Porous carbon with photo-thermal performance and preparation method and application thereof
The porous carbon material prepared by low-temperature carbonization, combined with photothermal properties and persulfate activation technology, solves the problems of high energy consumption and insufficient catalytic activity in the preparation of porous biochar, and achieves efficient degradation of tetracycline, which has broad application prospects.
Patent Information
- Application Number
- CN202511090048.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-05
- Publication Date
- 2025-12-02
AI Technical Summary
Existing methods for preparing porous biochar are energy-intensive, pose significant safety risks, and have limited catalytic activity, making it difficult to efficiently activate persulfate to degrade tetracycline. Traditional water treatment technologies also have limited removal efficiency for tetracycline.
A low-temperature carbonization technique was employed, using a mixed salt of NaCl and KCl as a template. Porous carbon was prepared by low-temperature pyrolysis of sodium lignin sulfonate. Combined with photothermal properties, persulfate was activated to degrade tetracycline, reducing energy consumption and improving catalytic performance.
A low-cost, safe, and metal-free porous carbon material has been developed, which can efficiently activate persulfate under photothermal conditions, significantly improve the degradation efficiency of tetracycline, and reduce energy consumption and safety risks.
Smart Images
Figure CN121044565A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of antibiotic wastewater treatment technology, specifically a porous carbon with photothermal properties, its preparation method, and its application. Background Technology
[0002] In recent years, the problem of antibiotic residues in the environment has become increasingly serious, posing a potential threat to ecosystems and human health. Among them, tetracycline antibiotics, as a class of broad-spectrum antibiotics, are widely used in medical treatment, animal husbandry, and aquaculture. Due to incomplete metabolism and strong persistence, tetracycline enters the water and soil environment through wastewater discharge, agricultural runoff, and other pathways, and even accumulates in aquatic organisms, exacerbating the risk of antibiotic resistance gene transmission. However, traditional water treatment technologies (such as biodegradation, adsorption, and conventional oxidation methods) have limited removal efficiency for tetracycline. Therefore, developing efficient and green tetracycline degradation technologies has become an important issue in environmental governance.
[0003] Persulfate has become an effective means of degrading antibiotic pollutants due to its strong oxidizing power, wide pH range and long half-life. However, persulfate usually requires a certain amount of energy or additional electrons to be activated, thereby generating highly oxidizing sulfate radicals (SO4·-) and hydroxyl radicals (·OH), which can achieve efficient degradation of antibiotic pollutants.
[0004] Porous biochar materials possess advantages such as large specific surface area, abundant surface functional groups, wide availability, and environmental friendliness, making them an ideal persulfate activation catalyst. However, existing methods for preparing biochar typically rely on high-temperature pyrolysis (>500℃), which is not only energy-intensive but also poses safety hazards, limiting its large-scale application. Furthermore, the catalytic activity of raw porous biochar is limited, usually requiring chemical modification, such as non-metallic doping and metal loading, to improve its electron transfer capacity and persulfate activation performance, further increasing preparation costs and process complexity.
[0005] Therefore, developing a low-temperature, low-energy-consumption, safe and controllable porous biochar preparation technology, and optimizing its performance in activating persulfate to degrade tetracycline, has important scientific significance and application value. Summary of the Invention
[0006] The purpose of this invention is to provide a porous carbon with photothermal properties, its preparation method, and its application. It not only has the advantages of low temperature, low energy consumption, and green environmental protection, but also the prepared porous carbon has excellent photothermal properties, which can fully activate persulfate and thus efficiently degrade tetracycline.
[0007] This invention is achieved through the following technical solution:
[0008] A method for preparing porous carbon with photothermal properties includes the following steps:
[0009] Step 1: Mix NaCl and KCl in a mass ratio of 1:1 to obtain a mixed salt;
[0010] Step 2: Mix sodium lignosulfonate and mixed salt evenly according to a mass ratio of 1:(3-5), spread the mixture in a ceramic boat, place the ceramic boat in a muffle furnace, and heat it from room temperature to 300-500℃ at a heating rate of 3-5℃ / min under a N2 atmosphere. Hold the temperature for 5-7 hours, and then cool it to room temperature with the furnace to obtain a black reactant.
