Photochemical Fate of Manufactured Carbon Nanomaterials in the Aquatic Environment

EPA Grant Number: R833340
Title: Photochemical Fate of Manufactured Carbon Nanomaterials in the Aquatic Environment
Investigators: Jafvert, Chad T. , Hua, Inez
Institution: Purdue University
EPA Project Officer: Shapiro, Paul
Project Period: May 10, 2007 through April 30, 2009
Project Amount: $199,900
RFA: Exploratory Research: Nanotechnology Research Grants Investigating Environmental and Human Health Effects of Manufactured Nanomaterials: a Joint Research Solicitation-EPA, NSF, NIOSH, NIEHS (2006) RFA Text |  Recipients Lists
Research Category: Health , Safer Chemicals , Health Effects , Nanotechnology

Objective:

For many organic chemicals, photodegradation is a significant environmental fate processes, and information regarding the rates and products of these reactions are therefore important in overall risk assessment analysis. The overall objective of the proposed research is to investigate photochemical transformation of buckminsterfullerene (C60) and single wall carbon nanotubes (SWCNT) under conditions of environmental relevance. Due to the strong light absorbance of these materials within the solar spectrum, photochemical transformation in the environment may lead to potentially more water soluble and easily bioaccumulative products. The three sub-objectives are: 1) to measure photochemical transformation rates and products of C60 solid films hydrated with aqueous solutions under solar irradiation; 2) to measure solar photochemical transformation of C60 in aqueous humic acid solutions and as clusters in aqueous solution; and 3) to extend these measurements to include the photochemical transformation of single walled carbon nanotubes (SWCNTs) under similar conditions.

Approach:

Natural sunlight (West Lafayette, IN, 40° 26’ N, 86° 55’ W) and solar-simulated light (λ = 350 ± 50 nm black light phosphor lamps) will be used as the light sources for all photochemical experiments. In most experiments solutions or cluster suspensions of C60 or SWCNTs will be irradiated and the loss rate, product formation rate(s), and spectroscopic and microscopic characteristics of the solutions will be monitored. Initial experiments will examine photodegradation of C60 and SWCNT plated onto test tube walls, hydrated with water containing various naturally occurring substances (i.e., carbonates, humic acids, O2), with later experiments examining photodegradation of aqueous clusters in the presence of these same substances. Decay and product formation will be followed by HPLC, microscopy (SEM, HRTEM at the Pacific Northwest National Laboratory), and spectroscopic methods.

Expected Results:

Photochemical experiments with C60 and the more complex SWCNTs in environmentally relevant water-containing solutions, and the identification of reaction products in such experiments, will help assess the potential hazards of these materials when they are released into the aquatic environment.

Supplemental Keywords:

nanotechnology, environmental chemistry, water, aquatic, organics,, RFA, Health, Scientific Discipline, Health Risk Assessment, Aquatic Ecosystem, Risk Assessments, marine ecosystem, biological pathways, nanotechnology, bioavailability, genetic analysis, carbon fullerene, human exposure, nanomaterials, toxicologic assessment, histopathology, nanoparticle toxicity, human health risk