A sulfonated carbon-modified waste carbon composite material, a preparation method and application thereof

Abstract

The application discloses sulfonated carbon-modified waste carbon composite material and a preparation method and application thereof, and belongs to the technical field of wastewater treatment. The preparation method of the composite material comprises the following steps: mixing a sulfonating agent solution and carbon-containing raw materials, and then performing heating reaction to obtain sulfonated carbon; performing alkaline activator treatment on waste carbon after the waste carbon is treated, and then performing heat treatment to obtain modified waste carbon; mixing the sulfonated carbon and the modified waste carbon, soaking the mixture in an acid solution, and then mixing the mixture with a binder to obtain sulfonated carbon-modified waste carbon composite material. The sulfonated carbon and the modified waste carbon are compounded, the waste is changed into treasure to realize resource utilization and waste carbon regeneration, the composite material has a "chemical adsorption-physical adsorption" double-channel synergistic effect, has good adsorption performance on various pollutants in wastewater, and the application also has the advantages of simple operation, low cost and the like.

Description

Technical Field

[0001] This invention relates to a sulfonated carbon-modified waste carbon composite material, its preparation method and application, belonging to the field of wastewater treatment technology. Background Technology

[0002] Sulfonated carbon is a carbonaceous material with unique surface chemistry. Its molecular structure is rich in carbon, oxygen, and sulfur, and modified with abundant oxygen-containing functional groups (such as -SO3H, -COOH, and -OH). This material can be prepared from various raw materials, including natural organic matter, agricultural waste biomass, or industrial waste carbon, and exhibits significant advantages in wastewater treatment. As an adsorbent for wastewater treatment, sulfonated carbon exhibits three key advantages in its surface properties: 1. Oxygen-containing groups impart strong hydrophilicity, enhancing aqueous phase diffusion efficiency; 2. The reduced zero-point potential results in a negatively charged surface in moderately alkaline environments, enabling efficient capture of cationic pollutants through electrostatic interactions; 3. Functional groups such as -SO3H can form coordination bonds with pollutants such as heavy metals, achieving chemical complexation adsorption. These characteristics enable sulfonated carbon to achieve adsorption capacities of 4-77 mg / g for cationic pollutants, 200-1250 mg / g for methylene blue, and heavy metal ions (such as Pb). 2+ and Cd 2+ The adsorption capacity of sulfonated carbon (such as hydroxyl groups) can reach 50-400 mg / g. Sulfonated carbon is very effective in treating wastewater with high concentrations of cationic pollutants.

[0003] However, existing sulfonated carbon wastewater treatment processes face severe performance bottlenecks: While the sulfonated carbon prepared by the one-step carbonization / sulfonation method—which directly reacts concentrated sulfuric acid or fuming sulfuric acid with carbohydrates—is rich in functional groups (acid density 2.1-7.3 mmol / g), its specific surface area is generally below 100 m². 2 / g, far lower than pyrolytic biochar (50-800 m 2 / g) and commercial activated carbon (>1000 m 2 The adsorption rate of carbon per gram (g) results in a physical adsorption efficiency for organic pollutants (such as polycyclic aromatic hydrocarbons, polyphenols, and highly unsaturated compounds) that is far lower than that of pyrolytic carbon and activated carbon. CN109289870A discloses a sulfonated carbon and its preparation method, which uses a three-step method to prepare sulfonated carbon: first, acid hydrolysis of carbohydrates at 180-240 °C, then high-temperature pyrolysis at 350-500 °C, and finally secondary sulfonation at 120-150 °C. Although this method can obtain porous sulfonated carbon with high acid density, it suffers from problems such as an excessively long process chain, large dosage of sulfonating agent, and high operating costs. However, if simplified to a one-step carbonization / sulfonation method, it faces the drawback of excessively low porosity and specific surface area of ​​the product.

[0004] Furthermore, sulfonated carbon that has become saturated with adsorption will form solid waste if it is not regenerated. Existing regeneration technologies mainly include pyrolysis regeneration and chemical reagent regeneration, but both have significant shortcomings: pyrolysis regeneration (temperature > 450 ℃) causes a large number of oxygen-containing functional groups (especially -SO3H and -COOH) on the surface of sulfonated carbon to decompose, severely weakening its chemical adsorption capacity; while the strong acids and alkalis used in chemical reagent regeneration not only corrode and destroy the carbon skeleton structure, but may also cause secondary pollution and increase process costs. These technological limitations severely restrict the large-scale engineering application of sulfonated carbon.

[0005] Therefore, in view of the shortcomings of existing technologies in terms of porous structure construction, process complexity and regeneration performance, there is an urgent need to develop a simple and low-cost preparation process for composite sulfonated carbon materials. Summary of the Invention

[0006] To address the aforementioned technical problems, the present invention aims to provide a sulfonated carbon-modified waste carbon composite material, its preparation method, and its application. This invention, by combining sulfonated carbon and modified waste carbon, achieves resource utilization and waste carbon regeneration while turning waste into treasure. Simultaneously, the composite material exhibits a synergistic effect of "chemical adsorption-physical adsorption" dual channels, demonstrating good adsorption performance for various pollutants in wastewater. Furthermore, this invention also boasts advantages such as simple operation and low cost.

[0007] To achieve the above objectives, the first aspect of the present invention provides a method for preparing a sulfonated carbon-modified waste carbon composite material, comprising the following steps:

[0008] Step 1, Preparation of sulfonated carbon:

[0009] A solution of sulfonating agent is mixed with a carbon-containing raw material and then heated to react, yielding sulfonated carbon.

[0010] Step 2, Modification of waste charcoal:

[0011] The waste carbon after wastewater treatment is first treated with an alkaline activator and then subjected to heat treatment to obtain modified waste carbon.

[0012] Step 3, Preparation of composite materials:

[0013] The sulfonated carbon obtained in step 1 and the modified waste carbon obtained in step 2 are mixed, soaked in an acid solution, and then mixed with a binder to obtain the sulfonated carbon-modified waste carbon composite material.

[0014] According to a specific embodiment of the present invention, preferably, in step 1, the heating reaction temperature is 160-250°C and the time is 4-24 h.

[0015] According to a specific embodiment of the present invention, preferably, in step 1, the carbon-containing raw material includes agricultural waste biomass and / or carbohydrates, etc. Specifically, the agricultural waste biomass includes one or more of rice husks, straw, and fruit peels, etc.; the carbohydrates include one or more of glucose, fructose, xylose, sucrose, and cellulose, etc.

[0016] According to a specific embodiment of the present invention, preferably, in step 1, the sulfonating agent in the solution of the sulfonating agent includes one or more of sulfuric acid, toluenesulfonic acid, sulfosalicylic acid and chlorosulfonic acid.

[0017] According to a specific embodiment of the present invention, preferably, in step 1, the mass ratio of the sulfonating agent in the solution of the sulfonating agent to the carbon-containing raw material is (4-20):1.

[0018] According to a specific embodiment of the present invention, preferably, in step 1, the specific surface area of ​​the sulfonated carbon is 6-14 m². 2 / g, pore volume is 0.01-0.025 cm³ / g. 3 / g.

[0019] According to a specific embodiment of the present invention, preferably, in step 2, the waste carbon after treating the wastewater includes waste carbon formed by treating the wastewater with sulfonated carbon obtained in step 1, and / or waste carbon formed by treating the wastewater with sulfonated carbon-modified waste carbon composite material obtained in step 3, etc.

[0020] According to a specific embodiment of the present invention, preferably, in step 2, the alkaline activator treatment includes: soaking the waste carbon in an alkaline solution for 1-4 hours.

