032] According to one embodiment of this disclosure, step (1) further includes: subjecting the ultrasonically treated sludge to a first drying, grinding, and sieving process to obtain the pretreated sludge; the ultrasonic treatment conditions include: ultrasonic power of 40-60W and ultrasonic time of 2-3 minutes. This disclosure does not specifically limit the first drying conditions; they can be conventional drying temperatures in the art, drying the water in the sludge to a constant weight. For example, the first drying temperature can be 80-120°C, preferably 100-110°C. The above embodiment is beneficial for increasing the contact area between the sludge particles and subsequent reaction reagents, thereby improving the efficiency of subsequent reactions.

[0033] According to one embodiment of this disclosure, in step (2), the modifier is selected from one or more of H2SO4, H3PO4, HCl, and KOH; the carbonization treatment conditions include carbonization under an inert atmosphere, with a heating rate of 5–15 °C / min to reach the carbonization temperature, wherein the carbonization temperature is 450–650 °C, and the carbonization time is 1–6 h, preferably 1–4 h; the heating rate is preferably 7–12 °C / min. The inert atmosphere includes one or more of nitrogen and rare gases, preferably nitrogen. The above embodiment is beneficial for obtaining biochar materials with large specific surface area and pore volume.

[0034] According to one embodiment of this disclosure, step (2) further includes sequentially rinsing the carbonized solid with ethanol, hydrochloric acid, and water, followed by a third drying to obtain the carbonized sludge base; the concentration of the hydrochloric acid is 0.05–1 mol / L, preferably 0.05–0.2 mol / L; the temperature of the third drying can be 50–80°C, preferably 55–65°C. The above embodiment is beneficial for removing oily substances from the surface of the biochar material, and further facilitates the modification treatment of the biochar material.

[0035] According to one embodiment of this disclosure, in step (3), the magnesium-rich ore is selected from one or more of magnesium aluminum hydrotalcite, attapulgite, and periclase; the acidic reagent is nitric acid; the concentration of the acidic reagent is 0.1–1 mol / L, preferably 0.1–0.4 mol / L; the impregnation treatment conditions include: impregnation under ultrasonic conditions for 10–30 min, preferably 15–25 min, and ultrasonic power of 100–500 W, preferably 100–300 W. The above embodiment is beneficial for improving the degree of metal loading on biochar materials, further enhancing the adsorption capacity of sludge-based adsorbent materials for SO2.

[0036] According to one embodiment of this disclosure, the amination reagent is selected from one or more of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and 3-aminopropyltriethoxysilane; the amination conditions include: an amination temperature of 40–70°C, preferably 45–60°C; and an amination time of 5–20 h, preferably 8–12 h. In one embodiment, step (4) further includes: adjusting the pH of the impregnated reaction system to 9–11 using an alkaline reagent before carrying out the amination reaction; the alkaline reagent includes NaOH solution and / or KOH solution, and the concentration of the alkaline reagent is 3–6 mol / L. The above embodiments are beneficial for increasing the degree of amination modification of sludge-based biochar materials and further improving their adsorption capacity for SO2.

[0037] According to one embodiment of this disclosure, relative to 100 kg of municipal sludge, the amount of the modifier is 1-15 kg, the amount of the magnesium-rich ore is 20-240 kg, the amount of the acidic reagent is 260-1100 kg, and the amount of the amination reagent is 10-150 kg; preferably, relative to 100 kg of municipal sludge, the amount of the modifier is 3-12 kg, the amount of the magnesium-rich ore is 25-210 kg, the amount of the acidic reagent is 300-1050 kg, and the amount of the amination reagent is 20-110 kg. The above embodiments are beneficial for obtaining sludge-based biochar adsorbent materials with large specific surface area and pore structure, resulting in higher sulfur capacity when used for SO2 adsorption.

[0038] According to one embodiment of this disclosure, the moisture content of the municipal sludge can be 10% to 30%. The moisture content of the municipal sludge refers to the mass percentage concentration of water in the municipal sludge. This embodiment is advantageous for obtaining sludge-based biochar adsorbent materials with a large specific surface area and pore structure, resulting in higher sulfur capacity when used for SO2 adsorption.

[0039] According to one embodiment of this disclosure, the method further includes: filtering the system after the amination reaction, washing the filtered solid with water until the pH of the filtrate after washing is neutral, and performing a second drying; this disclosure does not specifically limit the second drying, and it can be a conventional drying temperature and time in the art, for example, the temperature of the second drying can be 100-110°C.