[0011] Step 3: Under ultrasonic assistance, the black reactant is washed several times and dried to obtain porous carbon.
[0012] Furthermore, the cleaning in step 3 involves washing three times each with a 1 mol / L HCl solution and pure water.
[0013] Furthermore, the drying in step 3 is carried out at 80–100°C for 12 hours.
[0014] A porous carbon with photothermal properties.
[0015] An application of porous carbon with photothermal properties includes the following steps: adding porous carbon to tetracycline wastewater, stirring under dark conditions to allow tetracycline to be fully adsorbed by the porous carbon, then adding persulfate to the tetracycline wastewater, and stirring under simulated sunlight to degrade the tetracycline pollutant in the wastewater.
[0016] Furthermore, the concentration of tetracycline in the tetracycline wastewater is 20–30 mg / L, the ratio of porous carbon to tetracycline wastewater is (0.1–0.14 g): 1 L, and the ratio of persulfate to tetracycline wastewater is (0.5–0.7 g): 1 L.
[0017] Furthermore, both the initial stirring and the subsequent stirring are performed at a speed of 400–600 r / min for 1 hour.
[0018] Furthermore, the simulated solar light source is a xenon lamp with an operating current of 15-20A.
[0019] The present invention has the following beneficial technical effects:
[0020] First, using low-cost and widely available sodium lignosulfonate as a carbon source, porous carbon with abundant pores and surface functional groups can be directly obtained through low-temperature carbonization without additional chemical modification, reducing production costs and simplifying the process. Second, the NaCl and KCl mixed salt template can promote pore formation during pyrolysis, helping to increase the specific surface area of porous carbon and enhance adsorption and catalytic performance. Compared with corrosive reagents such as strong acids / bases, it is safer and lower in cost. Third, the NaCl and KCl mixed in a certain proportion form a eutectic, whose melting point can be reduced to about 500℃ or even lower. This allows the mixed salt to form a liquid molten salt environment at relatively low temperatures. The liquid NaCl and KCl mixed molten salt can penetrate into the biomass, increasing the contact between the biomass and the molten salt. The increased contact area allows for rapid and uniform heat transfer, causing biomass to swell, disrupting its original structure, and lowering the activation energy of the pyrolysis reaction. This facilitates the low-temperature preparation of biochar, allowing for carbonization of sodium lignosulfonate at temperatures of 300–500°C. This significantly reduces energy consumption and safety hazards. Furthermore, the molten NaCl and KCl salts can be recycled and reused, reducing resource waste and environmental pollution, which aligns better with green chemistry principles. Finally, the prepared porous carbon accelerates the activation of persulfate (PDS), promoting the generation of SO4·- and ·OH free radicals, thereby effectively degrading tetracycline. Especially under light conditions, the excellent photothermal conversion capacity of porous carbon accelerates local heating, synergistically activating PDS and further improving the degradation efficiency of tetracycline. In summary, this invention prepares porous carbon with excellent photothermal properties, low cost, and green efficiency through one-step low-temperature carbonization of mixed salt templates and precursors. Combining photothermal effect with persulfate activation technology, it achieves efficient degradation of tetracycline in wastewater. It features low energy consumption, high safety, no metal pollution, and excellent degradation efficiency, and has broad application prospects in the field of antibiotic wastewater treatment.
