A quinone-rich modified biochar, its preparation method and application

Abstract

This invention relates to the field of wetland ecological restoration technology, and particularly to a quinone-enriched modified biochar, its preparation method, and its application. In this invention, *Spartina alterniflora* is pyrolyzed under an inert atmosphere to obtain *Spartina alterniflora*-based biochar; the *Spartina alterniflora*-based biochar is then immersed in an anthraquinone-2-sulfonic acid solution to react and obtain quinone-enriched *Spartina alterniflora* biochar. This invention utilizes anthraquinone-2-sulfonic acid to modify the biochar, significantly increasing the surface quinone content, which effectively promotes the reduction-oxidation cycle of iron in sediments. The quinone-enriched modified biochar provides additional electron shuttle pathways, accelerating the iron cycling process, increasing the content of amorphous iron, and promoting the iron cycle and the formation and transformation of iron minerals. Through the promotion of iron cycling, the proportion of iron-bound organic carbon and recalcitrant organic carbon is increased, improving the fixation efficiency and stability of soil organic matter (SOC).

Description

Technical Field

[0001] This invention relates to the field of wetland ecological restoration technology, and in particular to a quinone-rich modified biochar, its preparation method, and its application. Background Technology

[0002] Coastal wetlands, as key ecosystems in the marine-terrestrial ecotone, play a vital role in the global carbon cycle. Their sedimentary environments effectively sequester organic carbon through physical, chemical, and biological processes, which is of great significance for mitigating climate change. However, under the dual pressures of climate change and human activities, coastal wetlands face the problem of carbon sequestration degradation.

[0003] Coastal wetlands are typical iron-rich environments, and the iron cycle plays a crucial role in wetland carbon fixation. Microbial-mediated iron reduction-oxidation processes can be closely coupled with organic carbon transformation: in anaerobic environments, dissimilatory iron-reducing bacteria utilize ferric oxides as electron acceptors to decompose organic matter, while the resulting ferrous iron can form iron minerals through chemical oxidation or the action of iron-oxidizing bacteria, thereby binding and protecting organic carbon. However, coastal wetland sediments often suffer from insufficient iron reduction activity and low iron mineral regeneration efficiency, limiting the iron-mediated carbon fixation function.

[0004] Biochar, with its porous structure and abundant surface functional groups, is widely used for soil improvement and carbon fixation. However, ordinary biochar has limited effectiveness in promoting iron cycling, and its adaptability varies significantly under different water depth conditions. Existing technologies enhance biochar performance through acid modification and metal loading, but these methods suffer from problems such as complex preparation processes, high costs, and potential introduction of secondary pollution.

[0005] Anthraquinone-2-sulfonic acid, as a quinone redox mediator, can effectively promote electron transfer processes in microorganisms. However, direct addition easily leads to loss and decomposition, making it difficult to maintain its effectiveness. Therefore, developing a carbon fixation material that can stably and sustainably promote iron cycling in coastal wetland sediments is of great significance. Summary of the Invention

[0006] The purpose of this invention is to provide a quinone-rich modified biochar, its preparation method, and its application, in order to solve the problems of insufficient iron cycling activity and decreased carbon fixation capacity in coastal wetland sediments.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0008] This invention provides a method for preparing quinone-rich modified biochar, comprising the following steps:

[0009] Pyrolysis of Spartina alterniflora under an inert atmosphere yields Spartina alterniflora-based biochar.

[0010] Spartina alterniflora-based biochar was immersed in anthraquinone-2-sulfonic acid solution to carry out the reaction, thus obtaining Spartina alterniflora biochar enriched with quinone.

[0011] Optionally, the pyrolysis parameters are: heating to 500±10℃ at a rate of 10±2℃ / min, and pyrolysis time of 60min.

[0012] Optionally, the anthraquinone-2-sulfonic acid solution is prepared by dissolving sodium anthraquinone-2-sulfonate in water to obtain the anthraquinone-2-sulfonic acid solution.