[0040] A second aspect of this disclosure provides a sludge-based biochar adsorbent material prepared by the method described in the first aspect of this disclosure, wherein the sludge-based biochar adsorbent material has a specific surface area of ​​780–1300 m². 2 / g, pore volume 0.5~0.8cm 3 / g.

[0041] A third aspect of this disclosure provides the sludge-based biochar adsorbent material described in the second aspect of this disclosure for adsorbing SO2.

[0042] The present disclosure will be further illustrated by the following examples, but the present disclosure is not limited thereto.

[0043] Unless otherwise specified, all other chemical reagents used in the examples are commercially available products.

[0044] Example 1

[0045] The method in this embodiment includes the following steps:

[0046] (1) Add 100 kg of municipal sludge (moisture content of 25%) to an ultrasonic reactor and treat it for 2.5 min under 40 W ultrasonic power. Then transfer it to a constant temperature oven and dry it at 105 °C to constant weight. Take it out, grind it, and pass it through a 100 mesh sieve to obtain the pretreated municipal sludge.

[0047] (2) The pretreated municipal sludge was mixed evenly with 10 kg of H2SO4 and then transferred into a tube furnace. Under N2 atmosphere, the temperature was increased to 500℃ at a heating rate of 10℃ / min and carbonized for 2 h. The sludge was then removed and rinsed several times with anhydrous ethanol, 0.1 mol / L hydrochloric acid and distilled water, and then transferred to an oven at 60℃ to dry to constant weight to obtain carbonized sludge base.

[0048] (3) Pass the crushed 200kg attapulgite through a 100-mesh sieve and disperse it in 650kg of 0.2mol / L dilute nitric acid. Add the carbonized sludge base obtained in step (2) and then stir and react for 20min under 150W ultrasonic impregnation.

[0049] (4) Add 5 mol / L sodium hydroxide to the reaction system after impregnation treatment to adjust the pH value of the system to 10, add 40 kg tetraethylenepentamine, stir for 30 min, heat to 55℃ and continue to react for 8 h, filter, wash with water until neutral, and dry at 105℃ to obtain sludge-based biochar adsorbent material.

[0050] Example 2

[0051] The method in this embodiment includes the following steps:

[0052] (1) Add 200 kg of municipal sludge to an ultrasonic reactor and treat it for 3 min under 50 W ultrasonic power. Then transfer it to a constant temperature oven and dry it at 105 °C until constant weight. Take it out, grind it, and pass it through a 100 mesh sieve to obtain pretreated municipal sludge.

[0053] (2) The pretreated municipal sludge was mixed evenly with 6 kg KOH and then transferred into a tube furnace. Under N2 atmosphere, the temperature was raised to 650℃ at a heating rate of 10℃ / min and carbonized for 2 h. The sludge was then removed and rinsed several times with anhydrous ethanol, 0.1 mol / L hydrochloric acid and distilled water, and then transferred to an oven at 60℃ to dry to constant weight to obtain carbonized sludge base.

[0054] (3) Disperse 50kg of crushed magnesium aluminum hydrotalcite and 50kg of 100-mesh sieve into 600kg of 0.2mol / L dilute nitric acid, add the carbonized sludge base obtained in step (2), and then stir and react for 15min under 200W ultrasonic impregnation.

[0055] (4) Add 5 mol / L sodium hydroxide to the reaction system after impregnation treatment to adjust the pH value of the system to 10, add 94 kg of triethylenetetramine, stir for 30 min, heat to 55℃ and continue to react for 9 h, filter, wash with water until neutral, and dry at 105℃ to obtain sludge-based biochar adsorbent material.

[0056] Example 3

[0057] The method in this embodiment includes the following steps:

[0058] (1) Add 80 kg of municipal sludge to an ultrasonic reactor and treat it for 2.5 min at 55 W ultrasonic power. Then transfer it to a constant temperature oven and dry it at 105 °C until constant weight. Take it out, grind it, and pass it through a 100 mesh sieve to obtain pretreated municipal sludge.

[0059] (2) The pretreated municipal sludge was mixed evenly with 7 kg of H3PO4 and then transferred into a tube furnace. Under N2 atmosphere, the temperature was raised to 550℃ at a heating rate of 10℃ / min and carbonized for 2 hours. The sludge was then removed and rinsed several times with anhydrous ethanol, 0.1 mol / L hydrochloric acid and distilled water, and then transferred to an oven at 60℃ to dry to constant weight to obtain carbonized sludge base.

