Production and characterisation of pyrolysis oil from discarded medical plastic (syringe) waste with common rail direct injection engine assessment

Abstract

This study explores the potential of converting syringe plastic waste into an alternative fuel through pyrolysis. Since sy-ringes are primarily made of polypropylene, they were thermally decomposed in a batch reactor, producing a maximum pyrolysis oil yield of 76% at 400–500°C. The produced syringe plastic oil (SPO) was characterised for key fuel properties and blended with diesel at 20%, 30%, and 40% proportions. The performance of the engine and the emission characteristics of these blends were tested experimentally on a common rail direct injection diesel engine. Of the fuels tested, the D80SPO20 mixture proved to be as efficient as diesel with the brake thermal efficiency of 26.9% and brake specific fuel consumption of 0.27 kg/kWh at full load. This mixture was also found to result in a significant reduction in carbon mon-oxide, hydrocarbons and smoke emission with a slight increment in NOx relative to diesel. On the whole, the findings show that low-percentage SPO30, especially D80SPO20, provide a favourable combination between engine efficiency and emis-sion reduction, proving the potential of the syringe plastic pyrolysis oil as a sustainable alternative of diesel fuel in part.