Perfluorooctanic acid or PFOA is a man-made chemical byproduct of the production of Teflon, and does not break down in the environment, leaving water sources contaminated. The health effects this has on humans is largely unknown, but it has been found to be present in low levels in the bloodstream of most people and can cause adverse health effects such as cancer, development and reproductive detriments, and liver damage, according to the CDC. The current method of removal for PFAs utilizing activated carbon is energy-intensive and costly, and still has potential to leak PFAs into water sources when the carbon is disposed of. To remove PFOAs from water, a novel method of liquid-liquid extraction using a polydimethylsiloxane (PDMS) membrane was studied. This process, known as perstraction, was tested measuring the absorptive properties of different metallic oxide and nanoparticulates as well as various organic solvents. While the perstraction test device is still being manufactured, experimentation has found that metal oxides, specifically copper(II) oxide and zinc oxide, improve the absorption qualities of PDMS membranes in PFOA solution. Diffusivity of butanol, hexanol, and octanol through various membranes have all been studied to determine the best potential organic phase. Since methods commonly used to detect PFAs/PFOA concentration directly are expensive and time consuming, PFOA concentration has been indirectly measured by a conductivity meter, although UV-Vis spectroscopy also shows promising correlation within a wavelength of 205-210nm for PFOA detection. Further testing, including the use of a scanning electron microscope (SEM) and ion chromatography, are being explored as viable means of assessing efficacy of perstraction as a method of removal of PFAs. The final device will hold a membrane which separates two chambers, allowing the organic solvent to pass through the membrane which will absorb the PFOAs as it passes through, leaving the water free of PFOA and safe for the environment.
Authors: Ryan Armstrong, Sean Chen, Megan Flood, Chris Marcelino
Faculty Advisor: Catherine Almquist, Chemical Paper and Biomedical Engineering
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