[0060] (3) Pass 50 kg of crushed periclase through a 100-mesh sieve and disperse it in 820 kg of 0.2 mol / L dilute nitric acid. Add the carbonized sludge base obtained in step (2) and then stir and react for 20 min under 250 W ultrasonic impregnation.

[0061] (4) Add 5 mol / L sodium hydroxide to the reaction system after impregnation treatment to adjust the pH value of the system to 10, add 20 kg diethylenetriamine and 23 kg triethylenetetramine, stir the reaction for 30 min, raise the temperature to 55℃ and continue the reaction for 11 h, filter, wash with water until neutral, and dry at 105℃ to obtain sludge-based biochar SO2 adsorption material product.

[0062] Example 4

[0063] The method in this embodiment includes the following steps:

[0064] (1) Add 120 kg of municipal sludge to an ultrasonic reactor and treat it for 2 min at 45 W ultrasonic power. Then transfer it to a constant temperature oven and dry it at 105 °C until constant weight. Take it out, grind it, and pass it through a 100 mesh sieve to obtain the pretreated municipal sludge.

[0065] (2) The pretreated municipal sludge was mixed evenly with 2.5 kg H2SO4 and 2.5 kg HCl and then transferred to a tube furnace. Under N2 atmosphere, the temperature was raised to 480℃ at a heating rate of 10℃ / min and carbonized for 2 hours. The sludge was then removed and rinsed several times with anhydrous ethanol, 0.1 mol / L hydrochloric acid and distilled water, and then transferred to an oven at 60℃ to dry to constant weight to obtain carbonized sludge base.

[0066] (3) Pass 100 kg of crushed magnesium aluminum hydrotalcite and 45 kg of attapulgite through a 100-mesh sieve and disperse them in 700 kg of 0.2 mol / L dilute nitric acid. Add the carbonized sludge base obtained in step (2) and then stir and react for 18 min under 300 W ultrasonic impregnation.

[0067] (4) Add 5 mol / L sodium hydroxide to the reaction system after impregnation treatment to adjust the pH value of the system to 10, add 15 kg of triethylenetetramine and 15 kg of tetraethylenepentamine, stir the reaction for 30 min, raise the temperature to 55℃ and continue the reaction for 12 h, filter, wash with water until neutral, and dry at 105℃ to obtain sludge-based biochar adsorbent material.

[0068] Example 5

[0069] The method in this embodiment includes the following steps:

[0070] (1) Add 90 kg of municipal sludge to an ultrasonic reactor and treat it at 55 W ultrasonic power for 2.5 min. Then transfer it to a constant temperature oven and dry it at 105 °C until constant weight. Take it out, grind it, and pass it through a 100 mesh sieve to obtain pretreated municipal sludge.

[0071] (2) The pretreated municipal sludge was mixed evenly with 10 kg of H3PO4 and then transferred into a tube furnace. Under N2 atmosphere, the temperature was raised to 600℃ at a heating rate of 10℃ / min and carbonized for 2 h. The sludge was then removed and rinsed several times with anhydrous ethanol, 0.1 mol / L hydrochloric acid and distilled water, and then transferred to an oven at 60℃ to dry to constant weight to obtain carbonized sludge base.

[0072] (3) Pass 120 kg of crushed magnesium aluminum hydrotalcite through a 100-mesh sieve and disperse it in 690 kg of 0.2 mol / L dilute nitric acid. Add the carbonized sludge-based biochar obtained in step (2) and then stir and react for 20 min under 250 W ultrasonic impregnation.

[0073] (4) Add 5 mol / L sodium hydroxide to the reaction system after impregnation treatment to adjust the pH value of the system to 10, add 90 kg of 3-aminopropyltriethoxysilane, stir for 30 min, heat to 55℃ and continue to react for 10 h, filter, wash with water until neutral, and dry at 105℃ to obtain sludge-based biochar adsorbent material.

[0074] Example 6

[0075] The method in this embodiment includes the following steps:

[0076] (1) Add 100kg of municipal sludge to an ultrasonic reactor and treat it for 2.5min under 40W ultrasonic power. Then transfer it to a constant temperature oven and dry it at 105℃ to constant weight. Take it out, grind it, and pass it through a 100-mesh sieve to obtain the pretreated municipal sludge.

[0077] (2) The pretreated municipal sludge was mixed evenly with 10 kg of H2SO4 and then transferred into a tube furnace. Under N2 atmosphere, the temperature was increased to 500℃ at a heating rate of 10℃ / min and carbonized for 2 h. The sludge was then removed and rinsed several times with anhydrous ethanol, 0.1 mol / L hydrochloric acid and distilled water, and then transferred to an oven at 60℃ to dry to constant weight to obtain carbonized sludge base.

