Method for enhancing aerobic composting humification and greenhouse gas emission reduction based on iron-manganese doped porous material
By preparing iron-manganese-doped porous materials, constructing a multi-level pore system and bimetallic active sites, the problem of redox environment regulation during composting was solved, achieving humification promotion and greenhouse gas emission reduction, and improving the quality and efficiency of compost products.
Patent Information
- Application Number
- CN202511970740.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-25
- Publication Date
- 2026-02-27
AI Technical Summary
Existing technologies struggle to effectively regulate the redox environment during composting, leading to excessive mineralization of organic matter and excessive greenhouse gas emissions. Furthermore, iron and manganese elements migrate and are lost within the compost pile, resulting in a short-lived and uncontrollable catalytic effect, making it difficult to achieve a synergistic effect of promoting humification and reducing emissions.
By preparing iron-manganese-doped porous materials, a multi-level pore system and synergistic formation of bimetallic active sites are constructed to precisely regulate the redox microenvironment during composting, thereby promoting humification synthesis and inhibiting greenhouse gas production.
It increases humic acid content, reduces CO2, CH4 and N2O emissions, shortens composting time, improves the stability of compost products and seed germination index, and the material is recyclable without changing the existing composting process.
Smart Images
Figure CN121574013A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the technical field of organic solid waste resource processing, and particularly relates to a method for regulating aerobic composting by adding a specific functional material, and especially relates to a compost additive capable of promoting humus synthesis and reducing greenhouse gas emissions, and preparation and application thereof. BACKGROUND
[0002] Aerobic composting is an important technology for realizing stabilization, harmlessness and resource utilization of perishable garbage. However, the traditional process has the following defects: 1) excessive mineralization of organic matter leads to large emission of carbon dioxide (CO2); 2) uneven mass transfer in the pile forms local anaerobic microzones, producing methane (CH4), nitrous oxide (N2O) and other strong greenhouse gases; 3) the humification process is slow and incomplete, and the quality of the compost product is unstable.
[0003] Existing technologies mostly use physical adsorption type additives (such as zeolite, biochar) to alleviate greenhouse gas emissions or regulate moisture, and are difficult to actively regulate the core biochemical process of the composting system. In particular, at the low temperature stage (25-65℃) of composting, there is a lack of an effective means that can gently and continuously regulate the oxidation-reduction environment, thereby guiding the transformation of small molecular organic matter towards polymerization and condensation (humification) rather than complete mineralization.
[0004] Iron and manganese elements have significant potential in catalyzing the oxidative coupling reaction of precursors such as phenols and amino phenols due to their variable valence and good oxidation-reduction characteristics. However, iron and manganese ions are easily lost by migration in the pile and inactivated by being wrapped by organic matter, making it difficult to form a stable oxidation-reduction gradient in the pile, resulting in short-term, local and uncontrollable catalytic effect. In addition, conventional loading methods often cannot achieve the synergistic distribution of iron and manganese active species in space and valence, limiting their multi-target regulation ability in complex composting systems. Therefore, how to convert them into a regulation material suitable for the complex composting system in a low-cost and stable process, and achieve the multi-target synergy of humification promotion and emission reduction, is still a technical bottleneck currently faced. SUMMARY
[0005] The present application aims to overcome the deficiencies of the prior art and provide an easy-to-decompose garbage aerobic composting regulation method with simple process and synergistic effect. The method uses an iron-manganese doped porous material with a specific structure to directionally strengthen the humification synthesis path and effectively inhibit the generation and emission of greenhouse gases under conventional composting conditions.
[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solutions.