[0013] Optionally, the concentration of the anthraquinone-2-sulfonic acid solution is 3 mmol / L.

[0014] Optionally, the reaction is carried out at room temperature for 2 hours and at a rotation speed of 120±10 rpm.

[0015] The present invention also provides quinone-rich modified biochar prepared by the above preparation method.

[0016] This invention also provides the application of the above-mentioned quinone-rich modified biochar in promoting iron cycling and enhancing carbon sequestration capacity in coastal wetland sediments.

[0017] Optionally, quinone-rich modified biochar is applied at a rate of 3.5 kg / m³. 2 Application to coastal wetland sediments.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) The present invention utilizes anthraquinone-2-sulfonic acid to modify biochar, which significantly increases the content of quinone groups on the surface and can effectively promote the reduction-oxidation cycle of iron in sediments;

[0020] (2) Quinone-rich modified biochar provides additional electron shuttle pathways, accelerates the iron cycling process, increases the content of amorphous iron, and promotes the iron cycling and the formation and transformation of iron minerals;

[0021] (3) By promoting iron cycling, the proportion of iron-bound organic carbon and recalcitrant organic carbon is increased, thereby improving the fixation efficiency and stability of soil organic matter (SOC).

[0022] (4) This invention explores different water depth conditions and can achieve good carbon fixation effect in both shallow and deep water environments;

[0023] (5) By using the invasive species Spartina alterniflora as raw material, waste resources can be utilized. The preparation method is simple, environmentally friendly, and low in cost. Attached Figure Description

[0024] Figure 1The carbonyl content (containing quinone groups) of biochar modified with anthraquinone-2-sulfonic acid solutions of different concentrations was determined.

[0025] Figure 2 The carbonyl content (including quinone groups) of modified biochar prepared at different temperatures was determined. Detailed Implementation

[0026] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0027] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0028] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0029] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0030] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0031] All raw materials used in this invention can be obtained commercially or prepared using existing technologies.

[0032] The room temperature described in the embodiments of the present invention is 25±2℃.

[0033] This invention provides a method for preparing quinone-rich modified biochar, comprising the following steps:

[0034] Pyrolysis of Spartina alterniflora under an inert atmosphere yields Spartina alterniflora-based biochar.

[0035] Spartina alterniflora-based biochar was immersed in anthraquinone-2-sulfonic acid solution to carry out the reaction, thus obtaining Spartina alterniflora biochar enriched with quinone.

[0036] This invention involves collecting Spartina alterniflora, an invasive plant from coastal wetlands, washing it with deionized water, drying it at 60°C for 24 hours, pulverizing it through a 100-mesh sieve, and then pyrolyzing the dried Spartina alterniflora under an inert atmosphere. After naturally cooling to room temperature, Spartina alterniflora biochar is obtained.

[0037] In this invention, Spartina alterniflora, a common invasive plant in coastal wetlands, is used to prepare biochar.

[0038] In this invention, the inert atmosphere includes nitrogen; the flow rate of the inert atmosphere is 0.5 L / min.

[0039] In this invention, the pyrolysis parameters are: heating to 500±10℃ at a rate of 10±2℃ / min, and pyrolysis time of 60min.

[0040] This invention involves immersing Spartina alterniflora-based biochar in an anthraquinone-2-sulfonic acid solution at room temperature with continuous mechanical stirring to ensure sufficient contact and loading of the anthraquinone-2-sulfonic acid molecules onto the biochar surface. After the reaction, the mixture is vacuum-filtered to separate the solid and liquid phases. The resulting solid product is repeatedly washed with ultrapure water. Finally, the solid is dried at 60°C for 24 hours, ground, and sieved to obtain quinone-rich Spartina alterniflora biochar.

[0041] In this invention, the anthraquinone-2-sulfonic acid solution is prepared by dissolving sodium anthraquinone-2-sulfonate in ultrapure water to obtain the anthraquinone-2-sulfonic acid solution.

