A new study proposes a comprehensive framework for selecting sustainable adsorbents for water treatment by integrating adsorption performance with life cycle assessment and end-of-life analysis, addressing the environmental burden of conventional materials. Researchers from Kyung Hee University reported in Frontiers of Environmental Science & Engineering on August 23, 2025, that this multi-factor decision approach evaluates bio-based activated carbons produced from agricultural residues like pine bark, which offer promising alternatives to fossil-based adsorbents. The study emphasizes that most current evaluations rely on mass-based life cycle metrics, potentially overlooking real-world contaminant removal effectiveness, whereas performance-based assessments better reflect environmental benefits.
Using pine bark as a renewable precursor, the team synthesized activated carbons through five different chemical activation strategies, including single and dual treatments. Among these, dual activation with sodium hydroxide followed by hydrochloric acid produced an adsorbent with optimal surface structure and functional groups, achieving a maximum humic acid adsorption capacity of 15.84 mg per gram. This material outperformed both singly activated biochars and commercially available activated carbons, demonstrating superior contaminant removal efficiency. To assess sustainability, the researchers applied life cycle assessment using both mass-based and adsorption-capacity-based functional units, revealing that the dual-activated adsorbent had the lowest greenhouse gas emissions and cumulative energy demand per unit of pollutant removed due to reduced material requirements.
The analysis identified electricity use during drying and pyrolysis as major environmental hotspots in adsorbent production. A prospective scale-up model indicated that industrial-scale production could reduce carbon emissions per kilogram of adsorbent by nearly 90% compared to laboratory-scale synthesis, highlighting potential for significant environmental improvements. End-of-life analysis further showed that regenerating spent adsorbents offers substantial emission savings relative to landfilling or incineration, reinforcing the value of circular material strategies in water treatment systems. According to the authors, evaluating adsorbents solely on adsorption capacity or production emissions provides an incomplete picture of sustainability, and performance-based life cycle metrics are essential for guiding material design choices that contribute to carbon neutrality.
The proposed framework offers a practical tool for researchers, engineers, and policymakers seeking sustainable water treatment solutions by aligning adsorption efficiency with life cycle performance and end-of-life considerations. The findings suggest that optimally designed and regenerated bio-based activated carbons can significantly reduce the environmental footprint of water purification systems. The research is detailed in the study available at https://doi.org/10.1007/s11783-025-2068-6, providing a roadmap for developing net-zero-oriented adsorbents that balance high contaminant removal with low environmental impact.
