【作者】 许伟；

【导师】 吴祖成；

【作者基本信息】 浙江大学 ， 环境工程， 2017， 博士

【摘要】 环境中的氨及其衍生物如尿素、氨基酸等是一类常见的含氮污染物。生物法处理含氮废水是一传统的方法、有一定的经济性,但周期长、受C/N比和浓度限制等缺点,且消耗大量能量。电化学方法直接提供电能达到氧化分解目的,可以有效地、快速处理,但是高昂的成本限制了电化学方法的大规模运用。事实上,含氮废水中含有化学能,在合适的催化剂作用下,尿素、氨基酸和氨可以发生氧化反应,产生氮气并释放电子。通过电化学体系氨和其衍生物转化为电能或氢能,这样在处理了污染物的同时回收了能源,即污染物的能源化处理。本论文组装了以含氮化合物为燃料的电对燃料电池,将储存在其中的电能直接予以提取。高效稳定的阳极催化剂是电化学体系的关键之一,研究制备了非贵金属Ni/C、NiCo/C、NiCu双金属和NiCu氢氧化物纳米线催化剂取代传统的易中毒的贵金属铂基阳极催化剂。利用电子显微镜、X射线衍射、X射线光电子能谱、电化学测试等手段对催化剂进行表征,构建了阴离子交换膜燃料电池体系,成功地以尿素(尿液)、氨基酸作为电子供体在阳极自发地发生氧化反应,并以氧气、六价铬作为电子受体在阴极进行还原反应,从而将蕴含的化学能直接转化为电能的同时降解污染物。尿素电池在Ni/C和NiCo/C阳极催化剂作用下分别获得了 1.4 mW cm-2和2.0 mW cm-2的最大功率密度。氨基酸电池在阳极催化剂Ni/C和NiCo/C作用下分别获得了 1.9 mW cm-2和3.0 mW cm-2的最大功率密度。在尿液-六价铬两种污染物组成的燃料电池中,得到了 3.4 W m-2的最大功率密度和1.3 V的开路电压,尿液中的TOC和TN去除率分别为79.2%和78.4%,同时阴极液中Cr(Ⅵ)的去除率达到了 93%。电化学表征证明NiCu双金属催化剂和NiCu氢氧化物纳米线催化剂相比于Ni和贵金属Pt基催化剂具有更好的催化活性和稳定性,有助于解决氨电氧化技术中阳极催化剂的问题。实验证明,非贵金属的纳米Ni基催化剂可以很好地作为尿素、氨基酸和氨电化学氧化反应的阳极催化剂,处理废水同时回收能源,这一方法有望成为污染物处理的一种新技术。此外,尿素、氨基酸和氨是储氢能源物质,可以利用富余的电能进行人工合成,再在需要时通过这一电化学体系产电,将是一个新型的化学储能途径。更多还原

【Abstract】 Urea,amino acids and ammonia,are common environmental polluents.Biological treatment of these N-cotaining pollutants is a cost effective method,but it has drawbacks such as long working time,C/N ratio and N concentration limitations.Electrochemical treatment can avoid above drawbacks.However,electrochemical treatment usually needs expensive electrode materials and vast electric power leading to high cost.In fact,urea,amino acids and ammonia all contain chemical energy,which can be used to generate electricity similar to hydrogen gas and methanol.Urea,amino acids and ammonia can be oxidized to nitrogen gas with electrons releasing spontaneously by using proper catalysts.In this way,N-containing wastewater is degraded with self-gernration of electricity via fuel cells,reducing the cost in electrochemical treatment.In this work,non-precious Ni-based nanomaterials were prepared as anode catalysts and characterized by XRD,XPS,SEM,TEM and electrochemical tests.Direct urea fuel cell(DUFC)and amino acids fuel cell(AAFC)are fabricated with Ni/C or NiCo/C catalysts.Results show that DUFC achieves a maximum power density of 1.4 mW cm-2 and 2.0 mW cm-2 with Ni/C and NiCo/C catalysts respectively.AAFC achieves a maximum power density of 1.9 mW cm-2 and 3.0 mW cm-2 with Ni/C and NiCo/C catalysts respectively.Besides,urine-Cr(VI)fuel cell is fabricated to degrade urine and Cr(VI)at the same time.The maximum power density reaches 3.4 W m-2 with open circuit voltage of 1.3 V.The removal efficiencies of total organic carbon and total nitrogen in urine are 79.2%and 78.4%,while the removal efficiency of Cr(VI)reaches 93%.Although Ni catalysts can be used as anode catalysts for electrooxidation of urea and amino acids,they are inactive toward amminoa acids.In order to solve this problem,novel NiCu bimetal catalyst and NiCu hydroxide nanowires catalyst are synthesized.Electrochemical tests show they have much better performance in the aspects of catalytic activity and stability than Ni and Pt based catalysts.更多还原