Abstract
This dissertation presents three projects aimed at advanced material recovery and valorization of Municipal Solid Waste (MSW). MSW is a heterogeneous material with varied chemical, physical, and biological properties. The U.S. generates 286 million tons of waste annually Creating environmental issues giving low recycling rate, particularly for plastic waste. Industries such as building and construction, automotive, electronics, and energy-related products drive the demand for plastic. A proper assessment and characterization of MSW is therefore essential to identify the composition to design an effective valorization pathway. MSW is inherently heterogeneous, containing 50-60% biogenic materials alongside various plastics, primarily single-use polymers. This composition presents unique opportunities for material recovery through both mechanical, chemical processing and thermochemical conversion. This research examines MSW samples from material recovery facilities in Utah and Michigan, employing analytical, chemical, and physical methods to unlock their valorization potential across three interconnected studies. The dried MSW was ground to a fluff and characterized by energy dispersive X-ray (EDS), thermogravimetric analysis (TGA), and Fourier transform infrared Spectroscopy (FTIR), X-ray diffraction (XRD), GC-MS, and calorific measurement. These analyses revealed the complex composition of MSW, providing baseline data for further recovery pathways. The characterized fluff was mechanically processed through compression and extrusion into composites with enhanced thermal and physical properties. Building on this data, selective extraction was performed to recover high-yielding near-virgin polyethylene and polystyrene plastics and high calorific biogenic MSW using xylenes and toluene as solvents, achieving 32% and 26% yield for xylene and toluene, respectively. The recovered plastics were analyzed in terms of melt, thermal degradation, and rheological properties, and compared to virgin plastics. The plastics had properties comparable to virgin plastics in terms of their thermal, rheological, thermogravimetric, and mechanical strength. The biogenic MSW remaining after the polymer extraction was pyrolyzed under nitrogen flow at 500 °C to understand the effect of varying conditions on the bioproducts produced. GC-MS and electrospray ionization mass spectrometry (ESI-MS) analyses revealed that the bio-oil contained abundant oxygenated, aromatics, and alkanes derived from cellulosic and lignocellulosic decomposition, along with contributions from residual plastic degradation. The biochar product was compounded with polymer matrices using twin-screw extrusion to fabricate composite materials. The composite was analyzed in terms of its mechanical and thermal properties ( TGA, DSC, rheology), water absorption capacity, and density.