1. RESULTS and DISCUSSION
The Effects of weathering on the release of TiO2 nanoparticles in paint dust
Adam Nored1 and Ilias G. Kavouras2, Ph.D.
1 Interdisciplinary Engineering Program, College of Engineering, University of Alabama at Birmingham, Birmingham, AL
2 Department of Environmental, Occupational and Geospatial Health, City University of New York, New York, NY
INTRODUCTION
Engineered nanoparticles(ENPs) have been the source for many major improvements in construction materials quality and capability. In the field of paint, these ENPs have been used to make the paint more resilient, and have the capabilities to antimicrobial, self-cleaning, and water repellence.
Many of the nanomaterials used have been shown to have adverse health reactions in their pristine forms.
ENPs may be released due exposure to the elements. We want to see if that is possible.
OBJECTIVE and AIMS
Main objective: Whether nanomaterials in paints may be released due to weathering effects
Aim #1: Determine the size distribution of nano-enabled paint sanding dust throughout a year long weathering test.
Aim #2: Determine if there are changes to the paint makeup over time do to weatherization.
RESULTS and DISCUSSION
METHODS
CONCLUSIONS
The abrasion particle concentration stays relatively high at the beginning of the sanding process until the last few months of the study.
While the sanding time needed varied greatly from sample to sample, there is a noticeable drop-off in the time used to reduce the particle concentration, with the last few samples needing less than half the time to drop to a concentration of less than 20,000 particles/cm3
The first several months of the study, the number concentration is very stable The maximum particle concentration of the samples lowers significantly towards the end of the study. In the 9th month of the study the maximum particle concentration is 146,632 particles/cm3. In the 10th month the maximum concentration is 112,000 particles/cm3 and it drops to 63,000 particles/cm3 in the last month of the study.
Particle concentration due to abrasion is markedly less than at the beginning of the study
There is proof that the nanoparticle infused paint does physically change over the course of a year exposure to natural outdoor conditions.
The nanoparticles are escaping the paint media over time
More work needs to be done to chemically characterize the free ENPs due to weatherization effects
SEM images of nano-infused paint dust The bright specks are the metal oxides in the paint used. EDXS from the SEM verified the composition of the particles
SEM samples show less bright spots, and it is harder to find TiO2 using EDXS in the weatherization samples the longer the study goes on.
Painted wood panels were set up and exposed to natural weathering conditions. A panel was removed every month and abraded to determine particle size and use the paint dust for other testing
The equipment used for size distribution and particle counting includes a MSP model 1000XP Wide range Particle Spectrometer (WPS), a TSI AeroTrak 8220 handheld optical particle counter, and a TSI Condensation Particle Counter 3007 (CPC).
The filter pumps were set to 5 liters per minute. While the entire chamber had continuous airflow and was contained inside a safety cabinet.
Figure 1. Experimental setup
Attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) is used to determine the ability of light to pass through a sample’s surface to a depth of just micrometers
Image A shows that over the first several months, there was a slow change in the transmissivity of the samples over time.
Image B, which is the spectra for the last three months of the study, show a marked increase in the rate of change in the transmissivity.
Towards the end of a one year weatherization study the nanoparticle infused paint is quickly losing its ability to prevent light A B