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Haoran Wei
February 6, 2020

Focus on new faculty: Wei illuminates water contaminants

Written By: Alex Holloway

Haoran Wei has spent his academic career illuminating contaminants in water.

Through using light to identify chemicals in water, Wei has worked to develop technologies that can help remove potentially harmful chemicals like pharmaceuticals or herbicides.

“All of my research has been about manipulating light to achieve these purposes,” Wei says.

Now he’s bringing that expertise to UW-Madison as an assistant professor of civil and environmental engineering. Wei joined the College of Engineering in January 2020. His research falls under the civil and environmental engineering department’s environmental chemistry and technology focus area. Wei earned his bachelor’s degree from Shandong University in China in 2010, then attended Tsinghua University to earn his master’s degree. As a graduate student, he studied materials like activated carbon and carbon nanotubes to make absorbents for removing pharmaceuticals from water.

“Conventional water treatment plants can’t remove such chemicals efficiently,” he says.

Before finishing at Tsinghua University, Wei began looking for opportunities in the United States, where he says research on cleaning water is more advanced. He attended Virginia Tech as a doctoral student and earned his PhD in February 2018.

For his PhD research, Wei used Raman scattering, which measures frequency shifts when light photons encounter vibrational bonds in molecules. Researchers can identify molecules by measuring the amount of energy gained or lost in the interaction between photons and target molecules. In particular, Wei used surface-enhanced Raman spectroscopy—a method that employs Raman scattering—to look for chemicals like atrazine, carbamazepine, and other aromatic amines. The method he developed is so sensitive it can pick up traces of the chemicals well below allowable safe limits set by the Environmental Protection Agency.

“Raman scattering is like the fingerprint of a chemical,” Wei says. “I developed a method using it that can detect these compounds, within a matter of several seconds, down to a concentration as low as a nanomolar per liter.”

Wei has also developed new water treatment technology that employs sunlight-harvesting nanoparticles. The light, once absorbed, is converted into heat, which creates highly energetic electrons that aid in breaking down chemicals to clean water. He says the method could have broad applications for removing water contaminants.

“You’re not only limited to removing pharmaceuticals and herbicides,” he says.

While at UW-Madison, Wei plans to continue research on emerging contaminant detection and removal. Per- and polyfluoroalkyl substances (PFAS), which are known as “forever chemicals” due to their longevity upon entering water sources, are, Wei says, a “really big deal.” He wants to develop new ways to identify and track them in water.

PFAS chemicals, according to the Centers for Disease Control Agency for Toxic Substances, may interfere with the human body’s natural hormones, increase cholesterol, adversely affect the immune system and increase the risk of some cancers. PFAS are in the blood of 99 percent of Americans and have been found in water in cities across the United States, including Madison and other municipalities across Wisconsin.

Beyond his contaminant research, Wei also hopes to develop systems to help clean water in areas without power.

“I want to help design a reactor that can be used to provide drinking water to off-grid areas,” he says. “For example, in regions where there’s no electricity, I can use sunlight to provide drinking water.”

Much as the advances in water research drew Wei to the United States, he says UW-Madison’s collaborative spirit and long history of excellence in the field drew him to the university.

“People here really care about the water,” Wei says. “There is a big focus on PFAS and there are some other contaminants like microplastics and herbicides that I want to continue to work on. I think this is the best place to do it.”