Volume reduction of high impact polystyrene and polyethylene terephthalate plastic resins and wastes through microwave pyrolysis

Date of Publication

2008

Document Type

Bachelor's Thesis

Degree Name

Bachelor of Science in Chemical Engineering

College

Gokongwei College of Engineering

Department/Unit

Chemical Engineering

Thesis Adviser

Susan Abogado Roces

Defense Panel Chair

Florinda Tiangco Bacani

Defense Panel Member

Dennis Ng Yu
Kathleen Bernardo Aviso

Abstract/Summary

Plastics manufactured to meet specific functional needs have not only brought ease and convenience but also environmental problems. With the advent of Clean Air Act of 1999 and the Ecological Solid Waste Management Act of 2000, since incinerations have been banned, different industries have been disposing their wastes, including plastics, in landfill sites. However, landfill process has not been successful in solving the environmental problems.

Microwave pyrolysis is a non-burn technology that has been gaining acceptance along with other advanced waste treatment technologies. It involves the chemical decomposition of wastes by heating in the absence of oxygen and can achieve rapid heating at high temperatures.

Taking these into consideration, this research focused on the microwave pyrolysis of high impact polystyrene (HIPS) and polyethylene terephthalate (PET) resins and plastic wastes.

PET samples were pyrolyzed at 500°C at nitrogen atmosphere. Residence times were varied among 5, 10 and 15 minutes. Similarly, plastic to charcoal weight ratios of 0.5/1, 1/1, 1.5/1, 1/0.5 and 1/1.5 were considered in the experiments. Particle sizes were also varied between 2 mm (Mesh 9) and 5 mm (Mesh4). For PET resins, Mesh 9 particles produced better results. The plastic to charcoal weight ratio of 1:1.5 produced the greatest decomposition of 41.55% at 15 minutes. The greatest amount of oil was 5.42% and was obtained at 0.5:1 plastic to charcoal weight ratio at 15 minutes. For PET wastes, 2mm particles similarly produced better results. The plastic to charcoal weight ratio of 0.5:1 produced the greatest decomposition of 37.78% at 15 minutes. In the same way, the greatest amount of oil was 5.18% and was obtained at 0.5:1 plastic to charcoal weight ratio at 15 minutes.

HIPS samples, on the other hand, were pyrolyzed at 700°C at nitrogen atmosphere. Residence times were also varied among 5, 10 and 15 minutes. Similarly, plastic to charcoal weight ratios of 0.5/1, 1/1, 1.5/1, 1/0.5 and 1/1.5 were considered in the experiments as well. Particle sizes were also varied between 2 mm (Mesh 9) and 5 mm (Mesh 4). For HIPS resins, 2 mm particles produced better results. The plastic to charcoal weight ratio of 0.5:1 and 1:1.5 both produced the greatest decomposition of 67.36% at 15 minutes. Similarly, the greatest amount of oil was 9.41% and was obtained at 1:1.5 plastic to charcoal weight ratio at 15 minutes. For HIPS wastes, 2 mm particles similarly produced better results. The plastic to charcoal weight ratio of 0.5:1 produced the greatest decomposition of 56.29% at 15 minutes. Likewise, the greatest amount of oil was 11.32% and was obtained at 0.5:1 plastic to charcoal weight ratio at 15 minutes.

The results implied that the percentage of decomposition and oil increased along with increasing residence time and with decreasing particle size. Similarly, more plastic particles were pyrolyzed with increasing amount of microwave absorber. On the other hand, the oil composition was generally not affected by particle size nor by the plastic to charcoal weight ratio.

Abstract Format

html

Language

English

Format

Print

Accession Number

TU15675

Shelf Location

Archives, The Learning Commons, 12F, Henry Sy Sr. Hall

Physical Description

211 leaves : illustrations ; 28 cm.

Keywords

Polystyrene; Polyethylene; Plastics--Environmental aspects; Plastics--Recycling

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