Evaluating environmental and economic sustainability of engineered chitosan particles for water treatment

• TEA and LCA evaluate cost and environmental impacts of three engineered chitosan particles. • APCP shows lowest cost (32.89 USD/g) while MPCP achieves highest methylene blue removal (>90 %). • Normalization method drastically alters sustainability rankings of chitosan particles. • Mass-normalized vs. removal-normalized metrics reveal different optimal particle designs. • Sensitivity analysis identifies precursor selection and energy use as key sustainability drivers. The global water demands have prompted the development of sustainable treatment solutions, with adsorptive chitosan composites emerging as promising alternatives to petroleum-based materials. As a cleaner material, chitosan offers significant advantages over conventional adsorbents, including biodegradability, biocompatibility, and the potential to create a circular economy in water treatment applications. This study presents a comprehensive sustainability assessment of three novel porous chitosan particles synthesized using low-toxicity solvents, focusing solely on the production of pure chitosan scaffolds without additional adsorptive materials for targeted removal. Integrating techno-economic analysis and life cycle assessment, we evaluate the economic viability and environmental impact of methylpentane, azocarboxamide, and tween porous chitosan particles. Our analysis, normalized to both production mass and methylene blue removal efficiency, reveals complex tradeoffs among costs, environmental impacts, and performance. Azocarboxamide particles was the most cost-effective in production at 32.89 [26.13-41.00] USD/g, while having greater environmental impacts and less removal (< 20 %). In contrast, methylpentane particles demonstrated superior environmental sustainability, achieving a removal efficiency of > 90 % with moderate production cost of 104.07 [80.76-135.07] USD/g. This divergence in results highlights the critical importance of considering both production costs and functional performance when evaluating the sustainability of these materials. Sensitivity analysis identified key sustainability drivers, including precursor costs, synthesis yield, material quantities, and energy consumption. These findings underscore the importance of optimizing synthesis conditions and considering full life cycle impacts in developing chitosan-based adsorbents. This study provides a robust framework for evaluating the sustainability of biopolymer-based materials and supports informed decision-making in advancing water treatment technologies and promoting a circular economy.