[0021] By rationally controlling the addition of porous carbon and persulfate (PDS) in tetracycline wastewater, and with the aid of light, tetracycline can be fully degraded, reducing the risk of secondary pollution. Compared with traditional homogeneous catalysis (such as transition metal ion-activated PDS), the heterogeneous photothermal catalytic system of this invention is more stable, has no metal leaching problem, and is more suitable for actual wastewater treatment. Attached Figure Description
[0022] Figure 1 SEM images and elemental distribution mapping diagrams of porous carbon prepared in Example 3 of the present invention at different magnifications;
[0023] Figure 2 The XRD patterns of the porous carbon prepared in Examples 1 to 3 of this invention;
[0024] Figure 3The performance curve of porous carbon prepared in Example 3 of the present invention for degrading tetracycline by activated persulfate (PDS) under no light irradiation;
[0025] Figure 4 The UV-Vis absorption spectrum of the porous carbon prepared in Example 3 of this invention;
[0026] Figure 5 The curve showing the effect of light on water temperature on the porous carbon prepared in Example 3 of this invention;
[0027] Figure 6(a) shows the performance curves of the porous carbon prepared in Example 3 of the present invention in the degradation of tetracycline by persulfate (PDS) under darkness and light.
[0028] Figure 6(b) shows the first-order reaction rate constant curve corresponding to Figure 6(a). Detailed Implementation
[0029] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.
[0030] In Application Examples 1 to 4 of this invention, the absorbance of the tetracycline degradation solution was measured at 357 nm using a UV-Vis spectrophotometer. The formula for calculating the tetracycline removal rate η is expressed as follows:
[0031]
[0032] In the formula, C0 represents the initial concentration of the tetracycline solution, C represents the concentration of the tetracycline degradation solution at any time, A0 represents the initial absorbance, and A represents the absorbance at any time t.
[0033] In Application Examples 2 to 4 of this invention, a xenon lamp with an operating current of 15 to 20 A and a rated power of 300 W is used as a simulated solar light source.
[0034] Example 1
[0035] Step 1: Mix NaCl and KCl in a mass ratio of 1:1 to obtain a mixed salt;
[0036] Step 2: Mix 0.5g sodium lignosulfonate and 1.5g mixed salt evenly according to a mass ratio of 1:3, spread the mixture in a porcelain boat, place the boat in a muffle furnace, and heat it from room temperature to 300℃ at a heating rate of 3℃ / min under a N2 atmosphere. Hold the temperature for 5 hours, and then cool it to room temperature with the furnace to obtain a black reactant.
[0037] Step 3: Under ultrasonic assistance, the black reactant was washed three times each with a 1 mol / L HCl solution and pure water. After drying at 80°C for 12 hours, porous carbon was obtained, denoted as SL-300.
[0038] Example 2
[0039] Step 1: Mix NaCl and KCl in a mass ratio of 1:1 to obtain a mixed salt;
[0040] Step 2: Mix 1g of sodium lignosulfonate and 4g of mixed salt evenly according to a mass ratio of 1:4, spread the mixture in a porcelain boat, place the boat in a muffle furnace, and heat it from room temperature to 400℃ at a heating rate of 4℃ / min under a N2 atmosphere. Hold the temperature for 6 hours, and then cool it to room temperature with the furnace to obtain a black reactant.
[0041] Step 3: Under ultrasonic assistance, the black reactant was washed three times each with a 1 mol / L HCl solution and pure water. After drying at 90°C for 12 hours, porous carbon was obtained, denoted as SL-400.
[0042] Example 3
[0043] Step 1: Mix NaCl and KCl in a mass ratio of 1:1 to obtain a mixed salt;
[0044] Step 2: Mix 1.5g sodium lignosulfonate and 7.5g mixed salt evenly according to a mass ratio of 1:5, spread the mixture in a ceramic boat, place the ceramic boat in a muffle furnace, and heat it from room temperature to 500℃ at a heating rate of 5℃ / min under a N2 atmosphere. Hold the temperature for 7 hours, and then cool it to room temperature with the furnace to obtain a black reactant.
[0045] Step 3: Under ultrasonic assistance, the black reactant was washed three times each with a 1 mol / L HCl solution and pure water. It was then dried at 100℃ for 12 hours to obtain porous carbon, denoted as SL-500.
