title: Effects of a nanoceria fuel additive on the physicochemical properties of diesel exhaust particles.
abstract: Nanoceria (i.e., CeO2nanoparticles) fuel additives have been used in Europe and elsewhere to improve fuel efficiency. Previously we have shown that the use of a commercial fuel additive Envirox™ in a diesel-powered electricity generator reduced emissions of diesel exhaust particle (DEP) mass and other pollutants. However, such additives are currently not permitted for use in on-road vehicles in North America, largely due to limited data on the potential health impact. In this study, we characterized a variety of physicochemical properties of DEPs emitted from the same engine. Our methods include novel techniques such as Raman spectrometry for analyzing particle surface structure and an assay for DEP oxidative potential. Results show that with increasing Envirox™ concentrations in the fuel (0×, 0.1×, 1×, and 10× of manufacturer recommended 0.5 mL Envirox™ per liter fuel), DEP sizes decreased from 194.6 ± 20.1 to 116.3 ± 14.8 nm; the zeta potential changed from -28.4 mV to -22.65 mV; DEP carbon content decreased from 91.8% to 79.4%; cerium and nitrogen contents increased from 0.3% to 6.5% and 0.2% to 0.6%, respectively; the ratio of organic carbon (OC) to elemental carbon (EC) increased from 22.9% to 38.7%; and the ratio of the disordered carbon structure to the ordered carbon structure (graphitized carbon) in DEPs decreased. Compared to DEPs emitted from 0×, 0.1×, and 1× fuels, DEPs from the 10× fuel had a lower oxidative potential likely due to the increased ceria content because pure ceria nanoparticles exhibited the lowest oxidative potential compared to all the DEPs. Since the physicochemical parameters tested here are among the determinants of particle toxicity, our findings imply that adding ceria nanoparticles into diesel may alter the toxicity of DEPs. The findings from the present study, hence, can help future studies that will examine the impact of nanoceria additives on DEP toxicities.
authors.affiliation: Nicholas School of the Environment, Duke Global Health Institute, Duke University, Durham, NC, USA. junfeng.zhang@duke.edu.
authors.forename: Junfeng Jim
authors.initials: JJ
authors.lastname: Zhang
authors.affiliation: Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ, USA.
authors.forename: Ki-Bum
authors.initials: KB
authors.lastname: Lee
authors.affiliation: Nicholas School of the Environment, Duke Global Health Institute, Duke University, Durham, NC, USA. junfeng.zhang@duke.edu.
authors.forename: Linchen
authors.initials: L
authors.lastname: He
authors.affiliation: National Heart and Lung Institute, Imperial College London, London, UK.
authors.forename: Joanna
authors.initials: J
authors.lastname: Seiffert
authors.affiliation: Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ, USA.
authors.forename: Prasad
authors.initials: P
authors.lastname: Subramaniam
authors.affiliation: Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ, USA.
authors.forename: Letao
authors.initials: L
authors.lastname: Yang
authors.affiliation: National Heart and Lung Institute, Imperial College London, London, UK.
authors.forename: Shu
authors.initials: S
authors.lastname: Chen
authors.affiliation: National Heart and Lung Institute, Imperial College London, London, UK.
authors.forename: Pierce
authors.initials: P
authors.lastname: Maguire
authors.affiliation: Department of Environmental Sciences, Rutgers University, Piscataway, NJ, USA.
authors.forename: Gediminas
authors.initials: G
authors.lastname: Mainelis
authors.affiliation: School of Public Health, Rutgers University, Piscataway, NJ, USA.
authors.forename: Stephan
authors.initials: S
authors.lastname: Schwander
authors.affiliation: National Heart and Lung Institute, Imperial College London, London, UK.
authors.forename: Teresa
authors.initials: T
authors.lastname: Tetley
authors.affiliation: National Heart and Lung Institute, Imperial College London, London, UK.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Porter
authors.affiliation: Department of Materials, London Centre for Nanotechnology, Imperial College London, London, UK.
authors.forename: Mary
authors.initials: M
authors.lastname: Ryan
authors.affiliation: Department of Materials, London Centre for Nanotechnology, Imperial College London, London, UK.
authors.forename: Milo
authors.initials: M
authors.lastname: Shaffer
authors.affiliation: Department of Materials, London Centre for Nanotechnology, Imperial College London, London, UK.
authors.forename: Sheng
authors.initials: S
authors.lastname: Hu
authors.affiliation: Nicholas School of the Environment, Duke Global Health Institute, Duke University, Durham, NC, USA. junfeng.zhang@duke.edu.
authors.forename: Jicheng
authors.initials: J
authors.lastname: Gong
authors.affiliation: National Heart and Lung Institute, Imperial College London, London, UK.
authors.forename: Kian Fan
authors.initials: KF
authors.lastname: Chung
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D002244:Carbon / Q000032:analysis; D002563:Cerium / Q000737:chemistry*; D005742:Gasoline; D053768:Metal Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis*; D001335:Vehicle Emissions / Q000032:analysis*
chemical_list: D000393:Air Pollutants; D005742:Gasoline; D052638:Particulate Matter; D001335:Vehicle Emissions; D002563:Cerium; C030583:ceric oxide; D002244:Carbon