Journal of Hazardous Materials 283 (2015) 80–88 Contents lists available at ScienceDirect Journal of Hazardous Materials jo ur nal ho me p ag e: www.elsevier.com/locate/jhazmat Characterizing reactive oxygen generation and bacterial inactivation by a zerovalent iron-fullerene nano-composite device at neutral pH under UV-A illumination Esra Erdim a,b , Appala Raju Badireddy a,c , Mark R. Wiesner a,c,∗ a Center for the Environmental Implications of NanoTechnology, Duke University, Durham, NC 27708, USA b Environmental Engineering Department, Marmara University, Istanbul 34469, Turkey c Department of Civil and Environmental Engineering, Duke University, Durham, NC 27708, USA h i g h l i g h t s • We synthesized a novel ZVI/nC 60 nano-composite device for multi-ROS generation. • O 2 • - (UV-A independent) and 1 O 2 (UV-A dependent) are generated at neutral pH. • At low Fe concentration, ZVI/nC 60 device is a better ROS generator than ZVI alone. • C 60 mediates electron transfer from ZVI surface to dissolved O 2 to produce O 2 • - . • Bacteria are rapidly inactivated by O 2 • - even at low ZVI/nC 60 ratio. a r t i c l e i n f o Article history: Received 18 February 2014 Received in revised form 16 July 2014 Accepted 13 August 2014 Available online 16 September 2014 Keywords: Nano-scale zerovalent iron Fullerene Nano-composite Reactive oxygen species Photosensitization a b s t r a c t A nano-composite device composed of nano-scale zerovalent iron (ZVI) and C 60 fullerene aggregates (ZVI/nC 60 ) 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 (0.1 mM and 2 mM) but not nC 60 (2.5 mg-C/L), and (2) nC 60 (0–25 mg-C/L) but not ZVI (0.1 mM). The generation of ROS by the ZVI/nC 60 nano-composites and ZVI nanoparticles was quantified using organic probe compounds. 0.1 mM ZVI/2.5 mg-C/L C 60 generated 3.74-fold higher O 2 •- concentration and also resulted in an additional 2-log inactivation of Pseudomonas aeruginosa when compared to 0.1 mM ZVI (3-log inactivation). 2 mM ZVI/2.5 mg-C/L nC 60 showed neg- ligible improvement over 2 mM ZVI in terms of O 2 •- generation or inactivation. Further, incremental amounts of nC 60 in the range of 0–25 mg-C/L in 0.1 mM ZVI/nC 60 led to increased O 2 •- concentration, independent of UV-A. This study demonstrates that ZVI/nC 60 device delivers (1) enhanced O 2 •- with nC 60 as a mediator for electron transfer, and (2) 1 O 2 (only under UV-A illumination) at neutral pH conditions. © 2014 Elsevier B.V. All rights reserved. 1. Introduction Previous investigators have observed that the fullerene C 60 is an efficient electron shuttle with the capability to accept up to six electrons from a donor molecule [1,2]. The photochemical and photophysical properties of C 60 have been well studied and it has been shown that the C 60 when subjected to photosensitization ∗ Corresponding author at: Department of Civil and Environmental Engineering, Duke University, Durham, NC 27708, USA. Tel.: +1 919 660 5292; fax: +1 919 660 5219. E-mail address: wiesner@duke.edu (M.R. Wiesner). transforms to an excited state ( 1 C 60 * and 3 C 60 *), which may pro- duce 1 O 2 via energy transfer or O 2 •- via electron transfer to oxygen [3–6]. The O 2 •- generation occurs through the formation of C 60 •- by photoexcited C 60 in the presence of an electron donor [7]. Zero- valent iron nanoparticles (ZVI NPs) have been observed to induce both reductive and oxidative reactions [8]. In the absence of oxygen, some contaminants are degraded by ZVI through direct electron transfer reactions (e.g., reductive dehalogenation of chlorinated solvents) [9–13], whereas under oxygenated conditions a variety of recalcitrant contaminants (e.g., pesticides, dyes, and aromatic com- pounds) may be oxidized by reactive oxygen species (ROS) that are by-products of ZVI NP oxidation [14–19]. Also, several studies have reported on the antimicrobial activity of iron-based nanoparticles http://dx.doi.org/10.1016/j.jhazmat.2014.08.049 0304-3894/© 2014 Elsevier B.V. All rights reserved.