[0021] According to a specific embodiment of the present invention, preferably, in step 2, the alkaline solution comprises a mixed solution of ammonium nitrate, sodium hydroxide and potassium hydroxide; in the mixed solution, the mass fraction of ammonium nitrate is 5.0-15.0%, the mass fraction of sodium hydroxide is 1.0-5.0%, and the mass fraction of potassium hydroxide is 1.0-7.0%.

[0022] According to a specific embodiment of the present invention, preferably, in step 2, the ratio of the waste carbon to the alkaline solution is (50-200) g: 1 L.

[0023] According to a specific embodiment of the present invention, preferably, in step 2, the heat treatment temperature is 400-800°C and the time is 15-30 min. More preferably, the heat treatment is carried out in a protective gas atmosphere, and the flow rate of the protective gas is 100-200 mL / min.

[0024] According to a specific embodiment of the present invention, preferably, in step 2, the specific surface area of ​​the modified waste carbon is 180-500 m². 2 / g, pore volume is 0.1-0.2 cm³ 3 / g.

[0025] According to a specific embodiment of the present invention, preferably, in step 3, the mass ratio of the sulfonated carbon to the modified waste carbon is (1-5):1.

[0026] According to a specific embodiment of the present invention, preferably, in step 3, the acid solution comprises a dilute nitric acid solution. More preferably, the mass concentration of the acid solution is 1-5%.

[0027] According to a specific embodiment of the present invention, preferably, in step 3, the soaking time in the acid solution is 10-30 minutes.

[0028] According to a specific embodiment of the present invention, preferably, in step 3, mixing with the adhesive includes: adding the product soaked in the acid solution to the adhesive solution, sonicating for 15-30 min, and then letting it stand for 2-6 h.

[0029] According to a specific embodiment of the present invention, preferably, in step 3, the mass ratio of the product soaked in the acid solution to the adhesive in the adhesive solution is (20-50):1.

[0030] According to a specific embodiment of the present invention, preferably, in step 3, the adhesive in the adhesive solution includes carboxymethyl cellulose, etc. More preferably, the mass concentration of the adhesive solution is 2-5%.

[0031] The second aspect of the present invention provides a sulfonated carbon-modified waste carbon composite material, which is prepared by the above-described method for preparing the sulfonated carbon-modified waste carbon composite material.

[0032] According to a specific embodiment of the present invention, preferably, the specific surface area of ​​the sulfonated carbon-modified waste carbon composite material is 50-220 m². 2 / g, with a pore volume of 0.025-0.13 cm³. 3 / g.

[0033] The third aspect of this invention provides the application of the above-mentioned sulfonated carbon-modified waste carbon composite material in wastewater treatment.

[0034] According to a specific embodiment of the present invention, preferably, the amount of the sulfonated carbon-modified waste carbon composite material added to the wastewater is 2.5-20 g / L.

[0035] According to a specific embodiment of the present invention, preferably, the application includes the following steps: adding the sulfonated carbon-modified waste carbon composite material to wastewater and treating it at 25-35 ℃ and a shaking speed of 180-240 rpm for 24-36 h.

[0036] According to a specific embodiment of the present invention, preferably, the ammonia nitrogen concentration in the wastewater is 50-500 mg / L, the DOC (soluble organic carbon) concentration is 200-1500 mg / L, and the total metal ion concentration is 10-1500 mg / L.

[0037] The present invention has at least the following beneficial technical effects:

[0038] This invention employs a one-step carbonization / sulfonation process to prepare sulfonated carbon, and then modifies the waste carbon using an alkaline activator followed by heat treatment. The sulfonated carbon is then composited with the modified waste carbon, fully utilizing the advantages of sulfonated carbon's rich content of -SO3H, -COOH, and -OH groups, and the modified waste carbon's high specific surface area. Furthermore, immersing the mixture in an acid solution further expands the pores and maintains and enhances the density of oxygen-containing groups on the surface. Finally, it is mixed with a binder to prepare a sulfonated carbon-modified waste carbon composite material with a well-developed pore structure, high specific surface area, and rich surface chemical activity. This invention not only transforms waste carbon into a valuable resource for resource utilization and regeneration, but also effectively solves the problems of easy decomposition of functional groups and easy destruction of the carbon skeleton in traditional waste carbon regeneration processes, transforming the defects of adsorption-saturated waste carbon into the advantages of a porous structure. The composite material of this invention exhibits a synergistic effect of "chemical adsorption-physical adsorption," retaining the selectivity of functional groups such as sulfonated groups for metal cations while significantly increasing capacity due to the high specific surface area. The composite material of this invention exhibits good adsorption performance for various pollutants in wastewater and can be recycled, meeting the treatment requirements for complex wastewater containing high concentrations of ammonia nitrogen, high salinity, and high DOC organic matter. Furthermore, this invention also has advantages such as simple operation, low cost, and low energy consumption. Attached Figure Description

[0039] Figure 1 This is a schematic flowchart of the preparation method of the sulfonated carbon-modified waste carbon composite material in Example 1.

[0040] Figure 2 This is a scanning electron microscope image of the sulfonated carbon obtained in step 1 of Example 1.

[0041] Figure 3 This is a scanning electron microscope image of the waste carbon used in step 2 of Example 1.

[0042] Figure 4 This is a scanning electron microscope image of the waste carbon used in step 2 of Example 1.

[0043] Figure 5 This is a scanning electron microscope image of the waste carbon used in step 2 of Example 1.

[0044] Figure 6 This is a scanning electron microscope image of the modified waste carbon obtained in step 2 of Example 1.

[0045] Figure 7 This is a scanning electron microscope image of the modified waste carbon obtained in step 2 of Example 1.

[0046] Figure 8 This is a scanning electron microscope image of the modified waste carbon obtained in step 2 of Example 1.

[0047] Figure 9 This is a scanning electron microscope image of the sulfonated carbon-modified waste carbon composite material prepared in Example 1.

[0048] Figure 10 This is a scanning electron microscope image of the sulfonated carbon-modified waste carbon composite material prepared in Example 1.

[0049] Figure 11 The curves show the removal rates of soluble organic carbon in wastewater under different addition amounts of the sulfonated carbon obtained in step 1 of Example 1, the modified waste carbon obtained in step 2, and the composite material obtained in step 3.

[0050] Figure 12 The curves show the removal rates of ammonia nitrogen in wastewater under different addition amounts of the sulfonated carbon obtained in step 1 of Example 1, the modified waste carbon obtained in step 2, and the composite material obtained in step 3.

[0051] Figure 13 This is a scanning electron microscope image of the modified sulfonated carbon obtained at a pyrolysis temperature of 400℃ in step 2 of Comparative Example 1.

[0052] Figure 14 This is a scanning electron microscope image of the modified sulfonated carbon obtained at a pyrolysis temperature of 500℃ in step 2 of Comparative Example 1.

[0053] Figure 15 This is a scanning electron microscope image of the modified sulfonated carbon obtained at 600℃ pyrolysis temperature in step 2 of Comparative Example 1.

[0054] Figure 16 This is a scanning electron microscope image of the modified sulfonated carbon obtained at 700℃ pyrolysis temperature in step 2 of Comparative Example 1. Detailed Implementation

[0055] To provide a clearer understanding of the technical features, objectives, and beneficial effects of the present invention, the present invention will now be described in detail below, but this should not be construed as limiting the scope of the invention.

[0056] It should be noted that, unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0057] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0058] It should be understood that the terms “comprising,” “including,” and / or “containing” as used herein specify the presence of the stated features, integers, steps, components, or combinations thereof, but do not exclude the presence or addition of one or more other features, integers, steps, components, or combinations thereof.

[0059] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0060] According to a specific embodiment of the first aspect of the present invention, the present invention provides a method for preparing a sulfonated carbon-modified waste carbon composite material, which includes the following steps:

[0061] Step 1, Preparation of sulfonated carbon:

[0062] A solution of sulfonating agent is mixed with a carbon-containing raw material and then heated to react, yielding sulfonated carbon.

