Abstract
Amid the projected depletion of petroleum products and the severe environmental challenges, this study addresses the urgent need for sustainable alternatives to fossil fuels by investigating co-pyrolysis as a means to valorize two different wastes. Groundnut shell and scrap tyres were individually pyrolyzed at 350–600 °C, while co-pyrolysis was conducted at an optimal temperature of 500 °C using tyre blend ratios of 20%, 40%, 50%, 60%, and 80%. Product yields, synergistic effects and properties of bio-oil, char, and gas were systematically evaluated. Individual groundnut shell pyrolysis favored high CO2 and oxygenated liquids with moderate heating value, whereas tyre pyrolysis produced hydrogen- and hydrocarbon-rich gases, carbon-dense char, and high-calorific oil. Co-pyrolysis demonstrated clear synergistic interactions, particularly at 40% tyre blending, yielding improved liquid fuel with higher calorific value, reduced oxygen content, and intermediate density and viscosity compared to the individual feedstocks. Co-pyrolysis char exhibited enhanced fixed carbon and reduced sulphur relative to tyre char alone, while gas fractions showed increased H2 and CH4 with lower CO2 than biomass pyrolysis. These improvements arise from complementary radical interactions and synergistic behavior of volatiles between the feedstocks. The results demonstrate that co-pyrolysis effectively optimizes product quality and energy potential, providing a sustainable pathway for simultaneous waste valorization, reduced greenhouse gas emissions, and renewable biofuel production in a circular economy framework.
Data availability
The datasets used and/or analysed during the current study available from the corresponding author on reasonable request.
References
Shafiee, S. & Topal, E. When will fossil fuel reserves be diminished? Energy Policy. 37 (1), 181–189. https://doi.org/10.1016/j.enpol.2008.08.016 (2009).
Babajo, S. A., Enaburekhan, J. S. & Rufa’i, I. A. Design, fabrication and performance study of co-pyrolysis system for production of liquid fuel from Jatropha cake with polystyrene waste. J. Appl. Sci. Environ. Manage. 25 (3), 407–414. https://doi.org/10.4314/jasem.v25i3.15 (2021).
Mao, G., Liu, X., Du, H., Zuo, J. & Wang, L. Way forward for alternative energy research: A bibliometric analysis during 1994–2013. Renew. Sustain. Energy Rev. 48, 276–286. https://doi.org/10.1016/j.rser.2015.03.094 (2015).
Koshariya, A. K. et al. Effect of acidic treatment for conventional processing and recent advances on lignocellulosic ricinus communis: A comparative evaluation on decomposition of biomass for environmental sustainability. Waste Biomass Valoriz. 15 (10), 6051–6064. https://doi.org/10.1007/s12649-024-02591-4 (2024).
Kumar, A. et al. Pyrolysis behaviour and synergistic effect in co-pyrolysis of wheat straw and polyethylene terephthalate: A study on product distribution and oil characterization. Heliyon 10 (17), e37255. https://doi.org/10.1016/j.heliyon.2024.e37255 (2024).
Muhmad, S. N., Cheema, S., Mohamad Ariff, A., Nik Him, N. F. & Muhmad, S. N. Systematic literature review and bibliometric analysis of green finance and renewable energy development. Sustain. Dev. 32 (6), 7342–7355. https://doi.org/10.1002/sd.3093 (2024).
Karthik, A. et al. Biomass and Operational Initiatives for Sustainable Bioenergy Generation. In E3S Web of Conferences Vol. 529, p. 02014. EDP Sciences. (2024). https://doi.org/10.1051/e3sconf/202452902014
Sliper, N. J. Energy utilization and conversion in modern biomass conversion technologies. J. Comput. Intell. Mater. Sci. 2, 001–011. https://doi.org/10.53759/832X/JCIMS202402001 (2024).
Hita, I. et al. Opportunities and barriers for producing high quality fuels from the pyrolysis of scrap tires. Renew. Sustain. Energy Rev. 56, 745–759. https://doi.org/10.1016/j.rser.2015.11.081 (2016).
Bridgwater, T. Biomass for energy. J. Sci. Food. Agric. 86 (12), 1755–1768. https://doi.org/10.1002/jsfa.2605 (2006).
Hussein, A. M., Kar, Y. & Kök, O. E. Co-Pyrolysis of walnut shell and waste tire with a focus on bio-oil yield quantity and quality. J. Energy Inst. 112, 101494. https://doi.org/10.1016/j.joei.2023.101494 (2024).
Zheng, D. M., Lu, Q. F., Liu, M. & Chen, Y. X. Study on the catalytic cracking of waste plastics and waste lubricating oil for producing fuel oil. Mod. Chem. Ind. 31 (8), 47–49 (2011).
