Identification and Characterisation of Major Hydrocarbons in Thermally Degraded Low Density Polyethylene Films

Abstract

The vast application of Low Density Polyethylene (LDPE) in packaging, greenhouses, homes etc has led to its huge accumulation as a municipal solid waste with monumental health, economic and environmental consequences. Since these are non-biodegradable and their photodegradation occurs only over a very long period, their economic conversion to energy products through pyrolysis is the thrust of this study. LDPE sample collected from the University of Ilorin Community was thermally degraded in a pyrolyser at temperatures ranging from 203 – 400 ^oC. The products of pyrolysis were in three (3) states of matter and both the liquid and solid products were analysed using FTIR to determine the functional groups and GC- MS for the hydrocarbons present in the products. For the GC-MS analysis, the peaks that had 90% above quality when compared with the compounds in the installed NIST11 library were reported. There were alkanes, alkenes, halogenated alkanes, and very few aromatics in the liquid product and, the hydrocarbons were observed to range between C₁₀ - C₂₇. The FTIR and GC-MS results show the potential of the oil obtained as renewable source of energy while that for residue shows its inherent energy content. The liquid product was refluxed over molecular sieve catalyst (US 2882244A) and the calorific value was found to increase from 13,974 kJ/kg to 15,815.52 kJ/kg and this is found to be comparable to the range for lignite and dry wood. 

Key words: environmental pollution, solid wastes, LDPE, pyrolysis, hydrocarbons, Calorific value.