[0063] Step 2, Modification of waste charcoal:

[0064] The waste carbon after wastewater treatment is first treated with an alkaline activator and then subjected to heat treatment to obtain modified waste carbon.

[0065] Step 3, Preparation of composite materials:

[0066] The sulfonated carbon obtained in step 1 and the modified waste carbon obtained in step 2 are mixed, soaked in an acid solution, and then mixed with a binder to obtain the sulfonated carbon-modified waste carbon composite material.

[0067] In some embodiments, in step 1, the heating reaction temperature is 160-250 °C, preferably 180-250 °C, and the time is 4-24 h, preferably 4-6 h. The heating method can be microwave heating, with a microwave power of 350-550 W / kg. Furthermore, the heating reaction can be carried out under stirring conditions, with a stirring rate of 100-200 rpm. After the heating reaction is completed, the sulfonated carbon can be obtained through washing, drying, and grinding. The washing process can begin with filtration washing with boiling water (>80 °C) to remove soluble interfering substances from the sulfonated carbon; then, it can be repeatedly washed with alternating filtration washing of boiling water and anhydrous ethanol until the filtrate pH=7, thereby removing sulfonating agents and organic residues from the pore structure and surface of the sulfonated carbon. In this step, washing with boiling water (>80 °C) immediately after the reaction is completed reduces the washing water volume by 40-60% compared to washing with room temperature water, significantly reducing the discharge of acidic wastewater, while thoroughly removing residual sulfonating agents and byproducts, resulting in pure sulfonated carbon. The drying temperature can be 90-120 ℃, and the time can be 10-15 h. There are no special restrictions on the particle size of the ground particles, as long as relatively uniform particles are formed without lumps.

[0068] In some embodiments, in step 1, the carbon-containing raw material includes agricultural waste biomass and / or carbohydrates, etc. Specifically, the agricultural waste biomass includes one or more of rice husks, straw, and fruit peels, etc.; the carbohydrates include one or more of glucose, fructose, xylose, sucrose, and cellulose, etc.

[0069] In some embodiments, in step 1, the sulfonating agent in the solution includes one or more of sulfuric acid, toluenesulfonic acid, sulfosalicylic acid, and chlorosulfonic acid. Specifically, when sulfuric acid is used as the sulfonating agent, the sulfuric acid solution includes concentrated sulfuric acid with a mass concentration of 98% and / or fuming sulfuric acid. This invention does not impose special limitations on the concentration of the sulfonating agent in the solution of other sulfonating agents, as long as the amount of solvent water is not excessive and the reaction can proceed smoothly.

[0070] According to an embodiment of the present invention, step 1 uses an inexpensive carbon source as raw material and a sulfonating agent to prepare amorphous sulfonated carbon in one step by in-situ carbonization / sulfonation, which has the advantages of simple operation, low cost and low energy consumption.

[0071] In some embodiments, in step 1, the mass ratio of the sulfonating agent to the carbon-containing raw material in the sulfonating agent solution is (4-20):1.

[0072] In some embodiments, in step 1, the specific surface area of ​​the sulfonated carbon is 6-14 m². 2 / g, pore volume is 0.01-0.025 cm³ / g. 3 / g.

[0073] In some embodiments, in step 2, the waste carbon after treating the wastewater includes waste carbon formed by treating the wastewater with sulfonated carbon obtained in step 1, and / or waste carbon formed by treating the wastewater with the sulfonated carbon-modified waste carbon composite material obtained in step 3, etc. Preferably, the wastewater contains at least NH4. + And alkali metal ions.

[0074] In some embodiments, step 2, the alkaline activator treatment includes soaking the waste carbon in an alkaline solution for 1-4 hours. The soaking can be carried out under stirring conditions, and the stirring rate can be conventionally adjusted by those skilled in the art. After soaking in the alkaline solution, solid-liquid separation and drying steps can be performed, followed by heat treatment. Solid-liquid separation can be achieved through filtration or vacuum filtration. The drying temperature and time can be conventionally adjusted by those skilled in the art.

[0075] In some embodiments, in step 2, the alkaline solution comprises a mixed solution of ammonium nitrate, sodium hydroxide, and potassium hydroxide; in the mixed solution, the mass fraction of ammonium nitrate is 5.0-15.0%, the mass fraction of sodium hydroxide is 1.0-5.0%, and the mass fraction of potassium hydroxide is 1.0-7.0%.

[0076] In some embodiments, in step 2, the ratio of the waste carbon to the alkaline solution is (50-200) g: 1 L.

[0077] In some embodiments, in step 2, the heat treatment temperature is 400-800 °C, and the time is 15-30 min. Preferably, the heat treatment is carried out in an atmosphere of flowing protective gas at a flow rate of 100-200 mL / min. The protective gas primarily serves to isolate reactive gases such as oxygen. The protective gas can be, for example, nitrogen. Furthermore, the heat treatment can be carried out in conventional equipment such as a tube furnace.

[0078] In some embodiments, in step 2, the specific surface area of ​​the modified waste carbon is 180-500 m². 2 / g, pore volume is 0.1-0.2 cm³ 3 / g.

[0079] Sulfonated carbon can be used to adsorb NH4 in wastewater. + Na + K +Pollutants such as NH4+. The surface of the saturated waste carbon is enriched with alkali metals and some alkaline species, but unreacted active sites still exist. Step 2 of this invention involves immersing the waste carbon in an alkaline activator to fully expose all active sites; subsequently, it is rapidly pyrolyzed in a tubular furnace at 400-800 °C for 15-30 min (traditional regeneration requires >450 °C for 2 h). The inventors of this invention hypothesize that this process has the following synergistic effect: + Instantaneous thermal decomposition generates gas, resulting in significant pore formation; Na + / K + Alkali metal ions are embedded into the carbon framework, forming new pores and defects during the heating process. After modification, the porosity and specific surface area of ​​the waste carbon increase significantly. The adsorbed organic pollutants are directly incorporated into the carbon network through high-temperature aromatization, avoiding secondary emissions. Through the activation-pyrolysis of this invention, the porosity and specific surface area of ​​the waste carbon are greatly improved, and the carbon recovery rate is high, realizing the high-value recycling of waste.

[0080] In some embodiments, in step 3, the mass ratio of the sulfonated carbon to the modified waste carbon is (1-5):1, preferably (2-5):1.

[0081] In some embodiments, in step 3, the acid solution comprises a dilute nitric acid solution. Preferably, the mass concentration of the acid solution is 1-5%.

[0082] In some embodiments, in step 3, the soaking time in the acid solution is 10-30 minutes. There are no special restrictions on the ratio of the mixture of sulfonated carbon and modified waste carbon to the acid solution, as long as the mixture is completely immersed in the acid solution. Briefly soaking the modified carbon and sulfonated carbon together in dilute nitric acid achieves a dual purpose: eluting free ash and metal ions, further expanding pores; and further maintaining and enhancing the oxygen-containing group density on the surface of the sulfonated carbon. After soaking in the acid solution, solid-liquid separation and washing steps can be performed before mixing with the binder. Solid-liquid separation can be achieved through filtration or vacuum filtration. Washing can be performed with water until the pH of the filtrate reaches 7.

[0083] In some embodiments, step 3, mixing with the adhesive, includes: adding the product soaked in the acid solution to the adhesive solution, ultrasonically treating for 15-30 min, and then allowing it to stand for 2-6 h. Ultrasonic treatment mainly serves to fully disperse and penetrate the adhesive into the composite material, thereby improving its adhesive effect. After standing, the sulfonated carbon-modified waste carbon composite material can be obtained through solid-liquid separation, washing, drying, and grinding. Solid-liquid separation can be achieved through filtration or vacuum filtration. Washing can be done by repeated rinsing with water. The drying temperature can be 60-80 ℃, and the drying time can be 10-15 h. There are no special restrictions on the particle size of the ground particles, as long as relatively uniform particles are formed without lumps. By uniformly compounding the two types of carbon using an adhesive at room temperature, a composite material with both a well-developed porous structure and rich surface chemical activity is obtained.