[0042] In an embodiment of the present invention, the purity of the anthraquinone-2-sulfonate sodium salt is 98%.

[0043] In this invention, the concentration of the anthraquinone-2-sulfonic acid solution is 3 mmol / L.

[0044] In this invention, the reaction temperature is room temperature, the time is 2 hours, and the rotation speed is 120±10 rpm.

[0045] The present invention also provides quinone-rich modified biochar prepared by the above preparation method.

[0046] This invention also provides the application of the above-mentioned quinone-rich modified biochar in promoting iron cycling and enhancing carbon sequestration capacity in coastal wetland sediments.

[0047] In this invention, quinone-rich modified biochar is applied at a rate of 3.5 kg / m³. 2Application to coastal wetland sediments.

[0048] In this invention, biochar is mixed with sediment under shallow water conditions (1-2 cm) and deep water conditions (20 cm water layer).

[0049] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0050] Example 1

[0051] (1) Preparation of Spartina alterniflora-based biochar: Spartina alterniflora, an invasive plant in coastal wetlands, was collected, washed with deionized water, dried in an oven at 60℃ for 24h, pulverized and passed through a 100-mesh sieve; 200g of Spartina alterniflora powder was placed in a tube furnace, heated to 500℃ at 10℃ / min under a nitrogen atmosphere (flow rate 0.5L / min), pyrolyzed at a constant temperature for 60min, and naturally cooled to room temperature to obtain Spartina alterniflora-based biochar, which was then ground and passed through a 100-mesh sieve for later use;

[0052] (2) Preparation of anthraquinone-2-sulfonic acid modified solution: Accurately weigh 0.726 g of anthraquinone-2-sulfonate sodium salt (purity 98%), dissolve it in 1 L of ultrapure water, and prepare an anthraquinone-2-sulfonic acid solution of 3 mmol / L;

[0053] (3) Preparation of quinone-rich Spartina alterniflora biochar: Weigh 50 g of pretreated Spartina alterniflora-based biochar and immerse it in freshly prepared (2) modified solution. Under room temperature (25±2°C), mechanically stir at 120 rpm for 2 hours to ensure sufficient contact and loading of anthraquinone-2-sulfonic acid molecules on the biochar surface. After the reaction, vacuum filter the mixture to separate the solid and liquid phases, and wash the obtained solid product repeatedly with ultrapure water. Finally, transfer the material to a 60°C forced-air drying oven and dry for 24 hours. After grinding, sieve to obtain the quinone-rich Spartina alterniflora biochar product.

[0054] Test Example 1: The promoting effect of quinone-rich modified biochar on iron cycling and carbon sequestration in sediments under shallow water conditions

[0055] Experimental Design:

[0056] The experimental sediments were collected from the intertidal zone of a coastal wetland (0-20cm surface sediments).

[0057] Set up 3 processing groups:

[0058] (1) Control group: No biochar added;

[0059] (2) Ordinary biochar group: based on 3.5 kg / m 2 Apply unmodified Spartina alterniflora biochar;

[0060] (3) Quinone-rich biochar group: at 3.5 kg / m 2 Apply quinone-rich modified Spartina alterniflora biochar.

[0061] Each group had three replicates. The sediment was air-dried, ground, and sieved through a 2mm sieve. Biochar was added according to the above proportions, and the mixture was thoroughly stirred before being placed into a custom-designed microcosm device (15cm in diameter, 20cm in height). Artificial seawater was added to maintain a 1–2cm water layer on the sediment surface. The device was placed in an artificial climate chamber to simulate natural light-dark cycles (12h / 12h) and temperature variations (25±2℃). The experiment lasted 90 days, with samples taken at days 0, 30, 60, 90, and 120 to measure relevant indicators.