[0007] In a first aspect, the present application provides a preparation method of the above-mentioned iron-manganese doped porous material. The material uses a silicon-aluminum oxide porous carrier as a skeleton to construct a multi-level pore system; iron and manganese cooperatively form a bimetallic active site at the skeleton node, significantly improving the efficiency of electron / ion conduction and interface reaction, thereby constructing a precisely controllable redox microenvironment in the composting process. The preparation method comprises the following steps: S1, a porous carrier containing a silicon-aluminum oxide is subjected to selective etching treatment with an alkaline solution to construct a hierarchical pore structure; after neutralization, washing and acid site recovery treatment, drying is performed to obtain a pretreated carrier; S2, the pretreated carrier obtained in step S1 is immersed in a manganese salt solution under heating conditions to load manganese species on the surface and outer pores of the carrier; then an oxidation treatment is performed using a permanganate solution to convert the outer layer manganese into a high valence state; after the treatment is completed, washing is performed; S3, the material obtained in step S2 is immersed in an iron complex salt solution under heating conditions to make the iron species penetrate into the internal pores of the carrier; then a reducing agent solution is used for treatment to form a mixed valence state of the inner layer iron; after the treatment is completed, washing is performed; S4, the material obtained in step S3 is alternately immersed in a ferrous salt solution and a permanganate solution to in-situ synthesize iron-manganese composite oxyhydroxyl active clusters in the pores; then washing and drying are performed; S5, the dried material obtained in step S4 is first calcined in an air atmosphere and then activated in a water vapor atmosphere to obtain the iron-manganese doped porous material.
[0008] Preferably, in step S1, the alkaline solution is a NaOH solution with a concentration of 0.2-0.5 M, the etching treatment temperature is 50-65°C, and the treatment time is 10-40 minutes; the drying temperature is 120-200°C. The porous carrier is a zeolite, a molecular sieve or a porous ceramic.
[0009] Preferably, in step S2, the manganese salt solution has a concentration of 5-50 mM, the immersion temperature is 60-80°C, and the immersion time is 0.5-3 hours; the permanganate solution has a concentration of 0.5-2 mM, the oxidation treatment temperature is 40-70°C, and the treatment time is 10-60 minutes. The manganese salt is manganese acetate or manganese nitrate, and the permanganate is potassium permanganate.
[0010] Preferably, in step S3, the iron complex salt solution has a concentration of 5-50 mM, the immersion temperature is 80-90°C, and the immersion time is 0.5-3 hours; the reducing agent solution has a concentration of 5-20 mM, and the treatment time is 10-60 minutes. The iron complex salt is ferric citrate, and the reducing agent is ascorbic acid or glucose.
[0011] Preferably, in step S4, the ferrous salt solution is a 5-20 mM FeSO4 solution, the permanganate solution is a 0.2-1 mM KMnO4 solution, the time for each immersion is 5-10 minutes, and the number of alternating immersion cycles is 3-6; and the drying temperature is 100-120℃.
[0012] Preferably, in step S5, the calcination temperature is 350-450℃, the calcination time is 1.5-3 hours, the activation temperature is 120-200℃, and the activation time is 0.5-2 hours.
[0013] In a second aspect, the present application provides a method for using the iron-manganese doped porous material described above in aerobic composting, which specifically comprises the following steps: S1. Pre-treating organic waste by sorting, crushing and dewatering, controlling the particle size of the material to be ≤5 cm, the water content to be 50-60%, and the carbon-nitrogen ratio (C / N) to be 25-30; adding the iron-manganese doped porous material at a proportion of 1.0-3.0 wt% of the total mass of the composting raw material, and mixing uniformly; S2. Transferring the mixed material into a composting reactor, and performing intermittent aeration and turning. The aeration amount is 0.05 L / (min·L), the aeration frequency is 10-20 min / h, the turning frequency is 2-3 times per day, and the duration of the high-temperature period (50-70℃) of the pile is not less than 5 days; S3. After the temperature of the pile drops to room temperature, the composting is completed, and a matured organic fertilizer with a germination index greater than 80% and a water content less than 30% is obtained; S4. After maturation, the porous material can be recovered by screening, and can be regenerated by simple air oxidation or leaching with a low-concentration hydrogen peroxide solution, and can be repeatedly used for subsequent batches of composting, with the number of cycles of use usually being not less than 5.
[0014] The beneficial effects of the present application are as follows: (1) By constructing oxygen release and selective oxidation microzones, the oxidation coupling of precursors such as phenols and amino phenols is effectively guided, so that the content of humic acid in the composting product is increased by 5-18%, and the humus ratio is increased by 40-60%; (2) The excessive mineralization of organic matter and the local strict anaerobic environment are inhibited, so that the cumulative emission amount of CO2 during the entire composting process is reduced by 10-15%, the cumulative emission amount of CH4 is reduced by 12-17%, and the cumulative emission amount of N2O is reduced by 20-30%; (3) The metabolic environment of microorganisms is optimized, the time for composting to reach maturation is shortened by 3-5 days, the seed germination index (GI) of the final product is stabilized at more than 80%, the respiratory activity is reduced, and the product is more stable; (4) The amount of material added is small, the preparation process is mature, the existing composting process flow and facilities do not need to be changed during application, the operation is simple, and the material is suitable for various organic waste and easy to popularize. Attached Figure Description
[0015] Figure 1 This is a flowchart illustrating the preparation process of the iron-manganese-doped porous material of the present invention.
