论文中文题名: | MOFs/PDMS海绵复合材料的制备及其在好氧堆肥中的应用 |
姓名: | |
学号: | 21213065001 |
保密级别: | 公开 |
论文语种: | chi |
学科代码: | 081701 |
学科名称: | 工学 - 化学工程与技术 - 化学工程 |
学生类型: | 硕士 |
学位级别: | 工学硕士 |
学位年度: | 2021 |
培养单位: | 西安科技大学 |
院系: | |
专业: | |
研究方向: | 好氧堆肥臭气减排技术 |
第一导师姓名: | |
第一导师单位: | |
论文提交日期: | 2024-06-17 |
论文答辩日期: | 2024-06-03 |
论文外文题名: | Preparation of MOFs/PDMS sponge composite and application in compost |
论文中文关键词: | |
论文外文关键词: | MOFs ; composites ; adsorption property ; ammonia abatement ; electric field composting. |
论文中文摘要: |
随着农业和养殖业的专业化、规模化,大量畜禽粪便产生于养殖场中,给环境和人体健康造成了严重危害。好氧堆肥技术,作为一种能够实现有机废弃物无害化、资源化处理的先进方法,近年来备受瞩目。而电场辅助好氧堆肥技术 (即电场堆肥) 更是被证实为提升好氧堆肥过程无害化程度和效率的有效手段。然而,堆肥过程中往往伴随着大量的氮素损失,这不仅加剧了环境负担,还影响了好氧堆肥产品的整体质量。因此,如何在实现无害化处理的同时,减少氮素损失,提高堆肥效率,成为了当前亟待解决的问题。金属—有机骨架化合物 (MOFs) 材料以其出色的强吸附性能、大比表面积和高催化性能,为解决好氧堆肥过程中的气体排放和有毒有害物质分解问题提供了有效途径。此外,将具有良好力学性能和化学稳定性的聚合物基体与MOFs材料进行复合,不仅能够进一步提升MOFs材料的性能,还有助于延长其使用寿命。然而目前MOFs及其复合材料在好氧堆肥过程中的应用并未有太多的研究。因此,本研究致力于解决好氧堆肥过程中氮素损失问题,以操作简单效果明显的添加剂制备为研究目标,设计并开发一种能够有效降低堆肥过程中氨气排放新型的MOFs/聚二甲基硅氧烷 (PDMS) 海绵复合材料,并进行电场堆肥实验,旨在探究新型添加剂材料的效果及作用机理。研究的主要内容包括以下3部分: (1) 采用均苯三甲酸和二甲基咪唑为有机配体,锌为金属中心,分别成功制备了两种材料1,3,5-均三苯羧酸锌 (ZnBTC) 和2-甲基咪唑锌 (ZIF-8)。其中ZnBTC (11.37 mmol/g) 对NH3的吸收量高于ZIF-8 (1.26 mmol/g),ZnBTC在堆肥气体模拟环境中仍具有明显的氨气的吸附效果,而ZIF-8在堆肥气体模拟环境中基本没有吸附效果,这表明ZnBTC有助于减少堆肥过程中氨气带来的环境污染。理论计算结果表明,ZnBTC比ZIF-8具有更高的吸附能力,这与实验结果充分吻合。以上结果表明以均苯三甲酸为配体制备的MOFs材料在堆肥模拟环境中更具竞争力,因此在后续的研究中选择以均苯三甲酸为有机配体材料。 (2) 采用均苯三甲酸为有机配体成功制备了1,3,5-均三苯羧酸铁 (FeBTC)、1,3,5-均三苯羧酸锌 (ZnBTC)、1,3,5-均三苯羧酸铜 (CuBTC)三种MOFs材料。结果表明三种MOFs材料均表现出较高的氨吸附量。为了进一步深入了解其吸附机制,利用分子动力学模型 (DFT) 进行了分析。结果表明,CuBTC和ZnBTC因其高极性、强大的协调能力和简洁的结构特点,使得NH₃能够以直线形式与之结合。相对而言,FeBTC由于其结构稳定性较高,不易受到外界冲击。因此,FeBTC的金属位点与NH₃之间的键更稳定。此外,FeBTC极大的比表面积和良好的生物活性,更有利于堆肥过程的进行。因此选择了PDMS海绵进行负载,成功制备了FeBTC/PDMS海绵复合材料。 (3) 分别采用不同添加量的PDMS海绵和FeBTC/PDMS海绵复合材料进行电场堆肥实验。实验结果表明FeBTC/PDMS海绵具有良好的氨气减排效果,其中3% FeBTC/PDMS具有最佳的效果。相较于CK,3% FeBTC/PDMS减少了56.81%的NH3排放量,延长了5天的高温期持续时间。这可能是由于FeBTC/PDMS加入提高了堆肥过程中的氮转化微生物的活性,促进了铵态氮的转化,减少了氨气的挥发。此外,FeBTC/PDMS的施加并未对堆肥过程中微生物产生明显的毒害作用,堆肥过程中微生物多样性及活性均未受到显著的抑制。同时,FeBTC/PDMS还可有效促进堆肥过程中复杂有机质降解相关微生物的活性,促进了堆肥无害化及腐殖化过程的进行。 综上所述,本文设计了一种针对电场堆肥过程中氨气排放问题的FeBTC/PDMS新型添加剂,同时阐述了其作用机理。本研究为好氧堆肥氨气减排添加剂提供了新的研究思路和数据支撑。 |
论文外文摘要: |
The specialization and scale of the agriculture and breeding industry result in a significant production of livestock and poultry manure on farms, which poses serious environmental and health risks. In recent years, aerobic composting technology has gained considerable attention as an advanced method for achieving the harmless and resourceful treatment of organic waste. Electric field-assisted aerobic composting technology has been proven to be an effective approach in enhancing the degree of harmlessness and efficiency during the aerobic composting process. The composting process, however, often leads to significant nitrogen loss, which not only exacerbates the environmental burden but also impacts the overall quality of aerobic compost products. Therefore, finding ways to minimize nitrogen loss and enhance composting efficiency while achieving safe treatment has become an urgent issue that needs to be addressed. Metal-Organic Framework compounds (MOFs) offer an effective solution to address the challenges of gas emission and decomposition of toxic substances during aerobic composting, owing to their exceptional adsorption properties, large specific surface area, and high catalytic performance. Moreover, incorporating MOFs into a polymer matrix with excellent mechanical properties and chemical stability not only enhances the performance of MOFs but also extends their lifespan. However, there is limited research on the application of MOFs and their composites in aerobic composting. Therefore, this study aims to tackle the issue of nitrogen loss in aerobic