Upgraded medical waste recycling via magnetic catalyst combined with biomass pyrolysis: Thermal decomposition, product evolution, and sequential temperature-dependent responses

To achieve high-value utilization of medical waste and the net-zero target, introducing green and renewable biomass to upgrade medical waste via pyrolysis is considered a highly promising solution. This study achieves pyrolytic upgrading of medical waste syringes by incorporating walnut shells and rice husks, while the addition of the magnetic catalyst Fe₃O₄-NiO further promoted its efficient conversion. The addition of biomass enhanced the yield of volatile products and aromatic hydrocarbon. At the same time, the formation of pyrolytic char and CO₂ was suppressed. The char yield was reduced from the theoretical value of 23 % to the actual value of 15 %. Moreover, the peak temperature corresponding to the pyrolysis of discarded syringes decreased from 484 °C to 447 °C. The addition of the catalyst not only further effectively reduced the CO₂ concentration but also promoted the formation of light, high-value components. This study confirms the technical feasibility of using biomass to co-process plastic medical waste, offering a novel technical approach to tackling complex medical solid waste pollution issues. © 2026 Elsevier B.V.