Life cycle assessment as a tool for eco-design of modified materials for water treatment

• Life cycle assessment compared four clay modification routes. • Primary lab-scale inventories enabled cradle-to-gate evaluation. • Scenario-aggregated LCA showed polymerization with highest burdens. • Renewable electricity cut hybridization impacts by up to 97%. • Integrated LCA–CED–LCC–performance ranking: Act > MD > Hyb > Pol. Material modification is widely employed to improve the performance of pristine adsorbents for water treatment; however, the environmental and economic implications of different modification routes are rarely quantified and systematically compared. Most studies prioritize adsorption efficiency, with limited attention to the life-cycle burdens introduced during synthesis/modification. This study addresses this gap by performing a comparative life cycle assessment (LCA) and life cycle cost (LCC) analysis of four common modification methods activation, metal doping, hybridization, and polymerization applied to bentonite clay. Using primary laboratory-scale inventory data and a cradle-to-gate system boundary, environmental impacts were quantified using the CML-IA baseline and cumulative energy demand (CED) methods, while economic feasibility was evaluated through LCC. The most affected impact categories followed the order MAE >CED > AD (fossil fuels) > HT > GWP > FAE. The sensitivity analysis demonstrated that greener chemical choices and shifting from fossil‑based electricity to hydropower reduce burdens markedly, with hybridization showing up to 97% reduction due to its electricity‑intensive pyrolysis step. Overall environmental impacts of the modification techniques followed the order polymerization >hybridization>Metal doping>activation noting that this ranking varies with the choice of functional unit. Corresponding economic costs were $9.91, $198.34, $17.81, and $814 per kg for activation (Na₂CO₃), metal doping (iron oxide), hybridization (biochar), and polymerization, respectively. Integrating scenario‑aggregated LCA, CED with LCC and adsorption performance via equal‑weight LWS yielded the final overall sustainability ranking: Activation>Metal doping >Hybridization>Polymerization. Accordingly, the results indicate activation and metal doping offer more sustainable pathways than hybridization and polymerization. This study highlights the importance of developing adsorbents that balance minimal environmental impacts with optimal performance, providing practical guidance for the eco-design of high-performance materials for water treatment applications.