Nien-Hwa Linda Wang
Maxine Spencer Nichols Professor, Davidson School of Chemical Engineering, Purdue University
“Converting Polyolefin (Plastic) Waste into Fuels”
The rapid growth of plastic waste over the past 60 years, coupled with low collection (14%) and recycling rates (<9%), has resulted in rapid accumulation of plastic waste in landfills and the oceans. If the current trend continues, the planet will have 30 billion tons of plastic waste and more plastic waste than fish in the oceans by 2050. Plastic waste degrades slowly, releasing toxic chemicals into the environment and threatening ecosystems and food/water supplies. Remediation costs of the pollution are unaffordable, estimated to be many times of the global GDP. Existing methods for reducing waste accumulation have been limited. Incineration is hampered by generation of greenhouse gases and toxic gases, low energy recovery, and little profits. Mechanical recycling remains limited to a few types of sorted plastics. Pyrolysis can convert mixed plastic waste into crude oil, but fluctuations in crude oil prices make its profits unpredictable. The Purdue team is investigating two methods for converting plastic waste into valuable products: (1) Selective Sequential Extraction and Adsorption (SSEA) for converting plastic waste into pristine polymers and (2) hydrothermal processing (HTP) with sub- or super-critical water for converting plastic waste into fuels and other feedstock chemicals. The new methods potentially are more energy efficient and produce less greenhouse gases than incineration and mechanical recycling. They may also help transform the current linear path (from crude oil, to plastics, to landfills) to a more economical and sustainable circular path, while reducing waste accumulation and risks to the environment.
Linda Wang is the Maxine Spencer Nichols Professor of Chemical Engineering at Purdue University. Her research interests are in chemical and biochemical separations. She is internationally known for her research contributions in multi-component chromatography and simulated moving beds. The chromatography simulation and design tools developed in her group have been used for designing processes for nuclear waste treatment and for removing radioactive contaminants in sear water at Fukushima, Japan. Her group also helped design the separation and purification system for producing a medical isotope from non-weapon grade uranium. She received the Gold Award from Purdue Foundry for her work on the recovery of rare earth elements from coal ash and other complex mixtures. She was inducted into the Purdue Research foundation’s Innovators Hall of Fame in 2018.