【作者】 张腾；

【导师】 徐龙君；

【作者基本信息】 重庆大学 ， 安全科学与工程， 2022， 硕士

【摘要】 随着社会的高速发展和资源的过度开发利用,环境安全问题在我国乃至世界范围内尤为突显,废水处理已成为当前环境安全问题的重点部分。其中,老龄垃圾渗滤液为垃圾填埋场产生的污染物,页岩气返排废水是页岩气开采过程中产生的废水,两者处理不当都会对环境产生较大的危害。传统污水处理工艺能耗大、处理费用高昂、资源化利用率不高,而微生物燃料电池（Microbial fuel cells,MFC）能够将有机污染物的化学能通过微生物催化反应转化为电能,可以做到在降解废水中有机物的同时产生电能。提高MFC性能的核心之一是制备出高效的电极材料,因此,本文以Co₃O₄为基础,通过Y分子筛复合、氢氟酸处理和MoS₂复合三种方式对Co₃O₄进行改性,以提高其催化性能,进而提升MFC的产电和污染物降解性能。采用X射线衍射光谱（XRD）、扫描电镜（SEM）、透射电镜（TEM）、X射线光电子能谱分析（XPS）、比表面积和孔径分析（BET）等测试手段对所制备催化材料的结构、微观形貌和比表面积等进行表征分析。将改性Co₃O₄催化剂涂敷到碳布上作为阳极,构建单室MFC处理老龄垃圾渗滤液和页岩气返排废水的混合废液,通过对电池的输出电压、功率密度、运行前后的化学需氧量（Chemical Oxygen Demand,COD）、氨氮（NH₃-N）等指标的测试,评估了催化材料对MFC产电性能和污染物降解效果的影响。通过浸渍-焙烧法制备出Co₃O₄/Y复合催化剂,通过电化学循环伏安测试和Tafel测试确定Co₃O₄占30%为最佳复合比例,其峰电流密度可达1.15 A/m²,Tafel交换电流密度为0.054 m A/cm²。微观形貌分析表明,Co₃O₄单样团聚成球状,而在Co₃O₄/Y中,Co₃O₄均匀分布于Na Y骨架表面,BET测试证明其比表面积的增大,暴露更多的活性位点,有利于催化反应的进行。将复合催化剂涂敷在碳布上作为阳极构建四组单室MFC,处理垃圾渗滤液和页岩气返排废水的混合废液,Co₃O₄/Y组MFC的产电性能最佳,最大稳定输出电压可达466 m V,最大功率密度为1140m W/m²,与空白碳布组MFC相比,产电性能提升较大。对COD和氨氮去除率最高可达33.74%和50.66%,表明所构建的MFC处理垃圾渗滤液和页岩气返排废水的混合废水可以实现产电并具有一定的污染物降解效果。利用水热-焙烧法制备出Co₃O₄/Y复合催化剂,再用氢氟酸溶液对样品做进一步改性,得到的最优样H-Co₃O₄/Y在电化学测试中峰电流密度可达6.45 A/m²,Tafel交换电流密度可达0.038 m A/cm²。阳极催化剂对MFC的产电性能具有较大的影响,H-Co₃O₄/Y组MFC的产电性能表现最佳,其最大稳定输出电压可达448 m V,而四组MFC对混合废液中COD的去除率差异较小,对氨氮的去除率可达40%以上。通过两步水热法成功制备出Co₃O₄/MoS₂复合催化材料,当MoS₂质量分数为20%时,Co₃O₄/MoS₂复合催化材料性能最佳,MoS₂的加入使复合催化剂的导电性和催化性能均有所提升。Co₃O₄/MoS₂复合催化材料中纳米棒状的Co₃O₄和薄片状的MoS₂相互交织叠加,Co₃O₄的团聚现象减弱。构建的四组单室MFC中,Co₃O₄/MoS₂组MFC表现出最佳的产电性能,其最大稳定输出电压可达539 m V,最大功率密度可达2221 m W/m²,负载有催化剂的MFC氨氮去除率相比于空白碳布MFC有10%左右的提升。更多还原

