Magnesite-modified seaweed biochar-chitosan hydrogel beads for phosphate removal: adsorption mechanism, interpretable machine learning and life cycle assessment

). Mechanistic investigations further revealed that phosphate removal proceeded through multiple pathways, including surface precipitation, coordination interactions, and electrostatic attraction. Interpretable machine learning analysis based on tree-based models further showed that the initial phosphate concentration and contact time were the dominant variables governing adsorption performance, contributing ∼ 55% and ∼ 20%, respectively. A Python-based graphical user interface was additionally developed to facilitate experimental design and practical implementation. Life-cycle assessment indicated that the principal environmental impacts centered on marine and freshwater ecotoxicity, while carbon emissions were mainly associated with NaOH consumption and energy use. Overall, this work provides an effective waste-derived composite for phosphate removal and resource recovery, while offering mechanistic and sustainability insights for future optimization and greener fabrication.