[0084] In some embodiments, in step 3, the mass ratio of the product soaked in the acid solution to the adhesive in the adhesive solution is (20-50):1.

[0085] In some embodiments, in step 3, the adhesive in the adhesive solution includes carboxymethyl cellulose, etc. Preferably, the mass concentration of the adhesive solution is 2-5%.

[0086] According to a specific embodiment of the second aspect of the present invention, the present invention provides a sulfonated carbon-modified waste carbon composite material, which is prepared by the above-described method for preparing sulfonated carbon-modified waste carbon composite material.

[0087] In some embodiments, the specific surface area of ​​the sulfonated carbon-modified waste carbon composite material is 50-220 m². 2 / g, with a pore volume of 0.025-0.13 cm³. 3 / g.

[0088] According to a specific embodiment of the third aspect of the present invention, the present invention provides the application of the above-mentioned sulfonated carbon-modified waste carbon composite material in wastewater treatment.

[0089] In some embodiments, the amount of the sulfonated carbon-modified waste carbon composite material added to the wastewater is 2.5-20 g / L.

[0090] In some embodiments, the application includes the following steps: adding the sulfonated carbon-modified waste carbon composite material to wastewater and treating it at 25-35 ℃ and a shaking speed of 180-240 rpm for 24-36 h.

[0091] In some embodiments, the ammonia nitrogen concentration in the wastewater is 50-500 mg / L, the DOC (soluble organic carbon) concentration is 200-1500 mg / L, and the total metal ion concentration is 10-1500 mg / L. The metal ions include, for example, Na+. + K + Mg 2 + Ca 2+ Cu 2+ and Cd 2+ One or more of the following.

[0092] This invention employs a one-step carbonization / sulfonation process to prepare sulfonated carbon, and then modifies the waste carbon using an alkaline activator followed by medium-temperature heat treatment. The sulfonated carbon and modified waste carbon are then combined with an adhesive to construct a sulfonated carbon-modified waste carbon composite material that possesses a well-developed porous structure, high specific surface area, and abundant chemical activity due to its rich functional groups. This invention fully utilizes the advantages of sulfonated carbon, which is rich in -SO3H, -COOH, and -OH groups, and the high specific surface area of ​​modified waste carbon. While transforming waste carbon into a valuable resource for resource utilization and regeneration, it effectively solves the problems of easy decomposition of functional groups and easy destruction of the carbon skeleton in traditional waste carbon regeneration processes, and transforms the defects of adsorption-saturated waste carbon into the advantages of a porous structure. The composite material of this invention retains the selectivity of sulfonated functional groups and other functional groups for cations, and significantly increases capacity through high specific surface area, thus overcoming the bottleneck of "easy decomposition of functional groups and easy destruction of the carbon skeleton" in traditional regeneration. This invention utilizes a dual-channel synergistic effect of "chemical adsorption and physical adsorption." At the same dosage, the composite material achieves an 80-180% increase in DOC removal rate compared to the original sulfonated carbon, a 15-40% increase in ammonia nitrogen removal rate, and a 10-50% increase in metal ion adsorption rate. The composite material of this invention is particularly suitable for treating high ammonia nitrogen (>200 mg / L) and high salinity (Na+) conditions. + This invention is suitable for pharmaceutical wastewater with complex pollutants, including those with concentrations >1000 mg / L and high DOC (>800 mg / L). Furthermore, the composite material of this invention, after adsorption saturation, can be converted back into modified carbon, achieving closed-loop recycling and realizing "one-time preparation, unlimited recycling." This invention has advantages such as simple operation, low cost, and low energy consumption, and has the potential to demonstrate outstanding pollutant reduction capabilities and green advantages in large-scale applications in wastewater treatment plants, achieving simultaneous optimization of environmental and economic benefits.

[0093] The technical solutions of the present invention are specifically illustrated below through embodiments, but the present invention is not limited to these embodiments. Of course, various modifications can be made within the scope of the key points of the present invention.

[0094] Test method:

[0095] Specific surface area and pore capacity: The N2 adsorption-desorption isotherms of the samples were tested using a McLeod multi-station physical adsorption instrument (ASPS2420, Tristar3020). The specific surface area was calculated by the BET method, and the pore capacity was determined by the total pore volume of single-point adsorption.

[0096] DOC determination: The concentration of DOC in the water sample was determined by combustion oxidation-nondispersive infrared absorption method using a TOC-L CPH / CPN TNM-LROHS analyzer manufactured by Shimadzu Corporation of Japan.

[0097] Ammonia nitrogen determination: The ammonia nitrogen content in the water sample was determined using a German DeChem-Tech fully automated water quality analyzer (Cleverchem 380) and the salicylic acid-hypochlorite spectrophotometric method (HJ 536-2009).

[0098] Determination of metal ion concentration: The concentration of metal elements in the water sample was determined by inductively coupled plasma optical emission spectrometry (ICP-OES, ICAP 7000 Series, Thermo Fisher Scientific, USA).

[0099] Example 1

[0100] This embodiment provides a sulfonated carbon-modified waste carbon composite material, the preparation method of which is as follows: Figure 1 As shown, it includes the following steps:

[0101] Step 1, Preparation of sulfonated carbon:

[0102] 250 g of 98% concentrated sulfuric acid was added to a 500 mL reaction vessel, and 40 g of rice husks were added. The mixture was heated to 180 °C using a microwave at 450 W / kg and stirred at 150 rpm for 4 h. After the reaction was completed, the mixture was cooled to room temperature and then washed with boiling deionized water (>80 °C). The mixture was then washed with boiling deionized water and anhydrous ethanol alternately until the pH of the filtrate was 7. The filter cake was then dried in an oven at 105 °C for 12 h and then ground to obtain 32 g of sulfonated carbon with a carbon yield of 80%.

[0103] The SEM image of the sulfonated carbon is as follows: Figure 2 As shown, the sulfonated carbon prepared from rice husks exhibits an irregular morphology with various small pores, indicating that gases such as SO2 and CO2 generated during the sulfuric acid carbonization / sulfonation process of rice husks cause the sulfonated carbon to ultimately form various pores. In this invention, the accelerating voltage for SEM testing was 5.00 kV, and Signal A = SE2.

[0104] The specific surface area of ​​this sulfonated carbon is 11.8 m². 2 / g, pore volume is 0.017 cm³ 3 / g.

[0105] Step 2, Modification of waste charcoal:

[0106] 30 g of waste carbon treated with wastewater was added to 200 mL of alkaline activator and soaked at room temperature for 1 h with occasional stirring during the soaking process. The alkaline activator was a mixed solution of ammonium nitrate, sodium hydroxide, and potassium hydroxide, with a mass fraction of 2.0% for sodium hydroxide, 2.0% for potassium hydroxide, and 5.0% for ammonium nitrate. After soaking, the mixture was filtered and dried. Then, it was placed in a tube furnace and heat-treated at 600 °C for 30 min under a nitrogen atmosphere with a flow rate of 100 mL / min and a heating rate of 15 °C / min, to obtain 22.5 g of modified waste carbon.