[0062] Measurement method:

[0063] (1) Amorphous iron content: after extraction by oxalate and dithionite methods, the content was determined by o-phenanthroline spectrophotometry;

[0064] (2) Total organic carbon content: determined by an elemental analyzer;

[0065] (3) Content of recalcitrant organic carbon: determined by external heating method with potassium dichromate;

[0066] (4) Iron-bound organic carbon content: The extract was obtained by sodium dithionite-sodium citrate-sodium bicarbonate method, and the organic carbon content in the extract was determined by a TOC analyzer.

[0067] (5) The content of divalent iron and total iron was determined by the o-phenanthroline spectrophotometric method.

[0068] result:

[0069] Table 1. Variation of organic carbon content in sediments from different experimental groups under shallow water conditions (all units are g / kg)

[0070]

[0071] Table 2. Changes in iron speciation in sediments from different experimental groups under shallow water conditions (all units are g / kg)

[0072]

[0073] The results showed that the addition of quinone-enriched modified biochar significantly promoted the carbon fixation process in sediments. The total organic carbon content increased by 93.07% compared to the control group and by 8.32% compared to the ordinary biochar group; the iron-bound organic carbon content increased by 113.19% compared to the control group and by 21.9% compared to the ordinary biochar group. Furthermore, the ratio of recalcitrant organic carbon to total organic carbon increased from 68.89% in the control group to 74.07%, indicating that quinone-enriched modified biochar particularly promoted the formation of iron-bound organic carbon and improved the stability of organic carbon.

[0074] Monitoring of ferrous iron (Fe2+) and total iron concentrations showed that the quinone-rich biochar group had the highest contents, with ferrous iron concentrations of 3.09±0.35 g / kg and total iron concentrations of 4.93±0.48 g / kg, respectively. This indicates that quinone-rich modification significantly enhanced the iron cycling process. After 120 days, the non-static iron oxide content in the quinone-rich biochar group increased by 295.24% compared to the control group and by 36% compared to the ordinary biochar group, indicating that iron oxidation and mineral formation processes occurred.

[0075] Test Example 2: The Promoting Effect of Quinone-Enriched Modified Biochar on Iron Cycling and Carbon Sequestration in Sediments under Deep-Water Conditions

[0076] Experimental Design:

[0077] The experimental sediments were collected from the intertidal zone of a coastal wetland (0-20cm surface sediments).

[0078] (1) Control group: No biochar added;

[0079] (2) Ordinary biochar group: based on 3.5 kg / m 2 Apply unmodified Spartina alterniflora biochar;

[0080] (3) Quinone-rich biochar group: at 3.5 kg / m 2 Apply quinone-rich modified Spartina alterniflora biochar.

[0081] Each group had 3 parallel experiments. The experimental setup and method were the same as in Test Example 1, except that the water depth was adjusted to 20 cm to simulate a deep-water environment. The experiment lasted for 90 days, with samples taken and measured at 0, 30, 60, 90, and 120 days.

[0082] result:

[0083] Table 3. Variation of organic carbon content in sediments from different experimental groups under deep-water conditions (all units are g / kg)

[0084]

[0085] Table 4. Changes in iron speciation in sediments from different experimental groups under deep-water conditions (all units are g / kg)

[0086]

[0087] Under deep-water conditions, the quinone-rich biochar group also exhibited a good promoting effect. After 120 days, the amorphous iron oxide content in the quinone-rich biochar group increased by 205.26% compared to the control group and by 38.10% compared to the ordinary biochar group; the total organic carbon content increased by 64.43% compared to the control group and by 7.00% compared to the ordinary biochar group; and the iron-bound organic carbon content increased by 68.33% compared to the control group and by 15.53% compared to the ordinary biochar group. The ratio of recalcitrant organic carbon to total organic carbon in the quinone-rich biochar group increased from 52.93% in the control group to 69.67%, indicating that the quinone-rich biochar also promoted the formation of iron-bound organic carbon and improved the stability of organic carbon under deep-water submersion conditions.