[0016] Figure 2 The images show the material diagram and SEM image of the iron-manganese-doped porous material of this invention.
[0017] Figure 3 This is a flowchart illustrating the application method of the iron-manganese-doped porous material of the present invention in aerobic composting. Detailed Implementation
[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the embodiments of this invention will be described in detail below with reference to examples. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention. Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the materials and reagents used are commercially available. Example 1
[0019] This embodiment specifically illustrates a method for preparing the iron-manganese doped porous control material of the present invention.
[0020] (1) Take 100 g of 13X molecular sieve with a particle size of 3-5 mm and place it in a reaction vessel. Add a 0.3 mol / L sodium hydroxide (NaOH) solution with a solid-liquid ratio of 1 g: 10 mL. Heat the mixture to 60 °C and maintain the temperature. Stir at 150 rpm and selectively etch for 30 minutes to construct a hierarchical pore structure dominated by mesopores in situ in the support. After etching, cool the mixture to room temperature and filter to separate the solid. Wash the solid with deionized water until the filtrate is neutral (pH≈7.0). Then transfer the solid to a 1.0 mol / L ammonium chloride (NH4Cl) solution and perform ion exchange at room temperature for 2 hours (repeated twice) to restore and enhance the Brønsted acidic sites on the support surface. After the exchange is completed, filter again and wash thoroughly with deionized water. Place the washed solid in an oven and dry at 120 °C for 6 hours to obtain a hierarchical pore pretreated support.
[0021] (2) The pretreated carrier after drying was immersed in a 0.05 mol / L manganese acetate (Mn(CH3COO)2·4H2O) aqueous solution (solid-liquid ratio 1 g: 15 mL) and was placed in a constant-temperature water bath at 80°C for 2 hours to allow manganese ions to be mainly adsorbed on the outer surface and shallow pores of the carrier. After the immersion, the carrier was filtered and washed with deionized water for 3 times. Subsequently, the carrier was transferred to a 1.0 mmol / L potassium permanganate (KMnO4) aqueous solution (solid-liquid ratio 1 g: 15 mL) and was stirred at 60°C for 30 minutes to convert the outer layer manganese species into a high-valence stable state mainly in the form of manganese dioxide (MnO2). After the oxidation, the carrier was filtered and washed with deionized water until the filtrate was colorless, to obtain the intermediate A modified with manganese on the outer layer.
[0022] (3) The intermediate A was immersed in a 0.05 mol / L iron citrate complex solution (molar ratio of citric acid to trivalent iron ions 2:1, solid-liquid ratio 1 g: 15 mL) at 90°C for 2 hours to allow iron species to be loaded into the pores of the carrier. After the immersion, the carrier was filtered and washed with deionized water for 3 times. Subsequently, the material was immersed in a 10 mmol / L ascorbic acid (C6H8O6) aqueous solution (solid-liquid ratio 1 g: 15 mL) and was treated at 70°C for 30 minutes to partially reduce the inner layer iron to form a mixed valence state of coexisting Fe(II) / Fe(III). After the treatment, the carrier was filtered and washed with deionized water to obtain the intermediate B modified with iron on the inner layer.
[0023] (4) The intermediate B was immersed in a 10 mmol / L ferrous sulfate (FeSO4·7H2O) aqueous solution (solid-liquid ratio 1 g: 15 mL) at room temperature for 5 minutes to allow ferrous ions to enter the pores. After being taken out and drained, the material was immersed in a 0.5 mmol / L potassium permanganate (KMnO4) aqueous solution (solid-liquid ratio 1 g: 15 mL) at room temperature for 5 minutes to generate iron-manganese complex oxyhydroxyl clusters in the pores by in-situ oxidation-reduction reaction of Fe 2+ and MnO4 - on the inner layer. The process was repeated 4 times, and the material was washed with deionized water repeatedly until the conductivity of the washing liquid was stable and close to the background value of deionized water. The washed wet material was placed in an oven and was dried at 110°C for 4 hours to obtain the precursor material loaded with iron-manganese active clusters.
