Discernment of synergism in co-pyrolysis of HDPE and PP waste plastics for production of pyro-oil: Mechanistic investigation with economic analysis and health risk assessment

Abstract

Plastic waste is a major environmental challenge globally as it can hazard the soil, groundwater, marine, and land creatures. It also emits several toxic gases in open environment when heated up. The ceaseless demands for plastic materials due to wide applications generated a high volume of plastic waste which can impact sustainability development. The present study reports synergism in co-pyrolysis of mixed waste plastic for production of value-added products with economic analysis and health risk assessment. The characterization results of mass spectroscopy and NMR revealed that the product contains different types of hydrocarbons such as paraffins, aromatic, cyclic olefins, and lower hydrocarbons. The physicochemical characterization of pyro-oil showed similar fuel properties to that of commercial diesel (CD). Blending of pyro-oil obtained from HDPE:PP (20:80) improved the fuel quality that results in high brake thermal efficiency (BTE) and reduced brake-specific fuel consumption (BSFC). At the maximum load condition, ∼19.17% and 29.43% enhancement in BTE were observed with 10% and 20% PO blending, respectively. Also, ∼23.4% of fuel consumption was reduced when 20% PO blend was used with CD. The results showed that the maximum CO emission of 30.93% could be reduced by blending 10% PO. The engine performance and combustion characteristics revealed that PO blended fuels emit low percentage of CO, NOx, CO2, and HC – which essentially suggest a better life style by minimizing the health risks via reduction in greenhouse gas emission that may cause cardiovascular collapse, seizures, coma, and sometimes death. Thus, the present study will help in valorization and mitigation of generated waste plastics through energy conservation and boost the circular economy. The economic analysis based on the present investigation showed that ∼₹9.73 (0.12$) profit per litter can be achieved in the first year itself, while the profit in the 2nd and 5th year could be increased up to ₹54.43 (0.68$) and ₹67.73 (0.85$), respectively.