[0107] The waste carbon obtained after treating the wastewater is the waste carbon formed after treating the wastewater with the sulfonated carbon obtained in step 1. The specific steps include:

[0108] The sulfonated carbon obtained in step 1 (0 g, 0.75 g, 1.5 g, 3 g, and 6 g) was mixed with 300 mL of pharmaceutical wastewater and added to 500 mL flasks, for a total of 5 experiments. The mixture was placed in a shaker at 30 ℃ and 180 rpm for 24 h. After the reaction was complete, the mixture was filtered, and the filter cakes from the 5 experiments were mixed without washing. After drying, the waste carbon was obtained, and its SEM image is shown below. Figure 3 , Figure 4 and Figure 5 As shown, the pH of this pharmaceutical wastewater is 7.42, and the concentrations of pollutants are: 237.63 mg / L ammonia nitrogen, 867.6 mg / L DOC, and 1157.1 mg / L Na. + 7.1 mg / LK + 121.4 mg / L Mg 2+ 29.7 mg / L Ca 2+ 1.9 mg / L Cu 2+ 2.3 mg / L Cd 2+ .

[0109] The SEM image of the modified waste carbon is shown below. Figure 6 , Figure 7 and Figure 8 As shown, the waste carbon treated with alkaline activator and heat treatment exhibits significant changes in porosity compared to unmodified waste carbon. The pores are noticeably larger and denser, and more porous than before. Figure 2 The original sulfonated carbon in the sample is more uniform.

[0110] The specific surface area of ​​the modified waste char is 472.1 m².2 / g, with a pore volume of 0.19 cm³. 3 / g.

[0111] Step 3, Preparation of composite materials:

[0112] Take 10 g of sulfonated carbon obtained in step 1 and 5 g of modified waste carbon obtained in step 2, mix them in a beaker, and add a 5% (w / w) dilute nitric acid solution. Soak at room temperature for 30 min, then filter and remove the filter cake. Wash with water 5 times until the pH of the filtrate is 7. Dry the water-containing filter cake at 90 ℃ for 2 h. Then, add 14 g of the dried mixture to 14 mL of a 5% (w / w) carboxymethyl cellulose solution and stir evenly. After ultrasonic treatment for 20 min, let it stand for 4 h, filter, and wash with 60 mL of water 3 times to remove free carboxymethyl cellulose. Then dry at 60 ℃ for 12 h, and then grind evenly to obtain 14.3 g of sulfonated carbon-modified waste carbon composite material.

[0113] The SEM image of the sulfonated carbon-modified waste carbon composite material is shown below. Figure 9 and Figure 10 As shown, the composite material prepared in this embodiment has both the sheet-like structure of sulfonated carbon and the porous carbon structure that is bonded together, fully combining the characteristics of the sulfonated carbon obtained in step 1 and the porous characteristics of the modified waste carbon obtained in step 2.

[0114] The specific surface area of ​​this sulfonated carbon-modified waste carbon composite material is 168.3 m². 2 / g, pore volume is 0.075 cm³ / g. 3 Compared to the original sulfonated carbon, the composite material has a 14.3-fold increase in specific surface area and a 4.6-fold increase in pore capacity.

[0115] The application of the sulfonated carbon-modified waste carbon composite material in wastewater treatment in this embodiment is as follows:

[0116] Five groups of sulfonated carbon-modified waste carbon composite materials (0 g, 0.75 g, 1.5 g, 3 g, and 6 g) were mixed with 300 mL of pharmaceutical wastewater and added to 500 mL flasks. The mixtures were placed in shakers at 30 °C and 180 rpm for 24 hours. After the reaction, the mixtures were filtered to obtain the composite waste carbon and the treated wastewater. The composite waste carbon can be recycled back to step 2 as waste carbon, thus achieving resource utilization and regeneration.

[0117] As control group 1, 0 g, 0.75 g, 1.5 g, 3 g, and 6 g of sulfonated carbon obtained in step 1 were mixed with 300 mL of pharmaceutical wastewater and added to 500 mL flasks. A total of 5 groups of experiments were conducted. The mixtures were placed in a shaker and shaken at 30 ℃ and 180 rpm for 24 h. After the reaction was completed, the mixtures were filtered to obtain the treated wastewater.

[0118] As control group 2, 0 g, 0.75 g, 1.5 g, 3 g, and 6 g of the modified waste carbon obtained in step 2 were mixed with 300 mL of pharmaceutical wastewater and added to 500 mL flasks. A total of 5 groups of experiments were conducted. The mixtures were placed in a shaker and shaken at 30 ℃ and 180 rpm for 24 h. After the reaction was completed, the mixtures were filtered to obtain the treated wastewater.

[0119] The pharmaceutical wastewater had a pH of 7.42, and the concentrations of pollutants were: 237.63 mg / L ammonia nitrogen, 867.6 mg / L LDC, and 1157.1 mg / L Na. + 7.1 mg / LK + 121.4 mg / L Mg 2+ 29.7 mg / L Ca 2+ 1.9 mg / L Cu 2+ 2.3 mg / L Cd 2+ .

[0120] The concentrations of DOC and ammonia nitrogen in the treated wastewater were quantitatively analyzed using a TOC and water quality analyzer, and the concentrations of metal ions were analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES). Figure 11 The removal rate curves of soluble organic carbon (DOC) in wastewater are shown for the sulfonated carbon obtained in step 1, the modified waste carbon obtained in step 2, and the composite material obtained in step 3, under different addition amounts (0 g, 0.75 g, 1.5 g, 3 g, or 6 g). From... Figure 11 It can be seen that, compared with the original sulfonated carbon, the composite material in this embodiment improves the DOC removal rate by 85-135%, and the removal rates of DOC by the modified waste carbon and the composite material are similar. This is mainly attributed to the 14.3-fold increase in specific surface area of ​​the composite material (11.8 times). 168.3 m 2 The enhanced physical adsorption brought about by / g) and the synergistic effect of the functional group (-SO3H) of sulfonated carbon and the mesoporous structure of modified waste carbon.

[0121] Figure 12The graphs show the removal rates of ammonia nitrogen from wastewater by the sulfonated carbon obtained in step 1, the modified waste carbon obtained in step 2, and the composite material obtained in step 3, under different addition amounts (0 g, 0.75 g, 1.5 g, 3 g, or 6 g). From... Figure 12 It can be seen that the composite material in this embodiment improves the ammonia nitrogen removal rate by 17-37% compared to the original sulfonated carbon. However, the modified waste carbon, due to the lack of functional groups, only maintains an ammonia nitrogen removal rate of about 10%.

[0122] Table 1 shows the removal rates of different metal ions in wastewater by the sulfonated carbon obtained in step 1 of Example 1, the modified waste carbon obtained in step 2, and the composite material obtained in step 3, at an addition amount of 20 g / L.

[0123] Table 1

[0124]

[0125] As shown in Table 1, the composite material in this embodiment has a 16-36% higher adsorption rate for metal ions than the original sulfonated carbon. However, direct use of modified waste carbon carries the risk of metal "desorption" (such as Cd). 2+ The concentration rebounded from 2.30 mg / L to 2.55 mg / L, which may be related to the fact that it was not pickled and that the surface ash carried free metal ions.

[0126] Example 2

[0127] This embodiment provides a sulfonated carbon-modified waste carbon composite material, the preparation method of which includes the following steps:

[0128] Step 1, Preparation of sulfonated carbon:

[0129] 250 g of 98% concentrated sulfuric acid was added to a 500 mL reaction vessel, along with 60 g of straw. The mixture was heated to 180 °C using a microwave at 500 W / kg and stirred at 150 rpm for 4 h. After the reaction was complete, the mixture was cooled to room temperature and then washed with boiling deionized water (>80 °C). The mixture was then washed repeatedly with boiling deionized water and anhydrous ethanol until the pH of the filtrate was 7. The filter cake was then dried in an oven at 105 °C for 12 h and then ground to obtain 39.7 g of sulfonated carbon, with a carbon yield of 66.2%.

[0130] The specific surface area of ​​this sulfonated carbon is 6.10 m². 2 / g, pore volume is 0.01 cm³ 3 / g.