[0046] from Figure 1 As can be seen from (a) and (b), the porous carbon surface prepared in Example 3 has a rich porous structure, which can provide more active sites, thereby promoting the adsorption and degradation of tetracycline; from Figure 1 (c) It can be seen that the porous carbon prepared in Example 3 is composed of three elements: C, O and S, and the three elements are evenly distributed, which can form a variety of active groups, thereby promoting the adsorption and activation of persulfate.
[0047] from Figure 2 It can be seen that two relatively broad diffraction peaks of graphite-like carbon appeared at 25.9° and 42.5°, corresponding to the (002) and (100) characteristic crystal planes respectively. There were no other impurity peaks, indicating that graphite-like porous carbon materials were successfully prepared in Examples 1 to 3.
[0048] from Figure 4It can be seen that the porous carbon prepared in Example 3 has significant light absorption capacity throughout the entire ultraviolet-visible region.
[0049] The porous carbon prepared in Example 3 was added to pure water, and the change in water temperature over time was observed. Pure water without the addition of porous carbon was used as a control group. The results are as follows: Figure 5 As shown, when the porous carbon prepared in Example 3 is added to water, the water temperature gradually increases with the extension of light exposure time, reaching 60°C after 30 minutes, and then tends to reach equilibrium. Under the same conditions, when pure water without added porous carbon is exposed to light, the water temperature can reach a maximum of 45°C within 1 hour. This indicates that the porous carbon prepared in Example 3 has a strong photothermal effect and can fully absorb light to generate local heat, thus raising the water temperature.
[0050] Application Example 1
[0051] 10 mg of the porous carbon prepared in Examples 1-3 was added to 100 mL of a 20 mg / L tetracycline solution. The solution was stirred at 400 rpm for 1 h in the dark to reach adsorption equilibrium. Then, 50 mg of persulfate was added, and the mixture was stirred at 400 rpm for another 1 h in the dark to degrade the tetracycline. During this process, 3 mL of the tetracycline degradation solution was taken every 10 min to test the absorbance and calculate the tetracycline removal rate. The results are shown in [reference needed]. Figure 3 .
[0052] from Figure 3 It can be seen that the porous carbon prepared in Examples 1 to 3 can also activate persulfate (PDS) to degrade tetracycline in the absence of light. As the pyrolysis temperature increases from 300℃ to 500℃, the performance of porous carbon in activating persulfate to degrade tetracycline gradually increases. This is because the porous carbon pyrolyzed at 300℃ is mainly amorphous carbon with incomplete aromatic structure and poor conductivity. As the pyrolysis temperature increases, the carbon elements in sodium lignin sulfonate gradually recombine into a more ordered graphitic aromatic structure, which is conducive to the transfer of electrons between biochar, persulfate and tetracycline, and promotes the activation of persulfate. Therefore, the tetracycline degradation efficiency corresponding to the porous carbon prepared in Example 3 reached 83.0%.
[0053] Application Example 2
[0054] Take 10 mg of the porous carbon prepared in Examples 1 to 3 respectively, and add it to 100 mL of tetracycline solution with a concentration of 20 mg / L. Under dark conditions, stir at 400 r / min for 1 h to reach adsorption equilibrium. Then add 50 mg of persulfate. Use a 300 W xenon lamp with a Cut 420 nm filter as a simulated sunlight source. Turn on the xenon lamp and irradiate the tetracycline solution while stirring at 400 r / min for 1 h to degrade tetracycline. During this period, take 3 mL of tetracycline degradation solution every 10 min, test the absorbance and calculate the tetracycline removal rate.
[0055] Application Example 3
[0056] Take 12 mg of the porous carbon prepared in Examples 1 to 3 respectively, and add it to 100 mL of tetracycline solution with a concentration of 25 mg / L. Under dark conditions, stir at 500 r / min for 1 h to reach adsorption equilibrium. Then add 60 mg of persulfate. Use a 300 W xenon lamp with a Cut 420 nm filter as a simulated sunlight source. Turn on the xenon lamp and irradiate the tetracycline solution while stirring at 500 r / min for 1 h to degrade tetracycline. During this period, take 3 mL of tetracycline degradation solution every 10 min, test the absorbance and calculate the tetracycline removal rate.
