AUSTIN – Researchers at the University of Texas’ Department of Petroleum and Geosystems Engineering say they have developed a method to separate oil from water with magnetic nanoparticles.

The current method of separating oil from water is called gravitational separation, but a study published earlier this year in the Journal of Nanoparticle Research states researchers used the nanoparticles with surface coatings for water treatment to quickly and efficiently remove the oil droplets from water. A nanoparticle is considered to be of great scientific importance due to its size (1-100 nm), and are viewed as a bridge between atomic/molecular structures and larger bulk materials.

The current method can separate around 95 percent of the oil from produced water, leaving small oil droplets that are hard to extract. The last five percent “makes water treatment and disposal more challenging and environmentally risky,” UT PGE said.

“This new technique is really aimed at removing that little bit of oil in that water that needs to be removed before you can consider it treated,” said Saebom Ko, a research associate in the Department of Petroleum and Geosystems Engineering and lead author on the study. “The advantage of employing magnetic nanoparticles is that the small oil droplets that attach to the nanoparticles are much more quickly separated from water than traditional physical separation processes because magnetic force can be orders of magnitude larger than gravitation.”

UT PGE said, “Ko worked with a team including petroleum and geosystems engineering associate professor Hugh Daigle, biomedical engineering professor Thomas Milner and researcher Chun Huh to design surface coatings for magnetic nanoparticles that could be used for the removal of oil.”

The team used high gradient magnetic separation for the process, one that UT PGE says has been used previously in mining to remove metals and in the food industry to remove toxic particles. The nanoparticle surface coating was charged in a way so that it would “latch on” to the negatively charged oil droplets through electrostatic attractive force and draw it out of the water.

“It’s a simple idea,” Daigle said. “We are leveraging the magnetic properties of these nanoparticles to get them to stick to the oil droplets and essentially magnetize the oil droplets so they can be pulled out with a magnet.”

UT PGE added the researchers envision designing a method for the nanoparticles to clean up oil spills in the ocean, and are exploring how it can be used to remove lead and other contaminants from drinking water.