Pyrolysis oil from polypropylene packaging waste: a sustainable waste‑to‑resource approach for non‑coking coal flotation

Abstract

Due to declining fossil fuel reserves and increasing petroleum costs, finding cost-effective alternatives for beneficiating highash coal is essential. Coal’s inherent hydrophobicity makes froth flotation a favorable technique, with diesel typically used as the collector. This study explores the use of pyrolysis oil (PP oil), derived from non-biodegradable polypropylene packaging waste, as a sustainable alternative to diesel in non-coking coal flotation. The research employed a central composite design (CCD) to assess the flotation performance of PP oil as collector and optimize the flotation process by identifying the influence of significant factors. Under optimized flotation conditions employing 6 ml of pyrolysis oil and 1 ml of methyl isobutyl carbinol (MIBC) as frother, the process achieved a clean coal yield of 71.25%. The ash content was effectively reduced from 34.6% in the feed to 12.38% in the product, demonstrating the efficacy of the reagent combination in enhancing separation performance. Analysis of variance (ANOVA) and regression analyses evaluated the impact of process parameters on yield and ash content, while Fourier-transform infrared spectroscopy (FTIR) analysis assessed the presence of functional groups in the PP oil that facilitate its collector functionality. Replacing traditional diesel with PP oil in coal flotation offers a significant step toward a more sustainable and potentially more economical coal beneficiation process.