[0131] Step 2, Modification of waste charcoal:

[0132] 30 g of waste carbon treated with wastewater was added to 200 mL of alkaline activator and soaked at room temperature for 1.5 h with occasional stirring during the soaking process. The alkaline activator was a mixed solution of ammonium nitrate, sodium hydroxide, and potassium hydroxide, with a mass fraction of 1.0% for sodium hydroxide, 5.0% for potassium hydroxide, and 9.0% for ammonium nitrate. After soaking, the mixture was filtered and dried. Then, it was placed in a tube furnace and heat-treated at 700 °C for 20 min under a nitrogen atmosphere with a flow rate of 100 mL / min and a heating rate of 15 °C / min, to obtain 18.6 g of modified waste carbon.

[0133] The waste carbon obtained after treating the wastewater is the waste carbon formed after treating the wastewater with the sulfonated carbon obtained in step 1. The specific steps include:

[0134] 0 g, 0.75 g, 1.5 g, 3 g, and 6 g of the sulfonated carbon obtained in step 1 were mixed with 300 mL of pharmaceutical wastewater and added to 500 mL flasks, for a total of 5 experiments. The mixtures were placed in a shaker at 30 ℃ and 180 rpm for 24 h. After the reaction was completed, the mixture was filtered, and the filter cakes from the 5 experiments were mixed without washing and dried to obtain waste carbon. The pH of the pharmaceutical wastewater was 7.42, and the concentrations of pollutants were: 237.63 mg / L ammonia nitrogen, 867.6 mg / L DOC, and 1157.1 mg / L Na. + 7.1 mg / LK + 121.4 mg / L Mg 2+ 29.7 mg / L Ca 2+ 1.9 mg / L Cu 2+ 2.3 mg / L Cd 2+ .

[0135] The specific surface area of ​​the modified waste char is 437.6 m². 2 / g, pore volume is 0.15 cm³ 3 / g.

[0136] Step 3, Preparation of composite materials:

[0137] Take 15g of sulfonated carbon obtained in step 1 and 5g of modified waste carbon obtained in step 2, mix them in a beaker, and add a 5% (w / w) dilute nitric acid solution. Soak at room temperature for 20 min, then filter and remove the filter cake. Wash with water 6 times until the pH of the filtrate is 7. Dry the water-containing filter cake at 90 ℃ for 2 h. Then, add 19.6g of the dried mixture to 20 mL of a 4% (w / w) carboxymethyl cellulose solution and stir evenly. After ultrasonic treatment for 20 min, let it stand for 2.5 h, filter, and wash with 60 mL of water 3 times to remove free carboxymethyl cellulose. Then dry at 60 ℃ for 12 h, and then grind evenly to obtain 20.2g of sulfonated carbon-modified waste carbon composite material.

[0138] The specific surface area of ​​this sulfonated carbon-modified waste carbon composite material is 116.1 m². 2 / g, with a pore volume of 0.047 cm³. 3 / g, compared to the original sulfonated carbon, the specific surface area of ​​this composite material is increased by 19 times and the pore capacity is increased by 4.7 times.

[0139] The application of the sulfonated carbon-modified waste carbon composite material in wastewater treatment in this embodiment is as follows:

[0140] Five groups of sulfonated carbon-modified waste carbon composite materials (0 g, 0.75 g, 1.5 g, 3 g, and 6 g) were mixed with 300 mL of pharmaceutical wastewater and added to 500 mL flasks. The mixtures were placed in shakers at 30 °C and 180 rpm for 24 hours. After the reaction, the mixtures were filtered to obtain the composite waste carbon and the treated wastewater. The composite waste carbon can be recycled back to step 2 as waste carbon, thus achieving resource utilization and regeneration.

[0141] As control group 1, 0 g, 0.75 g, 1.5 g, 3 g, and 6 g of sulfonated carbon obtained in step 1 were mixed with 300 mL of pharmaceutical wastewater and added to 500 mL flasks. A total of 5 groups of experiments were conducted. The mixtures were placed in a shaker and shaken at 30 ℃ and 180 rpm for 24 h. After the reaction was completed, the mixtures were filtered to obtain the treated wastewater.

[0142] As control group 2, 0 g, 0.75 g, 1.5 g, 3 g, and 6 g of the modified waste carbon obtained in step 2 were mixed with 300 mL of pharmaceutical wastewater and added to 500 mL flasks. A total of 5 groups of experiments were conducted. The mixtures were placed in a shaker and shaken at 30 ℃ and 180 rpm for 24 h. After the reaction was completed, the mixtures were filtered to obtain the treated wastewater.

[0143] The pharmaceutical wastewater had a pH of 7.42, and the concentrations of pollutants were: 237.63 mg / L ammonia nitrogen, 867.6 mg / L LDC, and 1157.1 mg / L Na. + 7.1 mg / LK + 121.4 mg / L Mg 2+ 29.7 mg / L Ca 2+ 1.9 mg / L Cu 2+ 2.3 mg / L Cd 2+ .

[0144] The concentrations of DOC and ammonia nitrogen in the treated wastewater were quantitatively analyzed using a TOC and water quality analyzer. The concentrations of metal ions were analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES). The sulfonated carbon obtained in step 1, the modified waste carbon obtained in step 2, and the composite material obtained in step 3 were added at a dosage of 20 g / L to the wastewater.

[0145] The DOC removal rates were 22.7% (sulfonated carbon), 72.7% (modified waste carbon), and 62.5% (composite material). Compared with sulfonated carbon, the composite material improved the DOC removal rate by [(62.5-22.7) / 22.7]×100%=175.3%.

[0146] The ammonia nitrogen removal rates were 72.7% (sulfonated carbon), 9.6% (modified waste carbon), and 89.4% (composite material), respectively. The composite material improved the ammonia nitrogen removal rate by 23.0% compared with sulfonated carbon.

[0147] Take Na + For example, for Na + The removal rates were 25.2% (sulfonated carbon), -18.7% (modified waste carbon), and 37.6% (composite materials), respectively. Compared to sulfonated carbon, the composite materials showed better removal of Na. + The removal rate increased by 49.2%.

[0148] Example 3

[0149] This embodiment provides a sulfonated carbon-modified waste carbon composite material, the preparation method of which includes the following steps:

[0150] Step 1, Preparation of sulfonated carbon:

[0151] 250 g of 98% concentrated sulfuric acid was added to a 500 mL reaction vessel, along with 50 g of sucrose. The mixture was heated to 180 °C using a microwave at 500 W / kg and stirred at 150 rpm for 4 h. After the reaction was complete, the mixture was cooled to room temperature and then washed with boiling deionized water (>80 °C). The mixture was then washed repeatedly with boiling deionized water and anhydrous ethanol until the pH of the filtrate was 7. The filter cake was then dried in an oven at 105 °C for 12 h and then ground to obtain 36.7 g of sulfonated carbon, with a carbon yield of 73.4%.

[0152] The specific surface area of ​​this sulfonated carbon is 9.25 m². 2 / g, pore volume is 0.011 cm³ 3 / g.

[0153] Step 2, Modification of waste charcoal:

[0154] 30 g of waste carbon treated with wastewater was added to 200 mL of alkaline activator and soaked at room temperature for 2 h with occasional stirring during the soaking process. The alkaline activator was a mixed solution of ammonium nitrate, sodium hydroxide, and potassium hydroxide, with a mass fraction of 3% sodium hydroxide, 1.0% potassium hydroxide, and 7.0% ammonium nitrate. After soaking, the mixture was filtered and dried. Then, it was placed in a tube furnace and heat-treated at 500 °C for 30 min under a nitrogen atmosphere with a flow rate of 100 mL / min and a heating rate of 15 °C / min, to obtain 24.7 g of modified waste carbon.

