Biomimetic Construction of Enteromorpha prolifera-Based Composite Membranes for Synergistic Purification of Fluoride Ions, Bacteria, and Dye with High Sustainability

As an essential trace element in the human body, fluoride is beneficial in appropriate amounts, but excessive intake can cause serious harm. Therefore, addressing the global water pollution caused by fluoride is an urgent issue. In this study, a functional composite membrane is successfully prepared using <i>Enteromorpha prolifera</i> (EP) as the raw material, cinnamaldehyde (CIN) as a functional modifier, and EP-bioinduced ZrO₂ nanoparticles (NPs) as the loading material via biomimetic mineralization technology. The experimental results demonstrate that the composite membrane removes fluoride ions (F^-) with an efficiency of over 99.9% within the concentration range of 100-400 mg/L. This excellent F^- removal performance is attributed to the ability of the hydroxyl groups on the surface of ZrO₂ to exchange and bind with F^-. The formed CIN/EP-ZrO₂ composite membrane also reveals significant antibacterial activity against <i>E. coli</i>. In addition, the adsorption rate for methylene blue at the concentration of 5-300 mg/L reaches 99.99%, which is due to the synergistic interaction of functional groups such as hydroxyl (-OH), carboxyl (-COOH), and amino groups (-NH₂) in EP. The overall sustainability footprint (OSF) assessment exhibits that the CIN/EP-ZrO₂ composite membrane has comprehensive advantages, including a simple preparation process, low cost, high performance, and environmental friendliness. This study provides an innovative solution for the sustainable treatment of F^-, bacteria, and dye pollution in water, showcasing significant potential for applications in environmental science.