A research team has studied the use of fatty acids in groundwater decontamination, non-profit institute the AIP (American Institute of Physics) reported.
Although compounds derived from ammonia – called amines – are used in industrial processes like carbon capture and desalination, these compounds often ended up as groundwater pollutants and could affect nearby ecology and plant growth, the 6 March report said.
By combining experiments and simulations, the research team found that fatty acids could help separate and trap pollutants from the water, while finding short chain fatty acids could also make specific pollutants more soluble.
In their tests on the toxic amine pyridine, the group found that fatty acids compete with the pollutant for hydrogen bond interactions with the water.
“Hydrogen bonds are weak attractions that help water molecules ‘stick’ to each other and also let water interact with many dissolved chemicals,” study author Erica Pensini was quoted as saying.
“In our mixtures, pyridine and fatty acids both try to interact with water this way, but fatty acids also have an oily tail that water does not like.”
The length of this tail affects an acid’s interaction with pyridine. While short tails prevent pyridine from gathering into large clusters, long tails disrupt how it mixes with the water, potentially forming a thin film at the water’s surface that can trap the pyridine.
The group was surprised by how much this small parameter affected the effectiveness of groundwater pollutants. By tuning these molecular interactions, they were able to address one of the key challenges in groundwater treatment, the dissolved phase of the pollutants.
“Just changing the fatty acid tail length moved the system away from ‘everything stays mixed’ to ‘pyridine separates into droplets,’ and then further to a self-assembled surface film that can physically trap those droplets – essentially turning a basic interfacial phase transition into a practical, low-energy separation mechanism,” Pensini explained.
The researchers were exploring additional factors that could affect groundwater decontamination, including the salinity of the water and interactions between multiple contaminants, the report said.
AIP is involved in research and analysis to advance change in the physical sciences.