[0155] The waste carbon obtained after treating the wastewater is the waste carbon formed after treating the wastewater with the sulfonated carbon obtained in step 1. The specific steps include:

[0156] 0 g, 0.75 g, 1.5 g, 3 g, and 6 g of the sulfonated carbon obtained in step 1 were mixed with 300 mL of pharmaceutical wastewater and added to 500 mL flasks, for a total of 5 experiments. The mixtures were placed in a shaker at 30 ℃ and 180 rpm for 24 h. After the reaction was completed, the mixture was filtered, and the filter cakes from the 5 experiments were mixed without washing and dried to obtain waste carbon. The pH of the pharmaceutical wastewater was 7.42, and the concentrations of pollutants were: 237.63 mg / L ammonia nitrogen, 867.6 mg / L DOC, and 1157.1 mg / L Na. + 7.1 mg / LK + 121.4 mg / L Mg 2+ 29.7 mg / L Ca 2+ 1.9 mg / L Cu 2+ 2.3 mg / L Cd 2+ .

[0157] The specific surface area of ​​the modified waste carbon is 312.1 m². 2 / g, pore volume is 0.13 cm³ 3 / g.

[0158] Step 3, Preparation of composite materials:

[0159] Take 8 g of sulfonated carbon obtained in step 1 and 8 g of modified waste carbon obtained in step 2, mix them in a beaker, and add a 5% (w / w) dilute nitric acid solution. Soak at room temperature for 30 min, then filter and remove the filter cake. Wash with water 6 times until the pH of the filtrate is 7. Dry the water-containing filter cake at 90 ℃ for 2 h. Then, add 15 g of the dried mixture to 20 mL of a 3% (w / w) carboxymethyl cellulose solution and stir evenly. After ultrasonic treatment for 20 min, let it stand for 2.5 h, filter, and wash with 60 mL of water 3 times to remove free carboxymethyl cellulose. Then dry at 60 ℃ for 12 h, and then grind evenly to obtain 15.12 g of sulfonated carbon-modified waste carbon composite material.

[0160] The specific surface area of ​​this sulfonated carbon-modified waste carbon composite material is 106.3 m². 2 / g, with a pore volume of 0.047 cm³. 3 / g, compared to the original sulfonated carbon, the specific surface area of ​​this composite material is increased by 17.7 times and the pore capacity is increased by 6.7 times.

[0161] The application of the sulfonated carbon-modified waste carbon composite material in wastewater treatment in this embodiment is as follows:

[0162] Five groups of sulfonated carbon-modified waste carbon composite materials (0 g, 0.75 g, 1.5 g, 3 g, and 6 g) were mixed with 300 mL of pharmaceutical wastewater and added to 500 mL flasks. The mixtures were placed in shakers at 30 °C and 180 rpm for 24 hours. After the reaction, the mixtures were filtered to obtain the composite waste carbon and the treated wastewater. The composite waste carbon can be recycled back to step 2 as waste carbon, thus achieving resource utilization and regeneration.

[0163] As control group 1, 0 g, 0.75 g, 1.5 g, 3 g, and 6 g of sulfonated carbon obtained in step 1 were mixed with 300 mL of pharmaceutical wastewater and added to 500 mL flasks. A total of 5 groups of experiments were conducted. The mixtures were placed in a shaker and shaken at 30 ℃ and 180 rpm for 24 h. After the reaction was completed, the mixtures were filtered to obtain the treated wastewater.

[0164] As control group 2, 0 g, 0.75 g, 1.5 g, 3 g, and 6 g of the modified waste carbon obtained in step 2 were mixed with 300 mL of pharmaceutical wastewater and added to 500 mL flasks. A total of 5 groups of experiments were conducted. The mixtures were placed in a shaker and shaken at 30 ℃ and 180 rpm for 24 h. After the reaction was completed, the mixtures were filtered to obtain the treated wastewater.

[0165] The pharmaceutical wastewater had a pH of 7.42, and the concentrations of pollutants were: 237.63 mg / L ammonia nitrogen, 867.6 mg / L LDC, and 1157.1 mg / L Na. + 7.1 mg / LK + 121.4 mg / L Mg 2+ 29.7 mg / L Ca 2+ 1.9 mg / L Cu 2+ 2.3 mg / L Cd 2+ .

[0166] The concentrations of DOC and ammonia nitrogen in the treated wastewater were quantitatively analyzed using a TOC and water quality analyzer. The concentrations of metal ions were analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES). The sulfonated carbon obtained in step 1, the modified waste carbon obtained in step 2, and the composite material obtained in step 3 were added at a dosage of 20 g / L to the wastewater.

[0167] The DOC removal rates were 28.3% (sulfonated carbon), 70.5% (modified waste carbon), and 60.7% (composite material). Compared with sulfonated carbon, the composite material improved the DOC removal rate by [(60.7-28.3) / 28.3]×100%=114.5%.

[0168] The ammonia nitrogen removal rates were 72.7% (sulfonated carbon), 11.2% (modified waste carbon), and 66.8% (composite material), respectively. The ammonia nitrogen removal rate of the composite material was 8.1% lower than that of sulfonated carbon.

[0169] Take Na + For example, for Na + The removal rates were 24.8% (sulfonated carbon), -20.4% (modified waste carbon), and 21.3% (composite materials), respectively. Compared to sulfonated carbon, the composite materials showed better removal of Na... + The removal rate decreased by 14.1%.

[0170] Example 3 illustrates that a decrease in the proportion of sulfonated carbon in the composite material affects the removal efficiency of cationic pollutants.

[0171] Comparative Example 1

[0172] Step 1, Preparation of sulfonated carbon:

[0173] 250 g of 98% concentrated sulfuric acid was added to a 500 mL reaction vessel, and 40 g of rice husks were added. The mixture was heated to 180 °C using a microwave at 450 W / kg and stirred at 150 rpm for 4 h. After the reaction was completed, the mixture was cooled to room temperature and then washed with boiling deionized water (>80 °C). The mixture was then washed with boiling deionized water and anhydrous ethanol alternately until the pH of the filtrate was 7. The filter cake was then dried in an oven at 105 °C for 12 h and then ground to obtain 32 g of sulfonated carbon with a carbon yield of 80%.

[0174] The specific surface area of ​​this sulfonated carbon is 11.8 m². 2 / g, pore volume is 0.017 cm³ 3 / g.

[0175] Step 2, direct pyrolysis modification of sulfonated carbon:

[0176] Four portions (7 g each) of the sulfonated char obtained in step 1 were placed in a tube furnace and subjected to constant-temperature heat treatment at 400 °C, 500 °C, 600 °C, and 700 °C for 30 min under a nitrogen atmosphere at a flow rate of 100 mL / min and a heating rate of 15 °C / min. The modified sulfonated char obtained after pyrolysis were 5.17 g (400 °C), 4.61 g (500 °C), 4.35 g (600 °C), and 4.21 g (700 °C), respectively. The char yields were 73.9% (400 °C), 65.9% (500 °C), 62.2% (600 °C), and 60.1% (700 °C), respectively.

[0177] The specific surface area of ​​this modified sulfonated carbon is 184.97 m² from 400 °C to 700 °C. 2 / g, 275.96 m 2 / g, 386.09 m 2 / g, 322.60 m 2 / g, with pore capacities of 0.11 cm³. 3 / g, 0.14 cm 3 / g, 0.18 cm 3 / g, 0.16cm 3 / g.

[0178] SEM images of the modified sulfonated carbon obtained by direct pyrolysis of sulfonated carbon at different temperatures are shown below. Figure 13 , Figure 14 , Figure 15 and Figure 16 As shown, it can be seen that as the temperature increases, the pore structure of carbon materials increases. When the temperature exceeds 600 ℃, the pores of modified carbon collapse, and the specific surface area and pore capacity decrease.

