title: Impacts of a nanosized ceria additive on diesel engine emissions of particulate and gaseous pollutants.
abstract: Fuel additives incorporating nanosized ceria have been increasingly used in diesel engines as combustion promoters. However, few studies have assessed the impact of these nanotechnology-based additives on pollutant emissions. Here, we systematically compare emission rates of particulate and gaseous pollutants from a single-cylinder, four-cycle diesel engine using fuel mixes containing nanoceria of varying concentrations. The test fuels were made by adding different amounts of a commercial fuel additive Envirox into an ultralow-sulfur diesel fuel at 0 (base fuel), 0.1-, 1-, and 10-fold the manufacturer-recommended concentration of 0.5 mL Envirox per liter of fuel. The addition of Envirox resulted in ceria-concentration-dependent emission reductions of CO2, CO, total particulate mass, formaldehyde, acetaldehyde, acrolein, and several polycyclic aromatic hydrocarbons. These reductions at the manufacturer-recommended doping concentration, however, were accompanied by a substantial increase of certain other air pollutants, specifically the number of ultrafine particles (+32%), NO(x) (+9.3%), and the particle-phase benzo[a]pyrene toxic equivalence quotient (+35%). Increasing fuel ceria concentrations also led to decreases in the size of emitted particles. Given health concerns related to ultrafine particles and NO(x), our findings call for additional studies to further evaluate health risks associated with the use of nanoceria additives in various engines under various operating conditions.
authors.affiliation: Department of Preventive Medicine, Keck School of Medicine, University of Southern California , 2001 North Soto Street, Los Angeles, California 90089, United States.
authors.forename: Junfeng
authors.initials: J
authors.lastname: Zhang
authors.forename: Yevgen
authors.initials: Y
authors.lastname: Nazarenko
authors.forename: Lin
authors.initials: L
authors.lastname: Zhang
authors.forename: Leonardo
authors.initials: L
authors.lastname: Calderon
authors.forename: Ki-Bum
authors.initials: KB
authors.lastname: Lee
authors.forename: Eric
authors.initials: E
authors.lastname: Garfunkel
authors.forename: Stephan
authors.initials: S
authors.lastname: Schwander
authors.forename: Teresa D
authors.initials: TD
authors.lastname: Tetley
authors.forename: Kian Fan
authors.initials: KF
authors.lastname: Chung
authors.forename: Alexandra E
authors.initials: AE
authors.lastname: Porter
authors.forename: Mary
authors.initials: M
authors.lastname: Ryan
authors.forename: Howard
authors.initials: H
authors.lastname: Kipen
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Lioy
authors.forename: Gediminas
authors.initials: G
authors.lastname: Mainelis
mesh_terms: D000336:Aerosols / Q000737:chemistry; D000393:Air Pollutants / Q000032:analysis*; D000447:Aldehydes / Q000032:analysis; D002245:Carbon Dioxide / Q000032:analysis; D002248:Carbon Monoxide / Q000032:analysis; D002563:Cerium / Q000737:chemistry*; D005740:Gases / Q000032:analysis*; D005742:Gasoline / Q000032:analysis*; D053758:Nanoparticles / Q000737:chemistry*; D009589:Nitrogen Oxides / Q000032:analysis; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis*; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis; D001335:Vehicle Emissions / Q000032:analysis*
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D000447:Aldehydes; D005740:Gases; D005742:Gasoline; D009589:Nitrogen Oxides; D052638:Particulate Matter; D011084:Polycyclic Aromatic Hydrocarbons; D001335:Vehicle Emissions; D002245:Carbon Dioxide; D002563:Cerium; C030583:ceric oxide; D002248:Carbon Monoxide