04/22/2022
By Sokny Long

The Francis College of Engineering, Department of Plastics Engineering, invites you to attend a Doctoral Dissertation Proposal defense by Taofeng Lu on “Chemical Recycling of Mixed Plastic Waste Using Safer Solvents and Supercritical Water.”

Ph.D. Candidate: Taofeng Lu
Defense Date: Friday, May 6, 2022
Time: 1 to 3 p.m. EST
Location: Southwick 240

Committee Chair (Advisor): Wan-Ting (Grace) Chen, Assistant Professor, Plastics Engineering, University of Massachusetts Lowell

Committee Members:

  • Margaret Sobkowicz Kline, Associate Professor, Plastics Engineering, University of Massachusetts Lowell
  • Hsi-Wu Wong, Associate Professor, Chemical Engineering, University of Massachusetts Lowell
  • Fanglin Che, Assistant Professor, Chemical Engineering, University of Massachusetts Lowell

Brief Abstract:
Plastics are widely used because they are robust and cost-effective materials. However, improper disposal of plastics has become a serious environmental issue. Particularly, recovering plastic waste from the ocean is challenging and expensive. Conventional plastic recycling methods such as mechanical recycling cannot handle mixed plastics and usually lead to down-cycling, mainly due to the inferior properties of recycled products. To address this problem, solvent recovery processes and hydrothermal processes (HTP) with supercritical water were used in this study to convert the plastic waste into useful products. Density separation coupled with dissolution and precipitation successfully recovered Acrylonitrile butadiene styrene (ABS) from a stream of toy waste. Material properties of recovered ABS were characterized and compared to feedstock ABS. In HTP, reaction temperatures and reaction times were first studied through HTP of polyethylene-based ocean-bound plastic waste. The polymer degradation mechanism was explored by characterizing the gas, oil, and solid products. Then, HTP was used to convert polyolefin mixture containing both polyethylene and polypropylene. Preliminary data shows that including other types of polyolefins with PE appears to reduce the reaction severity of producing value-added chemical products from PE via HTP. Finally, this PhD dissertation will also explore the effect of contaminants on HTP of polyolefins. Contaminants including non-polyolefin polymer (e.g., polyterephthalate, PET, and polystyrene, PS), organic plastic additives (e.g., plasticizers that are commonly used in polyolefin bottles, paper), and inorganic plastic additives (e.g., calcium carbonate and aluminum foil) will be used. Results from this study would contribute to developing an efficient, robust and cost-effective chemical recycling method for challenging heterogeneous plastic waste.

All interested students and faculty members are invited to attend the proposal defense.