Production and Physicochemical Characterization of Polyethylene Pyrolysis Oil from Sachet Water LDPE Waste

Abstract

This study investigated the production and characterisation of polyethylene pyrolysis oil obtained from waste low-density polyethylene materials, specifically sachet-water packaging bags. The polyethylene waste was collected, sorted, washed, rinsed, and dried. A 15 kg portion of PE was subjected to thermal pyrolysis at 400 °C for 3 hours in the absence of oxygen and was then distilled for a further 3 hours in a batch reactor. The condensed liquid product comprised 3.0 kg of polyethylene pyrolysis oil and was evaluated for selected physicochemical and instrumental properties. The residue obtained was 9.5 kg. The measured physicochemical properties included viscosity, density, refractive index, turbidity, pH, adhesion, drying time, and water solubility. The oil had a viscosity of 17.7 mPa·s, a density of 0.99 g/mL, a refractive index of 1.400, a turbidity of 50 NTU, and a pH of 6.7, and it was insoluble in water. Fourier-transform infrared spectroscopy indicated the presence of hydrocarbon-related and oxygen-containing functional groups in the pyrolysis oil. X-ray diffraction analysis suggested low crystallinity and predominantly amorphous characteristics. Scanning electron microscopy showed a relatively smooth and homogeneous surface in the prepared sample, while thermogravimetric and differential thermal analyses indicated thermal degradation behaviour, with mass-loss events observed during heating. The findings show that waste polyethylene can be converted into a liquid pyrolysis product with measurable physicochemical and structural characteristics. Further studies are required to determine its detailed chemical composition, safety, distillation behaviour, and suitability for specific industrial applications.