Tandon, V., Velazco, D. A., Nazarian, S. & Picornell, M. Performance monitoring of embankments containing tire chips: case study. J. Perform. Constr. Facil. 21 (3), 207–214. https://doi.org/10.1061/(ASCE)0887-3828(2007)21:3(207 (2007).
Singh, M., Salaudeen, S. A., Gilroyed, B. H., Al-Salem, S. M. & Dutta, A. A review on co-pyrolysis of biomass with plastics and tires: recent progress, catalyst development, and scaling up potential. Biomass Convers. Biorefinery. 13 (10), 8747–8771. https://doi.org/10.1007/s13399-021-01818-x (2023).
Li, C. et al. Co-pyrolysis of waste paper and tyre: exploration of interaction of volatiles of varied origin and the influence on product evolution. J. Anal. Appl. Pyrol. 178, 106395. https://doi.org/10.1016/j.jaap.2024.106395 (2024).
Rajput, G., Liu, B., Pan, M., Kumar, A., Kumari, L., Farooq, M. Z., … Ma, W. (2024).Valorizing polymeric wastes and biomass through optimized co-pyrolysis for upgraded pyrolysis oil: A study on TG-FTIR and fixed bed reactor. Journal of Analytical and Applied Pyrolysis, 182, 106686. https://doi.org/10.1016/j.jaap.2024.106686.
Abnisa, F. & Daud, W. M. A. W. Optimization of fuel recovery through the Stepwise co-pyrolysis of palm shell and scrap tire. Energy. Conv. Manag. 99, 334–345. https://doi.org/10.1016/j.enconman.2015.04.030 (2015).
Uçar, S. & Karagöz, S. Co-pyrolysis of pine nut shells with scrap tires. Fuel 137, 85–93. https://doi.org/10.1016/j.fuel.2014.07.082 (2014).
Farooq, M. Z., Zeeshan, M., Iqbal, S., Ahmed, N. & Shah, S. A. Y. Influence of waste tire addition on wheat straw pyrolysis yield and oil quality. Energy 144, 200–206. https://doi.org/10.1016/j.energy.2017.12.026 (2018).
Ahmed, N., Zeeshan, M., Iqbal, N., Farooq, M. Z. & Shah, S. A. Investigation on bio-oil yield and quality with scrap tire addition in sugarcane Bagasse pyrolysis. J. Clean. Prod. 196, 927–934. https://doi.org/10.1016/j.energy.2017.12.026 (2018).
Fei, J., Zhang, J., Wang, F. & Wang, J. Synergistic effects on co-pyrolysis of lignite and high-sulfur swelling coal. J. Anal. Appl. Pyrol. 95, 61–67. https://doi.org/10.1016/j.jaap.2012.01.006 (2012).
Huang, S. & Sheng, J. J. An innovative method to build a comprehensive kinetic model for air injection using TGA/DSC experiments. Fuel 210, 98–106. https://doi.org/10.1016/j.fuel.2017.08.048 (2017).
Hai, A. et al. Valorization of groundnut shell via pyrolysis: product distribution, thermodynamic analysis, kinetic estimation, and artificial neural network modeling. Chemosphere 283, 131162. https://doi.org/10.1016/j.chemosphere.2021.131162 (2021).
Mohammed, I. Y. et al. Valorization of Bambara groundnut shell via intermediate pyrolysis: products distribution and characterization. J. Clean. Prod. 139, 717–728. https://doi.org/10.1016/j.jclepro.2016.08.090 (2016).
Wang, L., Chai, M., Liu, R. & Cai, J. Synergetic effects during co-pyrolysis of biomass and waste tire: A study on product distribution and reaction kinetics. Bioresour. Technol. 268, 363–370. https://doi.org/10.1016/j.biortech.2018.07.153 (2018).
Dwivedi, C., Manjare, S. & Rajan, S. K. Recycling of waste tire by pyrolysis to recover carbon black: alternative & environment-friendly reinforcing filler for natural rubber compounds. Compos. Part. B: Eng. 200, 108346. https://doi.org/10.1016/j.compositesb.2020.108346 (2020).
Ramya, G., Sailesh, A., Madhu, P. & Sowmya Dhanalakshmi, C. A comprehensive thermal and analytical characterization study on biofuel produced from pyrolysis of Gingergrass at different operating conditions. Biofuels 1–21. https://doi.org/10.1080/17597269.2025.2553994 (2025).
Chandrasekran, G., Ahalya, N., Pamila, R., Madhu, P., Vidhya, L., Vinodha, S., …Lalvani, J. I. J. (2024). Thermal degradation of emerging pollutants in municipal solid wastes and agro wastes: effectiveness of catalysts and pretreatment for the conversion of value added products. Discover Applied Sciences, 6(4), 172. https://doi.org/10.1007/s42452-024-05844-y.
