Photochemical Transformations of Pollutants: Nitropyrene

污染物的光化学转化：硝基芘

• 批准号: 6766325
• 负责人: RAFAEL ARCE
• 金额: $ 7.65万
• 依托单位: UNIVERSITY OF PUERTO RICO RIO PIEDRAS
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-01 至 2008-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6766325
• 关键词: adsorption; aerosols; air pollution; biotransformation; carcinogens; chemical property; electron spin resonance spectroscopy; hazardous substances; intermolecular interaction; laser spectrometry; mutagens; nitrogen compounds; particle; photochemistry; physical property; pyrenes; solvents

1-Nitropyrene, a well known mutagenic and highly possible carcinogenic polycyclic aromatic hydrocarbon (PAH), is the most abundant nitrated PAH emitted in diesel engine exhaust and also found in coal combustion fly ash, cooked meat products and kerosene heaters emissions. It has been found at concentrations in the pg/m3 range in the air over urban and suburban areas and thus it has potential for human exposure through inhalation. The transformations in the atmosphere of these ubiquitous pollutants is still debated and a possible environmental fate for nitroPAHs is through their photodecomposition on particulate matter. Although some photodegradation rates and products have been determined in solution studies no reactive intermediates have been characterized to support the proposed mechanisms. Similar studies on these molecules adsorbed on substrates, which resemble their state on the environment, have been much more limited. In this work we are proposing to utilize techniques, we have already developed in our laboratory, to study the photochemical transformation mechanisms of nitropyrenes adsorbed into models of atmospheric aerosols in order to provide some understanding of the fate of these contaminants in the atmosphere. As we have found with PAHs, phototransformations at the solid/air interface can have a significant impact in controlling their residence time in the environment and are thus important in the evaluation of the potential risks of these contaminants, as well as in the possible design of systems for their removal. In order to understand the phototransformation mechanism of adsorbed nitropyrenes we will: (1) examine the interactions of the adsorbed molecules with the different substrates and establish the nature of the participating excited states by absorption and fluorescence techniques, (2) determine relative photodegradation rates, (3) identify intermediate species and triplet states by time resolved diffuse reflectance laser spectroscopy and electron spin resonance and (4) identify the stable products and compare them with those found in the solution photochemistry. A fundamental aim of this proposal is to study the effect of some chemical and physical properties of the adsorbent such as composition, water content, presence of coadsorbed gases, average pore diameter and surface coverage on the photophysical and photochemical processes of the adsorbed nitropyrenes. Also, the resulting excited states and reactive intermediates from the laser irradiation in polar and non polar solvents that mimic the aerosol will be characterized by laser flash transient spectroscopy. The accomplishment of this last aim is of most importance since nitroPAHs can be also found in the organic liquid like-core of combustion aerosols.

1-硝基吡啶是一种众所周知的诱变和较大可能的致癌多环芳烃（PAH），是在柴油发动机排气中排放的最丰富的硝化PAH，也发现在煤炭燃烧粉煤灰，煮熟的肉类产品和煤油加热器中。它在城市和郊区的空气中的PG/M3范围内发现了它，因此它具有通过吸入的人类暴露的潜力。这些普遍存在的污染物大气中的转变仍在争论中，并且可能是环境 亚硝化物的命运是通过其对颗粒物质的光电分解。尽管在解决方案研究中已经确定了一些光降解速率和产物，但尚未将反应性中间体表征以支持所提出的机制。对这些分子吸附在底物上的类似研究（类似​​于其在环境上的状态）受到了更大的限制。 在这项工作中，我们提议利用技术，我们已经在实验室中开发了，以研究硝化物的光化学转化机制吸附到大气气溶胶模型中，以便对这些污染物在大气中的命运有所了解。正如我们在PAHS中发现的那样，固体/空气界面处的光转化在控制环境中的停留时间可能会产生重大影响，因此对于评估这些污染物的潜在风险以及可能设计的可能设计很重要拆除的系统。为了了解吸附的硝化物的光转化机制，我们将：（1）检查吸附分子与不同底物的相互作用，并通过吸收和荧光技术来确定参与激发态的性质，（2）确定相对光降解率，相对光降解率，，，相对光降解率，，相对光降解率，，相对光降解率，，相对光降解率（3）按时间解决的时间识别中间物种和三重 扩散反射率激光光谱和电子自旋共振，（4）识别稳定产物并将其与溶液光化学中的产品进行比较。该提案的一个基本目的是研究吸附剂的某些化学和物理特性的影响，例如成分，水含量，辅助吸附气体的存在，平均孔径和表面覆盖率对吸附氮的光学和光化学过程的影响。同样，产生的激发态和反应性中间体来自极性和非极性溶剂中模仿气溶胶的激光照射，以激光闪光瞬态光谱法的特征。最后目标的实现最为重要，因为在燃烧气溶胶的有机液体中也可以找到亚硝化物。