Sustainable adsorbent selection through green design: Linking water treatment performance, environmental impacts and scale-up scenarios

Abstract

Activated carbon (AC) is a highly versatile adsorbent utilized for water and wastewater treatment applications due to its strong adsorptive properties. However, the widely used conventional coal–derived ACs pose significant environmental concerns, necessitating the search for sustainable alternatives. The present study evaluates pyrolysis retention time optimized pine bark residue–derived adsorbent (PBA), for its adsorption capacity and environmental sustainability. The PBA featured a large specific surface area (506.88 m²/g), well–developed micro and mesopores, and surfaces functionalized with aromatic C=O and C=H, leading to the rapid removal of humic acid (q_max −9.81 mg/g). Cradle–to–gate life cycle assessment (LCA) was conducted with mass–based and the novel application–based functional units to fully explore the sustainability of the synthesized PBAs. In addition to conventional midpoint impact categories (TRACI), this study quantified the cumulative energy demand, endpoint impacts (human health, ecosystem degradation, and resource depletion), associated with PBA production. The study also critically quantifies the environmental impacts associated with the conventional adsorbents and benchmark PBA against its counterparts. Furthermore, the comprehensive scale–up framework provides valuable insights into identifying the full potential of AC production at pilot and industrial scales. In this aspect, the synchronous study involving both experimental analysis and LCA modeling establishes a structured and measurable framework for sustainable adsorbent development.