[0078] (3) Pass the crushed 200kg attapulgite through a 100-mesh sieve and disperse it in 650kg of 0.2mol / L dilute nitric acid. Then, stir the carbonized sludge base obtained in step (2) for 20min.

[0079] (4) Add 5 mol / L sodium hydroxide to the reaction system after impregnation treatment to adjust the pH value of the system to 10, add 40 kg tetraethylenepentamine, stir for 30 min, heat to 55℃ and continue to react for 8 h, filter, wash with water until neutral, and dry to obtain sludge-based biochar adsorbent material.

[0080] Comparative Example 1

[0081] This comparative method includes the following steps:

[0082] (1) Transfer 100kg of municipal sludge to a constant temperature oven and dry it at 105℃ to constant weight. Take it out, grind it, and pass it through a 100-mesh sieve to obtain pretreated municipal sludge.

[0083] (2) The pretreated municipal sludge was mixed evenly with 10 kg of H2SO4 and then transferred into a tube furnace. Under N2 atmosphere, the temperature was increased to 500℃ at a heating rate of 10℃ / min and carbonized for 2 h. The sludge was then removed and rinsed several times with anhydrous ethanol, 0.1 mol / L hydrochloric acid and distilled water, and then transferred to an oven at 60℃ to dry to constant weight to obtain carbonized sludge base.

[0084] (3) Pass the crushed 200kg attapulgite through a 100-mesh sieve and disperse it in 650kg of 0.2mol / L dilute nitric acid. Add the carbonized sludge-based biochar obtained in step (2) and then stir and react for 20min under 150W ultrasonic impregnation.

[0085] (4) Add 5 mol / L sodium hydroxide to the reaction system after impregnation treatment to adjust the pH value of the system to 10, add 40 kg tetraethylenepentamine, stir for 30 min, heat to 55℃ and continue to react for 8 h, filter, wash with water until neutral, and dry to obtain sludge-based biochar adsorbent material.

[0086] Comparative Example 2

[0087] The method of Comparative Example 1 is the same as that of Example 1, except that an amination reaction is not performed; the method of this comparative example includes the following steps:

[0088] (1) Add 100kg of municipal sludge to an ultrasonic reactor and treat it for 2.5min under 40W ultrasonic power. Then transfer it to a constant temperature oven and dry it at 105℃ to constant weight. Take it out, grind it, and pass it through a 100-mesh sieve to obtain the pretreated municipal sludge.

[0089] (2) The pretreated municipal sludge was mixed evenly with 10 kg of H2SO4 and then transferred into a tube furnace. Under N2 atmosphere, the temperature was increased to 500℃ at a heating rate of 10℃ / min and carbonized for 2 h. The sludge was then removed and rinsed several times with anhydrous ethanol, 0.1 mol / L hydrochloric acid and distilled water, and then transferred to an oven at 60℃ to dry to constant weight to obtain carbonized sludge base.

[0090] (3) Pass 200 kg of crushed attapulgite through a 100-mesh sieve and disperse it in 650 kg of 0.2 mol / L dilute nitric acid. Add the carbonized sludge base obtained in step (2) and stir the reaction under 150 W ultrasonic impregnation for 20 min. Add 5 mol / L sodium hydroxide to the reaction system after impregnation to adjust the pH value of the system to 10, stir the reaction for 30 min, raise the temperature to 55℃ and continue the reaction for 8 h. Filter, wash with water until neutral, and dry to obtain sludge-based biochar adsorbent material.

[0091] Performance testing

[0092] (1) Specific surface area and pore volume determination

[0093] The specific surface area (BET) of the sludge-based biochar adsorbent materials obtained in Examples 1-6 and Comparative Examples 1-2 was analyzed using a Micromeritics ASAP2020 HD88 physical adsorption instrument. The test results are shown in Table 1.

[0094] (2) Sulfur capacity determination

[0095] The adsorbent material was sieved through a 200-mesh sieve, with a mass of 0.5g. The desulfurization temperature was 100℃, and the simulated flue gas consisted of 5% (volume fraction) O2, 5% (volume fraction) H2O, and SO2, with N2 used as the carrier gas. The SO2 concentration in the inlet and outlet mixed gas and the sulfur content of the samples before and after desulfurization were detected using an online infrared flue gas analyzer (Gasboard-3000, Wuhan Sifang Optoelectronics Technology Co., Ltd.). The sulfur capacity was taken as the adsorption capacity when the SO2 removal rate η ≥ 80%. The test results are shown in Table 1.