[0088] Compared to Test Example 1, the carbon fixation effect of conventional bio-enhanced biochar decreased under deep-water conditions (all organic carbon indicators were lower than those of the control group in Test Example 1), but quinone-rich biochar still maintained good performance, indicating that it has better adaptability and stability under different water depths. This may be because the electron shuttle function provided by the quinone-rich groups alleviates the limitation of the redox potential gradient caused by water depth on the iron reduction process.

[0089] Example 2

[0090] Anthraquinone-2-sulfonic acid solutions of different concentrations mixed with biochar

[0091] (1) Preparation of Spartina alterniflora-based biochar: Same as step (1) in Example 1, to obtain Spartina alterniflora-based biochar for later use.

[0092] (2) Preparation of anthraquinone-2-sulfonic acid modified solutions of different concentrations:

[0093] Low concentration group (1 mmol / L): Accurately weigh 0.242 g of anthraquinone-2-sulfonate sodium salt (98% purity) and dissolve it in 1 L of ultrapure water.

[0094] Medium concentration group (3 mmol / L, baseline group): Same as in Example 1, accurately weigh 0.726 g of anthraquinone-2-sulfonate sodium salt and dissolve it in 1 L of ultrapure water.

[0095] High concentration group (5 mmol / L): Accurately weigh 1.210 g of anthraquinone-2-sulfonate sodium salt (98% purity) and dissolve it in 1 L of ultrapure water.

[0096] (3) Preparation of quinone-enriched Spartina alterniflora biochar: Three 50g portions of Spartina alterniflora-based biochar were weighed and immersed in the above-mentioned 1mmol / L, 3mmol / L, and 5mmol / L anthraquinone-2-sulfonic acid solutions, respectively. The mixture was mechanically stirred at 120±10 rpm for 2 hours at room temperature (25±2°C). After the reaction, the mixture was vacuum filtered, the solid was washed with ultrapure water, dried at 60°C for 24 hours, ground, and sieved to obtain three quinone-enriched modified biochars with different loading concentrations. The content of carbonyl groups (containing quinone groups) on the surface of the biochar was determined by Boehm titration.

[0097] Application effect test:

[0098] The experimental design was the same as in Example 1, with shallow water conditions. The sediments were from the intertidal zone of a coastal wetland, and five treatment groups were set up for comparison:

[0099] (1) Control group: No biochar added;

[0100] (2) Ordinary biochar group: unmodified Spartina alterniflora biochar (3.5 kg / m²) was applied;

[0101] (3) Low concentration modified biochar group: 1 mmol / L modified biochar (3.5 kg / m²) was applied.

[0102] (4) Medium concentration modified biochar group: 3 mmol / L modified biochar (3.5 kg / m²) was applied.

[0103] (5) High concentration modified biochar group: 5 mmol / L modified biochar (3.5 kg / m²) was applied.

[0104] Each group had 3 replicates, under shallow water conditions (1-2 cm water layer), and the experiment lasted for 120 days. Total organic carbon, iron-bound organic carbon, and amorphous iron were measured.

[0105] Table 5. Effects of different concentrations of modified biochar on the organic carbon content of sediments under shallow water conditions (120-day data, unit: g / kg)

[0106]

[0107] Table 6. Effects of different concentrations of modified biochar on iron speciation in sediments under shallow water conditions (120-day data, unit: g / kg)

[0108]

[0109] All quinone-enriched modified biochar groups (1, 3, 5 mmol / L) showed significantly better performance than the ordinary biochar group, demonstrating the universal applicability of anthraquinone-2-sulfonic acid modification in improving biochar performance. The 3 mmol / L group exhibited the best effect, with the highest total organic carbon, iron-bound organic carbon, and amorphous iron oxide content. Compared to the ordinary biochar group, total organic carbon increased by 8.32%, and iron-bound organic carbon increased by 21.9%. While low-concentration modified biochar was superior to ordinary biochar, its effect was significantly lower than the 3 mmol / L group, indicating that the low concentration resulted in insufficient quinone group loading on the biochar surface, limiting its electron shuttle capability. The high-concentration modified biochar showed effects very close to the 3 mmol / L group, but still lower than the medium-concentration modified biochar group. This suggests that under the stated preparation conditions, a concentration of 3 mmol / L is sufficient to saturate the quinone group loading on the biochar surface; further increases in concentration have limited performance improvement. From a cost-effectiveness perspective, 3 mmol / L is the more economical and preferred concentration.

