Characterisation of Pyrolysis Oil Produced from Seaweed and Plastic Wastes for Engine Applications

This research evaluates the potential of pyrolysis oils derived from plastic wastes and seaweed (specifically waste high-density polythene, HDPE) for engine applications. Utilizing a thermal pyrolysis process within a batch reactor, seaweed and HDPE were converted into oil, following preliminary thermogravimetric and CHNS assessments. Experimental conditions varied with temperatures between 400°C to 550°C, maintaining a 60-minutes residence time and a 2-mm feedstock particle size. Results indicated optimal oil yields at 475°C for seaweed (42.93%) and 525°C for HDPE (61.29%). Analytical techniques, including Fourier transform infrared spectroscopy (FTIR), revealed that while seaweed oils were rich in oxygenated compounds, aromatic, phenolic, HDPE oils predominantly contained aromatics and hydrocarbons. Given the higher viscosity (12.01 Cst), density 1.19 (g/cc), and reduced calorific value 29.11(MJ/kg) of seaweed-derived oils compared to HDPE oils (1.63 Cst, 0.78 (g/cc) and 42.89 (MJ/kg respectively) respectively the former might necessitate further refinement for engine compatibility. Conversely, HDPE-derived oil, aligning well with many engine fuel parameters, requires real-world engine testing to validate its potential.