RUI: Adsorption and Surface Mediated Photo-Degradation Rate of Contaminants on Colloidal Natural Organic Matter

在化学学部环境化学科学项目的支持下，波尔州立大学Mahamud Subir博士和他的学生探索了天然有机物质（NOM）对新兴污染物（ECs）的运输和命运的影响。ECs，如药物和内分泌干扰物，通常在水生环境中检测到。NOM是悬浮在环境水体中的由碳基分子组成的颗粒。NOM在水体污染物的分布和转化中起作用，但具体作用方式和作用程度尚不清楚。本研究的重点是寻找粒径和表面成分对有机污染物的吸收和光化学分解的影响。这些项目为本科生提供了一个独特的动手实验的机会。这项研究创造了有关污染物分子与NOM结合强度的信息，以及由NOM表面介导的反应速率。这些发现有助于解释ec对我们的生态系统和健康的影响。本研究在纳米化学、表面化学和环境化学领域使用了传统和先进的激光光谱工具。二次谐波产生（SHG）和其他分析技术从有机污染物的体溶液光化学中分离出表面效应。该项目利用不同成分的腐殖质开发模型胶体NOM。测量了各种ec与模型NOM表面的结合亲和力。测定了化学吸附和物理吸附分子在无机-水界面的光解速率。此外，该项目还研究了NOM尺寸、溶液酸度和活性羟基自由基的存在对感兴趣的过程的影响。这些结果有望产生广泛的吸附平衡和光动力学参数目录。它们还提供了对特定EC-NOM表面相互作用性质的基本见解。这些知识可以潜在地帮助开发补救方法。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With support from the Environmental Chemical Sciences Program of the Chemistry Division, Dr. Mahamud Subir and his students at Ball State University explore the influence of Natural Organic Matter (NOM) on the transport and fate of emerging contaminants (ECs). ECs, such as pharmaceuticals and endocrine disruptors, are commonly detected in aquatic environments. NOM are particles suspended in environmental waters that consist of carbon-based molecules. NOM plays a role in aquatic pollutant distribution and transformation, but exactly how and to what extent remains unclear. This study focuses on finding the effect of NOM particle size and surface constituents on the uptake and photochemical breakdown of organic contaminants. The projects provide undergraduate students with a unique opportunity to perform hands-on experiments. The study creates information about binding strength of the contaminant molecules and NOM, and the rates of reactions that are mediated by the NOM surfaces. These findings help to explain the impact of ECs on our ecosystem and our health. This study uses both traditional and advanced laser spectroscopic tools in the areas of nano-, surface, and environmental chemistry. Second Harmonic Generation (SHG) and other analysis techniques isolate the surface effect from the bulk solution phase photochemistry of organic pollutants. The project develops model colloidal NOM using humic substances of distinct composition. The binding affinities of various ECs to the model NOM surfaces are measured. The rate of photolysis of both chemi- and physi-sorbed molecules at the NOM-aqueous interface is determined. In addition, the project investigates the influence of NOM size, solution acidity, and presence of reactive hydroxyl radicals on the processes of interest. These results are expected to yield an extensive catalogue of adsorption equilibrium and photo-kinetic parameters. They also provide fundamental insight into the nature of specific EC-NOM surface interactions. This knowledge can potentially assist in developing remediation methodologies.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.