Ueno, T., Nakashima, E. & Takeda, K. Quantitative analysis of random scission and chain-end scission in the thermal degradation of polyethylene. Polym. Degrad. Stab. 95 (9), 1862–1869. https://doi.org/10.1016/j.polymdegradstab.2010.04.020 (2010).
Varkey, J. T., Augustine, S. & Thomas, S. Thermal degradation of natural rubber/styrene butadiene rubber latex blends by thermogravimetric method. Polym.-Plast. Technol. Eng. 39 (3), 415–435. https://doi.org/10.1081/PPT-100100038 (2000).
Senneca, O., Salatino, P. & Chirone, R. A fast heating-rate thermogravimetric study of the pyrolysis of scrap tyres. Fuel 78 (13), 1575–1581. https://doi.org/10.1016/S0016-2361(99)00087-3 (1999).
Han, W., Han, D. & Chen, H. Pyrolysis of waste tires: a review. Polymers 15 (7), 1604. https://doi.org/10.3390/polym15071604 (2023).
Demirbas, A. Effect of temperature on pyrolysis products from biomass. Energy Sources Part. A. 29 (4), 329–336. https://doi.org/10.1080/009083190965794 (2007).
Zhang, Y. et al. A review of biomass pyrolysis gas: forming mechanisms, influencing parameters, and product application upgrades. Fuel 347, 128461. https://doi.org/10.1016/j.fuel.2023.128461 (2023).
Chang, Z. et al. Environmental implications of residual pyrogenic carbonaceous materials from incomplete biomass combustion: a review. Carbon Res. 3 (1), 15. https://doi.org/10.1007/s44246-024-00103-6 (2024).
Ephraim, A. et al. Co-pyrolysis of wood and plastics: influence of plastic type and content on product yield, gas composition and quality. Fuel 231, 110–117. https://doi.org/10.1016/j.fuel.2018.04.140 (2018).
Singh, R. K. et al. Pyrolysis of three different categories of automotive tyre wastes: product yield analysis and characterization. J. Anal. Appl. Pyrol. 135, 379–389. https://doi.org/10.1016/j.jaap.2018.08.011 (2018).
Erliyanti, N. K., Sangian, H. F., Susianto, S. & Altway, A. The preparation of fixed carbon derived from waste tyre using pyrolysis. Scientific Study & Research. Chemistry & Chemical Engineering, Biotechnology, Food Industry, 16(4), 343. (2015).
Tan, V. et al. Waste tyre char-catalysed in-situ deoxygenation of volatile vapours and production of hydrogen-rich syngas during the pyrolysis of lignite. Fuel Processing Technology, 218, 106872. (2021). https://doi.org/10.1016/j.fuproc.2021.106872
Razzak, S. A. Municipal solid and plastic waste Co-pyrolysis towards sustainable renewable fuel and carbon materials: A comprehensive review. Chemistry–An Asian J. 19 (17), e202400307. https://doi.org/10.1002/asia.202400307 (2024).
Kaushik, V. S., Dhanalakshmi, C. S., Madhu, P. & Tamilselvam, P. Co-pyrolysis of Neem wood bark and low-density polyethylene: influence of plastic on pyrolysis product distribution and bio-oil characterization. Environ. Sci. Pollut. Res. 29 (58), 88213–88223. https://doi.org/10.1007/s11356-022-21746-1 (2022).
Dębek, C. Modification of pyrolytic oil from waste tyres as a promising method for light fuel production. Materials 12 (6), 880. https://doi.org/10.3390/ma12060880 (2019).
Alvarez, J. et al. Improving bio-oil properties through the fast co-pyrolysis of lignocellulosic biomass and waste tyres. Waste Manage. 85, 385–395. https://doi.org/10.1016/j.wasman.2019.01.003 (2019).
Kumar, I., Tirlangi, S., Kathiresan, K., Sharma, V., Madhu, P., Sathish, T., … Murugan,P. (2024). Co-pyrolysis of furniture wood with mixed plastics and waste tyres: assessment of synergistic effect on biofuel yield and product characterization under different blend ratio. Scientific reports, 14(1), 24584. https://doi.org/10.1038/s41598-024-72809-x.
Wongkhorsub, C. & Chindaprasert, N. A comparison of the use of pyrolysis oils in diesel engine. Energy Power Eng. 5 (4), 350–355. https://doi.org/10.4236/epe.2013.54B068 (2013).