[0110] Figure 1 The carbonyl content (containing quinone groups) of biochar modified with anthraquinone-2-sulfonic acid solutions of different concentrations is determined by... Figure 1 It was found that the concentration of the modified solution had a significant impact on the carbonyl content on the biochar surface. Specifically, when the concentration of anthraquinone-2-sulfonic acid increased from 1 mmol / L to 3 mmol / L, the carbonyl content increased significantly, reaching a peak at 3 mmol / L (average value 0.257 mmol / g); while when the concentration was further increased to 5 mmol / L, the carbonyl content decreased slightly (average value 0.25 mmol / g). This indicates that a 3 mmol / L anthraquinone-2-sulfonic acid solution can most effectively promote the loading of functional groups on the biochar surface, thereby optimizing its electron shuttle capability, consistent with the optimal concentration described in Example 2. This result verifies that 3 mmol / L is an economical and efficient modification concentration, providing a key parameter basis for improving the performance of biochar.

[0111] Example 3

[0112] Different biochar preparation conditions

[0113] (1) Preparation of Spartina alterniflora-based biochar: Spartina alterniflora was collected, washed, dried, and pulverized through a 100-mesh sieve. 200g of powder was placed in a tube furnace under a nitrogen atmosphere (flow rate 0.5L / min):

[0114] Low temperature group: The temperature was increased to 300℃ at a rate of 10℃ / min, and then pyrolyzed at a constant temperature for 60min.

[0115] Medium temperature group: The temperature was increased to 500℃ at 10℃ / min (same as in Example 1), and pyrolysis was carried out at a constant temperature for 60min.

[0116] High temperature group: Heat up to 700℃ at 10℃ / min and keep at a constant temperature for 60min.

[0117] After natural cooling, the material is ground and sieved to obtain charcoal from Spartina alterniflora at different pyrolysis temperatures.

[0118] (2) Preparation of anthraquinone-2-sulfonic acid modified solution: Same as in Example 1, prepare a 3 mmol / L solution.

[0119] (3) Preparation of quinone-rich Spartina alterniflora biochar: 50g of raw biochar prepared at 300℃, 500℃, and 700℃ were respectively immersed in anthraquinone-2-sulfonic acid solution and stirred at 120±10rpm for 2 hours at room temperature. The post-treatment was the same as in Example 1 to obtain three kinds of quinone-rich modified biochar with different pyrolysis temperatures, and the carbonyl (quinone-containing) content on the surface of the biochar was determined by Boehm titration.

[0120] Application effect test:

[0121] The experimental design was the same as in Example 1, with shallow water conditions. The sediments were from the intertidal zone of a coastal wetland, and five treatment groups were set up for comparison:

[0122] (1) Control group: No biochar added;

[0123] (2) Ordinary biochar group: Apply 3.5 kg / m² of unmodified Spartina alterniflora biochar at 500℃;

[0124] (3) Low-temperature modified biochar group: 300℃ modified biochar (3.5kg / m²) was applied.

[0125] (4) Medium-temperature modified biochar group: 500℃ modified biochar (3.5kg / m²) was applied.

[0126] (5) High temperature modified biochar group: Apply 700℃ modified biochar (3.5kg / m²).

[0127] Each group had 3 replicates, under shallow water conditions (1-2 cm water layer), and the experiment lasted for 120 days. Total organic carbon, iron-bound organic carbon, and amorphous iron were measured.