[0179] The application of the modified sulfonated carbon in wastewater treatment in this comparative example is as follows:

[0180] 2 g of modified sulfonated carbon prepared at 400℃-700℃ was mixed with 100 mL of pharmaceutical wastewater and added to a 500 mL flask. Four sets of experiments were conducted. The mixture was placed in a shaker and shaken at 30℃ and 180 rpm for 24 h. After the reaction was completed, the wastewater was filtered to obtain the treated wastewater.

[0181] As a control group, 2 g of sulfonated carbon obtained in step 1 was mixed with 100 mL of pharmaceutical wastewater and added to a 500 mL flask. Three parallel experiments were conducted. The mixture was placed in a shaker and shaken at 30 °C and 180 rpm for 24 h. After the reaction was completed, the wastewater was filtered to obtain the treated wastewater.

[0182] The pharmaceutical wastewater had a pH of 7.42, and the concentrations of pollutants were: 237.63 mg / L ammonia nitrogen, 867.6 mg / L LDC, and 1157.1 mg / L Na. + 7.1 mg / LK + 121.4 mg / L Mg 2+ 29.7 mg / L Ca 2+ 1.9 mg / L Cu 2+ 2.3 mg / L Cd 2+ .

[0183] The concentrations of DOC and ammonia nitrogen in the treated wastewater were quantitatively analyzed using a TOC and water quality analyzer. The concentrations of metal ions were analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES). The sulfonated carbon obtained in step 1 and the modified sulfonated carbon obtained in step 2, at an addition dosage of 20 g / L, had the following effects on the wastewater:

[0184] The DOC removal rates were 32.3% (sulfonated carbon), 61.5% (400 ℃), 67.8% (500 ℃), 70.2% (600 ℃), and 63.6% (700 ℃). At 700 ℃, the pores of the modified sulfonated carbon collapsed, and the micropore walls approached and merged, causing the originally small micropores to gradually enlarge or even disappear, thus reducing the number of micropores and the specific surface area, resulting in a decrease in its adsorption capacity for pollutants.

[0185] The ammonia nitrogen removal rates were 75.1% (sulfonated carbon), 27.5% (400 ℃), 14.0% (500 ℃), 10.4% (600 ℃) and 8.3% (700 ℃), respectively.

[0186] Take Na + For example, for Na+ The removal rates were 21.4% (sulfonated carbon), 10.3% (400 ℃), 8.2% (500 ℃), 3.2% (600 ℃) and 1.6% (700 ℃), respectively.

[0187] As the pyrolysis temperature increases, a large number of active groups on the surface of sulfonated carbon decompose, resulting in a significant decrease in its adsorption capacity for cationic pollutants (ammonia nitrogen and metal ions).

[0188] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a sulfonated carbon-modified waste carbon composite material, comprising the following steps: Step 1, Preparation of sulfonated carbon: A solution of sulfonating agent is mixed with a carbon-containing raw material and then heated to react, yielding sulfonated carbon. Step 2, Modification of waste charcoal: The waste carbon after wastewater treatment is first treated with an alkaline activator and then subjected to heat treatment to obtain modified waste carbon. Step 3, Preparation of composite materials: The sulfonated carbon obtained in step 1 and the modified waste carbon obtained in step 2 are mixed, soaked in an acid solution, and then mixed with a binder to obtain the sulfonated carbon-modified waste carbon composite material.

2. The method for preparing the sulfonated carbon-modified waste carbon composite material according to claim 1, wherein, In step 1, the heating reaction is carried out at a temperature of 160-250 °C for 4-24 h. And / or, in step 1, the carbon-containing raw material includes agricultural waste biomass and / or carbohydrates; And / or, in step 1, the sulfonating agent in the solution of the sulfonating agent includes one or more of sulfuric acid, toluenesulfonic acid, sulfosalicylic acid and chlorosulfonic acid; And / or, in step 1, the mass ratio of the sulfonating agent to the carbon-containing raw material in the sulfonating agent solution is (4-20):1; And / or, in step 1, the specific surface area of ​​the sulfonated carbon is 6-14 m². 2 / g, pore volume is 0.01-0.025 cm³ / g. 3 / g.

3. The method for preparing the sulfonated carbon-modified waste carbon composite material according to claim 2, wherein, In step 1, the agricultural waste biomass includes one or more of rice husks, straw, and fruit peels; the carbohydrates include one or more of glucose, fructose, xylose, sucrose, and cellulose.

4. The method for preparing the sulfonated carbon-modified waste carbon composite material according to claim 1, wherein, In step 2, the waste carbon after treating the wastewater includes waste carbon formed by treating the wastewater with the sulfonated carbon obtained in step 1, and / or waste carbon formed by treating the wastewater with the sulfonated carbon-modified waste carbon composite material obtained in step 3. And / or, in step 2, the alkaline activator treatment includes: soaking the waste carbon in an alkaline solution for 1-4 hours; And / or, in step 2, the heat treatment temperature is 400-800 °C and the time is 15-30 min; And / or, in step 2, the heat treatment is carried out in a protective gas atmosphere at a flow rate of 100-200 mL / min; And / or, in step 2, the specific surface area of ​​the modified waste carbon is 180-500 m². 2 / g, pore volume is 0.1-0.2cm³ 3 / g.

5. The method for preparing the sulfonated carbon-modified waste carbon composite material according to claim 4, wherein, In step 2, the alkaline solution comprises a mixed solution of ammonium nitrate, sodium hydroxide, and potassium hydroxide; in the mixed solution, the mass fraction of ammonium nitrate is 5.0-15.0%, the mass fraction of sodium hydroxide is 1.0-5.0%, and the mass fraction of potassium hydroxide is 1.0-7.0%. And / or, in step 2, the ratio of the waste carbon to the alkaline solution is (50-200) g: 1 L.

6. The method for preparing the sulfonated carbon-modified waste carbon composite material according to claim 1, wherein, In step 3, the mass ratio of the sulfonated carbon to the modified waste carbon is (1-5):1; And / or, in step 3, the acid solution includes a dilute nitric acid solution; And / or, in step 3, the mass concentration of the acid solution is 1-5%; And / or, in step 3, the immersion time in the acid solution is 10-30 min; And / or, in step 3, mixing with the adhesive includes: adding the product soaked in the acid solution to the adhesive solution, sonicating for 15-30 min, and then letting it stand for 2-6 h.

7. The method for preparing the sulfonated carbon-modified waste carbon composite material according to claim 6, wherein, In step 3, the mass ratio of the product soaked in the acid solution to the adhesive in the adhesive solution is (20-50):1; And / or, in step 3, the adhesive in the adhesive solution includes carboxymethyl cellulose; And / or, in step 3, the mass concentration of the adhesive solution is 2-5%.

8. A sulfonated carbon-modified waste carbon composite material, which is prepared by the method for preparing the sulfonated carbon-modified waste carbon composite material according to any one of claims 1-7; the specific surface area of ​​the sulfonated carbon-modified waste carbon composite material is 50-220 m². 2 / g, with a pore volume of 0.025-0.13 cm³. 3 / g.

9. The application of the sulfonated carbon-modified waste carbon composite material according to claim 8 in wastewater treatment.

10. The application according to claim 9, wherein, The amount of the sulfonated carbon-modified waste carbon composite material added to the wastewater is 2.5-20 g / L; And / or, the application includes the following steps: adding the sulfonated carbon-modified waste carbon composite material to wastewater and treating it at 25-35 ℃ and a shaking speed of 180-240 rpm for 24-36 h; And / or, the ammonia nitrogen concentration in the wastewater is 50-500 mg / L, the DOC concentration is 200-1500 mg / L, and the total metal ion concentration is 10-1500 mg / L.

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