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Dissertation
Depolymerization of the waste polymers in municipal solid waste streams using induction-coupled plasma technology
Doctor of Philosophy (Ph.D.), Drexel University
Jun 2000
DOI:
https://doi.org/10.17918/00000828
Abstract
A significant, valuable percentage of today's municipal solid waste stream consists of polymeric materials, for which almost no economic recycling technology currently exists. This polymeric waste is incinerated, landfilled or recycled via downgraded usage. Thermal plasma treatment is a potentially viable means of recycling these materials by converting them back into monomers or into other useful compounds. The technical, laboratory scale, feasibility of using an induction-coupled RF plasma [ICP] heated reactor for this purpose has been demonstrated in the present study. Polyethylene [PE], polypropylene [PP] and polyethylene terephthalate [PET], the model polymers chosen for the study, were injected axially through the center of an ICP torch. 68% of PE, 78% of PP and 75% of PET were converted into gaseous products. Ethylene and propylene were the primary gaseous products of decomposition of the former two polymers and acetylene was the primary product of the depolymerization of PET. The amount of propylene obtained in PE depolymerization was significantly higher than anticipated and was believed to be due to [beta]-scission reactions occurring at the high plasma temperatures. Statistical design of experiments was used to determine the influence of individual variables. Analysis of results showed that plasma plate power, central gas flow rate, probe gas flow rate, powder feed rate and the interaction between the quench gas flow rate and power input were the key process parameters affecting the yield of monomer in the product gas stream. Depolymerization of a PE + PP mixture yielded concentrations of propylene and ethylene close to those predicted from weighting the concentrations of products from the individual polymers. 75.5 wt.% of the mixture was converted into monomers. TEM analysis of the carbon residues collected from different locations of the reactor indicated the formation of some novel carbon structures, including carbon nanotubes. The presence of these novel forms of carbon could potentially lead to several high valued applications of this process such as production of high surface area catalysts, hydrogen storage materials, and materials for electronic applications such as super capacitors, flat panel displays etc.
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Details
- Title
- Depolymerization of the waste polymers in municipal solid waste streams using induction-coupled plasma technology
- Creators
- Ravikishan Reddy Guddeti
- Contributors
- Elihu D. Grossmann (Advisor)Richard Knight (Advisor)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- xvi, 161 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- Chemical (and Biological) Engineering [Historical]; College of Engineering (1970-2026); Drexel University
- Other Identifier
- 991014970310604721