[0128] Table 7 Effects of modified biochar at different temperatures on organic carbon content in sediments under shallow water conditions (120-day data, unit: g / kg)

[0129]

[0130] Table 8 Effect of modified biochar at different temperatures on iron speciation in sediments under shallow water conditions (120-day data, unit g / kg)

[0131]

[0132] Data shows that the modified biochar prepared in the medium-temperature group performed best in all key indicators. The low-temperature group may have had limited improvement in modification effect due to insufficient development of the biochar's pore structure and surface functional groups. Although the high-temperature group could form well-developed pores, changes in surface chemical properties (such as a reduction in oxygen-containing functional groups) may have been detrimental to the stable loading of quinone groups, resulting in a slightly inferior effect compared to the 500℃ group. This result further verifies that 500℃ is the optimal pyrolysis temperature, which, together with the conclusion of Example 2 (3 mmol / L being the optimal concentration), constitutes the optimal process parameters of this invention.

[0133] Figure 2 The carbonyl content (including quinone groups) of modified biochar prepared at different temperatures was determined by... Figure 2 It is evident that pyrolysis temperature significantly affects the carbonyl content on the surface of biochar. Among the three temperatures of 300℃, 500℃, and 700℃, biochar prepared by pyrolysis at 500℃ exhibited the highest carbonyl content after modification (average value 0.257 mmol / g), while the carbonyl content in the 300℃ and 700℃ groups was relatively lower. This may be because pyrolysis at 500℃ can form suitable porous structures and functional groups on the biochar surface, which is beneficial for the stable loading of anthraquinone-2-sulfonic acid; low-temperature pyrolysis may lead to insufficient structural development, while high-temperature pyrolysis may reduce the number of oxygen-containing functional groups on the surface. This result echoes the conclusions of Example 3, confirming that 500℃ is the optimal pyrolysis temperature, ensuring the best performance of quinone-enriched modified biochar in promoting iron cycling and carbon fixation.

[0134] Examples 2 and 3 systematically investigated two key parameters: modifier concentration and pyrolysis temperature. The results showed that modifying *Spartina alterniflora* biochar prepared by pyrolysis at 500℃ with a 3 mmol / L anthraquinone-2-sulfonic acid solution was the optimal process combination for preparing high-performance quinone-rich modified biochar. The material obtained under this combination showed the most outstanding performance in promoting iron cycling and enhancing carbon sequestration capacity in coastal wetland sediments, and also exhibited good adaptability under different water depth conditions. This provides important parameter basis for the standardized application and promotion of this technology.

[0135] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. The application of quinone-enriched modified biochar in promoting iron cycling and enhancing carbon sequestration capacity in coastal wetland sediments, characterized in that, The method for preparing the quinone-rich modified biochar includes the following steps: Pyrolysis of Spartina alterniflora under an inert atmosphere yields Spartina alterniflora-based biochar. Spartina alterniflora-based biochar was immersed in anthraquinone-2-sulfonic acid solution to carry out the reaction, thus obtaining Spartina alterniflora biochar enriched with quinone.

2. The application according to claim 1, characterized in that, The pyrolysis parameters are: heating to 500±10℃ at a rate of 10±2℃ / min, and pyrolysis time of 60min.

3. The application according to claim 1, characterized in that, The anthraquinone-2-sulfonic acid solution is prepared by dissolving sodium anthraquinone-2-sulfonate in water to obtain the anthraquinone-2-sulfonic acid solution.

4. The application according to claim 1, characterized in that, The concentration of the anthraquinone-2-sulfonic acid solution was 3 mmol / L.

5. The application according to claim 1, characterized in that, The reaction was carried out at room temperature for 2 hours and at a rotation speed of 120±10 rpm.

6. The application according to claim 1, characterized in that, The quinone-enriched modified biochar was applied at 3.5 kg / m 2 Application to coastal wetland sediments.

Images