Date of Award
Spring 2026
Document Type
Open Access Dissertation
Department
Chemical Engineering
First Advisor
Zhenmeng Peng
Abstract
The increasing demand for energy and materials, coupled with the depletion of fossil resources and accumulation of persistent polymeric wastes, necessitates the development of sustainable and energy-efficient conversion technologies. This dissertation explores nonthermal plasma (NTP)-enabled reaction engineering as a versatile platform for the rapid, ambient, and catalyst-free or catalyst-assisted upcycling of biomass and synthetic polymers into value-added fuels and chemicals.
Dielectric barrier discharge (DBD) NTP reactors were developed and systematically optimized to overcome the kinetic and thermodynamic limitations of conventional thermochemical processes. For lignocellulosic biomass, ambient hydrogen and carbon dioxide plasmas enabled fast hydrogenolysis of lignin and depolymerization of lignin, cellulose, and real woody biomasses, producing aromatic monomers, bio-oils, and light hydrocarbons without high temperatures, pressures, or solvents. Reactor scale-up and the use of CO2 as a low-cost plasma medium significantly enhanced throughput and energy efficiency, achieving record output-to-input energy ratios while simultaneously enabling CO2 utilization.
For synthetic polymers, including high-density polyethylene (HDPE) and polyethylene glycol (PEG), NTP-assisted hydrogenolysis and hydrolysis achieved complete conversion within minutes under ambient conditions. Through integrated reactor and reaction engineering, noncatalytic HDPE hydrogenolysis reached unprecedented energy efficiency, demonstrating the feasibility of electricity-driven, catalyst-free plastic upcycling. The coupling of NTP with acidic zeolites further enabled ultrafast, selective hydrocracking of HDPE into light hydrocarbons, revealing synergistic radical-carbocation mechanisms. PEG decomposition under water-vapor plasma provided mechanistic insights into plasma-driven bond cleavage and liquid-to-gas secondary reactions, supported by density functional theory calculations.
Overall, this work establishes NTP as a scalable, energy-efficient, and flexible platform for the sustainable conversion of renewable biomass, plastic waste, and CO2 under mild conditions. The insights gained into plasma-material interactions, reaction pathways, and reactor design provide a foundation for advancing plasma-enabled technologies toward practical circular carbon and materials economies.
Rights
© 2026, Parsa Pishva
Recommended Citation
Pishva, P.(2026). Nonthermal Plasma-Assisted Conversion of Biomass and Plastics Into Value-Added Chemicals. (Doctoral dissertation). Retrieved from https://scholarcommons.sc.edu/etd/8905