[0057] Application Example 4
[0058] Take 14 mg of the porous carbon prepared in Examples 1 to 3 respectively, and add it to 100 mL of tetracycline solution with a concentration of 30 mg / L. Under dark conditions, stir at 600 r / min for 1 h to reach adsorption equilibrium. Then add 70 mg of persulfate. Use a 300 W xenon lamp with a Cut 420 nm filter as a simulated sunlight source. Turn on the xenon lamp and irradiate the tetracycline solution while stirring at 600 r / min for 1 h to degrade tetracycline. During this period, take 3 mL of tetracycline degradation solution every 10 min, test the absorbance and calculate the tetracycline removal rate.
[0059] Figure 6(a) shows the efficiency of the porous carbon prepared in Example 3 of Application Example 2 in activating persulfate to degrade tetracycline under light conditions. Meanwhile, the efficiency of the porous carbon prepared in Example 3 of Application Example 1 in activating persulfate to degrade tetracycline under dark conditions is compared. It can be seen that the porous carbon prepared in Example 3 can fully activate persulfate under light conditions, and the degradation efficiency of tetracycline reaches 91.0%, which is significantly higher than the degradation efficiency of 83% under darkness.
[0060] As can be seen from Figure 6(b), compared with the dark conditions, the degradation rate of tetracycline under light conditions is significantly faster, increasing by about 1.5 times. This indicates that the thermal effect generated by porous carbon under light and its own activation performance synergistically enhance the activation effect of PDS, achieving efficient degradation of tetracycline.
Claims
1. A method for preparing porous carbon with photothermal properties, characterized in that, Includes the following steps: Step 1: Mix NaCl and KCl in a mass ratio of 1:1 to obtain a mixed salt; Step 2: Mix sodium lignosulfonate and mixed salt evenly according to a mass ratio of 1:(3-5), spread the mixture in a ceramic boat, place the ceramic boat in a muffle furnace, and heat it from room temperature to 300-500℃ at a heating rate of 3-5℃ / min under a N2 atmosphere. Hold the temperature for 5-7 hours, and then cool it to room temperature with the furnace to obtain a black reactant. Step 3: Under ultrasonic assistance, the black reactant is washed several times and dried to obtain porous carbon.
2. The method for preparing porous carbon with photothermal properties according to claim 1, characterized in that, The cleaning in step 3 involves washing three times each with a 1 mol / L HCl solution and pure water.
3. The method for preparing porous carbon with photothermal properties according to claim 1, characterized in that, The drying in step 3 is carried out at 80-100℃ for 12 hours.
4. A porous carbon with photothermal properties prepared by the method according to any one of claims 1 to 3.
5. The application of porous carbon with photothermal properties according to claim 4, characterized in that, The process includes the following steps: adding porous carbon to tetracycline wastewater, stirring in the dark to allow the tetracycline to be fully adsorbed by the porous carbon, then adding persulfate to the tetracycline wastewater, and stirring under simulated sunlight to degrade the tetracycline pollutants in the wastewater.
6. The application of porous carbon with photothermal properties according to claim 5, characterized in that, The tetracycline concentration in the tetracycline wastewater is 20-30 mg / L, the ratio of porous carbon to tetracycline wastewater is (0.1-0.14 g): 1 L, and the ratio of persulfate to tetracycline wastewater is (0.5-0.7 g): 1 L.
7. The application of porous carbon with photothermal properties according to claim 5, characterized in that, Both the initial and subsequent stirring were performed at a speed of 400–600 r / min for 1 hour.
8. The application of porous carbon with photothermal properties according to claim 5, characterized in that, The simulated solar light source is a xenon lamp with an operating current of 15-20A and a rated power of 300W.