[0024] (5) The dried precursor material was placed in a muffle furnace, and was heated to 400°C at a rate of 5°C / min under static air atmosphere, and was kept at this temperature for 2 hours to remove residual organic matter, crystallize and fix the morphology and structure of the metal active species. After natural cooling to room temperature, the material was transferred to a tube furnace, and was subjected to steam activation treatment at 150°C for 1 hour under constant water vapor generated by a saturated water vapor generator (carrier gas: air, gas velocity: 50 mL / min) to induce oxygen vacancies on the surface and bulk of the material, and to enhance its oxygen adsorption and reversible release capacity at low temperature. After the activation was completed, the material was cooled to room temperature under inert atmosphere to obtain the final iron-manganese doped porous material of the example. Example 2
[0025] In this example, the iron-manganese doped porous material prepared in Example 1 was applied to aerobic composting of perishable garbage, and the effect was verified. The specific steps are as follows.
[0026] (1) Perishable garbage (mainly composed of vegetable stems and leaves, fruit peel garbage and kitchen garbage) was collected, and impurities such as plastic and metal were removed by manual sorting. The perishable garbage was crushed to a particle size of ≤5 cm by a crusher. The crushed perishable garbage was mixed with tree leaves pruned in gardens, and the C / N ratio of the mixture was adjusted to 25 and the moisture content was adjusted to 60% to obtain compost raw materials. According to 2% of the total mass of the compost raw materials, the prepared iron-manganese doped porous material was weighed as an additive, and a mechanical stirring device was used to mix the additive and the compost raw materials uniformly to obtain a compost mixture. At the same time, a group of raw materials without any additive was set as a blank control group.
[0027] (2) The above mixture was respectively loaded into two identical cylindrical forced ventilation static composting reactors for aerobic composting. The compost was subjected to intermittent aeration mode, and air was introduced into the reactor from the lower end of the aeration pipe and was discharged from the upper end of the outlet by a fan, and the aeration amount was 0.05 L / (min·L), and the aeration frequency was 15 min / h. According to the temperature change of the compost, manual turning was carried out every 2-3 days. The temperature at the center of the compost was monitored daily by a temperature sensor inserted into the compost.
[0028] (3) The composting period was 24 days. The moisture content, carbon-nitrogen ratio (C / N), humic acid content and humus ratio of the compost were determined by periodic sampling, and the concentrations of CO2, CH4 and N2O in the exhaust gas were collected and analyzed by gas chromatography, and the cumulative emission amount and the emission reduction rate relative to the blank control group were calculated during the entire composting period. After the composting was completed, the seed germination index (GI) of the product was determined.
[0029] The experimental results are shown in Table 1.
[0030]
[0031] As can be seen from Table 1, compared with the blank group, the test group adding the iron-manganese doped porous material of the application has obvious improvement in humic acid content and humus ratio, which shows that the material helps to promote the synthesis and stabilization of humus in the composting process. At the same time, the test group shows good effect in reducing the emission of three kinds of greenhouse gases CO2, CH4 and N2O, which verifies the comprehensive advantages of the material of the application in improving the quality of compost and realizing the coordinated reduction of greenhouse gases. Example 3
[0032] This example illustrates the regeneration and recycling performance of the iron-manganese doped porous material of the application.
[0033] The material after the composting in Example 2 is screened to recover the porous material particles. The recovered material is uniformly sprayed with 1% hydrogen peroxide (H2O2) solution, and then dried in a ventilated environment for 24 hours to complete the regeneration treatment.
[0034] The regenerated porous material is applied to a batch of new composting materials with the same addition ratio (2% of wet basis mass) as the raw materials in Example 2, and the composting experiment is repeated. After 3 batches of recycling use, the test results show that the regenerated material has less than 15% attenuation in promoting the synthesis of humic acid and reducing the emission of greenhouse gases (CO2, CH4) compared with the first use, which proves that it has good regeneration performance and recycling stability.
