Life cycle assessment of structurally recoverable activated carbon composites from sugarcane bagasse and mixed plastic waste

The co-valorization of agricultural residues and mixed plastic waste (MPW) into structured adsorbents offers a promising pathway for developing circular and recoverable water-treatment materials. In this study, a structurally recoverable activated carbon (AC) composite based on sugarcane bagasse (SB) and MPW was developed, and its environmental sustainability was evaluated using life cycle assessment (LCA). Two alkali-based activation routes (NaOH and KOH) were assessed using dual functional units: (i) per kg of composite produced and (ii) per kg of dye adsorbed. On a mass basis, the NaOH route exhibited lower environmental burdens, with climate change (CC) impacts of 5.61 kg CO 2 -eq compared to 5.82 kg CO 2 -eq for the KOH route, and net energy demand (EN) of 142 MJ versus 148 MJ, respectively. Contribution analysis identified pyrolysis and polymer dissolution as the dominant environmental hotspots across most midpoint categories. Electricity scenario analysis showed that hard coal resulted in the highest CC impact, whereas photovoltaic electricity exhibited the highest EN because of upstream manufacturing burdens. Benchmarking against commercial AC indicated that the SB–MPW composites achieved comparable CC and EN while providing a waste-derived, structurally recoverable alternative. Sensitivity analysis identified pyrolysis electricity demand as the most influential parameter, whereas neutralization had only a minor influence. On a performance basis (per kg of dye adsorbed), the higher adsorption capacity of the KOH-derived composite reduced CC and EN (12.9 kg CO 2 -eq and 328 MJ) relative to the NaOH-derived composite (15.4 kg CO 2 -eq and 391 MJ), highlighting the importance of performance-normalized LCA for adsorption systems. Environmental impacts could be further reduced by lowering energy consumption during pyrolysis and improving solvent recovery. This study demonstrates that SB and MPW can be integrated into structurally stable, adsorption-capable composites with competitive environmental performance while improving material recovery and circularity, thereby bridging the gap between adsorption efficiency and practical recoverability in aqueous systems.