composting by developing additives that are easy to use yet highly effective. Specifically, design a novel composite material consisting of MOFs/polydimethylsiloxane (PDMS) sponge that can significantly reduce NH3 emissions during composting processes. Additionally, conduct electric field-assisted composting experiments to investigate the effects and mechanisms of these new additive materials. The main content from this study are as follows: (1) The materials ZnBTC and ZIF-8 were successfully synthesized using trimeric acid and dimethylimidazole as organic ligands, with zinc serving as the metal centers. The NH3 absorption capacity of ZnBTC (11.37 mmol/g) was found to be higher than that of ZIF-8 (1.26 mmol/g). In a simulated compost gas environment, ZnBTC exhibited significant adsorption effect on ammonia gas, while ZIF-8 showed minimal adsorption effect. This indicates that the use of ZnBTC can effectively mitigate environmental pollution caused by ammonia during composting processes. Theoretical results also confirmed that ZnBTC has superior adsorption capacity compared to ZIF-8, which aligns well with the experimental findings. These results highlight the competitive advantage of MOFs prepared using trimeric acid as the coordination system in composting simulation environments, thus justifying its selection as the organic ligand material for subsequent studies. (2) FeBTC, ZnBTC, and CuBTC were synthesized using trimeric acid as the organic ligands. The experimental results demonstrated that all three MOFs exhibited enhanced ammonia adsorption capacity. To gain further insights into the adsorption mechanism, molecular dynamics simulations (DFT) were employed for analysis. The simulation results revealed that CuBTC and ZnBTC can form a linear arrangement due to their high polarity, strong coordination abilities, and compact structures. In contrast, FeBTC displayed remarkable resistance to external perturbations owing to its exceptional structural stability. Consequently, the bond between the metal site of FeBTC and NH3 was found to be more stable. Moreover, the large specific surface area and excellent biocompatibility of FeBTC facilitated the composting process effectively. Therefore, PDMS sponge was selected as a carrier material for loading FeBTC/PDMS composite successfully. (3) The electric field composting experiment was conducted using PDMS sponge and FeBTC/PDMS sponge composite with varying addition amounts, respectively. The experimental results demonstrate that the inclusion of 3% FeBTC/PDMS exhibits a significant reduction in NH3 emissions by 56.81% and prolonged the duration of high temperature period over 5 days. This can be attributed to the enhanced activity of nitrogen-converting microorganisms facilitated by FeBTC/PDMS, which promotes ammonium nitrogen conversion and reduces ammonia volatilization. Furthermore, during the composting process, no significant toxic effects on microorganisms were observed upon application of FeBTC/PDMS; microbial diversity and activity remained unaffected throughout composting. Additionally, FeBTC/PDMS effectively enhances the activity of microorganisms involved in complex organic matter degradation during composting while promoting a harmless and humification process. In summary, this paper presents the development of a novel FeBTC/PDMS additive for mitigating ammonia emissions during electric field composting and elucidates its underlying mechanism of action. This study offers a fresh research perspective and provides empirical evidence supporting the efficacy of aerobic compost additives in reducing ammonia emissions. |
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中图分类号: | TQ440.22 |
开放日期: | 2024-06-17 |