[0035] The above examples are only used to illustrate the principles and effects of the application, and are not used to limit the application. For those skilled in the art, the above examples can be changed, modified, replaced and modified without departing from the spirit and essence of the application. The protection scope of the application is defined by the appended claims and their equivalents.
Claims
1. The application of an iron-manganese-doped porous material in aerobic composting, characterized in that, The material uses a porous silicon-aluminum oxide carrier as a framework and has a multi-level pore system. Iron and manganese are fixed at the framework nodes through doping and synergistically form bimetallic active sites. During composting, a controllable redox microenvironment is established. Through slow oxygen release and selective oxidation, the organic matter conversion pathway is regulated at the microscale, thereby enhancing the humification process and reducing greenhouse gas emissions. The preparation method of the iron-manganese doped porous material includes the following steps: S1. Selectively etch a porous carrier containing silicon aluminum oxide with an alkaline solution to construct a hierarchical pore structure; after neutralization, washing and acid site recovery treatment, dry to obtain a pretreated carrier; S2. The pretreated carrier is impregnated with a manganese salt solution under heating conditions to load manganese species onto the carrier surface and outer pores; then it is oxidized with a permanganate solution to convert the outer manganese into a high valence state, and after washing, intermediate A is obtained. S3. The intermediate A is impregnated with an iron complex salt solution under heating conditions to allow the iron species to penetrate deep into the internal pores of the carrier; then it is treated with a reducing agent solution to make the inner iron form a mixed valence state, and after washing, intermediate B is obtained. S4. The intermediate B is alternately impregnated in ferrous salt solution and permanganate solution to synthesize iron-manganese composite oxygen-hydroxyl active clusters in situ within the channels; the material is then washed and dried to obtain the precursor material. S5. The precursor material is calcined in an air atmosphere and then activated in a water vapor atmosphere to obtain the iron-manganese doped porous material.
2. The application according to claim 1, characterized in that, The alkaline solution in step S1 is a 0.2-0.5 M NaOH solution, the etching temperature is 50-65℃, and the etching time is 10-40 minutes; the porous support is zeolite, molecular sieve, or porous ceramic particles.
3. The application according to claim 1, characterized in that, In step S2, the manganese salt solution is a 5-50 mM manganese acetate or manganese nitrate solution, the immersion temperature is 60-80℃, and the immersion time is 0.5-3 hours; the permanganate solution is a 0.5-2 mM potassium permanganate solution, the oxidation treatment temperature is 40-70℃, and the treatment time is 10-60 minutes.
4. The application according to claim 1, characterized in that, The iron complex salt solution in step S3 is a 5-50 mM iron citrate solution, the immersion temperature is 80-90℃, and the immersion time is 0.5-3 hours; the reducing agent solution is a 5-20 mM ascorbic acid or glucose solution, and the treatment time is 10-60 minutes.
5. The application according to claim 1, characterized in that, In step S4, the ferrous salt solution is a 5-20 mM FeSO4 solution, the permanganate solution is a 0.2-1 mM KMnO4 solution, the immersion time is 5-10 minutes each time, and the number of alternating immersion cycles is 3-6 times; the drying temperature is 100-120℃.
6. The application according to claim 1, characterized in that, The calcination temperature in step S5 is 350-450℃, and the calcination time is 1.5-3 hours; the activation temperature is 120-200℃, and the activation time is 0.5-2 hours.
7. A method for aerobic composting using the iron-manganese-doped porous material according to any one of claims 1-6, characterized in that, Includes the following steps: S1. Pre-treat organic waste to control particle size ≤5 cm, moisture content 50%-60%, and C / N ratio 25-30; S2. Add the iron-manganese-doped porous material at 1.0-3.0 wt% of the total mass of the compost raw materials and mix evenly; S3. The mixture is intermittently aerated and turned for composting. The aeration rate is 0.05 L / (min·L), the aeration frequency is 10-20 min / h, the turning frequency is once every 2-3 days, and the high temperature period lasts for no less than 5 days.
8. The method according to claim 7, characterized in that, After composting, the iron-manganese-doped porous material can be recycled and regenerated. The regeneration method is air oxidation or rinsing with a low-concentration hydrogen peroxide solution, and the number of cycles is no less than 5.