[0096] Table 1

[0097] Example 1 1157.1 0.73 220.4 Example 2 795.6 0.57 180.4 Example 3 854.7 0.63 193.7 Example 4 1245.6 0.72 205.4 Example 5 969.4 0.64 236.4 Example 6 810.4 0.59 177.1 Comparative Example 1 815.6 0.54 147.4 Comparative Example 2 897.5 0.61 152.9

[0098] As shown in Table 1, the sludge-based biochar adsorbent material obtained by the method of this disclosure has a large specific surface area and pore volume, and exhibits a high sulfur capacity when used for SO2 adsorption. A comparison of Examples 1 and 6 shows that, under the impregnation treatment conditions of this disclosure, the sludge-based biochar adsorbent material obtained by the method of this disclosure has a high sulfur capacity.

[0099] The preferred embodiments of this disclosure have been described in detail above. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0100] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0101] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A method for preparing sludge-based biochar adsorbent materials, characterized in that, The method includes the following steps: (1) The municipal sludge was subjected to ultrasonic treatment to obtain pretreated sludge; (2) After mixing the pretreated sludge with the modifier, carbonize it under an inert atmosphere to obtain carbonized sludge base. (3) The carbonized sludge-based material and magnesium-rich ore are mixed with an acidic reagent and impregnated. (4) After adjusting the pH of the reaction system after impregnation to 9-11 using an alkaline reagent, add an amination reagent to carry out the amination reaction.

2. The method according to claim 1, wherein, Step (1) further includes: first drying, grinding and sieving the ultrasonically treated sludge to obtain the pretreated sludge; The conditions for ultrasonic treatment include: ultrasonic power of 40~60 W and ultrasonic time of 2~3 min.

3. The method according to claim 1, wherein, In step (2), the modifier is selected from one or more of H2SO4, H3PO4, HCl and KOH; The carbonization treatment conditions include carbonization under an inert atmosphere, with a heating rate of 5~15℃ / min to the carbonization temperature, wherein the carbonization temperature is 450~650℃ and the carbonization time is 1~6h.

4. The method according to claim 3, wherein, The carbonization time is 1-4 hours; the heating rate is 7-12℃ / min.

5. The method according to claim 1, wherein, In step (3), the magnesium-rich ore is selected from one or more of magnesium aluminum hydrotalcite, attapulgite and periclase; The acidic reagent is nitric acid; The concentration of the acidic reagent is 0.1~1 mol / L; The conditions for the impregnation treatment include: impregnation under ultrasonic conditions for 10-30 minutes; and ultrasonic power of 100-500W.

6. The method according to claim 5, wherein, The immersion time is 15-25 minutes; the ultrasonic power is 100-300W.

7. The method according to claim 1, wherein, In step (4), the amination reagent is selected from one or more of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and 3-aminopropyltriethoxysilane; The amination conditions include: an amination temperature of 40~70℃ and an amination time of 5~20h.

8. The method according to claim 7, wherein, The amination conditions include: an amination temperature of 45~60℃ and an amination time of 8~12h.

9. The method according to claim 1, wherein, The alkaline reagent includes NaOH solution and / or KOH solution, and the concentration of the alkaline reagent is 3~6 mol / L.

10. The method according to claim 1, wherein, For 100 kg of municipal sludge, the amount of the modifier is 1-15 kg, the amount of the magnesium-rich ore is 20-240 kg, the amount of the acidic reagent is 260-1100 kg, and the amount of the amination reagent is 10-150 kg.

11. The method according to claim 10, wherein, Relative to 100 kg of municipal sludge, the amount of the modifier is 3-12 kg, the amount of the magnesium-rich ore is 25-210 kg, the amount of the acidic reagent is 300-1050 kg, and the amount of the amination reagent is 20-110 kg.

12. The method according to claim 1, wherein, The method further includes: filtering the system after the amination reaction, washing the filtered solid with water until the pH of the filtrate is neutral, and performing a second drying.

13. The sludge-based biochar adsorbent material prepared by the method according to any one of claims 1 to 12, characterized in that, The specific surface area of ​​the sludge-based biochar adsorbent material is 780~1300 m². 2 / g, pore volume 0.5~0.8cm 3 / g.

14. The application of the sludge-based biochar adsorbent material according to claim 13 in the adsorption of SO2.