【Abstract】 With the rapid development of society and over-exploitation of resources,environmental safety issues are particularly serious in China and the world,and wastewater treatment has become a key part of current environmental safety issues.Aging landfill leachate is a pollutant generated from landfills,and shale gas flowback wastewater is generated during the shale gas extraction process,both of which can cause greater harm to the environment if not treated properly.Traditional wastewater treatment processes have high energy consumption,high treatment costs and low utilization of waste resources,while microbial fuel cells（MFC）can convert the chemical energy of organic contaminant into electricity through microbial catalytic reactions,which can generate electricity while degrading wastewater.The preparation of efficient electrode materials is the key to improve the performance of MFC.Therefore,in this paper,Co₃O₄ is modified by Y molecular sieve,hydrofluoric acid and MoS₂ to improve its catalytic performance,and then enhance the electricity production and pollutant degradation performance of MFC.The structure,microscopic morphology and specific surface area of the prepared catalytic materials were characterized and analyzed by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,X-ray photoelectron spectroscopy（XPS）and specific surface area and pore size analysis（BET）.The modified Co₃O₄ catalyst was coated onto carbon cloth as an anode,and the single-chamber MFC was constructed to treat the mixed wastewater of aging landfill leachate and shale gas flowback wastewater.The effect of catalytic materials on the MFC power production and pollutant degradation performance were evaluated by testing the output voltage,power density,chemical oxygen demand（COD）,ammonia nitrogen（NH₃-N）and other indicator of the cell.The Co₃O₄/Y composite anode catalyst was prepared by the impregnation-roasting method.The electrochemical cyclic voltammetry test and Tafel test determined that 30%was the optimal composite ratio,and its peak current density could reach 1.15 A/m² and Tafel exchange current density was 0.054 m A/cm².Microscopic morphological analysis showed that Co₃O₄ samples agglomerated into spheres,while in Co₃O₄/Y,Co₃O₄ was uniformly distributed on the surface of the Na Y skeleton.BET tests demonstrated the increase in the specific surface area of Co₃O₄/Y,which could expose more active sites and facilitate the catalytic reaction.The catalysts were coated on carbon cloth as the anode,and four single-chamber MFCs were constructed to treat the mixed wastewater of aging landfill leachate and shale gas flowback wastewater.The MFC of Co₃O₄/Y showed the best power production performance with the maximum stable output voltage of 466 m V and the maximum power density of 1140 m W/m².Compared with the MFC of blank carbon cloth,the power production performance was greatly improved.The maximum removal rates of COD and ammonia nitrogen were up to 33.74%and 50.66%,indicating that the constructed MFC can produce electricity and have certain pollutant degradation effect in treating the mixed wastewater of aging landfill leachate and shale gas flowback wastewater.The Co₃O₄/Y anode catalyst was prepared by hydrothermal-roasting method,and then the samples were further modified by hydrofluoric acid solution.The optimal sample H-Co3O4/Y showed peak current density up to 6.45 A/m²and Tafel exchange current density up to 0.038 m A/cm²in the electrochemical test.The anode catalyst has a large influence on the electricity production performance of MFC,and the MFC of H-Co₃O₄/Y has the best performance,and its maximum stable output voltage can reach448m V.The removal rate of COD in mixed wastewater was less different among the four MFC groups,and the removal rate of ammonia nitrogen could reach more than40%.The Co₃O₄/MoS₂ composite catalytic materials were successfully prepared by a two-step hydrothermal method.The best performance of the Co₃O₄/MoS₂ composite catalytic material was achieved when the mass fraction of MoS₂ was 20%,and the addition of MoS₂ enhanced both the electrical conductivity and catalytic performance of the composite catalyst.In Co₃O₄/MoS₂ composite catalytic material,nanorod-like Co₃O₄ and lamellar MoS₂ interweaved and stacked each other,and the agglomeration of Co₃O₄ is weakened.Among the four groups of single-chamber MFCs constructed,the MFC of Co₃O₄/MoS₂ showed the best power production performance with the maximum stable output voltage up to 539 m V and the maximum power density up to2221 m W/m².And the ammonia nitrogen removal rate of the MFCs loaded with catalysts was improved by about 10%compared with the blank carbon cloth MFC.更多还原