In the more than 100 years since researchers developed synthetic plastic, it has become the world’s most common engineered material—used in nearly everything humans produce, from automobiles and food packaging to medical implants and electronics.
While the technology used to produce plastics has advanced rapidly, the opposite is true for methods to recycle them: Of the 400 million tons of plastic produced each year, 9% or less is recycled. Currently, there are no industrial-scale technologies that truly recover and reuse the polymers that make up plastics.
But recycling researchers are trying to catch up. One promising innovation is solvent-based or dissolution recycling, in which plastic polymers are chemically dissolved and separated, ready to be reborn as new plastic products. University of Wisconsin-Madison chemical engineers are on the leading edge of this technology and are eager for industry to adopt dissolution recycling at the commercial scale.
In a paper published in July, 2025, in the journal Nature: Chemical Engineering, they assess the current challenges and future of solvent-based recycling projects around the world—including their own method, solvent-targeted recovery and precipitation, or STRAP.
UW-Madison PhD student and co-author Charles Granger says one major goal of this paper is to show the research community and industry just how far this type of recycling has advanced. “Dissolution recycling is a viable technology worth adopting,” he says. “Even at this early stage, it promises both significant environmental benefits over virgin plastic production and strong economic potential. We’re hoping to encourage broader participation in advancing dissolution recycling by highlighting the current state of this technology.”
Most plastics recycling today is mechanical. That means the plastic is ground and reprocessed into a new material. But this type of recycling has limitations; because the grinding process destroys the long polymer chains that make up plastic, it can only “downcycle” the plastic into lower quality products that can’t be recycled at all. The process is also limited to a small, specific set of single layer plastics. Mechanical recycling doesn’t work to recycle items such as plastic films, multilayer plastics and other complex materials that make up a large percentage of plastic waste. And mechanical recycling does not remove color or other inorganics that are added to the plastics.
Solvent-based recycling methods, however, can overcome many of these issues. Solvent processing “deep cleans” plastics, removing additives like colors and other chemicals. It can also separate out different types of plastic, allowing recyclers to process mixed plastic materials like electronic waste, unsorted bales of plastic, and multilayer food packaging. Most importantly, solvent processing leaves the plastic’s long polymer chains intact, creating a final product that is “near virgin” and doesn’t have to be downcycled; a recycled water bottle can be recycled into a new water bottle using the recovered resins.
UW-Madison’s involvement in solvent-based recycling began in 2019, when Jesse Banick, then a chemical engineering senior, approached George Huber, a professor of chemical and biological engineering, with an intriguing independent study proposal. He had just finished a co-op at Neenah, Wisconsin-based Amcor, a company specializing in multilayer plastic packaging where he currently works. Banick wanted to investigate whether some of the solvent-based techniques Huber used to produce fuels and chemicals from biomass (like wood and agriculture waste) could be used to recover the resins from multilayer plastics.
Huber was intrigued, and his students developed proof-of-concept experiments in which they used a series of solvents to dissolve and recover various plastics from a multilayer plastic film. The concept showed promise. For Huber, it was a chance to take all he had learned about solvents and apply that expertise to a critical societal need.
Over the next six years, the team grew to include colleagues Styliana Avraamidou, Victor Zavala Tejeda and Reid Van Lehn along with a generation of UW-Madison chemical engineering graduate students who have developed and refined the patented STRAP process. Collaborators at other universities also joined in as part of the Department of Energy-sponsored Center on the Chemical Upcycling of Waste Plastics led by Huber.
According to the Nature: Chemical Engineering paper, STRAP and similar technologies face two major bottlenecks: removing contaminants and scaling up the process. “We need to think about complexity. There are various types of contaminants that can be present in plastics,” says Van Lehn, who uses computational techniques to identify the right chemical solvents to use in each step of the STRAP process. “We are figuring out ways to remove small-molecule colorants, as well as materials like titanium dioxide and other sources of color. A lot of our fundamentals right now are focused on the lab scale and how we remove these contaminants from complex waste sources.”
At the same time, the group is also working on ways to take STRAP to the industrial scale. Currently, the team is close to launching a pilot-scale plant at Michigan Technological University capable of recycling 55 pounds of plastic per hour. “We started with very small, simple reactors in the laboratory,” says Huber. “Now we’ve gone to more complex reactors in the lab; hopefully our pilot-scale system will be operational in early 2026. We are now working to find industrial partners who are interested in sustainability and plastic recycling.”
STRAP is just one solvent-based recycling technology nearing commercial viability. CreaSolv, developed by the Fraunhofer Institute for Process Engineering and Packaging; UpSolv, a company in Montreal; U.S.-based Purecycle; and APK Newcycling based in Germany all use solvent-based techniques to recycle various types of plastics. And all are working to overcome similar bottlenecks.
The UW-Madison team, however, doesn’t see the other efforts as competitors; in fact, Van Lehn says he hopes colleagues worldwide can help each other move forward as a field. “There’s so much plastic waste material out there and everyone is tuned to processing a particular feedstock,” he says. “We estimate that in North America, Europe and Japan, solvent-based recycling could be close to a $25 billion per year business. It’s hard to imagine one company capturing that whole market. There’s enough plastic for everyone.”
Other UW-Madison authors include Zhuo Xu, Kevin Sanchez-Rivera, Charles Granger, Panzheng Zhou, Aurora del Carmen Munguia-Lopez, Ugochukwu M. Ikegwu, Styliana Avraamidou, and Victor M. Zavala. Other authors include Ezra Bar-Ziv of Michigan Technological University and Steven De Meester of Ghent University in Belgium.
The authors acknowledge support from the US Department of Energy, Office of Energy Efficiency and Renewable Energy, Bioenergy Technologies Office under Award Number DEEE009285.
Top image caption: PhD student Charles Granger and Kevin L. Sánchez-Rivera (PhDChemE ’24) are part of generation of CBE graduate students who have worked to develop the STRAP recycling process. Photo: Joel Hallberg