Fardhyanti, D. S. et al. Phenolic compound separation from bio-oil produced from pyrolysis of coffee shell at 700° c using liquid-liquid extraction. In Journal of Physics: Conference Series (Vol. 1444, No. 1, p. 012002). IOP Publishing. (2020). https://doi.org/10.1088/1742-6596/1444/1/012002
Kamesh, M. R., Kumar, P. S., Vijayalakshmi, A., Dubey, S., Madhu, P., Dhanalakshmi,C. S., … Subramani, N. (2025). Interaction between sewage sludge and biomass components for enhanced biofuel production via pyrolysis based on studies of the mild acid pre-treatment process. Journal of the Energy Institute, 121, 102167. https://doi.org/10.1016/j.joei.2025.102167.
Saravanakumar, K., Robinson, Y., Madhu, P. & Manoj, M. Selection of oil and best Bio-diesel blend based on performance and emission characteristics of IC engine: an integrated CRITIC-TOPSIS approac. J. Sci. Ind. Res. 81 (12), 1342–1352. https://doi.org/10.56042/jsir.v81i12.47120 (2022).
Zhong, D. et al. Characteristics and evolution of heavy components in bio-oil from the pyrolysis of cellulose, hemicellulose and lignin. Renew. Sustain. Energy Rev. 157, 111989. https://doi.org/10.1016/j.rser.2021.111989 (2022).
Elakiya, N. & Arulmozhiselvan, K. Characterization of substrates of growing media by fourier transform infrared (FT-IR) spectroscopy for containerized crop production. J. Appl. Nat. Sci. 13 (SI), 35–42. https://doi.org/10.31018/jans.v13iSI.2774 (2021).
Mahamulkar, S. et al. Formation and oxidation/gasification of carbonaceous deposits: a review. Ind. Eng. Chem. Res. 55 (37), 9760–9818. https://doi.org/10.1021/acs.iecr.6b02220 (2016).
Sibeko, M. A., Adeniji, A. O., Okoh, O. O. & Hlangothi, S. P. Trends in the management of waste tyres and recent experimental approaches in the analysis of polycyclic aromatic hydrocarbons (PAHs) from rubber crumbs. Environ. Sci. Pollut. Res. 27 (35), 43553–43568. https://doi.org/10.1007/s11356-020-09703-2 (2020).
Lin, Q. et al. Transformation and mitigation of Tar and related secondary pollutants during sewage sludge pyrolysis. Water 16 (14), 2066. https://doi.org/10.3390/w16142066 (2024).
Sowmya Dhanalakshmi, C. & Madhu, P. Biofuel production of Neem wood bark (Azadirachta indica) through flash pyrolysis in a fluidized bed reactor and its chromatographic characterization. Energy Sour. Part A Recover. Utilization Environ. Eff. 43 (4), 428–443. https://doi.org/10.1080/15567036.2019.1624893 (2021).
Wang, K. et al. Kinetic,thermodynamic and synergistic effects of pyrolysis of natural rubber, styrene-butadiene rubber and butadiene rubber. Fuel 372, 132088. https://doi.org/10.1016/j.fuel.2024.132088 (2024).
Mehanathan, S., Madhu, P., Dhanalakshmi, C. S. & Vijayakumar, R. Synergistic recovery of renewable hydrocarbon resources via co-pyrolysis of non-edible linseed and waste polypropylene: a study on influence of plastic on oil production and their utilization as a fuel for IC engine. J. Energy Inst. 118, 101905. https://doi.org/10.1016/j.joei.2024.101905 (2025).
Muttil, N., Jagadeesan, S., Chanda, A., Duke, M. & Singh, S. K. Production, types, and applications of activated carbon derived from waste tyres: an overview. Appl. Sci. 13 (1), 257. https://doi.org/10.3390/app13010257 (2022).
Mavukwana, A. E. & Sempuga, C. Recent developments in waste tyre pyrolysis and gasification processes. Chem. Eng. Commun. 209 (4), 485–511. https://doi.org/10.1080/00986445.2020.1864624 (2022).
Akhtar, M. S., Naseem, M. T., Ali, S. & Zaman, W. Metal-Based catalysts in biomass transformation: from plant feedstocks to renewable fuels and chemicals. Catalysts 15 (1), 40. https://doi.org/10.3390/catal15010040 (2025).
Jiang, H. et al. Desulfurization and upgrade of pyrolytic oil and gas during waste tires pyrolysis: the role of metal oxides. Waste Manage. 182, 44–54. https://doi.org/10.1016/j.wasman.2024.04.020 (2024).
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M.A conceptualized the study, P.S.K did Data Curation, D.O and M.P did Formal analysis, J.M and S.K Investigated the study, L.P.T.R and S.D supervised the project and K.M.H prepared the draft.
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Anusuya, M., Kumar, P.S., Ommurugadhasan, D. et al. Investigating synergistic effects in Co-prolysis of groundnut shell and waste tyres on product distribution under different blend ratios. Sci Rep (2026). https://doi.org/10.1038/s41598-026-38993-8
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DOI: https://doi.org/10.1038/s41598-026-38993-8