Impact of Interactions between Metal Oxides to Redox Reactivity of Iron and Manganese Oxides

1236517 zhang了解环境中新兴污染物的命运对于评估其对生态系统的潜在风险至关重要。然而，通过简单的模型系统进行实验和建模，无法准确地获得复杂环境系统中污染物命运的定量估计。出于这个原因，该项目将研究包含二元氧化物混合物的复杂模型系统，以类似于土壤-水环境：铁（Fe）或锰（Mn）氧化物作为氧化还原活性氧化物，铝、硅或其他铁氧化物作为第二氧化物。主要目的是确定第二种金属氧化物的存在如何影响铁/锰氧化物的氧化还原活性。具体来说，将研究两种模型系统对八种有机污染物的氧化还原反应性：氧化环境中含有二氧化锰或针铁矿作为主要氧化剂，还原环境中含有可溶性铁离子，针铁矿作为主要还原剂。将进行实验和建模工作来研究上述系统中目标污染物的反应动力学。潜在的粒子相互作用将基于表面络合，表面沉淀，异质聚集和竞争吸附进行评估。这项研究首次研究了两种不同类型的金属氧化物之间的相互作用如何影响铁和锰氧化物的氧化还原活性。这项研究将产生对预测氧化还原活性土壤-水环境中新出现的污染物的命运至关重要的知识。该项目的智力价值基于：1)对二元氧化物混合物中相互作用的本质以及这些相互作用如何受到溶液化学（包括pH值、氧化物组成和离子强度）的影响的基本理解；2)对第二种金属氧化物在氧化和缺氧条件下如何影响Fe/Mn氧化物氧化还原行为的机理理解；3)定量模拟金属氧化物之间每种相互作用对第二种金属氧化物对Fe/Mn氧化物氧化还原活性的总体抑制作用的相对贡献。这项研究将为从事金属氧化物研究的水生化学家、环境工程师、地球化学家和微生物学家在土壤-水环境的活性或污染物去除方面创造一个新的知识体系。通过开发复杂的模型系统，该项目的结果可以使更准确的风险分析成为可能，最终可由公共卫生和环境机构用于污染物管制和环境清理。该项目还将有助于研究生、本科生和高中生的培训、指导和全面发展。其他计划的外联活动包括让代表性不足的少数民族和女学生（特别是来自女工程师协会）参与，为女高中生举办为期一周的夏季讲习班，在国家科学基金会水与环境技术中心的年度工业咨询委员会会议上向30多个工业伙伴广泛传播，将其纳入天普大学的环境课程，并在为来自费城地区的1000多名圣殿会员和3000多名工作专业人士提供服务的圣殿研讨会上发表演讲。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。

1236517ZhangUnderstanding the fate of emerging contaminants in the environment is critical for assessing their potential risks to ecological systems. Yet, quantitative estimates of contaminant fate in complex environmental systems cannot be accurately obtained through experimentation and modeling with simple model systems. For this reason, this project will investigate complex model systems containing binary oxide mixtures to resemble soil-water environments: iron (Fe) or manganese (Mn) oxides as the redox active oxides and aluminum, silicon or other iron oxides as the second oxides. The main objective is to determine how the presence of a second metal oxide affects the redox activity of Fe/Mn oxides. Specifically, two model systems will be examined for their redox reactivity with respect to eight organic contaminants: an oxidizing environment containing either manganese dioxide or goethite as the dominant oxidant and a reducing environment containing soluble ferrous ions in the presence of goethite as the dominant reductant. Experimental and modeling work will be carried out to study the reaction kinetics of the target contaminants in the above systems. Potential particle interactions will be evaluated based on surface complexation, surface precipitation, heteroaggregation, and competitive adsorption. This study is the first to examine how the interactions between two different types of metal oxides affect the redox activity of iron and manganese oxides. This research will generate knowledge that is critical for predicting the fate of emerging contaminants in redox active soil-water environments. The intellectual merit of this project is based on: 1) a fundamental understanding of the nature of interactions within binary oxide mixtures and how these interactions are affected by solution chemistry including pH, oxide composition, and ionic strength; 2) a mechanistic understanding of how a second metal oxide affects the redox behavior of Fe/Mn oxides under oxic and anoxic conditions; and 3) quantitative modeling of the relative contribution of each type of interaction between metal oxides to the overall inhibitory effect of a second metal oxide on the redox activity of Fe/Mn oxides.This study will create a new body of knowledge available to aquatic chemists, environmental engineers, geochemists and microbiologists working with metal oxides in terms of either the activity of soil-water environments or contaminant removal. By developing complex model systems, results of this project can enable a more accurate risk analysis which could eventually be used by public health and environmental agencies for contaminant regulation and environmental clean-up. This project will also contribute to training, mentoring and overall development of graduate, undergraduate and high school students. Other planned outreach activities include participation of underrepresented minority and female students (particularly from the Society of Women Engineers), one-week summer workshops for female high school students, broad dissemination to over 30 industrial partners at the annual industrial advisory board meetings for the NSF Water and Environmental Technology (WET) Center, integration into the environmental curriculum at the Temple University, and presentation at Temple seminars that serve 1000+ Temple members and 3000+ working professionals from the great Philadelphia area.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.