Synergistic co-pyrolysis of Gracilaria waste and waste tires: Enhancing bio-oil quality through thermal and chemical bond optimization

The increasing demand for renewable energy and sustainable waste management has prompted research into innovative conversion technologies. This study explored the co-pyrolysis of Gracilaria waste (GW) and waste tires (WT) as a potential approach to improving bio-oil quality by enhancing its hydrocarbon content and reducing oxygenated compounds. The novelty of this study lay in providing new mechanistic insights into the co-pyrolysis process by systematically analyzing the thermal degradation behavior and chemical bond evolution of GW-WT mixtures using a combination of TGA, FTIR, and GC-MS techniques. This detailed chemical transformation analysis differentiated the study from prior research that primarily focused on product yields. The study analyzed the thermal degradation behavior and chemical bond transformation of GW and WT mixtures during pyrolysis, hypothesizing that the addition of WT to GW would enhance the hydrocarbon profile and thermal stability of the resulting bio-oil. Thermogravimetric analysis (TGA) was employed to evaluate the decomposition behavior of five different GW-WT blend ratios under an inert atmosphere, while Fourier Transform Infrared Spectrosco py (FTIR) was used to assess chemical functional group evolution in both raw materials and pyrolytic products. The results revealed that GW pyrolysis exhibited a single weight loss peak (100–350°C) with a total weight loss of 40%, while WT pyrolysis followed a two-stage decomposition process (200–500°C) with a total weight loss of 65%. The GW-WT mixture resulted in a total weight loss of approximately 60%, indicating a synergistic effect between the two feedstocks. FTIR analysis confirmed a reduction in hydroxyl (-OH) groups and an increase in hydrocarbon-related bonds (C=C, C-C, and C-H), demonstrating improved bio-oil composition. These findings suggested that incorporating waste tires into Gracilaria pyrolysis enhanced bio-oil quality and hydrocarbon content, offering a promising approach for biomass valorization and sustainable energy production. Future research should explore process optimization through catalyst integration and scale-up potential for industrial applications.