title: Characterizing reactive oxygen generation and bacterial inactivation by a zerovalent iron-fullerene nano-composite device at neutral pH under UV-A illumination.
abstract: A nano-composite device composed of nano-scale zerovalent iron (ZVI) and C60 fullerene aggregates (ZVI/nC60) was produced via a rapid nucleation method. The device was conceived to deliver reactive oxygen species (ROS) generated by photosensitization and/or electron transfer to targeted contaminants, including waterborne pathogens under neutral pH conditions. Certain variations of the nano-composite were fabricated differing in the amounts of (1) ZVI (0.1mM and 2mM) but not nC60 (2.5mg-C/L), and (2) nC60 (0-25mg-C/L) but not ZVI (0.1mM). The generation of ROS by the ZVI/nC60 nano-composites and ZVI nanoparticles was quantified using organic probe compounds. 0.1mM ZVI/2.5mg-C/L C60 generated 3.74-fold higher O2(-) concentration and also resulted in an additional 2-log inactivation of Pseudomonas aeruginosa when compared to 0.1mM ZVI (3-log inactivation). 2mM ZVI/2.5mg-C/L nC60 showed negligible improvement over 2mM ZVI in terms of O2(-) generation or inactivation. Further, incremental amounts of nC60 in the range of 0-25mg-C/L in 0.1mM ZVI/nC60 led to increased O2(-) concentration, independent of UV-A. This study demonstrates that ZVI/nC60 device delivers (1) enhanced O2(-) with nC60 as a mediator for electron transfer, and (2) (1)O2 (only under UV-A illumination) at neutral pH conditions.
authors.affiliation: Center for the Environmental Implications of NanoTechnology, Duke University, Durham, NC 27708, USA; Environmental Engineering Department, Marmara University, Istanbul 34469, Turkey.
authors.forename: Esra
authors.initials: E
authors.lastname: Erdim
authors.affiliation: Center for the Environmental Implications of NanoTechnology, Duke University, Durham, NC 27708, USA; Department of Civil and Environmental Engineering, Duke University, Durham, NC 27708, USA.
authors.forename: Appala Raju
authors.initials: AR
authors.lastname: Badireddy
authors.affiliation: Department of Civil and Environmental Engineering, Duke University, Durham, NC 27708, USA; Department of Civil and Environmental Engineering, Duke University, Durham, NC 27708, USA. Electronic address: wiesner@duke.edu.
authors.forename: Mark R
authors.initials: MR
authors.lastname: Wiesner
mesh_terms: D037741:Fullerenes / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000737:chemistry; D053758:Nanoparticles / Q000737:chemistry*; D017319:Photosensitizing Agents / Q000737:chemistry*; D011550:Pseudomonas aeruginosa / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000737:chemistry*; D013481:Superoxides / Q000737:chemistry; D014466:Ultraviolet Rays
chemical_list: D037741:Fullerenes; D017319:Photosensitizing Agents; D017382:Reactive Oxygen Species; D013481:Superoxides; D007501:Iron; C069837:fullerene C60
keywords: Fullerene; Nano-composite; Nano-scale zerovalent iron; Photosensitization; Reactive oxygen species