Product Distribution and Quality Changes Induced by UV Pre-Treatment in Waste Tyre Pyrolysis

Abstract

The management of end-of-life tyres represents a growing environmental challenge. Pyrolysis provides a sustainable recycling pathway by converting waste tyres into oil, gas, and char, but the high sulphur content of these products limits their direct utilisation. This study investigates UV irradiation as a pre-treatment method to modify tyre rubber structure and influence subsequent pyrolysis behaviour. Shredded tyre samples were irradiated by UV light for 0, 360, and 1080 min prior to pyrolysis at 900 °C. Structural and morphological changes were characterised using Fourier transform infrared spectroscopy, microscopy, and thermogravimetry. Product yields were quantified, and the resulting oil, char, and gas fractions were analysed by elemental composition, heating value, and gas chromatography.UV pre-treatment induced oxidation, chain scission, and partial devulcanisation in the rubber matrix, leading to more homogeneous thermal degradation. At 900 °C, UV pre-treatment of 1080 min slightly increased gas yields, reduced oil yields, and left char production largely unchanged. Oils from irradiated samples exhibited higher oxygen and sulphur contents, resulting in lower heating values. Char composition remained relatively stable, with heating values of 8–9 MJ/kg. The gas fraction showed increased energy potential but also a higher hydrogen sulphide content. Overall, UV irradiation significantly altered tyre rubber structure and pyrolysis product quality. While the pre-treatment enhanced the energy potential of the gas fraction, it also intensified sulphur-related challenges, underscoring both the potential and limitations of UV-assisted tyre pyrolysis.

Affiliated Institutions

• University of Miskolc HU

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