Collaborative Research: Adsorption and Photochemical Transformations of Arsenic and Selenium Species by Natural Organic Matter-Coated Magnetic Nano-sized Iron Oxide Particles

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This award is supported jointly by the Chemistry Division's Environmental Chemical Sciences Program and the Environmental Engineering Program in the Division of Chemical, Bioengineering, Environmental, and Transport Systems. The collaborative study involves Professors Kevin E. O'Shea and Yong Cai from Florida International University and Professor Dionysios D. Dionysiou from University of Cincinnati. Together with their students, the faculty members seek to develop an environmentally-friendly approach to purifying water. Water contamination by highly toxic arsenic (As) and selenium (Se) is a serious threat to the environment. This has affected the health of hundreds of millions of humans globally. The approach is to coat magnetic iron oxide nanoparticles with natural organic matter (NOM). The coated nanoparticles can strongly bind arsenic and selenium and can convert them to less toxic forms upon solar irradiation. The magnetic nanoparticles carrying the arsenic and selenium are later removed from the contaminated water with a magnet. Overall, the research activities are expected to strengthen co-operation among the local community, educational institutes, and investigators. Thebroader societal impacts of this research include enhancing sustainable development. The knowledge obtained from these studies guides the development of new water treatment methodologies using environmentally-friendly materials. Application of these insights may accelerate the implementation of related technologies in addressing environmental problems, as well as advance the understanding of the interaction of natural organic matter and metals to determine their fate, transport and bioavailability. The research plan emphasizes participation of persons from underrepresented groups. It also includes a high school outreach program with local schools to educate the students on water quality and water contamination issues.The project seeks to develop a fundamental understanding of the molecular interactions of As and Se species with fractionated NOM and the subsequent NOM-photosensitized redox transformations of As and Se. Specific trapping or quenching agents are used to study the roles of individual reactive oxygen species, electron transfer and energy transfer processes in the NOM photosensitized transformations. These fundamental studies guide the selection of the most promising NOM fractions for grafting onto the surface of different sized magnetic iron oxide nanoparticles for the process of interest. The research is expected to aid in the development of strategies for optimizing removal and conversion of toxic metals. Such a process is is critical to water reuse and treatment.